Compact self-contained electrical-to-optical converter/transmitter

DOEpatents

Seligmann, D.A.; Moss, W.C.; Valk, T.C.; Conder, A.D.

1995-11-21

A first optical receiver and a second optical receiver are provided for receiving a calibrate command and a power switching signal, respectively, from a remote processor. A third receiver is provided for receiving an analog electrical signal from a transducer. A calibrator generates a reference signal in response to the calibrate command. A combiner mixes the electrical signal with the reference signal to form a calibrated signal. A converter converts the calibrated signal to an optical signal. A transmitter transmits the optical signal to the remote processor. A primary battery supplies power to the calibrator, the combiner, the converter, and the transmitter. An optically-activated switch supplies power to the calibrator, the combiner, the converter, and the transmitter in response to the power switching signal. An auxiliary battery supplies power continuously to the switch. 13 figs.

Electrical modulation of the complex refractive index in mid-infrared quantum cascade lasers.

PubMed

Teissier, J; Laurent, S; Manquest, C; Sirtori, C; Bousseksou, A; Coudevylle, J R; Colombelli, R; Beaudoin, G; Sagnes, I

2012-01-16

We have demonstrated an integrated three terminal device for the modulation of the complex refractive index of a distributed feedback quantum cascade laser (QCL). The device comprises an active region to produce optical gain vertically stacked with a control region made of asymmetric coupled quantum wells (ACQW). The optical mode, centered on the gain region, has a small overlap also with the control region. Owing to the three terminals an electrical bias can be applied independently on both regions: on the laser for producing optical gain and on the ACQW for tuning the energy of the intersubband transition. This allows the control of the optical losses at the laser frequency as the absorption peak associated to the intersubband transition can be electrically brought in and out the laser transition. By using this function a laser modulation depth of about 400 mW can be achieved by injecting less than 1 mW in the control region. This is four orders of magnitude less than the electrical power needed using direct current modulation and set the basis for the realisation of electrical to optical transducers.

Surface plasmon resonance-based highly sensitive optical touch sensor with a hybrid noise rejection scheme.

PubMed

Sumriddetchkajorn, Sarun; Chaitavon, Kosom

2006-01-01

A surface plasmon resonance (SPR)-based optical touch sensor structure is proposed that provides high switch sensitivity and requires a weak activating force. Our proposed SPR-based optical touch sensor is arranged in a compact Kretschmann-Raether configuration in which the prism acting as our sensor head is coated with a metal nanofilm. Our optical-based noise rejection scheme relies on wavelength filtering, spatial filtering, and high reflectivity of the metal nanofilm, whereas our electrical-based noise reduction is obtained by means of an electrical signal filtering process. In our experimental proof of concept, a visible laser diode at a 655 nm centered wavelength and a prism made from BK7 with a 50 nm thick gold layer on the touching surface are used, showing a 7.85 dB optical contrast ratio for the first touch. An estimated weak mechanical force of <0.1 N is also observed that sufficiently activates the desired electrical load. It is tested for 51 operations without sensor malfunction under typical and very high illumination of 342 and 3000 lx, respectively. In this case, a measured average optical contrast of 0.80 dB is obtained with a +/-0.47 dB fluctuation, implying that the refractive index change in a small 3.2% of the overall active area is enough for our SPR-based optical touch sensor to function properly. Increasing optical contrast in our SPR-based optical touch sensor can be accomplished by using a higher polarization-extinction ratio and a narrower-bandwidth optical beam. A controlled environment and gold-coated surface using the thin-film sputtering technique can help improve the reliability and the durability of our SPR-based optical touch sensor. Other key features include ease of implementation, prevention of a light beam becoming incident on the user, and the ability to accept both strong and weak activating forces.

Optical and electrical stability of viral-templated copper sulfide (Cu{sub 1.8}S) films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shahriar Zaman, Mohammed; Bernard Grajeda, Gabriel; Haberer, Elaine D., E-mail: haberer@ucr.edu

The optical and electrical stabilities of viral-templated non-stoichiometric copper sulfide, digenite (Cu{sub 1.8}S) films were investigated. The films were composed of large agglomerates of randomly aligned Cu{sub 1.8}S-coated M13 filamentous phage. Free carrier optical absorption associated with localized surface plasmon resonance (LSPR) was observed in the near infrared spectral region, and the films were electrically active, displaying a linear current-voltage relationship. Under ambient conditions, the magnitude of the LSPR absorption increased, following a power law relationship with time, and the electrical resistance of viral-templated films decreased significantly. In contrast, the resistance of films stored under low oxygen, low humidity conditionsmore » experienced a smaller reduction in electrical resistance. Changes in optical and electrical film properties under ambient conditions were associated with an increase in free carrier concentration within the copper chalcogenide material due to oxygen exposure. X-ray photoelectron spectroscopy was used to relate this increase in free carrier concentration to compositional changes on the viral-templated material surface.« less

Failure analysis of InGaN/GaN high power light-emitting diodes fabricated with ITO transparent p-type electrode during accelerated electro-thermal stress.

PubMed

Moon, Seong Min; Kim, Y D; Oh, S K; Park, M J; Kwak, Joon Seop

2012-05-01

We have investigated the high-temperature degradation of optical power as well as electrical properties of InGaN/GaN light-emitting diodes (LEDs) fabricated with ITO transparent p-electrode during accelerated electro-thermal stress. As the thermal stress increased from 150 degrees C to 250 degrees C at a electrical stress of 200 mA, the optical power of the LEDs was significantly reduced. Degradation of the optical power was thermally activated, with the activation of 0.9 eV. In addition, the activation energy of the degradation of optical power was fairly similar to that of the degradation of series resistance of the LEDs, 1.0 eV, which implies that the increase in the series resistance may result in the severe degradation of optical power. We also showed that the increase in the series resistance of the LEDs during the accelerated electro-thermal stress can be attributed to reduction of the active acceptor concentration in the p-type semiconductor layers and local joule heating due to the current crowding.

Detection of cortical optical changes during seizure activity using optical coherence tomography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ornelas, Danielle; Hasan, Md.; Gonzalez, Oscar; Krishnan, Giri; Szu, Jenny I.; Myers, Timothy; Hirota, Koji; Bazhenov, Maxim; Binder, Devin K.; Park, Boris H.

2017-02-01

Electrophysiology has remained the gold standard of neural activity detection but its resolution and high susceptibility to noise and motion artifact limit its efficiency. Imaging techniques, including fMRI, intrinsic optical imaging, and diffuse optical imaging, have been used to detect neural activity, but rely on indirect measurements such as changes in blood flow. Fluorescence-based techniques, including genetically encoded indicators, are powerful techniques, but require introduction of an exogenous fluorophore. A more direct optical imaging technique is optical coherence tomography (OCT), a label-free, high resolution, and minimally invasive imaging technique that can produce depth-resolved cross-sectional and 3D images. In this study, we sought to examine non-vascular depth-dependent optical changes directly related to neural activity. We used an OCT system centered at 1310 nm to search for changes in an ex vivo brain slice preparation and an in vivo model during 4-AP induced seizure onset and propagation with respect to electrical recording. By utilizing Doppler OCT and the depth-dependency of the attenuation coefficient, we demonstrate the ability to locate and remove the optical effects of vasculature within the upper regions of the cortex from in vivo attenuation calculations. The results of this study show a non-vascular decrease in intensity and attenuation in ex vivo and in vivo seizure models, respectively. Regions exhibiting decreased optical changes show significant temporal correlation to regions of increased electrical activity during seizure. This study allows for a thorough and biologically relevant analysis of the optical signature of seizure activity both ex vivo and in vivo using OCT.

Optical activity of chirally distorted nanocrystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tepliakov, Nikita V.; Baimuratov, Anvar S.; Baranov, Alexander V.

2016-05-21

We develop a general theory of optical activity of semiconductor nanocrystals whose chirality is induced by a small perturbation of their otherwise achiral electronic subsystems. The optical activity is described using the quantum-mechanical expressions for the rotatory strengths and dissymmetry factors introduced by Rosenfeld. We show that the rotatory strengths of optically active transitions are decomposed on electric dipole and magnetic dipole contributions, which correspond to the electric dipole and magnetic dipole transitions between the unperturbed quantum states. Remarkably, while the two kinds of rotatory strengths are of the same order of magnitude, the corresponding dissymmetry factors can differ bymore » a factor of 10{sup 5}. By maximizing the dissymmetry of magnetic dipole absorption one can significantly enhance the enantioselectivity in the interaction of semiconductor nanocrystals with circularly polarized light. This feature may advance chiral and analytical methods, which will benefit biophysics, chemistry, and pharmaceutical science. The developed theory is illustrated by an example of intraband transitions inside a semiconductor nanocuboid, whose rotatory strengths and dissymmetry factors are calculated analytically.« less

Optical activity of chirally distorted nanocrystals

NASA Astrophysics Data System (ADS)

Tepliakov, Nikita V.; Baimuratov, Anvar S.; Baranov, Alexander V.; Fedorov, Anatoly V.; Rukhlenko, Ivan D.

2016-05-01

We develop a general theory of optical activity of semiconductor nanocrystals whose chirality is induced by a small perturbation of their otherwise achiral electronic subsystems. The optical activity is described using the quantum-mechanical expressions for the rotatory strengths and dissymmetry factors introduced by Rosenfeld. We show that the rotatory strengths of optically active transitions are decomposed on electric dipole and magnetic dipole contributions, which correspond to the electric dipole and magnetic dipole transitions between the unperturbed quantum states. Remarkably, while the two kinds of rotatory strengths are of the same order of magnitude, the corresponding dissymmetry factors can differ by a factor of 105. By maximizing the dissymmetry of magnetic dipole absorption one can significantly enhance the enantioselectivity in the interaction of semiconductor nanocrystals with circularly polarized light. This feature may advance chiral and analytical methods, which will benefit biophysics, chemistry, and pharmaceutical science. The developed theory is illustrated by an example of intraband transitions inside a semiconductor nanocuboid, whose rotatory strengths and dissymmetry factors are calculated analytically.

Stretchable Transparent Electrode Arrays for Simultaneous Electrical and Optical Interrogation of Neural Circuits in Vivo.

PubMed

Zhang, Jing; Liu, Xiaojun; Xu, Wenjing; Luo, Wenhan; Li, Ming; Chu, Fangbing; Xu, Lu; Cao, Anyuan; Guan, Jisong; Tang, Shiming; Duan, Xiaojie

2018-05-09

Recent developments of transparent electrode arrays provide a unique capability for simultaneous optical and electrical interrogation of neural circuits in the brain. However, none of these electrode arrays possess the stretchability highly desired for interfacing with mechanically active neural systems, such as the brain under injury, the spinal cord, and the peripheral nervous system (PNS). Here, we report a stretchable transparent electrode array from carbon nanotube (CNT) web-like thin films that retains excellent electrochemical performance and broad-band optical transparency under stretching and is highly durable under cyclic stretching deformation. We show that the CNT electrodes record well-defined neuronal response signals with negligible light-induced artifacts from cortical surfaces under optogenetic stimulation. Simultaneous two-photon calcium imaging through the transparent CNT electrodes from cortical surfaces of GCaMP-expressing mice with epilepsy shows individual activated neurons in brain regions from which the concurrent electrical recording is taken, thus providing complementary cellular information in addition to the high-temporal-resolution electrical recording. Notably, the studies on rats show that the CNT electrodes remain operational during and after brain contusion that involves the rapid deformation of both the electrode array and brain tissue. This enables real-time, continuous electrophysiological monitoring of cortical activity under traumatic brain injury. These results highlight the potential application of the stretchable transparent CNT electrode arrays in combining electrical and optical modalities to study neural circuits, especially under mechanically active conditions, which could potentially provide important new insights into the local circuit dynamics of the spinal cord and PNS as well as the mechanism underlying traumatic injuries of the nervous system.

Photovoltaic Performance of Inverted Polymer Solar Cells Using Hybrid Carbon Quantum Dots and Absorption Polymer Materials

NASA Astrophysics Data System (ADS)

Lim, Hwain; Lee, Kyu Seung; Liu, Yang; Kim, Hak Yong; Son, Dong Ick

2018-05-01

We report the synthesis and characterization of the carbon quantum dots (C-dots) easily obtained from citric acid and ethanediamine, and also investigated structural, optical and electrical properties. The C-dots have extraordinary optical and electrical features such as absorption of ultraviolet range and effective interface for charge separation and transport in active layer, which make them attractive materials for applications in photovoltaic devices (PV). The C-dots play important roles in charge extraction in the PV structures, they can be synthesized by a simple method and used to insert in active layer of polymer solar cells. In this study, we demonstrate that improve charge transport properties of inverted polymer solar cells (iPSCs) with C-dots and structural, optical and electrical properties of C-dots. As a result, iPSCs with C-dots showed enhancement of more than 30% compared with that of the contrast device in power conversion efficiency.

Optical and electrical properties of mechanochemically synthesized nanocrystalline delafossite CuAlO2.

PubMed

Prakash, T; Prasad, K Padma; Ramasamy, S; Murty, B S

2008-08-01

Nanocrystalline p-type semiconductor copper aluminum oxide (CuAlO2) has been synthesized by mechanical alloying using freshly prepared Cu2O and alpha-AlO2O3 nanocrystals in toluene medium. A study on structural property performed with different alloying and post annealing durations, by X-ray diffraction (XRD) reveals the formation of single phase with average crystallite size approximately 45 nm. Optical absorbance onset at 364.5 nm confirms its wide band gap nature (E(g) = 3.4 eV) and the fluorescence emission behaviour (390 nm) confirms its direct band type transition. The activation energy for electrical conduction has been calculated by Arrhenius plots using impedance measurement. Both grain and grain boundary conductivity takes place with almost equal activation energies of approximately 0.45 eV. The paper discusses synthesis, structural, optical and electrical properties of delafossite CuAlO2 in detail.

Inverted Ultrathin Organic Solar Cells with a Quasi-Grating Structure for Efficient Carrier Collection and Dip-less Visible Optical Absorption.

PubMed

In, Sungjun; Park, Namkyoo

2016-02-23

We propose a metallic-particle-based two-dimensional quasi-grating structure for application to an organic solar cell. With the use of oblate spheroidal nanoparticles in contact with an anode of inverted, ultrathin organic solar cells (OSCs), the quasi-grating structure offers strong hybridization between localized surface plasmons and plasmonic gap modes leading to broadband (300~800 nm) and uniform (average ~90%) optical absorption spectra. Both strong optical enhancement in extreme confinement within the active layer (90 nm) and improved hole collection are thus realized. A coupled optical-electrical multi-physics optimization shows a large (~33%) enhancement in the optical absorption (corresponding to an absorption efficiency of ~47%, AM1.5G weighted, visible) when compared to a control OSC without the quasi-grating structure. That translates into a significant electrical performance gain of ~22% in short circuit current and ~15% in the power conversion efficiency (PCE), leading to an energy conversion efficiency (~6%) which is comparable to that of optically-thick inverted OSCs (3-7%). Detailed analysis on the influences of mode hybridization to optical field distributions, exciton generation rate, charge carrier collection efficiency and electrical conversion efficiency is provided, to offer an integrated understanding on the coupled optical-electrical optimization of ultrathin OSCs.

High-resolution non-contact measurement of the electrical activity of plants in situ using optical recording

PubMed Central

Zhao, Dong-Jie; Chen, Yang; Wang, Zi-Yang; Xue, Lin; Mao, Tong-Lin; Liu, Yi-Min; Wang, Zhong-Yi; Huang, Lan

2015-01-01

The limitations of conventional extracellular recording and intracellular recording make high-resolution multisite recording of plant bioelectrical activity in situ challenging. By combining a cooled charge-coupled device camera with a voltage-sensitive dye, we recorded the action potentials in the stem of Helianthus annuus and variation potentials at multiple sites simultaneously with high spatial resolution. The method of signal processing using coherence analysis was used to determine the synchronization of the selected signals. Our results provide direct visualization of the phloem, which is the distribution region of the electrical activities in the stem and leaf of H. annuus, and verify that the phloem is the main action potential transmission route in the stems of higher plants. Finally, the method of optical recording offers a unique opportunity to map the dynamic bioelectrical activity and provides an insight into the mechanisms of long-distance electrical signal transmission in higher plants. PMID:26333536

Electrically injected visible vertical cavity surface emitting laser diodes

DOEpatents

Schneider, Richard P.; Lott, James A.

1994-01-01

Visible laser light output from an electrically injected vertical cavity surface emitting laser (VSCEL) diode is enabled by the addition of phase-matching spacer layers on either side of the active region to form the optical cavity. The spacer layers comprise InAlP which act as charge carrier confinement means. Distributed Bragg reflector layers are formed on either side of the optical cavity to act as mirrors.

Electrically injected visible vertical cavity surface emitting laser diodes

DOEpatents

Schneider, R.P.; Lott, J.A.

1994-09-27

Visible laser light output from an electrically injected vertical cavity surface emitting laser (VSCEL) diode is enabled by the addition of phase-matching spacer layers on either side of the active region to form the optical cavity. The spacer layers comprise InAlP which act as charge carrier confinement means. Distributed Bragg reflector layers are formed on either side of the optical cavity to act as mirrors. 5 figs.

Design of "Eye Closure" system for the stealth of photo-electric equipments

NASA Astrophysics Data System (ADS)

Zhang, Y.; Hua, W. S.; Li, G.

2012-10-01

Based on the optical activity of liquid crystal, a new approach for the stealth of "cat's eye" targets is proposed in this paper. It imitates the physiological close reaction of human eyes when strong light irradiates eyes. With this approach, the "cat's eye" effect will vanish, which is applied in restricting photo-electric equipments being detected and located by active laser detection system. The structure and working principle of the design are presented. The drive circuit is given to control the optical switch automatically. Feasibility of this design is demonstrated by experimental method. The measured data illustrate that the proposed approach is effective to eliminate the "cat's eye" effect, so as to enhancing the viability of photo-electric equipments on the battlefield.

Electrically Conductive and Optically Active Porous Silicon Nanowires

PubMed Central

Qu, Yongquan; Liao, Lei; Li, Yujing; Zhang, Hua; Huang, Yu; Duan, Xiangfeng

2009-01-01

We report the synthesis of vertical silicon nanowire array through a two-step metal-assisted chemical etching of highly doped n-type silicon (100) wafers in a solution of hydrofluoric acid and hydrogen peroxide. The morphology of the as-grown silicon nanowires is tunable from solid nonporous nanowires, nonporous/nanoporous core/shell nanowires, and entirely nanoporous nanowires by controlling the hydrogen peroxide concentration in the etching solution. The porous silicon nanowires retain the single crystalline structure and crystallographic orientation of the starting silicon wafer, and are electrically conductive and optically active with visible photoluminescence. The combination of electronic and optical properties in the porous silicon nanowires may provide a platform for the novel optoelectronic devices for energy harvesting, conversion and biosensing. PMID:19807130

Optical waveguide device with an adiabatically-varying width

DOEpatents

Watts,; Michael R. , Nielson; Gregory, N [Albuquerque, NM

2011-05-10

Optical waveguide devices are disclosed which utilize an optical waveguide having a waveguide bend therein with a width that varies adiabatically between a minimum value and a maximum value of the width. One or more connecting members can be attached to the waveguide bend near the maximum value of the width thereof to support the waveguide bend or to supply electrical power to an impurity-doped region located within the waveguide bend near the maximum value of the width. The impurity-doped region can form an electrical heater or a semiconductor junction which can be activated with a voltage to provide a variable optical path length in the optical waveguide. The optical waveguide devices can be used to form a tunable interferometer (e.g. a Mach-Zehnder interferometer) which can be used for optical modulation or switching. The optical waveguide devices can also be used to form an optical delay line.

Surface enhanced Raman optical activity of molecules on orientationally averaged substrates: theory of electromagnetic effects.

PubMed

Janesko, Benjamin G; Scuseria, Gustavo E

2006-09-28

We present a model for electromagnetic enhancements in surface enhanced Raman optical activity (SEROA) spectroscopy. The model extends previous treatments of SEROA to substrates, such as metal nanoparticles in solution, that are orientationally averaged with respect to the laboratory frame. Our theoretical treatment combines analytical expressions for unenhanced Raman optical activity with molecular polarizability tensors that are dressed by the substrate's electromagnetic enhancements. We evaluate enhancements from model substrates to determine preliminary scaling laws and selection rules for SEROA. We find that dipolar substrates enhance Raman optical activity (ROA) scattering less than Raman scattering. Evanescent gradient contributions to orientationally averaged ROA scale to first or higher orders in the gradient of the incident plane-wave field. These evanescent gradient contributions may be large for substrates with quadrupolar responses to the plane-wave field gradient. Some substrates may also show a ROA contribution that depends only on the molecular electric dipole-electric dipole polarizability. These conclusions are illustrated via numerical calculations of surface enhanced Raman and ROA spectra from (R)-(-)-bromochlorofluoromethane on various model substrates.

Voltage-Sensitive Fluorescence of Indocyanine Green in the Heart

PubMed Central

Martišienė, Irma; Mačianskienė, Regina; Treinys, Rimantas; Navalinskas, Antanas; Almanaitytė, Mantė; Karčiauskas, Dainius; Kučinskas, Audrius; Grigalevičiūtė, Ramunė; Zigmantaitė, Vilma; Benetis, Rimantas; Jurevičius, Jonas

2016-01-01

So far, the optical mapping of cardiac electrical signals using voltage-sensitive fluorescent dyes has only been performed in experimental studies because these dyes are not yet approved for clinical use. It was recently reported that the well-known and widely used fluorescent dye indocyanine green (ICG), which has FDA approval, exhibits voltage sensitivity in various tissues, thus raising hopes that electrical activity could be optically mapped in the clinic. The aim of this study was to explore the possibility of using ICG to monitor cardiac electrical activity. Optical mapping experiments were performed on Langendorff rabbit hearts stained with ICG and perfused with electromechanical uncouplers. The residual contraction force and electrical action potentials were recorded simultaneously. Our research confirms that ICG is a voltage-sensitive dye with a dual-component (fast and slow) response to membrane potential changes. The fast component of the optical signal (OS) can have opposite polarities in different parts of the fluorescence spectrum. In contrast, the polarity of the slow component remains the same throughout the entire spectrum. Separating the OS into these components revealed two different voltage-sensitivity mechanisms for ICG. The fast component of the OS appears to be electrochromic in nature, whereas the slow component may arise from the redistribution of the dye molecules within or around the membrane. Both components quite accurately track the time of electrical signal propagation, but only the fast component is suitable for estimating the shape and duration of action potentials. Because ICG has voltage-sensitive properties in the entire heart, we suggest that it can be used to monitor cardiac electrical behavior in the clinic. PMID:26840736

Relationship between large horizontal electric fields and auroral arc elements

NASA Astrophysics Data System (ADS)

Lanchester, B. S.; Kailá, K.; McCrea, I. W.

1996-03-01

High time resolution optical measurements in the magnetic zenith are compared with European Incoherent Scatter (EISCAT) field-aligned measurements of electron density at 0.2-s resolution and with horizontal electric field measurements made at 278 km with resolution of 9 s. In one event, 20 min after a spectacular auroral breakup, a system of narrow and active arc elements moved southward into the magnetic zenith, where it remained for several minutes. During a 30-s interval of activity in a narrow arc element very close to the radar beam, the electric field vectors at 3-s resolution were found to be extremely large (up to 400 mVm-1) and to point toward the bright optical features in the arc, which moved along its length. It is proposed that the large electric fields are short-lived and are directly associated with the particle precipitation that causes the bright features in auroral arc elements.

Asymmetric photon transport in organic semiconductor nanowires through electrically controlled exciton diffusion

PubMed Central

Cui, Qiu Hong; Peng, Qian; Luo, Yi; Jiang, Yuqian; Yan, Yongli; Wei, Cong; Shuai, Zhigang; Sun, Cheng; Yao, Jiannian; Zhao, Yong Sheng

2018-01-01

The ability to steer the flow of light toward desired propagation directions is critically important for the realization of key functionalities in optical communication and information processing. Although various schemes have been proposed for this purpose, the lack of capability to incorporate an external electric field to effectively tune the light propagation has severely limited the on-chip integration of photonics and electronics. Because of the noninteractive nature of photons, it is only possible to electrically control the flow of light by modifying the refractive index of materials through the electro-optic effect. However, the weak optical effects need to be strongly amplified for practical applications in high-density photonic integrations. We show a new strategy that takes advantage of the strong exciton-photon coupling in active waveguides to effectively manipulate photon transport by controlling the interaction between excitons and the external electric field. Single-crystal organic semiconductor nanowires were used to generate highly stable Frenkel exciton polaritons with strong binding and diffusion abilities. By making use of directional exciton diffusion in an external electric field, we have realized an electrically driven asymmetric photon transport and thus directional light propagation in a single nanowire. With this new concept, we constructed a dual-output single wire–based device to build an electrically controlled single-pole double-throw optical switch with fast temporal response and high switching frequency. Our findings may lead to the innovation of concepts and device architectures for optical information processing. PMID:29556529

Electro-optical tunable birefringent filter

DOEpatents

Levinton, Fred M [Princeton, NJ

2012-01-31

An electrically tunable Lyot type filter is a Lyot that include one or more filter elements. Each filter element may have a planar, solid crystal comprised of a material that exhibits birefringence and is electro-optically active. Transparent electrodes may be coated on each face of the crystal. An input linear light polarizer may be located on one side of the crystal and oriented at 45 degrees to the optical axis of the birefringent crystal. An output linear light polarizer may be located on the other side of the crystal and oriented at -45 degrees with respect to the optical axis of the birefringent crystal. When an electric voltage is applied between the electrodes, the retardation of the crystal changes and so does the spectral transmission of the optical filter.

Hybrid Perovskite Phase Transition and Its Ionic, Electrical and Optical Properties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoque, Md Nadim Ferdous; Islam, Nazifah; Zhu, Kai

Hybrid perovskite solar cells (PSCs) under normal operation will reach a temperature above ~ 60 °C, across the tetragonal-cubic structural phase transition of methylammonium lead iodide (MAPbI 3). Whether the structural phase transition could result in dramatic changes of ionic, electrical and optical properties that may further impact the PSC performances should be studied. Herein, we report a structural phase transition temperature of MAPbI 3thin film at ~ 55 °C, but a striking contrast occurred at ~ 45 °C in the ionic and electrical properties of MAPbI 3due to a change of the ion activation energy from 0.7 eV tomore » 0.5 eV. The optical properties exhibited no sharp transition except for the steady increase of the bandgap with temperature. It was also observed that the activation energy for ionic migration steadily increased with increased grain sizes, and reduction of the grain boundary density reduced the ionic migration.« less

Optical and electrical properties of heavily indium-doped CdS around the semiconductor-metal phase transition

NASA Astrophysics Data System (ADS)

Broser, I.; Broser, R.; Birkicht, E.

1990-04-01

Heavily indium-doped CdS crystals are studied by comparing their optical and electrical properties. It is shown that in the near infrared spectral region for highly conducting crystals the correlation of electrical conductivity and optical effects can still be understood in the frame of the classical Drude-Lorentz model. Even for high doping the relaxation time τ and the effective mass m ∗ of the electrons are not markedly different from the room temperature values of "pure" crystals. At photon energies near the band gap, however, optical spectra in transmission, reflectivity, and emission show clearly the existence of band-tails and screening effects. A different situation holds for a highly compensated specimen: They are in a wide temperature region highly isolating, show activated photoconductivity and special structures in the optical spectra near the band gap. Their properties can be explained by assuming a meandering bandbending due to the combined action of donors and acceptors and the assumption of spatially isolated electron and hole droplets [6].

Bio-optical sensor for brain activity measurement based on whispering gallery modes

NASA Astrophysics Data System (ADS)

Ali, Amir R.; Massoud, Yasmin M.

2017-05-01

In this paper, a high-resolution bio-optical sensor is developed for brain activity measurement. The aim is to develop an optical sensor with enough sensitivity to detect small electric field perturbations caused by neuronal action potential. The sensing element is a polymeric dielectric micro-resonator fabricated in a spherical shape with a few hundred microns in diameter. They are made of optical quality polymers that are soft which make them mechanically compatible with tissue. The sensors are attached to or embedded in optical fibers which serve as input/output conduits for the sensors. Hundreds or even thousands of spheres can be attached to a single fiber to detect and transmit signals at different locations. The high quality factor for the optical resonator makes it significantly used in such bio-medical applications. The sensing phenomenon is based on whispering gallery modes (WGM) shifts of the optical sensor. To mimic the brain signals, the spherical resonator is immersed in a homogeneous electrical field that is created by applying potential difference across two metallic plates. One of the plates has a variable voltage while the volt on the other plate kept fixed. Any small perturbations of the potential difference (voltage) lead to change in the electric field intensity. In turn the sensor morphology will be affected due to the change in the electrostriction force acting on it causing change in its WGM. By tracking these WGM shift on the transmission spectrum, the induced potential difference (voltage change) could be measured. Results of a mathematical model simulation agree well with the preliminary experiments. Also, the results show that the brain activity could be measured using this principle.

Electrically driven hybrid photonic metamaterials for multifunctional control

NASA Astrophysics Data System (ADS)

Kang, Lei; Liu, Liu; Campbell, Sawyer D.; Yue, Taiwei; Ren, Qiang; Mayer, Theresa S.; Werner, Douglas H.

2017-08-01

The unique light-matter interaction in metamaterials, a type of artificial medium in which the geometrical features of subunits dominate their optical responses, have been utilized to achieve exotic material properties that are rare or nonexistent in natural materials. Furthermore, to extend their behaviors, active materials have been introduced into metamaterial systems to advance tunability, switchability and nonlinearity. Nevertheless, practical examples of versatile photonic metamaterials remain exceedingly rare for two main reasons. On the one hand, in sharp contrast to the broad material options available at lower frequencies, it is less common to find active media in the optical regime that can provide pronounced dielectric property changes under external stimuli, such as electric and magnetic fields. Vanadium dioxide (VO2), offering a large refractive index variation over a broad frequency range due to its near room temperature insulator-to-metal transition (IMT), has been favored in recent studies on tunable metamaterials. On the other hand, it turns out that regulating responses of hybrid metamaterials to external forces in an integrated manner is not a straightforward task. Recently, metamaterial-enabled devices (i.e., metadevices) with `self-sufficient' or `self-contained' electrical and optical properties have enabled complex functionalities. Here, we present a design methodology along with the associated experimental validation of a VO2 thin film integrated optical metamaterial absorber as a hybrid photonic platform for electrically driven multifunctional control, including reflectance switching, a rewritable memory process and manageable localized camouflage. The nanoengineered topologically continuous metal structure simultaneously supports the optical resonance and electrical functionality that actuates the phase transition in VO2 through the process of Joule heating. This work provides a universal approach to creating self-sufficient and highly-versatile nanophotonic systems.

Focal activation of primary visual cortex following supra-choroidal electrical stimulation of the retina: Intrinsic signal imaging and linear model analysis.

PubMed

Cloherty, Shaun L; Hietanen, Markus A; Suaning, Gregg J; Ibbotson, Michael R

2010-01-01

We performed optical intrinsic signal imaging of cat primary visual cortex (Area 17 and 18) while delivering bipolar electrical stimulation to the retina by way of a supra-choroidal electrode array. Using a general linear model (GLM) analysis we identified statistically significant (p < 0.01) activation in a localized region of cortex following supra-threshold electrical stimulation at a single retinal locus. (1) demonstrate that intrinsic signal imaging combined with linear model analysis provides a powerful tool for assessing cortical responses to prosthetic stimulation, and (2) confirm that supra-choroidal electrical stimulation can achieve localized activation of the cortex consistent with focal activation of the retina.

Label-free optical detection of action potential in mammalian neurons (Conference Presentation)

NASA Astrophysics Data System (ADS)

Batabyal, Subrata; Satpathy, Sarmishtha; Bui, Loan; Kim, Young-Tae; Mohanty, Samarendra K.; Davé, Digant P.

2017-02-01

Electrophysiology techniques are the gold standard in neuroscience for studying functionality of a single neuron to a complex neuronal network. However, electrophysiology techniques are not flawless, they are invasive nature, procedures are cumbersome to implement with limited capability of being used as a high-throughput recording system. Also, long term studies of neuronal functionality with aid of electrophysiology is not feasible. Non-invasive stimulation and detection of neuronal electrical activity has been a long standing goal in neuroscience. Introduction of optogenetics has ushered in the era of non-invasive optical stimulation of neurons, which is revolutionizing neuroscience research. Optical detection of neuronal activity that is comparable to electro-physiology is still elusive. A number of optical techniques have been reported recording of neuronal electrical activity but none is capable of reliably measuring action potential spikes that is comparable to electro-physiology. Optical detection of action potential with voltage sensitive fluorescent reporters are potential alternatives to electrophysiology techniques. The heavily rely on secondary reporters, which are often toxic in nature with background fluorescence, with slow response and low SNR making them far from ideal. The detection of one shot (without averaging)-single action potential in a true label-free way has been elusive so far. In this report, we demonstrate the optical detection of single neuronal spike in a cultured mammalian neuronal network without using any exogenous labels. To the best of our knowledge, this is the first demonstration of label free optical detection of single action potentials in a mammalian neuronal network, which was achieved using a high-speed phase sensitive interferometer. We have carried out stimulation and inhibition of neuronal firing using Glutamate and Tetrodotoxin respectively to demonstrate the different outcome (stimulation and inhibition) revealed in optical signal. We hypothesize that the interrogating optical beam is modulated during neuronal firing by electro-motility driven membrane fluctuation in conjunction with electrical wave propagation in cellular system.

Electrochromic-photovoltaic film for light-sensitive control of optical transmittance

DOEpatents

Branz, Howard M.; Crandall, Richard S.; Tracy, C. Edwin

1994-01-01

A variable transmittance optical component includes an electrochromic material and a photovoltaic device-type thin film solar cell deposited in a tandem type, monolithic single coating over the component. A bleed resistor of a predetermined value is connected in series across the electrochromic material and photovoltaic device controlling the activation and deactivation of the electrochromic material. The electrical conductivity between the electrochromic material and the photovoltaic device is enhanced by interposing a transparent electrically conductive layer.

Short cavity active mode locking fiber laser for optical sensing and imaging

NASA Astrophysics Data System (ADS)

Lee, Hwi Don; Han, Ga Hee; Jeong, Syung Won; Jeong, Myung Yung; Kim, Chang-Seok; Shin, Jun Geun; Lee, Byeong Ha; Eom, Tae Joong

2014-05-01

We demonstrate a highly linear wavenumber- swept active mode locking (AML) fiber laser for optical sensing and imaging without any wavenumber-space resampling process. In this all-electric AML wavenumber-swept mechanism, a conventional wavelength selection filter is eliminated and, instead, the suitable programmed electric modulation signal is directly applied to the gain medium. Various types of wavenumber (or wavelength) tunings can be implemented because of the filter-less cavity configuration. Therefore, we successfully demonstrate a linearly wavenumber-swept AML fiber laser with 26.5 mW of output power to obtain an in-vivo OCT image at the 100 kHz swept rate.

Effect of Se addition on optical and electrical properties of chalcogenide CdSSe thin films

NASA Astrophysics Data System (ADS)

Hassanien, A. S.; Akl, Alaa A.

2016-01-01

Compositional dependence of optical and electrical properties of chalcogenide CdSxSe1-x (0.4 ≥ x ≥ 0.0 at. %) thin films was studied. Cadmium sulphoselenide films were deposited by thermal evaporation technique at vacuum (8.2 × 10-4 Pa) onto preheated glass substrates (523 K). The evaporation rate and film thickness were kept constant at 2.50 nm/s and 375 ± 5 nm, respectively. X-ray diffractograms showed that, the deposited films have the low crystalline nature. Energy dispersive analysis by X-ray (EDAX) was used to check the compositional elements of deposited films. The absorption coefficient was determined from transmission and reflection measurements at room temperature in the wavelength range 300-2500 nm. Optical density, skin depth, optical energy gap and Urbach's parameters of CdSSe thin films have also been estimated. The direct optical energy gap decreased from 2.248 eV to 1.749 eV when the ratio of Se-content was increased from 0.60 to 1.00 . Conduction band and valance band positions were evaluated. The temperature dependence of dc-electrical resistivity in the temperature range (293-450 K) has been reported. Three conduction regions due to different conduction mechanisms were detected. Electrical sheet resistance, activation energy and pre-exponential parameters were discussed. The estimated values of optical and electrical parameters were strongly dependent upon the Se-content in CdSSe matrix.

Non-contact measurement of electrical activity in neurons using magnified image spatial spectrum (MISS) microscopy (Conference Presentation)

NASA Astrophysics Data System (ADS)

Majeed, Hassaan; Lee, Young J.; Best-Popescu, Catherine; Popescu, Gabriel; Jang, Sung-Soo; Chung, Hee Jung

2017-02-01

Traditionally the measurement of electrical activity in neurons has been carried out using microelectrode arrays that require the conducting elements to be in contact with the neuronal network. This method, also referred to as "electrophysiology", while being excellent in terms of temporal resolution is limited in spatial resolution and is invasive. An optical microscopy method for measuring electrical activity is thus highly desired. Common-path quantitative phase imaging (QPI) systems are good candidates for such investigations as they provide high sensitivity (on the order of nanometers) to the plasma membrane fluctuations that can be linked to electrical activity in a neuronal circuit. In this work we measured electrical activity in a culture of rat cortical neurons using MISS microscopy, a high-speed common-path QPI technique having an axial resolution of around 1 nm in optical path-length, which we introduced at PW BIOS 2016. Specifically, we measured the vesicular cycling (endocytosis and exocytosis) occurring at axon terminals of the neurons due to electrical activity caused by adding a high K+ solution to the cell culture. The axon terminals were localized using a micro-fluidic device that separated them from the rest of the culture. Stacks of images of these terminals were acquired at 826 fps both before and after K+ excitation and the temporal standard deviation maps for the two cases were compared to measure the membrane fluctuations. Concurrently, the existence of vesicular cycling was confirmed through fluorescent tagging and imaging of the vesicles at and around the axon terminals.

Electrochromic-photovoltaic film for light-sensitive control of optical transmittance

DOEpatents

Branz, H.M.; Crandall, R.S.; Tracy, C.E.

1994-12-27

A variable transmittance optical component includes an electrochromic material and a photovoltaic device-type thin film solar cell deposited in a tandem type, monolithic single coating over the component. A bleed resistor of a predetermined value is connected in series across the electrochromic material and photovoltaic device controlling the activation and deactivation of the electrochromic material. The electrical conductivity between the electrochromic material and the photovoltaic device is enhanced by interposing a transparent electrically conductive layer. 5 figures.

Monolithic interconnected module with a tunnel junction for enhanced electrical and optical performance

DOEpatents

Murray, Christopher S.; Wilt, David M.

2000-01-01

An improved thermophotovoltaic (TPV) n/p/n device is provided. Monolithic Interconnected Modules (MIMS), semiconductor devices converting infrared radiation to electricity, have been developed with improved electrical and optical performance. The structure is an n-type emitter on a p-type base with an n-type lateral conduction layer. The incorporation of a tunnel junction and the reduction in the amount of p-type material used results in negligible parasitic absorption, decreased series resistance, increased voltage and increased active area. The novel use of a tunnel junction results in the potential for a TPV device with efficiency greater than 24%.

Genetically Targeted All-Optical Electrophysiology with a Transgenic Cre-Dependent Optopatch Mouse

PubMed Central

Lou, Shan; Adam, Yoav; Weinstein, Eli N.; Williams, Erika; Williams, Katherine; Parot, Vicente; Kavokine, Nikita; Liberles, Stephen; Madisen, Linda; Zeng, Hongkui

2016-01-01

Recent advances in optogenetics have enabled simultaneous optical perturbation and optical readout of membrane potential in diverse cell types. Here, we develop and characterize a Cre-dependent transgenic Optopatch2 mouse line that we call Floxopatch. The animals expressed a blue-shifted channelrhodopsin, CheRiff, and a near infrared Archaerhodopsin-derived voltage indicator, QuasAr2, via targeted knock-in at the rosa26 locus. In Optopatch-expressing animals, we tested for overall health, genetically targeted expression, and function of the optogenetic components. In offspring of Floxopatch mice crossed with a variety of Cre driver lines, we observed spontaneous and optically evoked activity in vitro in acute brain slices and in vivo in somatosensory ganglia. Cell-type-specific expression allowed classification and characterization of neuronal subtypes based on their firing patterns. The Floxopatch mouse line is a useful tool for fast and sensitive characterization of neural activity in genetically specified cell types in intact tissue. SIGNIFICANCE STATEMENT Optical recordings of neural activity offer the promise of rapid and spatially resolved mapping of neural function. Calcium imaging has been widely applied in this mode, but is insensitive to the details of action potential waveforms and subthreshold events. Simultaneous optical perturbation and optical readout of single-cell electrical activity (“Optopatch”) has been demonstrated in cultured neurons and in organotypic brain slices, but not in acute brain slices or in vivo. Here, we describe a transgenic mouse in which expression of Optopatch constructs is controlled by the Cre-recombinase enzyme. This animal enables fast and robust optical measurements of single-cell electrical excitability in acute brain slices and in somatosensory ganglia in vivo, opening the door to rapid optical mapping of neuronal excitability. PMID:27798186

Effect of annealing on structural, electrical and optical properties of p-quaterphenyl thin films

NASA Astrophysics Data System (ADS)

Darwish, A. A. A.

2017-05-01

Thin films of p-quaterphenyl are deposited by an evaporation technique. IR spectra confirm that the thermal evaporation method is a decent one to acquire p-quaterphenyl films without dissociation. The X-ray diffraction studies demonstrate that the as-deposited and annealed films are polycrystalline with monoclinic structure. The electrical conductivity shows an activated behavior and indicating that p-quaterphenyl behaves as an organic semiconductor. The value of activation energy decreases by annealing, which explains due to the adjustment in the crystallite size. Optical properties of p-quaterphenyl films were performed to determine some optical constants. Dispersion of the refractive index is described utilizing the Wemple-DiDomenico model. In addition, the third order nonlinear susceptibility and the nonlinear refractive index are calculated. The analysis of the absorption coefficient for the as-deposited film showed an allowed direct optical band gap with a value of 2.35 eV, which decreased by annealing to 2.05 eV.

Self-Latching Piezocomposite Actuator

NASA Technical Reports Server (NTRS)

Wilkie, William K. (Inventor); Lynch, Christopher S. (Inventor); Bryant, Robert G. (Inventor)

2017-01-01

A self-latching piezocomposite actuator includes a plurality of shape memory ceramic fibers. The actuator can be latched by applying an electrical field to the shape memory ceramic fibers. The actuator remains in a latched state/shape after the electrical field is no longer present. A reverse polarity electric field may be applied to reset the actuator to its unlatched state/shape. Applied electric fields may be utilized to provide a plurality of latch states between the latched and unlatched states of the actuator. The self-latching piezocomposite actuator can be used for active/adaptive airfoils having variable camber, trim tabs, active/deformable engine inlets, adaptive or adjustable vortex generators, active optical components such as mirrors that change shapes, and other morphing structures.

Optical and electrical characterizations of multifunctional silver phosphate glass and polymer-based optical fibers.

PubMed

Rioux, Maxime; Ledemi, Yannick; Morency, Steeve; de Lima Filho, Elton Soares; Messaddeq, Younès

2017-03-03

In recent years, the fabrication of multifunctional fibers has expanded for multiple applications that require the transmission of both light and electricity. Fibers featuring these two properties are usually composed either of a single material that supports the different characteristics or of a combination of different materials. In this work, we fabricated (i) novel single-core step-index optical fibers made of electrically conductive AgI-AgPO 3 -WO 3 glass and (ii) novel multimaterial fibers with different designs made of AgI-AgPO 3 -WO 3 glass and optically transparent polycarbonate and poly (methyl methacrylate) polymers. The multifunctional fibers produced show light transmission over a wide range of wavelengths from 500 to 1000 nm for the single-core fibers and from 400 to 1000 nm for the multimaterial fibers. Furthermore, these fibers showed excellent electrical conductivity with values ranging between 10 -3 and 10 -1  S·cm -1 at room temperature within the range of AC frequencies from 1 Hz to 1 MHz. Multimodal taper-tipped fibre microprobes were then fabricated and were characterized. This advanced design could provide promising tools for in vivo electrophysiological experiments that require light delivery through an optical core in addition to neuronal activity recording.

Optical and electrical characterizations of multifunctional silver phosphate glass and polymer-based optical fibers

PubMed Central

Rioux, Maxime; Ledemi, Yannick; Morency, Steeve; de Lima Filho, Elton Soares; Messaddeq, Younès

2017-01-01

In recent years, the fabrication of multifunctional fibers has expanded for multiple applications that require the transmission of both light and electricity. Fibers featuring these two properties are usually composed either of a single material that supports the different characteristics or of a combination of different materials. In this work, we fabricated (i) novel single-core step-index optical fibers made of electrically conductive AgI-AgPO3-WO3 glass and (ii) novel multimaterial fibers with different designs made of AgI-AgPO3-WO3 glass and optically transparent polycarbonate and poly (methyl methacrylate) polymers. The multifunctional fibers produced show light transmission over a wide range of wavelengths from 500 to 1000 nm for the single-core fibers and from 400 to 1000 nm for the multimaterial fibers. Furthermore, these fibers showed excellent electrical conductivity with values ranging between 10−3 and 10−1 S·cm−1 at room temperature within the range of AC frequencies from 1 Hz to 1 MHz. Multimodal taper-tipped fibre microprobes were then fabricated and were characterized. This advanced design could provide promising tools for in vivo electrophysiological experiments that require light delivery through an optical core in addition to neuronal activity recording. PMID:28256608

Optical impedance spectroscopy with single-mode electro-active-integrated optical waveguides.

PubMed

Han, Xue; Mendes, Sergio B

2014-02-04

An optical impedance spectroscopy (OIS) technique based on a single-mode electro-active-integrated optical waveguide (EA-IOW) was developed to investigate electron-transfer processes of redox adsorbates. A highly sensitive single-mode EA-IOW device was used to optically follow the time-dependent faradaic current originated from a submonolayer of cytochrome c undergoing redox exchanges driven by a harmonic modulation of the electric potential at several dc bias potentials and at several frequencies. To properly retrieve the faradaic current density from the ac-modulated optical signal, we introduce here a mathematical formalism that (i) accounts for intrinsic changes that invariably occur in the optical baseline of the EA-IOW device during potential modulation and (ii) provides accurate results for the electro-chemical parameters. We are able to optically reconstruct the faradaic current density profile against the dc bias potential in the working electrode, identify the formal potential, and determine the energy-width of the electron-transfer process. In addition, by combining the optically reconstructed faradaic signal with simple electrical measurements of impedance across the whole electrochemical cell and the capacitance of the electric double-layer, we are able to determine the time-constant connected to the redox reaction of the adsorbed protein assembly. For cytochrome c directly immobilized onto the indium tin oxide (ITO) surface, we measured a reaction rate constant of 26.5 s(-1). Finally, we calculate the charge-transfer resistance and pseudocapacitance associated with the electron-transfer process and show that the frequency dependence of the redox reaction of the protein submonolayer follows as expected the electrical equivalent of an RC-series admittance diagram. Above all, we show here that OIS with single-mode EA-IOW's provide strong analytical signals that can be readily monitored even for small surface-densities of species involved in the redox process (e.g., fmol/cm(2), 0.1% of a full protein monolayer). This experimental approach, when combined with the analytical formalism described here, brings additional sensitivity, accuracy, and simplicity to electro-chemical analysis and is expected to become a useful tool in investigations of redox processes.

Optically powered active sensing system for Internet Of Things

NASA Astrophysics Data System (ADS)

Gao, Chen; Wang, Jin; Yin, Long; Yang, Jing; Jiang, Jian; Wan, Hongdan

2014-10-01

Internet Of Things (IOT) drives a significant increase in the extent and type of sensing technology and equipment. Sensors, instrumentation, control electronics, data logging and transmission units comprising such sensing systems will all require to be powered. Conventionally, electrical powering is supplied by batteries or/and electric power cables. The power supply by batteries usually has a limited lifetime, while the electric power cables are susceptible to electromagnetic interference. In fact, the electromagnetic interference is the key issue limiting the power supply in the strong electromagnetic radiation area and other extreme environments. The novel alternative method of power supply is power over fiber (PoF) technique. As fibers are used as power supply lines instead, the delivery of the power is inherently immune to electromagnetic radiation, and avoids cumbersome shielding of power lines. Such a safer power supply mode would be a promising candidate for applications in IOT. In this work, we built up optically powered active sensing system, supplying uninterrupted power for the remote active sensors and communication modules. Also, we proposed a novel maximum power point tracking technique for photovoltaic power convertors. In our system, the actual output efficiency greater than 40% within 1W laser power. After 1km fiber transmission and opto-electric power conversion, a stable electric power of 210mW was obtained, which is sufficient for operating an active sensing system.

Electrical Tuning of Exciton-Plasmon Polariton Coupling in Monolayer MoS2 Integrated with Plasmonic Nanoantenna Lattice.

PubMed

Lee, Bumsu; Liu, Wenjing; Naylor, Carl H; Park, Joohee; Malek, Stephanie C; Berger, Jacob S; Johnson, A T Charlie; Agarwal, Ritesh

2017-07-12

Active control of light-matter interactions in semiconductors is critical for realizing next generation optoelectronic devices with real-time control of the system's optical properties and hence functionalities via external fields. The ability to dynamically manipulate optical interactions by applied fields in active materials coupled to cavities with fixed geometrical parameters opens up possibilities of controlling the lifetimes, oscillator strengths, effective mass, and relaxation properties of a coupled exciton-photon (or plasmon) system. Here, we demonstrate electrical control of exciton-plasmon coupling strengths between strong and weak coupling limits in a two-dimensional semiconductor integrated with plasmonic nanoresonators assembled in a field-effect transistor device by electrostatic doping. As a result, the energy-momentum dispersions of such an exciton-plasmon coupled system can be altered dynamically with applied electric field by modulating the excitonic properties of monolayer MoS 2 arising from many-body effects. In addition, evidence of enhanced coupling between charged excitons (trions) and plasmons was also observed upon increased carrier injection, which can be utilized for fabricating Fermionic polaritonic and magnetoplasmonic devices. The ability to dynamically control the optical properties of a coupled exciton-plasmonic system with electric fields demonstrates the versatility of the coupled system and offers a new platform for the design of optoelectronic devices with precisely tailored responses.

Characterization of plasmonic hole arrays as transparent electrical contacts for organic photovoltaics using high-brightness Fourier transform methods

DOE PAGES

Camino, Fernando E.; Nam, Chang-Yong; Pang, Yutong T.; ...

2014-05-15

Here we present a methodology for probing light-matter interactions in prototype photovoltaic devices consisting of an organic semiconductor active layer with a semitransparent metal electrical contact exhibiting surface plasmon-based enhanced optical transmission. We achieve high-spectral irradiance in a spot size of less than 100 μm using a high-brightness laser-driven light source and appropriate coupling optics. Spatially resolved Fourier transform photocurrent spectroscopy in the visible and near-infrared spectral regions allows us to measure external quantum efficiency with high sensitivity in small-area devices (<1 mm 2). Lastly, this allows for rapid fabrication of variable-pitch sub-wavelength hole arrays in metal films for usemore » as transparent electrical contacts, and evaluation of the evanescent and propagating mode coupling to resonances in the active layer.« less

Electrically switchable polymer liquid crystal and polymer birefringent flake in fluid host systems and optical devices utilizing same

DOEpatents

Marshall, Kenneth L.; Kosc, Tanya Z.; Jacobs, Stephen D.; Faris, Sadeg M.; Li, Le

2003-12-16

Flakes or platelets of polymer liquid crystals (PLC) or other birefringent polymers (BP) suspended in a fluid host medium constitute a system that can function as the active element in an electrically switchable optical device when the suspension is either contained between a pair of rigid substrates bearing transparent conductive coatings or dispersed as microcapsules within the body of a flexible host polymer. Optical properties of these flake materials include large effective optical path length, different polarization states and high angular sensitivity in their selective reflection or birefringence. The flakes or platelets of these devices need only a 3-20.degree. rotation about the normal to the cell surface to achieve switching characteristics obtainable with prior devices using particle rotation or translation.

Novel hybrid III:V concentrator photovoltaic-thermoelectric receiver designs

NASA Astrophysics Data System (ADS)

Sweet, Tracy K. N.; Rolley, Matthew H.; Prest, Martin J.; Min, Gao

2017-09-01

This paper presents the design, manufacture and electrical characterization of novel hybrid III:V Concentrator Photovoltaic-Thermoelectric receivers. Addition of an encapsulating and spectral homogenizing single active surface secondary optic lens increased the solar cell electrical power output from 7.66mW (ALPHA no cooling) to 18.20mW (KAPPA with TE cooling). The effective optical concentration of the optics, based on short circuit current, was x2.4. A linear irradiance vs maximum power receiver output relationship was observed (R2=0.9978), confirming good optical alignment during manufacture and likewise internal current matching of the series-connected triple-junction cell. An in-depth COMSOL model for simulated evaluation of the synergistic thermally-dependent parameters inherent to hybrid devices was built and experimentally validated.

Effect of 50MeV Li{sup 3+} ion irradiation on structural, optical and electrical properties of amorphous Se{sub 95}Zn{sub 5} thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahmad, Shabir, E-mail: shaphyjmi@gmail.com; Sethi, Riti; Nasir, Mohd

2015-08-28

Present work focuses on the effect of swift heavy ion (SHI) irradiation of 50MeV Li{sup 3+} ions by varying the fluencies in the range of 1×10{sup 12} to 5×10{sup 13} ions/cm{sup 2} on the morphological, structural, optical and electrical properties of amorphous Se{sub 95}Zn{sub 5} thin films. Thin films of ~250nm thickness were deposited on cleaned glass substrates by thermal evaporation technique. X-ray diffraction (XRD) analysis shows the pristine thin film of Se{sub 95}Zn{sub 5} growsin hexagonal phase structure. Also it was found that the small peak observed in XRD spectra vanishes after SHI irradiation indicates the defects of themore » material increases. The optical parameters: absorption coefficient (α), extinction coefficient (K), refractive index (n) optical band gap (E{sub g}) and Urbach’s energy (E{sub U}) are determined from optical absorption spectra data measured from spectrophotometry in the wavelength range 200-1000nm. It was found that the values of absorption coefficient, refractive index and extinction coefficient increases while the value optical band gap decreases with the increase of ion fluence. This post irradiation change in the optical parameters was interpreted in terms of bond distribution model. Electrical properties such as dc conductivity and temperature dependent photoconductivity of investigated thin films were carried out in the temperature range 309-370 K. Analysis of data shows activation energy of dark current is greater as compared to activation energy photocurrent. The value of activation energy decreases with the increase of ion fluence indicates that the defect density of states increases.Also it was found that the value of dc conductivity and photoconductivity increases with the increase of ion fluence.« less

Electrical and Optical Enhancement in Internally Nanopatterned Organic Light-Emitting Diodes

NASA Astrophysics Data System (ADS)

Fina, Michael Dane

Organic light-emitting diodes (OLEDs) have made tremendous technological progress in the past two decades and have emerged as a top competitor for next generation light-emitting displays and lighting. State-of-the-art OLEDs have been reported in literature to approach, and even surpass, white fluorescent tube efficiency. However, despite rapid technological progress, efficiency metrics must be improved to compete with traditional inorganic light-emitting diode (LED) technology. Organic materials possess specialized traits that permit manipulations to the light-emitting cavity. Overall, as demonstrated within, these modifications can be used to improve electrical and optical device efficiencies. This work is focused at analyzing the effects that nanopatterned geometric modifications to the organic active layers play on device efficiency. In general, OLED efficiency is complicated by the complex, coupled processes which contribute to spontaneous dipole emission. A composite of three sub-systems (electrical, exciton and optical) ultimately dictate the OLED device efficiency. OLED electrical operation is believed to take place via a low-mobility-modified Schottky injection process. In the injection-limited regime, geometric effects are expected to modify the local electric field leading to device current enhancement. It is shown that the patterning effect can be used to enhance charge carrier parity, thereby enhancing overall recombination. Current density and luminance characteristics are shown to be improved by OLED nanopatterning from both the model developed within and experimental techniques. Next, the optical enhancement effects produced by the nanopatterned array are considered. Finite-difference time-domain (FDTD) simulations are used to determine positional, spectral optical enhancement for the nanopatterned device. The results show beneficial effects to the device performance. The optical enhancements are related to the reduction in internal radiative quenching (improved internal quantum efficiency) and improvement in light extraction (improved outcoupling efficiency). Furthermore, the electrical model is used to construct a positional radiative efficiency map that when combined with the optical enhancement reveals the overall external quantum efficiency enhancement.

Depth-Dependent Defect Studies Using Coherent Acoustic Phonons

DTIC Science & Technology

2014-09-29

using CAP waves as an active moving interface to induce local changes in electric, acoustic , and optical properties. This is able to generate ultrafast...the elastic strain component [6]. b) Modification of the crystal lattice due to transient strain caused by the coherent acoustic phonon wave . The...opto-electronic properties of materials. We are also using CAP waves as an active moving interface to induce local changes in electric, acoustic , and

Semiconductor light source with electrically tunable emission wavelength

DOEpatents

Belenky, Gregory [Port Jefferson, NY; Bruno, John D [Bowie, MD; Kisin, Mikhail V [Centereach, NY; Luryi, Serge [Setauket, NY; Shterengas, Leon [Centereach, NY; Suchalkin, Sergey [Centereach, NY; Tober, Richard L [Elkridge, MD

2011-01-25

A semiconductor light source comprises a substrate, lower and upper claddings, a waveguide region with imbedded active area, and electrical contacts to provide voltage necessary for the wavelength tuning. The active region includes single or several heterojunction periods sandwiched between charge accumulation layers. Each of the active region periods comprises higher and lower affinity semiconductor layers with type-II band alignment. The charge carrier accumulation in the charge accumulation layers results in electric field build-up and leads to the formation of generally triangular electron and hole potential wells in the higher and lower affinity layers. Nonequillibrium carriers can be created in the active region by means of electrical injection or optical pumping. The ground state energy in the triangular wells and the radiation wavelength can be tuned by changing the voltage drop across the active region.

Sub-μrad laser beam tracking

NASA Astrophysics Data System (ADS)

Buske, Ivo; Riede, Wolfgang

2006-09-01

We compare active optical elements based on different technologies to accomplish the requirements of a 2-dim. fine tracking control system. A cascaded optically and electrically addressable spatial light modulator (OASLM) based on liquid crystals (LC) is used for refractive beam steering. Spatial light modulators provide a controllable phase wedge to generate a beam deflection. Additionally, a tip/tilt mirror approach operating with piezo-electric actuators is investigated. A digital PID controller is implemented for closed-loop control. Beam tracking with a root-mean-squared accuracy of Δα=30 nrad has been laboratory-confirmed.

Electro-optic sampling of near-infrared waveforms

NASA Astrophysics Data System (ADS)

Keiber, Sabine; Sederberg, Shawn; Schwarz, Alexander; Trubetskov, Michael; Pervak, Volodymyr; Krausz, Ferenc; Karpowicz, Nicholas

2016-03-01

Access to the complete electric field evolution of a laser pulse is essential for attosecond science in general, and for the scrutiny and control of electron phenomena in solid-state physics specifically. Time-resolved field measurements are routine in the terahertz spectral range, using electro-optic sampling (EOS), photoconductive switches and field-induced second harmonic generation. EOS in particular features outstanding sensitivity and ease of use, making it the basis of time-resolved spectroscopic measurements for studying charge carrier dynamics and active optical devices. In this Letter, we show that careful optical filtering allows the bandwidth of this technique to be extended to wavelengths as short as 1.2 μm (230 THz) with half-cycle durations 2.3 times shorter than the sampling pulse. In a proof-of-principle application, we measure the influence of optical parametric amplification (OPA) on the electric field dynamics of a few-cycle near-infrared (NIR) pulse.

Structural symmetry breaking of silicon containing polymers and their relation with electrical conductivity and Raman active vibrations

NASA Astrophysics Data System (ADS)

Cabrera, Alejandro; González, Carmen; Tagle, Luis; Terraza, Claudio; Volkmann, Ulrich; Barriga, Andrés; Ramos, Esteban; Pavez, Maximiliano

2011-03-01

The incorporation of silicon into the polymeric main chain or side groups can provide an enhancement in chemical, physical and mechanical properties. We report an efficient method for the synthesis of polymers containing silicon in the main chain, from the polycondensation reactions of four optically active carboxylic diacid. The solubility of the polymers, the molecular weight, the glass transition and the thermal stability were studied by standard techniques. Raman spectroscopy was used to probe the conformation of stretching modes as function of the temperature. The conductivity measurements indicated that the alignment of the molecules is a crucial parameter for electrical performance. When the polymers were exposed to iodine, charge transfer increased their mobility and decreased their optical band gaps. These novel properties highlight the possibility to generate alternative active opto-electronics polymers.

Extraction of natural weight shift and foot rolling in gait based on hetero-core optical fiber load sensor

NASA Astrophysics Data System (ADS)

Otsuka, Yudai; Koyama, Yuya; Nishiyama, Michiko; Watanabe, Kazuhiro

2016-03-01

Gait in daily activity affects human health because it may cause physical problems such as asymmetric pelvis, flat foot and bowlegs. Monitoring natural weight shift and foot rolling on plantar has been employed in order for researchers to analyze gait characteristics. Conventional gait monitoring systems have been developed using camera, acceleration sensor, gyro sensor and electrical load sensors. They have some problems such as limited measurement place, temperature dependence and electric leakage. On the other hand, a hetero-core optical fiber sensor has many advantages such as high sensitivity for macro-bending, light weight sensor element, independency on temperature fluctuations, and no electric contact. This paper describes extraction of natural weight shift and foot rolling for gait evaluation by using a sensitive shoe, in the insole of which hetero-core optical load sensors are embedded for detecting plantar pressure. Plantar pressure of three subjects who wear the sensitive shoe and walk on the treadmill was monitored. As a result, weight shift and foot rolling for three subjects were extracted using the proposed sensitive shoe in terms of centroid movement and positions. Additionally, these extracted data are compared to that of electric load sensor to ensure consistency. For these results, it was successfully demonstrated that hetero-core optical fiber load sensor performed in unconstraint gait monitoring as well as electric load sensor.

Optical mapping of optogenetically shaped cardiac action potentials.

PubMed

Park, Sarah A; Lee, Shin-Rong; Tung, Leslie; Yue, David T

2014-08-19

Light-mediated silencing and stimulation of cardiac excitability, an important complement to electrical stimulation, promises important discoveries and therapies. To date, cardiac optogenetics has been studied with patch-clamp, multielectrode arrays, video microscopy, and an all-optical system measuring calcium transients. The future lies in achieving simultaneous optical acquisition of excitability signals and optogenetic control, both with high spatio-temporal resolution. Here, we make progress by combining optical mapping of action potentials with concurrent activation of channelrhodopsin-2 (ChR2) or halorhodopsin (eNpHR3.0), via an all-optical system applied to monolayers of neonatal rat ventricular myocytes (NRVM). Additionally, we explore the capability of ChR2 and eNpHR3.0 to shape action-potential waveforms, potentially aiding the study of short/long QT syndromes that result from abnormal changes in action potential duration (APD). These results show the promise of an all-optical system to acquire action potentials with precise temporal optogenetics control, achieving a long-sought flexibility beyond the means of conventional electrical stimulation.

Optical mapping of optogenetically shaped cardiac action potentials

PubMed Central

Park, Sarah A.; Lee, Shin-Rong; Tung, Leslie; Yue, David T.

2014-01-01

Light-mediated silencing and stimulation of cardiac excitability, an important complement to electrical stimulation, promises important discoveries and therapies. To date, cardiac optogenetics has been studied with patch-clamp, multielectrode arrays, video microscopy, and an all-optical system measuring calcium transients. The future lies in achieving simultaneous optical acquisition of excitability signals and optogenetic control, both with high spatio-temporal resolution. Here, we make progress by combining optical mapping of action potentials with concurrent activation of channelrhodopsin-2 (ChR2) or halorhodopsin (eNpHR3.0), via an all-optical system applied to monolayers of neonatal rat ventricular myocytes (NRVM). Additionally, we explore the capability of ChR2 and eNpHR3.0 to shape action-potential waveforms, potentially aiding the study of short/long QT syndromes that result from abnormal changes in action potential duration (APD). These results show the promise of an all-optical system to acquire action potentials with precise temporal optogenetics control, achieving a long-sought flexibility beyond the means of conventional electrical stimulation. PMID:25135113

Micro-optics technology and sensor systems applications

NASA Technical Reports Server (NTRS)

Gal, George; Herman, B.; Anderson, W.; Whitney, R.; Morrow, H.

