Optical Measurement and Visualization in High-Pressure, High-Temperature, Aviation Gas Turbine Combustors

NASA Technical Reports Server (NTRS)

Hicks, Yolanda R.; Anderson, Robert C.; Locke, Randy J.

2000-01-01

Planar laser-induced fluorescence (PLIF), planar Mie scattering (PMie), and linear (1-D) spontaneous Raman scattering are applied to flame tube and sector combustors that burn Jet-A fuel at a range of inlet temperatures and pressures that simulate conditions expected in future high-performance civilian gas turbine engines. Chemiluminescence arising from C2 in the flame was also imaged. Flame spectral emissions measurements were obtained using a scanning spectrometer. Several different advanced concept fuel injectors were examined. First-ever PLIF and chemiluminescence data are presented from the 60-atm Gas turbine combustor facility.

Planar super-oscillatory lens for sub-diffraction optical needles at violet wavelengths

PubMed Central

Yuan, Guanghui; Rogers, Edward T. F.; Roy, Tapashree; Adamo, Giorgio; Shen, Zexiang; Zheludev, Nikolay I.

2014-01-01

Planar optical lenses are fundamental elements of miniaturized photonic devices. However, conventional planar optical lenses are constrained by the diffraction limit in the optical far-field due to the band-limited wavevectors supported by free-space and loss of high-spatial-frequency evanescent components. As inspired by Einstein's radiation ‘needle stick', electromagnetic energy can be delivered into an arbitrarily small solid angle. Such sub-diffraction optical needles have been numerically investigated using diffractive optical elements (DOEs) together with specially polarized optical beams, but experimental demonstration is extremely difficult due to the bulky size of DOEs and the required alignment precision. Planar super-oscillatory lenses (SOLs) were proposed to overcome these constraints and demonstrated that sub-diffraction focal spots can actually be formed without any evanescent waves, making far-field, label-free super-resolution imaging possible. Here we extend the super-oscillation concept into the vectorial-field regime to work with circularly polarized light, and experimentally demonstrate, for the first time, a circularly polarized optical needle with sub-diffraction transverse spot size (0.45λ) and axial long depth of focus (DOF) of 15λ using a planar SOL at a violet wavelength of 405 nm. This sub-diffraction circularly polarized optical needle has potential applications in circular dichroism spectroscopy, super-resolution imaging, high-density optical storage, heat-assisted magnetic recording, nano-manufacturing and nano-metrology. PMID:25208611

Optically reconfigurable patterning for control of the propagation characteristics of a planar waveguide

NASA Astrophysics Data System (ADS)

Wang, Y.; Klittnick, A.; Clark, N. A.; Keller, P.

2008-10-01

We demonstrate an easily fabricated all-optical and freely reconfigurable method of controlling the propagating characteristics of the optic path within a planar waveguide with low insertion losses by employing the optical patterning of the refractive index of an erasable and rewriteable photosensitive liquid crystal polymer cladding layer.

Mode structure of planar optical antennas on dielectric substrates

DOE PAGES

Word, Robert C.; Konenkamp, Rolf

2016-08-08

Here, we report a numerical study, supported by photoemission electron microscopy (PEEM), of sub-micron planar optical antennas on transparent substrate. We find these antennas generate intricate near-field spatial field distributions with odd and even numbers of nodes. We show that the field distributions are primarily superpositions of planar surface plasmon polariton modes confined to the metal/substrate interface. The mode structure provides opportunities for coherent switching and optical control in sub-micron volumes.

Planar integrated optics, a new solution in optical instrumentation

NASA Astrophysics Data System (ADS)

Haguenauer, P.

2017-11-01

Planar integrated optics present an attractive solution for future instrumentation, both in ground and space based applications. The technologies used in the manufacturing of such components, supported by research laboratories as well as industries, are mature enough to provide complex devices.

Fast Erase Method and Apparatus For Digital Media

NASA Technical Reports Server (NTRS)

Oakely, Ernest C. (Inventor)

2006-01-01

A non-contact fast erase method for erasing information stored on a magnetic or optical media. The magnetic media element includes a magnetic surface affixed to a toroidal conductor and stores information in a magnetic polarization pattern. The fast erase method includes applying an alternating current to a planar inductive element positioned near the toroidal conductor, inducing an alternating current in the toroidal conductor, and heating the magnetic surface to a temperature that exceeds the Curie-point so that information stored on the magnetic media element is permanently erased. The optical disc element stores information in a plurality of locations being defined by pits and lands in a toroidal conductive layer. The fast erase method includes similarly inducing a plurality of currents in the optical media element conductive layer and melting a predetermined portion of the conductive layer so that the information stored on the optical medium is destroyed.

Research on laser-induced damage resistance of fused silica optics by the fluid jet polishing method.

PubMed

Lv, Liang; Ma, Ping; Huang, Jinyong; He, Xiang; Cai, Chao; Zhu, Heng

2016-03-20

Laser-induced damage threshold (LIDT) is one important evaluation index for optical glasses applied in large laser instruments which are exposed to high light irradiation flux. As a new kind of precise polishing technology, fluid jet polishing (FJP) has been widely used in generating planar, spherical, and aspherical optics with high-accuracy surfaces. Laser damage resistances of fused silica optics by the FJP process are studied in this paper. Fused silica samples with various FJP parameters are prepared, and laser damage experiments are performed with 351 nm wavelength and a 5.5 ns pulse width laser. Experimental results demonstrate that the LIDT of the samples treated with FJP processes did not increase, compared to their original state. The surface quality of the samples is one factor for the decrease of LIDT. For ceria solution polished samples, the cerium element remaining is another factor of the lower LIDT.