1993-01-01

The current generation of electro-optical sensors utilizing refractive and reflective optical elements require sophisticated, complex, and expensive designs. Advanced-technology-based electro-optical sensors of minimum size and weight require miniaturization of optical, electrical, and mechanical devices with an increasing trend toward integration of various components. Micro-optics technology has the potential in a number of areas to simplify optical design with improved performance. This includes internally cooled apertures, hybrid optical design, microlenses, dispersive multicolor microlenses, active dither, electronically controlled optical beam steer, and microscopic integration of micro-optics, detectors, and signal processing layers. This paper describes our approach to the development of micro-optics technology with our main emphasis for sensors applications.

Impact of nucleation of carbonaceous clusters on structural, electrical and optical properties of Cr+-implanted PMMA

NASA Astrophysics Data System (ADS)

Arif, Shafaq; Rafique, M. Shahid; Saleemi, Farhat; Naab, Fabian; Toader, Ovidiu; Mahmood, Arshad; Aziz, Uzma

2016-09-01

Specimens of polymethylmethacrylate (PMMA) have been implanted with 400 keV Cr+ ions at different ion fluences ranging from 5 × 1013 to 5 × 1015 ions/cm2. The possible chemical reactions involved in the nucleation of conjugated carbonaceous clusters in implanted PMMA are discussed. Furthermore, impact of formation of carbonaceous clusters on structural, optical, electrical and morphological properties of implanted PMMA has been examined. The structural modifications in implanted PMMA are observed by Raman spectroscopy. The variation in optical band gap and Urbach energy is measured using UV-visible spectroscopic analysis. The effects of Cr+ ion implantation on electrical and morphological properties are investigated by four-probe apparatus and atomic force microscopy, respectively. The Raman spectroscopic analysis confirmed the formation of carbonaceous clusters with the transformation of implanted layer of PMMA into amorphous carbon. Simultaneously, the optical band gap of implanted PMMA has reduced from 3.13 to 0.85 eV. The increase in Urbach energy favors the decline in band gap together with the structural modification in implanted PMMA. As a result of Cr+ ion implantation, the electrical conductivity of PMMA has improved from 2.14 ± 0.06 × 10-10 S/cm (pristine) to 7.20 ± 0.36 × 10-6 S/cm. The AFM images revealed a decrease in surface roughness with an increment in ion fluence up to 5 × 1014 ions/cm2. The modification in the electrical, optical and structural properties makes the PMMA a promising candidate for its future utilization, as a semiconducting and optically active material, in various fields like plastic electronics and optoelectronic devices.

Scalable, high-capacity optical switches for Internet routers and moving platforms

NASA Astrophysics Data System (ADS)

Joe, In-Sung

Internet traffic nearly doubles every year, and we need faster routers with higher ports count, yet lower electrical power consumption. Current internet routers use electrical switches that consume large amounts of electrical power to operate at high data rates. These internet routers dissipate ˜ 10kW per rack, and their capacity is limited by cooling constraints. The power consumption is also critical for moving platforms. As avionics advance, the demand for larger capacity networks increases. Optical fibers are already chosen for high speed data transmission in advanced aircraft. In optical communication systems, integrated passive optical components, such as Array Waveguide Gratings (AWGs), have provided larger capacity with lower power consumption, because minimal electrical power is required for their operation. In addition, compact, wavelength-tunable semiconductor lasers with wide tuning ranges that can switch their wavelengths in tens of nanoseconds have been demonstrated. Here we present a wavelength-selective optical packet switch based on Waveguide Grating Routers (WGRs), passive splitters, and combiners. Tunable lasers on the transmitter side are the only active switching elements. The WGR is operated on multiple Free Spectral Ranges (FSRs) to achieve increased port count and switching capacity while maintaining strict-sense, non-blocking operation. Switching times of less than 24ns between two wavelengths covering three FSRs is demonstrated experimentally. The electrical power consumption, size, weight, and cost of our optical switch is compared with those of conventional electrical switches, showing substantial improvements at large throughputs (˜2 Tb/s full duplex). A revised switch design that does not suffer optical loss from star couplers is proposed. This switch design uses only WGRs, and it is suitable for networks with stringent power budgets. The burst nature of the optical packet transmission requires clock recovery for every incoming packet, and conventional continuous-mode receivers are not suitable for this application. An Embedded Clock Transport (ECT) technique is adopted here. The ECT combines a clock tone with the data payload before the transmission. Simple band pass filtering can extract the transmitted clock tone, and low pass filtering can recover the data. Error-free transmissions at 2.488 Gb/s with ˜16 ns clock recovery time were demonstrated.

Optically triggered high voltage switch network and method for switching a high voltage

DOEpatents

El-Sharkawi, Mohamed A.; Andexler, George; Silberkleit, Lee I.

1993-01-19

An optically triggered solid state switch and method for switching a high voltage electrical current. A plurality of solid state switches (350) are connected in series for controlling electrical current flow between a compensation capacitor (112) and ground in a reactive power compensator (50, 50') that monitors the voltage and current flowing through each of three distribution lines (52a, 52b and 52c), which are supplying three-phase power to one or more inductive loads. An optical transmitter (100) controlled by the reactive power compensation system produces light pulses that are conveyed over optical fibers (102) to a switch driver (110') that includes a plurality of series connected optical triger circuits (288). Each of the optical trigger circuits controls a pair of the solid state switches and includes a plurality of series connected resistors (294, 326, 330, and 334) that equalize or balance the potential across the plurality of trigger circuits. The trigger circuits are connected to one of the distribution lines through a trigger capacitor (340). In each switch driver, the light signals activate a phototransistor (300) so that an electrical current flows from one of the energy reservoir capacitors through a pulse transformer (306) in the trigger circuit, producing gate signals that turn on the pair of serially connected solid state switches (350).

Development of advanced seal verification

NASA Technical Reports Server (NTRS)

Workman, Gary L.; Kosten, Susan E.; Abushagur, Mustafa A.

1992-01-01

The purpose of this research is to develop a technique to monitor and insure seal integrity with a sensor that has no active elements to burn-out during a long duration activity, such as a leakage test or especially during a mission in space. The original concept proposed is that by implementing fiber optic sensors, changes in the integrity of a seal can be monitored in real time and at no time should the optical fiber sensor fail. The electrical components which provide optical excitation and detection through the fiber are not part of the seal; hence, if these electrical components fail, they can be easily changed without breaking the seal. The optical connections required for the concept to work does present a functional problem to work out. The utility of the optical fiber sensor for seal monitoring should be general enough that the degradation of a seal can be determined before catastrophic failure occurs and appropriate action taken. Two parallel efforts were performed in determining the feasibility of using optical fiber sensors for seal verification. In one study, research on interferometric measurements of the mechanical response of the optical fiber sensors to seal integrity was studied. In a second study, the implementation of the optical fiber to a typical vacuum chamber was implemented and feasibility studies on microbend experiments in the vacuum chamber were performed. Also, an attempt was made to quantify the amount of pressure actually being applied to the optical fiber using finite element analysis software by Algor.

Understanding the adhesion and optical properties of eutectic metal alloys for solution-processed electronics

NASA Astrophysics Data System (ADS)

Kumar, Prashant; Aggarwal, Shantanu; Narayana, Chandrabhas; Narayan, K. S.

2018-02-01

The role of indium in controlling the adhesion and the optical properties of fusible, low- melting alloys is highlighted in this work. The optical activity of indium-alloy/polymer interface is probed using surface-enhanced Raman spectroscopy, which shows a large increase in polymer Raman modes intensity. Signatures of plasmon and chemically enhanced Raman are visible for more than one polymer. Improvement in adhesion is also reflected in their ability to coat conformally onto the polymer surface resulting in a suitable interface for electrical transport. The electrical characteristics of alloy electrodes, which are printed in ambient conditions, are superior when compared to the thermally evaporated aluminum cathodes. Raman and responsivity measurements indicate that indium (In) forms metal/organic hybrid charge-transfer states at the alloy/polymer interface and assumes a decisive role in controlling the mechanical, optical, and electrical properties of these electrodes. Our studies suggest that the indium present in small quantities (˜5 wt. %) can significantly improve the overall performance of the low-temperature printable eutectic alloy electrodes.

Effect of annealing on structural, optical and electrical properties of SILAR synthesized CuO thin film

NASA Astrophysics Data System (ADS)

Das, M. R.; Mukherjee, A.; Mitra, P.

2017-05-01

Nano crystalline CuO thin films were synthesize on glass substrate using SILAR technique. The structural, optical and electrical properties of the films were carried out for as deposited as well as for films post annealed in the temperature range 300 - 500° C. The X-ray diffraction pattern shows all the films are polycrystalline in nature with monoclinic phase. The crystallite size increase and lattice strain decreases with increase of annealing temperature indicating high quality of the films for annealed films. The value of band gap decreases with increases of annealing temperature of the film. The effect of annealing temperature on ionic conductivity and activation energy to electrical conduction process are discussed.

Phase diagrams of orientational transitions in absorbing nematic liquid crystals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zolot’ko, A. S., E-mail: zolotko@lebedev.ru; Ochkin, V. N.; Smayev, M. P.

2015-05-15

A theory of orientational transitions in nematic liquid crystals (NLCs), which employs the expansion of optical torques acting on the NLC director with respect to the rotation angle, has been developed for NLCs with additives of conformationally active compounds under the action of optical and low-frequency electric and magnetic fields. Phase diagrams of NLCs are constructed as a function of the intensity and polarization of the light field, the strength of low-frequency electric field, and a parameter that characterizes the feedback between the rotation of the NLC director and optical torque. Conditions for the occurrence of first- and second-order transitionsmore » are determined. The proposed theory agrees with available experimental data.« less

Electrically pumped edge-emitting photonic bandgap semiconductor laser

DOEpatents

Lin, Shawn-Yu; Zubrzycki, Walter J.

2004-01-06

A highly efficient, electrically pumped edge-emitting semiconductor laser based on a one- or two-dimensional photonic bandgap (PBG) structure is described. The laser optical cavity is formed using a pair of PBG mirrors operating in the photonic band gap regime. Transverse confinement is achieved by surrounding an active semiconductor layer of high refractive index with lower-index cladding layers. The cladding layers can be electrically insulating in the passive PBG mirror and waveguide regions with a small conducting aperture for efficient channeling of the injection pump current into the active region. The active layer can comprise a quantum well structure. The quantum well structure can be relaxed in the passive regions to provide efficient extraction of laser light from the active region.

Traveling-wave photodetector

DOEpatents

Hietala, V.M.; Vawter, G.A.

1993-12-14

The traveling-wave photodetector of the present invention combines an absorptive optical waveguide and an electrical transmission line, in which optical absorption in the waveguide results in a photocurrent at the electrodes of the electrical transmission line. The optical waveguide and electrical transmission line of the electrically distributed traveling-wave photodetector are designed to achieve matched velocities between the light in the optical waveguide and electrical signal generated on the transmission line. This velocity synchronization provides the traveling-wave photodetector with a large electrical bandwidth and a high quantum efficiency, because of the effective extended volume for optical absorption. The traveling-wave photodetector also provides large power dissipation, because of its large physical size. 4 figures.

Traveling-wave photodetector

DOEpatents

Hietala, Vincent M.; Vawter, Gregory A.

1993-01-01

The traveling-wave photodetector of the present invention combines an absorptive optical waveguide and an electrical transmission line, in which optical absorption in the waveguide results in a photocurrent at the electrodes of the electrical transmission line. The optical waveguide and electrical transmission line of the electrically distributed traveling-wave photodetector are designed to achieve matched velocities between the light in the optical waveguide and electrical signal generated on the transmission line. This velocity synchronization provides the traveling-wave photodetector with a large electrical bandwidth and a high quantum efficiency, because of the effective extended volume for optical absorption. The traveling-wave photodetector also provides large power dissipation, because of its large physical size.

Effect of the electrical currents generated by the intestinal smooth muscle layers on pancreatic enzyme activity: an in vitro study.

PubMed

Dabek, Marta; Podgurniak, Paweł; Piedra, Jose L Valverde; Szymańczyk, Sylwia; Filip, Rafał; Wojtasz-Pajak, Anna; Werpachowska, Eliza; Podgurniak, Malgorzata; Pierzynowski, Stefan G

2007-05-01

Gut enzymes in the small intestine are exposed to extremely low electrical currents (ELEC) generated by the smooth muscle. In the present study, the in vitro tests were undertaken to evaluate the effect of these electric currents on the activity of the proteolytic pancreatic digestive enzymes. A simulator generating the typical electrical activity of pig gut was used for these studies. The electric current emitted by the simulator was transmitted to the samples, containing enzyme and its substrate, using platinum plate electrodes. All samples were incubated at 37 degrees C for 1 h. The changes in optical density, corresponding to enzyme activity, in samples stimulated for 1 h with ELEC was compared with that not exposed to ELEC. The obtained results show that the electrical current with the characteristics of the myoelectrical migrating complex (MMC) has an influence on pancreatic enzyme activity. Increased endopeptidase and reduced exopeptidase activity was noticed in samples treated with ELEC. This observation can be of important as analyzed factors which can alter enzymatic activity of the gut, can thus also affect feed/food digestibility. (c) 2007 Wiley-Liss, Inc.

Methods and apparatus for optical switching using electrically movable optical fibers

DOEpatents

Peterson, Kenneth A [Albuquerque, NM

2007-03-13

Methods and apparatuses for electrically controlled optical switches are presented. An electrically controlled optical switch includes a fixture formed using a laminated dielectric material, a first optical fiber having a fixed segment supported by the fixture and a movable segment extending into a cavity, a second optical fiber having a fixed segment supported by the fixture and an extended segment where an optical interconnect may be established between the first optical fiber and the second optical fiber, and a first electrical actuator functionally coupled to the fixture and the first fiber which alters a position of the moveable segment, based upon a control signal, for changing a state of the optical interconnect between one of two states.

High-temperature optically activated GaAs power switching for aircraft digital electronic control

NASA Technical Reports Server (NTRS)

Berak, J. M.; Grantham, D. H.; Swindal, J. L.; Black, J. F.; Allen, L. B.

1983-01-01

Gallium arsenide high-temperature devices were fabricated and assembled into an optically activated pulse-width-modulated power control for a torque motor typical of the kinds used in jet engine actuators. A bipolar heterojunction phototransistor with gallium aluminum arsenide emitter/window, a gallium arsenide junction field-effect power transistor and a gallium arsenide transient protection diode were designed and fabricated. A high-temperature fiber optic/phototransistor coupling scheme was implemented. The devices assembled into the demonstrator were successfully tested at 250 C, proving the feasibility of actuator-located switching of control power using optical signals transmitted by fibers. Assessments of the efficiency and technical merits were made for extension of this high-temperature technology to local conversion of optical power to electrical power and its control at levels useful for driving actuators. Optical power sources included in the comparisons were an infrared light-emitting diode, an injection laser diode, tungsten-halogen lamps and arc lamps. Optical-to-electrical power conversion was limited to photovoltaics located at the actuator. Impedance matching of the photovoltaic array to the load was considered over the full temperature range, -55 C to 260 C. Loss of photovoltaic efficiency at higher temperatures was taken into account. Serious losses in efficiency are: (1) in the optical source and the cooling which they may require in the assumed 125 C ambient, (2) in the decreased conversion efficiency of the gallium arsenide photovoltaic at 260 C, and (3) in impedance matching. Practical systems require improvements in these areas.

Variations in global thunderstorm activity inferred from the OTD records

NASA Astrophysics Data System (ADS)

Nickolaenko, A. P.; Hayakawa, M.; Sekiguchi, M.

2006-03-01

We use the data on the planetary distribution of thunderstorms collected by optical transient detector (OTD) to derive the properties of global electric activity. Processing of optical data indicates that modern observations from space confirm the general concept of thunderstorm distribution and motion. Close similarity is demonstrated between the World Meteorological Organization data and modern records including Carnegie curve. Departures noted might be caused by thunderstorms redistribution owing to climate change; the issue deserves a special examination.

All-Optical Electrophysiology for Disease Modeling and Pharmacological Characterization of Neurons.

PubMed

Werley, Christopher A; Brookings, Ted; Upadhyay, Hansini; Williams, Luis A; McManus, Owen B; Dempsey, Graham T

2017-09-11

A key challenge for establishing a phenotypic screen for neuronal excitability is measurement of membrane potential changes with high throughput and accuracy. Most approaches for probing excitability rely on low-throughput, invasive methods or lack cell-specific information. These limitations stimulated the development of novel strategies for characterizing the electrical properties of cultured neurons. Among these was the development of optogenetic technologies (Optopatch) that allow for stimulation and recording of membrane voltage signals from cultured neurons with single-cell sensitivity and millisecond temporal resolution. Neuronal activity is elicited using blue light activation of the channelrhodopsin variant 'CheRiff'. Action potentials and synaptic signals are measured with 'QuasAr', a rapid and sensitive voltage-indicating protein with near-infrared fluorescence that scales proportionately with transmembrane potential. This integrated technology of optical stimulation and recording of electrical signals enables investigation of neuronal electrical function with unprecedented scale and precision. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

Selective labeling of retinal ganglion cells with calcium indicators by retrograde loading in vitro

PubMed Central

Behrend, Matthew R.; Ahuja, Ashish K.; Humayun, Mark S.; Weiland, James D.; Chow, Robert H.

2012-01-01

Here we present a retrograde loading technique that makes it possible for the first time to rapidly load a calcium indicator in the majority of retinal ganglion cells (RGCs) in salamander retina, and then to observe physiological activity of these dye-loaded cells. Dextran-conjugated calcium indicator, dissolved in water, was applied to the optic nerve stump. Following dye loading, the isolated retina was mounted on a microelectrode array to demonstrate that electrical activity and calcium activity were preserved, as the retina responded to electrical stimuli. PMID:19428523

Direct electrical-to-optical conversion and light modulation in micro whispering-gallery-mode resonators

NASA Technical Reports Server (NTRS)

Maleki, Lute (Inventor); Levi, Anthony F. J. (Inventor)

2005-01-01

Techniques for directly converting an electrical signal into an optical signal by using a whispering gallery mode optical resonator formed of a dielectric material that allows for direct modulation of optical absorption by the electrical signal.

Electrically tunable Dicke effect in a double-ring resonator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cetin, A. E.; Muestecaplioglu, Oe. E.; Department of Physics, Koc University, Sariyer, Istanbul 34450

We study the finite-element method analysis of the Dicke effect using numerical simulations in an all-optical system of an optical waveguide side-coupled to two interacting ring resonators in a liquid crystal environment. The system is shown to exhibit all the signatures of the Dicke effect under active and reversible control by an applied voltage.

High-fidelity optical reporting of neuronal electrical activity with an ultrafast fluorescent voltage sensor

PubMed Central

St-Pierre, François; Marshall, Jesse D; Yang, Ying; Gong, Yiyang; Schnitzer, Mark J; Lin, Michael Z

2015-01-01

Accurate optical reporting of electrical activity in genetically defined neuronal populations is a long-standing goal in neuroscience. Here we describe Accelerated Sensor of Action Potentials 1 (ASAP1), a novel voltage sensor design in which a circularly permuted green fluorescent protein is inserted within an extracellular loop of a voltage-sensing domain, rendering fluorescence responsive to membrane potential. ASAP1 demonstrates on- and off- kinetics of 2.1 and 2.0 ms, reliably detects single action potentials and subthreshold potential changes, and tracks trains of action potential waveforms up to 200 Hz in single trials. With a favorable combination of brightness, dynamic range, and speed, ASAP1 enables continuous monitoring of membrane potential in neurons at KHz frame rates using standard epifluorescence microscopy. PMID:24755780

A microscale photovoltaic neurostimulator for fiber optic delivery of functional electrical stimulation

NASA Astrophysics Data System (ADS)

Song, Yoon-Kyu; Stein, John; Patterson, William R.; Bull, Christopher W.; Davitt, Kristina M.; Serruya, Mijail D.; Zhang, Jiayi; Nurmikko, Arto V.; Donoghue, John P.

2007-09-01

Recent advances in functional electrical stimulation (FES) show significant promise for restoring voluntary movement in patients with paralysis or other severe motor impairments. Current approaches for implantable FES systems involve multisite stimulation, posing research issues related to their physical size, power and signal delivery, surgical and safety challenges. To explore a different means for delivering the stimulus to a distant muscle nerve site, we have elicited in vitro FES response using a high efficiency microcrystal photovoltaic device as a neurostimulator, integrated with a biocompatible glass optical fiber which forms a lossless, interference-free lightwave conduit for signal and energy transport. As a proof of concept demonstration, a sciatic nerve of a frog is stimulated by the microcrystal device connected to a multimode optical fiber (core diameter of 62.5 µm), which converts optical activation pulses (~100 µs) from an infrared semiconductor laser source (at 852 nm wavelength) into an FES signal.

Lattice strain effects on the optical properties of MoS2 nanosheets

PubMed Central

Yang, Lei; Cui, Xudong; Zhang, Jingyu; Wang, Kan; Shen, Meng; Zeng, Shuangshuang; Dayeh, Shadi A.; Feng, Liang; Xiang, Bin

2014-01-01

“Strain engineering” in functional materials has been widely explored to tailor the physical properties of electronic materials and improve their electrical and/or optical properties. Here, we exploit both in plane and out of plane uniaxial tensile strains in MoS2 to modulate its band gap and engineer its optical properties. We utilize X-ray diffraction and cross-sectional transmission electron microscopy to quantify the strains in the as-synthesized MoS2 nanosheets and apply measured shifts of Raman-active modes to confirm lattice strain modification of both the out-of-plane and in-plane phonon vibrations of the MoS2 nanosheets. The induced band gap evolution due to in-plane and out-of-plane tensile stresses is validated by photoluminescence (PL) measurements, promising a potential route for unprecedented manipulation of the physical, electrical and optical properties of MoS2. PMID:25008782

Plate-slot polymer waveguide modulator on silicon-on-insulator.

PubMed

Qiu, Feng; Spring, Andrew M; Hong, Jianxun; Yokoyama, Shiyoshi

2018-04-30

Electro-optic (EO) modulators are vital for efficient "electrical to optical" transitions and high-speed optical interconnects. In this work, we applied an EO polymer to demonstrate modulators on silicon-on-insulator substrates. The fabricated Mach-Zehnder interferometer (MZI) and ring resonator consist of a Si and TiO 2 slot, in which the EO polymer was embedded to realize a low-driving and large bandwidth modulation. The designed optical and electrical constructions are able to provide a highly concentrated TM mode with low propagation loss and effective EO properties. The fabricated MZI modulator shows a π-voltage-length product of 0.66 V·cm and a 3-dB bandwidth of 31 GHz. The measured EO activity is advantageous to exploit the ring modulator with a resonant tunability of 0.065 nm/V and a 3-dB modulation bandwidth up to 13 GHz.

Scalable fabrication of a hybrid field-effect and acousto-electric device by direct growth of monolayer MoS2/LiNbO3

PubMed Central

Preciado, Edwin; Schülein, Florian J.R.; Nguyen, Ariana E.; Barroso, David; Isarraraz, Miguel; von Son, Gretel; Lu, I-Hsi; Michailow, Wladislaw; Möller, Benjamin; Klee, Velveth; Mann, John; Wixforth, Achim; Bartels, Ludwig; Krenner, Hubert J.

2015-01-01

Lithium niobate is the archetypical ferroelectric material and the substrate of choice for numerous applications including surface acoustic wave radio frequencies devices and integrated optics. It offers a unique combination of substantial piezoelectric and birefringent properties, yet its lack of optical activity and semiconducting transport hamper application in optoelectronics. Here we fabricate and characterize a hybrid MoS2/LiNbO3 acousto-electric device via a scalable route that uses millimetre-scale direct chemical vapour deposition of MoS2 followed by lithographic definition of a field-effect transistor structure on top. The prototypical device exhibits electrical characteristics competitive with MoS2 devices on silicon. Surface acoustic waves excited on the substrate can manipulate and probe the electrical transport in the monolayer device in a contact-free manner. We realize both a sound-driven battery and an acoustic photodetector. Our findings open directions to non-invasive investigation of electrical properties of monolayer films. PMID:26493867

A common-path optical coherence tomography based electrode for structural imaging of nerves and recording of action potentials

NASA Astrophysics Data System (ADS)

Islam, M. Shahidul; Haque, Md. Rezuanul; Oh, Christian M.; Wang, Yan; Park, B. Hyle

2013-03-01

Current technologies for monitoring neural activity either use different variety of electrodes (electrical recording) or require contrast agents introduced exogenously or through genetic modification (optical imaging). Here we demonstrate an optical method for non-contact and contrast agent free detection of nerve activity using phase-resolved optical coherence tomography (pr-OCT). A common-path variation of the pr-OCT is recently implemented and the developed system demonstrated the capability to detect rapid transient structural changes that accompany neural spike propagation. No averaging over multiple trials was required, indicating its capability of single-shot detection of individual impulses from functionally stimulated Limulus optic nerve. The strength of this OCT-based optical electrode is that it is a contactless method and does not require any exogenous contrast agent. With further improvements in accuracy and sensitivity, this optical electrode will play a complementary role to the existing recording technologies in future.

The Optical Harness: a light-weight EMI-immune replacement for legacy electrical wiring harnesses

NASA Astrophysics Data System (ADS)

Stark, Jason B.; Jackson, B. Scott; Trethewey, William

2006-05-01

Electrical wiring harnesses have been used to interconnect control and communication equipment in mobile platforms for over a century. Although they have served this function successfully, they have three problems that are inherent in their design: they are mechanically heavy and stiff, and they are prone to electrical faults, including arcing and Electro-Magnetic Interference (EMI), and they are difficult to maintain when faults occur. These properties are all aspects of the metallic conductors used to build the harnesses. The Optical Harness TM is a photonic replacement for the legacy electrical wiring harness. The Optical Harness TM uses light-weight optical fiber to replace signal wires in an electrical harness. The original electrical connections to the equipment remain, making the Optical Harness TM a direct replacement for the legacy wiring harness. In the backshell of each connector, the electrical signals are converted to optical, and transported on optical fiber, by a deterministic, redundant and fault-tolerant optical network. The Optical Harness TM: * Provides weight savings of 40-50% and unsurpassed flexibility, relative to legacy signal wiring harnesses; * Carries its signals on optical fiber that is free from arcing, EMI, RFI and susceptibility to HPM weapons; * Is self-monitoring during operation, providing non-intrusive predictive and diagnostic capabilities.

High-speed optical phase-shifting apparatus

DOEpatents

Zortman, William A.

2016-11-08

An optical phase shifter includes an optical waveguide, a plurality of partial phase shifting elements arranged sequentially, and control circuitry electrically coupled to the partial phase shifting elements. The control circuitry is adapted to provide an activating signal to each of the N partial phase shifting elements such that the signal is delayed by a clock cycle between adjacent partial phase shifting elements in the sequence. The transit time for a guided optical pulse train between the input edges of consecutive partial phase shifting elements in the sequence is arranged to be equal to a clock cycle, thereby enabling pipelined processing of the optical pulses.

Electrical and optical modeling of poly(3-hexylthiophene):[6,6]-phenyl-C61 butyric acid methyl ester P3HT-PCBM bulk heterojunction solar cells

NASA Astrophysics Data System (ADS)

Brioua, Fathi; Remram, Mohamed; Nechache, Riad; Bourouina, Hicham

2017-11-01

In this work, we investigate a two-dimensional theoretical model for the photon conversion through an integration of the optical and electrical part of multilayer system in a bulk heterojunction solar cell based on poly(3-hexylthiophene) (P3HT)/6,6-phenyl C61-butyric acid methyl ester (PCBM) blend. The optical properties of the studied structure ITO/PEDOT:PSS/P3HT:PCBM/Ca/Al, such as the exciton generation rate and the electrical field distribution, are predicted at vicinity of the active layer and have been used to solve Poisson and continuity, drift-diffusion equations of the electrical model which characterize the electrical behavior of semiconductor device using finite element method (FEM). The electrical parameters such as power conversion efficiency (PCE), open voltage circuit ( V oc), short-circuit current density ( J sc) and fill factor (FF) are extracted from the current-voltage (J-V) characteristics under illumination and in dark conditions. Highest external quantum efficiency (IPCE), up to 60%, is obtained around 520 nm, while a power conversion efficiency (PCE) value of 3.62% is found to be in good agreement with the literature results. Integration of such theoretical approach into technological applications dealing with optoelectrical material performance will rapidly provide to the user accurate data outputs required for efficient validation of proof-of-concepts.

Electrical properties of a liquid crystal dispersed in an electrospun cellulose acetate network

PubMed Central

Danila, Octavian; Ganea, Constantin Paul

2018-01-01

Electro-optical devices that work in a similar fashion as PDLCs (polymer-dispersed liquid crystals), produced from cellulose acetate (CA) electrospun fibers deposited onto indium tin oxide coated glass and a nematic liquid crystal (E7), were studied. CA and the CA/liquid crystal composite were characterized by multiple investigation techniques, such as polarized optical microscopy, dielectric spectroscopy and impedance measurements. Dielectric constant and electric energy loss were studied as a function of frequency and temperature. The activation energy was evaluated and the relaxation time was obtained by fitting the spectra of the dielectric loss with the Havriliak–Negami functions. To determine the electrical characteristics of the studied samples, impedance measurements results were treated using the Cole–Cole diagram and the three-element equivalent model. PMID:29441261

Electrical properties of a liquid crystal dispersed in an electrospun cellulose acetate network.

PubMed

Maximean, Doina Manaila; Danila, Octavian; Almeida, Pedro L; Ganea, Constantin Paul

2018-01-01

Electro-optical devices that work in a similar fashion as PDLCs (polymer-dispersed liquid crystals), produced from cellulose acetate (CA) electrospun fibers deposited onto indium tin oxide coated glass and a nematic liquid crystal (E7), were studied. CA and the CA/liquid crystal composite were characterized by multiple investigation techniques, such as polarized optical microscopy, dielectric spectroscopy and impedance measurements. Dielectric constant and electric energy loss were studied as a function of frequency and temperature. The activation energy was evaluated and the relaxation time was obtained by fitting the spectra of the dielectric loss with the Havriliak-Negami functions. To determine the electrical characteristics of the studied samples, impedance measurements results were treated using the Cole-Cole diagram and the three-element equivalent model.

Thickness dependent structural, optical and electrical properties of Se85In12Bi3 nanochalcogenide thin films

NASA Astrophysics Data System (ADS)

Tripathi, Ravi P.; Zulfequar, M.; Khan, Shamshad A.

2018-04-01

Our aim is to study the thickness dependent effects on structure, electrical and optical properties of Se85In12Bi3 nanochalcogenide thin films. Bulk alloy of Se85In12Bi3 was synthesized by melt-quenching technique. The amorphous as well as glassy nature of Se85In12Bi3 chalcogenide was confirmed by non-isothermal Differential Scanning Calorimetry (DSC) measurements. The nanochalcogenide thin films of thickness 30, 60 and 90 nm were prepared on glass/Si wafer substrate using Physical Vapour Condensation Technique (PVCT). From XRD studies it was found that thin films have amorphous texture. The surface morphology and particle size of films were studied by Field Emission Scanning Electron Microscope (FESEM). From optical studies, different optical parameters were estimated for Se85In12Bi3 thin films at different thickness. It was found that the absorption coefficient (α) and extinction coefficient (k) increases with photon energy and decreases with film thickness. The optical absorption process followed the rule of indirect transitions and optical band gap were found to be increase with film thickness. The value of Urbach energy (Et) and steepness parameter (σ) were also calculated for different film thickness. For electrical studies, dc-conductivity measurement was done at different temperature and activation energy (ΔEc) were determined and found to be increase with film thickness.

Metasurfaces Based on Phase-Change Material as a Reconfigurable Platform for Multifunctional Devices

PubMed Central

Raeis-Hosseini, Niloufar; Rho, Junsuk

2017-01-01

Integration of phase-change materials (PCMs) into electrical/optical circuits has initiated extensive innovation for applications of metamaterials (MMs) including rewritable optical data storage, metasurfaces, and optoelectronic devices. PCMs have been studied deeply due to their reversible phase transition, high endurance, switching speed, and data retention. Germanium-antimony-tellurium (GST) is a PCM that has amorphous and crystalline phases with distinct properties, is bistable and nonvolatile, and undergoes a reliable and reproducible phase transition in response to an optical or electrical stimulus; GST may therefore have applications in tunable photonic devices and optoelectronic circuits. In this progress article, we outline recent studies of GST and discuss its advantages and possible applications in reconfigurable metadevices. We also discuss outlooks for integration of GST in active nanophotonic metadevices. PMID:28878196

Analysis of different tunneling mechanisms of In{sub x}Ga{sub 1−x}As/AlGaAs tunnel junction light-emitting transistors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wu, Cheng-Han; Wu, Chao-Hsin, E-mail: chaohsinwu@ntu.edu.tw; Graduate Institute of Photonics and Optoelectronics, National Taiwan University, No. 1, Sec. 4, Roosevelt Road, Taipei 106, Taiwan

The electrical and optical characteristics of tunnel junction light-emitting transistors (TJLETs) with different indium mole fractions (x = 5% and 2.5%) of the In{sub x}Ga{sub 1−x}As base-collector tunnel junctions have been investigated. Two electron tunneling mechanisms (photon-assisted or direct tunneling) provide additional currents to electrical output and resupply holes back to the base region, resulting in the upward slope of I-V curves and enhanced optical output under forward-active operation. The larger direct tunneling probability and stronger Franz-Keldysh absorption for 5% TJLET lead to higher collector current slope and less optical intensity enhancement when base-collector junction is under reverse-biased.

A Micro-Electrode Array device coupled to a laser-based system for the local stimulation of neurons by optical release of glutamate.

PubMed

Ghezzi, Diego; Menegon, Andrea; Pedrocchi, Alessandra; Valtorta, Flavia; Ferrigno, Giancarlo

2008-10-30

Optical stimulation is a promising approach to investigate the local dynamic responses of cultured neurons. In particular, flash photolysis of caged compounds offers the advantage of allowing the rapid change of concentration of either extracellular or intracellular molecules, such as neurotransmitters or second messengers, for the stimulation or modulation of neuronal activity. We describe here the use of an ultra-violet (UV) laser diode coupled to an optical fibre for the local activation of caged compounds combined with a Micro-Electrode Array (MEA) device. Local uncaging was achieved by UV irradiation through the optical fibre previously positioned by using a red laser diode. The size of the stimulation was determined using caged fluorescein, whereas its efficacy was tested by studying the effect of uncaging the neurotransmitter glutamate. Uncaged glutamate evoked neuronal responses that were recorded using either fluorescence measurements or electrophysiological recordings with MEAs, thus showing the ability of our system to induce local neuronal excitation. This method allows overcoming the limitations of the MEA system related to unfocused electrical stimulation and induction of electrical artefacts. In addition, the coupling of a UV laser diode to an optical fibre allows a precise local stimulation and a quick change of the stimulation point.

A comparative study of optical concentrators for visible light communications

NASA Astrophysics Data System (ADS)

Mulyawan, Rahmat; Gomez, Ariel; Chun, Hyunchae; Rajbhandari, Sujan; Manousiadis, Pavlos P.; Vithanage, Dimali A.; Faulkner, Grahame; Turnbull, Graham A.; Samuel, Ifor D. W.; Collins, Stephen; O'Brien, Dominic

2017-01-01

Given the imminent radio frequency spectrum crunch, Visible Light Communication (VLC) is being proposed as an alternative wireless technology allowing for scalable connectivity to potentially millions of mobile and Internet-of- Things (IoT) devices. A VLC system uses a photo-detector (PD) receiver that converts the optically modulated light from a light source into a modulated electrical signal. The corresponding receiver electrical bandwidth is typically inversely proportional to the PD active area. Consequently, to construct a high-speed VLC link, the PD active area is often substantially reduced and an optical concentrator is used to enhance the receiver collection area. However, to achieve high concentrating factor, the link field-of-view (FOV) needs to be narrow due to the étendue conservation in linear passive optical systems. This paper studies a Fluorescent Concentrator (FC) that breaks this étendue conservation. The FC is not only based on reflective and refractive principles but also makes use of fluorescence process. A comparison between the FC and conventional optical concentrators, namely Compound Parabolic Concentrator (CPC) is also investigated. The trade-off between received signal strength and incoming link angle is demonstrated over 60° coverage. Experimental results show that performance degradation as the link angle increases using FC-based receivers is significantly lower than for conventional CPC.

Optical sensors for electrical elements of a medium voltage distribution network

NASA Astrophysics Data System (ADS)

De Maria, Letizia; Bartalesi, Daniele; Serragli, Paolo; Paladino, Domenico

2012-04-01

The aging of most of the components of the National transmission and distribution system can potentially influence the reliability of power supply in a Medium Voltage (MV) network. In order to prevent possible dangerous situations, selected diagnostic indicators on electrical parts exploiting reliable and potentially low-cost sensors are required. This paper presents results concerning two main research activities regarding the development and application of innovative optical sensors for the diagnostic of MV electrical components. The first concerns a multi-sensor prototype for the detection of pre-discharges in MV switchboards: it is the combination of three different types of sensors operating simultaneously to detect incipient failure and to reduce the occurrence of false alarms. The system is real-time controlled by an embedded computer through a LabView interface. The second activity refers to a diagnostic tool to provide significant real-time information about early aging of MV/Low Voltage (LV) transformers by means of its vibration fingerprint. A miniaturized Optical Micro-Electro-Mechanical System (MEMS) based unit has been assembled for vibration measurements, wireless connected to a remote computer and controlled via LabView interface. Preliminary comparative tests were carried out with standard piezoelectric accelerometers on a conventional MV/LV test transformer under open circuit and in short-circuited configuration.

Frequency-time coherence for all-optical sampling without optical pulse source

PubMed Central

Preußler, Stefan; Raoof Mehrpoor, Gilda; Schneider, Thomas

2016-01-01

Sampling is the first step to convert an analogue optical signal into a digital electrical signal. The latter can be further processed and analysed by well-known electrical signal processing methods. Optical pulse sources like mode-locked lasers are commonly incorporated for all-optical sampling, but have several drawbacks. A novel approach for a simple all-optical sampling is to utilise the frequency-time coherence of each signal. The method is based on only using two coupled modulators driven with an electrical sine wave. Since no optical source is required, a simple integration in appropriate platforms, such as Silicon Photonics might be possible. The presented method grants all-optical sampling with electrically tunable bandwidth, repetition rate and time shift. PMID:27687495

Brain plasticity and functionality explored by nonlinear optical microscopy

NASA Astrophysics Data System (ADS)

Sacconi, L.; Allegra, L.; Buffelli, M.; Cesare, P.; D'Angelo, E.; Gandolfi, D.; Grasselli, G.; Lotti, J.; Mapelli, J.; Strata, P.; Pavone, F. S.

2010-02-01

In combination with fluorescent protein (XFP) expression techniques, two-photon microscopy has become an indispensable tool to image cortical plasticity in living mice. In parallel to its application in imaging, multi-photon absorption has also been used as a tool for the dissection of single neurites with submicrometric precision without causing any visible collateral damage to the surrounding neuronal structures. In this work, multi-photon nanosurgery is applied to dissect single climbing fibers expressing GFP in the cerebellar cortex. The morphological consequences are then characterized with time lapse 3-dimensional two-photon imaging over a period of minutes to days after the procedure. Preliminary investigations show that the laser induced fiber dissection recalls a regenerative process in the fiber itself over a period of days. These results show the possibility of this innovative technique to investigate regenerative processes in adult brain. In parallel with imaging and manipulation technique, non-linear microscopy offers the opportunity to optically record electrical activity in intact neuronal networks. In this work, we combined the advantages of second-harmonic generation (SHG) with a random access (RA) excitation scheme to realize a new microscope (RASH) capable of optically recording fast membrane potential events occurring in a wide-field of view. The RASH microscope, in combination with bulk loading of tissue with FM4-64 dye, was used to simultaneously record electrical activity from clusters of Purkinje cells in acute cerebellar slices. Complex spikes, both synchronous and asynchronous, were optically recorded simultaneously across a given population of neurons. Spontaneous electrical activity was also monitored simultaneously in pairs of neurons, where action potentials were recorded without averaging across trials. These results show the strength of this technique in describing the temporal dynamics of neuronal assemblies, opening promising perspectives in understanding the computations of neuronal networks.

Hybrid intracerebral probe with integrated bare LED chips for optogenetic studies.

PubMed

Ayub, Suleman; Gentet, Luc J; Fiáth, Richárd; Schwaerzle, Michael; Borel, Mélodie; David, François; Barthó, Péter; Ulbert, István; Paul, Oliver; Ruther, Patrick

2017-09-01

This article reports on the development, i.e., the design, fabrication, and validation of an implantable optical neural probes designed for in vivo experiments relying on optogenetics. The probes comprise an array of ten bare light-emitting diode (LED) chips emitting at a wavelength of 460 nm and integrated along a flexible polyimide-based substrate stiffened using a micromachined ladder-like silicon structure. The resulting mechanical stiffness of the slender, 250-μm-wide, 65-μm-thick, and 5- and 8-mm-long probe shank facilitates its implantation into neural tissue. The LEDs are encapsulated by a fluropolymer coating protecting the implant against the physiological conditions in the brain. The electrical interface to the external control unit is provided by 10-μm-thick, highly flexible polyimide cables making the probes suitable for both acute and chronic in vivo experiments. Optical and electrical properties of the probes are reported, as well as their in vivo validation in acute optogenetic studies in transgenic mice. The depth-dependent optical stimulation of both excitatory and inhibitory neurons is demonstrated by altering the brain activity in the cortex and the thalamus. Local network responses elicited by 20-ms-long light pulses of different optical power (20 μW and 1 mW), as well as local modulation of single unit neuronal activity to 1-s-long light pulses with low optical intensity (17 μW) are presented. The ability to modulate neural activity makes these devices suitable for a broad variety of optogenetic experiments.

Comparison of optical and electrical investigations of meat ageing

NASA Astrophysics Data System (ADS)

Prokopyeva, Elena; Tománek, Pavel; Kocová, Lucie; Palai-Dany, Tomáš; Balík, Zdeněk.; Škarvada, Pavel; Grmela, Lubomír.

2013-05-01

Different ultrasonic, electromagnetic, electrical and optical methods are used for meat ageing detection. Muscles are turbid anisotropic media, they exhibit changes in electrical and optical properties according to the direction of the electrical and optical fields in the sample. The work assesses the feasibility of impedance measurements for meat ageing detection and their comparison with optical measurement of scattered light. The pork chop slices were used for their relative homogeneity. An investigation was carried out for the detection of the ageing of unpacked slices exposed directly to the air, and other packed in polyethylene bags. The electrical method is a promising method due to the possibility of getting much information and realizing cheap and fast enough measurement systems. The optical method allows measure the rotation of polarization plane in the range of 95 degrees within considered period. Nevertheless, further work has to be provided to determine closer relationships between optical scattering characteristics, electrical anisotropy in ageing-related tissue structural properties.

Optical and Electrical Characterization of Bulk Grown Indium-Gallium-Arsenide Alloys

DTIC Science & Technology

2010-03-01

OPTICAL AND ELECTRICAL CHARACTERIZATION OF BULK GROWN INDIUM- GALLIUM -ARSENIDE ALLOYS THESIS...Government. AFIT/GAP/ENP/10-M02 OPTICAL AND ELECTRICAL CHARACTERIZATION OF BULK GROWN INDIUM- GALLIUM -ARSENIDE ALLOYS THESIS Presented to...ELECTRICAL CHARACTERIZATION OF BULK GROWN INDIUM- GALLIUM -ARSENIDE ALLOYS Austin C Bergstrom, BS 2 nd Lieutenant, USAF

Monitoring ATP dynamics in electrically active white matter tracts

PubMed Central

Trevisiol, Andrea; Saab, Aiman S; Winkler, Ulrike; Marx, Grit; Imamura, Hiromi; Möbius, Wiebke; Kusch, Kathrin; Nave, Klaus-Armin; Hirrlinger, Johannes

2017-01-01

In several neurodegenerative diseases and myelin disorders, the degeneration profiles of myelinated axons are compatible with underlying energy deficits. However, it is presently impossible to measure selectively axonal ATP levels in the electrically active nervous system. We combined transgenic expression of an ATP-sensor in neurons of mice with confocal FRET imaging and electrophysiological recordings of acutely isolated optic nerves. This allowed us to monitor dynamic changes and activity-dependent axonal ATP homeostasis at the cellular level and in real time. We find that changes in ATP levels correlate well with compound action potentials. However, this correlation is disrupted when metabolism of lactate is inhibited, suggesting that axonal glycolysis products are not sufficient to maintain mitochondrial energy metabolism of electrically active axons. The combined monitoring of cellular ATP and electrical activity is a novel tool to study neuronal and glial energy metabolism in normal physiology and in models of neurodegenerative disorders. DOI: http://dx.doi.org/10.7554/eLife.24241.001 PMID:28414271

Let Them Blow Bubbles.

ERIC Educational Resources Information Center

Korenic, Eileen

1988-01-01

Describes a series of activities and demonstrations involving the science of soap bubbles. Starts with a recipe for bubble solution and gives instructions for several activities on topics such as density, interference colors, optics, static electricity, and galaxy formation. Contains some background information to help explain some of the effects.…

Plasmonic beaming and active control over fluorescent emission.

PubMed

Jun, Young Chul; Huang, Kevin C Y; Brongersma, Mark L

2011-01-01

Nanometallic optical antennas are rapidly gaining popularity in applications that require exquisite control over light concentration and emission processes. The search is on for high-performance antennas that offer facile integration on chips. Here we demonstrate a new, easily fabricated optical antenna design that achieves an unprecedented level of control over fluorescent emission by combining concepts from plasmonics, radiative decay engineering and optical beaming. The antenna consists of a nanoscale plasmonic cavity filled with quantum dots coupled to a miniature grating structure that can be engineered to produce one or more highly collimated beams. Electromagnetic simulations and confocal microscopy were used to visualize the beaming process. The metals defining the plasmonic cavity can be utilized to electrically control the emission intensity and wavelength. These findings facilitate the realization of a new class of active optical antennas for use in new optical sources and a wide range of nanoscale optical spectroscopy applications.

Measurement of optical to electrical and electrical to optical delays with ps-level uncertainty.

PubMed

Peek, H Z; Pinkert, T J; Jansweijer, P P M; Koelemeij, J C J

2018-05-28

We present a new measurement principle to determine the absolute time delay of a waveform from an optical reference plane to an electrical reference plane and vice versa. We demonstrate a method based on this principle with 2 ps uncertainty. This method can be used to perform accurate time delay determinations of optical transceivers used in fiber-optic time-dissemination equipment. As a result the time scales in optical and electrical domain can be related to each other with the same uncertainty. We expect this method will be a new breakthrough in high-accuracy time transfer and absolute calibration of time-transfer equipment.

Lateral geniculate body evoked potentials elicited by visual and electrical stimulation.

PubMed

Choi, Chang Wook; Kim, Pan Sang; Shin, Sun Ae; Yang, Ji Yeon; Yang, Yun Sik

2014-08-01

Blind individuals who have photoreceptor loss are known to perceive phosphenes with electrical stimulation of their remaining retinal ganglion cells. We proposed that implantable lateral geniculate body (LGB) stimulus electrode arrays could be used to generate phosphene vision. We attempted to refine the basic reference of the electrical evoked potentials (EEPs) elicited by microelectrical stimulations of the optic nerve, optic tract and LGB of a domestic pig, and then compared it to visual evoked potentials (VEPs) elicited by short-flash stimuli. For visual function measurement, VEPs in response to short-flash stimuli on the left eye of the domestic pig were assessed over the visual cortex at position Oz with the reference electrode at Fz. After anesthesia, linearly configured platinum wire electrodes were inserted into the optic nerve, optic track and LGB. To determine the optimal stimulus current, EEPs were recorded repeatedly with controlling the pulse and power. The threshold of current and charge density to elicit EEPs at 0.3 ms pulse duration was about ±10 µA. Our experimental results showed that visual cortex activity can be effectively evoked by stimulation of the optic nerve, optic tract and LGB using penetrating electrodes. The latency of P1 was more shortened as the electrical stimulation was closer to LGB. The EEPs of two-channel in the visual cortex demonstrated a similar pattern with stimulation of different spots of the stimulating electrodes. We found that the LGB-stimulated EEP pattern was very similar to the simultaneously generated VEP on the control side, although implicit time deferred. EEPs and VEPs derived from visual-system stimulation were compared. The LGB-stimulated EEP wave demonstrated a similar pattern to the VEP waveform except implicit time, indicating prosthetic-based electrical stimulation of the LGB could be utilized for the blind to perceive vision of phosphenes.

Hybrid plasmonic electro-optical absorption modulator based on epsilon-near-zero characteristics of ITO

NASA Astrophysics Data System (ADS)

Abdelatty, M. Y.; Badr, M. M.; Swillam, M. A.

2018-03-01

Using transparent conducting oxides (TCOs), like indium-tin-oxide (ITO), for optical modulation attracted research interest because of their epsilon-near-zero (ENZ) characteristics at telecom wavelengths. Utilizing indium-tin-oxide (ITO) in multilayer structure modulators, optical absorption of the active ITO layer can be electrically modulated over a large spectrum range. Although they show advances over common silicon electro-optical modulators (EOMs), they suffer from high insertion losses. To reduce insertion losses and device footprints without sacrificing bandwidth and modulation strength, slot waveguides are promising options because of their high optical confinement. In this paper, we present the study and the design of an electro-optical absorption modulator based on electrically tuning ITO carrier density inside a MOS structure. The device structure is based on dielectric slot waveguide with an ITO plasmonic waveguide modulation section. By changing the dimensions, the effective refractive indices for the slot mode and the off-sate mode of the plasmonic section can be matched. When applying electric field to the plasmonic section (on-state), carriers are generated at the ITO-dielectric interface that result in changing the layer where the electric field is confined from a transparent layer into a lossy layer. A finite difference time domain method with perfect matching layer (PML) absorbing boundary conditions is taken up to simulate and analyze this design. An extinction ratio of 2.3 dB is achieved for a 1-μm-short modulation section, at the telecommunications wavelength (1.55 μm). This EOM has advantages of simple design, easy fabrication, compact size, compatibility with existing silicon photonics platforms, as well as broadband performance.

Electro-Optic Modulator and Method

DTIC Science & Technology

An optical intensity modulator which uses a Sagnac interferometer having an electro - optic phase modulator therein. An electric modulation signal is...modulating the optical signals by the electrical signal, the electro - optic effect in the modulator phase shifts the optical signals with respect to one another

A strong electro-optically active lead-free ferroelectric integrated on silicon

NASA Astrophysics Data System (ADS)

Abel, Stefan; Stöferle, Thilo; Marchiori, Chiara; Rossel, Christophe; Rossell, Marta D.; Erni, Rolf; Caimi, Daniele; Sousa, Marilyne; Chelnokov, Alexei; Offrein, Bert J.; Fompeyrine, Jean

2013-04-01

The development of silicon photonics could greatly benefit from the linear electro-optical properties, absent in bulk silicon, of ferroelectric oxides, as a novel way to seamlessly connect the electrical and optical domain. Of all oxides, barium titanate exhibits one of the largest linear electro-optical coefficients, which has however not yet been explored for thin films on silicon. Here we report on the electro-optical properties of thin barium titanate films epitaxially grown on silicon substrates. We extract a large effective Pockels coefficient of reff=148 pm V-1, which is five times larger than in the current standard material for electro-optical devices, lithium niobate. We also reveal the tensor nature of the electro-optical properties, as necessary for properly designing future devices, and furthermore unambiguously demonstrate the presence of ferroelectricity. The integration of electro-optical active films on silicon could pave the way towards power-efficient, ultra-compact integrated devices, such as modulators, tuning elements and bistable switches.

"METHOD": A tool for mechanical, electrical, thermal, and optical characterization of single lens module design

NASA Astrophysics Data System (ADS)

Besson, Pierre; Dominguez, Cesar; Voarino, Philippe; Garcia-Linares, Pablo; Weick, Clement; Lemiti, Mustapha; Baudrit, Mathieu

2015-09-01

The optical characterization and electrical performance evaluation are essential in the design and optimization of a concentrator photovoltaic system. The geometry, materials, and size of concentrator optics are diverse and different environmental conditions impact their performance. CEA has developed a new concentrator photovoltaic system characterization bench, METHOD, which enables multi-physics optimization studies. The lens and cell temperatures are controlled independently with the METHOD to study their isolated effects on the electrical and optical performance of the system. These influences can be studied in terms of their effect on optical efficiency, focal distance, spectral sensitivity, electrical efficiency, or cell current matching. Furthermore, the irradiance map of a concentrator optic can be mapped to study its variations versus the focal length or the lens temperature. The present work shows this application to analyze the performance of a Fresnel lens linking temperature to optical and electrical performance.

Electrical and optical percolations in PMMA/GNP composite films

NASA Astrophysics Data System (ADS)

Arda, Ertan; Mergen, Ömer Bahadır; Pekcan, Önder

2018-05-01

Effects of graphene nanoplatelet (GNP) addition on the electrical conductivity and optical absorbance of poly(methyl methacrylate)/graphene nanoplatelet (PMMA/GNP) composite films were studied. Optical absorbance and two point probe resistivity techniques were used to determine the variations of the optical and electrical properties of the composites, respectively. Absorbance intensity, A, and surface resistivity, Rs, of the composite films were monitored as a function of GNP mass fraction (M) at room temperature. Absorbance intensity values of the composites were increased and surface resistivity values were decreased by increasing the content of GNP in the composite. Electrical and optical percolation thresholds of composite films were determined as Mσ = 27.5 wt.% and Mop = 26.6 wt.%, respectively. The conductivity and the optical results were attributed to the classical and site percolation theories, respectively. Optical (βop) and electrical (βσ) critical exponents were calculated as 0.40 and 1.71, respectively.

Meta-structure and tunable optical device including the same

DOEpatents

Han, Seunghoon; Papadakis, Georgia Theano; Atwater, Harry

2017-12-26

A meta-structure and a tunable optical device including the same are provided. The meta-structure includes a plurality of metal layers spaced apart from one another, an active layer spaced apart from the plurality of metal layers and having a carrier concentration that is tuned according to an electric signal applied to the active layer and the plurality of metal layers, and a plurality of dielectric layers spaced apart from one another and each having one surface contacting a metal layer among the plurality of metal layers and another surface contacting the active layer.

Electrical and Optical Activation of Mesoscale Neural Circuits with Implications for Coding.

PubMed

Millard, Daniel C; Whitmire, Clarissa J; Gollnick, Clare A; Rozell, Christopher J; Stanley, Garrett B

2015-11-25

Artificial activation of neural circuitry through electrical microstimulation and optogenetic techniques is important for both scientific discovery of circuit function and for engineered approaches to alleviate various disorders of the nervous system. However, evidence suggests that neural activity generated by artificial stimuli differs dramatically from normal circuit function, in terms of both the local neuronal population activity at the site of activation and the propagation to downstream brain structures. The precise nature of these differences and the implications for information processing remain unknown. Here, we used voltage-sensitive dye imaging of primary somatosensory cortex in the anesthetized rat in response to deflections of the facial vibrissae and electrical or optogenetic stimulation of thalamic neurons that project directly to the somatosensory cortex. Although the different inputs produced responses that were similar in terms of the average cortical activation, the variability of the cortical response was strikingly different for artificial versus sensory inputs. Furthermore, electrical microstimulation resulted in highly unnatural spatial activation of cortex, whereas optical input resulted in spatial cortical activation that was similar to that induced by sensory inputs. A thalamocortical network model suggested that observed differences could be explained by differences in the way in which artificial and natural inputs modulate the magnitude and synchrony of population activity. Finally, the variability structure in the response for each case strongly influenced the optimal inputs for driving the pathway from the perspective of an ideal observer of cortical activation when considered in the context of information transmission. Artificial activation of neural circuitry through electrical microstimulation and optogenetic techniques is important for both scientific discovery and clinical translation. However, neural activity generated by these artificial means differs dramatically from normal circuit function, both locally and in the propagation to downstream brain structures. The precise nature of these differences and the implications for information processing remain unknown. The significance of this work is in quantifying the differences, elucidating likely mechanisms underlying the differences, and determining the implications for information processing. Copyright © 2015 the authors 0270-6474/15/3515702-14$15.00/0.

Teacher's Guide for Optics. Elementary Science Study.

ERIC Educational Resources Information Center

Lange, Robert V.; And Others

This teacher's guide suggests activities that provide opportunities for upper elementary students to explore, by direct experiment, many of the properties of light. Equipment is listed and construction of a light source is detailed. Instructions are given for setting up a classroom with electrical equipment. Activities are described in units…

Fiber optic accelerometer

NASA Technical Reports Server (NTRS)

August, R. R.

1981-01-01

Low-cost, rugged lightweight accelerometer has been developed that converts mechanical motion into digitized optical outputs and is immune to electromagnetic and electrostatic interferences. Instrument can be placed in hostile environment, such as engine under test, and output led out through miscellany of electrical fields, high temperatures, etc., by optic fiber cables to benign environment of test panel. There, digitized optical signals can be converted to electrical signals for use in standard electrical equipment or used directly in optical devices, such as optical digital computer.

Optical and electrical properties of bismuth-sulfide (Bi2S3) thin films prepared by thermal evaporation.

NASA Astrophysics Data System (ADS)

Mahmoud, Siham; Sharaf, Fouad

Thin films of Bi2S3, of thickness in the range 300 to 500 nm, were produced by thermal evaporation technique. The reaction consisted in depositing the two elements (bismuth and sulfur) from a boat source and allowing their atoms to interdiffuse to form the compound during the deposition on quartz substrates. The material has been characterized by X-ray studies, optical and electrical measurements. When these films were annealed at 353 K, 393 K and 453 K for 5 hours, a nearly amorphous to polycrystalline transition was observed. The absorption coefficient revealed the existence of an allowed direct transition with Eg = 1.56 eV. The activation energies for electrical conduction in low and high temperature regions are 0.28 eV and 0.73 eV, respectively.

Integrated Nanoscale Antenna-LED for On-Chip Optical Communication

NASA Astrophysics Data System (ADS)

Fortuna, Seth

Traditional semiconductor light emitting diodes (LEDs) have low modulation speed because of long spontaneous emission lifetime. Spontaneous emission in semiconductors (and indeed most light emitters) is an inherently slow process owing to the size mismatch between the dipole length of the optical dipole oscillators responsible for light emission and the wavelength of the emitted light. More simply stated: semiconductors behave as a poor antenna for its own light emission. By coupling a semiconductor at the nanoscale to an external antenna, the spontaneous emission rate can be dramatically increased alluding to the exciting possibility of an antenna-LED that can be directly modulated faster than the laser. Such an antenna-LED is well-suited as a light source for on-chip optical communication where small size, fast speed, and high efficiency are needed to achieve the promised benefit of reduced power consumption of on-chip optical interconnect links compared with less efficient electrical interconnect links. Despite the promise of the antenna-LED, significant challenges remain to implement an antenna-coupled device in a monolithically integrated manner. Notably, most demonstrations of antenna-enhanced spontaneous emission have relied upon optical pumping of the light emitting material which is useful for fundamental studies; however, an electrical injection scheme is required for practical implementation of an antenna-LED. In this dissertation, demonstration of an electrically-injected III-V antenna-LED is reported: an important milestone toward on-chip optical interconnects. In the first part of this dissertation, the general design principles of enhancing the spontaneous emission rate of a semiconductor with an optical antenna is discussed. The cavity-backed slot antenna is shown to be uniquely suited for an electrically-injected antenna-LED because of large spontaneous emission enhancement, simple fabrication, and directional emission of light. The design, fabrication, and experimental results of the electrically-injected III-V antenna-LED is then presented. Clear evidence of antenna-enhanced electroluminescence is demonstrated including a large increase in the emitted light intensity with respect to an LED without antenna. Furthermore, it is shown that the active region emission wavelength is influenced by the antenna resonance and the emitted light is polarized; consistent with the expected behavior of the cavity-backed slot antenna. An antenna-LED consisting of a InGaAs quantum well active region is shown to have a large 200-fold enhancement of the spontaneous emission rate. In the last half of this dissertation, the performance of the antenna-LED is discussed. Remarkably, despite the high III-V surface recombination velocity, it is shown that an efficient antenna-LED consisting of an InGaAs active region is possible with an antenna-enhanced spontaneous emission rate. This is true provided the active region surface quality is preserved through the entire device process. A novel technique to preserve and clean InGaAs surfaces is reported. Finally, a rate-equation analysis shows that the optimized antenna-LED with cavity-backed slot antenna is fundamentally capable of achieving greater than 100 GHz direct modulation rate at high efficiency thus showing that an antenna-LED faster than the laser is achievable with this device architecture.

Electric field induced optical gain of a hydrogenic impurity in a Cd{sub 0.8}Zn{sub 0.2}Se/ZnSe parabolic quantum dot

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jasmine, P. Christina Lily; Peter, A. John, E-mail: a.john.peter@gmail.com

The dependence of electric field on the electronic and optical properties is investigated in a Cd{sub 0.8}Zn{sub 0.2}Se/ZnSe quantum dot. The hydrogenic binding energy, in the presence of electric field, is calculated with the spatial confinement effect. The electric field dependent optical gain with the photon energy is found using compact density matrix method. The results show that the electric field has a great influence on the optical properties of II-VI semiconductor quantum dot.

Memory device using movement of protons

DOEpatents

Warren, W.L.; Vanheusden, K.J.R.; Fleetwood, D.M.; Devine, R.A.B.

1998-11-03

An electrically written memory element is disclosed utilizing the motion of protons within a dielectric layer surrounded by layers on either side to confine the protons within the dielectric layer with electrode means attached to the surrounding layers to change the spatial position of the protons within the dielectric layer. The device is preferably constructed as a silicon-silicon dioxide-silicon layered structure with the protons being introduced to the structure laterally through the exposed edges of the silicon dioxide layer during a high temperature anneal in an atmosphere containing hydrogen gas. The device operates at low power, is preferably nonvolatile, is radiation tolerant, and is compatible with convention silicon MOS processing for integration with other microelectronic elements on the same silicon substrate. With the addition of an optically active layer, the memory element becomes an electrically written, optically read optical memory element. 19 figs.

Memory device using movement of protons

DOEpatents

Warren, William L.; Vanheusden, Karel J. R.; Fleetwood, Daniel M.; Devine, Roderick A. B.

1998-01-01

An electrically written memory element utilizing the motion of protons within a dielectric layer surrounded by layers on either side to confine the protons within the dielectric layer with electrode means attached to the surrounding layers to change the spatial position of the protons within the dielectric layer. The device is preferably constructed as a silicon-silicon dioxide-silicon layered structure with the protons being introduced to the structure laterally through the exposed edges of the silicon dioxide layer during a high temperature anneal in an atmosphere containing hydrogen gas. The device operates at low power, is preferably nonvolatile, is radiation tolerant, and is compatible with convention silicon MOS processing for integration with other microelectronic elements on the same silicon substrate. With the addition of an optically active layer, the memory element becomes an electrically written, optically read optical memory element.

Memory device using movement of protons

DOEpatents

Warren, William L.; Vanheusden, Karel J. R.; Fleetwood, Daniel M.; Devine, Roderick A. B.

2000-01-01

An electrically written memory element utilizing the motion of protons within a dielectric layer surrounded by layers on either side to confine the protons within the dielectric layer with electrode means attached to the surrounding layers to change the spatial position of the protons within the dielectric layer. The device is preferably constructed as a silicon-silicon dioxide-silicon layered structure with the protons being introduced to the structure laterally through the exposed edges of the silicon dioxide layer during a high temperature anneal in an atmosphere containing hydrogen gas. The device operates at low power, is preferably nonvolatile, is radiation tolerant, and is compatible with convention silicon MOS processing for integration with other microelectronic elements on the same silicon substrate. With the addition of an optically active layer, the memory element becomes an electrically written, optically read optical memory element.

Electric dipole spin resonance in a quantum spin dimer system driven by magnetoelectric coupling

NASA Astrophysics Data System (ADS)

Kimura, Shojiro; Matsumoto, Masashige; Akaki, Mitsuru; Hagiwara, Masayuki; Kindo, Koichi; Tanaka, Hidekazu

2018-04-01

In this Rapid Communication, we propose a mechanism for electric dipole active spin resonance caused by spin-dependent electric polarization in a quantum spin gapped system. This proposal was successfully confirmed by high-frequency electron spin resonance (ESR) measurements of the quantum spin dimer system KCuCl3. ESR measurements by an illuminating linearly polarized electromagnetic wave reveal that the optical transition between the singlet and triplet states in KCuCl3 is driven by an ac electric field. The selection rule of the observed transition agrees with the calculation by taking into account spin-dependent electric polarization. We suggest that spin-dependent electric polarization is effective in achieving fast control of quantum spins by an ac electric field.

A Surface-Coupled Optical Trap with 1-bp Precision via Active Stabilization

PubMed Central

Okoniewski, Stephen R.; Carter, Ashley R.; Perkins, Thomas T.

2017-01-01

Optical traps can measure bead motions with Å-scale precision. However, using this level of precision to infer 1-bp motion of molecular motors along DNA is difficult, since a variety of noise sources degrade instrumental stability. In this chapter, we detail how to improve instrumental stability by (i) minimizing laser pointing, mode, polarization, and intensity noise using an acousto-optical-modulator mediated feedback loop and (ii) minimizing sample motion relative to the optical trap using a 3-axis piezo-electric-stage mediated feedback loop. These active techniques play a critical role in achieving a surface stability of 1 Å in 3D over tens of seconds and a 1-bp stability and precision in a surface-coupled optical trap over a broad bandwidth (Δf = 0.03–2 Hz) at low force (6 pN). These active stabilization techniques can also aid other biophysical assays that would benefit from improved laser stability and/or Å-scale sample stability, such as atomic force microscopy and super-resolution imaging. PMID:27844426

Optical gain in colloidal quantum dots achieved with direct-current electrical pumping

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lim, Jaehoon; Park, Young-Shin; Klimov, Victor Ivanovich

Chemically synthesized semiconductor quantum dots (QDs) can potentially enable solution-processable laser diodes with a wide range of operational wavelengths, yet demonstrations of lasing from the QDs are still at the laboratory stage. An important challenge—realization of lasing with electrical injection—remains unresolved, largely due to fast nonradiative Auger recombination of multicarrier states that represent gain-active species in the QDs. Here in this paper, we present population inversion and optical gain in colloidal nanocrystals realized with direct-current electrical pumping. Using continuously graded QDs, we achieve a considerable suppression of Auger decay such that it can be outpaced by electrical injection. Further, wemore » apply a special current-focusing device architecture, which allows us to produce high current densities (j) up to ~18 A cm -2 without damaging either the QDs or the injection layers. The quantitative analysis of electroluminescence and current-modulated transmission spectra indicates that with j = 3-4 A cm -2 we achieve the population inversion of the band-edge states.« less

Optical gain in colloidal quantum dots achieved with direct-current electrical pumping

NASA Astrophysics Data System (ADS)

Lim, Jaehoon; Park, Young-Shin; Klimov, Victor I.

2018-01-01

Chemically synthesized semiconductor quantum dots (QDs) can potentially enable solution-processable laser diodes with a wide range of operational wavelengths, yet demonstrations of lasing from the QDs are still at the laboratory stage. An important challenge--realization of lasing with electrical injection--remains unresolved, largely due to fast nonradiative Auger recombination of multicarrier states that represent gain-active species in the QDs. Here we present population inversion and optical gain in colloidal nanocrystals realized with direct-current electrical pumping. Using continuously graded QDs, we achieve a considerable suppression of Auger decay such that it can be outpaced by electrical injection. Further, we apply a special current-focusing device architecture, which allows us to produce high current densities (j) up to ~18 A cm-2 without damaging either the QDs or the injection layers. The quantitative analysis of electroluminescence and current-modulated transmission spectra indicates that with j = 3-4 A cm-2 we achieve the population inversion of the band-edge states.

Optical gain in colloidal quantum dots achieved with direct-current electrical pumping

DOE PAGES

Lim, Jaehoon; Park, Young-Shin; Klimov, Victor Ivanovich

2017-11-20

Chemically synthesized semiconductor quantum dots (QDs) can potentially enable solution-processable laser diodes with a wide range of operational wavelengths, yet demonstrations of lasing from the QDs are still at the laboratory stage. An important challenge—realization of lasing with electrical injection—remains unresolved, largely due to fast nonradiative Auger recombination of multicarrier states that represent gain-active species in the QDs. Here in this paper, we present population inversion and optical gain in colloidal nanocrystals realized with direct-current electrical pumping. Using continuously graded QDs, we achieve a considerable suppression of Auger decay such that it can be outpaced by electrical injection. Further, wemore » apply a special current-focusing device architecture, which allows us to produce high current densities (j) up to ~18 A cm -2 without damaging either the QDs or the injection layers. The quantitative analysis of electroluminescence and current-modulated transmission spectra indicates that with j = 3-4 A cm -2 we achieve the population inversion of the band-edge states.« less

Structural, optical and ac electrical characterization of CBD synthesized NiO thin films: Influence of thickness

NASA Astrophysics Data System (ADS)

Das, M. R.; Mukherjee, A.; Mitra, P.

2017-09-01

We have studied the electrical conductivity, dielectric relaxation mechanism and impedance spectroscopy characteristics of nickel oxide (NiO) thin films synthesized by chemical bath deposition (CBD) method. Thickness dependent structural, optical and ac electrical characterization has been carried out and deposition time was varied to control the thickness. The material has been characterized using X-ray diffraction and UV-VIS spectrophotometer. Impedance spectroscopy analysis confirmed enhancement of ac conductivity and dielectric constant for films deposited with higher deposition time. Decrease of grain size in thicker films were confirmed from XRD analysis and activation energy of the material for electrical charge hopping process was increased with thickness of the film. Decrease in band gap in thicker films were observed which could be associated with creation of additional energy levels in the band gap of the material. Cole-Cole plot shows contribution of both grain and grain boundary towards total resistance and capacitance. The overall resistance was found to decrease from 14.6 × 105 Ω for 30 min deposited film ( 120 nm thick) to 2.42 × 105 Ω for 120 min deposited film ( 307 nm thick). Activation energy value to electrical conduction process evaluated from conductivity data was found to decrease with thickness. Identical result was obtained from relaxation time approach suggesting hopping mechanism of charge carriers.

Electromagnon excitation in the field-induced nonlinear ferrimagnetic phase of Ba 2Mg 2Fe 12O 22 studied by polarized inelastic neutron and terahertz time-domain optical spectroscopy

DOE PAGES

Nakajima, Taro; Takahashi, Youtarou; Kibayashi, Shunsuke; ...

2016-01-19

We have studied magnetic excitations in a field-induced noncollinear commensurate ferrimagnetic phase of Ba 2Mg 2Fe 12O 22 by means of polarized inelastic neutron scattering (PINS) and terahertz (THz) time-domain optical spectroscopy under magnetic field. A previous THz spectroscopy study reported that the field-induced phase exhibits electric-dipole-active excitations with energies of around 5 meV [Kida et al., Phys. Rev. B 83, 064422 (2011)]. In the present PINS measurements, we observed inelastic scattering signals around 5 meV at the zone center in the spin-flip channel. This directly shows that the electric-dipole-active excitations are indeed of magnetic origin, that is, electromagnons. Inmore » addition, the present THz spectroscopy confirms that the excitations have oscillating electric polarization parallel to the c axis. In terms of the spin-current model (Katsura-Nagaosa-Balatsky model), the noncollinear magnetic order in the field-induced phase can induce static electric polarization perpendicular to the c axis, but not dynamic electric polarization along the c axis. Furthermore, we suggest that the electromagnon excitations can be explained by applying the magnetostriction model to the out-of-phase oscillations of the magnetic moments, which is deduced from the present experimental results.« less

Innovative on board payload optical architecture for high throughput satellites

NASA Astrophysics Data System (ADS)

Baudet, D.; Braux, B.; Prieur, O.; Hughes, R.; Wilkinson, M.; Latunde-Dada, K.; Jahns, J.; Lohmann, U.; Fey, D.; Karafolas, N.

2017-11-01

For the next generation of HighThroughPut (HTP) Telecommunications Satellites, space end users' needs will result in higher link speeds and an increase in the number of channels; up to 512 channels running at 10Gbits/s. By keeping electrical interconnections based on copper, the constraints in term of power dissipation, number of electrical wires and signal integrity will become too demanding. The replacement of the electrical links by optical links is the most adapted solution as it provides high speed links with low power consumption and no EMC/EMI. But replacing all electrical links by optical links of an On Board Payload (OBP) is challenging. It is not simply a matter of replacing electrical components with optical but rather the whole concept and architecture have to be rethought to achieve a high reliability and high performance optical solution. In this context, this paper will present the concept of an Innovative OBP Optical Architecture. The optical architecture was defined to meet the critical requirements of the application: signal speed, number of channels, space reliability, power dissipation, optical signals crossing and components availability. The resulting architecture is challenging and the need for new developments is highlighted. But this innovative optically interconnected architecture will substantially outperform standard electrical ones.

Electrochemical and physical properties of electroplated CuO thin films.

PubMed

Dhanasekaran, V; Mahalingam, T

2013-01-01

Cupric oxide thin films have been prepared on ITO glass substrates from an aqueous electrolytic bath containing CuSO4 and tartaric acid. Growth mechanism has been analyzed using cyclic voltammetry. The role of pH on the structural, morphological, compositional, electrical and optical properties of CuO films is investigated. The structural studies revealed that the deposited films are polycrystalline in nature with a cubic structure. The preferential orientation of CuO thin films is found to be along (111) plane. X-ray line profile analysis has been carried out to determine the microstructural parameters of CuO thin films. The pyramid shaped grains are observed from SEM and AFM images. The optical band gap energy and electrical activation energy is found to be 1.45 and 0.37 eV, respectively. Also, the optical constants of CuO thin films such as refractive index (n), complex dielectric constant (epsilon) extinction coefficient (k) and optical conductivity (sigma) are evaluated.

Demonstration of glass-based photonic interposer for mid-board-optical engines and electrical-optical circuit board (EOCB) integration strategy

NASA Astrophysics Data System (ADS)

Schröder, H.; Neitz, M.; Schneider-Ramelow, M.

2018-02-01

Due to its optical transparency and superior dielectric properties glass is regarded as a promising candidate for advanced applications as active photonic interposer for mid-board-optics and optical PCB waveguide integration. The concepts for multi-mode and single-mode photonic system integration are discussed and related demonstration project results will be presented. A hybrid integrated photonic glass body interposer with integrated optical lenses for multi-mode data communication wavelength of 850 nm have been realized. The paper summarizes process developments which allow cost efficient metallization of TGV. Electro-optical elements like photodiodes and VCSELs can be directly flip-chip mounted on the glass substrate according to the desired lens positions. Furthermore results for a silicon photonic based single-mode active interposer integration onto a single mode glass made EOCB will be compared in terms of packaging challenges. The board level integration strategy for both of these technological approaches and general next generation board level integration concepts for photonic interposer will be introductorily discussed.

Optical, electrical, thermal properties of cadmium chloride doped PVA – PVP blend

DOE Office of Scientific and Technical Information (OSTI.GOV)

Baraker, Basavarajeshwari M.; Hammannavar, Preeti B.; Lobo, Blaise, E-mail: blaise.lobo@gmail.com

2015-06-24

Films of polyvinylalcohol (PVA) – polyvinylpyrrolidone (PVP) blend doped with Cadmium Chloride (CdCl{sub 2}) in the doping range 1 wt% to 40 wt% were prepared by solution casting technique. These films were characterized using optical/UV-Vis- NIR spectroscopy, Differential Scanning Calorimetry (DSC) and DC electrical measurements. The UV-Visible spectra were quantitatively analyzed to yield the optical parameters. The UV-Visible Spectra show intermediate absorption bands (before the final absorption edge) due to formation of energy bands in the forbidden gap of PVA-PVP. There is a prominent absorption band at 2.9 eV, from 0.5 wt% up to 1.8 wt% doping level (DL) causedmore » by the dopant (CdCl{sub 2}). The DC electrical studies showed an increase in activation energy from 2.8 eV at 0.5 wt% DL up to 3.5 eV at 4.4 wt% DL, reaching a low of 2.4 eV at 11.2 wt% DL. DSC scans show evidence of formation of chain fragments, at doping levels beyond 8 wt%.« less

Nighttime observations of thunderstorm electrical activity from a high altitude airplane

NASA Technical Reports Server (NTRS)

Brook, M.; Rhodes, C.; Vaughan, O. H., Jr.; Orville, R. E.; Vonnegut, B.

1984-01-01

Photographs from a NASA U-2 airplane flying over nocturnal thunderstorms show frequent lightning activity in the upper part of the cloud. In some cases, unobscured segments of lightning channels 1 km or longer are visible in clear air around and above the cloud. Multiple images of lightning channels indicate multiple discharges in the same channel. Photographs taken through a diffraction grating show that the lightning has a spectrum similar to that observed in the lower troposphere. Lightning spectra obtained with a slitless line-scan spectrometer show strong singly ionized nitrogen emissions at 463.0 and 500.5 nm. Field changes measured with an electric field-change meter correlate with pulses measured with a photocell optical system. Optical signals corresponding to dart leader, return stroke, and continuing current events are readily distinguished in the scattered light emerging from the cloud surface. The variation of light intensity with time in lightning events is consistent with predicted modification of optical lightning signals by clouds. It appears that satellite based optical sensor measurements cannot provide reliable information on current rise times in return strokes. On the other hand, discrimination between cloud-to-ground and intracloud flashes and the counting of ground strokes is possible using the optical pulse pairs which have been identified with leader, return-stroke events in the cloud-to-ground flashes studied.

Optical changes in cortical tissue during seizure activity using optical coherence tomography (Conference Presentation)

NASA Astrophysics Data System (ADS)

Ornelas, Danielle; Hasan, Md.; Gonzalez, Oscar; Krishnan, Giri; Szu, Jenny I.; Myers, Timothy; Hirota, Koji; Bazhenov, Maxim; Binder, Devin K.; Park, Boris H.

2017-02-01

Epilepsy is a chronic neurological disorder characterized by recurrent and unpredictable seizures. Electrophysiology has remained the gold standard of neural activity detection but its resolution and high susceptibility to noise and motion artifact limit its efficiency. Optical imaging techniques, including fMRI, intrinsic optical imaging, and diffuse optical imaging, have also been used to detect neural activity yet these techniques rely on the indirect measurement of changes in blood flow. A more direct optical imaging technique is optical coherence tomography (OCT), a label-free, high resolution, and minimally invasive imaging technique that can produce depth-resolved cross-sectional and 3D images. In this study, OCT was used to detect non-vascular depth-dependent optical changes in cortical tissue during 4-aminopyridine (4-AP) induced seizure onset. Calculations of localized optical attenuation coefficient (µ) allow for the assessment of depth-resolved volumetric optical changes in seizure induced cortical tissue. By utilizing the depth-dependency of the attenuation coefficient, we demonstrate the ability to locate and remove the optical effects of vasculature within the upper regions of the cortex on the attenuation calculations of cortical tissue in vivo. The results of this study reveal a significant depth-dependent decrease in attenuation coefficient of nonvascular cortical tissue both ex vivo and in vivo. Regions exhibiting decreased attenuation coefficient show significant temporal correlation to regions of increased electrical activity during seizure onset and progression. This study allows for a more thorough and biologically relevant analysis of the optical signature of seizure activity in vivo using OCT.

Lanthanide-Assisted Deposition of Strongly Electro-optic PZT Thin Films on Silicon: Toward Integrated Active Nanophotonic Devices.

PubMed

George, J P; Smet, P F; Botterman, J; Bliznuk, V; Woestenborghs, W; Van Thourhout, D; Neyts, K; Beeckman, J

2015-06-24

The electro-optical properties of lead zirconate titanate (PZT) thin films depend strongly on the quality and crystallographic orientation of the thin films. We demonstrate a novel method to grow highly textured PZT thin films on silicon using the chemical solution deposition (CSD) process. We report the use of ultrathin (5-15 nm) lanthanide (La, Pr, Nd, Sm) based intermediate layers for obtaining preferentially (100) oriented PZT thin films. X-ray diffraction measurements indicate preferentially oriented intermediate Ln2O2CO3 layers providing an excellent lattice match with the PZT thin films grown on top. The XRD and scanning electron microscopy measurements reveal that the annealed layers are dense, uniform, crack-free and highly oriented (>99.8%) without apparent defects or secondary phases. The EDX and HRTEM characterization confirm that the template layers act as an efficient diffusion barrier and form a sharp interface between the substrate and the PZT. The electrical measurements indicate a dielectric constant of ∼650, low dielectric loss of ∼0.02, coercive field of 70 kV/cm, remnant polarization of 25 μC/cm(2), and large breakdown electric field of 1000 kV/cm. Finally, the effective electro-optic coefficients of the films are estimated with a spectroscopic ellipsometer measurement, considering the electric field induced variations in the phase reflectance ratio. The electro-optic measurements reveal excellent linear effective pockels coefficients of 110 to 240 pm/V, which makes the CSD deposited PZT thin film an ideal candidate for Si-based active integrated nanophotonic devices.

Photovoltaic device having light transmitting electrically conductive stacked films

DOEpatents

Weber, Michael F.; Tran, Nang T.; Jeffrey, Frank R.; Gilbert, James R.; Aspen, Frank E.

1990-07-10

A light transmitting electrically conductive stacked film, useful as a light transmitting electrode, including a first light transmitting electrically conductive layer, having a first optical thickness, a second light transmitting layer, having a second optical thickness different from the optical thickness of the first layer, and an electrically conductive metallic layer interposed between and in initimate contact with the first and second layers.

Semiconductor switch geometry with electric field shaping

DOEpatents

Booth, R.; Pocha, M.D.

1994-08-23

An optoelectric switch is disclosed that utilizes a cylindrically shaped and contoured GaAs medium or other optically active semiconductor medium to couple two cylindrically shaped metal conductors with flat and flared termination points each having an ovoid prominence centrally extending there from. Coupling the truncated ovoid prominence of each conductor with the cylindrically shaped optically active semiconductor causes the semiconductor to cylindrically taper to a triple junction circular line at the base of each prominence where the metal conductor conjoins with the semiconductor and a third medium such as epoxy or air. Tapering the semiconductor at the triple junction inhibits carrier formation and injection at the triple junction and thereby enables greater current carrying capacity through and greater sensitivity of the bulk area of the optically active medium. 10 figs.

Semiconductor switch geometry with electric field shaping

DOEpatents

Booth, Rex; Pocha, Michael D.

1994-01-01

An optoelectric switch is disclosed that utilizes a cylindrically shaped and contoured GaAs medium or other optically active semiconductor medium to couple two cylindrically shaped metal conductors with flat and flared termination points each having an ovoid prominence centrally extending there from. Coupling the truncated ovoid prominence of each conductor with the cylindrically shaped optically active semiconductor causes the semiconductor to cylindrically taper to a triple junction circular line at the base of each prominence where the metal conductor conjoins with the semiconductor and a third medium such as epoxy or air. Tapering the semiconductor at the triple junction inhibits carrier formation and injection at the triple junction and thereby enables greater current carrying capacity through and greater sensitivity of the bulk area of the optically active medium.

KSC-2013-3906

NASA Image and Video Library

2013-11-07

CAPE CANAVERAL, Fla. -- Preparations are underway to conduct a dust particle experiment for the Electrodynamic Dust Shield for Dust Mitigation project in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. The technology works by creating an electric field that propagates out like the ripples on a pond. This could prevent dust accumulation on spacesuits, thermal radiators, solar panels, optical instruments and view ports for future lunar and Mars exploration activities. CAPE CANAVERAL, Fla. -- Preparations are underway to conduct a dust particle experiment for the Electrodynamic Dust Shield for Dust Mitigation project in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. The technology works by creating an electric field that propagates out like the ripples on a pond. This could prevent dust accumulation on spacesuits, thermal radiators, solar panels, optical instruments and view ports for future lunar and Mars exploration activities.

Optically active single-walled carbon nanotubes

NASA Astrophysics Data System (ADS)

Peng, Xiaobin; Komatsu, Naoki; Bhattacharya, Sumanta; Shimawaki, Takanori; Aonuma, Shuji; Kimura, Takahide; Osuka, Atsuhiro

2007-06-01

The optical, electrical and mechanical properties of single-walled carbon nanotubes (SWNTs) are largely determined by their structures, and bulk availability of uniform materials is vital for extending their technological applications. Since they were first prepared, much effort has been directed toward selective synthesis and separation of SWNTs with specific structures. As-prepared samples of chiral SWNTs contain equal amounts of left- and right-handed helical structures, but little attention has been paid to the separation of these non-superimposable mirror image forms, known as optical isomers. Here, we show that optically active SWNT samples can be obtained by preferentially extracting either right- or left-handed SWNTs from a commercial sample. Chiral `gable-type' diporphyrin molecules bind with different affinities to the left- and right-handed helical nanotube isomers to form complexes with unequal stabilities that can be readily separated. Significantly, the diporphyrins can be liberated from the complexes afterwards, to provide optically enriched SWNTs.

Electrically tunable coherent optical absorption in graphene with ion gel.

PubMed

Thareja, Vrinda; Kang, Ju-Hyung; Yuan, Hongtao; Milaninia, Kaveh M; Hwang, Harold Y; Cui, Yi; Kik, Pieter G; Brongersma, Mark L

2015-03-11

We demonstrate electrical control over coherent optical absorption in a graphene-based Salisbury screen consisting of a single layer of graphene placed in close proximity to a gold back reflector. The screen was designed to enhance light absorption at a target wavelength of 3.2 μm by using a 600 nm-thick, nonabsorbing silica spacer layer. An ionic gel layer placed on top of the screen was used to electrically gate the charge density in the graphene layer. Spectroscopic reflectance measurements were performed in situ as a function of gate bias. The changes in the reflectance spectra were analyzed using a Fresnel based transfer matrix model in which graphene was treated as an infinitesimally thin sheet with a conductivity given by the Kubo formula. The analysis reveals that a careful choice of the ionic gel layer thickness can lead to optical absorption enhancements of up to 5.5 times for the Salisbury screen compared to a suspended sheet of graphene. In addition to these absorption enhancements, we demonstrate very large electrically induced changes in the optical absorption of graphene of ∼3.3% per volt, the highest attained so far in a device that features an atomically thick active layer. This is attributable in part to the more effective gating achieved with the ion gel over the conventional dielectric back gates and partially by achieving a desirable coherent absorption effect linked to the presence of the thin ion gel that boosts the absorption by 40%.

Electro-optical and physic-mechanical properties of colored alicyclic polyimide

NASA Astrophysics Data System (ADS)

Kravtsova, V.; Umerzakova, M.; Korobova, N.; Timoshenkov, S.; Timoshenkov, V.; Orlov, S.; Iskakov, R.; Prikhodko, O.

2016-09-01

Main optical, thermal and mechanical properties of new compositions based on alicyclic polyimide and active bright red 6C synthetic dye have been studied. It was shown that the transmission ratio of the new material in the region of 400-900 nm and 2.0 wt.% dye concentration was around 60-70%. Thermal, mechanical and electrical properties of new colored compositions were comparable with the properties of original polyimide.

Electro-optic electrodes based on Lithium Niobate Mach Zhender Interferometer Modulators for wearable bioelectric activity recording

NASA Astrophysics Data System (ADS)

Fernandes, Mariana S.; Correia, José H.; Mendes, Paulo M.

2011-05-01

Wearable devices are used to record several physiological signals, providing unobtrusive and continuous monitoring. A main challenge in these systems is to develop new recording sensors, specially envisioning bioelectric activity detection. Available devices are difficult to integrate, mainly due to the amount of electrical wires and components needed. This work proposes a fiber-optic based device, which basis of operation relies on the electro-optic effect. A Lithium Niobate (LiBnO3) Mach-Zehnder Interferometer (MZI) modulator is used as the core sensing component, followed by a signal conversion and processing stage. Tests were performed in order to validate the proposed acquisition system in terms of signal amplification and quality, stability and frequency response. A light source with a wavelength operation of 1530- 1565 nm was used. The modulated intensity is amplified and converted to an output voltage with a high transimpedance gain. The filtering and electric amplification included a 50Hz notch filter, a bandpass filter with a -3 dB bandwidth from 0.50 to 35 Hz. The obtained system performance on key elements such as sensitivity, frequency content, and signal quality, have shown that the proposed acquisition system allows the development of new wearable bioelectric monitoring solutions based on optical technologies.

Electro-optically actuated liquid-lens zoom

NASA Astrophysics Data System (ADS)

Pütsch, O.; Loosen, P.

2012-06-01

Progressive miniaturization and mass market orientation denote a challenge to the design of dynamic optical systems such as zoom-lenses. Two working principles can be identified: mechanical actuation and application of active optical components. Mechanical actuation changes the focal length of a zoom-lens system by varying the axial positions of optical elements. These systems are limited in speed and often require complex coupled movements. However, well established optical design approaches can be applied. In contrast, active optical components change their optical properties by varying their physical structure by means of applying external electric signals. An example are liquidlenses which vary their curvatures to change the refractive power. Zoom-lenses benefit from active optical components in two ways: first, no moveable structures are required and second, fast response characteristics can be realized. The precommercial development of zoom-lenses demands simplified and cost-effective system designs. However the number of efficient optical designs for electro-optically actuated zoom-lenses is limited. In this paper, the systematic development of an electro-optically actuated zoom-lens will be discussed. The application of aberration polynomials enables a better comprehension of the primary monochromatic aberrations at the lens elements during a change in magnification. This enables an enhanced synthesis of the system behavior and leads to a simplified zoom-lens design with no moving elements. The change of focal length is achieved only by varying curvatures of targeted integrated electro-optically actuated lenses.

An EBIC study of HEM polycrystalline silicon

NASA Technical Reports Server (NTRS)

Koch, T.; Ast, D.

1982-01-01

Low-cost silicon for solar cells grown by the heat exchanger method (HEM) was studied in the electron beam induced current (EBIC) mode of a scanning electron microscope (SEM). Comparisons were made between the defects observed optically and the recombination centers visible in EBIC. Much of the HEM material was single crystalline, but structural defects were found from areas near the corners of the grown material. Most of these defects consisted of linear twin boundaries and grain boundaries. The electrical activity of these boundaries was dependent on symmetry of the boundaries. Symmetric twin boundaries did not exhibit recombination activity while unsymmetric twin boundaries were electrically active.

Preparation and Properties of Nanocomposites Prepared From Shortened, Functionalized Single-Walled Carbon Nanotubes

NASA Technical Reports Server (NTRS)

Smith, J. G., Jr.; Delozier, D. M.; Watson, K. A.; Connell, J. W.; Yu, Aiping; Haddon, R. C.; Bekyarova, E.

2006-01-01

As part of a continuing materials development activity, low color space environmentally stable polymeric materials that possess sufficient electrical conductivity for electrostatic charge dissipation (ESD) have been investigated. One method of incorporating sufficient electrical conductivity for ESD without detrimental effects on other polymer properties of interest (i.e., optical and thermo-optical) is through the incorporation of single-walled carbon nanotubes (SWNTs). However, SWNTs are difficult to fully disperse in the polymer matrix. One means of improving dispersion is by shortening and functionalizing SWNTs. While this improves dispersion, other properties (i.e., electrical) of the SWNTs can be affected which can in turn alter the final nanocomposite properties. Additionally, functionalization of the polymer matrix can also influence nanocomposite properties obtained from shortened, functionalized SWNTs. The preparation and characterization of nanocomposites fabricated from a polyimide, both functionalized and unfunctionalized, and shortened, functionalized SWNTs will be presented.

Transparent and conducting ZnO films grown by spray pyrolysis

NASA Astrophysics Data System (ADS)

Hadjeris, Lazhar; Herissi, Labidi; Badreddine Assouar, M.; Easwarakhanthan, Thomas; Bougdira, Jamal; Attaf, Nadhir; Salah Aida, M.

2009-03-01

ZnO films were prepared using the simple, flexible and cost-effective spray pyrolysis technique at different substrate temperatures and precursor molarity values. The films' structural, optical and electrical properties were investigated by x-ray diffraction, UV-VIS transmittance spectroscopy, profilometry and voltage-current-temperature (VIT) measurements. The films prepared at substrate temperatures above 400 °C appear better crystallized with (0 0 2) preferred orientation and exhibit higher visible transmittance (65-80%), higher electrical n-type semiconductor conductivity (10-50 (Ω cm)-1), lower activation energy (<0.35 eV) and smaller Urbach energy (80 meV). These results indicate that such sprayed ZnO films are chemically purer and have many fewer defects and less disorder owing to an almost complete chemical decomposition of the precursor droplets. ZnO films having desired optical and electrical properties for cheaper large-area solar cells may thus be tailored through the substrate temperature and the precursor molarity.

Hybrid electro-optical nanosystem for neurons investigation

NASA Astrophysics Data System (ADS)

Miu, Mihaela; Kleps, Irina; Craciunoiu, Florea; Simion, Monica; Bragaru, Adina; Ignat, Teodora

2010-11-01

The scope of this paper is development of a new laboratory-on-a-chip (LOC) device for biomedical studies consisting of a microfluidic system coupled to microelectronic/optical transducers with nanometric features, commonly called biosensors. The proposed device is a hybrid system with sensing element on silicon (Si) chip and microfluidic system on polydimethylsiloxane (PDMS) substrates, taking into accounts their particular advantages. Different types of nanoelectrode arrays, positioned in the reactor, have been investigated as sensitive elements for electrical detection and the recording of neuron extracellular electric activity has been monitorized in parallel with whole-cell patch-clamp membrane current. Moreover, using an additional porosification process the sensing element became efficient for optical detection also. The preliminary test results demonstrate the functionality of the proposed design and also the fabrication technology, the devices bringing advantages in terms enhancement of sensitivity in both optoelectronic detection schemes.

A General Design Rule to Manipulate Photocarrier Transport Path in Solar Cells and Its Realization by the Plasmonic-Electrical Effect

NASA Astrophysics Data System (ADS)

Sha, Wei E. I.; Zhu, Hugh L.; Chen, Luzhou; Chew, Weng Cho; Choy, Wallace C. H.

2015-02-01

It is well known that transport paths of photocarriers (electrons and holes) before collected by electrodes strongly affect bulk recombination and thus electrical properties of solar cells, including open-circuit voltage and fill factor. For boosting device performance, a general design rule, tailored to arbitrary electron to hole mobility ratio, is proposed to decide the transport paths of photocarriers. Due to a unique ability to localize and concentrate light, plasmonics is explored to manipulate photocarrier transport through spatially redistributing light absorption at the active layer of devices. Without changing the active materials, we conceive a plasmonic-electrical concept, which tunes electrical properties of solar cells via the plasmon-modified optical field distribution, to realize the design rule. Incorporating spectrally and spatially configurable metallic nanostructures, thin-film solar cells are theoretically modelled and experimentally fabricated to validate the design rule and verify the plasmonic-tunable electrical properties. The general design rule, together with the plasmonic-electrical effect, contributes to the evolution of emerging photovoltaics.

Optical fiber switch

DOEpatents

Early, James W.; Lester, Charles S.

2002-01-01

Optical fiber switches operated by electrical activation of at least one laser light modulator through which laser light is directed into at least one polarizer are used for the sequential transport of laser light from a single laser into a plurality of optical fibers. In one embodiment of the invention, laser light from a single excitation laser is sequentially transported to a plurality of optical fibers which in turn transport the laser light to separate individual remotely located laser fuel ignitors. The invention can be operated electro-optically with no need for any mechanical or moving parts, or, alternatively, can be operated electro-mechanically. The invention can be used to switch either pulsed or continuous wave laser light.

Characterization of transimpedance amplifier as optical to electrical converter on designing optical instrumentation

NASA Astrophysics Data System (ADS)

Hanto, D.; Ula, R. K.

2017-05-01

Optical to electrical converter is the main components for designing of the optical instrumentations. In addition, this component is also used as signal conditioning. This component usually consists of a photo detector and amplifier. In this paper, characteristics of commercial amplifiers from Thorlabs PDA50B-EC has been observed. The experiment was conducted by diode laser with power of -5 dBm and wavelength 1310 nm; the optical attenuator to vary optical power from 0 to 60 dB, optical to electrical converter from Thorlabs Amplifier PDA50B-EC; multimode optical fiber to guide the laser; and digital voltmeter to measure the output of converter. The results of the characterization indicate that each channel amplification has a non-linear correlation between optical and electrical parameter; optical conversion measurement range of 20-23 dB to full scale; and different measurement coverage area. If this converter will be used as a part component of optical instrumentation so it should be adjusted suitably with the optical power source. Then, because of the correlation equation is not linear so calculation to determine the interpretation also should be considered in addition to the transfer function of the optical sensor.

An integrated multi-electrode-optrode array for in vitro optogenetics

PubMed Central

Welkenhuysen, Marleen; Hoffman, Luis; Luo, Zhengxiang; De Proft, Anabel; Van den Haute, Chris; Baekelandt, Veerle; Debyser, Zeger; Gielen, Georges; Puers, Robert; Braeken, Dries

2016-01-01

Modulation of a group of cells or tissue needs to be very precise in order to exercise effective control over the cell population under investigation. Optogenetic tools have already demonstrated to be of great value in the study of neuronal circuits and in neuromodulation. Ideally, they should permit very accurate resolution, preferably down to the single cell level. Further, to address a spatially distributed sample, independently addressable multiple optical outputs should be present. In current techniques, at least one of these requirements is not fulfilled. In addition to this, it is interesting to directly monitor feedback of the modulation by electrical registration of the activity of the stimulated cells. Here, we present the fabrication and characterization of a fully integrated silicon-based multi-electrode-optrode array (MEOA) for in vitro optogenetics. We demonstrate that this device allows for artifact-free electrical recording. Moreover, the MEOA was used to reliably elicit spiking activity from ChR2-transduced neurons. Thanks to the single cell resolution stimulation capability, we could determine spatial and temporal activation patterns and spike latencies of the neuronal network. This integrated approach to multi-site combined optical stimulation and electrical recording significantly advances today’s tool set for neuroscientists in their search to unravel neuronal network dynamics. PMID:26832455

Reconfigurable visible nanophotonic switch for optogenetic applications (Conference Presentation)

NASA Astrophysics Data System (ADS)

Mohanty, Aseema; Li, Qian; Tadayon, Mohammad Amin; Bhatt, Gaurang R.; Cardenas, Jaime; Miller, Steven A.; Kepecs, Adam; Lipson, Michal

2017-02-01

High spatiotemporal resolution deep-brain optical excitation for optogenetics would enable activation of specific neural populations and in-depth study of neural circuits. Conventionally, a single fiber is used to flood light into a large area of the brain with limited resolution. The scalability of silicon photonics could enable neural excitation over large areas with single-cell resolution similar to electrical probes. However, active control of these optical circuits has yet to be demonstrated for optogenetics. Here we demonstrate the first active integrated optical switch for neural excitation at 473 nm, enabling control of multiple beams for deep-brain neural stimulation. Using a silicon nitride waveguide platform, we develop a cascaded Mach-Zehnder interferometer (MZI) network located outside the brain to direct light to 8 different grating emitters located at the tip of the neural probe. We use integrated platinum microheaters to induce a local thermo-optic phase shift in the MZI to control the switch output. We measure an ON/OFF extinction ratio of >8dB for a single switch and a switching speed of 20 microseconds. We characterize the optical output of the switch by imaging its excitation of fluorescent dye. Finally, we demonstrate in vivo single-neuron optical activation from different grating emitters using a fully packaged device inserted into a mouse brain. Directly activated neurons showed robust spike firing activities with low first-spike latency and small jitter. Active switching on a nanophotonic platform is necessary for eventually controlling highly-multiplexed reconfigurable optical circuits, enabling high-resolution optical stimulation in deep-brain regions.

Ti:LiNbO3 Integrated Optic Electric-Field Sensors based on Electro-Optic Effect

NASA Astrophysics Data System (ADS)

Jung, Hongsik

2016-07-01

The need for electric-field sensing technology has widely increased, playing a critical role in various scientific and technical areas. This article comprehensively reviews and compares Ti:LiNbO3 integrated optic electric-field sensors, including the asymmetric Mach-Zehnder interferometer (MZI), 1 × 2 directional coupler (DC), and Y-fed balanced-bridge Mach-Zehnder interferometer (YBB-MZI), based on the operating principles, the electrical and optical performance, and measurements of each fabricated device. We also discuss future works to improve the sensitivity, operating stability, response speed, and bandwidth.

The time resolved measurement of ultrashort terahertz-band electric fields without an ultrashort probe

DOE Office of Scientific and Technical Information (OSTI.GOV)

Walsh, D. A., E-mail: david.walsh@stfc.ac.uk; Snedden, E. W.; Jamison, S. P.

The time-resolved detection of ultrashort pulsed THz-band electric field temporal profiles without an ultrashort laser probe is demonstrated. A non-linear interaction between a narrow-bandwidth optical probe and the THz pulse transposes the THz spectral intensity and phase information to the optical region, thereby generating an optical pulse whose temporal electric field envelope replicates the temporal profile of the real THz electric field. This optical envelope is characterised via an autocorrelation based FROG (frequency resolved optical gating) measurement, hence revealing the THz temporal profile. The combination of a narrow-bandwidth, long duration, optical probe, and self-referenced FROG makes the technique inherently immunemore » to timing jitter between the optical probe and THz pulse and may find particular application where the THz field is not initially generated via ultrashort laser methods, such as the measurement of longitudinal electron bunch profiles in particle accelerators.« less

Electrical Transfer Function and Poling Mechanisms for Nonlinear Optical Polymer Modulators

NASA Technical Reports Server (NTRS)

Watson, Michael Dale

2004-01-01

Electro-Optic Polymers hold great promise in increased electro-optic coefficients as compared to their inorganic corollaries. Many researchers have focused on quantum chemistry to describe how the dipoles respond to temperature and electric fields. Much work has also been done for single layer films to confirm these results. For optical applications, waveguide structures are utilized to guide the optical waves in 3 layer stacks. Electrode poling is the only practical poling method for these structures. This research takes an electrical engineering approach to develop poling models and electrical and optical transfer functions of the waveguide structure. The key aspect of the poling model is the large boundary charge density deposited during the poling process. The boundary charge density also has a large effect on the electrical transfer function which is used to explain the transient response of the system. These models are experimentally verified. Exploratory experiment design is used to study poling parameters including time, temperature, and voltage. These studies verify the poling conditions for CLDX/APC and CLDZ/APEC guest host electro optic polymer films in waveguide stacks predicted by the theoretical developments.

Simultaneous recording of fluorescence and electrical signals by photometric patch electrode in deep brain regions in vivo

PubMed Central

Hirai, Yasuharu; Nishino, Eri

2015-01-01

Despite its widespread use, high-resolution imaging with multiphoton microscopy to record neuronal signals in vivo is limited to the surface of brain tissue because of limited light penetration. Moreover, most imaging studies do not simultaneously record electrical neural activity, which is, however, crucial to understanding brain function. Accordingly, we developed a photometric patch electrode (PME) to overcome the depth limitation of optical measurements and also enable the simultaneous recording of neural electrical responses in deep brain regions. The PME recoding system uses a patch electrode to excite a fluorescent dye and to measure the fluorescence signal as a light guide, to record electrical signal, and to apply chemicals to the recorded cells locally. The optical signal was analyzed by either a spectrometer of high light sensitivity or a photomultiplier tube depending on the kinetics of the responses. We used the PME in Oregon Green BAPTA-1 AM-loaded avian auditory nuclei in vivo to monitor calcium signals and electrical responses. We demonstrated distinct response patterns in three different nuclei of the ascending auditory pathway. On acoustic stimulation, a robust calcium fluorescence response occurred in auditory cortex (field L) neurons that outlasted the electrical response. In the auditory midbrain (inferior colliculus), both responses were transient. In the brain-stem cochlear nucleus magnocellularis, calcium response seemed to be effectively suppressed by the activity of metabotropic glutamate receptors. In conclusion, the PME provides a powerful tool to study brain function in vivo at a tissue depth inaccessible to conventional imaging devices. PMID:25761950

Simultaneous recording of fluorescence and electrical signals by photometric patch electrode in deep brain regions in vivo.

PubMed

Hirai, Yasuharu; Nishino, Eri; Ohmori, Harunori

2015-06-01

Despite its widespread use, high-resolution imaging with multiphoton microscopy to record neuronal signals in vivo is limited to the surface of brain tissue because of limited light penetration. Moreover, most imaging studies do not simultaneously record electrical neural activity, which is, however, crucial to understanding brain function. Accordingly, we developed a photometric patch electrode (PME) to overcome the depth limitation of optical measurements and also enable the simultaneous recording of neural electrical responses in deep brain regions. The PME recoding system uses a patch electrode to excite a fluorescent dye and to measure the fluorescence signal as a light guide, to record electrical signal, and to apply chemicals to the recorded cells locally. The optical signal was analyzed by either a spectrometer of high light sensitivity or a photomultiplier tube depending on the kinetics of the responses. We used the PME in Oregon Green BAPTA-1 AM-loaded avian auditory nuclei in vivo to monitor calcium signals and electrical responses. We demonstrated distinct response patterns in three different nuclei of the ascending auditory pathway. On acoustic stimulation, a robust calcium fluorescence response occurred in auditory cortex (field L) neurons that outlasted the electrical response. In the auditory midbrain (inferior colliculus), both responses were transient. In the brain-stem cochlear nucleus magnocellularis, calcium response seemed to be effectively suppressed by the activity of metabotropic glutamate receptors. In conclusion, the PME provides a powerful tool to study brain function in vivo at a tissue depth inaccessible to conventional imaging devices. Copyright © 2015 the American Physiological Society.

Electrical and Optical Characteristics of Undoped and Se-Doped Bi2S3 Transistors

NASA Astrophysics Data System (ADS)

Kilcoyne, Colin; Alsaqqa, Ali; Rahman, Ajara A.; Whittaker-Brooks, Luisa; Sambandamurthy, G.

Semiconducting chalcogenides have been drawing increased attention due to their interesting physical properties, especially in low dimensional structures. Bi2S3 has demonstrated a high optical absorption coefficient, a large bulk mobility, small bandgap, high Seebeck coefficient, and low thermal conductivity. These properties make it a good candidate for optical, electric and thermoelectric applications. However, control over the electrical properties for enhanced thermoelectric performance and optical applications is desired. We present electrical transport and optical properties from individual nanowire and few-layer transistors of single crystalline undoped and Se-doped Bi2S3-xSex. All devices exhibit n-type semiconducting behavior and the ON/OFF ratio, mobility, and conductivity noise behavior are studied as functions of dopant concentration, temperature, and charge carrier density in different conduction regimes. The roles of dopant driven scattering mechanisms and mobility/carrier density fluctuations will be discussed. The potential for this series of materials as optical and electrical switches will be presented. NSF DMR.

Circular electrode geometry metal-semiconductor-metal photodetectors

NASA Technical Reports Server (NTRS)

Mcaddo, James A. (Inventor); Towe, Elias (Inventor); Bishop, William L. (Inventor); Wang, Liang-Guo (Inventor)

1994-01-01

The invention comprises a high speed, metal-semiconductor-metal photodetector which comprises a pair of generally circular, electrically conductive electrodes formed on an optically active semiconductor layer. Various embodiments of the invention include a spiral, intercoiled electrode geometry and an electrode geometry comprised of substantially circular, concentric electrodes which are interposed. These electrode geometries result in photodetectors with lower capacitances, dark currents and lower inductance which reduces the ringing seen in the optical pulse response.

Wide bandgap matrix switcher, amplifier and oscillator

DOEpatents

Sampayan, Stephen

2016-08-16

An electronic device comprising an optical gate, an electrical input an electrical output and a wide bandgap material positioned between the electrical input and the electrical output to control an amount of current flowing between the electrical input and the electrical output in response to a stimulus received at the optical gate can be used in wideband telecommunication applications in transmission of multi-channel signals.

Scaling vectors of attoJoule per bit modulators

NASA Astrophysics Data System (ADS)

Sorger, Volker J.; Amin, Rubab; Khurgin, Jacob B.; Ma, Zhizhen; Dalir, Hamed; Khan, Sikandar

2018-01-01

Electro-optic modulation performs the conversion between the electrical and optical domain with applications in data communication for optical interconnects, but also for novel optical computing algorithms such as providing nonlinearity at the output stage of optical perceptrons in neuromorphic analog optical computing. While resembling an optical transistor, the weak light-matter-interaction makes modulators 105 times larger compared to their electronic counterparts. Since the clock frequency for photonics on-chip has a power-overhead sweet-spot around tens of GHz, ultrafast modulation may only be required in long-distance communication, not for short on-chip links. Hence, the search is open for power-efficient on-chip modulators beyond the solutions offered by foundries to date. Here, we show scaling vectors towards atto-Joule per bit efficient modulators on-chip as well as some experimental demonstrations of novel plasmonic modulators with sub-fJ/bit efficiencies. Our parametric study of placing different actively modulated materials into plasmonic versus photonic optical modes shows that 2D materials overcompensate their miniscule modal overlap by their unity-high index change. Furthermore, we reveal that the metal used in plasmonic-based modulators not only serves as an electrical contact, but also enables low electrical series resistances leading to near-ideal capacitors. We then discuss the first experimental demonstration of a photon-plasmon-hybrid graphene-based electro-absorption modulator on silicon. The device shows a sub-1 V steep switching enabled by near-ideal electrostatics delivering a high 0.05 dB V-1 μm-1 performance requiring only 110 aJ/bit. Improving on this demonstration, we discuss a plasmonic slot-based graphene modulator design, where the polarization of the plasmonic mode aligns with graphene’s in-plane dimension; where a push-pull dual-gating scheme enables 2 dB V-1 μm-1 efficient modulation allowing the device to be just 770 nm short for 3 dB small signal modulation. Lastly, comparing the switching energy of transistors to modulators shows that modulators based on emerging materials and plasmonic-silicon hybrid integration perform on-par relative to their electronic counter parts. This in turn allows for a device-enabled two orders-of-magnitude improvement of electrical-optical co-integrated network-on-chips over electronic-only architectures. The latter opens technological opportunities in cognitive computing, dynamic data-driven applications systems, and optical analog computer engines including neuromorphic photonic computing.

Extinction-ratio-independent electrical method for measuring chirp parameters of Mach-Zehnder modulators using frequency-shifted heterodyne.

PubMed

Zhang, Shangjian; Wang, Heng; Zou, Xinhai; Zhang, Yali; Lu, Rongguo; Liu, Yong

2015-06-15

An extinction-ratio-independent electrical method is proposed for measuring chirp parameters of Mach-Zehnder electric-optic intensity modulators based on frequency-shifted optical heterodyne. The method utilizes the electrical spectrum analysis of the heterodyne products between the intensity modulated optical signal and the frequency-shifted optical carrier, and achieves the intrinsic chirp parameters measurement at microwave region with high-frequency resolution and wide-frequency range for the Mach-Zehnder modulator with a finite extinction ratio. Moreover, the proposed method avoids calibrating the responsivity fluctuation of the photodiode in spite of the involved photodetection. Chirp parameters as a function of modulation frequency are experimentally measured and compared to those with the conventional optical spectrum analysis method. Our method enables an extinction-ratio-independent and calibration-free electrical measurement of Mach-Zehnder intensity modulators by using the high-resolution frequency-shifted heterodyne technique.

Optical emission from a small scale model electric arc furnace in 250-600 nm region.

PubMed

Mäkinen, A; Niskanen, J; Tikkala, H; Aksela, H

2013-04-01

Optical emission spectroscopy has been for long proposed for monitoring and studying industrial steel making processes. Whereas the radiative decay of thermal excitations is always taking place in high temperatures needed in steel production, one of the most promising environment for such studies are electric arc furnaces, creating plasma in excited electronic states that relax with intense characteristic emission in the optical regime. Unfortunately, large industrial scale electric arc furnaces also present a challenging environment for optical emission studies and application of the method is not straightforward. To study the usability of optical emission spectroscopy in real electric arc furnaces, we have developed a laboratory scale DC electric arc furnace presented in this paper. With the setup, optical emission spectra of Fe, Cr, Cr2O3, Ni, SiO2, Al2O3, CaO, and MgO were recorded in the wavelength range 250-600 nm and the results were analyzed with the help of reference data. The work demonstrates that using characteristic optical emission, obtaining in situ chemical information from oscillating plasma of electric arc furnaces is indeed possible. In spite of complications, the method could possibly be applied to industrial scale steel making process in order to improve its efficiency.

Electro-Optic Surface Field Imaging System

DTIC Science & Technology

1989-06-01

ELECTRO - OPTIC SURFACE FIELD IMAGING SYSTEM L. E. Kingsley and W. R. Donaldson LABORATORY FOR LASER ENERGETICS University of Rochester 250 East...surface electric fields present during switch operation. The electro - optic , or Pockel’s effect, provides an extremely useful probe of surface electric...fields. Using the electro - optic effect, surface fields can be measured with an optical probe. This paper describes an electro - optic probe which is

A Surface-Coupled Optical Trap with 1-bp Precision via Active Stabilization.

PubMed

Okoniewski, Stephen R; Carter, Ashley R; Perkins, Thomas T

2017-01-01

Optical traps can measure bead motions with Å-scale precision. However, using this level of precision to infer 1-bp motion of molecular motors along DNA is difficult, since a variety of noise sources degrade instrumental stability. In this chapter, we detail how to improve instrumental stability by (1) minimizing laser pointing, mode, polarization, and intensity noise using an acousto-optical-modulator mediated feedback loop and (2) minimizing sample motion relative to the optical trap using a three-axis piezo-electric-stage mediated feedback loop. These active techniques play a critical role in achieving a surface stability of 1 Å in 3D over tens of seconds and a 1-bp stability and precision in a surface-coupled optical trap over a broad bandwidth (Δf = 0.03-2 Hz) at low force (6 pN). These active stabilization techniques can also aid other biophysical assays that would benefit from improved laser stability and/or Å-scale sample stability, such as atomic force microscopy and super-resolution imaging.

Electrically tunable superconducting terahertz metamaterial with low insertion loss and high switchable ratios

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Chun; Zhang, Caihong, E-mail: chzhang@nju.edu.cn; Hu, Guoliang

2016-07-11

With the emergence and development of artificially structured electromagnetic materials, active terahertz (THz) metamaterial devices have attracted significant attention in recent years. Tunability of transmission is desirable for many applications. For example, short-range wireless THz communications and ultrafast THz interconnects require switches and modulators. However, the tunable range of transmission amplitude of existing THz metamaterial devices is not satisfactory. In this article, we experimentally demonstrate an electrically tunable superconducting niobium nitride metamaterial device and employ a hybrid coupling model to analyze its optical transmission characteristics. The maximum transmission coefficient at 0.507 THz is 0.98 and decreases to 0.19 when themore » applied voltage increases to 0.9 V. A relative transmittance change of 80.6% is observed, making this device an efficient narrowband THz switch. Additionally, the frequency of the peak is red shifted from 0.507 to 0.425 THz, which means that the device can be used to select the frequency. This study offers an alternative tuning method to existing optical, thermal, magnetic-field, and electric-field tuning, delivering a promising approach for designing active and miniaturized THz devices.« less

Optical Input/Electrical Output Memory Elements based on a Liquid Crystalline Azobenzene Polymer.

PubMed

Mosciatti, Thomas; Bonacchi, Sara; Gobbi, Marco; Ferlauto, Laura; Liscio, Fabiola; Giorgini, Loris; Orgiu, Emanuele; Samorì, Paolo

2016-03-01

Responsive polymer materials can change their properties when subjected to external stimuli. In this work, thin films of thermotropic poly(metha)acrylate/azobenzene polymers are explored as active layer in light-programmable, electrically readable memories. The memory effect is based on the reversible modifications of the film morphology induced by the photoisomerization of azobenzene mesogenic groups. When the film is in the liquid crystalline phase, the trans → cis isomerization induces a major surface reorganization on the mesoscopic scale that is characterized by a reduction in the effective thickness of the film. The film conductivity is measured in vertical two-terminal devices in which the polymer is sandwiched between a Au contact and a liquid compliant E-GaIn drop. We demonstrate that the trans → cis isomerization is accompanied by a reversible 100-fold change in the film conductance. In this way, the device can be set in a high- or low-resistance state by light irradiation at different wavelengths. This result paves the way toward the potential use of poly(metha)acrylate/azobenzene polymer films as active layer for optical input/electrical output memory elements.

Vehicle security apparatus and method

DOEpatents

Veligdan, James T.

1996-02-13

A vehicle security apparatus for use in a motor vehicle, the apparatus comprising an optical key, a receptacle, a receiver and at least one optical fiber. The optical key has a transmitter having at least one first preprogrammed coded signal stored in a first electric circuit. The receptacle receives the optical key and at least one transmittable coded optical signal from the transmitter corresponding to the at least one preprogrammed coded signal stored in the first electric circuit. The receiver compares the at least one transmittable coded optical signal to at least one second preprogrammed coded signal stored in a second electric circuit and the receiver is adapted to trigger switching effects for at least one of enabling starting the motor vehicle and starting the motor vehicle upon determination that the at least one transmittable coded optical signal corresponds to the at least one second preprogrammed signal in the second electric circuit. The at least one optical fiber is operatively connected between the receptacle and the receiver for carrying the optical signal from the receptacle to the receiver. Also disclosed is a method for permitting only authorized use of a motor vehicle.

Analytical study of acoustically perturbed Brillouin active magnetized semiconductor plasma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shukla, Arun, E-mail: arunshuklaujn@gmail.com; Jat, K. L.

2015-07-31

An analytical study of acoustically perturbed Brillouin active magnetized semiconductor plasma has been reported. In the present analytical investigation, the lattice displacement, acousto-optical polarization, susceptibility, acousto-optical gain constant arising due to the induced nonlinear current density and acousto-optical process are deduced in an acoustically perturbed Brillouin active magnetized semiconductor plasma using the hydrodynamical model of plasma and coupled mode scheme. The influence of wave number and magnetic field has been explored. The analysis has been applied to centrosymmetric crystal. Numerical estimates are made for n-type InSb crystal duly irradiated by a frequency doubled 10.6 µm CO{sub 2} laser. It is foundmore » that lattice displacement, susceptibility and acousto-optical gain increase linearly with incident wave number and applied dc magnetic field, while decrease with scattering angle. The gain also increases with electric amplitude of incident laser beam. Results are found to be well in agreement with available literature.« less

Polarization selective phase-change nanomodulator

PubMed Central

Appavoo, Kannatassen; Haglund Jr., Richard F.

2014-01-01

Manipulating optical signals below the diffraction limit is crucial for next-generation data-storage and telecommunication technologies. Although controlling the flow of light around nanoscale waveguides was achieved over a decade ago, modulating optical signals at terahertz frequencies within nanoscale volumes remains a challenge. Since the physics underlying any modulator relies on changes in dielectric properties, the incorporation of strongly electron-correlated materials (SECMs) has been proposed because they can exhibit orders of magnitude changes in electrical and optical properties with modest thermal, electrical or optical trigger signals. Here we demonstrate a hybrid nanomodulator of deep sub-wavelength dimensions with an active volume of only 0.002 µm3 by spatially confining light on the nanometre length scale using a plasmonic nanostructure while simultaneously controlling the reactive near-field environment at its optical focus with a single, precisely positioned SECM nanostructure. Since the nanomodulator functionality hinges on this near-field electromagnetic interaction, the modulation is also selectively responsive to polarization. This architecture suggests one path for designing reconfigurable optoelectronic building blocks with responses that can be tailored with exquisite precision by varying size, geometry, and the intrinsic materials properties of the hybrid elements. PMID:25346427

Polarization selective phase-change nanomodulator

DOE PAGES

Appavoo, Kannatassen; Haglund Jr., Richard F.

2014-10-27

Manipulating optical signals below the diffraction limit is crucial for next-generation data-storage and telecommunication technologies. Although controlling the flow of light around nanoscale waveguides was achieved over a decade ago, modulating optical signals at terahertz frequencies within nanoscale volumes remains a challenge. Since the physics underlying any modulator relies on changes in dielectric properties, the incorporation of strongly electron-correlated materials (SECMs) has been proposed because they can exhibit orders of magnitude changes in electrical and optical properties with modest thermal, electrical or optical trigger signals. Here we demonstrate a hybrid nanomodulator of deep sub-wavelength dimensions with an active volume ofmore » only 0.002 µm 3 by spatially confining light on the nanometre length scale using a plasmonic nanostructure while simultaneously controlling the reactive near-field environment at its optical focus with a single, precisely positioned SECM nanostructure. Since the nanomodulator functionality hinges on this near-field electromagnetic interaction, the modulation is also selectively responsive to polarization. Lastly, this architecture suggests one path for designing reconfigurable optoelectronic building blocks with responses that can be tailored with exquisite precision by varying size, geometry, and the intrinsic materials properties of the hybrid elements.« less

Combined heat and power generation with a HCPV system at 2000 suns

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paredes, Filippo; Montagnino, Fabio M.; Milone, Sergio

2015-09-28

This work shows the development of an innovative solar CHP system for the combined production of heat and power based upon HCPV modules working at the high concentration level of 2000 suns. The solar radiation is concentrated on commercial InGaP/InGaAs/Ge triple-junction solar cells designed for intensive work. The primary optics is a rectangular off-axis parabolic mirror while a secondary optic at the focus of the parabolic mirror is glued in optical contact with the cell. Each module consist of 2 axis tracker (Alt-Alt type) with 20 multijunction cells each one integrated with an active heat sink. The cell is connectedmore » to an active heat transfer system that allows to keep the cell at a high level of electrical efficiency (ηel > 30 %), bringing the heat transfer fluid (water and glycol) up to an output temperature of 90°C. Accordingly with the experimental data collected from the first 1 kWe prototype, the total amount of extracted thermal energy is above the 50% of the harvested solar radiation. That, in addition the electrical efficiency of the system contributes to reach an overall CHP efficiency of more than the 80%.« less

Combined heat and power generation with a HCPV system at 2000 suns

NASA Astrophysics Data System (ADS)

Paredes, Filippo; Montagnino, Fabio M.; Salinari, Piero; Bonsignore, Gaetano; Milone, Sergio; Agnello, Simonpietro; Barbera, Marco; Gelardi, Franco M.; Sciortino, Luisa; Collura, Alfonso; Lo Cicero, Ugo; Cannas, Marco

2015-09-01

This work shows the development of an innovative solar CHP system for the combined production of heat and power based upon HCPV modules working at the high concentration level of 2000 suns. The solar radiation is concentrated on commercial InGaP/InGaAs/Ge triple-junction solar cells designed for intensive work. The primary optics is a rectangular off-axis parabolic mirror while a secondary optic at the focus of the parabolic mirror is glued in optical contact with the cell. Each module consist of 2 axis tracker (Alt-Alt type) with 20 multijunction cells each one integrated with an active heat sink. The cell is connected to an active heat transfer system that allows to keep the cell at a high level of electrical efficiency (ηel > 30 %), bringing the heat transfer fluid (water and glycol) up to an output temperature of 90°C. Accordingly with the experimental data collected from the first 1 kWe prototype, the total amount of extracted thermal energy is above the 50% of the harvested solar radiation. That, in addition the electrical efficiency of the system contributes to reach an overall CHP efficiency of more than the 80%.

Power system applications of fiber optic sensors

NASA Technical Reports Server (NTRS)

Johnston, A. R.; Jackson, S. P.; Kirkham, H.; Yeh, C.

1986-01-01

This document is a progress report of work done in 1985 on the Communications and Control for Electric Power Systems Project at the Jet Propulsion Laboratory. These topics are covered: Electric Field Measurement, Fiber Optic Temperature Sensing, and Optical Power transfer. Work was done on the measurement of ac and dc electric fields. A prototype sensor for measuring alternating fields was made using a very simple electroscope approach. An electronic field mill sensor for dc fields was made using a fiber optic readout, so that the entire probe could be operated isolated from ground. There are several instances in which more precise knowledge of the temperature of electrical power apparatus would be useful. This report describes a number of methods whereby the distributed temperature profile can be obtained using a fiber optic sensor. The ability to energize electronics by means of an optical fiber has the advantage that electrical isolation is maintained at low cost. In order to accomplish this, it is necessary to convert the light energy into electrical form by means of photovoltaic cells. JPL has developed an array of PV cells in gallium arsenide specifically for this purpose. This work is described.

Preparation of TiO2/Ag/TiO2 (TAT) multilayer films with optical and electrical properties enhanced by using Cr-added Ag film

NASA Astrophysics Data System (ADS)

Loka, Chadrasekhar; Lee, Kee-Sun

2017-09-01

The dielectric-metal-dielectric tri-layer films have attracted much attention by virtue of their low-cost and high quality device performance as a transparent conductive electrode. Here, we report the deposition of Cr doped Ag films sandwiched between thin TiO2 layers and investigation on the surface microstructure, optical and electrical properties depending on the thickness of the Ag(Cr). The activation energy (1.18 eV) for grain growth of Ag was calculated from the Arrhenius plot using the law Dn -D0n = kt , which was comparable to the bulk diffusion of Ag. This result indicated the grain growth of Ag was effectively retarded by the Cr addition, which was presumed to related with blocking the surface and grain boundary diffusion due to Cr segregation. Based on thermal stability of Cr added Ag film, we deposited TiO2/Ag(Cr)/TiO2 (TAT) multilayer thin films and with a 10 nm thick Ag(Cr), the TAT films showed high optical transmittance in the visible region (94.2%), low electrical resistivity (8.66 × 10-5 Ω cm), and hence the high figure of merit 57.15 × 10-3 Ω-1 was achieved. The high transmittance of the TAT film was believed to be attributed to the low optical loss due to a reduction in the Ag layer thickness, the surface plasmon effect, and the electron scattering reduced by the Ag layer with a low electrical resistivity.

A new multicomponent salt of imidazole and tetrabromoterepthalic acid: structural, optical, thermal, electrical transport properties and antibacterial activity along with Hirshfeld surface analysis.

PubMed

Dey, Sanjoy Kumar; Saha, Rajat; Singha, Soumen; Biswas, Susobhan; Layek, Animesh; Middya, Somnath; Ray, Partha Pratim; Bandhyopadhyay, Debasis; Kumar, Sanjay

2015-06-05

Herein, we report the structural, optical, thermal and electrical transport properties of a new multicomponent salt (TBTA(2-))·2(IM(+))·(water) [TBTA-IM] of tetrabromoterepthalic acid (TBTA) with imidazole (IM). The crystal structure of TBTA-IM is determined by both the single crystal and powder X-ray diffraction techniques. The structural analysis has revealed that the supramolecular charge assisted O(-)⋯HN(+) hydrogen bonding and Br⋯π interactions play the most vital role in formation of this multicomponent supramolecular assembly. The Hirshfeld surface analysis has been carried out to investigate supramolecular interactions and associated 2D fingerprint plots reveal the relative contribution of these interactions in the crystal structure quantitatively. According to theoretical analysis the HOMO-LUMO energy gap of the salt is 2.92 eV. The salt has been characterized by IR, UV-vis and photoluminescence spectroscopic studies. It shows direct optical transition with band gaps of 4.1 eV, which indicates that the salt is insulating in nature. The photoluminescence spectrum of the salt is significantly different from that of TBTA. Further, a comparative study on the antibacterial activity of the salt with respect to imidazole, Gatifloxacin and Ciprofloxacin has been performed. Moreover, the current-voltage (I-V) characteristic of ITO/TBTA-IM/Al sandwich structure exhibits good rectifying property and the electron tunneling process governs the electrical transport mechanism of the device. Copyright © 2015 Elsevier B.V. All rights reserved.

Detection of Optogenetic Stimulation in Somatosensory Cortex by Non-Human Primates - Towards Artificial Tactile Sensation

PubMed Central

Brush, Benjamin; Borton, David; Wagner, Fabien; Agha, Naubahar; Sheinberg, David L.; Nurmikko, Arto V.

2014-01-01

Neuroprosthesis research aims to enable communication between the brain and external assistive devices while restoring lost functionality such as occurs from stroke, spinal cord injury or neurodegenerative diseases. In future closed-loop sensorimotor prostheses, one approach is to use neuromodulation as direct stimulus to the brain to compensate for a lost sensory function and help the brain to integrate relevant information for commanding external devices via, e.g. movement intention. Current neuromodulation techniques rely mainly of electrical stimulation. Here we focus specifically on the question of eliciting a biomimetically relevant sense of touch by direct stimulus of the somatosensory cortex by introducing optogenetic techniques as an alternative to electrical stimulation. We demonstrate that light activated opsins can be introduced to target neurons in the somatosensory cortex of non-human primates and be optically activated to create a reliably detected sensation which the animal learns to interpret as a tactile sensation localized within the hand. The accomplishment highlighted here shows how optical stimulation of a relatively small group of mostly excitatory somatosensory neurons in the nonhuman primate brain is sufficient for eliciting a useful sensation from data acquired by simultaneous electrophysiology and from behavioral metrics. In this first report to date on optically neuromodulated behavior in the somatosensory cortex of nonhuman primates we do not yet dissect the details of the sensation the animals exerience or contrast it to those evoked by electrical stimulation, issues of considerable future interest. PMID:25541938

Frequency-doubled vertical-external-cavity surface-emitting laser

DOEpatents

Raymond, Thomas D.; Alford, William J.; Crawford, Mary H.; Allerman, Andrew A.