Single Fiber Star Couplers. [optical waveguides for spacecraft communication

NASA Technical Reports Server (NTRS)

Asawa, C. K.

1979-01-01

An ion exchange process was developed and used in the fabrication of state-of-the-art planar star couplers for distribution of optical radiation between optical fibers. An 8 x 8 planar transmission star coupler was packaged for evaluation purposes with sixteen fiber connectors and sixteen pigtails. Likewise a transmission star coupler and an eight-port reflection star coupler with eight-fiber ribbons rigidly attached to these couplers, and a planar coupler with silicon guides and a parallel channel guide with pigtails were also fabricated. Optical measurements of the transmission star couplers are included with a description of the manufacturing process.

Observation of extraordinary optical activity in planar chiral photonic crystals.

PubMed

Konishi, Kuniaki; Bai, Benfeng; Meng, Xiangfeng; Karvinen, Petri; Turunen, Jari; Svirko, Yuri P; Kuwata-Gonokami, Makoto

2008-05-12

Control of light polarization is a key technology in modern photonics including application to optical manipulation of quantum information. The requisite is to obtain large rotation in isotropic media with small loss. We report on extraordinary optical activity in a planar dielectric on-waveguide photonic crystal structure, which has no in-plane birefringence and shows polarization rotation of more than 25 degrees for transmitted light. We demonstrate that in the planar chiral photonic crystal, the coupling of the normally incident light wave with low-loss waveguide and Fabry-Pérot resonance modes results in a dramatic enhancement of the optical activity.

Optical microspectrometer

DOEpatents

Sweatt, William C.; Christenson, Todd R.

2004-05-25

An optical microspectrometer comprises a grism to disperse the spectra in a line object. A single optical microspectrometer can be used to sequentially scan a planar object, such as a dye-tagged microchip. Because the optical microspectrometer is very compact, multiple optical microspectrometers can be arrayed to provide simultaneous readout across the width of the planar object The optical microspectrometer can be fabricated with lithographic process, such as deep X-ray lithography (DXRL), with as few as two perpendicular exposures.

Molecular filter-based diagnostics in high speed flows

NASA Technical Reports Server (NTRS)

Elliott, Gregory S.; Samimy, MO; Arnette, Stephen A.

1993-01-01

The use of iodine molecular filters in nonintrusive planar velocimetry methods is examined. Detailed absorption profiles are obtained to highlight the effects that determine the profile shape. It is shown that pressure broadening induced by the presence of a nonabsorbing vapor can be utilized to significantly change the slopes bounding the absorbing region while remaining in the optically-thick regime.

All Fiber-Coupled OH Planar Laser-Induced-Fluorescence (OH-PLIF)-Based Two-Dimensional Thermometry.

PubMed

Hsu, Paul S; Jiang, Naibo; Patnaik, Anil K; Katta, Vish; Roy, Sukesh; Gord, James R

2018-04-01

Two-color, planar laser-induced fluorescence (PLIF)-based two-dimensional (2D) thermometry techniques for reacting flows, which are typically developed in the laboratory conditions, face a stiff challenge in their practical implementation in harsh environments such as combustion rigs. In addition to limited optical access, the critical experimental conditions (i.e., uncontrolled humidity, vibration, and large thermal gradients) often restrict sensitive laser system operation and cause difficulties maintaining beam-overlap. Thus, an all fiber-coupled, two-color OH-PLIF system has been developed, employing two long optical fibers allowing isolation of the laser and signal-collection systems. Two OH-excitation laser beams (∼283 nm and ∼286 nm) are delivered through a common 6 m long, 400 µm core, deep ultraviolet (UV)-enhanced multimode fiber. The fluorescence signal (∼310 nm) is collected by a 3 m long, UV-grade imaging fiber. Proof-of-principle temperature measurements are demonstrated in atmospheric pressure, near adiabatic, CH 4 /O 2 /N 2 jet flames. The effects of the excitation pulse interval on fiber transmission are investigated. The proof-of-principle measurements show significant promise for thermometry in harsh environments such as gas turbine engine tests.

Fundamental and practical limits of planar tracking solar concentrators.

PubMed

Grede, Alex J; Price, Jared S; Giebink, Noel C

2016-12-26

Planar microtracking provides an alternate paradigm for solar concentration that offers the possibility of realizing high-efficiency embedded concentrating photovoltaic systems in the form factor of standard photovoltaic panels. Here, we investigate the thermodynamic limit of planar tracking optical concentrators and establish that they can, in principal, achieve the sine limit of their orientationally-tracked counterparts provided that the receiver translates a minimum distance set by the field of view half-angle. We develop a phase space methodology to optimize practical planar tracking concentrators and apply it to the design of a two surface, catadioptric system that operates with > 90% optical efficiency over a 140° field of view at geometric gains exceeding 1000×. These results provide a reference point for subsequent developments in the field and indicate that planar microtracking can achieve the high optical concentration ratio required in commercial concentrating photovoltaic systems.