2002-01-01

A frequency-doubled semiconductor vertical-external-cavity surface-emitting laser (VECSEL) is disclosed for generating light at a wavelength in the range of 300-550 nanometers. The VECSEL includes a semiconductor multi-quantum-well active region that is electrically or optically pumped to generate lasing at a fundamental wavelength in the range of 600-1100 nanometers. An intracavity nonlinear frequency-doubling crystal then converts the fundamental lasing into a second-harmonic output beam. With optical pumping with 330 milliWatts from a semiconductor diode pump laser, about 5 milliWatts or more of blue light can be generated at 490 nm. The device has applications for high-density optical data storage and retrieval, laser printing, optical image projection, chemical-sensing, materials processing and optical metrology.

Thickness dependent charge transfer states and dark carriers density in vacuum deposited small molecule organic photocell

NASA Astrophysics Data System (ADS)

Shekhar, Himanshu; Tzabari, Lior; Solomeshch, Olga; Tessler, Nir

2016-10-01

We have investigated the influence of the active layer thickness on the balance of the internal mechanisms affecting the efficiency of copper phthalocyanine - fullerene (C60) based vacuum deposited bulk heterojunction organic photocell. We fabricated a range of devices for which we varied the thickness of the active layer from 40 to 120 nm and assessed their performance using optical and electrical characterization techniques. As reported previously for phthalocyanine:C60, the performance of the device is highly dependent on the active layer thickness and of all the thicknesses we tried, the 40 nm thin active layer device showed the best solar cell characteristic parameters. Using the transfer matrix based optical model, which includes interference effects, we calculated the optical power absorbed in the active layers for the entire absorption band, and we found that this cannot explain the trend with thickness. Measurement of the cell quantum efficiency as a function of light intensity showed that the relative weight of the device internal processes changes when going from 40 nm to 120 nm thick active layer. Electrical modeling of the device, which takes different internal processes into account, allowed to quantify the changes in the processes affecting the generation - recombination balance. Sub gap external quantum efficiency and morphological analysis of the surface of the films agree with the model's result. We found that as the thickness grows the density of charge transfer states and of dark carriers goes up and the uniformity in the vertical direction is reduced.

Photonic-powered cable assembly

DOEpatents

Sanderson, Stephen N.; Appel, Titus James; Wrye, IV, Walter C.

2013-01-22

A photonic-cable assembly includes a power source cable connector ("PSCC") coupled to a power receive cable connector ("PRCC") via a fiber cable. The PSCC electrically connects to a first electronic device and houses a photonic power source and an optical data transmitter. The fiber cable includes an optical transmit data path coupled to the optical data transmitter, an optical power path coupled to the photonic power source, and an optical feedback path coupled to provide feedback control to the photonic power source. The PRCC electrically connects to a second electronic device and houses an optical data receiver coupled to the optical transmit data path, a feedback controller coupled to the optical feedback path to control the photonic power source, and a photonic power converter coupled to the optical power path to convert photonic energy received over the optical power path to electrical energy to power components of the PRCC.

Photonic-powered cable assembly

DOEpatents

Sanderson, Stephen N; Appel, Titus James; Wrye, IV, Walter C

2014-06-24

A photonic-cable assembly includes a power source cable connector ("PSCC") coupled to a power receive cable connector ("PRCC") via a fiber cable. The PSCC electrically connects to a first electronic device and houses a photonic power source and an optical data transmitter. The fiber cable includes an optical transmit data path coupled to the optical data transmitter, an optical power path coupled to the photonic power source, and an optical feedback path coupled to provide feedback control to the photonic power source. The PRCC electrically connects to a second electronic device and houses an optical data receiver coupled to the optical transmit data path, a feedback controller coupled to the optical feedback path to control the photonic power source, and a photonic power converter coupled to the optical power path to convert photonic energy received over the optical power path to electrical energy to power components of the PRCC.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wendt, Joel Robert; Hadley, G. Ronald; Samora, Sally

Plasmonic structures open up new opportunities in photonic devices, sometimes offering an alternate method to perform a function and sometimes offering capabilities not possible with standard optics. In this LDRD we successfully demonstrated metal coatings on optical surfaces that do not adversely affect the transmission of those surfaces at the design frequency. This technology could be applied as an RF noise blocking layer across an optical aperture or as a method to apply an electric field to an active electro-optic device without affecting optical performance. We also demonstrated thin optical absorbers using similar patterned surfaces. These infrared optical antennas showmore » promise as a method to improve performance in mercury cadmium telluride detectors. Furthermore, these structures could be coupled with other components to lead to direct rectification of infrared radiation. This possibility leads to a new method for infrared detection and energy harvesting of infrared radiation.« less

Nanostructured Gd3+-TiO2 surfaces for self-cleaning application

NASA Astrophysics Data System (ADS)

Saif, M.; El-Molla, S. A.; Aboul-Fotouh, S. M. K.; Ibrahim, M. M.; Ismail, L. F. M.; Dahn, Douglas C.

2014-06-01

Preparation of self-cleaning surfaces based on lanthanide modified titanium dioxide nanoparticles has rarely been reported. In the present work, gadolinium doped titanium dioxide thin films (x mol Gd3+-TiO2 where x = 0.000, 0.005, 0.008, 0.010, 0.020 and 0.030 mol) were synthesized by sol-gel method and deposited using doctor-blade method. These films were characterized by studying their structural, optical and electrical properties. Doping with gadolinium decreases the band gap energy and increase conductivity of thin films. The photo self-cleaning activity in term of quantitative determination of the active oxidative species (rad OH) produced on the thin film surfaces was evaluated using fluorescent probe method. The results show that, the highly active thin film is the 0.020 Gd3+-TiO2. The structural, morphology, optical, electrical and photoactivity properties of Gd3+-TiO2 thin films make it promising surfaces for self-cleaning application. Mineralization of commercial textile dye (Remazol Red RB-133, RR) and durability using 0.020Gd3+-TiO2 film surface was studied.

Thin film ferroelectric electro-optic memory

NASA Technical Reports Server (NTRS)

Thakoor, Sarita (Inventor); Thakoor, Anilkumar P. (Inventor)

1993-01-01

An electrically programmable, optically readable data or memory cell is configured from a thin film of ferroelectric material, such as PZT, sandwiched between a transparent top electrode and a bottom electrode. The output photoresponse, which may be a photocurrent or photo-emf, is a function of the product of the remanent polarization from a previously applied polarization voltage and the incident light intensity. The cell is useful for analog and digital data storage as well as opto-electric computing. The optical read operation is non-destructive of the remanent polarization. The cell provides a method for computing the product of stored data and incident optical data by applying an electrical signal to store data by polarizing the thin film ferroelectric material, and then applying an intensity modulated optical signal incident onto the thin film material to generate a photoresponse therein related to the product of the electrical and optical signals.

Optical scanning tests of complex CMOS microcircuits

NASA Technical Reports Server (NTRS)

Levy, M. E.; Erickson, J. J.

1977-01-01

The new test method was based on the use of a raster-scanned optical stimulus in combination with special electrical test procedures. The raster-scanned optical stimulus was provided by an optical spot scanner, an instrument that combines a scanning optical microscope with electronic instrumentation to process and display the electric photoresponse signal induced in a device that is being tested.

Auditory responses to electric and infrared neural stimulation of the rat cochlear nucleus.

PubMed

Verma, Rohit U; Guex, Amélie A; Hancock, Kenneth E; Durakovic, Nedim; McKay, Colette M; Slama, Michaël C C; Brown, M Christian; Lee, Daniel J

2014-04-01

In an effort to improve the auditory brainstem implant, a prosthesis in which user outcomes are modest, we applied electric and infrared neural stimulation (INS) to the cochlear nucleus in a rat animal model. Electric stimulation evoked regions of neural activation in the inferior colliculus and short-latency, multipeaked auditory brainstem responses (ABRs). Pulsed INS, delivered to the surface of the cochlear nucleus via an optical fiber, evoked broad neural activation in the inferior colliculus. Strongest responses were recorded when the fiber was placed at lateral positions on the cochlear nucleus, close to the temporal bone. INS-evoked ABRs were multipeaked but longer in latency than those for electric stimulation; they resembled the responses to acoustic stimulation. After deafening, responses to electric stimulation persisted, whereas those to INS disappeared, consistent with a reported "optophonic" effect, a laser-induced acoustic artifact. Thus, for deaf individuals who use the auditory brainstem implant, INS alone did not appear promising as a new approach. Copyright © 2014 Elsevier B.V. All rights reserved.

Auditory Responses to Electric and Infrared Neural Stimulation of the Rat Cochlear Nucleus

PubMed Central

Verma, Rohit; Guex, Amelie A.; Hancock, Kenneth E.; Durakovic, Nedim; McKay, Colette M.; Slama, Michaël C. C.; Brown, M. Christian; Lee, Daniel J.

2014-01-01

In an effort to improve the auditory brainstem implant, a prosthesis in which user outcomes are modest, we applied electric and infrared neural stimulation (INS) to the cochlear nucleus in a rat animal model. Electric stimulation evoked regions of neural activation in the inferior colliculus and short-latency, multipeaked auditory brainstem responses (ABRs). Pulsed INS, delivered to the surface of the cochlear nucleus via an optical fiber, evoked broad neural activation in the inferior colliculus. Strongest responses were recorded when the fiber was placed at lateral positions on the cochlear nucleus, close to the temporal bone. INS-evoked ABRs were multipeaked but longer in latency than those for electric stimulation; they resembled the responses to acoustic stimulation. After deafening, responses to electric stimulation persisted, whereas those to INS disappeared, consistent with a reported “optophonic” effect, a laser-induced acoustic artifact. Thus, for deaf individuals who use the auditory brainstem implant, INS alone did not appear promising as a new approach. PMID:24508368

Structural, optical and high pressure electrical resistivity studies of pure NiO and Cu-doped NiO nanoparticles

NASA Astrophysics Data System (ADS)

Marselin, M. Abila; Jaya, N. Victor

2016-04-01

In this paper, pure NiO and Cu-doped NiO nanoparticles are prepared by co-precipitation method. The electrical resistivity measurements by applying high pressure on pure NiO and Cu-doped NiO nanoparticles were reported. The Bridgman anvil set up is used to measure high pressures up to 8 GPa. These measurements show that there is no phase transformation in the samples till the high pressure is reached. The samples show a rapid decrease in electrical resistivity up to 5 GPa and it remains constant beyond 5 GPa. The electrical resistivity and the transport activation energy of the samples under high pressure up to 8 GPa have been studied in the temperature range of 273-433 K using diamond anvil cell. The temperature versus electrical resistivity studies reveal that the samples behave like a semiconductor. The activation energies of the charge carriers depend on the size of the samples.

Non-invasive red light optogenetic pacing and optical coherence microscopy (OCM) imaging for drosophila melanogaster (Conference Presentation)

NASA Astrophysics Data System (ADS)

Men, Jing; Li, Airong; Jerwick, Jason; Tanzi, Rudolph E.; Zhou, Chao

2017-02-01

Cardiac pacing could be a powerful tool for investigating mammalian cardiac electrical conduction systems as well as for treatment of certain cardiac pathologies. However, traditional electrical pacing using pacemaker requires an invasive surgical procedure. Electrical currents from the implanted electrodes can also cause damage to heart tissue, further restricting its utility. Optogenetic pacing has been developed as a promising, non-invasive alternative to electrical stimulation for controlling animal heart rhythms. It induces heart contractions by shining pulsed light on transgene-generated microbial opsins, which in turn activate the light gated ion channels in animal hearts. However, commonly used opsins in optogenetic pacing, such as channelrhodopsin-2 (ChR2), require short light wavelength stimulation (475 nm), which is strongly absorbed and scattered by tissue. Here, we performed optogenetic pacing by expression of recently engineered red-shifted microbial opsins, ReaChR and CsChrimson, in a well-established animal model, Drosophila melanogaster, using the 617 nm stimulation light pulses. The OCM technique enables non-invasive optical imaging of animal hearts with high speed and ultrahigh axial and transverse resolutions. We integrated a customized OCM system with the optical stimulation system to monitor the optogenetic pacing noninvasively. The use of red-sifted opsins enabled deeper penetration of simulating light at lower power, which is promising for applications of optogenetic pacing in mammalian cardiac pathology studies or clinical treatments in the future.

Local transmural action potential gradients are absent in the isolated, intact dog heart but present in the corresponding coronary-perfused wedge.

PubMed

Boukens, Bastiaan J; Meijborg, Veronique M F; Belterman, Charly N; Opthof, Tobias; Janse, Michiel J; Schuessler, Richard B; Coronel, Ruben; Efimov, Igor R

2017-05-01

The left ventricular (LV) coronary-perfused canine wedge preparation is a model commonly used for studying cardiac repolarization. In wedge studies, transmembrane potentials typically are recorded; whereas, extracellular electrical recordings are commonly used in intact hearts. We compared electrically measured activation recovery interval (ARI) patterns in the intact heart with those recorded at the same location in the LV wedge preparation. We also compared electrically recorded and optically obtained ARIs in the LV wedge preparation. Five Langendorff-perfused canine hearts were paced from the right atrium. Local activation and repolarization times were measured with eight transmural needle electrodes. Subsequently, left ventricular coronary-perfused wedge preparations were prepared from these hearts while the electrodes remained in place. Three electrodes remained at identical positions as in the intact heart. Both electrograms and optical action potentials were recorded (pacing cycle length 400-4000 msec) and activation and repolarization patterns were analyzed. ARIs found in the subepicardium were shorter than in the subendocardium in the LV wedge preparation but not in the intact heart. The transmural ARI gradient recorded at the cut surface of the wedge was not different from that recorded internally. ARIs recorded internally and at the cut surface in the LV wedge preparation, both correlated with optically recorded action potentials. ARI and RT gradients in the LV wedge preparation differed from those in the intact canine heart, implying that those observations in human LV wedge preparations also should be extrapolated to the intact human heart with caution. © 2017 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahnood, Arman, E-mail: arman.ahnood@unimelb.edu.au; Ganesan, Kumaravelu; Stacey, Alastair

Beyond conventional electrically-driven neuronal stimulation methods, there is a growing interest in optically-driven approaches. In recent years, nitrogen-doped ultrananocrystalline diamond (N-UNCD) has emerged as a strong material candidate for use in electrically-driven stimulation electrodes. This work investigates the electrochemical activity of N-UNCD in response to pulsed illumination, to assess its potential for use as an optically-driven stimulation electrode. Whilst N-UNCD in the as-grown state exhibits a weak photoresponse, the oxygen plasma treated film exhibits two orders of magnitude enhancement in its sub-bandgap open circuit photovoltage response. The enhancement is attributed to the formation of a dense network of oxygen-terminated diamondmore » nanocrystals at the N-UNCD surface. Electrically connected to the N-UNCD bulk via sub-surface graphitic grain boundaries, these diamond nanocrystals introduce a semiconducting barrier between the sub-surface graphitic semimetal and the electrolyte solution, leading to a photovoltage under irradiation with wavelengths of λ = 450 nm and shorter. Within the safe optical exposure limit of 2 mW mm{sup −2}, charge injection capacity of 0.01 mC cm{sup −2} is achieved using a 15 × 15 μm electrode, meeting the requirements for extracellular and intercellular stimulation. The nanoscale nature of processes presented here along with the diamond's biocompatibility and biostability open an avenue for the use of oxygen treated N-UNCD as optically driven stimulating electrodes.« less

Effects of anhydrous AlCl3 dopant on the structural, optical and electrical properties of PVA-PVP polymer composite films

NASA Astrophysics Data System (ADS)

Shanmugam, G.; Krishnakumar, V.

2018-05-01

Polymer composite films based on PVA-PVP with AlCl3 as the dopant at different concentrations were prepared using solution casting technique. XRD patterns reveal the increase in amorphousity of the films with AlCl3 doping. Optical absorption studies exhibit that the values of optical absorption coefficient, direct and indirect optical band gaps are found to decrease with increase in AlCl3 concentration. It confirms the charge transfer in complexes between the polymer and the dopant. The dielectric studies show the increase in dielectric constant at low frequency with increasing AlCl3 concentration and temperature. The ac conductivity and ionic conductivity increase with the AlCl3 content and the maximum value at room temperature is found to be 6.89 × 10-4 and 8.05 × 10-5 S/cm for higher AlCl3 doped PVA-PVP film. The estimated ionic conductivity value is three or four orders of magnitude greater than those obtained in the certain representative polymer-salt complexes as reported earlier. Electrical modulus plots confirm the removal of electrode polarization and the low conductivity relaxation time with Al doping. The activation energy estimated from the temperature dependent dc conductivity plot is agreed well with the migration energy calculated from the temperature dependent electric modulus plot.

Transient photoresponse of nitrogen-doped ultrananocrystalline diamond electrodes in saline solution

NASA Astrophysics Data System (ADS)

Ahnood, Arman; Simonov, Alexandr N.; Laird, Jamie S.; Maturana, Matias I.; Ganesan, Kumaravelu; Stacey, Alastair; Ibbotson, Michael R.; Spiccia, Leone; Prawer, Steven

2016-03-01

Beyond conventional electrically-driven neuronal stimulation methods, there is a growing interest in optically-driven approaches. In recent years, nitrogen-doped ultrananocrystalline diamond (N-UNCD) has emerged as a strong material candidate for use in electrically-driven stimulation electrodes. This work investigates the electrochemical activity of N-UNCD in response to pulsed illumination, to assess its potential for use as an optically-driven stimulation electrode. Whilst N-UNCD in the as-grown state exhibits a weak photoresponse, the oxygen plasma treated film exhibits two orders of magnitude enhancement in its sub-bandgap open circuit photovoltage response. The enhancement is attributed to the formation of a dense network of oxygen-terminated diamond nanocrystals at the N-UNCD surface. Electrically connected to the N-UNCD bulk via sub-surface graphitic grain boundaries, these diamond nanocrystals introduce a semiconducting barrier between the sub-surface graphitic semimetal and the electrolyte solution, leading to a photovoltage under irradiation with wavelengths of λ = 450 nm and shorter. Within the safe optical exposure limit of 2 mW mm-2, charge injection capacity of 0.01 mC cm-2 is achieved using a 15 × 15 μm electrode, meeting the requirements for extracellular and intercellular stimulation. The nanoscale nature of processes presented here along with the diamond's biocompatibility and biostability open an avenue for the use of oxygen treated N-UNCD as optically driven stimulating electrodes.

Optical magnetic mirrors without metals

DOE PAGES

Liu, Sheng; Sinclair, Michael B.; Mahony, Thomas S.; ...

2014-01-01

The reflection of an optical wave from metal, arising from strong interactions between the optical electric field and the free carriers of the metal, is accompanied by a phase reversal of the reflected electric field. A far less common route to achieving high reflectivity exploits strong interactions between the material and the optical magnetic field to produce a “magnetic mirror” that does not reverse the phase of the reflected electric field. At optical frequencies, the magnetic properties required for strong interaction can be achieved only by using artificially tailored materials. Here, we experimentally demonstrate, for the first time to themore » best of our knowledge, the magnetic mirror behavior of a low-loss all-dielectric metasurface at infrared optical frequencies through direct measurements of the phase and amplitude of the reflected optical wave. The enhanced absorption and emission of transverse-electric dipoles placed close to magnetic mirrors can lead to exciting new advances in sensors, photodetectors, and light sources.« less

Implantable optoelectronic probes for in vivo optogenetics.

PubMed

Iseri, Ege; Kuzum, Duygu

2017-06-01

More than a decade has passed since optics and genetics came together and lead to the emerging technologies of optogenetics. The advent of light-sensitive opsins made it possible to optically trigger the neurons into activation or inhibition by using visible light. The importance of spatiotemporally isolating a segment of a neural network and controlling nervous signaling in a precise manner has driven neuroscience researchers and engineers to invest great efforts in designing high precision in vivo implantable devices. These efforts have focused on delivery of sufficient power to deep brain regions, while monitoring neural activity with high resolution and fidelity. In this review, we report the progress made in the field of hybrid optoelectronic neural interfaces that combine optical stimulation with electrophysiological recordings. Different approaches that incorporate optical or electrical components on implantable devices are discussed in detail. Advantages of various different designs as well as practical and fundamental limitations are summarized to illuminate the future of neurotechnology development.

Overview of the Systems Special Investigation Group investigation

NASA Technical Reports Server (NTRS)

Mason, James B.; Dursch, Harry; Edelman, Joel

1993-01-01

The Long Duration Exposure Facility (LDEF) carried a remarkable variety of electrical, mechanical, thermal, and optical systems, subsystems, and components. Nineteen of the fifty-seven experiments flown on LDEF contained functional systems that were active on-orbit. Almost all of the other experiments possessed at least a few specific components of interest to the Systems Special Investigation Group (Systems SIG), such as adhesives, seals, fasteners, optical components, and thermal blankets. Almost all top level functional testing of the active LDEF and experiment systems has been completed. Failure analysis of both LDEF hardware and individual experiments that failed to perform as designed has also been completed. Testing of system components and experimenter hardware of interest to the Systems SIG is ongoing. All available testing and analysis results were collected and integrated by the Systems SIG. An overview of our findings is provided. An LDEF Optical Experiment Database containing information for all 29 optical related experiments is also discussed.

Optics Communications: Special issue on Polymer Photonics and Its Applications

NASA Astrophysics Data System (ADS)

Zhang, Ziyang; Pitwon, Richard C. A.; Feng, Jing

2016-03-01

In the last decade polymer photonics has witnessed a tremendous boost in research efforts and practical applications. Polymer materials can be engineered to exhibit unique optical and electrical properties. Extremely transparent and reliable passive optical polymers have been made commercially available and paved the ground for the development of various waveguide components. Advancement in the research activities regarding the synthesis of active polymers has enabled devices such as ultra-fast electro-optic modulators, efficient white light emitting diodes, broadband solar cells, flexible displays, and so on. The fabrication technology is not only fast and cost-effective, but also provides flexibility and broad compatibility with other semiconductor processing technologies. Reports show that polymers have been integrated in photonic platforms such as silicon-on-insulator (SOI), III-V semiconductors, and silica PLCs, and vice versa, photonic components made from a multitude of materials have been integrated, in a heterogeneous/hybrid manner, in polymer photonic platforms.

Implantable optoelectronic probes for in vivo optogenetics

NASA Astrophysics Data System (ADS)

Iseri, Ege; Kuzum, Duygu

2017-06-01

More than a decade has passed since optics and genetics came together and lead to the emerging technologies of optogenetics. The advent of light-sensitive opsins made it possible to optically trigger the neurons into activation or inhibition by using visible light. The importance of spatiotemporally isolating a segment of a neural network and controlling nervous signaling in a precise manner has driven neuroscience researchers and engineers to invest great efforts in designing high precision in vivo implantable devices. These efforts have focused on delivery of sufficient power to deep brain regions, while monitoring neural activity with high resolution and fidelity. In this review, we report the progress made in the field of hybrid optoelectronic neural interfaces that combine optical stimulation with electrophysiological recordings. Different approaches that incorporate optical or electrical components on implantable devices are discussed in detail. Advantages of various different designs as well as practical and fundamental limitations are summarized to illuminate the future of neurotechnology development.

Optoelectronic device with nanoparticle embedded hole injection/transport layer

DOEpatents

Wang, Qingwu [Chelmsford, MA; Li, Wenguang [Andover, MA; Jiang, Hua [Methuen, MA

2012-01-03

An optoelectronic device is disclosed that can function as an emitter of optical radiation, such as a light-emitting diode (LED), or as a photovoltaic (PV) device that can be used to convert optical radiation into electrical current, such as a photovoltaic solar cell. The optoelectronic device comprises an anode, a hole injection/transport layer, an active layer, and a cathode, where the hole injection/transport layer includes transparent conductive nanoparticles in a hole transport material.

Design of Hybrid Silicon and Lithium Niobate Active Region for Electro-optical Modulation

DTIC Science & Technology

2017-03-01

bandwidth our group has proposed a Mach-Zehnder traveling -wave type modulator with optimized cross section dimensions using a similar material stack as...increases the electric field intensity available to the Pockel’s effect. At the same time , the induced metal loss increases as the electrodes become...Gopalakrishnan et al., “Performance and modeling of broadband LiNbO3 traveling wave optical intensity modulators,” J. Light. Technol., vol. 12, no. 10, pp

Electrical transport in AZO nanorods

NASA Astrophysics Data System (ADS)

Yildiz, A.; Cansizoglu, H.; Karabacak, T.

2015-10-01

Al-doped ZnO (AZO) nanorods (NRs) with different lengths were deposited by utilizing glancing angle deposition (GLAD) technique in a DC sputter system at room temperature. The structural and optical characteristics of the NRs were investigated by the X-ray diffraction (XRD), scanning electron microscopy (SEM), and UV-vis-NIR spectroscopy measurements. A band gap of about 3.5 eV was observed for the NRs. A novel capping process utilizing varying deposition angles was used to introduce a blanket metal top contact for the electrical characterization of NRs. Current-voltage (I-V) measurements were used to properly evaluate the approximate resistivity of a single NR. The electrical conduction was found to be governed by the thermally activated transport mechanism. Activation energy was determined as 0.14 eV from temperature dependent resistivity data.

46 CFR 111.60-6 - Fiber optic cable.

Code of Federal Regulations, 2010 CFR

2010-10-01

... 46 Shipping 4 2010-10-01 2010-10-01 false Fiber optic cable. 111.60-6 Section 111.60-6 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-6 Fiber optic cable. Each fiber optic cable must— (a) Be...

Small, Optically-Driven Power Source

NASA Technical Reports Server (NTRS)

Cockrum, Richard H.; Wang, Ke-Li J.

1988-01-01

Power transmitted along fiber-optic cables. Transmitted as infrared light along fiber-optic cable, converted to electricity to supply small electronic circuit. Power source and circuit remains electrically isolated from each other for safety or reduces electromagnetic interference. Array of diodes made by standard integrated-circuit techniques and packaged for mounting at end of fiber-optic cable.

46 CFR 111.60-6 - Fiber optic cable.

Code of Federal Regulations, 2011 CFR

2011-10-01

... 46 Shipping 4 2011-10-01 2011-10-01 false Fiber optic cable. 111.60-6 Section 111.60-6 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-6 Fiber optic cable. Each fiber optic cable must— (a) Be...

46 CFR 111.60-6 - Fiber optic cable.

Code of Federal Regulations, 2014 CFR

2014-10-01

... 46 Shipping 4 2014-10-01 2014-10-01 false Fiber optic cable. 111.60-6 Section 111.60-6 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-6 Fiber optic cable. Each fiber optic cable must— (a) Be...

46 CFR 111.60-6 - Fiber optic cable.

Code of Federal Regulations, 2012 CFR

2012-10-01

... 46 Shipping 4 2012-10-01 2012-10-01 false Fiber optic cable. 111.60-6 Section 111.60-6 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-6 Fiber optic cable. Each fiber optic cable must— (a) Be...

46 CFR 111.60-6 - Fiber optic cable.

Code of Federal Regulations, 2013 CFR

2013-10-01

... 46 Shipping 4 2013-10-01 2013-10-01 false Fiber optic cable. 111.60-6 Section 111.60-6 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) ELECTRICAL ENGINEERING ELECTRIC SYSTEMS-GENERAL REQUIREMENTS Wiring Materials and Methods § 111.60-6 Fiber optic cable. Each fiber optic cable must— (a) Be...

Nanoelectronics enabled chronic multimodal neural platform in a mouse ischemic model.

PubMed

Luan, Lan; Sullender, Colin T; Li, Xue; Zhao, Zhengtuo; Zhu, Hanlin; Wei, Xiaoling; Xie, Chong; Dunn, Andrew K

2018-02-01

Despite significant advancements of optical imaging techniques for mapping hemodynamics in small animal models, it remains challenging to combine imaging with spatially resolved electrical recording of individual neurons especially for longitudinal studies. This is largely due to the strong invasiveness to the living brain from the penetrating electrodes and their limited compatibility with longitudinal imaging. We implant arrays of ultraflexible nanoelectronic threads (NETs) in mice for neural recording both at the brain surface and intracortically, which maintain great tissue compatibility chronically. By mounting a cranial window atop of the NET arrays that allows for chronic optical access, we establish a multimodal platform that combines spatially resolved electrical recording of neural activity and laser speckle contrast imaging (LSCI) of cerebral blood flow (CBF) for longitudinal studies. We induce peri-infarct depolarizations (PIDs) by targeted photothrombosis, and show the ability to detect its occurrence and propagation through spatiotemporal variations in both extracellular potentials and CBF. We also demonstrate chronic tracking of single-unit neural activity and CBF over days after photothrombosis, from which we observe reperfusion and increased firing rates. This multimodal platform enables simultaneous mapping of neural activity and hemodynamic parameters at the microscale for quantitative, longitudinal comparisons with minimal perturbation to the baseline neurophysiology. The ability to spatiotemporally resolve and chronically track CBF and neural electrical activity in the same living brain region has broad applications for studying the interplay between neural and hemodynamic responses in health and in cerebrovascular and neurological pathologies. Copyright © 2017 Elsevier B.V. All rights reserved.

Temperature dependent electrical properties of polyaniline film grown on paper through aniline vapor polymerization

NASA Astrophysics Data System (ADS)

Deb, K.; Bhowmik, K. L.; Bera, A.; Chattopadhyay, K. K.; Saha, B.

2016-05-01

Polyaniline thin film has been prepared on paper by aniline vapor deposition technique. Ferric chloride has been used as polymerizing agent in this approach. The prepared films were studied through electrical resistivity and optical properties measurements. The electrical resistivity of the polyaniline film shows significant temperature dependence. The resistance sharply falls with the increase in temperature. The optical absorbance measurements shows characteristics absorbance peak indicating the formation of conducting emeraldine salt form of polyaniline. The optical energy band gap of the film was calculated from the transmittance spectra. The optical energy band gap and electrical conductivity of the polyaniline film is well suited for their applications in electronic devices.

New strategy to promote conversion efficiency using high-index nanostructures in thin-film solar cells

PubMed Central

Wang, DongLin; Su, Gang

2014-01-01

Nano-scaled metallic or dielectric structures may provide various ways to trap light into thin-film solar cells for improving the conversion efficiency. In most schemes, the textured active layers are involved into light trapping structures that can provide perfect optical benefits but also bring undesirable degradation of electrical performance. Here we propose a novel approach to design high-performance thin-film solar cells. In our strategy, a flat active layer is adopted for avoiding electrical degradation, and an optimization algorithm is applied to seek for an optimized light trapping structure for the best optical benefit. As an example, we show that the efficiency of a flat a-Si:H thin-film solar cell can be promoted close to the certified highest value. It is also pointed out that, by choosing appropriate dielectric materials with high refractive index (>3) and high transmissivity in wavelength region of 350 nm–800 nm, the conversion efficiency of solar cells can be further enhanced. PMID:25418477

KSC-2013-3908

NASA Image and Video Library

2013-11-07

CAPE CANAVERAL, Fla. -- Dust particles scatter during an experiment for the Electrodynamic Dust Shield for Dust Mitigation project in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. The fabricated material is designed to mimic the dust on the lunar surface. The technology works by creating an electric field that propagates out like the ripples on a pond. This could prevent dust accumulation on spacesuits, thermal radiators, solar panels, optical instruments and view ports for future lunar and Mars exploration activities. CAPE CANAVERAL, Fla. -- Preparations are underway to conduct a dust particle experiment for the Electrodynamic Dust Shield for Dust Mitigation project in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. The technology works by creating an electric field that propagates out like the ripples on a pond. This could prevent dust accumulation on spacesuits, thermal radiators, solar panels, optical instruments and view ports for future lunar and Mars exploration activities.

KSC-2013-3907

NASA Image and Video Library

2013-11-07

CAPE CANAVERAL, Fla. -- Dust particles are readied for an experiment for the Electrodynamic Dust Shield for Dust Mitigation project in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. The fabricated material is designed to mimic the dust on the lunar surface. The technology works by creating an electric field that propagates out like the ripples on a pond. This could prevent dust accumulation on spacesuits, thermal radiators, solar panels, optical instruments and view ports for future lunar and Mars exploration activities. CAPE CANAVERAL, Fla. -- Preparations are underway to conduct a dust particle experiment for the Electrodynamic Dust Shield for Dust Mitigation project in the Electrostatics and Surface Physics Laboratory in the SwampWorks at NASA's Kennedy Space Center in Florida. The technology works by creating an electric field that propagates out like the ripples on a pond. This could prevent dust accumulation on spacesuits, thermal radiators, solar panels, optical instruments and view ports for future lunar and Mars exploration activities.

Demonstration of a high speed hybrid electrical and optical sensing system for next generation launcher applications

NASA Astrophysics Data System (ADS)

Ibrahim, Selwan K.; O'Dowd, John A.; Honniball, Arthur; Bessler, Vivian; Farnan, Martin; O'Connor, Peter; Melicher, Milos; Gleeson, Danny

2017-09-01

The Future Launchers Preparatory Programme (FLPP) supported by the European Space Agency (ESA) has a goal of developing various launch vehicle system concepts and identifying the technologies required for the design of Europe's Next-Generation Launcher (NGL) while maintaining competitiveness on the commercial market. Avionics fiber optic sensing technology was investigated as part of the FLPP programme. Here we demonstrate and evaluate a high speed hybrid electrical/optical data acquisition system based on commercial off the shelf (COTS) technology capable of acquiring data from traditional electrical sensors and optical Fibre Bragg Grating (FBG) sensors. The proposed system consists of the KAM-500 data acquisition system developed by Curtis-Wright and the I4 tunable laser based fiber optic sensor interrogator developed by FAZ Technology. The key objective was to demonstrate the capability of the hybrid system to acquire data from traditional electrical sensors used in launcher applications e.g. strain, temperature and pressure in combination with optical FBG sensors, as well as data delivery to spacecraft avionics systems. The KAM-500 was configured as the main acquisition unit (MAU) and provided a 1 kHz sampling clock to the I4 interrogator that was configured as the secondary acquisition unit (SAU) to synchronize the data acquisition sample rate between both systems. The SAU acquired data from an array of optical FBG sensors, while the MAU data acquisition system acquired data from the electrical sensors. Data acquired from the optical sensors was processed by the FAZ I4 interrogation system and then encapsulated into UDP/IP packets and transferred to the KAM-500. The KAM-500 encapsulated the optical sensor data together with the data acquired from electrical sensors and transmitted the data over MIL-STD-1553 and Ethernet data interface. The temperature measurements resulted in the optical and electrical sensors performing on a par with each other, with all sensors recording an accuracy within 0.35% FS over the full temperature range of -70°C to +180°C. The pressure measurements were performed over a 0 to 5 bar absolute pressure range and over different temperatures across a -40°C to +80°C range. The tests concluded that the optical pressure sensors performed on par with the electrical pressure sensor for each temperature set, where both sensor technologies measured a pressure accuracy of 1.2% FS. As for the strain measurements, the results show the optical and electrical sensors can measure to within 1% FS (Full Scale) of measurement range +/-1,200 μstrain. The proposed hybrid system can be potentially used for next generation launcher applications delivering weight reduction, improvement in measurement coverage and reduction in Assembly, Integration and Testing (AIT) over traditional electrical systems.

Ion Propulsion Thruster Including a Plurality of Ion Optic Electrode Pairs

NASA Technical Reports Server (NTRS)

Patterson, Michael J. (Inventor)

2016-01-01

Ion optics for use in a conventional or annular or other shaped ion thruster are disclosed including a plurality of planar, spaced apart ion optic electrode pairs sized to include a diameter smaller than the diameter of thruster exhaust and retained in, on or otherwise associated with a frame across the thruster exhaust. An electrical connection may be provided for establishing electrical connectivity among a set of first upstream electrodes and an electrical connection may be provided for establishing electrical connectivity among the second downstream electrodes.

Vehicle security apparatus and method

DOEpatents

Veligdan, J.T.

1996-02-13

A vehicle security apparatus for use in a motor vehicle is disclosed, the apparatus comprising an optical key, a receptacle, a receiver and at least one optical fiber. The optical key has a transmitter having at least one first preprogrammed coded signal stored in a first electric circuit. The receptacle receives the optical key and at least one transmittable coded optical signal from the transmitter corresponding to the at least one preprogrammed coded signal stored in the first electric circuit. The receiver compares the at least one transmittable coded optical signal to at least one second preprogrammed coded signal stored in a second electric circuit and the receiver is adapted to trigger switching effects for at least one of enabling starting the motor vehicle and starting the motor vehicle upon determination that the at least one transmittable coded optical signal corresponds to the at least one second preprogrammed signal in the second electric circuit. The at least one optical fiber is operatively connected between the receptacle and the receiver for carrying the optical signal from the receptacle to the receiver. Also disclosed is a method for permitting only authorized use of a motor vehicle. 7 figs.

Imaging electric field dynamics with graphene optoelectronics.

PubMed

Horng, Jason; Balch, Halleh B; McGuire, Allister F; Tsai, Hsin-Zon; Forrester, Patrick R; Crommie, Michael F; Cui, Bianxiao; Wang, Feng

2016-12-16

The use of electric fields for signalling and control in liquids is widespread, spanning bioelectric activity in cells to electrical manipulation of microstructures in lab-on-a-chip devices. However, an appropriate tool to resolve the spatio-temporal distribution of electric fields over a large dynamic range has yet to be developed. Here we present a label-free method to image local electric fields in real time and under ambient conditions. Our technique combines the unique gate-variable optical transitions of graphene with a critically coupled planar waveguide platform that enables highly sensitive detection of local electric fields with a voltage sensitivity of a few microvolts, a spatial resolution of tens of micrometres and a frequency response over tens of kilohertz. Our imaging platform enables parallel detection of electric fields over a large field of view and can be tailored to broad applications spanning lab-on-a-chip device engineering to analysis of bioelectric phenomena.

Optical pulling and pushing forces exerted on silicon nanospheres with strong coherent interaction between electric and magnetic resonances.

PubMed

Liu, Hongfeng; Panmai, Mingcheng; Peng, Yuanyuan; Lan, Sheng

2017-05-29

We investigated theoretically and numerically the optical pulling and pushing forces acting on silicon (Si) nanospheres (NSs) with strong coherent interaction between electric and magnetic resonances. We examined the optical pulling and pushing forces exerted on Si NSs by two interfering waves and revealed the underlying physical mechanism from the viewpoint of electric- and magnetic-dipole manipulation. As compared with a polystyrene (PS) NS, it was found that the optical pulling force for a Si NS with the same size is enlarged by nearly two orders of magnitude. In addition to the optical pulling force appearing at the long-wavelength side of the magnetic dipole resonance, very large optical pushing force is observed at the magnetic quadrupole resonance. The correlation between the optical pulling/pushing force and the directional scattering characterized by the ratio of the forward to backward scattering was revealed. More interestingly, it was found that the high-order electric and magnetic resonances in large Si NSs play an important role in producing optical pulling force which can be generated by not only s-polarized wave but also p-polarized one. Our finding indicates that the strong coherent interaction between the electric and magnetic resonances existing in nanoparticles with large refractive indices can be exploited to manipulate the optical force acting on them and the correlation between the optical force and the directional scattering can be used as guidance. The engineering and manipulation of optical forces will find potential applications in the trapping, transport and sorting of nanoparticles.

Retinal projections in the electric catfish (Malapterurus electricus).

PubMed

Ebbesson, S O; O'Donnel, D

1980-01-01

The poorly developed visual system of the electric catfish was studied with silver-degeneration methods. Retinal projections were entirely contralateral to the hypothalamic optic nucleus, the lateral geniculate nucleus, the dorsomedial optic nucleus, the pretectal nuclei including the cortical nucleus, and the optic tectum. The small size and lack of differentiation of the visual system in the electric catfish suggest a relatively small role for this sensory system in this species.

Synthesis, growth, spectral, electrical, mechanical and thermal characterization of a potential optical material: γ-glycine single crystal

NASA Astrophysics Data System (ADS)

Sivakumar, N.; Jayavel, R.; Anbalagan, G.; Yadav, R. R.

2018-06-01

Gamma glycine, an organic material was grown by slow solvent evaporation method. Conventional polythermal method was employed in the temperature range, 30-50 °C to obtain the solubility and the metastable zonewidth. The crystal and molecular structures were analyzed by X-ray powder diffraction, FT-IR and FT-Raman spectral studies. Optical refractive index was determined by prism coupling technique and was found to be 1.4488. Electrical properties such as ac conductivity and activation energy were studied for different temperatures in the frequency range from 40 Hz to 6 MHz. The dc electrical conductivity was estimated from the Cole-Cole plot and the values were found to be 2.19 × 10-6 Sm-1 at 353K and 1.46 × 10-6 Sm-1 at 373K respectively. Mechanical studies on the grown crystal revealed that the material belongs to soft materials category. Thermal conductivity and specific heat capacities were estimated by Hot Disk Thermal Constants Analyzer.

Heterogeneous 3D optrode with variable spatial resolution for optogenetic stimulation and electrophysiological recording.

PubMed

Ayub, Suleman; Barz, Falk; Paul, Oliver; Ruther, Patrick

2016-08-01

We report on the concept, development, and geometrical, optical as well as electrical characterization of the first three-dimensional (3D) optrode. This new device allows to optically interact with neuronal cells and simultaneously record their response with a high spatial resolution. Our design is based on a single-shank optical stimulation component and a multi-shank recording probe stacked together in a delicate assembly process. The electrical connection of both components is ensured by using flexible polyimide (PI) ribbon cables. The highly accurate relative positioning and precise alignment of the optical and electrical components in 3D with an optical output power at 460 nm well above 5 mW/mm2 and an all-electrical interface makes this device a promising tool for optogenetic experiments in neuroscientific research.

Nanoimprinting-induced nanomorphological transition in polymer solar cells: enhanced electrical and optical performance.

PubMed

Jeong, Seonju; Cho, Changsoon; Kang, Hyunbum; Kim, Ki-Hyun; Yuk, Youngji; Park, Jeong Young; Kim, Bumjoon J; Lee, Jung-Yong

2015-03-24

We have investigated the effects of a directly nanopatterned active layer on the electrical and optical properties of inverted polymer solar cells (i-PSCs). The capillary force in confined molds plays a critical role in polymer crystallization and phase separation of the film. The nanoimprinting process induced improved crystallization and multidimensional chain alignment of polymers for more effective charge transfer and a fine phase-separation between polymers and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) to favor exciton dissociation and increase the generation rate of charge transfer excitons. Consequently, the power conversion efficiency with a periodic nanostructure was enhanced from 7.40% to 8.50% and 7.17% to 9.15% in PTB7 and PTB7-Th based i-PSCs, respectively.

Optical fibre sensing: a solution for industry

NASA Astrophysics Data System (ADS)

Sun, T.; Fabian, M.; Chen, Y.; Vidakovic, M.; Javdani, S.; Grattan, K. T. V.; Carlton, J.; Gerada, C.; Brun, L.

2017-04-01

Optical fibres have been explored widely for their sensing capability to meet increasing industrial needs, building on their success in telecommunications. This paper provides a review of research activities at City University of London in response to industrial challenges through the development of a range of fibre Bragg grating (FBG)-based sensors for transportation structural monitoring. For marine propellers, arrays of FBGs mapped onto the surface of propeller blades allow for capturing vibrational modes, with reference to simulation data. The research funded by EU Cleansky programme enables the development of self-sensing electric motor drives to support `More Electric Aircraft' concept. The partnership with Faiveley Brecknell Willis in the UK enables the integration of FBG sensors into the railway current-collecting pantographs for real-time condition monitoring when they are operating under 25kV conditions.

High Photoelectric Conversion Efficiency of Metal Phthalocyanine/Fullerene Heterojunction Photovoltaic Device

PubMed Central

Lin, Chi-Feng; Zhang, Mi; Liu, Shun-Wei; Chiu, Tien-Lung; Lee, Jiun-Haw

2011-01-01

This paper introduces the fundamental physical characteristics of organic photovoltaic (OPV) devices. Photoelectric conversion efficiency is crucial to the evaluation of quality in OPV devices, and enhancing efficiency has been spurring on researchers to seek alternatives to this problem. In this paper, we focus on organic photovoltaic (OPV) devices and review several approaches to enhance the energy conversion efficiency of small molecular heterojunction OPV devices based on an optimal metal-phthalocyanine/fullerene (C60) planar heterojunction thin film structure. For the sake of discussion, these mechanisms have been divided into electrical and optical sections: (1) Electrical: Modification on electrodes or active regions to benefit carrier injection, charge transport and exciton dissociation; (2) Optical: Optional architectures or infilling to promote photon confinement and enhance absorption. PMID:21339999

Ionic and Optical Properties of Methylammonium Lead Iodide Perovskite across the Tetragonal-Cubic Structural Phase Transition

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoque, Md Nadim Ferdous; Islam, Nazifah; Li, Zhen

Practical hybrid perovskite solar cells (PSCs) must endure temperatures above the tetragonal-cubic structural phase transition of methylammonium lead iodide (MAPbI3). However, the ionic and optical properties of MAPbI3 in such a temperature range, and particularly, dramatic changes in these properties resulting from a structural phase transition, are not well studied. Herein, we report a striking contrast at approximately 45 degrees C in the ionic/electrical properties of MAPbl3 owing to a change of the ion activation energy from 0.7 to 0.5 eV, whereas the optical properties exhibit no particular transition except for the steady increase of the bandgap with temperature. Thesemore » observations can be explained by the 'continuous' nature of perovskite phase transition. We speculate that the critical temperature at which the ionic/electrical properties change, although related to crystal symmetry variation, is not necessarily the same temperature as when tetragonal-cubic structural phase transition occurs.« less

High Sensitivity Stress Sensor Based on Hybrid Materials

NASA Technical Reports Server (NTRS)

Cao, Xian-An (Inventor)

2014-01-01

A sensing device is used to detect the spatial distributions of stresses applied by physical contact with the surface of the sensor or induced by pressure, temperature gradients, and surface absorption. The sensor comprises a hybrid active layer that includes luminophores doped in a polymeric or organic host, altogether embedded in a matrix. Under an electrical bias, the sensor simultaneously converts stresses into electrical and optical signals. Among many applications, the device may be used for tactile sensing and biometric imaging.

Processes for design, construction and utilisation of arrays of light-emitting diodes and light-emitting diode-coupled optical fibres for multi-site brain light delivery

PubMed Central

Bernstein, Jacob G.; Allen, Brian D.; Guerra, Alexander A.; Boyden, Edward S.

2016-01-01

Optogenetics enables light to be used to control the activity of genetically targeted cells in the living brain. Optical fibers can be used to deliver light to deep targets, and LEDs can be spatially arranged to enable patterned light delivery. In combination, arrays of LED-coupled optical fibers can enable patterned light delivery to deep targets in the brain. Here we describe the process flow for making LED arrays and LED-coupled optical fiber arrays, explaining key optical, electrical, thermal, and mechanical design principles to enable the manufacturing, assembly, and testing of such multi-site targetable optical devices. We also explore accessory strategies such as surgical automation approaches as well as innovations to enable low-noise concurrent electrophysiology. PMID:26798482

All Optical Solution for Free Space Optics Point to Point Links

NASA Astrophysics Data System (ADS)

Hirayama, Daigo

Optical network systems are quickly replacing electrical network systems. Optical systems provide better bandwidth, faster data rates, better security to networks, and are less susceptible to noise. Free Space Optics (systems) still rely on numerous electrical systems such as the modulation and demodulation systems to convert optical signals to electrical signals for the transmitting laser. As the concept of the entirely optical network becomes more realizable, the electrical components of the FSO system will become a hindrance to communications. The focus of this thesis is to eliminate the electrical devices for the FSO point to point links by replacing them with optical devices. The concept is similar to an extended beam connector. However, where an extended beam connector deals with a gap of a few millimeters, my focus looks at distances from 100 meters to one kilometer. The aim is to achieve a detectable signal of 1nW at a distance of 500 meters at a wavelength of 1500-1600nm. This leads to application in building to building links and mobile networks. The research examines the design of the system in terms of generating the wave, the properties of the fiber feeding the wave, and the power necessary to achieve a usable distance. The simulation is executed in Code V by Synopsys, which is an industry standard to analyze optical systems. A usable device with a range of around 500m was achieved with an input power of 1mW. The approximations of the phase function resulted in some aberrations to the profile of the beam, but were not very detrimental to the function of the device. The removal of electrical devices from a FSO point to point link decreased the power used to establish the link and decreased the cost.

Studies of Phase-Conjugate Optical Device Concepts

DTIC Science & Technology

1991-04-01

09/30/90 1991, APRIL 127 I&. SUPPLEMENTARY NOTAT11ON 17. COSATI CODES 18. SUBJECT TERMS fCondnue on~e ow twmInocemy and Iknffyby block numbw) FIELD ...coherent; beams 3 and 4 are also mutually gratings are identical, i.e., coherent. But beams 2 and 3 (or 2 and 4) are mutually incoherent. The electric field ...Introduction Science Center Optical phase conjugation has been an active field of research for nearly two decades. 1 One of the more unusual additions to the

Jammed-array wideband sawtooth filter.

PubMed

Tan, Zhongwei; Wang, Chao; Goda, Keisuke; Malik, Omer; Jalali, Bahram

2011-11-21

We present an all-optical passive low-cost spectral filter that exhibits a high-resolution periodic sawtooth spectral pattern without the need for active optoelectronic components. The principle of the filter is the partial masking of a phased array of virtual light sources with multiply jammed diffraction orders. We utilize the filter's periodic linear map between frequency and intensity to demonstrate fast sensitive interrogation of fiber Bragg grating sensor arrays and ultrahigh-frequency electrical sawtooth waveform generation. © 2011 Optical Society of America

Electronically tuned optical filters

NASA Technical Reports Server (NTRS)

Castellano, J. A.; Pasierb, E. F.; Oh, C. S.; Mccaffrey, M. T.

1972-01-01

A detailed account is given of efforts to develop a three layer, polychromic filter that can be tuned electronically. The operation of the filter is based on the cooperative alignment of pleochroic dye molecules by nematic liquid crystals activated by electric fields. This orientation produces changes in the optical density of the material and thus changes in the color of light transmitted through the medium. In addition, attempts to improve materials and devices which employ field induced changes of a cholesteric to a nematic liquid crystal are presented.

Dielectric waveguide gas-filled stark shift modulator

DOEpatents

Hutchinson, Donald P.; Richards, Roger K.

2003-07-22

An optical modulator includes a dielectric waveguide for receiving an optical beam and coupling energy of the optical beam into the waveguide. At least one Stark material is provided in the waveguide. A bias circuit generates a bias signal to produce an electrical field across the Stark material to shift at least one of the Stark absorption frequencies towards the frequency of the optical beam. A circuit for producing a time varying electric field across the Stark material modulates the optical beam. At least a portion of the bias field can be generated by an alternating bias signal, such as a square wave. A method of modulating optical signals includes the steps of providing a dielectric waveguide for receiving an optical beam and coupling energy of the optical beam into the waveguide, the waveguide having at least one Stark material disposed therein, and varying an electric field imposed across the Stark material.

Compact electro-optical module with polymer waveguides on a flexible substrate for high-density board-level communication

NASA Astrophysics Data System (ADS)

Weiss, J. R. M.; Lamprecht, T.; Meier, N.; Dangel, R.; Horst, F.; Jubin, D.; Beyeler, R.; Offrein, B. J.

2010-02-01

We report on the co-packaging of electrical CMOS transceiver and VCSEL chip arrays on a flexible electrical substrate with optical polymer waveguides. The electro-optical components are attached to the substrate edge and butt-coupled to the waveguides. Electrically conductive silver-ink connects them to the substrate at an angle of 90°. The final assembly contacts the surface of a package laminate with an integrated compressible connector. The module can be folded to save space, requires only a small footprint on the package laminate and provides short electrical high-speed signal paths. With our approach, the electro-optical package becomes a compact electro-optical module with integrated polymer waveguides terminated with either optical connectors (e.g., at the card edge) or with an identical assembly for a second processor on the board. Consequently, no costly subassemblies and connectors are needed, and a very high integration density and scalability to virtually arbitrary channel counts and towards very high data rates (20+ Gbps) become possible. Future cost targets of much less than US$1 per Gbps will be reached by employing standard PCB materials and technologies that are well established in the industry. Moreover, our technology platform has both electrical and optical connectivity and functionality.

Optical mapping system with real-time control capability.

PubMed

Iravanian, Shahriar; Christini, David J

2007-10-01

Real-time, closed-loop intervention is an emerging experiment-control method that promises to provide invaluable new insight into cardiac electrophysiology. One example is the investigation of closed-loop feedback control of cardiac activity (e.g., alternans) as a possible method of preventing arrhythmia onset. To date, such methods have been investigated only in vitro using microelectrode systems, which are hindered by poor spatial resolution and are not well suited for atrial or ventricular tissue preparations. We have developed a system that uses optical mapping techniques and an electrical stimulator as the sensory and effector arms, respectively, of a closed-loop, real-time control system. The system consists of a 2,048 x 1 pixel line-scan charge-coupled device camera that records optical signals from the tissue. Custom-image processing and control software, which is implemented on top of a hard real-time operation system (RTAI Linux), process the data and make control decisions with a deterministic delay of <1 ms. The system is tested in two ways: 1) it is used to control, in real time, simulated optical signals of electrical alternans; and 2) it uses precisely timed, feedback-controlled initiation of antitachycardia pacing to terminate reentrant arrhythmias in an arterially perfused swine right ventricle stained with voltage-sensitive fluorescent dye 4{beta-[2-(di-n-butylamino)-6-napathy]vinyl}pyridinium (di-4-ANEPPS). Thus real-time control of cardiac activity using optical mapping techniques is feasible. Such a system is attractive because it offers greater measurement resolution than the electrode-based systems with which real-time control has been used previously.

Single-Mode, Distributed Feedback Interband Cascade Lasers

NASA Technical Reports Server (NTRS)

Frez, Clifford F. (Inventor); Borgentun, Carl E. (Inventor); Briggs, Ryan M. (Inventor); Bagheri, Mahmood (Inventor); Forouhar, Siamak (Inventor)

2016-01-01

Single-mode, distributed feedback interband cascade lasers (ICLs) using distributed-feedback gratings (e.g., lateral Bragg gratings) and methods of fabricating such ICLs are provided. The ICLs incorporate distributed-feedback gratings that are formed above the laser active region and adjacent the ridge waveguide (RWG) of the ICL. The ICLs may incorporate a double-ridge system comprising an optical confinement structure (e.g., a RWG) disposed above the laser active region that comprises the first ridge of the double ridge system, a DFB grating (e.g., lateral Bragg grating) disposed above the laser active region and adjacent the optical confinement structure, and an electric confinement structure that passes at least partially through the laser active region and that defines the boundary of the second ridge comprises and the termination of the DFB grating.

Effect of rapid thermal annealing on the electrical, optical and structural properties of ZnO-doped In2O3 films grown by linear facing target sputtering.

PubMed

Cho, Chung-Ki; Kim, Han-Ki

2012-04-01

We investigated the effect of rapid thermal annealing on the electrical, optical, and structural properties of ZnO-doped In2O3 (ZIO) films grown at different Ar/O2 flow ratios (15/0 and 15/1 sccm) by using linear facing target sputtering. It was found that the ZIO films grown at different Ar/O2, flow ratios showed different electrical and optical behavior with increasing rapid thermal annealing temperature. Synchrotron X-ray scattering examination showed that the different electrical and optical properties of the ZIO films could be attributed to the difference in preferred orientation with an increase in rapid thermal annealing temperature.

Temperature dependent electrical properties of polyaniline film grown on paper through aniline vapor polymerization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Deb, K.; Bera, A.; Saha, B., E-mail: biswajit.physics@gmail.com

2016-05-23

Polyaniline thin film has been prepared on paper by aniline vapor deposition technique. Ferric chloride has been used as polymerizing agent in this approach. The prepared films were studied through electrical resistivity and optical properties measurements. The electrical resistivity of the polyaniline film shows significant temperature dependence. The resistance sharply falls with the increase in temperature. The optical absorbance measurements shows characteristics absorbance peak indicating the formation of conducting emeraldine salt form of polyaniline. The optical energy band gap of the film was calculated from the transmittance spectra. The optical energy band gap and electrical conductivity of the polyaniline filmmore » is well suited for their applications in electronic devices.« less

Manipulation of local optical properties and structures in molybdenum-disulfide monolayers using electric field-assisted near-field techniques.

PubMed

Nozaki, Junji; Fukumura, Musashi; Aoki, Takaaki; Maniwa, Yutaka; Yomogida, Yohei; Yanagi, Kazuhiro

2017-04-05

Remarkable optical properties, such as quantum light emission and large optical nonlinearity, have been observed in peculiar local sites of transition metal dichalcogenide monolayers, and the ability to tune such properties is of great importance for their optoelectronic applications. For that purpose, it is crucial to elucidate and tune their local optical properties simultaneously. Here, we develop an electric field-assisted near-field technique. Using this technique we can clarify and tune the local optical properties simultaneously with a spatial resolution of approximately 100 nm due to the electric field from the cantilever. The photoluminescence at local sites in molybdenum-disulfide (MoS 2 ) monolayers is reversibly modulated, and the inhomogeneity of the charge neutral points and quantum yields is suggested. We successfully etch MoS 2 crystals and fabricate nanoribbons using near-field techniques in combination with an electric field. This study creates a way to tune the local optical properties and to freely design the structural shapes of atomic monolayers using near-field optics.

Performance improvement of optical fiber coupler with electric heating versus gas heating.

PubMed

Shuai, Cijun; Gao, Chengde; Nie, Yi; Peng, Shuping

2010-08-20

Gas heating has been widely used in the process of fused biconical tapering. However, as the instability and asymmetric flame temperature of gas heating exist, the performance of the optical devices fabricated by this method was affected. To overcome the problems resulting from gas combustion, an electric heater is designed and manufactured using a metal-ceramic (MoSi(2)) as a heating material. Our experimental data show that the fused-taper machine with an electric heater has improved the performance of optical devices by increasing the consistency of the extinction ratio, excess loss, and the splitting ratio over that of the previous gas heating mode. Microcrystallizations and microcracks were observed at the fused region of the polarization-maintaining (PM) fiber coupler and at the taper region with scanning electron microscopy and atomic force microscopy respectively. The distribution of the microcrystallizations and microcracks are nonuniform along the fiber with gas heating, while their distribution is rather uniform with electric heating. These findings show that the novel optical fiber coupler with an electric heater has improved the performance of optical fiber devices by affecting the consistency of the optical parameters and micromorphology of the surface of PM fiber.

Pulse shaping system

DOEpatents

Skeldon, Mark D.; Letzring, Samuel A.

1999-03-23

Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses.

Pulse shaping system

DOEpatents

Skeldon, M.D.; Letzring, S.A.

1999-03-23

Temporally shaped electrical waveform generation provides electrical waveforms suitable for driving an electro-optic modulator (EOM) which produces temporally shaped optical laser pulses for inertial confinement fusion (ICF) research. The temporally shaped electrical waveform generation is carried out with aperture coupled transmission lines having an input transmission line and an aperture coupled output transmission line, along which input and output pulses propagate in opposite directions. The output electrical waveforms are shaped principally due to the selection of coupling aperture width, in a direction transverse to the lines, which varies along the length of the line. Specific electrical waveforms, which may be high voltage (up to kilovolt range), are produced and applied to the EOM to produce specifically shaped optical laser pulses. 8 figs.

Improvement in the electrical performance and bias-stress stability of dual-active-layered silicon zinc oxide/zinc oxide thin-film transistor

NASA Astrophysics Data System (ADS)

Liu, Yu-Rong; Zhao, Gao-Wei; Lai, Pai-To; Yao, Ruo-He

2016-08-01

Si-doped zinc oxide (SZO) thin films are deposited by using a co-sputtering method, and used as the channel active layers of ZnO-based TFTs with single and dual active layer structures. The effects of silicon content on the optical transmittance of the SZO thin film and electrical properties of the SZO TFT are investigated. Moreover, the electrical performances and bias-stress stabilities of the single- and dual-active-layer TFTs are investigated and compared to reveal the effects of the Si doping and dual-active-layer structure. The average transmittances of all the SZO films are about 90% in the visible light region of 400 nm-800 nm, and the optical band gap of the SZO film gradually increases with increasing Si content. The Si-doping can effectively suppress the grain growth of ZnO, revealed by atomic force microscope analysis. Compared with that of the undoped ZnO TFT, the off-state current of the SZO TFT is reduced by more than two orders of magnitude and it is 1.5 × 10-12 A, and thus the on/off current ratio is increased by more than two orders of magnitude. In summary, the SZO/ZnO TFT with dual-active-layer structure exhibits a high on/off current ratio of 4.0 × 106 and superior stability under gate-bias and drain-bias stress. Projected supported by the National Natural Science Foundation of China (Grant Nos. 61076113 and 61274085), the Natural Science Foundation of Guangdong Province (Grant No. 2016A030313474), and the University Development Fund (Nanotechnology Research Institute, Grant No. 00600009) of the University of Hong Kong, China.

Introduction of a new opto-electrical phase-locked loop in CMOS technology: the PMD-PLL

NASA Astrophysics Data System (ADS)

Ringbeck, Thorsten; Schwarte, Rudolf; Buxbaum, Bernd

1999-12-01

The huge and increasing need of information in the industrial world demands an enormous potential of bandwidth in telecommunication systems. Optical communication provides all participants with the whole spectrum of digital services like videophone, cable TV, video conferencing and online services. Especially fast and low cost opto-electrical receivers are badly needed in order to expand fiber networks to every home (FTTH--fiber to the home or FTTD--fiber to the desk, respectively). This paper proposes a new receiver structure which is designed to receiver optical data which are encoded by code division multiple access techniques (CDMA). For data recovery in such CDMA networks phase locked loops (PLL) are needed, which synchronize the local oscillator with the incoming clock. In optical code division multiple access networks these PLLs could be realized either with an electrical PLL after opto-electrical converting or directly in the optical path with a pure optical PLL.

An optical system adopting liquid crystals with electrical tunability of wavelength and energy density for low level light therapy

NASA Astrophysics Data System (ADS)

Chang, Chia-Ming; Wang, Yu-Jen; Chen, Hung-Shan; Lin, Yi-Hsin; Srivastava, Abhishek K.; Chigrinov, Vladimir G.

2015-09-01

We have developed a bistable negative lens by integrating a polarization switch of ferroelectric liquid crystals (FLCs) with a passively anisotropic focusing element. The proposed lens not only exhibits electrically tunable bistability but also fast response time of sub-milliseconds, which leads to good candidate of optical component in optical system for medical applications. In this paper, we demonstrate an optical system consisting of two FLC phase retarders and one LC lenses that exhibits both of electrically tunable wavelength and size of exposure area. The operating principles and the experimental results are discussed. The tunable spectrum, exposure area size and tunable irradiance are illustrated. Compared to conventional lenses with mechanical movements in the medical light therapy system, our electrically switchable optical system is more practical in the portable applications of light therapy (LLLT).

Comprehensive photonics-electronics convergent simulation and its application to high-speed electronic circuit integration on a Si/Ge photonic chip

NASA Astrophysics Data System (ADS)

Takeda, Kotaro; Honda, Kentaro; Takeya, Tsutomu; Okazaki, Kota; Hiraki, Tatsurou; Tsuchizawa, Tai; Nishi, Hidetaka; Kou, Rai; Fukuda, Hiroshi; Usui, Mitsuo; Nosaka, Hideyuki; Yamamoto, Tsuyoshi; Yamada, Koji

2015-01-01

We developed a design technique for a photonics-electronics convergence system by using an equivalent circuit of optical devices in an electrical circuit simulator. We used the transfer matrix method to calculate the response of an optical device. This method used physical parameters and dimensions of optical devices as calculation parameters to design a device in the electrical circuit simulator. It also used an intermediate frequency to express the wavelength dependence of optical devices. By using both techniques, we simulated bit error rates and eye diagrams of optical and electrical integrated circuits and calculated influences of device structure change and wavelength shift penalty.

Covert laser remote sensing and vibrometry

NASA Technical Reports Server (NTRS)

Maleki, Lutfollah (Inventor); Yu, Nan (Inventor); Matsko, Andrey B. (Inventor); Savchenkov, Anatoliy (Inventor)

2012-01-01

Designs of single-beam laser vibrometry systems and methods. For example, a method for detecting vibrations of a target based on optical sensing is provided to include operating a laser to produce a laser probe beam at a laser frequency and modulated at a modulation frequency onto a target; collecting light at or near the laser to collect light from the target while the target is being illuminated by the laser probe beam through an optical receiver aperture; using a narrow-band optical filter centered at the laser frequency to filter light collected from the optical receiver aperture to transmit light at the laser frequency while blocking light at other frequencies; using an optical detector to convert filtered light from the narrow-band optical filter to produce a receiver electrical signal; using a lock-in amplifier to detect and amplify the receiver electrical signal at the modulation frequency while rejecting signal components at other frequencies to produce an amplified receiver electrical signal; processing the amplified receiver electrical signal to extract information on vibrations of the target carried by reflected laser probe beam in the collected light; and controlling optical power of the laser probe beam at the target to follow optical power of background illumination at the target.