Application of holographic elements in displays and planar illuminators

NASA Astrophysics Data System (ADS)

Putilin, Andrew; Gustomiasov, Igor

2007-05-01

Holographic Optical Elements (HOE's) on planar waveguides can be used to design the planar optics for backlit units, color selectors or filters, lenses for virtual reality displays. The several schemes for HOE recording are proposed to obtain planar stereo backlit unit and private eye displays light source. It is shown in the paper that the specific light transformation grating permits to construct efficient backlit units for display holograms and LCD. Several schemes of reflection/transmission backlit units and scattering films based on holographic optical elements are also proposed. The performance of the waveguide HOE can be optimized using the parameters of recording scheme and etching parameters. The schemes of HOE application are discussed and some experimental results are shown.

Optical fiber head for providing lateral viewing

DOEpatents

Everett, Matthew J.; Colston, Billy W.; James, Dale L.; Brown, Steve; Da Silva, Luiz

2002-01-01

The head of an optical fiber comprising the sensing probe of an optical heterodyne sensing device includes a planar surface that intersects the perpendicular to axial centerline of the fiber at a polishing angle .theta.. The planar surface is coated with a reflective material so that light traveling axially through the fiber is reflected transverse to the fiber's axial centerline, and is emitted laterally through the side of the fiber. Alternatively, the planar surface can be left uncoated. The polishing angle .theta. must be no greater than 39.degree. or must be at least 51.degree.. The emitted light is reflected from adjacent biological tissue, collected by the head, and then processed to provide real-time images of the tissue. The method for forming the planar surface includes shearing the end of the optical fiber and applying the reflective material before removing the buffer that circumscribes the cladding and the core.

Thermal emergence of laser-induced spin dynamics for a Ni4 cluster

NASA Astrophysics Data System (ADS)

Sold, S.; Lefkidis, G.; Kamble, B.; Berakdar, J.; Hübner, W.

2018-05-01

We investigate the thermodynamic behavior of laser-induced spin dynamics of a perfect and a distorted Ni4 square in combination with an external thermal bath, by using the Lindblad-superoperator formalism. The energies of the planar molecules are determined with highly correlated ab initio quantum-chemistry calculations. When the distorted structure couples to the thermal bath a unique spin dynamics, i.e., a spin flip, emerges, due to the interplay of optically and thermally induced electronic transitions. The charge and spin relaxation times in dependence on the coupling strength and the bath temperature are determined and compared.

Design and investigation of properties of nanocrystalline diamond optical planar waveguides.

PubMed

Prajzler, Vaclav; Varga, Marian; Nekvindova, Pavla; Remes, Zdenek; Kromka, Alexander

2013-04-08

Diamond thin films have remarkable properties comparable with natural diamond. Because of these properties it is a very promising material for many various applications (sensors, heat sink, optical mirrors, chemical and radiation wear, cold cathodes, tissue engineering, etc.) In this paper we report about design, deposition and measurement of properties of optical planar waveguides fabricated from nanocrystalline diamond thin films. The nanocrystalline diamond planar waveguide was deposited by microwave plasma enhanced chemical vapor deposition and the structure of the deposited film was studied by scanning electron microscopy and Raman spectroscopy. The design of the presented planar waveguides was realized on the bases of modified dispersion equation and was schemed for 632.8 nm, 964 nm, 1 310 nm and 1 550 nm wavelengths. Waveguiding properties were examined by prism coupling technique and it was found that the diamond based planar optical element guided one fundamental mode for all measured wavelengths. Values of the refractive indices of our NCD thin film measured at various wavelengths were almost the same as those of natural diamond.

Development of integrated optical tracking sensor by planar optics

NASA Astrophysics Data System (ADS)

Kawano, Hiroyuki; Sasagawa, Tomohiro; Nishimae, Junichi; Sato, Yukio

1999-03-01

A compact and light weight optical tracking sensor for a large capacity flexible disk drive is demonstrated. The size of the optical element is no larger than 5.4 mm in length X 3.6 mm in width X 1.2 mm in height and the weight is only 18 mg. The application of the planar optical technique makes it possible to integrate all passive optical elements onto one transparent substrate. These features are useful for high- speed access, easy optical alignment, mass production, and miniaturization. The design and optical characteristics of the optical tracking sensor are described.

Evanescent field refractometry in planar optical fiber.

PubMed

Holmes, Christopher; Jantzen, Alexander; Gray, Alan C; Gow, Paul C; Carpenter, Lewis G; Bannerman, Rex H S; Gates, James C; Smith, Peter G R

2018-02-15

This Letter demonstrates a refractometer in integrated optical fiber, a new optical platform that planarizes fiber using flame hydrolysis deposition (FHD). The unique advantage of the technology is survivability in harsh environments. The platform is mechanically robust, and can survive elevated temperatures approaching 1000°C and exposure to common solvents, including acetone, gasoline, and methanol. For the demonstrated refractometer, fabrication was achieved through wet etching an SMF-28 fiber to a diameter of 8 μm before FHD planarization. An external refractive index was monitored using fiber Bragg gratings (FBGs), written into the core of the planarized fiber. A direct comparison to alternative FBG refractometers is made, for which the developed platform is shown to have comparable sensitivity, with the added advantage of survivability in harsh environments.

Planar Imaging of Hydroxyl in a High Temperature, High Pressure Combustion Facility

NASA Technical Reports Server (NTRS)

Hicks, Yolanda R.; Locke, Randy J.; Anderson, Robert C.; Ockunzzi, Kelly A.

1995-01-01

An optically accessible flame tube combustor is described which has high temperature, pressure, and air flow capabilities. The windows in the combustor measure 3.8 cm axially by 5.1 cm radially, providing 67 percent optical access to the square cross section flow chamber. The instrumentation allows one to examine combusting flows and combustor subcomponents, such as fuel injectors and air swirlers. These internal combustor subcomponents have previously been studied only with physical probes, such as temperature and species rakes. Planar laser-induced fluorescence (PLIF) images of OH have been obtained from this lean burning combustor burning Jet-A fuel. These images were obtained using various laser excitation lines of the OH A yields X (1,0) band for two fuel injector configurations with pressures ranging from 1013 kPa (10 atm) to 1419 kPa (14 atm), and equivalence ratios from 0.41 to 0. 59. Non-uniformities in the combusting flow, attributed to differences in fuel injector configuration, are revealed by these images.

Multi-pass light amplifier

NASA Technical Reports Server (NTRS)

Plaessmann, Henry (Inventor); Grossman, William M. (Inventor); Olson, Todd E. (Inventor)

1996-01-01

A multiple-pass laser amplifier that uses optical focusing between subsequent passes through a single gain medium so that a reproducibly stable beam size is achieved within the gain region. A resonator or a White Cell cavity is provided, including two or more mirrors (planar or curvilinearly shaped) facing each other along a resonator axis and an optical gain medium positioned on a resonator axis between the mirrors or adjacent to one of the mirrors. In a first embodiment, two curvilinear mirrors, which may include adjacent lenses, are configured so that a light beam passing through the gain medium and incident on the first mirror is reflected by that mirror toward the second mirror in a direction approximately parallel to the resonator axis. A light beam translator, such as an optical flat of transparent material, is positioned to translate this light beam by a controllable amount toward or away from the resonator axis for each pass of the light beam through the translator. A second embodiment uses two curvilinear mirrors and one planar mirror, with a gain medium positioned in the optical path between each curvilinear mirror and the planar mirror. A third embodiment uses two curvilinear mirrors and two planar mirrors, with a gain medium positioned adjacent to a planar mirror. A fourth embodiment uses a curvilinear mirror and three planar mirrors, with a gain medium positioned adjacent to a planar mirror. A fourth embodiment uses four planar mirrors and a focusing lens system, with a gain medium positioned between the four mirrors. A fifth embodiment uses first and second planar mirrors, a focusing lens system and a third mirror that may be planar or curvilinear, with a gain medium positioned adjacent to the third mirror. A sixth embodiment uses two planar mirrors and a curvilinear mirror and a fourth mirror that may be planar or curvilinear, with a gain medium positioned adjacent to the fourth mirror. In a seventh embodiment, first and second mirrors face a third mirror, all curvilinear, in a White Cell configuration, and a gain medium is positioned adjacent to one of the mirrors.

Low-Cost Fiber Optic Pressure Sensor

DOEpatents

Sheem, Sang K.

2004-05-18

The size and cost of fabricating fiber optic pressure sensors is reduced by fabricating the membrane of the sensor in a non-planar shape. The design of the sensors may be made in such a way that the non-planar membrane becomes a part of an air-tight cavity, so as to make the membrane resilient due to the air-cushion effect of the air-tight cavity. Such non-planar membranes are easier to make and attach.

Low-Cost Fiber Optic Pressure Sensor

DOEpatents

Sheem, Sang K.

2003-07-22

The size and cost of fabricating fiber optic pressure sensors is reduced by fabricating the membrane of the sensor in a non-planar shape. The design of the sensors may be made in such a way that the non-planar membrane becomes a part of an air-tight cavity, so as to make the membrane resilient due to the air-cushion effect of the air-tight cavity. Such non-planar membranes are easier to make and attach.

The hybrid photonic planar integrated receiver with a polymer optical waveguide

NASA Astrophysics Data System (ADS)

Busek, Karel; Jerábek, Vitezslav; Armas Arciniega, Julio; Prajzler, Václav

2008-11-01

This article describes design of the photonic receiver composed of the system polymer planar waveguides, InGaAs p-i-n photodiode and integrated HBT amplifier on a low loss composite substrate. The photonic receiver was the main part of the hybrid integrated microwave optoelectronic transceiver TRx (transciever TRx) for the optical networks PON (passive optical networks) with FTTH (fiber-to-the-home) topology. In this article are presented the research results of threedimensional field between output facet of a optical waveguide and p-i-n photodiode. In terms of our research, there was optimized the optical coupling among the facet waveguide and pi-n photodiode and the electrical coupling among p-i-n photodiode and input of HBT amplifier. The hybrid planar lightwave circuit (PLC) of the transceiver TRx will be composed from a two parts - polymer optical waveguide including VHGT filter section and a optoelectronic microwave section.

Predicting optical and thermal characteristics of transparent single-glazed domed skylights

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

Laouadi, A.; Atif, M.R.