Simultaneous EEG and diffuse optical imaging of seizure-related hemodynamic activity in the newborn infant brain

NASA Astrophysics Data System (ADS)

Hebden, Jeremy C.; Cooper, Robert J.; Gibson, Adam; Everdell, Nick; Austin, Topun

2012-06-01

An optical imaging system has been developed which uses measurements of diffusely reflected near-infrared light to produce maps of changes in blood flow and oxygenation occurring within the cerebral cortex. Optical sources and detectors are coupled to the head via an array of optical fibers, on a probe held in contact with the scalp, and data is collected at a rate of 10 Hz. A clinical electroencephalography (EEG) system has been integrated with the optical system to enable simultaneous observation of electrical and hemodynamic activity in the cortex of neurologically compromised newborn infants diagnosed with seizures. Studies have made a potentially critically important discovery of previously unknown transient hemodynamic events in infants treated with anticonvulsant medication. We observed repeated episodes of small increases in cortical oxyhemoglobin concentration followed by a profound decrease in 3 of 4 infants studied, each with cerebral injury who presented with neonatal seizures. This was not accompanied by clinical or EEG seizure activity and was not present in nineteen matched controls. The underlying cause of these changes is currently unknown. We tentatively suggest that our results may be associated with a phenomenon known as cortical spreading depolarization, not previously observed in the infant brain.

Simultaneous remote measurement of CO2 concentration, humidity and temperature with a matrix of optical fiber sensors

NASA Astrophysics Data System (ADS)

Wysokiński, Karol; Filipowicz, Marta; Stańczyk, Tomasz; Lipiński, Stanisław; Napierała, Marek; Murawski, Michał; Nasiłowski, Tomasz

2017-10-01

A matrix of optical fiber sensors eligible for remote measurements is reported in this paper. The aim of work was to monitor the air quality with a device, which does not need any electricity on site of the measurement. The matrix consists of several sensors detecting carbon dioxide concentration, relative humidity and temperature. Sensors utilize active optical materials, which change their color when exposed to varied conditions. All the sensors are powered with standard light emitting diodes. Light is transmitted by an optical fiber from the light source and then it reaches the active layer which changes its color, when the conditions change. This results in a change of attenuation of light passing through the active layer. Modified light is then transmitted by another optical fiber to the detector, where simple photoresistor is used. It is powered by a stabilized DC power supply and the current is measured. Since no expensive elements are needed to manufacture such a matrix of sensors, its price may be competitive to the price of the devices already available on the market, while the matrix also exhibits other valuable properties.

Tunable terahertz optical properties of graphene in dc electric fields

NASA Astrophysics Data System (ADS)

Dong, H. M.; Huang, F.; Xu, W.

2018-03-01

We develop a simple theoretical approach to investigate terahertz (THz) optical properties of monolayer graphene in the presence of an external dc electric field. The analytical results for optical coefficients such as the absorptance and reflectivity are obtained self-consistently on the basis of a diagrammatic self-consistent field theory and a Boltzmann equilibrium equation. It is found that the optical refractive index, reflectivity and conductivity can be effectively tuned by not only a gate voltage but also a driving dc electric field. This study is relevant to the applications of graphene as advanced THz optoelectronic devices.

Intrinsic optical signal imaging of glucose-stimulated physiological responses in the insulin secreting INS-1 β-cell line

NASA Astrophysics Data System (ADS)

Li, Yi-Chao; Cui, Wan-Xing; Wang, Xu-Jing; Amthor, Franklin; Yao, Xin-Cheng

2011-03-01

Intrinsic optical signal (IOS) imaging has been established for noninvasive monitoring of stimulus-evoked physiological responses in the retina and other neural tissues. Recently, we extended the IOS imaging technology for functional evaluation of insulin secreting INS-1 cells. INS-1 cells provide a popular model for investigating β-cell dysfunction and diabetes. Our experiments indicate that IOS imaging allows simultaneous monitoring of glucose-stimulated physiological responses in multiple cells with high spatial (sub-cellular) and temporal (sub-second) resolution. Rapid image sequences reveal transient optical responses that have time courses comparable to glucose-evoked β-cell electrical activities.

Photonic band gap materials: towards an all-optical transistor

NASA Astrophysics Data System (ADS)

Florescu, Marian

2002-05-01

The transmission of information as optical signals encoded on light waves traveling through optical fibers and optical networks is increasingly moving to shorter and shorter distance scales. In the near future, optical networking is poised to supersede conventional transmission over electric wires and electronic networks for computer-to-computer communications, chip-to-chip communications, and even on-chip communications. The ever-increasing demand for faster and more reliable devices to process the optical signals offers new opportunities in developing all-optical signal processing systems (systems in which one optical signal controls another, thereby adding "intelligence" to the optical networks). All-optical switches, two-state and many-state all-optical memories, all-optical limiters, all-optical discriminators and all-optical transistors are only a few of the many devices proposed during the last two decades. The "all-optical" label is commonly used to distinguish the devices that do not involve dissipative electronic transport and require essentially no electrical communication of information. The all-optical transistor action was first observed in the context of optical bistability [1] and consists in a strong differential gain regime, in which, for small variations in the input intensity, the output intensity has a very strong variation. This analog operation is for all-optical input what transistor action is for electrical inputs.

Fabrication and electrical characterization of silicon nanowires based resistors

NASA Astrophysics Data System (ADS)

Ni, L.; Demami, F.; Rogel, R.; Salaün, A. C.; Pichon, L.

2009-11-01

Silicon nanowires (SiNWs) are synthesized via the Vapor-Liquid-Solid (VLS) mechanism using gold (Au) as metal catalyst and silane (SiH4) as precursor gas. Au nanoparticles are employed as liquid droplets catalysis during the SiNWs growth performed in a hot wall LPCVD reactor at 480°C and 40 Pa. SiNWs local synthesis at micron scale is demonstrated using classical optical photolithography process. SiNWs grow with high density anchored at the dedicated catalyst islands. This resulting network is used to interconnect two heavily doped polysilicon interdigitated electrodes leading to the formation of electrical resistors in a coplanar structure. Current-voltage (I-V) characteristics highlight a symmetric shape. The temperature dependence of the electrical resistance is activated, with activation energy of 0.47 eV at temperatures greater than 300K.

Electrically-pumped compact hybrid silicon microring lasers for optical interconnects.

PubMed

Liang, Di; Fiorentino, Marco; Okumura, Tadashi; Chang, Hsu-Hao; Spencer, Daryl T; Kuo, Ying-Hao; Fang, Alexander W; Dai, Daoxin; Beausoleil, Raymond G; Bowers, John E

2009-10-26

We demonstrate an electrically-pumped hybrid silicon microring laser fabricated by a self-aligned process. The compact structure (D = 50 microm) and small electrical and optical losses result in lasing threshold as low as 5.4 mA and up to 65 degrees C operation temperature in continuous-wave (cw) mode. The spectrum is single mode with large extinction ratio and small linewidth observed. Application as on-chip optical interconnects is discussed from a system perspective.

Vector optical fields with polarization distributions similar to electric and magnetic field lines.

PubMed

Pan, Yue; Li, Si-Min; Mao, Lei; Kong, Ling-Jun; Li, Yongnan; Tu, Chenghou; Wang, Pei; Wang, Hui-Tian

2013-07-01

We present, design and generate a new kind of vector optical fields with linear polarization distributions modeling to electric and magnetic field lines. The geometric configurations of "electric charges" and "magnetic charges" can engineer the spatial structure and symmetry of polarizations of vector optical field, providing additional degrees of freedom assisting in controlling the field symmetry at the focus and allowing engineering of the field distribution at the focus to the specific applications.

Efficient Third-Order Distributed Feedback Laser with Enhanced Beam Pattern

NASA Technical Reports Server (NTRS)

Hu, Qing (Inventor); Lee, Alan Wei Min (Inventor); Kao, Tsung-Yu (Inventor)

2015-01-01

A third-order distributed feedback laser has an active medium disposed on a substrate as a linear array of segments having a series of periodically spaced interstices therebetween and a first conductive layer disposed on a surface of the active medium on each of the segments and along a strip from each of the segments to a conductive electrical contact pad for application of current along a path including the active medium. Upon application of a current through the active medium, the active medium functions as an optical waveguide, and there is established an alternating electric field, at a THz frequency, both in the active medium and emerging from the interstices. Spacing of adjacent segments is approximately half of a wavelength of the THz frequency in free space or an odd integral multiple thereof, so that the linear array has a coherence length greater than the length of the linear array.

Optical Control of Living Cells Electrical Activity by Conjugated Polymers.

PubMed

Martino, Nicola; Bossio, Caterina; Vaquero Morata, Susana; Lanzani, Guglielmo; Antognazza, Maria Rosa

2016-01-28

Hybrid interfaces between organic semiconductors and living tissues represent a new tool for in-vitro and in-vivo applications. In particular, conjugated polymers display several optimal properties as substrates for biological systems, such as good biocompatibility, excellent mechanical properties, cheap and easy processing technology, and possibility of deposition on light, thin and flexible substrates. These materials have been employed for cellular interfaces like neural probes, transistors for excitation and recording of neural activity, biosensors and actuators for drug release. Recent experiments have also demonstrated the possibility to use conjugated polymers for all-optical modulation of the electrical activity of cells. Several in-vitro study cases have been reported, including primary neuronal networks, astrocytes and secondary line cells. Moreover, signal photo-transduction mediated by organic polymers has been shown to restore light sensitivity in degenerated retinas, suggesting that these devices may be used for artificial retinal prosthesis in the future. All in all, light sensitive conjugated polymers represent a new approach for optical modulation of cellular activity. In this work, all the steps required to fabricate a bio-polymer interface for optical excitation of living cells are described. The function of the active interface is to transduce the light stimulus into a modulation of the cell membrane potential. As a study case, useful for in-vitro studies, a polythiophene thin film is used as the functional, light absorbing layer, and Human Embryonic Kidney (HEK-293) cells are employed as the biological component of the interface. Practical examples of successful control of the cell membrane potential upon stimulation with light pulses of different duration are provided. In particular, it is shown that both depolarizing and hyperpolarizing effects on the cell membrane can be achieved depending on the duration of the light stimulus. The reported protocol is of general validity and can be straightforwardly extended to other biological preparations.

Cholinergic modulation of activation sequence in the atrial myocardium of non-mammalian vertebrates.

PubMed

Abramochkin, Denis V; Kuzmin, Vladislav S; Sukhova, Galina S; Rosenshtraukh, Leonid V

2010-02-01

Cholinergic changes of electric activity were studied in isolated atrium preparations from fishes (cod and carp), amphibians (frog) and reptilians (lizard) using the microelectrode technique and high-resolution optical mapping. Perfusion of isolated atrium with acetylcholine (10(-6)-5.10(-5) M) caused gradual suppression of action potential generation and, eventually, completely blocked the excitation in a part of the preparation. Other regions of atrium, situated close to the sinoatrial and atrioventricular junctions, remained excitable. Such cholinergic suppression of electric activity was observed in the atrial myocardium of frog and in both fish species, but not in reptilians. Ba(2+) (10(-4) M), which blocks the acetylcholine-dependent potassium current (I(KACh)), prevented cholinergic reduction of action potential amplitude. In several preparations of frog atrium, cholinergic suppression of excitation coincided with episodes of atrial fibrillation. We conclude that the phenomenon of cholinergic suppression of electric activity is typical for atria of fishes and amphibians. It is likely to be caused by I(KACh) activation and may be important for initiation of atrial arrhythmias. 2009 Elsevier Inc. All rights reserved.

Deep-subwavelength imaging of both electric and magnetic localized optical fields by plasmonic campanile nanoantenna

DOE PAGES

Caselli, Niccolò; La China, Federico; Bao, Wei; ...

2015-06-05

Tailoring the electromagnetic field at the nanoscale has led to artificial materials exhibiting fascinating optical properties unavailable in naturally occurring substances. Besides having fundamental implications for classical and quantum optics, nanoscale metamaterials provide a platform for developing disruptive novel technologies, in which a combination of both the electric and magnetic radiation field components at optical frequencies is relevant to engineer the light-matter interaction. Thus, an experimental investigation of the spatial distribution of the photonic states at the nanoscale for both field components is of crucial importance. Here we experimentally demonstrate a concomitant deep-subwavelength near-field imaging of the electric and magneticmore » intensities of the optical modes localized in a photonic crystal nanocavity. We take advantage of the “campanile tip”, a plasmonic near-field probe that efficiently combines broadband field enhancement with strong far-field to near-field coupling. In conclusion, by exploiting the electric and magnetic polarizability components of the campanile tip along with the perturbation imaging method, we are able to map in a single measurement both the electric and magnetic localized near-field distributions.« less

Single-sensor system for spatially resolved, continuous, and multiparametric optical mapping of cardiac tissue

PubMed Central

Lee, Peter; Bollensdorff, Christian; Quinn, T. Alexander; Wuskell, Joseph P.; Loew, Leslie M.; Kohl, Peter

2011-01-01

Background Simultaneous optical mapping of multiple electrophysiologically relevant parameters in living myocardium is desirable for integrative exploration of mechanisms underlying heart rhythm generation under normal and pathophysiologic conditions. Current multiparametric methods are technically challenging, usually involving multiple sensors and moving parts, which contributes to high logistic and economic thresholds that prevent easy application of the technique. Objective The purpose of this study was to develop a simple, affordable, and effective method for spatially resolved, continuous, simultaneous, and multiparametric optical mapping of the heart, using a single camera. Methods We present a new method to simultaneously monitor multiple parameters using inexpensive off-the-shelf electronic components and no moving parts. The system comprises a single camera, commercially available optical filters, and light-emitting diodes (LEDs), integrated via microcontroller-based electronics for frame-accurate illumination of the tissue. For proof of principle, we illustrate measurement of four parameters, suitable for ratiometric mapping of membrane potential (di-4-ANBDQPQ) and intracellular free calcium (fura-2), in an isolated Langendorff-perfused rat heart during sinus rhythm and ectopy, induced by local electrical or mechanical stimulation. Results The pilot application demonstrates suitability of this imaging approach for heart rhythm research in the isolated heart. In addition, locally induced excitation, whether stimulated electrically or mechanically, gives rise to similar ventricular propagation patterns. Conclusion Combining an affordable camera with suitable optical filters and microprocessor-controlled LEDs, single-sensor multiparametric optical mapping can be practically implemented in a simple yet powerful configuration and applied to heart rhythm research. The moderate system complexity and component cost is destined to lower the threshold to broader application of functional imaging and to ease implementation of more complex optical mapping approaches, such as multiparametric panoramic imaging. A proof-of-principle application confirmed that although electrically and mechanically induced excitation occur by different mechanisms, their electrophysiologic consequences downstream from the point of activation are not dissimilar. PMID:21459161

Optimization of Pockels electric field in transverse modulated optical voltage sensor

NASA Astrophysics Data System (ADS)

Huang, Yifan; Xu, Qifeng; Chen, Kun-Long; Zhou, Jie

2018-05-01

This paper investigates the possibilities of optimizing the Pockels electric field in a transverse modulated optical voltage sensor with a spherical electrode structure. The simulations show that due to the edge effect and the electric field concentrations and distortions, the electric field distributions in the crystal are non-uniform. In this case, a tiny variation in the light path leads to an integral error of more than 0.5%. Moreover, a 2D model cannot effectively represent the edge effect, so a 3D model is employed to optimize the electric field distributions. Furthermore, a new method to attach a quartz crystal to the electro-optic crystal along the electric field direction is proposed to improve the non-uniformity of the electric field. The integral error is reduced therefore from 0.5% to 0.015% and less. The proposed method is simple, practical and effective, and it has been validated by numerical simulations and experimental tests.

Dynamic Photochemical and Optoelectronic Control of Photonic Fano Resonances via Monolayer MoS2 Trions.

PubMed

Zhang, Xingwang; Biekert, Nicolas; Choi, Shinhyuk; Naylor, Carl H; De-Eknamkul, Chawina; Huang, Wenzhuo; Zhang, Xiaojie; Zheng, Xiaorui; Wang, Dake; Johnson, A T Charlie; Cubukcu, Ertugrul

2018-02-14

Active tunability of photonic resonances is of great interest for various applications such as optical switching and modulation based on optoelectronic materials. Manipulation of charged excitons in atomically thin transition metal dichalcogenides (TMDCs) like monolayer MoS 2 offers an unexplored route for diverse functionalities in optoelectronic nanodevices. Here, we experimentally demonstrate the dynamic photochemical and optoelectronic control of the photonic crystal Fano resonances by optical and electrical tuning of monolayer MoS 2 refractive index via trions without any chemical treatment. The strong spatial and spectral overlap between the photonic Fano mode and the active MoS 2 monolayer enables efficient modulation of the Fano resonance. Our approach offers new directions for potential applications in the development of optical modulators based on emerging 2D direct band gap semiconductors.

Optical and electrical properties of indium tin oxide films near their laser damage threshold [Electrical and optical properties of indium tin oxide films under multi-pulse laser irradiation at 1064 nm

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yoo, Jae -Hyuck; Lange, Andrew; Bude, Jeff

In this paper, we investigated whether the optical and electrical properties of indium tin oxide (ITO) films are degraded under laser irradiation below their laser ablation threshold. While performing multi-pulse laser damage experiments on a single ITO film (4.7 ns, 1064 nm, 10 Hz), we examined the optical and electrical properties in situ. A decrease in reflectance was observed prior to laser damage initiation. However, under sub-damage threshold irradiation, conductivity and reflectance of the film were maintained without measurable degradation. This indicates that ITO films in optoelectronic devices may be operated below their lifetime laser damage threshold without noticeable performancemore » degradation.« less

Optical and electrical properties of indium tin oxide films near their laser damage threshold [Electrical and optical properties of indium tin oxide films under multi-pulse laser irradiation at 1064 nm

DOE PAGES

Yoo, Jae -Hyuck; Lange, Andrew; Bude, Jeff; ...

2017-02-10

In this paper, we investigated whether the optical and electrical properties of indium tin oxide (ITO) films are degraded under laser irradiation below their laser ablation threshold. While performing multi-pulse laser damage experiments on a single ITO film (4.7 ns, 1064 nm, 10 Hz), we examined the optical and electrical properties in situ. A decrease in reflectance was observed prior to laser damage initiation. However, under sub-damage threshold irradiation, conductivity and reflectance of the film were maintained without measurable degradation. This indicates that ITO films in optoelectronic devices may be operated below their lifetime laser damage threshold without noticeable performancemore » degradation.« less

Influence of spray time on the optical and electrical properties of CoNi2S4 thin films

NASA Astrophysics Data System (ADS)

El Radaf, I. M.; Fouad, S. S.; Ismail, A. M.; Sakr, G. B.

2018-04-01

In this paper, a facile spray pyrolysis technique was utilized to synthesize CoNi2S4 thin films. The influence of spray time on the structural, optical and electrical properties of the CoNi2S4 thin films was studied. The x-ray diffraction studies of the CoNi2S4 thin films illustrate that the films exhibit a polycrystalline nature with cubic structure. The values of the lattice strain ε, and the dislocation density δ, were decreased as the spray time increase while the grain size has reverse manner to lattice strain ε, and the dislocation density δ. The transmittance and reflectance spectra of the CoNi2S4 thin films were recorded in the wavelength range of (400–2500) nm to evaluate the optical parameters of the CoNi2S4 thin films. Optical absorption coefficient of CoNi2S4 thin films revealed a presence of a direct energy gap and the values of energy gap were decreased from 1.68 to 1.53 eV as the spray time increases from 15 min to 45 min. The nonlinear refractive index of the CoNi2S4 thin films was increased with increasing of the spray time. The CoNi2S4 thin films exhibit single activation energy and the activation energy was decreased as the spray time increased.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tauke-Pedretti, Anna; Skogen, Erik J; Vawter, Gregory A

An optical sampler includes a first and second 1.times.n optical beam splitters splitting an input optical sampling signal and an optical analog input signal into n parallel channels, respectively, a plurality of optical delay elements providing n parallel delayed input optical sampling signals, n photodiodes converting the n parallel optical analog input signals into n respective electrical output signals, and n optical modulators modulating the input optical sampling signal or the optical analog input signal by the respective electrical output signals, and providing n successive optical samples of the optical analog input signal. A plurality of output photodiodes and eADCsmore » convert the n successive optical samples to n successive digital samples. The optical modulator may be a photodiode interconnected Mach-Zehnder Modulator. A method of sampling the optical analog input signal is disclosed.« less

Novel monolithic integration scheme for high-speed electroabsorption modulators and semiconductor optical amplifiers using cascaded structure.

PubMed

Lin, Fang-Zheng; Wu, Tsu-Hsiu; Chiu, Yi-Jen

2009-06-08

A new monolithic integration scheme, namely cascaded-integration (CI), for improving high-speed optical modulation is proposed and demonstrated. High-speed electroabsorption modulators (EAMs) and semiconductor optical amplifiers (SOAs) are taken as the integrated elements of CI. This structure is based on an optical waveguide defined by cascading segmented EAMs with segmented SOAs, while high-impedance transmission lines (HITLs) are used for periodically interconnecting EAMs, forming a distributive optical re-amplification and re-modulation. Therefore, not only the optical modulation can be beneficial from SOA gain, but also high electrical reflection due to EAM low characteristic impedance can be greatly reduced. Two integration schemes, CI and conventional single-section (SS), with same total EAM- and SOA- lengths are fabricated and compared to examine the concept. Same modulation-depth against with EAM bias (up to 5V) as well as SOA injection current (up to 60mA) is found in both structures. In comparison with SS, a < 1dB extra optical-propagation loss in CI is measured due to multi-sections of electrical-isolation regions between EAMs and SOAs, suggesting no significant deterioration in CI on DC optical modulation efficiency. Lower than -12dB of electrical reflection from D.C. to 30GHz is observed in CI, better than -5dB reflection in SS for frequency of above 5GHz. Superior high-speed electrical properties in CI structure can thus lead to higher speed of electrical-to-optical (EO) response, where -3dB bandwidths are >30GHz and 13GHz for CI and SS respectively. Simulation results on electrical and EO response are quite consistent with measurement, confirming that CI can lower the driving power at high-speed regime, while the optical loss is still kept the same level. Taking such distributive advantage (CI) with optical gain, not only higher-speed modulation with high output optical power can be attained, but also the trade-off issue due to impedance mismatch can be released to reduce the driving power of modulator. Such kind of monolithic integration scheme also has potential for the applications of other high-speed optoelectronics devices.

SPECIAL ISSUE ON OPTICAL PROCESSING OF INFORMATION: Semiconductor-laser Fourier processors of electric signals

NASA Astrophysics Data System (ADS)

Blok, A. S.; Bukhenskii, A. F.; Krupitskii, É. I.; Morozov, S. V.; Pelevin, V. Yu; Sergeenko, T. N.; Yakovlev, V. I.

1995-10-01

An investigation is reported of acousto-optical and fibre-optic Fourier processors of electric signals, based on semiconductor lasers. A description is given of practical acousto-optical processors with an analysis band 120 MHz wide, a resolution of 200 kHz, and 7 cm × 8 cm × 18 cm dimensions. Fibre-optic Fourier processors are considered: they represent a new class of devices which are promising for the processing of gigahertz signals.

Measurement of the internal stress and electric field in a resonating piezoelectric transformer for high-voltage applications using the electro-optic and photoelastic effects.

PubMed

VanGordon, James A; Kovaleski, Scott D; Norgard, Peter; Gall, Brady B; Dale, Gregory E

2014-02-01

The high output voltages from piezoelectric transformers are currently being used to accelerate charged particle beams for x-ray and neutron production. Traditional methods of characterizing piezoelectric transformers (PTs) using electrical probes can decrease the voltage transformation ratio of the device due to the introduction of load impedances on the order of hundreds of kiloohms to hundreds of megaohms. Consequently, an optical diagnostic was developed that used the photoelastic and electro-optic effects present in piezoelectric materials that are transparent to a given optical wavelength to determine the internal stress and electric field. The combined effects of the piezoelectric, photoelastic, and electro-optic effects result in a time-dependent change the refractive indices of the material and produce an artificially induced, time-dependent birefringence in the piezoelectric material. This induced time-dependent birefringence results in a change in the relative phase difference between the ordinary and extraordinary wave components of a helium-neon laser beam. The change in phase difference between the wave components was measured using a set of linear polarizers. The measured change in phase difference was used to calculate the stress and electric field based on the nonlinear optical properties, the piezoelectric constitutive equations, and the boundary conditions of the PT. Maximum stresses of approximately 10 MPa and electric fields of as high as 6 kV/cm were measured with the optical diagnostic. Measured results were compared to results from both a simple one-dimensional (1D) model of the piezoelectric transformer and a three-dimensional (3D) finite element model. Measured stresses and electric fields along the length of an operating length-extensional PT for two different electrical loads were within at least 50 % of 3D finite element simulated results. Additionally, the 3D finite element results were more accurate than the results from the 1D model for a wider range of electrical load impedances under test.

Group-Velocity-Controlled and Gate-Tunable Directional Excitation of Polaritons in Graphene-Boron Nitride Heterostructures

NASA Astrophysics Data System (ADS)

Jiang, Yuyu; Lin, Xiao; Low, Tony; Zhang, Baile; Chen, Hongsheng

2018-05-01

A fundamental building block in nano-photonics is the ability to directionally excite highly squeezed optical mode dynamically, particularly with an electrical bias. Such capabilities would enable the active manipulation of light propagation for information processing and transfer. However, when the optical source is built-in, it remains challenging to steer the excitation directionality in a flexible way. Here, we reveal a novel mechanism for tunable directional excitation of highly squeezed polaritons in graphene-hexagonal boron nitride (hBN) heterostructures. The effect relies on controlling the sign of the group velocity of the coupled plasmon-phonon polaritons, which can be flipped by simply tuning the chemical potential of graphene (through electrostatic gating) in the heterostructures. Graphene-hBN heterostructure thus present a promising platform toward nano-photonic circuits and nano-devices with electrically reconfigurable functionalities.

Simultaneous optical and electrical recording of a single ion-channel.

PubMed

Ide, Toru; Takeuchi, Yuko; Aoki, Takaaki; Yanagida, Toshio

2002-10-01

In recent years, the single-molecule imaging technique has proven to be a valuable tool in solving many basic problems in biophysics. The technique used to measure single-molecule functions was initially developed to study electrophysiological properties of channel proteins. However, the technology to visualize single channels at work has not received as much attention. In this study, we have for the first time, simultaneously measured the optical and electrical properties of single-channel proteins. The large conductance calcium-activated potassium channel (BK-channel) labeled with fluorescent dye molecules was incorporated into a planar bilayer membrane and the fluorescent image captured with a total internal reflection fluorescence microscope simultaneously with single-channel current recording. This innovative technology will greatly advance the study of channel proteins as well as signal transduction processes that involve ion permeation processes.

Low substrate temperature fabrication of high-performance metal oxide thin-film by magnetron sputtering with target self-heating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, W. F.; Institute of Materials Research and Engineering, Agency for Science, Technology and Research; Liu, Z. G.

2013-03-18

Al-doped ZnO (AZO) films with high transmittance and low resistivity were achieved on low temperature substrates by radio frequency magnetron sputtering using a high temperature target. By investigating the effect of target temperature (T{sub G}) on electrical and optical properties, the origin of electrical conduction is verified as the effect of the high T{sub G}, which enhances crystal quality that provides higher mobility of electrons as well as more effective activation for the Al dopants. The optical bandgap increases from 3.30 eV for insulating ZnO to 3.77 eV for conducting AZO grown at high T{sub G}, and is associated withmore » conduction-band filling up to 1.13 eV due to the Burstein-Moss effect.« less

Electrically tunable graphene plasmonic quasicrystal metasurfaces for transformation optics

PubMed Central

Zeng, Chao; Liu, Xueming; Wang, Guoxi

2014-01-01

The past few years have witnessed tremendous achievements of transformation optics applied to metallic plasmonic systems. Due to the poor tunability of metals, however, the ultimate control over surface plasmons remains a challenge. Here we propose a new type of graphene plasmonic (GP) metasurfaces by shaping the dielectrics underneath monolayer graphene into specific photonic crystals. The radial and axial gradient-index (GRIN) lenses are implemented to demonstrate the feasibility and versatility of the proposal. It is found that the designed GP-GRIN lenses work perfectly well for focusing, collimating, and guiding the GP waves. Especially, they exhibit excellent performances in the THz regime as diverse as ultra-small focusing spot (λ0/60) and broadband electrical tunability. The proposed method offers potential opportunities in exploiting active transformational plasmonic elements operating at THz frequencies. PMID:25042132

Electrical Identification and Selective Microstimulation of Neuronal Compartments Based on Features of Extracellular Action Potentials

NASA Astrophysics Data System (ADS)

Radivojevic, Milos; Jäckel, David; Altermatt, Michael; Müller, Jan; Viswam, Vijay; Hierlemann, Andreas; Bakkum, Douglas J.

2016-08-01

A detailed, high-spatiotemporal-resolution characterization of neuronal responses to local electrical fields and the capability of precise extracellular microstimulation of selected neurons are pivotal for studying and manipulating neuronal activity and circuits in networks and for developing neural prosthetics. Here, we studied cultured neocortical neurons by using high-density microelectrode arrays and optical imaging, complemented by the patch-clamp technique, and with the aim to correlate morphological and electrical features of neuronal compartments with their responsiveness to extracellular stimulation. We developed strategies to electrically identify any neuron in the network, while subcellular spatial resolution recording of extracellular action potential (AP) traces enabled their assignment to the axon initial segment (AIS), axonal arbor and proximal somatodendritic compartments. Stimulation at the AIS required low voltages and provided immediate, selective and reliable neuronal activation, whereas stimulation at the soma required high voltages and produced delayed and unreliable responses. Subthreshold stimulation at the soma depolarized the somatic membrane potential without eliciting APs.

Nanoelectronics enabled chronic multimodal neural platform in a mouse ischemic model

PubMed Central

Luan, Lan; Sullender, Colin T.; Li, Xue; Zhao, Zhengtuo; Zhu, Hanlin; Wei, Xiaoling; Xie, Chong; Dunn, Andrew K.

2018-01-01

Background Despite significant advancements of optical imaging techniques for mapping hemodynamics in small animal models, it remains challenging to combine imaging with spatially resolved electrical recording of individual neurons especially for longitudinal studies. This is largely due to the strong invasiveness to the living brain from the penetrating electrodes and their limited compatibility with longitudinal imaging. New Method We implant arrays of ultraflexible nanoelectronic threads (NETs) in mice for neural recording both at the brain surface and intracortically, which maintain great tissue compatibility chronically. By mounting a cranial window atop of the NET arrays that allows for chronic optical access, we establish a multimodal platform that combines spatially resolved electrical recording of neural activity and laser speckle contrast imaging (LSCI) of cerebral blood flow (CBF) for longitudinal studies. Results We induce peri-infarct depolarizations (PIDs) by targeted photothrombosis, and show the ability to detect its occurrence and propagation through spatiotemporal variations in both extracellular potentials and CBF. We also demonstrate chronic tracking of single-unit neural activity and CBF over days after photothrombosis, from which we observe reperfusion and increased firing rates. Comparison with Existing Method(s) This multimodal platform enables simultaneous mapping of neural activity and hemodynamic parameters at the microscale for quantitative, longitudinal comparisons with minimal perturbation to the baseline neurophysiology. Conclusion The ability to spatiotemporally resolve and chronically track CBF and neural electrical activity in the same living brain region has broad applications for studying the interplay between neural and hemodynamic responses in health and in cerebrovascular and neurological pathologies. PMID:29203409

Effect of carrier doping and external electric field on the optical properties of graphene quantum dots

NASA Astrophysics Data System (ADS)

Basak, Tista; Basak, Tushima

2018-02-01

In this paper, we demonstrate that the optical properties of finite-sized graphene quantum dots can be effectively controlled by doping it with different types of charge carriers (electron/hole). In addition, the role played by a suitably directed external electric field on the optical absorption of charge-doped graphene quantum dots have also been elucidated. The computations have been performed on diamond-shaped graphene quantum dot (DQD) within the framework of the Pariser-Parr-Pople (PPP) model Hamiltonian, which takes into account long-range Coulomb interactions. Our results reveal that the energy band-gap increases when the DQD is doped with holes while it decreases on doping it with electrons. Further, the optical absorption spectra of DQD exhibits red/blue-shift on doping with electrons/holes. Our computations also indicate that the application of external transverse electric field results in a substantial blue-shift of the optical spectrum for charge-doped DQD. However, it is observed that the influence of charge-doping is more prominent in tuning the optical properties of finite-sized graphene quantum dots as compared to externally applied electric field. Thus, tailoring the optical properties of finite-sized graphene quantum dots by manipulative doping with charge carriers and suitably aligned external electric field can greatly enhance its potential application in designing nano-photonic devices.

Demonstration of 720×720 optical fast circuit switch for intra-datacenter networks

NASA Astrophysics Data System (ADS)

Ueda, Koh; Mori, Yojiro; Hasegawa, Hiroshi; Matsuura, Hiroyuki; Ishii, Kiyo; Kuwatsuka, Haruhiko; Namiki, Shu; Sato, Ken-ichi

2016-03-01

Intra-datacenter traffic is growing more than 20% a year. In typical datacenters, many racks/pods including servers are interconnected via multi-tier electrical switches. The electrical switches necessitate power-consuming optical-to- electrical (OE) and electrical-to-optical (EO) conversion, the power consumption of which increases with traffic. To overcome this problem, optical switches that eliminate costly OE and EO conversion and enable low power consumption switching are being investigated. There are two major requirements for the optical switch. First, it must have a high port count to construct reduced tier intra-datacenter networks. Second, switching speed must be short enough that most of the traffic load can be offloaded from electrical switches. Among various optical switches, we focus on those based on arrayed-waveguide gratings (AWGs), since the AWG is a passive device with minimal power consumption. We previously proposed a high-port-count optical switch architecture that utilizes tunable lasers, route-and-combine switches, and wavelength-routing switches comprised of couplers, erbium-doped fiber amplifiers (EDFAs), and AWGs. We employed conventional external cavity lasers whose wavelength-tuning speed was slower than 100 ms. In this paper, we demonstrate a large-scale optical switch that offers fast wavelength routing. We construct a 720×720 optical switch using recently developed lasers whose wavelength-tuning period is below 460 μs. We evaluate the switching time via bit-error-ratio measurements and achieve 470-μs switching time (includes 10-μs guard time to handle EDFA surge). To best of our knowledge, this is the first demonstration of such a large-scale optical switch with practical switching time.

Electro-Optic Effects in Colloidal Dispersion of Metal Nano-Rods in Dielectric Fluid

PubMed Central

Golovin, Andrii B.; Xiang, Jie; Park, Heung-Shik; Tortora, Luana; Nastishin, Yuriy A.; Shiyanovskii, Sergij V.; Lavrentovich, Oleg D.

2011-01-01

In modern transformation optics, one explores metamaterials with properties that vary from point to point in space and time, suitable for application in devices such as an “optical invisibility cloak” and an “optical black hole”. We propose an approach to construct spatially varying and switchable metamaterials that are based on colloidal dispersions of metal nano-rods (NRs) in dielectric fluids, in which dielectrophoretic forces, originating in the electric field gradients, create spatially varying configurations of aligned NRs. The electric field controls orientation and concentration of NRs and thus modulates the optical properties of the medium. Using gold (Au) NRs dispersed in toluene, we demonstrate electrically induced change in refractive index on the order of 0.1. PMID:28879997

Signal-to-noise ratio of arbitrarily filtered spontaneous emission

NASA Astrophysics Data System (ADS)

Šprem, Marko; Bosiljevac, Marko; Babić, Dubravko

2018-02-01

The signal-to-noise ratio (SNR) of filtered incoherent light can be approximated from the product of the coherence time of the light and the equivalent (electrical) noise bandwidth of the detector. This approximation holds only for the light with very short coherence time, that is in the case where the optical bandwidth of the light is much larger than the electrical bandwidth. We present here an expression for accurate evaluation of the SNR of the filtered incoherent light, which computes SNR from arbitrary shapes of optical and electrical filter power spectral densities (PSD). The PSDs of the filters can be measured using optical and electrical spectrum analyzers. Using our expression, we show that the SNR reaches unity when the electrical filter bandwidth is becoming larger than the optical filter bandwidth. To prove the theory, we evaluate and directly measure SNR of an incoherent light source filtered with several optical filters with bandwidths larger and commensurate with the bandwidth of the detector. For later we used optical and electrical filters with 3-dB bandwidths of 15 GHz and 10 GHz, respectively. Using our expression to evaluate SNR we obtained results in a good agreement with directly measured SNR. The results also prove that the approximation for evaluating SNR does not provide accurate results. The PSD of the detector with large noise bandwidth is difficult to measure using spectrum analyzer. There- fore, we report here a method for measuring the electrical noise bandwidth of the detector using the heterodyne linewidth measurement technique with tunable laser.

Physical principles for scalable neural recording

PubMed Central

Zamft, Bradley M.; Maguire, Yael G.; Shapiro, Mikhail G.; Cybulski, Thaddeus R.; Glaser, Joshua I.; Amodei, Dario; Stranges, P. Benjamin; Kalhor, Reza; Dalrymple, David A.; Seo, Dongjin; Alon, Elad; Maharbiz, Michel M.; Carmena, Jose M.; Rabaey, Jan M.; Boyden, Edward S.; Church, George M.; Kording, Konrad P.

2013-01-01

Simultaneously measuring the activities of all neurons in a mammalian brain at millisecond resolution is a challenge beyond the limits of existing techniques in neuroscience. Entirely new approaches may be required, motivating an analysis of the fundamental physical constraints on the problem. We outline the physical principles governing brain activity mapping using optical, electrical, magnetic resonance, and molecular modalities of neural recording. Focusing on the mouse brain, we analyze the scalability of each method, concentrating on the limitations imposed by spatiotemporal resolution, energy dissipation, and volume displacement. Based on this analysis, all existing approaches require orders of magnitude improvement in key parameters. Electrical recording is limited by the low multiplexing capacity of electrodes and their lack of intrinsic spatial resolution, optical methods are constrained by the scattering of visible light in brain tissue, magnetic resonance is hindered by the diffusion and relaxation timescales of water protons, and the implementation of molecular recording is complicated by the stochastic kinetics of enzymes. Understanding the physical limits of brain activity mapping may provide insight into opportunities for novel solutions. For example, unconventional methods for delivering electrodes may enable unprecedented numbers of recording sites, embedded optical devices could allow optical detectors to be placed within a few scattering lengths of the measured neurons, and new classes of molecularly engineered sensors might obviate cumbersome hardware architectures. We also study the physics of powering and communicating with microscale devices embedded in brain tissue and find that, while radio-frequency electromagnetic data transmission suffers from a severe power–bandwidth tradeoff, communication via infrared light or ultrasound may allow high data rates due to the possibility of spatial multiplexing. The use of embedded local recording and wireless data transmission would only be viable, however, given major improvements to the power efficiency of microelectronic devices. PMID:24187539

Roadmap on neurophotonics

NASA Astrophysics Data System (ADS)

Cho, Yong Ku; Zheng, Guoan; Augustine, George J.; Hochbaum, Daniel; Cohen, Adam; Knöpfel, Thomas; Pisanello, Ferruccio; Pavone, Francesco S.; Vellekoop, Ivo M.; Booth, Martin J.; Hu, Song; Zhu, Jiang; Chen, Zhongping; Hoshi, Yoko

2016-09-01

Mechanistic understanding of how the brain gives rise to complex behavioral and cognitive functions is one of science’s grand challenges. The technical challenges that we face as we attempt to gain a systems-level understanding of the brain are manifold. The brain’s structural complexity requires us to push the limit of imaging resolution and depth, while being able to cover large areas, resulting in enormous data acquisition and processing needs. Furthermore, it is necessary to detect functional activities and ‘map’ them onto the structural features. The functional activity occurs at multiple levels, using electrical and chemical signals. Certain electrical signals are only decipherable with sub-millisecond timescale resolution, while other modes of signals occur in minutes to hours. For these reasons, there is a wide consensus that new tools are necessary to undertake this daunting task. Optical techniques, due to their versatile and scalable nature, have great potentials to answer these challenges. Optical microscopy can now image beyond the diffraction limit, record multiple types of brain activity, and trace structural features across large areas of tissue. Genetically encoded molecular tools opened doors to controlling and detecting neural activity using light in specific cell types within the intact brain. Novel sample preparation methods that reduce light scattering have been developed, allowing whole brain imaging in rodent models. Adaptive optical methods have the potential to resolve images from deep brain regions. In this roadmap article, we showcase a few major advances in this area, survey the current challenges, and identify potential future needs that may be used as a guideline for the next steps to be taken.

Roadmap on neurophotonics

PubMed Central

Cho, Yong Ku; Zheng, Guoan; Augustine, George J; Hochbaum, Daniel; Cohen, Adam; Knöpfel, Thomas; Pisanello, Ferruccio; Pavone, Francesco S; Vellekoop, Ivo M; Booth, Martin J; Hu, Song; Zhu, Jiang; Chen, Zhongping; Hoshi, Yoko

2017-01-01

Mechanistic understanding of how the brain gives rise to complex behavioral and cognitive functions is one of science’s grand challenges. The technical challenges that we face as we attempt to gain a systems-level understanding of the brain are manifold. The brain’s structural complexity requires us to push the limit of imaging resolution and depth, while being able to cover large areas, resulting in enormous data acquisition and processing needs. Furthermore, it is necessary to detect functional activities and ‘map’ them onto the structural features. The functional activity occurs at multiple levels, using electrical and chemical signals. Certain electrical signals are only decipherable with sub-millisecond timescale resolution, while other modes of signals occur in minutes to hours. For these reasons, there is a wide consensus that new tools are necessary to undertake this daunting task. Optical techniques, due to their versatile and scalable nature, have great potentials to answer these challenges. Optical microscopy can now image beyond the diffraction limit, record multiple types of brain activity, and trace structural features across large areas of tissue. Genetically encoded molecular tools opened doors to controlling and detecting neural activity using light in specific cell types within the intact brain. Novel sample preparation methods that reduce light scattering have been developed, allowing whole brain imaging in rodent models. Adaptive optical methods have the potential to resolve images from deep brain regions. In this roadmap article, we showcase a few major advances in this area, survey the current challenges, and identify potential future needs that may be used as a guideline for the next steps to be taken. PMID:28386392

Real-time digital signal processing for live electro-optic imaging.

PubMed

Sasagawa, Kiyotaka; Kanno, Atsushi; Tsuchiya, Masahiro

2009-08-31

We present an imaging system that enables real-time magnitude and phase detection of modulated signals and its application to a Live Electro-optic Imaging (LEI) system, which realizes instantaneous visualization of RF electric fields. The real-time acquisition of magnitude and phase images of a modulated optical signal at 5 kHz is demonstrated by imaging with a Si-based high-speed CMOS image sensor and real-time signal processing with a digital signal processor. In the LEI system, RF electric fields are probed with light via an electro-optic crystal plate and downconverted to an intermediate frequency by parallel optical heterodyning, which can be detected with the image sensor. The artifacts caused by the optics and the image sensor characteristics are corrected by image processing. As examples, we demonstrate real-time visualization of electric fields from RF circuits.

Photothermally tunable silicon-microring-based optical add-drop filter through integrated light absorber.

PubMed

Chen, Xi; Shi, Yuechun; Lou, Fei; Chen, Yiting; Yan, Min; Wosinski, Lech; Qiu, Min

2014-10-20

An optically pumped thermo-optic (TO) silicon ring add-drop filter with fast thermal response is experimentally demonstrated. We propose that metal-insulator-metal (MIM) light absorber can be integrated into silicon TO devices, acting as a localized heat source which can be activated remotely by a pump beam. The MIM absorber design introduces less thermal capacity to the device, compared to conventional electrically-driven approaches. Experimentally, the absorber-integrated add-drop filter shows an optical response time of 13.7 μs following the 10%-90% rule (equivalent to a exponential time constant of 5 μs) and a wavelength shift over pump power of 60 pm/mW. The photothermally tunable add-drop filter may provide new perspectives for all-optical routing and switching in integrated Si photonic circuits.

Au doping effects on electrical and optical properties of vanadium dioxides

NASA Astrophysics Data System (ADS)

Zhu, YaBin; He, Fan; Na, Jie

2012-03-01

Vanadium dioxides were fabricated on normal glass substrates using reactive radio frequency (RF) magnetron sputtering. The oxygen flow volume and annealed temperatures as growth parameters are systematically investigated. The electrical and optical properties of VO2 and Au:VO2 thin films with different growth conditions are discussed. The semiconductor-metal phase transition temperature decreased by ˜10°C for the sample with Au doping compared to the sample without Au doping. However, the optical transmittance of Au:VO2 thin films is much lower than that of bare VO2. These results show that Au doping has a marked effect on the electrical and optical properties.

A chip-scale integrated cavity-electro-optomechanics platform.

PubMed

Winger, M; Blasius, T D; Mayer Alegre, T P; Safavi-Naeini, A H; Meenehan, S; Cohen, J; Stobbe, S; Painter, O

2011-12-05

We present an integrated optomechanical and electromechanical nanocavity, in which a common mechanical degree of freedom is coupled to an ultrahigh-Q photonic crystal defect cavity and an electrical circuit. The system allows for wide-range, fast electrical tuning of the optical nanocavity resonances, and for electrical control of optical radiation pressure back-action effects such as mechanical amplification (phonon lasing), cooling, and stiffening. These sort of integrated devices offer a new means to efficiently interconvert weak microwave and optical signals, and are expected to pave the way for a new class of micro-sensors utilizing optomechanical back-action for thermal noise reduction and low-noise optical read-out.

Electro-optic response in thin smectic C* film with chevron structures

NASA Astrophysics Data System (ADS)

Kudreyko, Aleksey A.; Migranov, Nail G.; Migranova, Dana N.

2016-12-01

The effects in electrostatic models of chevron surface-stabilized ferroelectric liquid crystals are investigated through numerical modeling. To study smectic C* director distribution within the cell, we consider two nonlinear approaches: the chevron interface does not interplay with the electric field; the electric field interplays with the chevron interface. The obtained results of the director field distribution are compared with the earlier linearized studies. We find that whether or not the electric field interplays with the chevron interface, the electro-optic response requires a generalized approach for its description. The threshold electric field, which is necessary for switching between two stable director states in the chevron cell is evaluated. This study suggests that, in many cases of practical interest, electro-optic response to the electric field and the threshold electric field can be precisely estimated. We argue that, beside being numerically efficient, our approach provides a convenient and a novel standpoint for looking at the electro-optic response problem. Project supported by the Russian Foundation for Basic Research (RFBR) (Grant Nos. 16-32-00043 and 14-02-97026).

Tuning the Electronic, Optical, and Magnetic Properties of Monolayer GaSe with a Vertical Electric Field

NASA Astrophysics Data System (ADS)

Ke, Congming; Wu, Yaping; Guo, Guang-Yu; Lin, Wei; Wu, Zhiming; Zhou, Changjie; Kang, Junyong

2018-04-01

Inspired by two-dimensional material with their unique physical properties and innovative device applications, here we report a design framework on monolayer GaSe, an important member of the two-dimensional material family, in an effort to tune the electronic, optical, and magnetic properties through a vertical electric field. A transition from indirect to direct band gap in monolayer GaSe is found with an electric field of 0.09 V /Å . The giant Stark effect results in a reduction of the band gap with a Stark coefficient of 3.54 Å. Optical and dielectric properties of monolayer GaSe are dependent on the vertical electric field. A large regulation range for polarization E ∥c ^ is found for the static dielectric constant. The optical anisotropy with the dipole transition from E ∥c ^ to E ⊥c ^ is achieved. Induced by the spin-orbit coupling, spin-splitting energy at the valence band maximum increases linearly with the electric field. The effective mass of holes is highly susceptible to the vertical electric field. Switchable spin-polarization features in spin texture of monolayer GaSe are predicted. The tunable electronic, optical, and magnetic properties of monolayer GaSe hold great promise for applications in both the optoelectronic and spintronic devices.

Electro-optical Probing Of Terahertz Integrated Circuits

NASA Technical Reports Server (NTRS)

Bhasin, K. B.; Romanofsky, R.; Whitaker, J. F.; Valdmanis, J. A.; Mourou, G.; Jackson, T. A.

1990-01-01

Electro-optical probe developed to perform noncontact, nondestructive, and relatively noninvasive measurements of electric fields over broad spectrum at millimeter and shorter wavelengths in integrated circuits. Manipulated with conventional intregrated-circuit-wafer-probing equipment and operated without any special preparation of integrated circuits. Tip of probe small electro-optical crystal serving as proximity electric-field sensor.

Electro-Optic Analog/Digital Converter.

DTIC Science & Technology

electro - optic material and a source of linearly polarized light is arranged to transmit its light energy along each of the optical waveguides. Electrodes are disposed contiguous to the optical waveguides for impressing electric fields thereacross. An input signal potential is applied to the electrodes to produce electric fields of intensity relative to each of the waveguides such that causes phase shift and resultant change of polarization which can be detected as representative of a binary ’one’ or binary ’zero’ for each of the channel optical

Resonant optical device with a microheater

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lentine, Anthony L.; DeRose, Christopher

2017-04-04

A resonant photonic device is provided. The device comprises an optical waveguiding element, such as an optical resonator, that includes a diode junction region, two signal terminals configured to apply a bias voltage across the junction region, and a heater laterally separated from the optical waveguiding element. A semiconductor electrical barrier element is juxtaposed to the heater. A metallic strip is electrically and thermally connected at one end to a signal terminal of the optical waveguiding element and thermally connected at another end to the barrier element.

Spoked-ring microcavities: enabling seamless integration of nanophotonics in unmodified advanced CMOS microelectronics chips

NASA Astrophysics Data System (ADS)

Wade, Mark T.; Shainline, Jeffrey M.; Orcutt, Jason S.; Ram, Rajeev J.; Stojanovic, Vladimir; Popovic, Milos A.

2014-03-01

We present the spoked-ring microcavity, a nanophotonic building block enabling energy-efficient, active photonics in unmodified, advanced CMOS microelectronics processes. The cavity is realized in the IBM 45nm SOI CMOS process - the same process used to make many commercially available microprocessors including the IBM Power7 and Sony Playstation 3 processors. In advanced SOI CMOS processes, no partial etch steps and no vertical junctions are available, which limits the types of optical cavities that can be used for active nanophotonics. To enable efficient active devices with no process modifications, we designed a novel spoked-ring microcavity which is fully compatible with the constraints of the process. As a modulator, the device leverages the sub-100nm lithography resolution of the process to create radially extending p-n junctions, providing high optical fill factor depletion-mode modulation and thereby eliminating the need for a vertical junction. The device is made entirely in the transistor active layer, low-loss crystalline silicon, which eliminates the need for a partial etch commonly used to create ridge cavities. In this work, we present the full optical and electrical design of the cavity including rigorous mode solver and FDTD simulations to design the Qlimiting electrical contacts and the coupling/excitation. We address the layout of active photonics within the mask set of a standard advanced CMOS process and show that high-performance photonic devices can be seamlessly monolithically integrated alongside electronics on the same chip. The present designs enable monolithically integrated optoelectronic transceivers on a single advanced CMOS chip, without requiring any process changes, enabling the penetration of photonics into the microprocessor.

Multi-scale theory-assisted nano-engineering of plasmonic-organic hybrid electro-optic device performance

NASA Astrophysics Data System (ADS)

Elder, Delwin L.; Johnson, Lewis E.; Tillack, Andreas F.; Robinson, Bruce H.; Haffner, Christian; Heni, Wolfgang; Hoessbacher, Claudia; Fedoryshyn, Yuriy; Salamin, Yannick; Baeuerle, Benedikt; Josten, Arne; Ayata, Masafumi; Koch, Ueli; Leuthold, Juerg; Dalton, Larry R.

2018-02-01

Multi-scale (correlated quantum and statistical mechanics) modeling methods have been advanced and employed to guide the improvement of organic electro-optic (OEO) materials, including by analyzing electric field poling induced electro-optic activity in nanoscopic plasmonic-organic hybrid (POH) waveguide devices. The analysis of in-device electro-optic activity emphasizes the importance of considering both the details of intermolecular interactions within organic electro-optic materials and interactions at interfaces between OEO materials and device architectures. Dramatic improvement in electro-optic device performance-including voltage-length performance, bandwidth, energy efficiency, and lower optical losses have been realized. These improvements are critical to applications in telecommunications, computing, sensor technology, and metrology. Multi-scale modeling methods illustrate the complexity of improving the electro-optic activity of organic materials, including the necessity of considering the trade-off between improving poling-induced acentric order through chromophore modification and the reduction of chromophore number density associated with such modification. Computational simulations also emphasize the importance of developing chromophore modifications that serve multiple purposes including matrix hardening for enhanced thermal and photochemical stability, control of matrix dimensionality, influence on material viscoelasticity, improvement of chromophore molecular hyperpolarizability, control of material dielectric permittivity and index of refraction properties, and control of material conductance. Consideration of new device architectures is critical to the implementation of chipscale integration of electronics and photonics and achieving the high bandwidths for applications such as next generation (e.g., 5G) telecommunications.

Study of optical design of Blu-ray pickup head system with a liquid crystal element.

PubMed

Fang, Yi-Chin; Yen, Chih-Ta; Hsu, Jui-Hsin

2014-10-10

This paper proposes a newly developed optical design and an active compensation method for a Blu-ray pickup head system with a liquid crystal (LC) element. Different from traditional pickup lens design, this new optical design delivers performance as good as the conventional one but has more room for tolerance control, which plays a role in antishaking devices, such as portable Blu-ray players. A hole-pattern electrode and LC optics with external voltage input were employed to generate a symmetric nonuniform electrical field in the LC layer that directs LC molecules into the appropriate gradient refractive index distribution, resulting in the convergence or divergence of specific light beams. LC optics deliver fast and, most importantly, active compensation through optical design when errors occur. Simulations and tolerance analysis were conducted using Code V software, including various tolerance analyses, such as defocus, tilt, and decenter, and their related compensations. Two distinct Blu-ray pickup head system designs were examined in this study. In traditional Blu-ray pickup head system designs, the aperture stop is always set on objective lenses. In the study, the aperture stop is on the LC lens as a newly developed lens. The results revealed that an optical design with aperture stop set on the LC lens as an active compensation device successfully eliminated up to 57% of coma aberration compared with traditional optical designs so that this pickup head lens design will have more space for tolerance control.

ALTUS Cumulus Electrification Study (ACES)

NASA Technical Reports Server (NTRS)

Kim, Tony; Blakeslee, Richard; Russell, Larry W. (Technical Monitor)

2002-01-01

The ALTUS Cumulus Electrification Study (ACES) is an uninhabited aerial vehicle (UAV)-based project that will investigate thunderstorms in the vicinity of the Florida Everglades in August 2002. ACES is being conducted to both investigate storm electrical activity and its relationship to storm morphology, and validate Tropical Rainfall Measurement Mission (TRMM) satellite measurements. In addition, as part of NASA's UAV-based science demonstration program, this project will provide a scientifically useful demonstration of the utility and promise of UAV platforms for Earth science and applications observations. Part of the demonstration involves getting approvals from the Federal Aviation Administration and the NASA airworthiness flight safety review board. ACES will employ the ALTUS II aircraft, built by General Atomics - Aeronautical Systems, Inc. Key science objectives simultaneously addressed by ACES are to: (1) investigate lightning-storm relationships, (2) study storm electrical budgets, and (3) provide Lightning Imaging Sensor validation. The ACES payload, already developed and flown on ALTUS, includes electrical, magnetic, and optical sensors to remotely characterize the lightning activity and the electrical environment within and around thunderstorms. ACES will contribute important electrical and optical measurements not available from other sources. Also, the high altitude vantage point of the UAV observing platform (up to 55,000 feet) offers a useful 'cloud-top' perspective. By taking advantage of its slow flight speed (70 to 100 knots), long endurance, and high altitude flight, the ALTUS will be flown near, and when possible, above (but never into) thunderstorms for long periods of time, allowing investigations to be conducted over entire storm life cycles. In addition, concurrent ground-based observations will enable the UAV measurements to be more completely interpreted and evaluated in the context of the thunderstorm structure, evolution, and environment.

Effect of Rare Earth Elements (Er, Ho) on Semi-Metallic Materials (ScN) in an Applied Electric Field

NASA Technical Reports Server (NTRS)

Kim, Hyunjung; Park, Yeonjoon; King, Glen C.; Lee, Kunik; Choi, Sang H.

2012-01-01

The development of materials and fabrication technology for field-controlled spectrally active optics is essential for applications such as membrane optics, filters for LIDARs, windows for sensors, telescopes, spectroscopes, cameras and flat-panel displays. The dopants of rare earth elements, in a host of optical systems, create a number of absorption and emission band structures and can easily be incorporated into many high quality crystalline and amorphous hosts. In wide band-gap semiconductors like ScN, the existing deep levels can capture or emit the mobile charges, and can be ionized with the loss or capture of the carriers which are the fundamental basis of concept for smart optic materials. The band gap shrinkage or splitting with dopants supports the possibility of this concept. In the present work, a semi-metallic material (ScN) was doped with rare earth elements (Er, Ho) and tested under an applied electric field to characterize spectral and refractive index shifts by either Stark or Zeeman Effect. These effects can be verified using the UV-Vis spectroscopy, the Hall Effect measurement and the ellipsometric spectroscopy. The optical band gaps of ScN doped with Er and doped with Ho were experimentally estimated as 2.33eV and 2.24eV ( 0.2eV) respectively. This is less than that of undoped ScN (2.5 0.2eV). The red-shifted absorption onset is a direct evidence for the decrease of band gap energy (Eg), and the broadening of valence band states is attributable to the doping cases. A decrease in refractive index with an applied field was observed as a small shift in absorption coefficient using a variable angle spectroscopic ellipsometer. In the presence of an electric field, mobile carriers are redistributed within the space charge region (SCR) to produce this electro-refractive effect. The shift in refractive index is also affected by the density and location of deep potential wells within the SCR. In addition, the microstructure change was observed by a TEM analysis. These results give an insight for future applications for the field-controlled spectrally active material systems.

Terahertz-bandwidth coherence measurements of a quantum dash laser in passive and active mode-locking operation.

PubMed

Martin, Eamonn; Watts, Regan; Bramerie, Laurent; Shen, Alexandre; Gariah, Harry; Blache, Fabrice; Lelarge, Francois; Barry, Liam

2012-12-01

This research carries out coherence measurements of a 42.7 GHz quantum dash (QDash) semiconductor laser when passively, electrically, and optically mode-locked. Coherence of the spectral lines from the mode-locked laser is determined by examining the radio frequency beat-tone linewidth as the mode spacing is increased up to 1.1 THz. Electric-field measurements of the QDash laser are also presented, from which a comparison between experimental results and accepted theory for coherence in passively mode-locked lasers has been performed.

Nanosecond electrical and optical pulses and self phase conjugation from photorefractive lithium niobate fibers and crystals

NASA Astrophysics Data System (ADS)

Kukhtarev, N.; Kukhtareva, T.; Curley, M.; Jaenisch, H. M.; Edwards, M. E.; Gu, M.; Zhou, Z.; Guo, R.

2007-09-01

We have observed nanosecond electrical and optical pulsations from photorefractive lithium-niobate optical fibers using CW green and blue low-power lasers. Fourier spectra of the pulsations have a maximum at ~900 MHz with peaks separated by ~30MHz. We consider free-space and fiber supported illumination of the fiber crystal. Strong nonlinear enhanced backscattering with phase conjugation was observed from bulk crystals and crystal fibers along the C-axis. Model of transformation of CW laser irradiation of ferroelectric crystals into periodic nanosecond electrical and optical pulsations is suggested. This model includes combinations of photorefractive, pyroelectric, piezoelectric, and photogalvanic mechanisms of the holographic grating formation and crystal electrical charging. Possible applications of these short photo-induced electrical pulses for modulation of holographic beam coupling, pulsed electrolysis, electrophoresis, focused electron beams, X-ray and neutron generation, and hand-held micro X-ray devices for localized oncology imaging and treatment based on our advanced sensor work are discussed.

Tandem junction amorphous silicon solar cells

DOEpatents

Hanak, Joseph J.

1981-01-01

An amorphous silicon solar cell has an active body with two or a series of layers of hydrogenated amorphous silicon arranged in a tandem stacked configuration with one optical path and electrically interconnected by a tunnel junction. The layers of hydrogenated amorphous silicon arranged in tandem configuration can have the same bandgap or differing bandgaps.

Imaging electric field dynamics with graphene optoelectronics

DOE PAGES

Horng, Jason; Balch, Halleh B.; McGuire, Allister F.; ...

2016-12-16

The use of electric fields for signalling and control in liquids is widespread, spanning bioelectric activity in cells to electrical manipulation of microstructures in lab-on-a-chip devices. However, an appropriate tool to resolve the spatio-temporal distribution of electric fields over a large dynamic range has yet to be developed. Here we present a label-free method to image local electric fields in real time and under ambient conditions. Our technique combines the unique gate-variable optical transitions of graphene with a critically coupled planar waveguide platform that enables highly sensitive detection of local electric fields with a voltage sensitivity of a few microvolts,more » a spatial resolution of tens of micrometres and a frequency response over tens of kilohertz. Our imaging platform enables parallel detection of electric fields over a large field of view and can be tailored to broad applications spanning lab-on-a-chip device engineering to analysis of bioelectric phenomena.« less

Imaging electric field dynamics with graphene optoelectronics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Horng, Jason; Balch, Halleh B.; McGuire, Allister F.

The use of electric fields for signalling and control in liquids is widespread, spanning bioelectric activity in cells to electrical manipulation of microstructures in lab-on-a-chip devices. However, an appropriate tool to resolve the spatio-temporal distribution of electric fields over a large dynamic range has yet to be developed. Here we present a label-free method to image local electric fields in real time and under ambient conditions. Our technique combines the unique gate-variable optical transitions of graphene with a critically coupled planar waveguide platform that enables highly sensitive detection of local electric fields with a voltage sensitivity of a few microvolts,more » a spatial resolution of tens of micrometres and a frequency response over tens of kilohertz. Our imaging platform enables parallel detection of electric fields over a large field of view and can be tailored to broad applications spanning lab-on-a-chip device engineering to analysis of bioelectric phenomena.« less

Advanced electric-field scanning probe lithography on molecular resist using active cantilever

NASA Astrophysics Data System (ADS)

Kaestner, Marcus; Aydogan, Cemal; Lipowicz, Hubert-Seweryn; Ivanov, Tzvetan; Lenk, Steve; Ahmad, Ahmad; Angelov, Tihomir; Reum, Alexander; Ishchuk, Valentyn; Atanasov, Ivaylo; Krivoshapkina, Yana; Hofer, Manuel; Holz, Mathias; Rangelow, Ivo W.

2015-03-01

The routine "on demand" fabrication of features smaller than 10 nm opens up new possibilities for the realization of many novel nanoelectronic, NEMS, optical and bio-nanotechnology-based devices. Based on the thermally actuated, piezoresistive cantilever technology we have developed a first prototype of a scanning probe lithography (SPL) platform able to image, inspect, align and pattern features down to single digit nano regime. The direct, mask-less patterning of molecular resists using active scanning probes represents a promising path circumventing the problems in today's radiation-based lithography. Here, we present examples of practical applications of the previously published electric field based, current-controlled scanning probe lithography on molecular glass resist calixarene by using the developed tabletop SPL system. We demonstrate the application of a step-and-repeat scanning probe lithography scheme including optical as well as AFM based alignment and navigation. In addition, sequential read-write cycle patterning combining positive and negative tone lithography is shown. We are presenting patterning over larger areas (80 x 80 μm) and feature the practical applicability of the lithographic processes.

Efficient modulation of optical and electrical properties of X-shaped thermally activated delayed fluorescence emitters by substitution.

PubMed

Fan, Jianzhong; Wang, Xin; Lin, Lili; Wang, Chuankui

2016-08-01

A series of X-shaped thermally activated delayed fluorescence (TADF) emitters are systematically studied by first-principles calculations. Effects of the cyano group adding to the acceptor unit and the hydroxyl group adding to the donor part on the optical and electrical properties are analyzed. It is found that both kinds of groups can efficiently increase the emission wavelength to realize full-color emission. Although they play different roles in modulating the energy level of frontier orbitals, the S-T energy gap, the reorganization energy and transfer integral for different molecules, they can efficiently increase the charge transfer rate and reduce the difference of electron transfer rate and hole transfer rate. These results indicate that these designed strategies are efficient to achieve balanced charge transfer rates and modulate emission colors. By analyzing the energy matching between the TADF emitters and three kinds of hosts, the emission spectra of the 3,5-bis(N-carbazolyl)benzene (mcp) and the absorption spectra of most TADF emitters have a large overlap, which provides helpful information in application of these TADF molecules.

A suite of optical fibre sensors for structural condition monitoring

NASA Astrophysics Data System (ADS)

Sun, T.; Grattan, K. T. V.; Carlton, J.