1999-07-01

Optical and thermal characteristics of domed skylights are important to solve the trade-off between daylighting and thermal design. However, there is a lack of daylighting and thermal design tools for domed skylights. Optical and thermal characteristics of transparent single-glazed hemispherical domed skylights under sun and sky light are evaluated based on an optical model for domed skylights. The optical model is based on tracing the beam and diffuse radiation transmission through the dome surface. A simple method is proposed to replace single-glazed hemispherical domed skylights by optically and thermally equivalent single-glazed planar skylights to accommodate limitations of energy computer programs.more » Under sunlight, single-glazed hemispherical domed skylights yield slightly lower equivalent solar transmittance and solar heat gain coefficient (SHGC) at near normal zenith angles than those of single-glazed planar skylights. However, single-glazed hemispherical domed skylights yield substantially higher equivalent solar transmittance and SHGC at high zenith angles and around the horizon. Under isotropic skylight, single-glazed hemispherical domed skylights yield slightly lower equivalent solar transmittance and SHGC than those of single-glazed planar skylights. Daily solar heat gains of single-glazed hemispherical domed skylights are higher than those of single-glazed horizontal planar skylights in both winter and summer. In summer, the solar heat gain of single-glazed hemispherical domed skylights can reach 3% to 9% higher than those of horizontal single-glazed planar skylights for latitudes varying between 0 and 55{degree} (north/south). In winter, however, the solar heat gains of single-glazed hemispherical domed skylights increase significantly with the increase of the site latitude and can reach 232% higher than those of horizontal single-glazed planar skylights, particularly for high latitude countries.« less

Design methodology for micro-discrete planar optics with minimum illumination loss for an extended source.

PubMed

Shim, Jongmyeong; Park, Changsu; Lee, Jinhyung; Kang, Shinill

2016-08-08

Recently, studies have examined techniques for modeling the light distribution of light-emitting diodes (LEDs) for various applications owing to their low power consumption, longevity, and light weight. The energy mapping technique, a design method that matches the energy distributions of an LED light source and target area, has been the focus of active research because of its design efficiency and accuracy. However, these studies have not considered the effects of the emitting area of the LED source. Therefore, there are limitations to the design accuracy for small, high-power applications with a short distance between the light source and optical system. A design method for compensating for the light distribution of an extended source after the initial optics design based on a point source was proposed to overcome such limits, but its time-consuming process and limited design accuracy with multiple iterations raised the need for a new design method that considers an extended source in the initial design stage. This study proposed a method for designing discrete planar optics that controls the light distribution and minimizes the optical loss with an extended source and verified the proposed method experimentally. First, the extended source was modeled theoretically, and a design method for discrete planar optics with the optimum groove angle through energy mapping was proposed. To verify the design method, design for the discrete planar optics was achieved for applications in illumination for LED flash. In addition, discrete planar optics for LED illuminance were designed and fabricated to create a uniform illuminance distribution. Optical characterization of these structures showed that the design was optimal; i.e., we plotted the optical losses as a function of the groove angle, and found a clear minimum. Simulations and measurements showed that an efficient optical design was achieved for an extended source.

Applied optics. Multiwavelength achromatic metasurfaces by dispersive phase compensation.

PubMed

Aieta, Francesco; Kats, Mikhail A; Genevet, Patrice; Capasso, Federico

2015-03-20

The replacement of bulk refractive optical elements with diffractive planar components enables the miniaturization of optical systems. However, diffractive optics suffers from large chromatic aberrations due to the dispersion of the phase accumulated by light during propagation. We show that this limitation can be overcome with an engineered wavelength-dependent phase shift imparted by a metasurface, and we demonstrate a design that deflects three wavelengths by the same angle. A planar lens without chromatic aberrations at three wavelengths is also presented. Our designs are based on low-loss dielectric resonators, which introduce a dense spectrum of optical modes to enable dispersive phase compensation. The suppression of chromatic aberrations in metasurface-based planar photonics will find applications in lightweight collimators for displays, as well as chromatically corrected imaging systems. Copyright © 2015, American Association for the Advancement of Science.

Photonic-crystal membranes for optical detection of single nano-particles, designed for biosensor application.

PubMed

Grepstad, Jon Olav; Kaspar, Peter; Solgaard, Olav; Johansen, Ib-Rune; Sudbø, Aasmund S

2012-03-26

A sensor designed to detect bio-molecules is presented. The sensor exploits a planar 2D photonic crystal (PC) membrane with sub-micron thickness and through holes, to induce high optical fields that allow detection of nano-particles smaller than the diffraction limit of an optical microscope. We report on our design and fabrication of a PC membrane with a nano-particle trapped inside. We have also designed and built an imaging system where an optical microscope and a CCD camera are used to take images of the PC membrane. Results show how the trapped nano-particle appears as a bright spot in the image. In a first experimental realization of the imaging system, single particles with a radius of 75 nm can be detected.

Coupling Ideality of Integrated Planar High-Q Microresonators

NASA Astrophysics Data System (ADS)

Pfeiffer, Martin H. P.; Liu, Junqiu; Geiselmann, Michael; Kippenberg, Tobias J.