2015-05-01

This paper is to review the research activities at City University London in the development of a range of fibre Bragg grating (FBG)-based sensors, including strain, temperature, relative humidity, vibration and acoustic sensors, with an aim to meet the increasing demands from industry for structural condition monitoring. As a result, arrays of optical fibre sensors have been instrumented into various types of structures, including concrete, limestone, marine propellers, pantograph and electrical motors, allowing for both static and dynamic monitoring and thus enhanced structural reliability and integrity.

Thickness dependent optical and electrical properties of CdSe thin films

DOE Office of Scientific and Technical Information (OSTI.GOV)

Purohit, A., E-mail: anuradha.purohit34@gmail.com; Chander, S.; Nehra, S. P.

2016-05-06

The effect of thickness on the optical and electrical properties of CdSe thin films is investigated in this paper. The films of thickness 445 nm, 631 nm and 810 nm were deposited on glass and ITO coated glass substrates using thermal evaporation technique. The deposited thin films were thermally annealed in air atmosphere at temperature 100°C and were subjected to UV-Vis spectrophotometer and source meter for optical and electrical analysis respectively. The absorption coefficient is observed to increase with photon energy and found maximum in higher photon energy region. The extinction coefficient and refractive index are also calculated. The electrical analysis shows thatmore » the electrical resistivity is observed to be decreased with thickness.« less

Macroscopic response in active nonlinear photonic crystals.

PubMed

Alagappan, Gandhi; John, Sajeev; Li, Er Ping

2013-09-15

We derive macroscopic equations of motion for the slowly varying electric field amplitude in three-dimensional active nonlinear optical nanostructures. We show that the microscopic Maxwell equations and polarization dynamics can be simplified to a macroscopic one-dimensional problem in the direction of group velocity. For a three-level active material, we derive the steady-state equations for normal mode frequency, threshold pumping, nonlinear Bloch mode amplitude, and lasing in photonic crystals. Our analytical results accurately recapture the results of exact numerical methods.

Relative position of the atrioventricular canal determines the electrical activation of developing reptile ventricles.

PubMed

Gregorovicova, Martina; Sedmera, David; Jensen, Bjarke

2018-04-19

Squamate reptiles appear to lack the specialized His/Purkinje system that enables the cardiac ventricle to be activated from apex to base as in mammals and birds. Instead, activation may simply spread from where the atrioventricular canal connects to the base. Gja5 , which encodes Cx40 that allows fast impulse propagation, was expressed throughout the ventricles of developing anole lizards. Activation was optically recorded in developing corn snake and central bearded dragon. Early embryonic ventricles were broad in shape, and activation propagated from the base to the right. Elongated ventricles of later stages were activated from base to apex. Before hatching, the snake ventricle developed a cranial extension on the left and activation now propagated from the base to the caudal apex and the cranial extension. In squamate reptiles, the pattern of electrical activation of the cardiac ventricle is dependent the position of the atrioventricular canal and the shape of the ventricle. © 2018. Published by The Company of Biologists Ltd.

Monitoring of interaction of low-frequency electric field with biological tissues upon optical clearing with optical coherence tomography.

PubMed

Peña, Adrián F; Doronin, Alexander; Tuchin, Valery V; Meglinski, Igor

2014-08-01

The influence of a low-frequency electric field applied to soft biological tissues ex vivo at normal conditions and upon the topical application of optical clearing agents has been studied by optical coherence tomography (OCT). The electro-kinetic response of tissues has been observed and quantitatively evaluated by the double correlation OCT approach, utilizing consistent application of an adaptive Wiener filtering and Fourier domain correlation algorithm. The results show that fluctuations, induced by the electric field within the biological tissues are exponentially increased in time. We demonstrate that in comparison to impedance measurements and the mapping of the temperature profile at the surface of the tissue samples, the double correlation OCT approach is much more sensitive to the changes associated with the tissues' electro-kinetic response. We also found that topical application of the optical clearing agent reduces the tissues' electro-kinetic response and is cooling the tissue, thus reducing the temperature induced by the electric current by a few degrees. We anticipate that dcOCT approach can find a new application in bioelectrical impedance analysis and monitoring of the electric properties of biological tissues, including the resistivity of high water content tissues and its variations.

Tunable electronic, electrical and optical properties of graphene oxide sheets by ion irradiation

NASA Astrophysics Data System (ADS)

Jayalakshmi, G.; Saravanan, K.; Panigrahi, B. K.; Sundaravel, B.; Gupta, Mukul

2018-05-01

The tunable electronic, electrical and optical properties of graphene oxide (GO) sheets were investigated using a controlled reduction by 500 keV Ar+-ion irradiation. The carbon to oxygen ratio of the GO sheets upon the ion beam reduction has been estimated using resonant Rutherford backscattering spectrometry analyses and its effect on the electrical and optical properties of GO sheets has been studied using sheet resistance measurements and photoluminescence (PL) measurements. The restoration of sp 2-hybridized carbon atoms within the sp 3 matrix is found to be increases with increasing the Ar+-ion fluences as evident from Fourier transform infrared, and x-ray absorption near-edge structure measurements. The decrease in the number of disorder-induced local density of states (LDOSs) within the π-π* gap upon the reduction causes the shifting of PL emission from near infra-red to blue region and decreases the sheet resistance. The improved electrical and optical properties of GO sheets were correlated to the decrease in the number of LDOSs within the π-π* gap. Our experimental investigations suggest ion beam irradiation is one of an effective approaches to reduce GO to RGO and to tailor its electronic, electrical and optical properties.

Tunable electronic, electrical and optical properties of graphene oxide sheets by ion irradiation.

PubMed

Jayalakshmi, G; Saravanan, K; Panigrahi, B K; Sundaravel, B; Gupta, Mukul

2018-05-04

The tunable electronic, electrical and optical properties of graphene oxide (GO) sheets were investigated using a controlled reduction by 500 keV Ar + -ion irradiation. The carbon to oxygen ratio of the GO sheets upon the ion beam reduction has been estimated using resonant Rutherford backscattering spectrometry analyses and its effect on the electrical and optical properties of GO sheets has been studied using sheet resistance measurements and photoluminescence (PL) measurements. The restoration of sp 2 -hybridized carbon atoms within the sp 3 matrix is found to be increases with increasing the Ar + -ion fluences as evident from Fourier transform infrared, and x-ray absorption near-edge structure measurements. The decrease in the number of disorder-induced local density of states (LDOSs) within the π-π* gap upon the reduction causes the shifting of PL emission from near infra-red to blue region and decreases the sheet resistance. The improved electrical and optical properties of GO sheets were correlated to the decrease in the number of LDOSs within the π-π* gap. Our experimental investigations suggest ion beam irradiation is one of an effective approaches to reduce GO to RGO and to tailor its electronic, electrical and optical properties.

Lightning vulnerability of fiber-optic cables.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Martinez, Leonard E.; Caldwell, Michele

2008-06-01

One reason to use optical fibers to transmit data is for isolation from unintended electrical energy. Using fiber optics in an application where the fiber cable/system penetrates the aperture of a grounded enclosure serves two purposes: first, it allows for control signals to be transmitted where they are required, and second, the insulating properties of the fiber system help to electrically isolate the fiber terminations on the inside of the grounded enclosure. A fundamental question is whether fiber optic cables can allow electrical energy to pass through a grounded enclosure, with a lightning strike representing an extreme but very importantmore » case. A DC test bed capable of producing voltages up to 200 kV was used to characterize electrical properties of a variety of fiber optic cable samples. Leakage current in the samples were measured with a micro-Ammeter. In addition to the leakage current measurements, samples were also tested to DC voltage breakdown. After the fiber optic cables samples were tested with DC methods, they were tested under representative lightning conditions at the Sandia Lightning Simulator (SLS). Simulated lightning currents of 30 kA and 200 kA were selected for this test series. This paper documents measurement methods and test results for DC high voltage and simulated lightning tests performed at the Sandia Lightning Simulator on fiber optic cables. The tests performed at the SLS evaluated whether electrical energy can be conducted inside or along the surface of a fiber optic cable into a grounded enclosure under representative lightning conditions.« less

Effect of Variable Oxidation States of Vanadium on the Structural, Optical, and Dielectric Properties of B2O3-Li2O-ZnO-V2O5 Glasses.

PubMed

Arya, S K; Danewalia, S S; Arora, Manju; Singh, K

2016-12-01

In the present study, the effect of variable vanadium oxidation states on the structural, optical, and dielectric properties of vanadium oxide containing lithium borate glasses has been investigated. Electron paramagnetic resonance studies indicate that vanadium in these glasses is mostly in the V 4+ state, having a tetragonal symmetry. As the glass composition of V 2 O 5 increases, tetragonality also increases at the cost of octahedral symmetry. The photoluminescence (PL) spectra of these glasses are dominated by zinc oxide transition, whereas the peaks pertaining to the vanadyl group are not visible in the PL spectra. The optical absorption spectra show a single wide absorption band, which is attributed to V 4+ ions in these glasses. The ac conductivity of the glasses increases with an increase in vanadium content. The highest electrical conductivity observed is ∼10 -5 S cm -1 at 250 °C for the glass with 2.5 mol % V 2 O 5 . Electrical conductivity is dominated by electron conduction, as indicated by the activation energy calculation.

Diagnostics of pre-breakdown light emission in a helium coplanar barrier discharge: the presence of neutral bremsstrahlung

NASA Astrophysics Data System (ADS)

Navrátil, Zdeněk; Morávek, Tomáš; Ráheľ, Jozef; Čech, Jan; Lalinský, Ondřej; Trunec, David

2017-05-01

Weak light emission (˜10-3 of active discharge signal; average count rate ˜ 1 photon s-1 nm-1) associated with surface charge relaxation during the dark phase of a helium diffuse coplanar barrier discharge was studied by optical emission spectroscopy, using a technique of phase-resolved single photon counting. The optical emission spectra of the dark phase contained luminescent bands of the dielectrics used (Al2O3, AlN) and spectral lines from the gas constituents (OH*, {{{N}}}2* , {{{N}}}2+* , He*, He{}2* , O*). During the charge relaxation event, a broad continuum appeared in the optical emission spectra, consisting of bremsstrahlung radiation and amplified luminescence of the dielectric barrier. The analysis presented suggests that the bremsstrahlung radiation originated from slow electrons colliding with neutral helium atoms. The fitting procedure we developed reproduced well the observed shape of the continuum. Moreover, it provided a method for the determination of electric field strength in the discharge during this particular phase. The electric field reached 1 kV cm-1 during the charge relaxation event.

Filling in the voids of electrospun hydroxypropyl cellulose network: Dielectric investigations

NASA Astrophysics Data System (ADS)

Maximean, Doina Manaila; Danila, Octavian; Ganea, Constantin Paul; Almeida, Pedro L.

2018-04-01

Here we describe an organic electro-optic device, obtained using electrospun hydroxypropyl cellulose (HPC) polymer fibres and nematic liquid crystals (LC). Its working mechanism is similar to that of a classic polymer-dispersed liquid crystal (PDLC) device. The scanning electron microscopy of the HPC deposited fibres shows a mat of fibres with diameters in the nano and micron size range. Dielectric spectroscopy measurements allow the determination of the dependence of the dielectric constant and electric energy loss on frequency and temperature as well as the determination of the activation energy. The electro-optic study shows a very good optical transmission curve, with an "on"-"off" switching voltage of less than 1V/μ m.

Purcell effect for active tuning of light scattering from semiconductor optical antennas.

PubMed

Holsteen, Aaron L; Raza, Søren; Fan, Pengyu; Kik, Pieter G; Brongersma, Mark L

2017-12-15

Subwavelength, high-refractive index semiconductor nanostructures support optical resonances that endow them with valuable antenna functions. Control over the intrinsic properties, including their complex refractive index, size, and geometry, has been used to manipulate fundamental light absorption, scattering, and emission processes in nanostructured optoelectronic devices. In this study, we harness the electric and magnetic resonances of such antennas to achieve a very strong dependence of the optical properties on the external environment. Specifically, we illustrate how the resonant scattering wavelength of single silicon nanowires is tunable across the entire visible spectrum by simply moving the height of the nanowires above a metallic mirror. We apply this concept by using a nanoelectromechanical platform to demonstrate active tuning. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

Closed-loop optical neural stimulation based on a 32-channel low-noise recording system with online spike sorting

NASA Astrophysics Data System (ADS)

Nguyen, T. K. T.; Navratilova, Z.; Cabral, H.; Wang, L.; Gielen, G.; Battaglia, F. P.; Bartic, C.

2014-08-01

Objective. Closed-loop operation of neuro-electronic systems is desirable for both scientific and clinical (neuroprosthesis) applications. Integrating optical stimulation with recording capability further enhances the selectivity of neural stimulation. We have developed a system enabling the local delivery of optical stimuli and the simultaneous electrical measuring of the neural activities in a closed-loop approach. Approach. The signal analysis is performed online through the implementation of a template matching algorithm. The system performance is demonstrated with the recorded data and in awake rats. Main results. Specifically, the neural activities are simultaneously recorded, detected, classified online (through spike sorting) from 32 channels, and used to trigger a light emitting diode light source using generated TTL signals. Significance. A total processing time of 8 ms is achieved, suitable for optogenetic studies of brain mechanisms online.

Actively Q-switched, thulium-holmium-codoped fiber laser incorporating a silicon-based, variable-optical-attenuator-based Q switch.

PubMed

Jung, Minwan; Han Lee, Ju

2013-04-20

An actively Q-switched thulium-holmium-codoped fiber laser incorporating an Si-based variable optical attenuator (VOA) is experimentally demonstrated. It has been shown that an Si-based VOA with a response time of hundreds of nanoseconds can be used as a cost-effective 2 μm Q switch due to its extremely wide operating bandwidth from 1.5 to 2 μm, and low electrical power consumption. In our study, the laser's slope efficiency was measured to be ~17% at an operating wavelength of 1.89 μm. The repetition rate tuning range was from 20 to 80 kHz, which was limited by the optical damage threshold and the response time. The minimum temporal pulsewidth was measured to be ~184 ns at a modulation frequency of 20 kHz, and the corresponding maximum peak power was ~10 W.

Electrical crosstalk-coupling measurement and analysis for digital closed loop fibre optic gyro

NASA Astrophysics Data System (ADS)

Jin, Jing; Tian, Hai-Ting; Pan, Xiong; Song, Ning-Fang

2010-03-01

The phase modulation and the closed-loop controller can generate electrical crosstalk-coupling in digital closed-loop fibre optic gyro. Four electrical cross-coupling paths are verified by the open-loop testing approach. It is found the variation of ramp amplitude will lead to the alternation of gyro bias. The amplitude and the phase parameters of the electrical crosstalk signal are measured by lock-in amplifier, and the variation of gyro bias is confirmed to be caused by the alternation of phase according to the amplitude of the ramp. A digital closed-loop fibre optic gyro electrical crosstalk-coupling model is built by approximating the electrical cross-coupling paths as a proportion and integration segment. The results of simulation and experiment show that the modulation signal electrical crosstalk-coupling can cause the dead zone of the gyro when a small angular velocity is inputted, and it could also lead to a periodic vibration of the bias error of the gyro when a large angular velocity is inputted.

Nanosecond liquid crystalline optical modulator

DOE Office of Scientific and Technical Information (OSTI.GOV)

Borshch, Volodymyr; Shiyanovskii, Sergij V.; Lavrentovich, Oleg D.

2016-07-26

An optical modulator includes a liquid crystal cell containing liquid crystal material having liquid crystal molecules oriented along a quiescent director direction in the unbiased state, and a voltage source configured to apply an electric field to the liquid crystal material wherein the direction of the applied electric field does not cause the quiescent director direction to change. An optical source is arranged to transmit light through or reflect light off the liquid crystal cell with the light passing through the liquid crystal material at an angle effective to undergo phase retardation in response to the voltage source applying themore » electric field. The liquid crystal material may have negative dielectric anisotropy, and the voltage source configured to apply an electric field to the liquid crystal material whose electric field vector is transverse to the quiescent director direction. Alternatively, the liquid crystal material may have positive dielectric anisotropy and the voltage source configured to apply an electric field to the liquid crystal material whose electric field vector is parallel with the quiescent director direction.« less

Plasmonic transparent conductors

NASA Astrophysics Data System (ADS)

Liapis, Andreas C.; Sfeir, Matthew Y.; Black, Charles T.

2016-09-01

Many of today's technological applications, such as solar cells, light-emitting diodes, displays, and touch screens, require materials that are simultaneously optically transparent and electrically conducting. Here we explore transparent conductors based on the excitation of surface plasmons in nanostructured metal films. We measure both the optical and electrical properties of films perforated with nanometer-scale features and optimize the design parameters in order to maximize optical transmission without sacrificing electrical conductivity. We demonstrate that plasmonic transparent conductors can out-perform indium tin oxide in terms of both their transparency and their conductivity.

Fiber optic and laser sensors IV; Proceedings of the Meeting, Cambridge, MA, Sept. 22-24, 1986

NASA Technical Reports Server (NTRS)

De Paula, Ramon P. (Editor); Udd, Eric (Editor)

1987-01-01

The conference presents papers on industrial uses of fiber optic sensors, point and distributed polarimetric optical fiber sensors, fiber optic electric field sensor technology, micromachined resonant structures, single-mode fibers for sensing applications, and measurement techniques for magnetic field gradient detection. Consideration is also given to electric field meter and temperature measurement techniques for the power industry, the calibration of high-temperature fiber-optic microbend pressure transducers, and interferometric sensors for dc measurands. Other topics include the recognition of colors and collision avoidance in robotics using optical fiber sensors, the loss compensation of intensity-modulating fiber-optic sensors, and an embedded optical fiber strain tensor for composite structure applications.

Broadband radiometer

DOEpatents

Cannon, Theodore W.

1994-01-01

A broadband radiometer including (a) an optical integrating sphere having a enerally spherical integrating chamber and an entry port for receiving light (e.g., having visible and ultraviolet fractions), (b) a first optical radiation detector for receiving light from the sphere and producing an electrical output signal corresponding to broadband radiation, (c) a second optical radiation detector for receiving light from the sphere and producing an electrical output signal corresponding to a predetermined wavelength fraction of the broadband radiation, and (d) an output for producing an electrical signal which is proportional to the difference between the two electrical output signals. The radiometer is very useful, for example, in measuring the absolute amount of ultraviolet light present in a given light sample.

Broadband radiometer

DOEpatents

Cannon, T.W.

1994-07-26

A broadband radiometer is disclosed including (a) an optical integrating sphere having generally spherical integrating chamber and an entry port for receiving light (e.g., having visible and ultraviolet fractions), (b) a first optical radiation detector for receiving light from the sphere and producing an electrical output signal corresponding to broadband radiation, (c) a second optical radiation detector for receiving light from the sphere and producing an electrical output signal corresponding to a predetermined wavelength fraction of the broadband radiation, and (d) an output for producing an electrical signal which is proportional to the difference between the two electrical output signals. The radiometer is very useful, for example, in measuring the absolute amount of ultraviolet light present in a given light sample. 8 figs.

Electro-optic Lightning Detector

NASA Technical Reports Server (NTRS)

Koshak, William J.; Solakiewicz, Richard J.

1996-01-01

The design, alignment, calibration, and field deployment of a solid-state lightning detector is described. The primary sensing component of the detector is a potassium dihydrogen phosphate (KDP) electro-optic crystal that is attached in series to a flat plate aluminum antenna; the antenna is exposed to the ambient thundercloud electric field. A semiconductor laser diode (lambda = 685 nm), polarizing optics, and the crystal are arranged in a Pockels cell configuration. Lightning-caused electric field changes are related to small changes in the transmission of laser light through the optical cell. Several hundred lightning electric field change excursions were recorded during five thunderstorms that occurred in the summer of 1998 at the NASA Marshall Space Flight Center (MSFC) in northern Alabama.

Electro-Optic Lightning Detector

NASA Technical Reports Server (NTRS)

Koshak, Willliam; Solakiewicz, Richard

1998-01-01

The design, alignment, calibration, and field deployment of a solid-state lightning detector is described. The primary sensing component of the detector is a potassium dihydrogen phosphate (KDP) electro-optic crystal that is attached in series to a flat plate aluminum antenna; the antenna is exposed to the ambient thundercloud electric field. A semiconductor laser diode (lambda = 685 nm), polarizing optics, and the crystal are arranged in a Pockels cell configuration. Lightning-caused electric field changes are then related to small changes in the transmission of laser light through the optical cell. Several hundred lightning electric field change excursions were recorded during 4 thunderstorms that occurred in the summer of 1998 at the NASA Marshall Space Flight Center (MSFC) in Northern Alabama.

Electro-Optic Lighting Detector

NASA Technical Reports Server (NTRS)

Koshak, William J.; Solakiewicz, Richard J.

1999-01-01

The design, alignment, calibration, and field deployment of a solid-state lightning detector is described. The primary sensing component of the detector is a potassium dihydrogen phosphate electro-optic crystal that is attached in series to a flat-plate aluminum antenna; the antenna is exposed to the ambient thundercloud electric field. A semiconductor laser diode (lambda = 685 nm), polarizing optics, and the crystal are arranged in a Pockels cell configuration. Lightning-caused electric field changes are related to small changes in the transmission of laser light through the optical cell. Several hundred lightning electric field change excursions were recorded during five thunderstorms that occurred in the summer of 1998 at the NASA Marshall Space Flight Center in northern Alabama.

Local domains of motor cortical activity revealed by fiber-optic calcium recordings in behaving nonhuman primates.

PubMed

Adelsberger, Helmuth; Zainos, Antonio; Alvarez, Manuel; Romo, Ranulfo; Konnerth, Arthur

2014-01-07

Brain mapping experiments involving electrical microstimulation indicate that the primary motor cortex (M1) directly regulates muscle contraction and thereby controls specific movements. Possibly, M1 contains a small circuit "map" of the body that is formed by discrete local networks that code for specific movements. Alternatively, movements may be controlled by distributed, larger-scale overlapping circuits. Because of technical limitations, it remained unclear how movement-determining circuits are organized in M1. Here we introduce a method that allows the functional mapping of small local neuronal circuits in awake behaving nonhuman primates. For this purpose, we combined optic-fiber-based calcium recordings of neuronal activity and cortical microstimulation. The method requires targeted bulk loading of synthetic calcium indicators (e.g., OGB-1 AM) for the staining of neuronal microdomains. The tip of a thin (200 µm) optical fiber can detect the coherent activity of a small cluster of neurons, but is insensitive to the asynchronous activity of individual cells. By combining such optical recordings with microstimulation at two well-separated sites of M1, we demonstrate that local cortical activity was tightly associated with distinct and stereotypical simple movements. Increasing stimulation intensity increased both the amplitude of the movements and the level of neuronal activity. Importantly, the activity remained local, without invading the recording domain of the second optical fiber. Furthermore, there was clear response specificity at the two recording sites in a trained behavioral task. Thus, the results provide support for movement control in M1 by local neuronal clusters that are organized in discrete cortical domains.

Optically isolated signal coupler with linear response

DOEpatents

Kronberg, James W.

1994-01-01

An optocoupler for isolating electrical signals that translates an electrical input signal linearly to an electrical output signal. The optocoupler comprises a light emitter, a light receiver, and a light transmitting medium. The light emitter, preferably a blue, silicon carbide LED, is of the type that provides linear, electro-optical conversion of electrical signals within a narrow wavelength range. Correspondingly, the light receiver, which converts light signals to electrical signals and is preferably a cadmium sulfide photoconductor, is linearly responsive to light signals within substantially the same wavelength range as the blue LED.

High-accurate optical vector analysis based on optical single-sideband modulation

NASA Astrophysics Data System (ADS)

Xue, Min; Pan, Shilong

2016-11-01

Most of the efforts devoted to the area of optical communications were on the improvement of the optical spectral efficiency. Varies innovative optical devices are thus developed to finely manipulate the optical spectrum. Knowing the spectral responses of these devices, including the magnitude, phase and polarization responses, is of great importance for their fabrication and application. To achieve high-resolution characterization, optical vector analyzers (OVAs) based on optical single-sideband (OSSB) modulation have been proposed and developed. Benefiting from the mature and highresolution microwave technologies, the OSSB-based OVA can potentially achieve a resolution of sub-Hz. However, the accuracy is restricted by the measurement errors induced by the unwanted first-order sideband and the high-order sidebands in the OSSB signal, since electrical-to-optical conversion and optical-to-electrical conversion are essentially required to achieve high-resolution frequency sweeping and extract the magnitude and phase information in the electrical domain. Recently, great efforts have been devoted to improve the accuracy of the OSSB-based OVA. In this paper, the influence of the unwanted-sideband induced measurement errors and techniques for implementing high-accurate OSSB-based OVAs are discussed.

Mathematical model of optical signals emitted by electrical discharges occuring in electroinsulating oil

NASA Astrophysics Data System (ADS)

Kozioł, Michał

2017-10-01

The article presents a parametric model describing the registered distributions spectrum of optical radiation emitted by electrical discharges generated in the systems: the needle- needle, the needleplate and in the system for surface discharges. Generation of electrical discharges and registration of the emitted radiation was carried out in three different electrical insulating oils: fabric new, operated (used) and operated with air bubbles. For registration of optical spectra in the range of ultraviolet, visible and near infrared a high resolution spectrophotometer was. The proposed mathematical model was developed in a regression procedure using gauss-sigmoid type function. The dependent variable was the intensity of the recorded optical signals. In order to estimate the optimal parameters of the model an evolutionary algorithm was used. The optimization procedure was performed in Matlab environment. For determination of the matching quality of theoretical parameters of the regression function to the empirical data determination coefficient R2 was applied.

Electrical and optical performance of transparent conducting oxide films deposited by electrostatic spray assisted vapour deposition.

PubMed

Hou, Xianghui; Choy, Kwang-Leong; Liu, Jun-Peng

2011-09-01

Transparent conducting oxide (TCO) films have the remarkable combination of high electrical conductivity and optical transparency. There is always a strong motivation to produce TCO films with good performance at low cost. Electrostatic Spray Assisted Vapor Deposition (ESAVD), as a variant of chemical vapour deposition (CVD), is a non-vacuum and low-cost deposition method. Several types of TCO films have been deposited using ESAVD process, including indium tin oxide (ITO), antimony-doped tin oxide (ATO), and fluorine doped tin oxide (FTO). This paper reports the electrical and optical properties of TCO films produced by ESAVD methods, as well as the effects of post treatment by plasma hydrogenation on these TCO films. The possible mechanisms involved during plasma hydrogenation of TCO films are also discussed. Reduction and etching effect during plasma hydrogenation are the most important factors which determine the optical and electrical performance of TCO films.

Electrical and optical properties of Ar/NH{sub 3} atmospheric pressure plasma jet

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Zheng-Shi, E-mail: changzhsh1984@163.com, E-mail: gjzhang@xjtu.edu.cn; Yao, Cong-Wei; Chen, Si-Le

Inspired by the Penning effect, we obtain a glow-like plasma jet by mixing ammonia (NH{sub 3}) into argon (Ar) gas under atmospheric pressure. The basic electrical and optical properties of an atmospheric pressure plasma jet (APPJ) are investigated. It can be seen that the discharge mode transforms from filamentary to glow-like when a little ammonia is added into the pure argon. The electrical and optical analyses contribute to the explanation of this phenomenon. The discharge mode, power, and current density are analyzed to understand the electrical behavior of the APPJ. Meanwhile, the discharge images, APPJ's length, and the components ofmore » plasma are also obtained to express its optical characteristics. Finally, we diagnose several parameters, such as gas temperature, electron temperature, and density, as well as the density number of metastable argon atoms of Ar/NH{sub 3} APPJ to help judge the usability in its applications.« less

Electrical and optical analyses of tandem organic light-emitting diodes with organic charge-generation layer

NASA Astrophysics Data System (ADS)

Kim, Bong Sung; Chae, Heeyeop; Chung, Ho Kyoon; Cho, Sung Min

2018-06-01

The electrical and optical properties of tandem organic light-emitting diodes (OLEDs), in which a fluorescent and phosphorescent emitting units are connected by an organic charge-generation layer (CGL), were experimentally analyzed. To investigate the internal properties of the tandem OLEDs, we fabricated and compared two single, two homo-tandem, and two hetero-tandem OLEDs using the fluorescent and phosphorescent units. From the experimental results of the OLEDs obtained at the same current density, the voltage across the CGL as well as the individual emission spectra and luminance of each unit of tandem OLEDs were obtained and compared with the theoretical simulation results. The analysis method proposed in this study can be utilized as a method to verify the accuracy of optical or electrical computer simulation of tandem OLED and it will be useful to understand the overall electrical and optical characteristics of tandem OLEDs.

Optical properties in GaAs/AlGaAs semiparabolic quantum wells by the finite difference method: Combined effects of electric field and magnetic field

NASA Astrophysics Data System (ADS)

Yan, Ru-Yu; Tang, Jian; Zhang, Zhi-Hai; Yuan, Jian-Hui

2018-05-01

In the present work, the optical properties of GaAs/AlGaAs semiparabolic quantum wells (QWs) are studied under the effect of applied electric field and magnetic field by using the compact-density-matrix method. The energy eigenvalues and their corresponding eigenfunctions of the system are calculated by using the differential method. Simultaneously, the nonlinear optical rectification (OR) and optical absorption coefficients (OACs) are investigated, which are modulated by the applied electric field and magnetic field. It is found that the position and the magnitude of the resonant peaks of the nonlinear OR and OACs can depend strongly on the applied electric field, magnetic field and confined potential frequencies. This gives a new way to control the device applications based on the intersubband transitions of electrons in this system.

Emerging Carbon and Post-Carbon Nanomaterial Inks for Printed Electronics.

PubMed

Secor, Ethan B; Hersam, Mark C

2015-02-19

Carbon and post-carbon nanomaterials present desirable electrical, optical, chemical, and mechanical attributes for printed electronics, offering low-cost, large-area functionality on flexible substrates. In this Perspective, recent developments in carbon nanomaterial inks are highlighted. Monodisperse semiconducting single-walled carbon nanotubes compatible with inkjet and aerosol jet printing are ideal channels for thin-film transistors, while inkjet, gravure, and screen-printable graphene-based inks are better-suited for electrodes and interconnects. Despite the high performance achieved in prototype devices, additional effort is required to address materials integration issues encountered in more complex systems. In this regard, post-carbon nanomaterial inks (e.g., electrically insulating boron nitride and optically active transition-metal dichalcogenides) present promising opportunities. Finally, emerging work to extend these nanomaterial inks to three-dimensional printing provides a path toward nonplanar devices. Overall, the superlative properties of these materials, coupled with versatile assembly by printing techniques, offer a powerful platform for next-generation printed electronics.

Optically tunable Quincke rotation of a nanometer-thin oblate spheroid

NASA Astrophysics Data System (ADS)

Gu, Yu; Zeng, Haibo

2017-08-01

Ever since the discovery of Quincke rotation (spontaneous rotation of a particle in fluid under a dc electric field) more than 100 years ago [G. Quincke, Ann. Phys. (Leipzig) 295, 417 (1896), 10.1002/andp.18962951102], the strength of the dc field has been the only external parameter to actively tune the rotation speed. In this paper we theoretically propose an optically tunable Quincke rotor exploiting the photoconductivity of a semiconducting nanometer-thin oblate spheroid. A full analysis of the instability of the Quincke rotation reveals that, unlike a prolate spheroid, no bistability is possible in such a dynamical system. In addition, the required material property and the strength of the dc electric field needed to realize the rotation are also elucidated. It is also predicted that light can be used to tune the spinning speed or simply turn on and off the Quincke rotation very effectively.

Investigation of structural, optical and electrical properties of Co3O4 nanoparticles

NASA Astrophysics Data System (ADS)

Bhargava, Richa; Khan, Shakeel; Ahmad, Naseem; Ansari, Mohd Mohsin Nizam

2018-05-01

In the current work, we report the synthesis of Cobalt oxide (Co3O4) NPs (NPs) by co-precipitation method. The structural analysis was confirmed by using X-ray diffractometer (XRD) which shows that the Co3O4 NPs have cubic phase. The average crystallite size and the lattice parameter were calculated for Co3O4 NPs. The functional groups of the as-synthesized sample were examined by Fourier transform infrared spectroscopy (FTIR). The optical band gap of Co3O4 NPs was estimated by using UV diffuse reflectance spectroscopy and the Band gap was evaluated by using Tauc relation. The temperature dependence of dielectric constant and dielectric loss were studied over a range of temperature 50-300 °C. The DC electrical resistivity of Co3O4 NPs shows a semiconducting behaviour and the value of activation energy was calculated by using Arrhenius equation.

Optical tolerances for the PICTURE-C mission: error budget for electric field conjugation, beam walk, surface scatter, and polarization aberration

NASA Astrophysics Data System (ADS)

Mendillo, Christopher B.; Howe, Glenn A.; Hewawasam, Kuravi; Martel, Jason; Finn, Susanna C.; Cook, Timothy A.; Chakrabarti, Supriya

2017-09-01

The Planetary Imaging Concept Testbed Using a Recoverable Experiment - Coronagraph (PICTURE-C) mission will directly image debris disks and exozodiacal dust around nearby stars from a high-altitude balloon using a vector vortex coronagraph. Four leakage sources owing to the optical fabrication tolerances and optical coatings are: electric field conjugation (EFC) residuals, beam walk on the secondary and tertiary mirrors, optical surface scattering, and polarization aberration. Simulations and analysis of these four leakage sources for the PICTUREC optical design are presented here.

Fiber-Optic Distribution Of Pulsed Power To Multiple Sensors

NASA Technical Reports Server (NTRS)

Kirkham, Harold

1996-01-01

Optoelectronic systems designed according to time-sharing scheme distribute optical power to multiple integrated-circuit-based sensors in fiber-optic networks. Networks combine flexibility of electronic sensing circuits with advantage of electrical isolation afforded by use of optical fibers instead of electrical conductors to transmit both signals and power. Fiber optics resist corrosion and immune to electromagnetic interference. Sensor networks of this type useful in variety of applications; for example, in monitoring strains in aircraft, buildings, and bridges, and in monitoring and controlling shapes of flexible structures.

Wavelength-tunable optical ring resonators

DOEpatents

Watts, Michael R [Albuquerque, NM; Trotter, Douglas C [Albuquerque, NM; Young, Ralph W [Albuquerque, NM; Nielson, Gregory N [Albuquerque, NM

2009-11-10

Optical ring resonator devices are disclosed that can be used for optical filtering, modulation or switching, or for use as photodetectors or sensors. These devices can be formed as microdisk ring resonators, or as open-ring resonators with an optical waveguide having a width that varies adiabatically. Electrical and mechanical connections to the open-ring resonators are made near a maximum width of the optical waveguide to minimize losses and thereby provide a high resonator Q. The ring resonators can be tuned using an integral electrical heater, or an integral semiconductor junction.

Wavelength-tunable optical ring resonators

DOEpatents

Watts, Michael R [Albuquerque, NM; Trotter, Douglas C [Albuquerque, NM; Young, Ralph W [Albuquerque, NM; Nielson, Gregory N [Albuquerque, NM

2011-07-19

Optical ring resonator devices are disclosed that can be used for optical filtering, modulation or switching, or for use as photodetectors or sensors. These devices can be formed as microdisk ring resonators, or as open-ring resonators with an optical waveguide having a width that varies adiabatically. Electrical and mechanical connections to the open-ring resonators are made near a maximum width of the optical waveguide to minimize losses and thereby provide a high resonator Q. The ring resonators can be tuned using an integral electrical heater, or an integral semiconductor junction.

WDM package enabling high-bandwidth optical intrasystem interconnects for high-performance computer systems

NASA Astrophysics Data System (ADS)

Schrage, J.; Soenmez, Y.; Happel, T.; Gubler, U.; Lukowicz, P.; Mrozynski, G.

2006-02-01

From long haul, metro access and intersystem links the trend goes to applying optical interconnection technology at increasingly shorter distances. Intrasystem interconnects such as data busses between microprocessors and memory blocks are still based on copper interconnects today. This causes a bottleneck in computer systems since the achievable bandwidth of electrical interconnects is limited through the underlying physical properties. Approaches to solve this problem by embedding optical multimode polymer waveguides into the board (electro-optical circuit board technology, EOCB) have been reported earlier. The principle feasibility of optical interconnection technology in chip-to-chip applications has been validated in a number of projects. For reasons of cost considerations waveguides with large cross sections are used in order to relax alignment requirements and to allow automatic placement and assembly without any active alignment of components necessary. On the other hand the bandwidth of these highly multimodal waveguides is restricted due to mode dispersion. The advance of WDM technology towards intrasystem applications will provide sufficiently high bandwidth which is required for future high-performance computer systems: Assuming that, for example, 8 wavelength-channels with 12Gbps (SDR1) each are given, then optical on-board interconnects with data rates a magnitude higher than the data rates of electrical interconnects for distances typically found at today's computer boards and backplanes can be realized. The data rate will be twice as much, if DDR2 technology is considered towards the optical signals as well. In this paper we discuss an approach for a hybrid integrated optoelectronic WDM package which might enable the application of WDM technology to EOCB.

Optical properties of an elliptic quantum ring: Eccentricity and electric field effects

NASA Astrophysics Data System (ADS)

Bejan, Doina; Stan, Cristina; Niculescu, Ecaterina C.

2018-04-01

We have theoretically studied the electronic and optical properties of a GaAs/AlGaAs elliptic quantum ring under in-plane electric field. The effects of an eccentric internal barrier -placed along the electric field direction, chosen as x-axis- and incident light polarization are particularly taken into account. The one-electron energy spectrum and wave functions are found using the adiabatic approximation and the finite element method within the effective-mass model. We show that it is possible to repair the structural distortion by applying an appropriate in-plane electric field, and the compensation is almost complete for all electronic states under study. For both concentric and eccentric quantum ring the intraband optical properties are very sensitive to the electric field and probe laser polarization. As expected, in the systems with eccentricity distortions the energy spectrum, as well as the optical response, strongly depends on the direction of the externally applied electric field, an effect that can be used as a signature of ring eccentricity. We demonstrated the possibility of generating second harmonic response at double resonance condition for incident light polarized along the x-axis if the electric field or/and eccentric barrier break the inversion symmetry. Also, strong third harmonic signal can be generated at triple resonance condition for a specific interval of electric field values when using y-polarized light.

Rigorous theory of molecular orientational nonlinear optics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kwak, Chong Hoon, E-mail: chkwak@ynu.ac.kr; Kim, Gun Yeup

2015-01-15

Classical statistical mechanics of the molecular optics theory proposed by Buckingham [A. D. Buckingham and J. A. Pople, Proc. Phys. Soc. A 68, 905 (1955)] has been extended to describe the field induced molecular orientational polarization effects on nonlinear optics. In this paper, we present the generalized molecular orientational nonlinear optical processes (MONLO) through the calculation of the classical orientational averaging using the Boltzmann type time-averaged orientational interaction energy in the randomly oriented molecular system under the influence of applied electric fields. The focal points of the calculation are (1) the derivation of rigorous tensorial components of the effective molecularmore » hyperpolarizabilities, (2) the molecular orientational polarizations and the electronic polarizations including the well-known third-order dc polarization, dc electric field induced Kerr effect (dc Kerr effect), optical Kerr effect (OKE), dc electric field induced second harmonic generation (EFISH), degenerate four wave mixing (DFWM) and third harmonic generation (THG). We also present some of the new predictive MONLO processes. For second-order MONLO, second-order optical rectification (SOR), Pockels effect and difference frequency generation (DFG) are described in terms of the anisotropic coefficients of first hyperpolarizability. And, for third-order MONLO, third-order optical rectification (TOR), dc electric field induced difference frequency generation (EFIDFG) and pump-probe transmission are presented.« less

Electrical Neural Stimulation and Simultaneous in Vivo Monitoring with Transparent Graphene Electrode Arrays Implanted in GCaMP6f Mice.

PubMed

Park, Dong-Wook; Ness, Jared P; Brodnick, Sarah K; Esquibel, Corinne; Novello, Joseph; Atry, Farid; Baek, Dong-Hyun; Kim, Hyungsoo; Bong, Jihye; Swanson, Kyle I; Suminski, Aaron J; Otto, Kevin J; Pashaie, Ramin; Williams, Justin C; Ma, Zhenqiang

2018-01-23

Electrical stimulation using implantable electrodes is widely used to treat various neuronal disorders such as Parkinson's disease and epilepsy and is a widely used research tool in neuroscience studies. However, to date, devices that help better understand the mechanisms of electrical stimulation in neural tissues have been limited to opaque neural electrodes. Imaging spatiotemporal neural responses to electrical stimulation with minimal artifact could allow for various studies that are impossible with existing opaque electrodes. Here, we demonstrate electrical brain stimulation and simultaneous optical monitoring of the underlying neural tissues using carbon-based, fully transparent graphene electrodes implanted in GCaMP6f mice. Fluorescence imaging of neural activity for varying electrical stimulation parameters was conducted with minimal image artifact through transparent graphene electrodes. In addition, full-field imaging of electrical stimulation verified more efficient neural activation with cathode leading stimulation compared to anode leading stimulation. We have characterized the charge density limitation of capacitive four-layer graphene electrodes as 116.07-174.10 μC/cm 2 based on electrochemical impedance spectroscopy, cyclic voltammetry, failure bench testing, and in vivo testing. This study demonstrates the transparent ability of graphene neural electrodes and provides a method to further increase understanding and potentially improve therapeutic electrical stimulation in the central and peripheral nervous systems.

Light-evoked hyperpolarization and silencing of neurons by conjugated polymers.

PubMed

Feyen, Paul; Colombo, Elisabetta; Endeman, Duco; Nova, Mattia; Laudato, Lucia; Martino, Nicola; Antognazza, Maria Rosa; Lanzani, Guglielmo; Benfenati, Fabio; Ghezzi, Diego

2016-03-04

The ability to control and modulate the action potential firing in neurons represents a powerful tool for neuroscience research and clinical applications. While neuronal excitation has been achieved with many tools, including electrical and optical stimulation, hyperpolarization and neuronal inhibition are typically obtained through patch-clamp or optogenetic manipulations. Here we report the use of conjugated polymer films interfaced with neurons for inducing a light-mediated inhibition of their electrical activity. We show that prolonged illumination of the interface triggers a sustained hyperpolarization of the neuronal membrane that significantly reduces both spontaneous and evoked action potential firing. We demonstrate that the polymeric interface can be activated by either visible or infrared light and is capable of modulating neuronal activity in brain slices and explanted retinas. These findings prove the ability of conjugated polymers to tune neuronal firing and suggest their potential application for the in-vivo modulation of neuronal activity.

Light-evoked hyperpolarization and silencing of neurons by conjugated polymers

PubMed Central

Feyen, Paul; Colombo, Elisabetta; Endeman, Duco; Nova, Mattia; Laudato, Lucia; Martino, Nicola; Antognazza, Maria Rosa; Lanzani, Guglielmo; Benfenati, Fabio; Ghezzi, Diego

2016-01-01

The ability to control and modulate the action potential firing in neurons represents a powerful tool for neuroscience research and clinical applications. While neuronal excitation has been achieved with many tools, including electrical and optical stimulation, hyperpolarization and neuronal inhibition are typically obtained through patch-clamp or optogenetic manipulations. Here we report the use of conjugated polymer films interfaced with neurons for inducing a light-mediated inhibition of their electrical activity. We show that prolonged illumination of the interface triggers a sustained hyperpolarization of the neuronal membrane that significantly reduces both spontaneous and evoked action potential firing. We demonstrate that the polymeric interface can be activated by either visible or infrared light and is capable of modulating neuronal activity in brain slices and explanted retinas. These findings prove the ability of conjugated polymers to tune neuronal firing and suggest their potential application for the in-vivo modulation of neuronal activity. PMID:26940513

Measurement of the internal stress and electric field in a resonating piezoelectric transformer for high-voltage applications using the electro-optic and photoelastic effects

DOE Office of Scientific and Technical Information (OSTI.GOV)

VanGordon, James A.; Kovaleski, Scott D., E-mail: kovaleskis@missouri.edu; Norgard, Peter

The high output voltages from piezoelectric transformers are currently being used to accelerate charged particle beams for x-ray and neutron production. Traditional methods of characterizing piezoelectric transformers (PTs) using electrical probes can decrease the voltage transformation ratio of the device due to the introduction of load impedances on the order of hundreds of kiloohms to hundreds of megaohms. Consequently, an optical diagnostic was developed that used the photoelastic and electro-optic effects present in piezoelectric materials that are transparent to a given optical wavelength to determine the internal stress and electric field. The combined effects of the piezoelectric, photoelastic, and electro-opticmore » effects result in a time-dependent change the refractive indices of the material and produce an artificially induced, time-dependent birefringence in the piezoelectric material. This induced time-dependent birefringence results in a change in the relative phase difference between the ordinary and extraordinary wave components of a helium-neon laser beam. The change in phase difference between the wave components was measured using a set of linear polarizers. The measured change in phase difference was used to calculate the stress and electric field based on the nonlinear optical properties, the piezoelectric constitutive equations, and the boundary conditions of the PT. Maximum stresses of approximately 10 MPa and electric fields of as high as 6 kV/cm were measured with the optical diagnostic. Measured results were compared to results from both a simple one-dimensional (1D) model of the piezoelectric transformer and a three-dimensional (3D) finite element model. Measured stresses and electric fields along the length of an operating length-extensional PT for two different electrical loads were within at least 50 % of 3D finite element simulated results. Additionally, the 3D finite element results were more accurate than the results from the 1D model for a wider range of electrical load impedances under test.« less

Pulsed laser versus electrical energy for peripheral nerve stimulation

PubMed Central

Wells, Jonathon; Konrad, Peter; Kao, Chris; Jansen, E. Duco; Mahadevan-Jansen, Anita

2010-01-01

Transient optical neural stimulation has previously been shown to elicit highly controlled, artifact-free potentials within the nervous system in a non-contact fashion without resulting in damage to tissue. This paper presents the physiologic validity of elicited nerve and muscle potentials from pulsed laser induced stimulation of the peripheral nerve in a comparative study with the standard method of electrically evoked potentials. Herein, the fundamental physical properties underlying the two techniques are contrasted. Key laser parameters for efficient optical stimulation of the peripheral nerve are detailed. Strength response curves are shown to be linear for each stimulation modality, although fewer axons can be recruited with optically evoked potentials. Results compare the relative transient energy requirements for stimulation using each technique and demonstrate that optical methods can selectively excite functional nerve stimulation. Adjacent stimulation and recording of compound nerve potentials in their entirety from optical and electrical stimulation are presented, with optical responses shown to be free of any stimulation artifact. Thus, use of a pulsed laser exhibits some advantages when compared to standard electrical means for excitation of muscle potentials in the peripheral nerve in the research domain and possibly for clinical diagnostics in the future. PMID:17537515

Optical Remote Sensing of Electric Fields Above Thunderstorms

NASA Astrophysics Data System (ADS)

Burns, B. M.; Carlson, B. E.; Lauben, D.; Cohen, M.; Smith, D.; Inan, U. S.

2010-12-01

Measurement of thunderstorm electric fields typically require balloon-borne measurements in the region of interest. Such measurements are cumbersome and provide limited information at a single point. Remote sensing of electric fields by Kerr-effect induced optical polarization changes of background skylight circumvents many of these difficulties and can in principle provide a high-speed movie of electric field behavior. Above-thundercloud 100 kV/m quasi-static electric fields are predicted to produce polarization changes at above the part in one million level that should be detectable at a ground instrument featuring 1 cm2sr geometric factor and 1 kHz bandwidth (though more sensitivity is nonetheless desired). Currently available optical and electronic components may meet these requirements. We review the principles of this measurement and discuss the current status of a field-ready prototype instrument currently in construction.

An optical levitation system for a physics teaching laboratory

NASA Astrophysics Data System (ADS)

Isaksson, Oscar; Karlsteen, Magnus; Rostedt, Mats; Hanstorp, Dag

2018-02-01

We describe an experimental system based on optical levitation of an oil droplet. When combined with an applied electric field and a source of ionizing radiation, the setup permits the investigation of physical phenomena such as radiation pressure, light diffraction, the motion of a charged particle in an oscillating electric field, and the interaction of ionizing radiation with matter. The trapping occurs by creating an equilibrium between a radiation pressure force and the force of gravity. We have found that an oil droplet can be trapped for at least nine hours. The system can be used to measure the size and total electric charge on the trapped droplet. The intensity of the light from the trapping laser that is scattered by the droplet is sufficient to allow the droplet to be easily seen with the naked eye, covered by laser alignment goggles. When oscillating under the influence of an ac electric field, the motion of the droplet can be described as that of a driven, damped harmonic oscillator. The magnitude and polarity of the charge can be altered by exposing the droplet to ionizing radiation from a low-activity radioactive source. Our goal was to design a hands-on setup that allows undergraduate and graduate students to observe and better understand fundamental physical processes.

Combination of optical spectroscopy and electrical impedancemetry for nutrition behavior characterizations

NASA Astrophysics Data System (ADS)

Perchik, Alexey; Pavlov, Konstantin; Vilenskii, Maksim; Popov, Mikhail

2017-07-01

Unhealthy nutrition trends determination technique is described. Combination of optical spectroscopy and electrical impedancemetry will lead to development of a healthcare device that will predict unhealthy eating habits and decrease risk factors of diseases development.

Si/Ge elatform for lasers, amplifiers, and nonlinear optical devices based on the Raman Effect

NASA Astrophysics Data System (ADS)

Claps, Ricardo; Dimitropoulos, Dimitrios; Raghunathan, Varun; Fathpour, Sasan; Jalali, Bahram; Jusserand, Bernard

2007-02-01

The use of a silicon-germanium platform for the development of optically active devices will be discussed in this paper, from the perspective of Raman and Brillouin scattering phenomena. Silicon-Germanium is becoming a prevalent technology for the development of high speed CMOS transistors, with advances in several key parameters as high carrier mobility, low cost, and reduced manufacturing logistics. Traditionally, Si-Ge structures have been used in the optoelectronics arena as photodetectors, due to the enhanced absorption of Ge in the telecommunications band. Recent developments in Raman-based nonlinearities for devices based on a silicon-on-insulator platform have shed light on the possibility of using these effects in Si-Ge architectures. Lasing and amplification have been demonstrated using a SiGe alloy structure, and Brillouin/Raman activity from acoustic phonon modes in SiGe superlattices has been predicted. Moreover, new Raman-active branches and inhomogeneously broadened spectra result from optical phonon modes, offering new perspectives for optical device applications. The possibilities for an electrically-pumped Raman laser will be outlined, and the potential for design and development of silicon-based, Tera-Hertz wave emitters and/or receivers.

Dynamic frequency tuning of electric and magnetic metamaterial response

DOEpatents

O'Hara, John F; Averitt, Richard; Padilla, Willie; Chen, Hou-Tong

2014-09-16

A geometrically modifiable resonator is comprised of a resonator disposed on a substrate, and a means for geometrically modifying the resonator. The geometrically modifiable resonator can achieve active optical and/or electronic control of the frequency response in metamaterials and/or frequency selective surfaces, potentially with sub-picosecond response times. Additionally, the methods taught here can be applied to discrete geometrically modifiable circuit components such as inductors and capacitors. Principally, controlled conductivity regions, using either reversible photodoping or voltage induced depletion activation, are used to modify the geometries of circuit components, thus allowing frequency tuning of resonators without otherwise affecting the bulk substrate electrical properties. The concept is valid over any frequency range in which metamaterials are designed to operate.

Integrated Duo Wavelength VCSEL Using an Electrically Pumped GaInAs/AlGaAs 980 nm Cavity at the Bottom and an Optically Pumped GaInAs/AlGaInAs 1550 nm Cavity on the Top

PubMed Central

Islam, Samiha Ishrat; Islam, Arnob; Islam, Saiful

2014-01-01

In this work, an integrated single chip dual cavity VCSEL has been designed which comprises an electrically pumped 980 nm bottom VCSEL section fabricated using GaInAs/AlGaAs MQW active region and a 1550 nm top VCSEL section constructed using GaInAs/AlGaInAs MQW active region but optically pumped using half of the produced 980 nm light entering into it from the electrically pumped bottom cavity. In this design, the active region of the intracavity structure 980 nm VCSEL consists of 3 quantum wells (QWs) using Ga0.847In0.153As, 2 barriers using Al0.03Ga0.97As, and 2 separate confinement heterostructures (SCH) using the same material as the barrier. The active region of the top emitting 1550 nm VCSEL consists of 3 QWs using Ga0.47In0.52As, 2 barriers using Al0.3Ga0.17In0.53As, and 2 SCHs using the same material as the barrier. The top DBR and the bottom DBR mirror systems of the 1550 nm VCSEL section plus the top and bottom DBR mirror systems of the 980 nm VCSEL section have been formed using GaAs/Al0.8Ga0.2As. Computations show that the VCSEL is capable of producing 8.5 mW of power at 980 nm from the bottom side and 2 mW of power at the 1550 nm from top side. PMID:27379335

Electrically controllable photonic molecule laser.

PubMed

Fasching, G; Deutsch, Ch; Benz, A; Andrews, A M; Klang, P; Zobl, R; Schrenk, W; Strasser, G; Ragulis, P; Tamosiūnas, V; Unterrainer, K

2009-10-26

We have studied the coherent intercavity coupling of the evanescent fields of two microdisk terahertz quantum-cascade lasers. The electrically controllable optical coupling of the single-mode operating lasers has been observed for cavity spacings up to 30 mum. The strongest coupled photonic molecule with 2 mum intercavity spacing allows to conditionally switch the optical emission by the electrical modulation of only one microdisk. The lasing threshold characteristics demonstrate the linear dependence of the gain of a quantum-cascade laser on the applied electric field.

High dynamic range electric field sensor for electromagnetic pulse detection.

PubMed

Lin, Che-Yun; Wang, Alan X; Lee, Beom Suk; Zhang, Xingyu; Chen, Ray T

2011-08-29

We design a high dynamic range electric field sensor based on domain inverted electro-optic (E-O) polymer Y-fed directional coupler for electromagnetic wave detection. This electrode-less, all optical, wideband electrical field sensor is fabricated using standard processing for E-O polymer photonic devices. Experimental results demonstrate effective detection of electric field from 16.7V/m to 750KV/m at a frequency of 1GHz, and spurious free measurement range of 70dB.

Plasmon-enhanced solar energy conversion in organic bulk heterojunction photovoltaics

NASA Astrophysics Data System (ADS)

Morfa, Anthony J.; Rowlen, Kathy L.; Reilly, Thomas H.; Romero, Manuel J.; van de Lagemaat, Jao

2008-01-01

Plasmon-active silver nanoparticle layers were included in solution-processed bulk-heterojunction solar cells. Nanoparticle layers were fabricated using vapor-phase deposition on indium tin oxide electrodes. Owing to the increase in optical electrical field inside the photoactive layer, the inclusion of such particle films lead to increased optical absorption and consequently increased photoconversion at solar-conversion relevant wavelengths. The resulting solar energy conversion efficiency for a bulk heterojunction photovoltaic device of poly(3-hexylthiophene)/[6,6]-phenyl C61 butyric acid methyl ester was found to increase from 1.3%±0.2% to 2.2%±0.1% for devices employing thin plasmon-active layers. Based on six measurements, the improvement factor of 1.7 was demonstrated to be statistically significant.

Imaging Voltage in Genetically Defined Neuronal Subpopulations with a Cre Recombinase-Targeted Hybrid Voltage Sensor.

PubMed

Bayguinov, Peter O; Ma, Yihe; Gao, Yu; Zhao, Xinyu; Jackson, Meyer B

2017-09-20

Genetically encoded voltage indicators create an opportunity to monitor electrical activity in defined sets of neurons as they participate in the complex patterns of coordinated electrical activity that underlie nervous system function. Taking full advantage of genetically encoded voltage indicators requires a generalized strategy for targeting the probe to genetically defined populations of cells. To this end, we have generated a mouse line with an optimized hybrid voltage sensor (hVOS) probe within a locus designed for efficient Cre recombinase-dependent expression. Crossing this mouse with Cre drivers generated double transgenics expressing hVOS probe in GABAergic, parvalbumin, and calretinin interneurons, as well as hilar mossy cells, new adult-born neurons, and recently active neurons. In each case, imaging in brain slices from male or female animals revealed electrically evoked optical signals from multiple individual neurons in single trials. These imaging experiments revealed action potentials, dynamic aspects of dendritic integration, and trial-to-trial fluctuations in response latency. The rapid time response of hVOS imaging revealed action potentials with high temporal fidelity, and enabled accurate measurements of spike half-widths characteristic of each cell type. Simultaneous recording of rapid voltage changes in multiple neurons with a common genetic signature offers a powerful approach to the study of neural circuit function and the investigation of how neural networks encode, process, and store information. SIGNIFICANCE STATEMENT Genetically encoded voltage indicators hold great promise in the study of neural circuitry, but realizing their full potential depends on targeting the sensor to distinct cell types. Here we present a new mouse line that expresses a hybrid optical voltage sensor under the control of Cre recombinase. Crossing this line with Cre drivers generated double-transgenic mice, which express this sensor in targeted cell types. In brain slices from these animals, single-trial hybrid optical voltage sensor recordings revealed voltage changes with submillisecond resolution in multiple neurons simultaneously. This imaging tool will allow for the study of the emergent properties of neural circuits and permit experimental tests of the roles of specific types of neurons in complex circuit activity. Copyright © 2017 the authors 0270-6474/17/379305-15$15.00/0.

Linear and nonlinear magneto-optical absorption in a triangular quantum well

NASA Astrophysics Data System (ADS)

Tung, Luong V.; Vinh, Pham T.; Dinh, Le; Phuc, Huynh V.

2018-05-01

In this work, we study the linear and nonlinear magneto-optical absorption spectrum in a triangular quantum well (TrQW) created by the applied electric field via investigating the phonon-assisted cyclotron resonance (PACR) effect. The results are calculated for a specific Ga0.7Al0.3As/GaAs quantum well. The magneto-optical absorption coefficient (MOAC) and the full width at half maximum (FWHM) are found to be significantly dependent on the magnetic field, the electric field and the temperature. Our results showed that the MOAC and FWHM increase with the magnetic, electric fields and temperature. The obtained results also suggest a useful way to control the magneto-optical properties of TrQW by changing these parameters.

Optical absorption and electrical properties of MPc (M =Fe, Cu, Zn)-TCNQ interfaces for optoelectronic applications

NASA Astrophysics Data System (ADS)

Sánchez Vergara, M. E.; Medrano Gallardo, D.; Vera Estrada, I. L.; Jiménez Sandoval, O.

2018-04-01

This research is related to the growth and characterization of doped molecular semiconductor metallophthalocyanine-tetracyanoquinodimethane (MPc-TCNQ) films, with M = Fe, Zn, Cu. FT-IR and Raman spectroscopies were employed to study the chemical interactions taking place in the MPc-TCNQ films. XRD was carried out to determine the crystalline structure present in the samples, due to the facility of the MPcs to be in alpha and/or beta phases. The thin films were analized by SEM and UV-vis spectroscopy in order to study their morphological and optical properties. The absorption spectra recorded in the UV-Vis region for the deposited samples showed two bands, namely the Q and Soret bands. The absorption coefficient (α) and photon energy (hν) were calculated from the UV-vis spectra, to in turn determine the optic activation energy in each film and its semiconductor behavior. The values obtained for direct transitions due to the crystallinity of the films were: 1.2, 1.4 and 2 eV for FePc-TCNQ (MMFe), ZnPc-TCNQ (MMZn) and CuPc-TCNQ (MMCu), respectively. Additionally, I-V characteristics have been obtained from fabricated glass/ITO/MM/Ag devices using ohmic contacts both after annealing. The electrical properties of the devices, e.g. carrier mobility and concentration of thermally generated holes, were extracted from the J-V characteristics. The results show that the conduction process is ohmic for the MMZn and MMCu devices, at low voltages, while at high voltages, a space-charge-limited conduction (SCLC) is present. The effect of temperature on conductivity was also measured in these samples and the lower thermal activation energy calculated was 0.37 eV for MMZn. Moreover, it was found that the temperature-dependent electric current is always higher for the MMZn device and suggests a semiconductor-like behavior with an important conductivity of the order of 103 S cm-1. Anyhow, in terms not only of electric properties, but also of optic behavior, the results suggest that all three devices manufactured, MMFe, MMCu and MMZn, are of potential use in optoelectronics. The doping effect of TCNQ favors the electronic transport, most likely due to the formation of conduction channels caused by the anisotropy induced by the dopant.

Tunable Optical Filters Having Electro-optic Whispering-gallery-mode Resonators

NASA Technical Reports Server (NTRS)

Savchenkov, Anatoliy (Inventor); Ilchenko, Vladimir (Inventor); Matsko, Andrey B. (Inventor); Maleki, Lutfollah (Inventor)

2006-01-01

Tunable optical filters using whispering-gallery-mode (WGM) optical resonators are described. The WGM optical resonator in a filter exhibits an electro-optical effect and hence is tunable by applying a control electrical signal.

Controllable chaos in hybrid electro-optomechanical systems

PubMed Central

Wang, Mei; Lü, Xin-You; Ma, Jin-Yong; Xiong, Hao; Si, Liu-Gang; Wu, Ying

2016-01-01

We investigate the nonlinear dynamics of a hybrid electro-optomechanical system (EOMS) that allows us to realize the controllable opto-mechanical nonlinearity by driving the microwave LC resonator with a tunable electric field. A controllable optical chaos is realized even without changing the optical pumping. The threshold and lifetime of the chaos could be optimized by adjusting the strength, frequency, or phase of the electric field. This study provides a method of manipulating optical chaos with an electric field. It may offer the prospect of exploring the controllable chaos in on-chip optoelectronic devices and its applications in secret communication. PMID:26948505

Controllable chaos in hybrid electro-optomechanical systems.

PubMed

Wang, Mei; Lü, Xin-You; Ma, Jin-Yong; Xiong, Hao; Si, Liu-Gang; Wu, Ying

2016-03-07

We investigate the nonlinear dynamics of a hybrid electro-optomechanical system (EOMS) that allows us to realize the controllable opto-mechanical nonlinearity by driving the microwave LC resonator with a tunable electric field. A controllable optical chaos is realized even without changing the optical pumping. The threshold and lifetime of the chaos could be optimized by adjusting the strength, frequency, or phase of the electric field. This study provides a method of manipulating optical chaos with an electric field. It may offer the prospect of exploring the controllable chaos in on-chip optoelectronic devices and its applications in secret communication.

Introducing Magneto-Optical Functions into Soft Materials

DTIC Science & Technology

2017-05-03

the electromagnet as illustrated in Figure 1(b). This experimental measurement allowed us to explore magneto- electric coupling in both ground and...short-range spin-spin interaction. As a general conclusion, the -d electron coupling promise the existence of photo-adjustable magneto- electric ...coupling, paving the way for the realization of magneto- electric -optical applications. Intermoleuar SOC SB Orb S B OrbHinter Hinter 1 2 (b

Voltage Sensor

NASA Technical Reports Server (NTRS)

1996-01-01

Under a Lewis Research Center Small Business Innovation Research contract, SRICO, Inc. developed a fiber optic voltage sensor to measure voltage in electronic systems in spacecraft. The sensor uses glass and light to sense and transmit electricity, and is relatively safe and accurate. SRICO then commercialized the sensor for measurement of electric field and voltage in applications such as electric power systems and hazardous environments, lightning detection, and fiber optic communication systems.

Distributed measurement of high electric current by means of polarimetric optical fiber sensor.

PubMed

Palmieri, Luca; Sarchi, Davide; Galtarossa, Andrea

2015-05-04

A novel distributed optical fiber sensor for spatially resolved monitoring of high direct electric current is proposed and analyzed. The sensor exploits Faraday rotation and is based on the polarization analysis of the Rayleigh backscattered light. Preliminary laboratory tests, performed on a section of electric cable for currents up to 2.5 kA, have confirmed the viability of the method.

Electro-Optic Lightning Detector

NASA Technical Reports Server (NTRS)

Koshak, William J.; Solakiewica, R. J.

1998-01-01

Electric field measurements are fundamental to the study of thunderstorm electrification, thundercloud charge structure, and the determination of the locations and magnitudes of charges deposited by lightning. Continuous field observations can also be used to warn of impending electrical hazards. For example, the USAF Eastern Range (ER) and NASA Kennedy Space Center (KSC) in Florida currently operate a ground-based network of electric field mill sensors to warn against lightning hazards to space vehicle operations/launches. The sensors provide continuous recordings of the ambient field. Others investigators have employed flat-plate electric field antennas to detect changes In the ambient field due to lightning. In each approach, electronic circuitry is used to directly detect and amplify the effects of the ambient field on an exposed metal conductor (antenna plate); in the case of continuous field recordings, the antenna plate is alternately shielded and unshielded by a grounded conductor. In this work effort, an alternate optical method for detecting lightning-caused electric field changes is Introduced. The primary component in the detector is an anisotropic electro-optic crystal of potassium di-hydrogen phosphate (chemically written as KH2PO4 (KDP)). When a voltage Is placed across the electro-optic crystal, the refractive Indices of the crystal change. This change alters the polarization state of a laser light beam that is passed down the crystal optic axis. With suitable application of vertical and horizontal polarizers, a light transmission measurement is related to the applied crystal voltage (which in turn Is related to the lightning caused electric field change). During the past two years, all critical optical components were procured, assembled, and aligned. An optical housing, calibration set-up, and data acquisition system was integrated for breadboard testing. The sensor was deployed at NASA Marshall Space Flight Center (MSFC) in the summer of 1998 to collect storm data. Because solid-state technology is used, future designs of the sensor will be significantly scaled down In physical dimension and weight compared to the present optical breadboard prototype. The use of fiber optics would also provide significant practical improvements.