2017-02-01

Chip-scale optical microresonators with integrated planar optical waveguides are useful building blocks for linear, nonlinear, and quantum-optical photonic devices alike. Loss reduction through improving fabrication processes results in several integrated microresonator platforms attaining quality (Q ) factors of several millions. Beyond the improvement of the quality factor, the ability to operate the microresonator with high coupling ideality in the overcoupled regime is of central importance. In this regime, the dominant source of loss constitutes the coupling to a single desired output channel, which is particularly important not only for quantum-optical applications such as the generation of squeezed light and correlated photon pairs but also for linear and nonlinear photonics. However, to date, the coupling ideality in integrated photonic microresonators is not well understood, in particular, design-dependent losses and their impact on the regime of high ideality. Here we investigate design-dependent parasitic losses described by the coupling ideality of the commonly employed microresonator design consisting of a microring-resonator waveguide side coupled to a straight bus waveguide, a system which is not properly described by the conventional input-output theory of open systems due to the presence of higher-order modes. By systematic characterization of multimode high-Q silicon nitride microresonator devices, we show that this design can suffer from low coupling ideality. By performing 3D simulations, we identify the coupling to higher-order bus waveguide modes as the dominant origin of parasitic losses which lead to the low coupling ideality. Using suitably designed bus waveguides, parasitic losses are mitigated with a nearly unity ideality and strong overcoupling (i.e., a ratio of external coupling to internal resonator loss rate >9 ) are demonstrated. Moreover, we find that different resonator modes can exchange power through the coupler, which, therefore, constitutes a mechanism that induces modal coupling, a phenomenon known to distort resonator dispersion properties. Our results demonstrate the potential for significant performance improvements of integrated planar microresonators for applications in quantum optics and nonlinear photonics achievable by optimized coupler designs.

Optical sensor in planar configuration based on multimode interference

NASA Astrophysics Data System (ADS)

Blahut, Marek

2017-08-01

In the paper a numerical analysis of optical sensors based on multimode interference in planar one-dimensional step-index configuration is presented. The structure consists in single-mode input and output waveguides and multimode waveguide which guide only few modes. Material parameters discussed refer to a SU8 polymer waveguide on SiO2 substrate. The optical system described will be designed to the analysis of biological substances.

Optical chirality in AgCl-Ag thin films through formation of laser-induced planar crossed-chain nanostructures

NASA Astrophysics Data System (ADS)

Nahal, Arashmid; Kashani, Somayeh

2017-09-01

Irradiation of AgCl-Ag thin films by a linearly polarized He-Ne laser beam results in the formation of self-organized periodic nanostructures. As a result of secondary irradiation of the initially exposed sample by the same linearly polarized He-Ne laser beam, but with different orientations of polarization, a complex crossed-chain nanostructure forms. We found that such a complex nanostructure has noticeable chirality and increased optical anisotropy, resulting in optical activity of the sample. Double exposure produces two gratings, crossing each other with angle α, which leads to the formation of crossed building blocks with chiroptical effects. It is established that the amount and the sign of the angle between the two laser-induced gratings (±α) determine the amount and the direction of rotation of the linearly polarized probe beam, respectively. We have also observed an induced anisotropy-dependent ellipticity for the probe light, which is passed through the sample. It is shown that the amount of ellipticity depends on the angle α.

Planar microlens with front-face angle: design, fabrication, and characterization

NASA Astrophysics Data System (ADS)

Al Hafiz, Md. Abdullah; Michael, Aron; Kwok, Chee-Yee

2016-07-01

This paper studies the effect of microlens front-face angle on the performance of an optical system consisting of a planar-graded refractive index (GRIN) lens pair facing each other separated by a free-space region. The planar silica microlens pairs are designed to facilitate low-loss optical signal propagation in the free-space region between the opposing optical waveguides. The planar lens is fabricated from a 38-μm-thick fluorine-doped silica layer on a silicon substrate. It has a parabolic refractive index profile in the vertical direction, which is achieved by controlled fluorine incorporation in the silica film to collimate the optical beam in the vertical direction. Horizontal beam collimation is achieved by incorporating a horizontal curvature at the front face of the lens defined by deep oxide etch. A generalized 3×3 ABCDGH transformation matrix method has been derived to compute the coupling efficiency of such microlens pairs to take front-face angles that may be present due to fabrication variations or limitations and possible input/output optical fiber offset/tilt into considerations. Pairs of such planar GRIN lens with various free-space propagation distances between them ranging from 75 to 2500 μm and with front-face angles of 1.5 deg, 2 deg, and 4 deg have been fabricated and characterized. Beam propagation method simulations have been carried out to substantiate the theoretical and experimental results. The results indicate that the optical loss is reasonably low up to 1.5 deg of front-face angles and increases significantly with further increase in the front-face angle. Analysis shows that for a given system with specific microlens front-face angle, the optical loss can be significantly reduced by properly compensating the vertical position of the input and output fibers.

Backscatter analysis of dihedral corner reflectors using physical optics and the physical theory of diffraction

NASA Technical Reports Server (NTRS)

Griesser, Timothy; Balanis, Constantine A.

1987-01-01

The backscatter cross-sections of dihedral corner reflectors in the azimuthal plane are presently determined by both physical optics (PO) and the physical theory of diffraction (PTD), yielding results for the vertical and horizontal polarizations. In the first analysis method used, geometrical optics is used in place of PO at initial reflections in order to maintain the planar character of the reflected wave and reduce the complexity of the analysis. In the second method, PO is used at almost every reflection in order to maximize the accuracy of the PTD solution at the expense of a rapid increase in complexity. Induced surface current densities and resulting cross section patterns are illustrated for the two methods.