Fiber optic multiplex optical transmission system

NASA Technical Reports Server (NTRS)

Bell, C. H. (Inventor)

1977-01-01

A multiplex optical transmission system which minimizes external interference while simultaneously receiving and transmitting video, digital data, and audio signals is described. Signals are received into subgroup mixers for blocking into respective frequency ranges. The outputs of these mixers are in turn fed to a master mixer which produces a composite electrical signal. An optical transmitter connected to the master mixer converts the composite signal into an optical signal and transmits it over a fiber optic cable to an optical receiver which receives the signal and converts it back to a composite electrical signal. A de-multiplexer is coupled to the output of the receiver for separating the composite signal back into composite video, digital data, and audio signals. A programmable optic patch board is interposed in the fiber optic cables for selectively connecting the optical signals to various receivers and transmitters.

Multispectral Visible/Infrared Sensors Based on Polymer-Metal Nanocomposites

DTIC Science & Technology

2010-01-06

transport in the dielectric zone is governed by an activated tunneling process, while the electron transport in the metallic zone can be described by...electrical pathway has formed at this stage, and thermally activated tunneling dominates the charge transport. At very high metal concentration, metallic...25 -20 -15 -10 -5 0 5 10 Cu rre nt , m A Bias Voltage, V Dark Bright Bright >850 nm Figure 12a. Optical absorption spectrum of Blackberry dye

Adaptive Optics at Lawrence Livermore National Laboratory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gavel, D T

2003-03-10

Adaptive optics enables high resolution imaging through the atmospheric by correcting for the turbulent air's aberrations to the light waves passing through it. The Lawrence Livermore National Laboratory for a number of years has been at the forefront of applying adaptive optics technology to astronomy on the world's largest astronomical telescopes, in particular at the Keck 10-meter telescope on Mauna Kea, Hawaii. The technology includes the development of high-speed electrically driven deformable mirrors, high-speed low-noise CCD sensors, and real-time wavefront reconstruction and control hardware. Adaptive optics finds applications in many other areas where light beams pass through aberrating media andmore » must be corrected to maintain diffraction-limited performance. We describe systems and results in astronomy, medicine (vision science), and horizontal path imaging, all active programs in our group.« less

Compact and low power operation optical switch using silicon-germanium/silicon hetero-structure waveguide.

PubMed

Sekiguchi, Shigeaki; Kurahashi, Teruo; Zhu, Lei; Kawaguchi, Kenichi; Morito, Ken

2012-04-09

We proposed a silicon-based optical switch with a carrier-plasma-induced phase shifter which employs a silicon-germanium (SiGe) / silicon (Si) hetero-structure in the waveguide core. A type-I hetero-interface formed by SiGe and Si is expected to confine carriers effectively in the SiGe waveguide core. The fabricated Mach-Zehnder optical switch shows a low switching power of only 1.53 mW with a compact phase shifter length of 250 μm. The switching time of the optical switch is less than 4.6 ns for the case of a square waveform driving condition, and 1 ns for the case of a pre-emphasis electric driving condition. These results show that our proposed SiGe/Si waveguide structure holds promise for active devices with compact size and low operation power.

Optical effects of shadow masks on short circuit current of organic photovoltaic devices.

PubMed

Lin, Chi-Feng; Lin, Bing-Hong; Liu, Shun-Wei; Hsu, Wei-Feng; Zhang, Mi; Chiu, Tien-Lung; Wei, Mau-Kuo; Lee, Jiun-Haw

2012-03-21

In this paper, we have employed different shadow masks attached on top of organic photovoltaic (OPV) devices to study the optical effects of the former on the short circuit current (J(SC)). To rule out possible lateral electrical conduction and simplify the optical effects inside the device, a small-molecular heterojunction OPV device with a clear donor/acceptor interface was employed with a hole extraction layer exhibiting high resistance intentionally. Careful calibration with a shadow mask was employed. By attaching two layers of opaque masks in combination with a suitable holder design to shield the light from the edges and backside, the value of J(SC) approached that of the dark current, even under 1-sun radiation. With different illumination areas, we found that the photons illuminating the non-active region of the device contributed to 40% of the J(SC) by optical effect within the width of about 1 mm around the active region. When illuminating the non-active area with 12 mm to the active area, a 5.6 times improvement in the J(SC) was observed when the incident angle was 75°. With the introduction of a microstructured film onto the OPV device and an increase in the reflection from the non-active region, a 15% enhancement of the J(SC) compared to the control device was achieved.

Low noise optical position sensor

DOEpatents

Spear, J.D.

1999-03-09

A novel optical position sensor is described that uses two component photodiodes electrically connected in parallel, with opposing polarities. A lens provides optical gain and restricts the acceptance angle of the detector. The response of the device to displacements of an optical spot is similar to that of a conventional bi-cell type position sensitive detector. However, the component photodiode design enables simpler electronic amplification with inherently less electrical noise than the bi-cell. Measurements by the sensor of the pointing noise of a focused helium-neon laser as a function of frequency demonstrate high sensitivity and suitability for optical probe beam deflection experiments. 14 figs.

Low noise optical position sensor

DOEpatents

Spear, Jonathan David

1999-01-01

A novel optical position sensor is described that uses two component photodiodes electrically connected in parallel, with opposing polarities. A lens provides optical gain and restricts the acceptance angle of the detector. The response of the device to displacements of an optical spot is similar to that of a conventional bi-cell type position sensitive detector. However, the component photodiode design enables simpler electronic amplification with inherently less electrical noise than the bi-cell. Measurements by the sensor of the pointing noise of a focused helium-neon laser as a function of frequency demonstrate high sensitivity and suitability for optical probe beam deflection experiments.

Intense transient electric field sensor based on the electro-optic effect of LiNbO{sub 3}

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Qing, E-mail: yangqing@cqu.edu.cn; Sun, Shangpeng; Han, Rui

2015-10-15

Intense transient electric field measurements are widely applied in various research areas. An optical intense E-field sensor for time-domain measurements, based on the electro-optic effect of lithium niobate, has been studied in detail. Principles and key issues in the design of the sensor are presented. The sensor is insulated, small in size (65 mm × 15 mm × 15 mm), and suitable for high-intensity (<801 kV/m) electric field measurements over a wide frequency band (10 Hz–10 MHz). The input/output characteristics of the sensor were obtained and the sensor calibrated. Finally, an application using this sensor in testing laboratory lightning impulsesmore » and in measuring transient electric fields during switch-on of a disconnector confirmed that the sensor is expected to find widespread use in transient intense electric field measurement applications.« less

Intense transient electric field sensor based on the electro-optic effect of LiNbO3

NASA Astrophysics Data System (ADS)

Yang, Qing; Sun, Shangpeng; Han, Rui; Sima, Wenxia; Liu, Tong

2015-10-01

Intense transient electric field measurements are widely applied in various research areas. An optical intense E-field sensor for time-domain measurements, based on the electro-optic effect of lithium niobate, has been studied in detail. Principles and key issues in the design of the sensor are presented. The sensor is insulated, small in size (65 mm × 15 mm × 15 mm), and suitable for high-intensity (<801 kV/m) electric field measurements over a wide frequency band (10 Hz-10 MHz). The input/output characteristics of the sensor were obtained and the sensor calibrated. Finally, an application using this sensor in testing laboratory lightning impulses and in measuring transient electric fields during switch-on of a disconnector confirmed that the sensor is expected to find widespread use in transient intense electric field measurement applications.

Influences of film thickness on the structural, electrical and optical properties of CuAlO2 thin films

NASA Astrophysics Data System (ADS)

Dong, Guobo; Zhang, Ming; Wang, Mei; Li, Yingzi; Gao, Fangyuan; Yan, Hui; Diao, Xungang

2014-07-01

CuAlO2 films with different thickness were prepared by the radio frequency magnetron sputtering technique. The structural, electrical and optical properties of CuAlO2 were studied by X-ray diffraction, atomic force microscope, UV-Vis double-beam spectrophotometer and Hall measurements. The results indicate that the single phase hexagonal CuAlO2 is formed and the average grain size of CuAlO2 films increases with increasing film thickness. The results also exhibit that the lowering of bandgap and the increase of electrical conductivity of CuAlO2 films with the increase of their thickness, which are attributed to the improvement of the grain size and the anisotropic electrical property. According to the electrical and optical properties, the biggest figure of merit is achieved for the CuAlO2 film with the appropriate thickness of 165 nm.

Electrical Versus Optical: Comparing Methods for Detecting Terahertz Radiation Using Neon Lamps

NASA Astrophysics Data System (ADS)

Slocombe, L. L.; Lewis, R. A.

2018-05-01

Terahertz radiation impinging on a lit neon tube causes additional ionization of the encapsulated gas. As a result, the electrical current flowing between the electrodes increases and the glow discharge in the tube brightens. These dual phenomena suggest two distinct modes of terahertz sensing. The electrical mode simply involves measuring the electrical current. The optical mode involves monitoring the brightness of the weakly ionized plasma glow discharge. Here, we directly compare the two detection modes under identical experimental conditions. We measure 0.1-THz radiation modulated at frequencies in the range 0.1-10 kHz, for lamp currents in the range 1-10 mA. We find that electrical detection provides a superior signal-to-noise ratio while optical detection has a faster response. Either method serves as the basis of a compact, robust, and inexpensive room-temperature detector of terahertz radiation.

The effects of a geometrical size, external electric fields and impurity on the optical gain of a quantum dot laser with a semi-parabolic spherical well potential

NASA Astrophysics Data System (ADS)

Owji, Erfan; Keshavarz, Alireza; Mokhtari, Hosein

2017-03-01

In this paper, a GaAs / Alx Ga1-x As quantum dot laser with a semi-parabolic spherical well potential is assumed. By using Runge-Kutta method the eigenenergies and the eigenstates of valence and conduct bands are obtained. The effects of geometrical sizes, external electric fields and hydrogen impurity on the different electronic transitions of the optical gain are studied. The results show that the optical gain peak increases and red-shifts, by increasing the width of well or barrier, while more increasing of the width causes blue-shift and decreases it. The hydrogen impurity decreases the optical gain peak and blue-shifts it. Also, the increasing of the external electric fields cause to increase the peak of the optical gain, and (blue) red shift it. Finally, the optical gain for 1s-1s and 2s-1s transitions is prominent, while it is so weak for other transitions.

Optical Characterization and 2,525 micron Lasing of Cr(2+):Cd(0.85)Mn(0.15)Te

NASA Technical Reports Server (NTRS)

Davis, V. R.; Wu, X.; Hoemmerich, U.; Trivedi, S. B.; Grasza, K.; Yu, Z.

1997-01-01

Transition metal doped solids are of significant current interest for the development of tunable solid-state lasers for the near and mid-infrared (1-4 pm) spectral region. Applications of these lasers include basic research in atomic, molecular, and solid-state physics, optical communication, medicine, and environmental studies of the atmosphere. In transition metal based laser materials, absorption and emission of light arises from electronic transitions between crystal field split energy levels of 3d transition metal ions. The optical spectra generally exhibit broad bands due to the strong interaction between dopant and host (electron-phonon coupling). Broad emission bands offer the prospect of tunable laser activity over a wide wavelength range, e.g. the tuning range of Ti:Sapphire extends from 700-1100 run. The only current transition metal laser operating in the mid-infrared wavelength region (1.8-2.4 micro-m) is CO(2+):MgF2, but its performance is severely limited due to strong nonradiative decay at room temperature. Based on lifetime data, the quantum efficiency is estimated to be less than 3 deg/0 11,21. In general, the probability for non-radiative decay via multi-phonon relaxation increases with decreasing energy gap between ground and excited state. Therefore, efficient transition metal lasers beyond -1.6 micro-m are rare. Recently, tunable laser activity around 2.3 micro-m was observed from Cr doped ZnS and ZnSe. The new lasing center in these materials was identified as Cr(2+) occupying the tetrahedral Zn site. Tetrahedrally coordinated optical centers are rather unusual among transition metal lasers. Their potential usefulness, however, has been demonstrated by the recent development of near infrared laser materials such as Cr:forsterite and Cr:YAG, which are based on tetrahedrally coordinated Cr(4+) ions. According to the Laporte selection rule, electric-dipole transition within the optically active 3d-electron shells are parity forbidden. However, a static acentric electric crystal field or the coupling of asymmetric phonons can force electric-dipole transitions by the admixture of wave functions with opposite parity. Tetrahedral sites lack inversion symmetry which provides the odd-parity field necessary to relax the parity selection rule. Therefore, high absorption and emission cross sections are observed. An enhanced radiative emission rate is also expected to reduce the detrimental effect of non-radiative decay. Motivated by the initial results on Cr doped ZnS and ZnSe, we have started a comprehensive effort to study Cr(2+) doped II-VI semiconductors for solid-state laser applications. In this paper we present the optical properties and the demonstration of mid-infrared lasing from Cr doped Cd(0.85)Mn(0.15)Te.

Adaptive metalenses with simultaneous electrical control of focal length, astigmatism, and shift.

PubMed

She, Alan; Zhang, Shuyan; Shian, Samuel; Clarke, David R; Capasso, Federico

2018-02-01

Focal adjustment and zooming are universal features of cameras and advanced optical systems. Such tuning is usually performed longitudinally along the optical axis by mechanical or electrical control of focal length. However, the recent advent of ultrathin planar lenses based on metasurfaces (metalenses), which opens the door to future drastic miniaturization of mobile devices such as cell phones and wearable displays, mandates fundamentally different forms of tuning based on lateral motion rather than longitudinal motion. Theory shows that the strain field of a metalens substrate can be directly mapped into the outgoing optical wavefront to achieve large diffraction-limited focal length tuning and control of aberrations. We demonstrate electrically tunable large-area metalenses controlled by artificial muscles capable of simultaneously performing focal length tuning (>100%) as well as on-the-fly astigmatism and image shift corrections, which until now were only possible in electron optics. The device thickness is only 30 μm. Our results demonstrate the possibility of future optical microscopes that fully operate electronically, as well as compact optical systems that use the principles of adaptive optics to correct many orders of aberrations simultaneously.

Electronic properties and optical absorption of a phosphorene quantum dot

NASA Astrophysics Data System (ADS)

Liang, F. X.; Ren, Y. H.; Zhang, X. D.; Jiang, Z. T.

2018-03-01

Using the tight-binding Hamiltonian approach, we theoretically study the electronic and optical properties of a triangular phosphorene quantum dot (PQD) including one normal zigzag edge and two skewed armchair edges (ZAA-PQD). It is shown that the energy spectrum can be classified into the filled band (FB), the zero-energy band (ZB), and the unfilled band (UB). Numerical calculations of the FB, ZB, and UB probability distributions show that the FB and the UB correspond to the bulk states, while the ZB corresponds to the edge states, which appear on all of the three edges of the ZAA-PQD sharply different from the other PQDs. We also find that the strains and the electric fields can affect the energy levels inhomogeneously. Then the optical properties of the ZAA-PQD are investigated. There appear some strong low-energy optical absorption peaks indicating its sensitive low-energy optical response that is absent in other PQDs. Moreover, the strains and the electric fields can make inhomogeneous influences on the optical spectrum of the ZAA-PQD. This work may provide a useful reference for designing the electrical, mechanical, and optical PQD devices.

New insights on electro-optical response of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) film to humidity

DOE PAGES

Sumpter, Bobby G.; Ivanov, Ilia N.; Kumar, Rajeev; ...

2017-04-26

Understanding the relative humidity (RH) response of poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) is critical for improving the stability of organic electronic devices and developing selective sensors. In this work combined gravimetric sensing, nanoscale surface probing, and mesoscale optoelectronic characterization are used to directly compare the RH dependence of electrical and optical conductivities and unfold connections between the rate of water adsorption and changes in functional properties of PEDOT:PSS film. We report three distinct regimes where changes in electrical conductivity, optical conductivity, and optical bandgap are correlated with the mass of adsorbed water. At low (RH < 25%) and high (RH > 60%) humiditymore » levels dramatic changes in electrical, optical and structural properties occur, while changes are insignificant in mid-RH (25% < RH < 60%) conditions. We associate the three regimes with water adsorption at hydrophilic moieties at low RH, diffusion and swelling throughout the film at mid-RH, and saturation of the film by water at high RH. Optical film thickness increased by 150% as RH was increased from 9% to 80%. Low frequency (1 kHz) impedance increased by ~100% and film capacitance increased by ~30% as RH increased from 9% to 80% due to an increase in the film dielectric constant. Finally, changes in electrical and optical conductivities concomitantly decrease across the full range of RH tested.« less

Optical manipulation and catalytic activity enhanced by surface plasmon effect

NASA Astrophysics Data System (ADS)

Zou, Ningmu; Min, Jiang; Jiao, Wenxiang; Wang, Guanghui

2017-02-01

For optical manipulation, a nano-optical conveyor belt consisting of an array of gold plasmonic non-concentric nano-rings (PNNRs) is demonstrated for the realization of trapping and unidirectional transportation of nanoparticles by polarization rotation of excitation beam. These hot spots of an asymmetric plasmonic nanostructure are polarization dependent, therefore, one can use the incident polarization state to manipulate the trapped targets. Trapped particles could be transferred between adjacent PNNRs in a given direction just by rotating the polarization of incident beam due to unbalanced potential. The angular dependent distribution of electric field around PNNR has been solved using the three- dimensional finite-difference time-domain (FDTD) technique. For optical enhanced catalytic activity, the spectral properties of dimers of Au nanorod-Au nanorod nanostructures under the excitation of 532nm photons have been investigated. With a super-resolution catalytic mapping technique, we identified the existence of "hot spot" in terms of catalytic reactivity at the gap region within the twined plasmonic nanostructure. Also, FDTD calculation has revealed an intrinsic correlation between hot electron transfer.

A Matlab toolkit for three-dimensional electrical impedance tomography: a contribution to the Electrical Impedance and Diffuse Optical Reconstruction Software project

NASA Astrophysics Data System (ADS)

Polydorides, Nick; Lionheart, William R. B.

2002-12-01

The objective of the Electrical Impedance and Diffuse Optical Reconstruction Software project is to develop freely available software that can be used to reconstruct electrical or optical material properties from boundary measurements. Nonlinear and ill posed problems such as electrical impedance and optical tomography are typically approached using a finite element model for the forward calculations and a regularized nonlinear solver for obtaining a unique and stable inverse solution. Most of the commercially available finite element programs are unsuitable for solving these problems because of their conventional inefficient way of calculating the Jacobian, and their lack of accurate electrode modelling. A complete package for the two-dimensional EIT problem was officially released by Vauhkonen et al at the second half of 2000. However most industrial and medical electrical imaging problems are fundamentally three-dimensional. To assist the development we have developed and released a free toolkit of Matlab routines which can be employed to solve the forward and inverse EIT problems in three dimensions based on the complete electrode model along with some basic visualization utilities, in the hope that it will stimulate further development. We also include a derivation of the formula for the Jacobian (or sensitivity) matrix based on the complete electrode model.

Preliminary Optical And Electric Field Pulse Statistics From Storm Overflights During The Altus Cumulus Electrification Study

NASA Technical Reports Server (NTRS)

Mach, D. A.; Blakeslee, R. J.; Bailey, J. C.; Farrell, W. M.; Goldberg, R. A.; Desch, M. D.; Houser, J. G.

2003-01-01

The Altus Cumulus Electrification Study (ACES) was conducted during the month of August, 2002 in an area near Key West, Florida. One of the goals of this uninhabited aerial vehicle (UAV) study was to collect high resolution optical pulse and electric field data from thunderstorms. During the month long campaign, we acquired 5294 lightning generated optical pulses with associated electric field changes. Most of these observations were made while close to the top of the storms. We found filtered mean and median 10-10% optical pulse widths of 875 and 830 microns respectively while the 50-50% mean and median optical pulse widths are 422 and 365 microns respectively. These values are similar to previous results as are the 10-90% mean and median rise times of 327 and 265 microns. The peak electrical to optical pulse delay mean and median were 209 and 145 microns which is longer than one would expect from theoretical results. The results of the pulse analysis will contribute to further validation of the Optical Transient Detector (OTD) and the Lightning Imaging Sensor (LIS) satellites. Pre-launch estimates of the flash detection efficiency were based on a small sample of optical pulse measurements associated with less than 350 lightning discharges collected by NASA U-2 aircraft in the early 1980s. Preliminary analyses of the ACES measurements show that we have greatly increased the number of optical pulses available for validation of the LIS and other orbital lightning optical sensors. Since the Altus was often close to the cloud tops, many of the optical pulses are from low-energy pulses. From these low-energy pulses, we can determine the fraction of optical lightning pulses below the thresholds of LIS, OTD, and any future satellite-based optical sensors such as the geostationary Lightning Mapping Sensor.

Impact of active layer thickness of nitrogen-doped In–Sn–Zn–O films on materials and thin film transistor performances

NASA Astrophysics Data System (ADS)

Li, Zhi-Yue; Yang, Hao-Zhi; Chen, Sheng-Chi; Lu, Ying-Bo; Xin, Yan-Qing; Yang, Tian-Lin; Sun, Hui

2018-05-01

Nitrogen-doped indium tin zinc oxide (ITZO:N) thin film transistors (TFTs) were deposited on SiO2 (200 nm)/p-Si〈1 0 0〉 substrates by RF magnetron sputtering at room temperature. The structural, chemical compositions, surface morphology, optical and electrical properties as a function of the active layer thickness were investigated. As the active layer thickness increases, Zn content decreases and In content increases gradually. Meanwhile, Sn content is almost unchanged. When the thickness of the active layer is more than 45 nm, the ITZO:N films become crystallized and present a crystal orientation along InN(0 0 2) plan. No matter what the thickness is, ITZO:N films always display a high transmittance above 80% in the visible region. Their optical band gaps fluctuate between 3.4 eV and 3.62 eV. Due to the dominance of low interface trap density and high carrier concentration, ITZO:N TFT shows enhanced electrical properties as the active layer thickness is 35 nm. Its field-effect mobility, on/off radio and sub-threshold swing are 17.53 cm2 V‑1 · s‑1, 106 and 0.36 V/dec, respectively. These results indicate that the suitable thickness of the active layer can enhance the quality of ITZO:N films and decrease the defects density of ITZO:N TFT. Thus, the properties of ITZO:N TFT can be optimized by adjusting the thickness of the active layer.

Spatial Light Modulators with Arbitrary Quantum Wells Profiles

DTIC Science & Technology

1993-09-27

phase change in the 1.152Pm wave propagating through the waveguide and appears as an optically bistable intensity signal normal to the control beam ...electrical bistability of a SEED was integrated with a phase modulator to produce optical bistability in an all- optical switch. A control wavelength of...received attention for its use in electrically-addressable spatial light intensity modulator arrays due to its potentially high contrast ratio, large

Towards roll-to-roll fabrication of electronics, optics, and optoelectronics for smart and intelligent packaging

NASA Astrophysics Data System (ADS)

Kololuoma, Terho K.; Tuomikoski, Markus; Makela, Tapio; Heilmann, Jali; Haring, Tomi; Kallioinen, Jani; Hagberg, Juha; Kettunen, Ilkka; Kopola, Harri K.

2004-06-01

Embedding of optoelectrical, optical, and electrical functionalities into low-cost products like packages and printed matter can be used to increase their information content. These functionalities make also possible the realization of new type of entertaining, impressive or guiding effects on the product packages and printed matter. For these purposes, components like displays, photodetectors, light sources, solar cells, battery elements, diffractive optical elements, lightguides, electrical conductors, resistors, transistors, switching elements etc. and their integration to functional modules are required. Additionally, the price of the components for low-end products has to be in cent scale or preferably below that. Therefore, new, cost-effective, and volume scale capable manufacturing techniques are required. Recent developments of liquid-phase processable electrical and optical polymeric, inorganic, and hybrid materials - inks - have made it possible to fabricate functional electrical, optical and optoelectrical components by conventional roll-to-roll techniques such as gravure printing, embossing, digital printing, offset, and screen printing on flexible paper and plastic like substrates. In this paper, we show our current achievements in the field of roll-to-roll fabricated, optics, electronics and optoelectronics. With few examples, we also demonstrate the printing and hot-embossing capabilities of table scale printing machines and VTT Electronic's 'PICO' roll-to-roll pilot production facility.

Preliminary photovoltaic arc-fault prognostic tests using sacrificial fiber optic cabling.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnson, Jay Dean; Blemel, Kenneth D.; Peter, Francis

2013-02-01

Through the New Mexico Small Business Assistance Program, Sandia National Laboratories worked with Sentient Business Systems, Inc. to develop and test a novel photovoltaic (PV) arc-fault detection system. The system operates by pairing translucent polymeric fiber optic sensors with electrical circuitry so that any external abrasion to the system or internal heating causes the fiber optic connection to fail or detectably degrade. A periodic pulse of light is sent through the optical path using a transmitter-receiver pair. If the receiver does not detect the pulse, an alarm is sounded and the PV system can be de-energized. This technology has themore » unique ability to prognostically determine impending failures to the electrical system in two ways: (a) the optical connection is severed prior to physical abrasion or cutting of PV DC electrical conductors, and (b) the polymeric fiber optic cable melts via Joule heating before an arc-fault is established through corrosion. Three arc-faults were created in different configurations found in PV systems with the integrated fiber optic system to determine the feasibility of the technology. In each case, the fiber optic cable was broken and the system annunciated the fault.« less

Modification of the electrical, optical and thermal properties of L-Arginine Perchlorate single crystals by 5 kGy and 8 kGy electron beam irradiation for optoelectronic devices

NASA Astrophysics Data System (ADS)

Thomas, Prince; Santhosh Kumar, R.; Sreekanth, G.; John, Bitto; Sanjeev, Ganesh; Joseph, Ginson P.

2017-11-01

This paper attempts to elucidate the effect of 5 kGy and 8 kGy electron irradiation on the optical, thermal and electrical properties of a prominent amino acid crystal, L-Arginine Perchlorate (LAPCl) grown by low-temperature solution growth technique. Optical absorption studies revealed that the UV lower cut-off wavelength shift towards the higher wavelength region (Red shift), the optical band gap of LAPCl were found to be decreasing while the Urbach energy was found to be increasing with increasing the dosage of irradiation. Fourier Transform Infrared (FT-IR) spectroscopic result showed that peak intensities corresponding to typical bonding increase with the increase in electron beam irradiation dosage. Electrical studies revealed that the dielectric constant, loss and conductivity of the sample increases with increasing the dosage of irradiation. The behaviour of electrical properties on temperature and thermal properties has also been investigated.

Optical Diode Effect at Spin-Wave Excitations of the Room-Temperature Multiferroic BiFeO_{3}.

PubMed

Kézsmárki, I; Nagel, U; Bordács, S; Fishman, R S; Lee, J H; Yi, Hee Taek; Cheong, S-W; Rõõm, T

2015-09-18

Multiferroics permit the magnetic control of the electric polarization and the electric control of the magnetization. These static magnetoelectric (ME) effects are of enormous interest: The ability to read and write a magnetic state current-free by an electric voltage would provide a huge technological advantage. Dynamic or optical ME effects are equally interesting, because they give rise to unidirectional light propagation as recently observed in low-temperature multiferroics. This phenomenon, if realized at room temperature, would allow the development of optical diodes which transmit unpolarized light in one, but not in the opposite, direction. Here, we report strong unidirectional transmission in the room-temperature multiferroic BiFeO_{3} over the gigahertz-terahertz frequency range. The supporting theory attributes the observed unidirectional transmission to the spin-current-driven dynamic ME effect. These findings are an important step toward the realization of optical diodes, supplemented by the ability to switch the transmission direction with a magnetic or electric field.

Novel gas sensor with dual response under CO(g) exposure: Optical and electrical stimuli

NASA Astrophysics Data System (ADS)

Rocha, L. S. R.; Cilense, M.; Ponce, M. A.; Aldao, C. M.; Oliveira, L. L.; Longo, E.; Simoes, A. Z.

2018-05-01

In this work, a lanthanum (La) doped ceria (CeO2) film, which depicted a dual gas sensing response (electric and optical) for CO(g) detection, was obtained by the microwave-assisted hydrothermal (HAM) synthesis and deposited by the screen-printing technique, in order to prevent deaths by intoxication with this life-threatening gas. An electric response under CO(g) exposure was obtained, along with an extremely fast optical response for a temperature of 380 °C, associated with Ce+4 reduction and vacancy generation. A direct optical gap was found to be around 2.31 eV from UV-Vis results, which corresponds to a transition from valence band to 4f states. Due to the anomalous electron configuration of cerium atoms with 4f electrons in its reduced state, they are likely to present an electric conduction based on the small polaron theory with a hopping mechanism responsible for its dual sensing response with a complete reversible behaviour.

About the feasibilities of controlling the properties of thermoelectric energy converters using optical radiation

NASA Astrophysics Data System (ADS)

Kshevetsky, Oleg S.

2018-01-01

We represent evaluating analysis of the feasibilities for controlling the properties of thermoelectric energy converters using EM radiation in the regimes of cooling, heating, electromotive force generation, or electric current generation. Thus we investigate the influence of optical radiation both on electric conductivity and thermo-electromotive force coefficient of thermoelectric materials. We also discuss promising applications for controlling the properties of thermoelectric energy converters using EM radiation. We represent the results of experimental study of positionsensitive energy converters in the regimes of electromotive force generation and the electric current generation (in part, photo-thermoelectric position-sensitive temperature detectors), position-sensitive photo-thermoelectric energy converters in the regimes of cooling, heating, parallel photoelectric and thermoelectric conversion of sun-light optical radiation into electric power.

Materials characterization study of conductive flexible second surface mirrors

NASA Technical Reports Server (NTRS)

Levadou, F.; Bosma, S. J.; Paillous, A.

1981-01-01

The status of prequalification and qualification work on conductive flexible second surface mirrors is described. The basic material is FEP Teflon witn either aluminium or silver vacuum deposited reflectors. The top layer has been made conductive by deposition of layer of a indium oxide. The results of a prequalification program comprised of decontamination, humidity, thermal cycling, thermal shock and vibration tests are presented. Thermo-optical and electrical properties. The results of a prequalification program comprised of decontamination, humidity, thermal cycling, thermal shock and vibration tests are presented. Thermo-optical and electrical properties, the electrostatic behavior of the materials under simulated substorm environment and electrical conductivity at low temperatures are characterized. The effects of simulated ultra violet and particles irradiation on electrical and thermo-optical properties of the materials are also presented.

Transparent conductor-embedding nanocones for selective emitters: optical and electrical improvements of Si solar cells

PubMed Central

Kim, Joondong; Yun, Ju-Hyung; Kim, Hyunyub; Cho, Yunae; Park, Hyeong-Ho; Kumar, M. Melvin David; Yi, Junsin; Anderson, Wayne A.; Kim, Dong-Wook

2015-01-01

Periodical nanocone-arrays were employed in an emitter region for high efficient Si solar cells. Conventional wet-etching process was performed to form the nanocone-arrays for a large area, which spontaneously provides the graded doping features for a selective emitter. This enables to lower the electrical contact resistance and enhances the carrier collection due to the high electric field distribution through a nanocone. Optically, the convex-shaped nanocones efficiently reduce light-reflection and the incident light is effectively focused into Si via nanocone structure, resulting in an extremely improved the carrier collection performances. This nanocone-arrayed selective emitter simultaneously satisfies optical and electrical improvement. We report the record high efficiency of 16.3% for the periodically nanoscale patterned emitter Si solar cell. PMID:25787933

Transparent conductor-embedding nanocones for selective emitters: optical and electrical improvements of Si solar cells.

PubMed

Kim, Joondong; Yun, Ju-Hyung; Kim, Hyunyub; Cho, Yunae; Park, Hyeong-Ho; Kumar, M Melvin David; Yi, Junsin; Anderson, Wayne A; Kim, Dong-Wook

2015-03-19

Periodical nanocone-arrays were employed in an emitter region for high efficient Si solar cells. Conventional wet-etching process was performed to form the nanocone-arrays for a large area, which spontaneously provides the graded doping features for a selective emitter. This enables to lower the electrical contact resistance and enhances the carrier collection due to the high electric field distribution through a nanocone. Optically, the convex-shaped nanocones efficiently reduce light-reflection and the incident light is effectively focused into Si via nanocone structure, resulting in an extremely improved the carrier collection performances. This nanocone-arrayed selective emitter simultaneously satisfies optical and electrical improvement. We report the record high efficiency of 16.3% for the periodically nanoscale patterned emitter Si solar cell.

The electro-optic mechanism and infrared switching dynamic of the hybrid multilayer VO2/Al:ZnO heterojunctions.

PubMed

Zhang, Peng; Zhang, Wu; Wang, Junyong; Jiang, Kai; Zhang, Jinzhong; Li, Wenwu; Wu, Jiada; Hu, Zhigao; Chu, Junhao

2017-06-30

Active and widely controllable phase transition optical materials have got rapid applications in energy-efficient electronic devices, field of meta-devices and so on. Here, we report the optical properties of the vanadium dioxide (VO 2 )/aluminum-doped zinc oxide (Al:ZnO) hybrid n-n type heterojunctions and the corresponding electro-optic performances of the devices. Various structures are fabricated to compare the discrepancy of the optical and electrical characteristics. It was found that the reflectance spectra presents the wheel phenomenon rather than increases monotonically with temperature at near-infrared region range. The strong interference effects was found in the hybrid multilayer heterojunction. In addition, the phase transition temperature decreases with increasing the number of the Al:ZnO layer, which can be ascribed to the electron injection to the VO 2 film from the Al:ZnO interface. Affected by the double layer Al:ZnO, the abnormal Raman vibration mode was presented in the insulator region. By adding the external voltage on the Al 2 O 3 /Al:ZnO/VO 2 /Al:ZnO, Al 2 O 3 /Al:ZnO/VO 2 and Al 2 O 3 /VO 2 /Al:ZnO thin-film devices, the infrared optical spectra of the devices can be real-time manipulated by an external voltage. The main effect of joule heating and assistant effect of electric field are illustrated in this work. It is believed that the results will add a more thorough understanding in the application of the VO 2 /transparent conductive film device.

Liquid crystal optics for communications, signal processing and 3-D microscopic imaging

NASA Astrophysics Data System (ADS)

Khan, Sajjad Ali

This dissertation proposes, studies and experimentally demonstrates novel liquid crystal (LC) optics to solve challenging problems in RF and photonic signal processing, freespace and fiber optic communications and microscopic imaging. These include free-space optical scanners for military and optical wireless applications, variable fiber-optic attenuators for optical communications, photonic control techniques for phased array antennas and radar, and 3-D microscopic imaging. At the heart of the applications demonstrated in this thesis are LC devices that are non-pixelated and can be controlled either electrically or optically. Instead of the typical pixel-by-pixel control as is custom in LC devices, the phase profile across the aperture of these novel LC devices is varied through the use of high impedance layers. Due to the presence of the high impedance layer, there forms a voltage gradient across the aperture of such a device which results in a phase gradient across the LC layer which in turn is accumulated by the optical beam traversing through this LC device. The geometry of the electrical contacts that are used to apply the external voltage will define the nature of the phase gradient present across the optical beam. In order to steer a laser beam in one angular dimension, straight line electrical contacts are used to form a one dimensional phase gradient while an annular electrical contact results in a circularly symmetric phase profile across the optical beam making it suitable for focusing the optical beam. The geometry of the electrical contacts alone is not sufficient to form the linear and the quadratic phase profiles that are required to either deflect or focus an optical beam. Clever use of the phase response of a typical nematic liquid crystal (NLC) is made such that the linear response region is used for the angular beam deflection while the high voltage quadratic response region is used for focusing the beam. Employing an NLC deflector, a device that uses the linear angular deflection, laser beam steering is demonstrated in two orthogonal dimensions whereas an NLC lens is used to address the third dimension to complete a three dimensional (3-D) scanner. Such an NLC deflector was then used in a variable optical attenuator (VOA), whereby a laser beam coupled between two identical single mode fibers (SMF) was mis-aligned away from the output fiber causing the intensity of the output coupled light to decrease as a function of the angular deflection. Since the angular deflection is electrically controlled, hence the VOA operation is fairly simple and repeatable. An extension of this VOA for wavelength tunable operation is also shown in this dissertation. (Abstract shortened by UMI.)

Incorporating an optical waveguide into a neural interface

DOEpatents

Tolosa, Vanessa; Delima, Terri L.; Felix, Sarah H.; Pannu, Satinderpall S.; Shah, Kedar G.; Sheth, Heeral; Tooker, Angela C.

2016-11-08

An optical waveguide integrated into a multielectrode array (MEA) neural interface includes a device body, at least one electrode in the device body, at least one electrically conducting lead coupled to the at least one electrode, at least one optical channel in the device body, and waveguide material in the at least one optical channel. The fabrication of a neural interface device includes the steps of providing a device body, providing at least one electrode in the device body, providing at least one electrically conducting lead coupled to the at least one electrode, providing at least one optical channel in the device body, and providing a waveguide material in the at least one optical channel.

Digital optical conversion module

DOEpatents

Kotter, D.K.; Rankin, R.A.

1988-07-19

A digital optical conversion module used to convert an analog signal to a computer compatible digital signal including a voltage-to-frequency converter, frequency offset response circuitry, and an electrical-to-optical converter. Also used in conjunction with the digital optical conversion module is an optical link and an interface at the computer for converting the optical signal back to an electrical signal. Suitable for use in hostile environments having high levels of electromagnetic interference, the conversion module retains high resolution of the analog signal while eliminating the potential for errors due to noise and interference. The module can be used to link analog output scientific equipment such as an electrometer used with a mass spectrometer to a computer. 2 figs.

Digital optical conversion module

DOEpatents

Kotter, Dale K.; Rankin, Richard A.

1991-02-26

A digital optical conversion module used to convert an analog signal to a computer compatible digital signal including a voltage-to-frequency converter, frequency offset response circuitry, and an electrical-to-optical converter. Also used in conjunction with the digital optical conversion module is an optical link and an interface at the computer for converting the optical signal back to an electrical signal. Suitable for use in hostile environments having high levels of electromagnetic interference, the conversion module retains high resolution of the analog signal while eliminating the potential for errors due to noise and interference. The module can be used to link analog output scientific equipment such as an electrometer used with a mass spectrometer to a computer.

Piezoelectric and optical setup to measure an electrical field: application to the longitudinal near-field generated by a tapered coax.

PubMed

Euphrasie, S; Vairac, P; Cretin, B; Lengaigne, G

2008-03-01

We propose a new setup to measure an electrical field in one direction. This setup is made of a piezoelectric sintered lead zinconate titanate film and an optical interferometric probe. We used this setup to investigate how the shape of the extremity of a coaxial cable influences the longitudinal electrical near-field generated by it. For this application, we designed our setup to have a spatial resolution of 100 microm in the direction of the electrical field. Simulations and experiments are presented.

Optical and Electric Multifunctional CMOS Image Sensors for On-Chip Biosensing Applications.

PubMed

Tokuda, Takashi; Noda, Toshihiko; Sasagawa, Kiyotaka; Ohta, Jun

2010-12-29

In this review, the concept, design, performance, and a functional demonstration of multifunctional complementary metal-oxide-semiconductor (CMOS) image sensors dedicated to on-chip biosensing applications are described. We developed a sensor architecture that allows flexible configuration of a sensing pixel array consisting of optical and electric sensing pixels, and designed multifunctional CMOS image sensors that can sense light intensity and electric potential or apply a voltage to an on-chip measurement target. We describe the sensors' architecture on the basis of the type of electric measurement or imaging functionalities.

Regression-Based Identification of Behavior-Encoding Neurons During Large-Scale Optical Imaging of Neural Activity at Cellular Resolution

PubMed Central

Miri, Andrew; Daie, Kayvon; Burdine, Rebecca D.; Aksay, Emre

2011-01-01

The advent of methods for optical imaging of large-scale neural activity at cellular resolution in behaving animals presents the problem of identifying behavior-encoding cells within the resulting image time series. Rapid and precise identification of cells with particular neural encoding would facilitate targeted activity measurements and perturbations useful in characterizing the operating principles of neural circuits. Here we report a regression-based approach to semiautomatically identify neurons that is based on the correlation of fluorescence time series with quantitative measurements of behavior. The approach is illustrated with a novel preparation allowing synchronous eye tracking and two-photon laser scanning fluorescence imaging of calcium changes in populations of hindbrain neurons during spontaneous eye movement in the larval zebrafish. Putative velocity-to-position oculomotor integrator neurons were identified that showed a broad spatial distribution and diversity of encoding. Optical identification of integrator neurons was confirmed with targeted loose-patch electrical recording and laser ablation. The general regression-based approach we demonstrate should be widely applicable to calcium imaging time series in behaving animals. PMID:21084686

Optogenetic versus electrical stimulation of dopamine terminals in the nucleus accumbens reveals local modulation of presynaptic release

PubMed Central

Melchior, James R.; Ferris, Mark J.; Stuber, Garret D.; Riddle, David R.; Jones, Sara R.

2015-01-01

The nucleus accumbens is highly heterogeneous, integrating regionally distinct afferent projections and accumbal interneurons, resulting in diverse local microenvironments. Dopamine (DA) neuron terminals similarly express a heterogeneous collection of terminal receptors that modulate DA signaling. Cyclic voltammetry is often used to probe DA terminal dynamics in brain slice preparations; however, this method traditionally requires electrical stimulation to induce DA release. Electrical stimulation excites all of the neuronal processes in the stimulation field, potentially introducing simultaneous, multi-synaptic modulation of DA terminal release. We used optogenetics to selectively stimulate DA terminals and used voltammetry to compare DA responses from electrical and optical stimulation of the same area of tissue around a recording electrode. We found that with multiple pulse stimulation trains, optically stimulated DA release increasingly exceeded that of electrical stimulation. Furthermore, electrical stimulation produced inhibition of DA release across longer duration stimulations. The GABAB antagonist, CGP 55845, increased electrically stimulated DA release significantly more than light stimulated release. The nicotinic acetylcholine receptor antagonist, dihydro-β-erythroidine hydrobromide, inhibited single pulse electrically stimulated DA release while having no effect on optically stimulated DA release. Our results demonstrate that electrical stimulation introduces local multi-synaptic modulation of DA release that is absent with optogenetically targeted stimulation. PMID:26011081

Defect structure of web silicon ribbon

NASA Technical Reports Server (NTRS)

Cunningham, B.; Strunk, H.; Ast, D.

1980-01-01

The results of a preliminary study of two dendritic web samples are presented. The structure and electrical activity of the defects in the silicon webs were studied. Optical microscopy of chemically etched specimens was used to determine dislocation densities. Samples were mechanically polished, then Secco etched for approximately 5 minutes. High voltage transmission electron microscopy was used to characterize the crystallographic nature of the defects.

Optically Active Plasmonic Metasurfaces based on the Hybridization of In-Plane Coupling and Out-of-Plane Coupling.

PubMed

Wu, Dong; Yang, Liu; Liu, Chang; Xu, Zenghui; Liu, Yumin; Yu, Zhongyuan; Yu, Li; Chen, Lei; Ma, Rui; Ye, Han

2018-05-10

Plasmonic metasurfaces have attracted much attention in recent years owing to many promising prospects of applications such as polarization switching, local electric field enhancement (FE), near-perfect absorption, sensing, slow-light devices, and nanoantennas. However, many problems in these applications, like only gigahertz switching speeds of electro-optical switches, low-quality factor (Q) of plasmonic resonances, and relatively low figure of merit (FOM) of sensing, severely limit the further development of plasmonic metasurface. Besides, working as nanoantennas, it is also challenging to realize both local electric FE exceeding 100 and near-perfect absorption above 99%. Here, using finite element method and finite difference time domain methods respectively, we firstly report a novel optically tunable plasmonic metasurface based on the hybridization of in-plane near-field coupling and out-of-plane near-field coupling, which provides a good solution to these serious and urgent problems. A physical phenomenon of electromagnetically induced transparency is obtained by the destructive interference between two plasmon modes. At the same time, ultrasharp perfect absorption peaks with ultra-high Q-factor (221.43) is achieved around 1550 nm, which can lead to an ultra-high FOM (214.29) in sensing application. Particularly, by using indium-doped CdO, this metasurface is also firstly demonstrated to be a femtosecond optical reflective polarizer in near-infrared region, possessing an ultra-high polarization extinction ratio. Meanwhile, operating as nanoantennas, this metasurface achieves simultaneously strong local electric FE(|E loc |/|E 0 | > 100) and a near-perfect absorption above 99.9% for the first time, which will benefit a wide range of applications including photocatalytic water splitting and surface-enhanced infrared absorption.

Optically Active Plasmonic Metasurfaces based on the Hybridization of In-Plane Coupling and Out-of-Plane Coupling

NASA Astrophysics Data System (ADS)

Wu, Dong; Yang, Liu; Liu, Chang; Xu, Zenghui; Liu, Yumin; Yu, Zhongyuan; Yu, Li; Chen, Lei; Ma, Rui; Ye, Han

2018-05-01

Plasmonic metasurfaces have attracted much attention in recent years owing to many promising prospects of applications such as polarization switching, local electric field enhancement (FE), near-perfect absorption, sensing, slow-light devices, and nanoantennas. However, many problems in these applications, like only gigahertz switching speeds of electro-optical switches, low-quality factor (Q) of plasmonic resonances, and relatively low figure of merit (FOM) of sensing, severely limit the further development of plasmonic metasurface. Besides, working as nanoantennas, it is also challenging to realize both local electric FE exceeding 100 and near-perfect absorption above 99%. Here, using finite element method and finite difference time domain methods respectively, we firstly report a novel optically tunable plasmonic metasurface based on the hybridization of in-plane near-field coupling and out-of-plane near-field coupling, which provides a good solution to these serious and urgent problems. A physical phenomenon of electromagnetically induced transparency is obtained by the destructive interference between two plasmon modes. At the same time, ultrasharp perfect absorption peaks with ultra-high Q-factor (221.43) is achieved around 1550 nm, which can lead to an ultra-high FOM (214.29) in sensing application. Particularly, by using indium-doped CdO, this metasurface is also firstly demonstrated to be a femtosecond optical reflective polarizer in near-infrared region, possessing an ultra-high polarization extinction ratio. Meanwhile, operating as nanoantennas, this metasurface achieves simultaneously strong local electric FE(| E loc|/| E 0| > 100) and a near-perfect absorption above 99.9% for the first time, which will benefit a wide range of applications including photocatalytic water splitting and surface-enhanced infrared absorption.

Manipulation of surface plasmon resonance of a graphene-based Au aperture antenna in visible and near-infrared regions

NASA Astrophysics Data System (ADS)

Wan, Yuan; An, Yashuai; Tao, Zhi; Deng, Luogen

2018-03-01

Behaviors of surface plasmon resonance (SPR) of a graphene-based Au aperture antenna are investigated in visible and near-infrared (vis-NIR) regions. Compared with the SPR wavelength of a traditional Au aperture antenna, the SPR wavelength of the graphene-based Au aperture antenna shows a remarkable blue shift due to the redistribution of the electric field in the proposed structure. The electric field of the graphene-based Au aperture antenna is highly localized on the surface of the graphene in the aperture and redistributed to be a standing wave. Moreover, the SPR of a graphene-based Au aperture antenna is sensitive to the thickness and the refractive index of the dielectric layer, the graphene Fermi energy, the refractive index of the environment and the polarization direction of the incident light. Finally, we find the wavelength, intensity and phase of the reflected light of the graphene-based Au aperture antenna array can be actively modulated by varying the graphene Fermi energy. The proposed structure provides a promising platform for realizing a tunable optical filter, a highly sensitive refractive index sensor, and other actively tunable optical and optoelectronic devices.

Using affordable LED arrays for photo-stimulation of neurons.

PubMed

Valley, Matthew; Wagner, Sebastian; Gallarda, Benjamin W; Lledo, Pierre-Marie

2011-11-15

Standard slice electrophysiology has allowed researchers to probe individual components of neural circuitry by recording electrical responses of single cells in response to electrical or pharmacological manipulations(1,2). With the invention of methods to optically control genetically targeted neurons (optogenetics), researchers now have an unprecedented level of control over specific groups of neurons in the standard slice preparation. In particular, photosensitive channel rhodopsin-2 (ChR2) allows researchers to activate neurons with light(3,4). By combining careful calibration of LED-based photostimulation of ChR2 with standard slice electrophysiology, we are able to probe with greater detail the role of adult-born interneurons in the olfactory bulb, the first central relay of the olfactory system. Using viral expression of ChR2-YFP specifically in adult-born neurons, we can selectively control young adult-born neurons in a milieu of older and mature neurons. Our optical control uses a simple and inexpensive LED system, and we show how this system can be calibrated to understand how much light is needed to evoke spiking activity in single neurons. Hence, brief flashes of blue light can remotely control the firing pattern of ChR2-transduced newborn cells.

Quantitative optical scanning tests of complex microcircuits

NASA Technical Reports Server (NTRS)

Erickson, J. J.

1980-01-01

An approach for the development of the optical scanner as a screening inspection instrument for microcircuits involves comparing the quantitative differences in photoresponse images and then correlating them with electrical parameter differences in test devices. The existing optical scanner was modified so that the photoresponse data could be recorded and subsequently digitized. A method was devised for applying digital image processing techniques to the digitized photoresponse data in order to quantitatively compare the data. Electrical tests were performed and photoresponse images were recorded before and following life test intervals on two groups of test devices. Correlations were made between differences or changes in the electrical parameters of the test devices.

An opto-electro-mechanical system based on evanescently-coupled optical microbottle and electromechanical resonator

NASA Astrophysics Data System (ADS)

Asano, Motoki; Ohta, Ryuichi; Yamamoto, Takashi; Okamoto, Hajime; Yamaguchi, Hiroshi

2018-05-01

Evanescent coupling between a high-Q silica optical microbottle and a GaAs electromechanical resonator is demonstrated. This coupling offers an opto-electro-mechanical system which possesses both cavity-enhanced optical sensitivity and electrical controllability of the mechanical motion. Cooling and heating of the mechanical mode are demonstrated based on optomechanical detection via the radiation pressure and electromechanical feedback via the piezoelectric effect. This evanescent approach allows for individual design of optical, mechanical, and electrical systems, which could lead to highly sensitive and functionalized opto-electro-mechanical systems.

Effects of electromagnetic fields on the nonlinear optical properties of asymmetric double quantum well under intense laser field

NASA Astrophysics Data System (ADS)

Yesilgul, U.; Sari, H.; Ungan, F.; Martínez-Orozco, J. C.; Restrepo, R. L.; Mora-Ramos, M. E.; Duque, C. A.; Sökmen, I.

2017-03-01

In this study, the effects of electric and magnetic fields on the optical rectification and second and third harmonic generation in asymmetric double quantum well under the intense non-resonant laser field is theoretically investigated. We calculate the optical rectification and second and third harmonic generation within the compact density-matrix approach. The theoretical findings show that the influence of electric, magnetic, and intense laser fields leads to significant changes in the coefficients of nonlinear optical rectification, second and third harmonic generation.

Lightweight fiber optic microphones and accelerometers

NASA Astrophysics Data System (ADS)

Bucaro, J. A.; Lagakos, N.

2001-06-01

We have designed, fabricated, and tested two lightweight fiber optic sensors for the dynamic measurement of acoustic pressure and acceleration. These sensors, one a microphone and the other an accelerometer, are required for active blanket sound control technology under development in our laboratory. The sensors were designed to perform to certain specifications dictated by our active sound control application and to do so without exhibiting sensitivity to the high electrical voltages expected to be present. Furthermore, the devices had to be small (volumes less than 1.5 cm3) and light (less than 2 g). To achieve these design criteria, we modified and extended fiber optic reflection microphone and fiber microbend displacement device designs reported in the literature. After fabrication, the performances of each sensor type were determined from measurements made in a dynamic pressure calibrator and on a shaker table. The fiber optic microbend accelerometer, which weighs less than 1.8 g, was found to meet all performance goals including 1% linearity, 90 dB dynamic range, and a minimum detectable acceleration of 0.2 mg/√Hz . The fiber optic microphone, which weighs less than 1.3 g, also met all goals including 1% linearity, 85 dB dynamic range, and a minimum detectable acoustic pressure level of 0.016 Pa/√Hz . In addition to our specific use in active sound control, these sensors appear to have application in a variety of other areas.

Shielded Coaxial Optrode Arrays for Neurophysiology

PubMed Central

Naughton, Jeffrey R.; Connolly, Timothy; Varela, Juan A.; Lundberg, Jaclyn; Burns, Michael J.; Chiles, Thomas C.; Christianson, John P.; Naughton, Michael J.

2016-01-01

Recent progress in the study of the brain has been greatly facilitated by the development of new tools capable of minimally-invasive, robust coupling to neuronal assemblies. Two prominent examples are the microelectrode array (MEA), which enables electrical signals from large numbers of neurons to be detected and spatiotemporally correlated, and optogenetics, which enables the electrical activity of cells to be controlled with light. In the former case, high spatial density is desirable but, as electrode arrays evolve toward higher density and thus smaller pitch, electrical crosstalk increases. In the latter, finer control over light input is desirable, to enable improved studies of neuroelectronic pathways emanating from specific cell stimulation. Here, we introduce a coaxial electrode architecture that is uniquely suited to address these issues, as it can simultaneously be utilized as an optical waveguide and a shielded electrode in dense arrays. Using optogenetically-transfected cells on a coaxial MEA, we demonstrate the utility of the architecture by recording cellular currents evoked from optical stimulation. We also show the capability for network recording by radiating an area of seven individually-addressed coaxial electrode regions with cultured cells covering a section of the extent. PMID:27375415

Activation and control of microlens liquid arrays on functionalized polar electric crystal substrates by electro-wetting effect and temperature

NASA Astrophysics Data System (ADS)

Ferraro, Pietro; Grilli, Simonetta; Miccio, Lisa; Vespini, Veronica; Finizio, Sergio DeNicola Andrea

2008-11-01

In recent years a variety of liquid bases optical elements have been conceived, designed and fabricated even for commercial products like digital cameras o cellular phone cameras. The impressive development of microfluidic systems in conjunction with optics has led to the creation of a completely new Science field of investigation named optofludics. Optofludics, among others topics, deals with investigation and methods for realizing liquid micro-lenses. A variety of liquid micro-lenses have been designed and realized by using different configurations. We demonstrate that a lensing effect can be obtained in an open microfluidic system by using a thin layer of liquid on a polar electric crystal such as Lithium Niobate (LiNbO3). Electrowetting patterning on LiNbO3 surface is obtained by pyroelectric effect consisting in a simple but reliable electrodes-less and circuit-less configuration. The electrodes are intrinsically embedded into the substrate. The material is functionalised by means of a micro-engineering electric filed poling process. Lens array with variable focus has been demonstrated with a large number of lens elements (10x10) on micrometric scale (aperture of single lens 100 microns).

Influence of p-GaN annealing on the optical and electrical properties of InGaN/GaN MQW LEDs

NASA Astrophysics Data System (ADS)

Sun, Li; Weng, Guo-En; Liang, Ming-Ming; Ying, Lei-Ying; Lv, Xue-Qin; Zhang, Jiang-Yong; Zhang, Bao-Ping

2014-06-01

Optical and electrical properties of InGaN/GaN multiple quantum wells (MQWs) light emitting diodes (LEDs) annealed in pure O2 ambient (500 °C) and pure N2 ambient (800 °C) were systematically investigated. The temperature-dependent photoluminescence measurements showed that high-temperature thermal annealing in N2 ambient can induce indium clusters in InGaN MQWs. Although the deep traps induced by indium clusters can act as localized centers for carriers, there are many more dislocations out of the trap centers due to high-temperature annealing. As a result, the radiative efficiency of the sample annealed in N2 ambient was lower than that annealed in O2 ambient at room temperature. Electrical measurements demonstrated that the LEDs annealed in O2 ambient were featured by a lower forward voltage and there was an increase of ~41% in wall-plug efficiency at 20 mA in comparison with the LEDs annealed in N2 ambient. It is thus concluded that activation of the Mg-doped p-GaN layer should be carried out at a low-temperature O2 ambient so as to obtain LEDs with better performance.

Systems special investigation group

NASA Technical Reports Server (NTRS)

1991-01-01

An interim report concerning the Long Duration Exposure Facility (LDEF) is presented by a Boeing Systems special investigation group (SIG). The SIG activities were divided into five engineering disciplines: electrical, mechanical, optics, thermal, and batteries/solar cells. The responsibilities of the SIG included the following areas: support de-integration at Kennedy Space Center (KSC); testing of hardware at Boeing; review of principal investigator (PI) test plans and test results; support of test activities at PI labs; and collation of all test results into the SIG database.

Incidence, hemodynamic, and electrical characteristics of spreading depolarization in a swine model are affected by local but not by intravenous application of magnesium.

PubMed

Santos, Edgar; León, Fiorella; Silos, Humberto; Sanchez-Porras, Renan; Shuttleworth, C William; Unterberg, Andreas; Sakowitz, Oliver W

2016-12-01

The aim was to characterize the effects of magnesium sulfate, using i.v. bolus and local administration, using intrinsic signal imaging, and on electrocorticographic activity during the induction and propagation of spreading depolarizations in the gyrencephalic porcine brain. Local application of magnesium sulfate led to a complete inhibition of spreading depolarizations. One hour after washing out the topical magnesium sulfate, re-incidence of the spreading depolarizations was observed in 50% of the hemispheres. Those spreading depolarizations showed attenuation in hemodynamic characteristics and speed in intrinsic optical signal imaging. The electrical amplitude decreased through electrocorticographic activity. Intravenous magnesium therapy showed no significant effects on spreading depolarization incidence and characteristics. © The Author(s) 2016.

Electrical tuning of the oscillator strength in type II InAs/GaInSb quantum wells for active region of passively mode-locked interband cascade lasers

NASA Astrophysics Data System (ADS)

Dyksik, Mateusz; Motyka, Marcin; Kurka, Marcin; Ryczko, Krzysztof; Misiewicz, Jan; Schade, Anne; Kamp, Martin; Höfling, Sven; Sęk, Grzegorz

2017-11-01

Two designs of active region for an interband cascade laser, based on double or triple GaInSb/InAs type II quantum wells (QWs), were compared with respect to passive mode-locked operation in the mid-infrared range around 4 µm. The layer structure and electron and hole wavefunctions under external electric field were engineered to allow controlling the optical transition oscillator strength and the resulting lifetimes. As a result, the investigated structures can mimic absorber-like and gain-like sections of a mode-locked device when properly polarized with opposite bias. A significantly larger oscillator strength tuning range for triple QWs was experimentally verified by Fourier-transform photoreflectance.

Single crystal diamond membranes for nanoelectronics.

PubMed

Bray, Kerem; Kato, Hiromitsu; Previdi, Rodolfo; Sandstrom, Russell; Ganesan, Kumaravelu; Ogura, Masahiko; Makino, Toshiharu; Yamasaki, Satoshi; Magyar, Andrew P; Toth, Milos; Aharonovich, Igor

2018-02-22

Single crystal, nanoscale diamond membranes are highly sought after for a variety of applications including nanophotonics, nanoelectronics and quantum information science. However, so far, the availability of conductive diamond membranes has remained an unreachable goal. In this work we present a complete nanofabrication methodology for engineering high aspect ratio, electrically active single crystal diamond membranes. The membranes have large lateral directions, exceeding ∼500 × 500 μm 2 and are only several hundreds of nanometers thick. We further realize vertical single crystal p-n junctions made from the diamond membranes that exhibit onset voltages of ∼10 V and a current of several mA. Moreover, we deterministically introduce optically active color centers into the membranes, and demonstrate for the first time a single crystal nanoscale diamond LED. The robust and scalable approach to engineer the electrically active single crystal diamond membranes offers new pathways for advanced nanophotonic, nanoelectronic and optomechanical devices employing diamond.

Coupled optical and electrical study of thin-film InGaAs photodetector integrated with surface InP Mie resonators

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fu, Dong; Song, Jiakun; Yu, Hailong

2016-03-14

High-index dielectric and semiconductor nanostructures with characteristics of low absorption loss and artificially controlled scattering properties have grasped an increasing attention for improving the performance of thin-film photovoltaic devices. In this work, combined optical and electrical simulations were performed for thin-film InP/In{sub 0.53}Ga{sub 0.47}As/InP hetero-junction photodetector with periodically arranged InP nano-cylinders in the in-coupling configuration. It is found that the carefully designed InP nano-cylinders possess strongly substrate-coupled Mie resonances and can effectively couple incident light into the guided mode, both of which significantly increase optical absorption. Further study from the electrical aspects shows that enhancement of external quantum efficiency ismore » as high as 82% and 83% in the configurations with the optimized nano-cylinders and the optimized period, respectively. Moreover, we demonstrate that the integration of InP nano-cylinders does not degrade the electrical performance, since the surface recombination is effectively suppressed by separating the absorber layer where carriers generate and the air/semiconductor interface. The comprehensive modeling including optical and electrical perspectives provides a more practical description for device performance than the optical-only simulation and is expected to advance the design of thin-film absorber layer based optoelectronic devices for fast response and high efficiency.« less

Electrical and optical transport properties of single layer WSe2

NASA Astrophysics Data System (ADS)

Tahir, M.

2018-03-01

The electronic properties of single layer WSe2 are distinct from the famous graphene due to strong spin orbit coupling, a huge band gap and an anisotropic lifting of the degeneracy of the valley degree of freedom under Zeeman field. In this work, band structure of the monolayer WSe2 is evaluated in the presence of spin and valley Zeeman fields to study the electrical and optical transport properties. Using Kubo formalism, an explicit expression for the electrical Hall conductivity is examined at finite temperatures. The electrical longitudinal conductivity is also evaluated. Further, the longitudinal and Hall optical conductivities are analyzed. It is observed that the contributions of the spin-up and spin-down states to the power absorption spectrum depend on the valley index. The numerical results exhibit absorption peaks as a function of photon energy, ℏ ω, in the range ∼ 1.5 -2 eV. Also, the optical response lies in the visible frequency range in contrast to the conventional two-dimensional electron gas or graphene where the response is limited to terahertz regime. This ability to isolate carriers in spin-valley coupled structures may make WSe2 a promising candidate for future spintronics, valleytronics and optical devices.

Donor impurity-related linear and nonlinear intraband optical absorption coefficients in quantum ring: effects of applied electric field and hydrostatic pressure

PubMed Central

2012-01-01

The linear and nonlinear intraband optical absorption coefficients in GaAs three-dimensional single quantum rings are investigated. Taking into account the combined effects of hydrostatic pressure and electric field, applied along the growth direction of the heterostructure, the energies of the ground and first excited states of a donor impurity have been found using the effective mass approximation and a variational method. The energies of these states are examined as functions of the dimensions of the structure, electric field, and hydrostatic pressure. We have also investigated the dependencies of the linear, nonlinear, and total optical absorption coefficients as a function of incident photon energy for several configurations of the system. It is found that the variation of distinct sizes of the structure leads to either a redshift and/or a blueshift of the resonant peaks of the intraband optical spectrum. In addition, we have found that the application of an electric field leads to a redshift, whereas the influence of hydrostatic pressure leads to a blueshift (in the case of on-ring-center donor impurity position) of the resonant peaks of the intraband optical spectrum. PMID:23021497

A theoretical study of molecular structure, optical properties and bond activation of energetic compound FOX-7 under intense electric fields

NASA Astrophysics Data System (ADS)

Tao, Zhiqiang; Wang, Xin; Wei, Yuan; Lv, Li; Wu, Deyin; Yang, Mingli

2017-02-01

Molecular structure, vibrational and electronic absorption spectra, chemical reactivity of energetic compound FOX-7, one of the most widely used explosives, were studied computationally in presence of an electrostatic field of 0.01-0.05 a.u. The Csbnd N bond, which usually triggers the decomposition of FOX-7, is shortened/elongated under a parallel/antiparallel field. The Csbnd N bond activation energy varies with the external electric field, decreasing remarkably with the field strength in regardless of the field direction. This is attributed to two aspects: the bond weakening by the field parallel to the Csbnd N bond and the stabilization effect on the transition-state structure by the field antiparallel to the bond. The variations in the structure and property of FOX-7 under the electric fields were further analyzed with its distributional polarizability, which is dependent on the charge transfer characteristics through the Csbnd N bond.