A planar chiral meta-surface for optical vortex generation and focusing

PubMed Central

Ma, Xiaoliang; Pu, Mingbo; Li, Xiong; Huang, Cheng; Wang, Yanqin; Pan, Wenbo; Zhao, Bo; Cui, Jianhua; Wang, Changtao; Zhao, ZeYu; Luo, Xiangang

2015-01-01

Data capacity is rapidly reaching its limit in modern optical communications. Optical vortex has been explored to enhance the data capacity for its extra degree of freedom of angular momentum. In traditional means, optical vortices are generated using space light modulators or spiral phase plates, which would sharply decrease the integration of optical communication systems. Here we experimentally demonstrate a planar chiral antenna array to produce optical vortex from a circularly polarized light. Furthermore, the antenna array has the ability to focus the incident light into point, which greatly increases the power intensity of the generated optical vortex. This chiral antenna array may have potential application in highly integrated optical communication systems. PMID:25988213

Development of Planar Optics for an Optical Tracking Sensor

NASA Astrophysics Data System (ADS)

Kawano, Hiroyuki; Sasagawa, Tomohiro

1998-10-01

An optical tracking sensor for large-capacity flexible disk drive (FDD) is demonstrated. The passive optics is compact and lightweight (5.4 mm length×3.6 mm width×1.2 mm height in size and 18 mg weight). It comprises all passive optical elements necessary for optical tracking, e.g., a focusing lens, a three-beam grating, an aperture and a beam splitter grating. Three beams were focused to a predetermined spot size of 13 µm at designed intervals of 110 µm on a disk surface and the reflected beams were successfully guided to photodiodes. This confirms that the application of the planar optical technique is very useful for realizing a compact and light optical sensor.

Flow-graph approach for optical analysis of planar structures.

PubMed

Minkov, D

1994-11-20

The flow-graph approach (FGA) is applied to optical analysis of isotropic stratified planar structures (ISPS's) at inclined light incidence. Conditions for the presence of coherent and noncoherent light interaction within ISPS's are determined. Examples of the use of FGA for calculation of the transmission and the reflection of two-layer ISPS's for different types of light interaction are given. The advantages of the use of FGA for optical analysis of ISPS's are discussed.

FIBER AND INTEGRATED OPTICS: Reflection of electromagnetic radiation from a multilayer waveguide structure with an absorbing metal layer

NASA Astrophysics Data System (ADS)

Chernushich, A. P.; Shkerdin, G. N.; Shukin, Yu M.

1992-10-01

The angular distribution of the reflection coefficient of an asymmetric multilayer planar structure containing a thin metal film and a planar optical waveguide has been found by accurate numerical calculations. There are resonances in the reflection coefficient associated with hybrid modes of the structure. The cases of strong and weak coupling of the surface polariton modes with the waveguide modes are discussed. The results of the numerical analysis agree with solutions of Maxwell's equations for a multilayer planar structure.

Light emission of heavily doped AlGaN structures under optical pumping

NASA Astrophysics Data System (ADS)

Bokhan, P. A.; Fateev, N. V.; Osinnykh, I. V.; Malin, T. V.; Zakrevsky, Dm. E.; Zhuravlev, K. S.; Wei, Xin; Li, Jian; Chen, Lianghui

2018-04-01

Spectral, temporal and polarization characteristics of spontaneous and stimulated luminescence of Al0.5Ga0.5N/AlN structures grown by molecular beam epitaxy were studied at the optical pulsed pumping with λ = 266 nm. Samples with a high degree of silicon doping were investigated. The vast majority of radiation falls on transitions within the band gap between the levels of defects. As a result, the radiation band embracing the whole visible range of more than 300 THz is observed in both spontaneous radiation and induced luminescence. In spontaneous radiation the band has a smooth spectral intensity distribution over the wavelengths, whereas induced radiation has its sharp peaks corresponding to the mode structure of the planar waveguide. The measured gain of the active medium is g ≈ 70 cm‑1 for a weak signal.

Thermal Casimir and Casimir–Polder interactions in N parallel 2D Dirac materials

NASA Astrophysics Data System (ADS)

Khusnutdinov, Nail; Kashapov, Rashid; Woods, Lilia M.

2018-07-01

The Casimir and Casimir–Polder interactions are investigated in a stack of equally spaced graphene layers. The optical response of the individual graphene is taken into account using gauge invariant components of the polarization tensor extended to the whole complex frequency plane. The planar symmetry for the electromagnetic boundary conditions is further used to obtain explicit forms for the Casimir energy stored in the stack and the Casimir–Polder energy between an atom above the stack. Our calculations show that these fluctuation induced interactions experience strong thermal effects due to the graphene Dirac-like energy spectrum. The spatial dispersion and temperature dependence in the optical response are also found to be important for enhancing the interactions especially at smaller separations. Analytical expressions for low and high temperature limits and their comparison with corresponding expressions for an infinitely conducting planar stack are further used to expand our understanding of Casimir and Casimir–Polder energies in Dirac materials. Our results may be useful to experimentalists as new ways to probe thermal effects at the nanoscale in such universal interactions.