Nanophotonic Devices; Spontaneous Emission Faster than Stimulated Emission

DTIC Science & Technology

2016-02-02

optically pumped spontaneous emission, and electrically pumped spontaneous emission. We have observed a speedup of >300x, and we project a speedup of 2500x...The project has succeeded, both for optically pumped spontaneous emission, and electrically pumped spontaneous emission. We have observed a speedup...Fabricated Plasmonic Optical Transformer”, (with H. Choo, S. Cabrini, P.J. Schuck, X. Liang,) U.S. Patent No. 9,052,450 (Jun. 9, 2015). 2. “ Probes

Linear Self-Referencing Techiques for Short-Optical-Pulse Characterization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dorrer, C.; Kang, I.

2008-04-04

Linear self-referencing techniques for the characterization of the electric field of short optical pulses are presented. The theoretical and practical advantages of these techniques are developed. Experimental implementations are described, and their performance is compared to the performance of their nonlinear counterparts. Linear techniques demonstrate unprecedented sensitivity and are a perfect fit in many domains where the precise, accurate measurement of the electric field of an optical pulse is required.

Modulation and detection of single neuron activity using spin transfer nano-oscillators

NASA Astrophysics Data System (ADS)

Algarin, Jose Miguel; Ramaswamy, Bharath; Venuti, Lucy; Swierzbinski, Matthew; Villar, Pablo; Chen, Yu-Jin; Krivorotov, Ilya; Weinberg, Irving N.; Herberholz, Jens; Araneda, Ricardo; Shapiro, Benjamin; Waks, Edo

2017-09-01

The brain is a complex network of interconnected circuits that exchange electrical signals with each other. These electrical signals provide insight on how neural circuits code information, and give rise to sensations, thoughts, emotions and actions. Currents methods to detect and modulate these electrical signals use implanted electrodes or optical fields with light sensitive dyes in the brain. These techniques require complex surgeries or suffer low resolution. In this talk we explore a new method to both image and stimulate single neurons using spintronics. We propose using a Spin Transfer Nano-Oscillators (STNOs) as a nanoscale sensor that converts neuronal action potentials to microwave field oscillations that can be detected wirelessly by magnetic induction. We will describe our recent proof-of-concept demonstration of both detection and wireless modulation of neuronal activity using STNOs. For detection we use electrodes to connect a STNO to a lateral giant crayfish neuron. When we stimulate the neuron, the STNO responds to the neuronal activity with a corresponding microwave signal. For modulation, we stimulate the STNOs wirelessly using an inductively coupled solenoid. The STNO rectifies the induced microwave signal to produce a direct voltage. This direct voltage from the STNO, when applied in the vicinity of a mammalian neuron, changes the frequency of electrical signals produced by the neuron.

Method for surface plasmon amplification by stimulated emission of radiation (SPASER)

DOEpatents

Stockman, Mark I [Atlanta, GA; Bergman, David J [Ramat Hasharon, IL

2011-09-13

A nanostructure is used to generate a highly localized nanoscale optical field. The field is excited using surface plasmon amplification by stimulated emission of radiation (SPASER). The SPASER radiation consists of surface plasmons that undergo stimulated emission, but in contrast to photons can be localized within a nanoscale region. A SPASER can incorporate an active medium formed by two-level emitters, excited by an energy source, such as an optical, electrical, or chemical energy source. The active medium may be quantum dots, which transfer excitation energy by radiationless transitions to a resonant nanosystem that can play the same role as a laser cavity in a conventional laser. The transitions are stimulated by the surface plasmons in the nanostructure, causing the buildup of a macroscopic number of surface plasmons in a single mode.

Surface plasmon amplification by stimulated emission of radiation (SPASER)

DOEpatents

Stockman, Mark I [Atlanta, GA; Bergman, David J [Ramat Hasharon, IL

2009-08-04

A nanostructure is used to generate a highly localized nanoscale optical field. The field is excited using surface plasmon amplification by stimulated emission of radiation (SPASER). The SPASER radiation consists of surface plasmons that undergo stimulated emission, but in contrast to photons can be localized within a nanoscale region. A SPASER can incorporate an active medium formed by two-level emitters, excited by an energy source, such as an optical, electrical, or chemical energy source. The active medium may be quantum dots, which transfer excitation energy by radiationless transitions to a resonant nanosystem that can play the same role as a laser cavity in a conventional laser. The transitions are stimulated by the surface plasmons in the nanostructure, causing the buildup of a macroscopic number of surface plasmons in a single mode.

Transparent active matrix organic light-emitting diode displays driven by nanowire transistor circuitry.

PubMed

Ju, Sanghyun; Li, Jianfeng; Liu, Jun; Chen, Po-Chiang; Ha, Young-Geun; Ishikawa, Fumiaki; Chang, Hsiaokang; Zhou, Chongwu; Facchetti, Antonio; Janes, David B; Marks, Tobin J

2008-04-01

Optically transparent, mechanically flexible displays are attractive for next-generation visual technologies and portable electronics. In principle, organic light-emitting diodes (OLEDs) satisfy key requirements for this application-transparency, lightweight, flexibility, and low-temperature fabrication. However, to realize transparent, flexible active-matrix OLED (AMOLED) displays requires suitable thin-film transistor (TFT) drive electronics. Nanowire transistors (NWTs) are ideal candidates for this role due to their outstanding electrical characteristics, potential for compact size, fast switching, low-temperature fabrication, and transparency. Here we report the first demonstration of AMOLED displays driven exclusively by NW electronics and show that such displays can be optically transparent. The displays use pixel dimensions suitable for hand-held applications, exhibit 300 cd/m2 brightness, and are fabricated at temperatures suitable for integration on plastic substrates.

Brain machine interfaces combining microelectrode arrays with nanostructured optical biochemical sensors

NASA Astrophysics Data System (ADS)

Hajj-Hassan, Mohamad; Gonzalez, Timothy; Ghafer-Zadeh, Ebrahim; Chodavarapu, Vamsy; Musallam, Sam; Andrews, Mark

2009-02-01

Neural microelectrodes are an important component of neural prosthetic systems which assist paralyzed patients by allowing them to operate computers or robots using their neural activity. These microelectrodes are also used in clinical settings to localize the locus of seizure initiation in epilepsy or to stimulate sub-cortical structures in patients with Parkinson's disease. In neural prosthetic systems, implanted microelectrodes record the electrical potential generated by specific thoughts and relay the signals to algorithms trained to interpret these thoughts. In this paper, we describe novel elongated multi-site neural electrodes that can record electrical signals and specific neural biomarkers and that can reach depths greater than 8mm in the sulcus of non-human primates (monkeys). We hypothesize that additional signals recorded by the multimodal probes will increase the information yield when compared to standard probes that record just electropotentials. We describe integration of optical biochemical sensors with neural microelectrodes. The sensors are made using sol-gel derived xerogel thin films that encapsulate specific biomarker responsive luminophores in their nanostructured pores. The desired neural biomarkers are O2, pH, K+, and Na+ ions. As a prototype, we demonstrate direct-write patterning to create oxygen-responsive xerogel waveguide structures on the neural microelectrodes. The recording of neural biomarkers along with electrical activity could help the development of intelligent and more userfriendly neural prosthesis/brain machine interfaces as well as aid in providing answers to complex brain diseases and disorders.

Optimal integration of daylighting and electric lighting systems using non-imaging optics

NASA Astrophysics Data System (ADS)

Scartezzini, J.-L.; Linhart, F.; Kaegi-Kolisnychenko, E.

2007-09-01

Electric lighting is responsible for a significant fraction of electricity consumption within non-residential buildings. Making daylight more available in office and commercial buildings can lead as a consequence to important electricity savings, as well as to the improvement of occupants' visual performance and wellbeing. Over the last decades, daylighting technologies have been developed for that purpose, some of them having proven to be highly efficient such as anidolic daylighting systems. Based on non-imaging optics these optical devices were designed to achieve an efficient collection and redistribution of daylight within deep office rooms. However in order to benefit from the substantial daylight provision obtained through these systems and convert it into effective electricity savings, novel electric lighting strategies are required. An optimal integration of high efficacy light sources and efficient luminaries based on non-imaging optics with anidolic daylighting systems can lead to such novel strategies. Starting from the experience gained through the development of an Anidolic Integrated Ceiling (AIC), this paper presents an optimal integrated daylighting and electric lighting system. Computer simulations based on ray-tracing techniques were used to achieve the integration of 36W fluorescent tubes and non-imaging reflectors with an advanced daylighting system. Lighting power densities lower than 4 W/m2 can be achieved in this way within the corresponding office room. On-site monitoring of an integrated daylighting and electric lighting system carried out on a solar experimental building confirmed the energy and visual performance of such a system: it showed that low lighting power densities can be achieved by combining an anidolic daylighting system with very efficient electric light sources and luminaries.

MUSIC for localization of thunderstorm cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mosher, J.C.; Lewis, P.S.; Rynne, T.M.

1993-12-31

Lightning represents an event detectable optically, electrically, and acoustically, and several systems are already in place to monitor such activity. Unfortunately, such detection of lightning can occur too late, since operations need to be protected in advance of the first lightning strike. Additionally, the bolt itself can traverse several kilometers before striking the ground, leaving a large region of uncertainty as to the center of the storm and its possible strike regions. NASA Kennedy Space Center has in place an array of electric field mills that monitor the (effectively) DC electric field. Prior to the first lightning strike, the surfacemore » electric fields rise as the storm generator within a thundercloud begins charging. Extending methods we developed for an analogous source localization problem in mangnetoencephalography, we present Cramer-Rao lower bounds and MUSIC scans for fitting a point-charge source model to the electric field mill data. Such techniques can allow for the identification and localization of charge centers in cloud structures.« less

Joint electrical engineering/physics course sequence for optics fundamentals and design

NASA Astrophysics Data System (ADS)

Magnusson, Robert; Maldonado, Theresa A.; Black, Truman D.

2000-06-01

Optics is a key technology in a broad range of engineering and science applications of high national priority. Engineers and scientists with a sound background in this field are needed to preserve technical leadership and to establish new directions of research and development. To meet this educational need, a joint Electrical Engineering/Physics optics course sequence was created as PHYS 3445 Fundamentals of Optics and EE 4444 Optical Systems Design, both with a laboratory component. The objectives are to educate EE and Physics undergraduate students in the fundamentals of optics; in interdisciplinary problem solving; in design and analysis; in handling optical components; and in skills such as communications and team cooperation. Written technical reports in professional format are required, formal presentations are given, and participation in paper design contests is encouraged.

Optically-energized, emp-resistant, fast-acting, explosion initiating device

DOEpatents

Benson, David A.; Kuswa, Glenn W.

1987-01-01

Optical energy, provided from a remote user-operated source, is utilized to initially electrically charge a capacitor in a circuit that also contains an explosion initiating transducer in contact with a small explosive train contained in an attachable housing. Additional optical energy is subsequently supplied in a preferred embodiment to an optically responsive phototransistor acting in conjunction with a silicon controlled rectifer to release the stored electrical energy through the explosion initiating transducer to set off the explosive train. All energy transfers between the user and the explosive apparatus, either for charging it up or for setting it off, are conveyed optically and may be accomplished in a single optical fiber with coding to distinguish between specific optical energy transfers and between these and any extraneous signals.

A review of optical pacing with infrared light

NASA Astrophysics Data System (ADS)

Ford, S. M.; Watanabe, M.; Jenkins, M. W.

2018-02-01

Optical pacing (OP) uses pulsed infrared light to initiate heartbeats in electrically excitable cardiac tissues without employing exogenous agents. OP is an alternative approach to electrical pacing that may overcome some its disadvantages for some applications. In this review, we discuss the initial demonstrations, mechanisms, safety, advantages and applications of OP.

Electric field effects on the optical properties of buckled GaAs monolayer

NASA Astrophysics Data System (ADS)

Bahuguna, Bhagwati Prasad; Saini, L. K.; Sharma, Rajesh O.

2018-04-01

Buckled GaAs monolayer has a direct band gap semiconductor with energy gap of 1.31 eV in the absence of electric field. When we applied transverse electric field, the value of band gap decreases with increasing of electric field strength. In our previous work [1], it is observed that the buckled GaAs monolayer becomes metallic at 1.3 V/Å. In the present work, we investigate the optical properties such as photon energy-dependent dielectric functions, extinction coefficient, refractive index, absorption spectrum and reflectivity of buckled GaAs monolayer in the semiconducting phase i.e. absence of external electric field and metallic phase i.e. presence of external electric field using density functional theory.

A sensor for vector electric field measurements through a nonlinear anisotropic optical crystal

NASA Astrophysics Data System (ADS)

Barbieri, Luca; Gondola, Marco; Potenza, Marco; Villa, Andrea; Malgesini, Roberto

2017-11-01

Electrical applications require the development of electric field sensors that can reproduce vector electric field waveforms with a very large spectral width ranging from 50 Hz to at least 70 MHz. This makes it possible to measure both the normal operation modes of electrical components and abnormal behaviors such as the corona emission and partial discharges. In this work, we aim to develop a fully dielectric sensor capable of measuring two components of the electric field using a wide class of optical crystals including anisotropic ones, whereas most of the efforts in this field have been devoted to isotropic crystals. We report the results of the measurements performed at 50 Hz and with a lightning impulse, to validate the sensor.

11th International Conference "Correlation Optics": Propolis films for hybrid biomaterial-inorganic electronics and optoelectronics.

PubMed

Brus, Viktor V; Pidkamin, Leonid J; Ilashchuk, Maria I; Maryanchuk, Pavlo D

2014-04-01

We report on the analysis of optical, polarimetric, and electrical properties of propolis films and hybrid biomaterial-inorganic heterojunctions based on them. It was shown that the material of the propolis films belongs to wide-bandgap optically active substances with the light-scattering centers, which possess complex optical properties. The values of the specific resistance ρ(P)=1.9·10⁷ Ω·cm and dielectric constant ε(P)=19.5 of the propolis film were determined from the spectral distribution of the real and imaginary components of its impedance at room temperature, respectively. The dominating current transport mechanisms through the hybrid bioinorganic heterojunction propolis/p-CdTe were established to be the interface-states-assisted generation-recombination within the depletion region via deep energy levels at forward bias as well as the leakage current through the shunt resistance at reverse bias.

Self-assembled materials and devices that process light

NASA Astrophysics Data System (ADS)

Zhu, Peiwang; Kang, Hu; van der Boom, Milko E.; Liu, Zhifu; Xu, Guoyang; Ma, Jing; Zhou, Delai; Ho, Seng-Tiong; Marks, Tobin J.

2004-12-01

Self-assembled superlattices (SASs) are intrinsically acentric and highly cross-linked structures. For organic electro-optics, they offer great advantages such as not requiring electric field poling for creating an acentric, EO-active microstructure and having excellent chemical, thermal, and orientational stabilities. In this paper, a greatly improved two-step all "wet-chemical" self-assembly (SA) approach is reported. Excellent radiation hardness of the SAS films is demonstrated by high-energy proton irradiation experiments. By introducing metal oxide nanolayers during SA, we show that the refractive indices of SAS films can be tuned over a wide range. Through special chromophore design, the optical absorption maxima of SAS films can also be greatly blue-shifted. Prototype waveguiding electro-optic modulators have been fabricated using the SAS films integrated with low-loss polymeric materials functioning as partial guiding and cladding layers. EO parameters such as the half-wave voltage and the effective electro-optic coefficient are reported.

Luminescent characteristics study of Mather-type dense plasma focus and applications to short-wavelength optical pumping. Final technical report, 1 May 1984-30 September 1985

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kim, K.K.

A Mather-type dense plasma focus (MDPF) system was designed, built, and tested specifically to study its luminescent characteristics and to assess its potential as a new light source of high-energy, short-wavelength lasers. The luminescence study of MDPF showed that the conversion efficiency from the electrical input to the optical output energies is at least 50%, up to the time the plasma compression is complete. Using the system, for the first time as an optical pump, laser activities were successfully obtained from a variety of liquid organic dyes. Diagnostic capabilities included an optical multichannel analyzer system complete with a computer control,more » a nitrogen-pumped tunable dye-laser system, a high-speed streak/framing camera, a digital laser energy meter, voltage and current probes, and a computer-based data-acquisition system.« less

Testing methodologies and systems for semiconductor optical amplifiers

NASA Astrophysics Data System (ADS)

Wieckowski, Michael

Semiconductor optical amplifiers (SOA's) are gaining increased prominence in both optical communication systems and high-speed optical processing systems, due primarily to their unique nonlinear characteristics. This in turn, has raised questions regarding their lifetime performance reliability and has generated a demand for effective testing techniques. This is especially critical for industries utilizing SOA's as components for system-in-package products. It is important to note that very little research to date has been conducted in this area, even though production volume and market demand has continued to increase. In this thesis, the reliability of dilute-mode InP semiconductor optical amplifiers is studied experimentally and theoretically. The aging characteristics of the production level devices are demonstrated and the necessary techniques to accurately characterize them are presented. In addition, this work proposes a new methodology for characterizing the optical performance of these devices using measurements in the electrical domain. It is shown that optical performance degradation, specifically with respect to gain, can be directly qualified through measurements of electrical subthreshold differential resistance. This metric exhibits a linear proportionality to the defect concentration in the active region, and as such, can be used for prescreening devices before employing traditional optical testing methods. A complete theoretical analysis is developed in this work to explain this relationship based upon the device's current-voltage curve and its associated leakage and recombination currents. These results are then extended to realize new techniques for testing semiconductor optical amplifiers and other similarly structured devices. These techniques can be employed after fabrication and during packaged operation through the use of a proposed stand-alone testing system, or using a proposed integrated CMOS self-testing circuit. Both methods are capable of ascertaining SOA performance based solely on the subthreshold differential resistance signature, and are a first step toward the inevitable integration of self-testing circuits into complex optoelectronic systems.

High-Speed Semiconductor Vertical-Cavity Surface-Emitting Lasers for Optical Data-Transmission Systems (Review)

NASA Astrophysics Data System (ADS)

Blokhin, S. A.; Maleev, N. A.; Bobrov, M. A.; Kuzmenkov, A. G.; Sakharov, A. V.; Ustinov, V. M.

2018-01-01

The main problems of providing a high-speed operation semiconductor lasers with a vertical microcavity (so-called "vertical-cavity surface-emitting lasers") under amplitude modulation and ways to solve them have been considered. The influence of the internal properties of the radiating active region and the electrical parasitic elements of the equivalent circuit of lasers are discussed. An overview of approaches that lead to an increase of the cutoff parasitic frequency, an increase of the differential gain of the active region, the possibility of the management of mode emission composition and the lifetime of photons in the optical microcavities, and reduction of the influence of thermal effects have been presented. The achieved level of modulation bandwidth of ˜30 GHz is close to the maximum achievable for the classical scheme of the direct-current modulation, which makes it necessary to use a multilevel modulation format to further increase the information capacity of optical channels constructed on the basis of vertical-cavity surface-emitting lasers.

Connexin43 contributes to electrotonic conduction across scar tissue in the intact heart

NASA Astrophysics Data System (ADS)

Mahoney, Vanessa M.; Mezzano, Valeria; Mirams, Gary R.; Maass, Karen; Li, Zhen; Cerrone, Marina; Vasquez, Carolina; Bapat, Aneesh; Delmar, Mario; Morley, Gregory E.

2016-05-01

Studies have demonstrated non-myocytes, including fibroblasts, can electrically couple to myocytes in culture. However, evidence demonstrating current can passively spread across scar tissue in the intact heart remains elusive. We hypothesize electrotonic conduction occurs across non-myocyte gaps in the heart and is partly mediated by Connexin43 (Cx43). We investigated whether non-myocytes in ventricular scar tissue are electrically connected to surrounding myocardial tissue in wild type and fibroblast-specific protein-1 driven conditional Cx43 knock-out mice (Cx43fsp1KO). Electrical coupling between the scar and uninjured myocardium was demonstrated by injecting current into the myocardium and recording depolarization in the scar through optical mapping. Coupling was significantly reduced in Cx43fsp1KO hearts. Voltage signals were recorded using microelectrodes from control scars but no signals were obtained from Cx43fsp1KO hearts. Recordings showed significantly decreased amplitude, depolarized resting membrane potential, increased duration and reduced upstroke velocity compared to surrounding myocytes, suggesting that the non-excitable cells in the scar closely follow myocyte action potentials. These results were further validated by mathematical simulations. Optical mapping demonstrated that current delivered within the scar could induce activation of the surrounding myocardium. These data demonstrate non-myocytes in the scar are electrically coupled to myocytes, and coupling depends on Cx43 expression.

Gate-tunable gigantic changes in lattice parameters and optical properties in VO2

NASA Astrophysics Data System (ADS)

Nakano, Masaki; Okuyama, Daisuke; Shibuya, Keisuke; Ogawa, Naoki; Hatano, Takafumi; Kawasaki, Masashi; Arima, Taka-Hisa; Iwasa, Yoshihiro; Tokura, Yoshinori

2014-03-01

The field-effect transistor provides an electrical switching function of current flowing through a channel surface by external gate voltage (VG). We recently reported that an electric-double-layer transistor (EDLT) based on vanadium dioxide (VO2) enables electrical switching of the metal-insulator phase transition, where the low-temperature insulating state can be completely switched to the metallic state by application of VG. Here we demonstrate that VO2-EDLT enables electrical switching of lattice parameters and optical properties as well as electrical current. We performed in-situ x-ray diffraction and optical transmission spectroscopy measurements, and found that the c-axis length and the infrared transmittance of VO2 can be significantly modulated by more than 1% and 40%, respectively, by application of VG. We emphasize that these distinguished features originate from the electric-field induced bulk phase transition available with VO2-EDLT. This work was supported by the Japan Society for the Promotion of Science (JSPS) through its ``Funding Program for World-Leading Innovative R&D on Science and Technology (FIRST Program).''

Computational optogenetics: A novel continuum framework for the photoelectrochemistry of living systems

NASA Astrophysics Data System (ADS)

Wong, Jonathan; Abilez, Oscar J.; Kuhl, Ellen

2012-06-01

Electrical stimulation is currently the gold standard treatment for heart rhythm disorders. However, electrical pacing is associated with technical limitations and unavoidable potential complications. Recent developments now enable the stimulation of mammalian cells with light using a novel technology known as optogenetics. The optical stimulation of genetically engineered cells has significantly changed our understanding of electrically excitable tissues, paving the way towards controlling heart rhythm disorders by means of photostimulation. Controlling these disorders, in turn, restores coordinated force generation to avoid sudden cardiac death. Here, we report a novel continuum framework for the photoelectrochemistry of living systems that allows us to decipher the mechanisms by which this technology regulates the electrical and mechanical function of the heart. Using a modular multiscale approach, we introduce a non-selective cation channel, channelrhodopsin-2, into a conventional cardiac muscle cell model via an additional photocurrent governed by a light-sensitive gating variable. Upon optical stimulation, this channel opens and allows sodium ions to enter the cell, inducing electrical activation. In side-by-side comparisons with conventional heart muscle cells, we show that photostimulation directly increases the sodium concentration, which indirectly decreases the potassium concentration in the cell, while all other characteristics of the cell remain virtually unchanged. We integrate our model cells into a continuum model for excitable tissue using a nonlinear parabolic second-order partial differential equation, which we discretize in time using finite differences and in space using finite elements. To illustrate the potential of this computational model, we virtually inject our photosensitive cells into different locations of a human heart, and explore its activation sequences upon photostimulation. Our computational optogenetics tool box allows us to virtually probe landscapes of process parameters, and to identify optimal photostimulation sequences with the goal to pace human hearts with light and, ultimately, to restore mechanical function.

Computational Optogenetics: A Novel Continuum Framework for the Photoelectrochemistry of Living Systems.

PubMed

Wong, Jonathan; Abilez, Oscar J; Kuhl, Ellen

2012-06-01

Electrical stimulation is currently the gold standard treatment for heart rhythm disorders. However, electrical pacing is associated with technical limitations and unavoidable potential complications. Recent developments now enable the stimulation of mammalian cells with light using a novel technology known as optogenetics. The optical stimulation of genetically engineered cells has significantly changed our understanding of electrically excitable tissues, paving the way towards controlling heart rhythm disorders by means of photostimulation. Controlling these disorders, in turn, restores coordinated force generation to avoid sudden cardiac death. Here, we report a novel continuum framework for the photoelectrochemistry of living systems that allows us to decipher the mechanisms by which this technology regulates the electrical and mechanical function of the heart. Using a modular multiscale approach, we introduce a non-selective cation channel, channelrhodopsin-2, into a conventional cardiac muscle cell model via an additional photocurrent governed by a light-sensitive gating variable. Upon optical stimulation, this channel opens and allows sodium ions to enter the cell, inducing electrical activation. In side-by-side comparisons with conventional heart muscle cells, we show that photostimulation directly increases the sodium concentration, which indirectly decreases the potassium concentration in the cell, while all other characteristics of the cell remain virtually unchanged. We integrate our model cells into a continuum model for excitable tissue using a nonlinear parabolic second order partial differential equation, which we discretize in time using finite differences and in space using finite elements. To illustrate the potential of this computational model, we virtually inject our photosensitive cells into different locations of a human heart, and explore its activation sequences upon photostimulation. Our computational optogenetics tool box allows us to virtually probe landscapes of process parameters, and to identify optimal photostimulation sequences with the goal to pace human hearts with light and, ultimately, to restore mechanical function.

The Altus Cumulus Electrification Study (ACES): A UAV-Based Science Demonstration

NASA Technical Reports Server (NTRS)

Blakeslee, R. J.; Croskey, C. L.; Desch, M. D.; Farrell, W. M.; Goldberg, R. A.; Houser, J. G.; Kim, H. S.; Mach, D. M.; Mitchell, J. D.; Stoneburner, J. C.

2003-01-01

The Altus Cumulus Electrification Study (ACES) is an unmanned aerial vehicle (UAV)- based project that investigated thunderstorms in the vicinity of the Florida Everglades in August 2002. ACES was conducted to investigate storm electrical activity and its relationship to storm morphology, and to validate satellite-based lightning measurements. In addition, as part of the NASA sponsored UAV-based science demonstration program, this project provided a scientifically useful demonstration of the utility and promise of UAV platforms for Earth science and applications observations. ACES employed the Altus II aircraft, built by General Atomics - Aeronautical Systems, Inc. Key science objectives simultaneously addressed by ACES are to: (1) investigate lightning-storm relationships, (2) study storm electrical budgets, and provide Lightning Imaging Sensor validation. The ACES payload included electrical, magnetic, and optical sensors to remotely characterize the lightning activity and the electrical environment within and around thunderstorms. ACES contributed important electrical and optical measurements not available from other sources. Also, the high altitude vantage point of the UAV observing platform (up to 55,000 feet) provided cloud-top perspective. By taking advantage of its slow flight speed (70 to 100 knots), long endurance, and high altitude flight, the Altus was flown near, and when possible, over (but never into) thunderstorms for long periods of time that allowed investigations to be conducted over entire storm life cycles. An innovative real time weather system was used to identify and vector the aircraft to selected thunderstorms and safely fly around these storms, while, at the same time monitor the weather near our base of operations. In addition, concurrent ground-based observations that included radar (Miami and Key West WSRBD, NASA NPOL), satellite imagery, and lightning (NALDN and Los Alamos EDOT) enable the UAV measurements to be more completely interpreted and evaluated in the context of the thunderstorm structure, evolution, and environment.

Controlling Growth Orientation of Phthalocyanine Films by Electrical Fields

NASA Technical Reports Server (NTRS)

Zhu, S.; Banks, C. E.; Frazier, D. O.; Ila, D.; Muntele, I.; Penn, B. G.; Sharma, A.; Rose, M. Franklin (Technical Monitor)

2001-01-01

Organic Phthalocyanine films have many applications ranging from data storage to various non-linear optical devices whose quality is affected by the growth orientation of Phthalocyanine films. Due to the structural and electrical properties of Phthalocyanine molecules, the film growth orientation depends strongly on the substrate surface states. In this presentation, an electrical field up to 4000 V/cm is introduced during film growth. The Phthalocyanine films are synthesized on quartz substrates using thermal evaporation. An intermediate layer is deposited on some substrates for introducing the electrical field. Scanning electron microscopy, x-ray diffraction, and Fourier transform infrared spectroscopy are used for measuring surface morphology, film structure, and optical properties, respectively. The comparison of Phthalocyanine films grown with and without the electrical field reveals different morphology, film density, and growth orientation, which eventually change optical properties of these films. These results suggest that the growth method in the electrical field can be used to synthesized Phthalocyanine films with a preferred crystal orientation as well as propose an interaction mechanism between the substrate surface and the depositing molecules. The details of growth conditions and of the growth model of how the Phthalocyanine molecules grow in the electrical field will be discussed.

Electrical transport properties of spray deposited transparent conducting ortho-Zn2SnO4 thin films

NASA Astrophysics Data System (ADS)

Ramarajan, R.; Thangaraju, K.; Babu, R. Ramesh; Joseph, D. Paul

2018-04-01

Ortho Zinc Stannate (Zn2SnO4) exhibits excellent electrical and optical properties to serve as alternate transparent electrode in optoelectronic devices. Here we have optimized ortho-Zn2SnO4 thin film by spray pyrolysis method. Deposition was done onto a pre-heated glass substrate at a temperature of 400 °C. The XRD pattern indicated films to be polycrystalline with cubic structure. The surface of films had globular and twisted metal sheet like morphologies. Films were transparent in the visible region with band gap around 3.6 eV. Transport properties were studied by Hall measurements at 300 K. Activation energies were calculated from Arrhenius's plot from temperature dependent electrical measurements and the conduction mechanism is discussed.

Design of electro-active polymer gels as actuator materials

NASA Astrophysics Data System (ADS)

Popovic, Suzana

Smart materials, alternatively called active or adaptive, differ from passive materials in their sensing and activation capability. These materials can sense changes in environment such as: electric field, magnetic field, UV light, pH, temperature. They are capable of responding in numerous ways. Some change their stiffness properties (electro-rheological fluids), other deform (piezos, shape memory alloys, electrostrictive materials) or change optic properties (electrochromic polymers). Polymer gels are one of such materials which can change the shape, volume and even optical properties upon different applied stimuli. Due to their low stiffness property they are capable of having up to 100% of strain in a short time, order of seconds. Their motion resembles the one of biosystems, and they are often seen as possible artificial muscle materials. Despite their delicate nature, appropriate design can make them being used as actuator materials which can form controllable surfaces and mechanical switches. In this study several different groups of polymer gel material were investigated: (a) acrylamide based gels are sensitive to pH and electric field and respond in volume change, (b) polyacrylonitrile (PAN) gel is sensitive to pH and electric field and responds in axial strain and bending, (c) polyvinylalcohol (PVA) gel is sensitive to electric field and responds in axial strain and bending and (d) perfluorinated sulfonic acid membrane, Nafion RTM, is sensitive to electric field and responds in bending. Electro-mechanical and chemo-mechanical behavior of these materials is a function of a variety of phenomena: polymer structure, affinity of polymer to the solvent, charge distribution within material, type of solvent, elasticity of polymer matrix, etc. Modeling of this behavior is a task aimed to identify what is driving mechanism for activation and express it in a quantitative way in terms of deformation of material. In this work behavior of the most promising material as an actuator material, Nafion 117, was simulated. It was suggested that dominant phenomenon causing the material deformation is non-uniform water distribution within a material, that causes it to expand on one side and shrink on the other, macroscopically inducing bending of membrane. Uneven distribution of water is believed to be under the influence of two processes, electroosmosis and self-diffusion of free water.

Closed-loop motor control using high-speed fiber optics

NASA Technical Reports Server (NTRS)

Dawson, Reginald (Inventor); Rodriquiz, Dagobert (Inventor)

1991-01-01

A closed-loop control system for controlling the operation of one or more servo motors or other controllable devices is described. The system employs a fiber optics link immune to electromagnetic interference, for transmission of control signals from a controller or controllers at a remote station to the power electronics located in proximity to the motors or other devices at the local station. At the remote station the electrical control signals are time-multiplexed, converted to a formatted serial bit stream, and converted to light signals for transmission over a single fiber of the fiber optics link. At the local station, the received optical signals are reconstructed as electrical control signals for the controlled motors or other devices. At the local station, an encoder sensor linked to the driven device generates encoded feedback signals which provide information as to a condition of the controlled device. The encoded signals are placed in a formatted serial bit stream, multiplexed, and transmitted as optical signals over a second fiber of the fiber optic link which closes the control loop of the closed-loop motor controller. The encoded optical signals received at the remote station are demultiplexed, reconstructed and coupled to the controller(s) as electrical feedback signals.

An improved segmentation method for defects inspection on steel roller surface

NASA Astrophysics Data System (ADS)

Xu, Jirui; Li, Xuekun; Cao, Yuzhong; Shi, Depeng; Yang, Jun; Jiang, Sheng; Rong, Yiming

2018-05-01

In the field of metal rolling, the quality of the steel roller's surface is significant for the final rolling products, e.g. metal sheets or foils. Besides the dimensional accuracy and surface roughness, the optical uniformity of the roller surface is also required for high quality rolling application. The typical optical defects of rollers after finish grinding include speckles, chatter marks, feed traces, and combination of all above. Unlike surface roughness, the optical defects can hardly be characterized by the topography or scanning electrical microscope measurement. Only the inspection by bared eyes of experienced engineers appears to be the effective manner for surface optical defects examination for large steel rollers. In this paper, an on-site machine vision system is designed to add on to the roller grinding machine to capture the surface image, and then an improved optical defects segmentation algorithm is developed based on the active contour model. Finally, experiments are carried out to verify the efficacy of the improved model.

Optical monitoring of thin film electro-polymerization on surface of ITO-coated lossy-mode resonance sensor

NASA Astrophysics Data System (ADS)

Sobaszek, Michał; Dominik, Magdalena; Burnat, Dariusz; Bogdanowicz, Robert; Stranak, Viteszlav; Sezemsky, Petr; Śmietana, Mateusz

2017-04-01

This work presents an optical fiber sensors based on lossy-mode resonance (LMR) phenomenon supported by indium tin oxide (ITO) thin overlay for investigation of electro-polymerization effect on ITO's surface. The ITO overlays were deposited on core of polymer-clad silica (PCS) fibers using reactive magnetron sputtering (RMS) method. Since ITO is electrically conductive and electrochemically active it can be used as a working electrode in 3-electrode cyclic voltammetry setup. For fixed potential applied to the electrode current flow decrease with time what corresponds to polymer layer formation on the ITO surface. Since LMR phenomenon depends on optical properties in proximity of the ITO surface, polymer layer formation can be monitored optically in real time. The electrodeposition process has been performed with Isatin which is a strong endogenous neurochemical regulator in humans as it is a metabolic derivative of adrenaline. It was found that optical detection of Isatin is possible in the proposed configuration.

Acidosis slows electrical conduction through the atrio-ventricular node

PubMed Central

Nisbet, Ashley M.; Burton, Francis L.; Walker, Nicola L.; Craig, Margaret A.; Cheng, Hongwei; Hancox, Jules C.; Orchard, Clive H.; Smith, Godfrey L.

2014-01-01

Acidosis affects the mechanical and electrical activity of mammalian hearts but comparatively little is known about its effects on the function of the atrio-ventricular node (AVN). In this study, the electrical activity of the epicardial surface of the left ventricle of isolated Langendorff-perfused rabbit hearts was examined using optical methods. Perfusion with hypercapnic Tyrode's solution (20% CO2, pH 6.7) increased the time of earliest activation (Tact) from 100.5 ± 7.9 to 166.1 ± 7.2 ms (n = 8) at a pacing cycle length (PCL) of 300 ms (37°C). Tact increased at shorter PCL, and the hypercapnic solution prolonged Tact further: at 150 ms PCL, Tact was prolonged from 131.0 ± 5.2 to 174.9 ± 16.3 ms. 2:1 AVN block was common at shorter cycle lengths. Atrial and ventricular conduction times were not significantly affected by the hypercapnic solution suggesting that the increased delay originated in the AVN. Isolated right atrial preparations were superfused with Tyrode's solutions at pH 7.4 (control), 6.8 and 6.3. Low pH prolonged the atrial-Hisian (AH) interval, the AVN effective and functional refractory periods and Wenckebach cycle length significantly. Complete AVN block occurred in 6 out of 9 preparations. Optical imaging of conduction at the AV junction revealed increased conduction delay in the region of the AVN, with less marked effects in atrial and ventricular tissue. Thus acidosis can dramatically prolong the AVN delay, and in combination with short cycle lengths, this can cause partial or complete AVN block and is therefore implicated in the development of brady-arrhythmias in conditions of local or systemic acidosis. PMID:25009505

Acidosis slows electrical conduction through the atrio-ventricular node.

PubMed

Nisbet, Ashley M; Burton, Francis L; Walker, Nicola L; Craig, Margaret A; Cheng, Hongwei; Hancox, Jules C; Orchard, Clive H; Smith, Godfrey L

2014-01-01

Acidosis affects the mechanical and electrical activity of mammalian hearts but comparatively little is known about its effects on the function of the atrio-ventricular node (AVN). In this study, the electrical activity of the epicardial surface of the left ventricle of isolated Langendorff-perfused rabbit hearts was examined using optical methods. Perfusion with hypercapnic Tyrode's solution (20% CO2, pH 6.7) increased the time of earliest activation (Tact) from 100.5 ± 7.9 to 166.1 ± 7.2 ms (n = 8) at a pacing cycle length (PCL) of 300 ms (37°C). Tact increased at shorter PCL, and the hypercapnic solution prolonged Tact further: at 150 ms PCL, Tact was prolonged from 131.0 ± 5.2 to 174.9 ± 16.3 ms. 2:1 AVN block was common at shorter cycle lengths. Atrial and ventricular conduction times were not significantly affected by the hypercapnic solution suggesting that the increased delay originated in the AVN. Isolated right atrial preparations were superfused with Tyrode's solutions at pH 7.4 (control), 6.8 and 6.3. Low pH prolonged the atrial-Hisian (AH) interval, the AVN effective and functional refractory periods and Wenckebach cycle length significantly. Complete AVN block occurred in 6 out of 9 preparations. Optical imaging of conduction at the AV junction revealed increased conduction delay in the region of the AVN, with less marked effects in atrial and ventricular tissue. Thus acidosis can dramatically prolong the AVN delay, and in combination with short cycle lengths, this can cause partial or complete AVN block and is therefore implicated in the development of brady-arrhythmias in conditions of local or systemic acidosis.

Graphene doped ZnO films for photoelectrowetting on microchannels

NASA Astrophysics Data System (ADS)

Al-Aribe, Khaled; Knopf, George K.

2017-02-01

Photoelectrowetting on dielectric surfaces can be used to drive droplets of liquid along reconfigurable paths on a microfluidic chip using controlled optical signals. These electrostatically activated surfaces along the desired path eliminate the need for precision molded channels and discrete functional components such as microvalves and micropumps. The photoelectrowetting effect exploits the surface tension of the droplet to maintain its volume during the transportation pathway and the photoelectric properties of the substrate surface are used to induce reversible fluidic flow. The active light-driven substrate is structured from graphene doped zinc-oxide (ZnO-G) films deposited on ITO coated glass. This substrate is coated from the ZnO-G side with Ruthenium-based dye (N719) to maximize its absorbability. The light triggers two forces that enable the droplet to be transported along the substrate. The first arises from the induced hydrophobicity gradient formed across the droplet contact area with the substrate surface. Exposing the ZnO-G film to a broad spectrum white light source alters the surface's electric potential which induces a change in the droplet's contact angle and the associated hydrophobicity. Once the hydrophobicity gradient is generated the droplet will start to move in the direction of the wetting zone. The second force is also created by the optical input when the absorbed light generates a photoelectric potential that produces a piezo-electrical effect on the ZnO-G film. The light triggered piezo-electrical behavior of the ZnO-G film can be used to generate the erasable microchannels that can guide droplet movement through a microfluidic chip. Preliminary experiments are performed to investigate the photoelectric potential of light activated ZnO-G films.

A radioluminescent nuclear battery using volumetric configuration: 63Ni solution/ZnS:Cu,Al/InGaP.

PubMed

Russo, Johnny; Litz, Marc; Ray, William; Smith, Brenda; Moyers, Richard

2017-12-01

Energy dense power sources are critical to the development of compact, remote sensors for terrestrial and space applications. Nuclear batteries using β - -emitting radioisotopes possess energy densities 1000 times greater than chemical batteries. Their power generation is a function of β - flux saturation point relative to the planar (2D) configuration, β - range, and semiconductor converter. An approach to increase power density in a beta-photovoltaic (β-PV) nuclear battery is described. By using volumetric (3D) configuration, the radioisotope, nickel-63 ( 63 Ni) in a chloride solution was integrated in a phosphor film (ZnS:Cu,Al) where the β - energy is converted into optical energy. The optical energy was converted to electrical energy via an indium gallium phosphate (InGaP) photovoltaic (PV) cell, which was optimized for low light illumination and closely matched to radioluminescence (RL) spectrum. With 15mCi of 63 Ni activity, the 3D configuration energy values surpassed 2D configuration results. The highest total power conversion efficiency (η t ) of 3D configuration was 0.289% at 200µm compared 0.0638% for 2D configuration at 50µm. The highest electrical power and η t for the 3D configuration were 3.35 nW e /cm 2 at an activity of 30mCi and 0.289% at an activity of 15mCi, respectively. By using 3D configuration, the interaction space between the radioisotope source and scintillation material increased, allowing for significant electrical energy output, relative to the 2D configuration. These initial results represent a first step to increase nuclear battery power density from microwatts to milliwatts per 1000cm 3 with the implementation of higher energy β - sources. Published by Elsevier Ltd.

Perspective and potential of smart optical materials

NASA Astrophysics Data System (ADS)

Choi, Sang H.; Duzik, Adam J.; Kim, Hyun-Jung; Park, Yeonjoon; Kim, Jaehwan; Ko, Hyun-U.; Kim, Hyun-Chan; Yun, Sungryul; Kyung, Ki-Uk

2017-09-01

The increasing requirements of hyperspectral imaging optics, electro/photo-chromic materials, negative refractive index metamaterial optics, and miniaturized optical components from micro-scale to quantum-scale optics have all contributed to new features and advancements in optics technology. Development of multifunctional capable optics has pushed the boundaries of optics into new fields that require new disciplines and materials to maximize the potential benefits. The purpose of this study is to understand and show the fundamental materials and fabrication technology for field-controlled spectrally active optics (referred to as smart optics) that are essential for future industrial, scientific, military, and space applications, such as membrane optics, filters, windows for sensors and probes, telescopes, spectroscopes, cameras, light valves, light switches, and flat-panel displays. The proposed smart optics are based on the Stark and Zeeman effects in materials tailored with quantum dot arrays and thin films made from readily polarizable materials via ferroelectricity or ferromagnetism. Bound excitonic states of organic crystals are also capable of optical adaptability, tunability, and reconfigurability. To show the benefits of smart optics, this paper reviews spectral characteristics of smart optical materials and device technology. Experiments testing the quantum-confined Stark effect, arising from rare earth element doping effects in semiconductors, and applied electric field effects on spectral and refractive index are discussed. Other bulk and dopant materials were also discovered to have the same aspect of shifts in spectrum and refractive index. Other efforts focus on materials for creating field-controlled spectrally smart active optics on a selected spectral range. Surface plasmon polariton transmission of light through apertures is also discussed, along with potential applications. New breakthroughs in micro scale multiple zone plate optics as a micro convex lens are reviewed, along with the newly discovered pseudo-focal point not predicted with conventional optics modeling. Micron-sized solid state beam scanner chips for laser waveguides are reviewed as well.

Optimization of the optical and electrical properties of electron beam evaporated aluminum-doped zinc oxide films for opto-electronic applications

NASA Astrophysics Data System (ADS)

Ali, H. M.; Abd El-Raheem, M. M.; Megahed, N. M.; Mohamed, H. A.

2006-08-01

Aluminum-doped zinc oxide (AZO) thin films have been deposited by electron beam evaporation technique on glass substrates. The structural, electrical and optical properties of AZO films have been investigated as a function of annealing temperature. It was observed that the optical properties such as transmittance, reflectance, optical band gap and refractive index of AZO films were strongly affected by annealing temperature. The transmittance values of 84% in the visible region and 97% in the NIR region were obtained for AZO film annealed at 475 °C. The room temperature electrical resistivity of 4.6×10-3 Ω cm has been obtained at the same temperature of annealing. It was found that the calculated refractive index has been affected by the packing density of the thin films, whereas, the high annealing temperature gave rise to improve the homogeneity of the films. The single-oscillator model was used to analyze the optical parameters such as the oscillator and dispersion energies.

Effect of annealing over optoelectronic properties of graphene based transparent electrodes

NASA Astrophysics Data System (ADS)

Yadav, Shriniwas; Kaur, Inderpreet

2016-04-01

Graphene, an atom-thick two dimensional graphitic material have led various fundamental breakthroughs in the field of science and technology. Due to their exceptional optical, physical and electrical properties, graphene based transparent electrodes have shown several applications in organic light emitting diodes, solar cells and thin film transistors. Here, we are presenting effect of annealing over optoelectronic properties of graphene based transparent electrodes. Graphene based transparent electrodes have been prepared by wet chemical approach over glass substrates. After fabrication, these electrodes tested for optical transmittance in visible region. Sheet resistance was measured using four probe method. Effect of thermal annealing at 200 °C was studied over optical and electrical performance of these electrodes. Optoelectronic performance was judged from ratio of direct current conductivity to optical conductivity (σdc/σopt) as a figure of merit for transparent conductors. The fabricated electrodes display good optical and electrical properties. Such electrodes can be alternatives for doped metal oxide based transparent electrodes.

Theoretical analysis of optical poling and frequency doubling effect based on classical model

NASA Astrophysics Data System (ADS)

Feng, Xi; Li, Fuquan; Lin, Aoxiang; Wang, Fang; Chai, Xiangxu; Wang, Zhengping; Zhu, Qihua; Sun, Xun; Zhang, Sen; Sun, Xibo

2018-03-01

Optical poling and frequency doubling effect is one of the effective manners to induce second order nonlinearity and realize frequency doubling in glass materials. The classical model believes that an internal electric field is built in glass when it's exposed by fundamental and frequency-doubled light at the same time, and second order nonlinearity appears as a result of the electric field and the orientation of poles. The process of frequency doubling in glass is quasi phase matched. In this letter, the physical process of poling and doubling process in optical poling and frequency doubling effect is deeply discussed in detail. The magnitude and direction of internal electric field, second order nonlinear coefficient and its components, strength and direction of frequency doubled output signal, quasi phase matched coupled wave equations are given in analytic expression. Model of optical poling and frequency doubling effect which can be quantitatively analyzed are constructed in theory, which set a foundation for intensive study of optical poling and frequency doubling effect.

Plasmonic hole arrays for combined photon and electron management

DOE PAGES

Liapis, Andreas C.; Sfeir, Matthew Y.; Black, Charles T.

2016-11-14

Material architectures that balance optical transparency and electrical conductivity are highly sought after for thin-film device applications. However, these are competing properties, since the electronic structure that gives rise to conductivity typically also leads to optical opacity. Nanostructured metal films that exhibit extraordinary optical transmission, while at the same time being electrically continuous, offer considerable flexibility in the design of their transparency and resistivity. In this paper, we present design guidelines for metal films perforated with arrays of nanometer-scale holes, discussing the consequences of the choice of nanostructure dimensions, of the type of metal, and of the underlying substrate onmore » their electrical, optical, and interfacial properties. We experimentally demonstrate that such films can be designed to have broad-band optical transparency while being an order of magnitude more conductive than indium tin oxide. Finally, prototypical photovoltaic devices constructed with perforated metal contacts convert ~18% of the incident photons, compared to <1% for identical devices having contacts without the hole array.« less

Pattern manipulation via on-chip phase modulation between orbital angular momentum beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Huanlu; School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LP; Strain, Michael J.

2015-08-03

An integrated approach to thermal modulation of relative phase between two optical vortices with opposite chirality has been demonstrated on a silicon-on-insulator substrate. The device consists of a silicon-integrated optical vortex emitter and a phase controlled 3 dB coupler. The relative phase between two optical vortices can be actively modulated on chip by applying a voltage on the integrated heater. The phase shift is shown to be linearly proportional to applied electrical power, and the rotation angle of the interference pattern is observed to be inversely proportional to topological charge. This scheme can be used in lab-on-chip, communications and sensing applications.more » It can be intentionally implemented with other modulation elements to achieve more complicated applications.« less

High-speed electro-optic switch with -80 dB crosstalk

NASA Technical Reports Server (NTRS)

Pan, J. J.; Su, W. H.; Xu, J. Y.; Grove, C. H.

1992-01-01

Special device modeling, design and layout, and precision processing controls were employed to fabricate new balanced-bridge 2x2 and 4x4 switches on X-cut, Y-propagation LiNbO3 substrate using Ti indiffused optical waveguides. The best of these devices achieved extinction ratio and crosstalk isolation of better than 93 dB electrically (46.5 dB optically). The new switches demonstrate good reproducibility with electrical crosstalk less than -80 dB.

Analysis of tuning methods in semiconductor frequency-selective surfaces

NASA Astrophysics Data System (ADS)

Shemelya, Corey; Palm, Dominic; Fip, Tassilo; Rahm, Marco

2017-02-01

Advanced technology, such as sensing and communication equipment, has recently begun to combine optically sensitive nano-scale structures with customizable semiconductor material systems. Included within this broad field of study is the aptly named frequency-selective surface; which is unique in that it can be artificially designed to produce a specific electromagnetic or optical response. With the inherent utility of a frequency-selective surface, there has been an increased interest in the area of dynamic frequency-selective surfaces, which can be altered through optical or electrical tuning. This area has had exciting break throughs as tuning methods have evolved; however, these methods are typically energy intensive (optical tuning) or have met with limited success (electrical tuning). As such, this work investigates multiple structures and processes which implement semiconductor electrical biasing and/or optical tuning. Within this study are surfaces ranging from transmission meta-structures to metamaterial surface-waves and the associated coupling schemes. This work shows the utility of each design, while highlighting potential methods for optimizing dynamic meta-surfaces. As an added constraint, the structures were also designed to operate in unison with a state-of-the-art Ti:Sapphire Spitfire Ace and Spitfire Ace PA dual system (12 Watt) with pulse front matching THz generation and an EOS detection system. Additionally, the Ti:Sapphire laser system would provide the means for optical tunablity, while electrical tuning can be obtained through external power supplies.

Optical pendulum generator based on photomechanical liquid-crystalline actuators.

PubMed

Tang, Rong; Liu, Ziyi; Xu, Dandan; Liu, Jian; Yu, Li; Yu, Haifeng

2015-04-29

For converting light energy into electricity, an optical pendulum generator was designed by combining photomechanical movement of liquid-crystalline actuator (LCA) with Faraday's law of electromagnetic induction. Bilayer cantilever actuators were first fabricated with LDPE and LCA. Their photomechanical movement drove the attached copper coils to cut magnetic line of force generating electricity. The output electricity was proportional to the changing rate of the magnetic flux, which was greatly influenced by light intensity, film thickness, and sample size. Continuous electrical output was also achieved. This simple strategy may expand applications of photoactive materials in the capture and storage of light energy.

Optical and Electric Multifunctional CMOS Image Sensors for On-Chip Biosensing Applications

PubMed Central

Tokuda, Takashi; Noda, Toshihiko; Sasagawa, Kiyotaka; Ohta, Jun

2010-01-01

In this review, the concept, design, performance, and a functional demonstration of multifunctional complementary metal-oxide-semiconductor (CMOS) image sensors dedicated to on-chip biosensing applications are described. We developed a sensor architecture that allows flexible configuration of a sensing pixel array consisting of optical and electric sensing pixels, and designed multifunctional CMOS image sensors that can sense light intensity and electric potential or apply a voltage to an on-chip measurement target. We describe the sensors’ architecture on the basis of the type of electric measurement or imaging functionalities. PMID:28879978

Frontiers of Glass Science. Scientific Research Conference Held at Los Angeles, California on 16-18 July 1980.

DTIC Science & Technology

1981-01-01

AFB, DC 20332 102 NIFE r A- 14. MONI1TORING AGEN1CY N AME & AD1DRESS(II dllforenl I,,,,, Co111,11rng 0111c) IS SE7UPITY CL~ASS. t, ’?.,r Unclaiis s if...Optical and Electrical Properties , Amorphous Semiconductors and Electrical Proper-ties, Lens Common Class5es, ind ni nd Fur’acos and ’!-em-:ci’ Y...Scholze H. Kawazoe THURSDAY, 17 JULY SESSION II. OPTICAL & ELECTRICAL PROPERTIES S. Ovshinsky J. Isard SESSION III. AMORPHOUS SEMICONDUCTORS & ELECTRICAL

Optical and electrical properties of GaN-based light emitting diodes grown on micro- and nano-scale patterned Si substrate

NASA Astrophysics Data System (ADS)

Chiu, Ching-Hsueh; Lin, Chien-Chung; Deng, Dongmei; Kuo, Hao-Chung; Lau, Kei-May

2011-10-01

We investigate the optical and electrical characteristics of the GaN-based light emitting diodes (LEDs) grown on Micro and Nano-scale Patterned silicon substrate (MPLEDs and NPLEDs). The transmission electron microscopy (TEM) images reveal the suppression of threading dislocation density in InGaN/GaN structure on nano-pattern substrate due to nanoscale epitaxial lateral overgrowth (NELOG). The plan-view and cross-section cathodoluminescence (CL) mappings show less defective and more homogeneous active quantum well region growth on nano-porous substrates. From temperature dependent photoluminescence (PL) and low temperature time-resolved photoluminescence (TRPL) measurement, NPLEDs has better carrier confinement and higher radiative recombination rate than MPLEDs. In terms of device performance, NPLEDs exhibits smaller electroluminescence (EL) peak wavelength blue shift, lower reverse leakage current and decreases efficiency droop compared with the MPLEDs. These results suggest the feasibility of using NPSi for the growth of high quality and power LEDs on Si substrates.

Prefire identification for pulse-power systems

DOEpatents

Longmire, J.L.; Thuot, M.E.; Warren, D.S.

1982-08-23

Prefires in a high-power, high-frequency, multi-stage pulse generator are detected by a system having an EMI shielded pulse timing transmitter associated with and tailored to each stage of the pulse generator. Each pulse timing transmitter upon detection of a pulse triggers a laser diode to send an optical signal through a high frequency fiber optic cable to a pulse timing receiver which converts the optical signal to an electrical pulse. The electrical pulses from all pulse timing receivers are fed through an OR circuit to start a time interval measuring device and each electrical pulse is used to stop an individual channel in the measuring device thereby recording the firing sequence of the multi-stage pulse generator.

Prefire identification for pulse power systems

DOEpatents

Longmire, Jerry L.; Thuot, Michael E.; Warren, David S.

1985-01-01

Prefires in a high-power, high-frequency, multi-stage pulse generator are detected by a system having an EMI shielded pulse timing transmitter associated with and tailored to each stage of the pulse generator. Each pulse timing transmitter upon detection of a pulse triggers a laser diode to send an optical signal through a high frequency fiber optic cable to a pulse timing receiver which converts the optical signal to an electrical pulse. The electrical pulses from all pulse timing receivers are fed through an OR circuit to start a time interval measuring device and each electrical pulse is used to stop an individual channel in the measuring device thereby recording the firing sequence of the multi-stage pulse generator.

Electrically tunable infrared metamaterial devices

DOEpatents

Brener, Igal; Jun, Young Chul

2015-07-21

A wavelength-tunable, depletion-type infrared metamaterial optical device is provided. The device includes a thin, highly doped epilayer whose electrical permittivity can become negative at some infrared wavelengths. This highly-doped buried layer optically couples with a metamaterial layer. Changes in the transmission spectrum of the device can be induced via the electrical control of this optical coupling. An embodiment includes a contact layer of semiconductor material that is sufficiently doped for operation as a contact layer and that is effectively transparent to an operating range of infrared wavelengths, a thin, highly doped buried layer of epitaxially grown semiconductor material that overlies the contact layer, and a metallized layer overlying the buried layer and patterned as a resonant metamaterial.

Sol-Gel Material-Enabled Electro-Optic Polymer Modulators

PubMed Central

Himmelhuber, Roland; Norwood, Robert A.; Enami, Yasufumi; Peyghambarian, Nasser

2015-01-01

Sol-gels are an important material class, as they provide easy modification of material properties, good processability and are easy to synthesize. In general, an electro-optic (EO) modulator transforms an electrical signal into an optical signal. The incoming electrical signal is most commonly information encoded in a voltage change. This voltage change is then transformed into either a phase change or an intensity change in the light signal. The less voltage needed to drive the modulator and the lower the optical loss, the higher the link gain and, therefore, the better the performance of the modulator. In this review, we will show how sol-gels can be used to enhance the performance of electro-optic modulators by allowing for designs with low optical loss, increased poling efficiency and manipulation of the electric field used for driving the modulator. The optical loss is influenced by the propagation loss in the device, as well as the losses occurring during fiber coupling in and out of the device. In both cases, the use of sol-gel materials can be beneficial due to the wide range of available refractive indices and low optical attenuation. The influence of material properties and synthesis conditions on the device performance will be discussed. PMID:26225971

Electro-optical effects in porous PET films filled with liquid crystal: new possibilities for fiber optics and THZ applications.

PubMed

Chopik, A; Pasechnik, S; Semerenko, D; Shmeliova, D; Dubtsov, A; Srivastava, A K; Chigrinov, V

2014-03-15

The results of investigation of electro-optical properties of porous polyethylene terephthalate films filled with a nematic liquid crystal (5 CB) are presented. It is established that the optical response of the samples on the applied voltage drastically depends on the frequency range. At low frequencies of applied electrical field (ffc) electric field induces an overall change in the light intensity, which is typical for an electro-optical response of a liquid crystal (LC) layer in a conventional "sandwich"-like cell. The dependences of critical frequency fc, threshold voltages, and characteristic times on a pore diameter d were established. The peculiarities of electro-optical effects can be explained in the framework of the approach which connects the variations of light intensity with the corresponding changes of the effective refractive index n(eff) of a composite LC media. The unusual behavior of the electro-optical response at low frequencies is assigned to the orienting action of the specific shear flow typical for electrokinetic phenomena in polar liquids.

Solitons induced by alternating electric fields in surface-stabilized ferroelectric liquid crystals

NASA Astrophysics Data System (ADS)

Jeżewski, W.; Kuczyński, W.; Hoffmann, J.

2011-04-01

Propagation of solitary waves activated in thin ferroelectric liquid crystal cells under external, sinusoidally alternating electric fields is investigated using the electro-optic technique. It is shown that solitons give contributions only to the loss component of the response spectrum, within rather narrow ranges of frequencies and in sufficiently strong fields. The limit frequency, at which the amplitude of the velocity of the solitary waves is greatest, is found to be related to material constants of liquid crystals. Measuring this threshold frequency provides the capability to determine the elastic constant of surface stabilized liquid crystalline materials in the bookshelf or chevron layer geometries.

Infrared neural stimulation (INS) inhibits electrically evoked neural responses in the deaf white cat

NASA Astrophysics Data System (ADS)

Richter, Claus-Peter; Rajguru, Suhrud M.; Robinson, Alan; Young, Hunter K.

2014-03-01

Infrared neural stimulation (INS) has been used in the past to evoke neural activity from hearing and partially deaf animals. All the responses were excitatory. In Aplysia californica, Duke and coworkers demonstrated that INS also inhibits neural responses [1], which similar observations were made in the vestibular system [2, 3]. In deaf white cats that have cochleae with largely reduced spiral ganglion neuron counts and a significant degeneration of the organ of Corti, no cochlear compound action potentials could be observed during INS alone. However, the combined electrical and optical stimulation demonstrated inhibitory responses during irradiation with infrared light.

Aligned Single Wall Carbon Nanotube Polymer Composites Using an Electric Field

NASA Technical Reports Server (NTRS)

Park, Cheol; Wiklinson, John; Banda, Sumanth; Ounaies, Zoubeida; Wise, Kristopher E.; Sauti, Godfrey; Lillehei, Peter T.; Harrison, Joycelyn S.

2005-01-01

While high shear alignment has been shown to improve the mechanical properties of single wall carbon nanotubes (SWNT)-polymer composites, it is difficult to control and often results in degradation of the electrical and dielectric properties of the composite. Here, we report a novel method to actively align SWNTs in a polymer matrix, which allows for control over the degree of alignment of SWNTs without the side effects of shear alignment. In this process, SWNTs are aligned via field-induced dipolar interactions among the nanotubes under an AC electric field in a liquid matrix followed by immobilization by photopolymerization while maintaining the electric field. Alignment of SWNTs was controlled as a function of magnitude, frequency, and application time of the applied electric field. The degree of SWNT alignment was assessed using optical microscopy and polarized Raman spectroscopy and the morphology of the aligned nanocomposites was investigated by high resolution scanning electron microscopy. The structure of the field induced aligned SWNTs is intrinsically different from that of shear aligned SWNTs. In the present work, SWNTs are not only aligned along the field, but also migrate laterally to form thick, aligned SWNT percolative columns between the electrodes. The actively aligned SWNTs amplify the electrical and dielectric properties in addition to improving the mechanical properties of the composite. All of these properties of the aligned nanocomposites exhibited anisotropic characteristics, which were controllable by tuning the applied field conditions.

Nanomechanical Optical Fiber with Embedded Electrodes Actuated by Joule Heating.

PubMed

Lian, Zhenggang; Segura, Martha; Podoliak, Nina; Feng, Xian; White, Nicholas; Horak, Peter

2014-07-31

Nanomechanical optical fibers with metal electrodes embedded in the jacket were fabricated by a multi-material co-draw technique. At the center of the fibers, two glass cores suspended by thin membranes and surrounded by air form a directional coupler that is highly temperature-dependent. We demonstrate optical switching between the two fiber cores by Joule heating of the electrodes with as little as 0.4 W electrical power, thereby demonstrating an electrically actuated all-fiber microelectromechanical system (MEMS). Simulations show that the main mechanism for optical switching is the transverse thermal expansion of the fiber structure.

Demodulation of micro fiber-optic Fabry-Perot interferometer using subcarrier and dual-wavelength method

NASA Astrophysics Data System (ADS)

Lu, En; Ran, Zengling; Peng, Fei; Liu, Zhiwei; Xu, Fuguo

2012-03-01

Subcarrier technology and dual-wavelength demodulation method are combined for tracking the cavity length variation of a micro fiber-optic Fabry-Perot (F-P). Compared with conventional dual-wavelength demodulation method, two operation wavelengths for demodulation are modulated with two different carrier frequencies, respectively, and then injected into optical link connected with the F-P cavity. Light power reflected for the two wavelengths is obtained by interrogating the powers of Fast Fourier Transform (FFT) spectrum at their carrier frequencies. Because the light at the two wavelengths experiences the same optical and electrical routes, measurement deviation resulting from the drift of optical and electrical links can be entirely eliminated.

Demodulation of micro fiber-optic Fabry-Perot interferometer using subcarrier and dual-wavelength method

NASA Astrophysics Data System (ADS)

Ran, Zengling; Rao, Yunjiang; Liu, Zhiwei; Xu, Fuguo

2011-05-01

Subcarrier technology and dual-wavelength demodulation method are combined for tracking the cavity length variation of a micro fiber-optic fabry-periot (F-P). Compared with conventional dual-wavelength demodulation method, two operation wavelengths for demodulation are modulated with two different carrier frequencies, respectively, and then injected into optical link connected with the F-P cavity. Light power reflected for the two wavelengths is obtained by interrogating the powers of Fast Fourier Transform (FFT) spectrum at their carrier frequencies. Because the light at the two wavelengths experiences the same optical and electrical routes, measurement deviation resulting from the drift of optical and electrical links can be entirely eliminated.

Droplet actuator analyzer with cartridge

NASA Technical Reports Server (NTRS)

Sturmer, Ryan A. (Inventor); Paik, Philip Y. (Inventor); Srinivasan, Vijay (Inventor); Brafford, Keith R. (Inventor); West, Richard M. (Inventor); Smith, Gregory F. (Inventor); Pollack, Michael G. (Inventor); Pamula, Vamsee K. (Inventor)

2011-01-01

A droplet actuator with cartridge is provided. According to one embodiment, a sample analyzer is provided and includes an analyzer unit comprising electronic or optical receiving means, a cartridge comprising self-contained droplet handling capabilities, and a wherein the cartridge is coupled to the analyzer unit by a means which aligns electronic and/or optical outputs from the cartridge with electronic or optical receiving means on the analyzer unit. According to another embodiment, a sample analyzer is provided and includes a sample analyzer comprising a cartridge coupled thereto and a means of electrical interface and/or optical interface between the cartridge and the analyzer, whereby electrical signals and/or optical signals may be transmitted from the cartridge to the analyzer.