The near-infrared waveguide properties of an LGS crystal formed by swift Kr8+ ion irradiation

NASA Astrophysics Data System (ADS)

Zhou, Yu-Fan; Liu, Peng; Liu, Tao; Zhang, Lian; Sun, Jian-Rong; Wang, Zhi-Guang; Wang, Xue-Lin

2013-11-01

In this work, we report on the optical properties in the near-infrared region of a LGS crystal planar waveguide formed by swift heavy ion irradiation. The planar optical waveguide in a LGS crystal was fabricated by 330 MeV Kr8+-ion implantation at a fluence of 1 × 1012 cm-2. The initial beam had an energy of 2.1 GeV and was slowed down by passing it through a 259 μm thick Al foil. The guided mode was measured using a prism coupler at a wavelength of 1539 nm. The near-field intensity distribution of the mode was recorded by a CCD camera using the end-face coupling method. The FD-BPM was used to simulate the guided mode profile. The lattice damage induced by SHI irradiation in the LGS crystal was studied using micro-Raman spectroscopy. The Raman spectra are consistent with the stopping power distributions of the Kr8+ ions simulated by SRIM and with the micro-photograph of the waveguide taken by a microscope using polarized light.

Optical coupling of bare optoelectronic components and flexographically printed polymer waveguides in planar optronic systems

NASA Astrophysics Data System (ADS)

Wang, Yixiao; Wolfer, Tim; Lange, Alex; Overmeyer, Ludger

2016-05-01

Large scale, planar optronic systems allowing spatially distributed functionalities can be well used in diverse sensor networks, such as for monitoring the environment by measuring various physical quantities in medicine or aeronautics. In these systems, mechanically flexible and optically transparent polymeric foils, e.g. polymethyl methacrylate (PMMA) and polyethylene terephthalate (PET), are employed as carrier materials. A benefit of using these materials is their low cost. The optical interconnections from light sources to light transmission structures in planar optronic systems occupy a pivotal position for the sensing functions. As light sources, we employ the optoelectronic components, such as edgeemitting laser diodes, in form of bare chips, since their extremely small structures facilitate a high integration compactness and ensure sufficient system flexibility. Flexographically printed polymer optical waveguides are deployed as light guiding structures for short-distance communication in planar optronic systems. Printing processes are utilized for this generation of waveguides to achieve a cost-efficient large scale and high-throughput production. In order to attain a high-functional optronic system for sensing applications, one of the most essential prerequisites is the high coupling efficiency between the light sources and the waveguides. Therefore, in this work, we focus on the multimode polymer waveguide with a parabolic cross-section and investigate its optical coupling with the bare laser diode. We establish the geometrical model of the alignment based on the previous works on the optodic bonding of bare laser diodes and the fabrication process of polymer waveguides with consideration of various parameters, such as the beam profile of the laser diode, the employed polymer properties of the waveguides as well as the carrier substrates etc. Accordingly, the optical coupling of the bare laser diodes and the polymer waveguides was simulated. Additionally, we demonstrate optical links by adopting the aforementioned processes used for defining the simulation. We verify the feasibility of the developed processes for planar optronic systems by using an active alignment and conduct discussions for further improvements of optical alignment.

Organic light-emitting diodes from homoleptic square planar complexes

DOEpatents

Omary, Mohammad A

2013-11-12

Homoleptic square planar complexes [M(N.LAMBDA.N).sub.2], wherein two identical N.LAMBDA.N bidentate anionic ligands are coordinated to the M(II) metal center, including bidentate square planar complexes of triazolates, possess optical and electrical properties that make them useful for a wide variety of optical and electrical devices and applications. In particular, the complexes are useful for obtaining white or monochromatic organic light-emitting diodes ("OLEDs"). Improved white organic light emitting diode ("WOLED") designs have improved efficacy and/or color stability at high brightness in single- or two-emitter white or monochrome OLEDs that utilize homoleptic square planar complexes, including bis[3,5-bis(2-pyridyl)-1,2,4-triazolato]platinum(II) ("Pt(ptp).sub.2").

Transparent selective illumination means suitable for use in optically activated electrical switches and optically activated electrical switches constructed using same

DOEpatents

Wilcox, R.B.

1991-09-10

A planar transparent light conducting means and an improved optically activated electrical switch made using the novel light conducting means are disclosed. The light conducting means further comprise light scattering means on one or more opposite planar surfaces thereof to transmit light from the light conducting means into adjacent media and reflective means on other surfaces of the light conducting means not containing the light scattering means. The optically activated electrical switch comprises at least two stacked photoconductive wafers, each having electrodes formed on both surfaces thereof, and separated by the planar transparent light conducting means. The light scattering means on the light conducting means face surfaces of the wafers not covered by the electrodes to transmit light from the light conducting means into the photoconductive wafers to uniformly illuminate and activate the switch. 11 figures.

Quantum electromechanics on silicon nitride nanomembranes

PubMed Central

Fink, J. M.; Kalaee, M.; Pitanti, A.; Norte, R.; Heinzle, L.; Davanço, M.; Srinivasan, K.; Painter, O.

2016-01-01

Radiation pressure has recently been used to effectively couple the quantum motion of mechanical elements to the fields of optical or microwave light. Integration of all three degrees of freedom—mechanical, optical and microwave—would enable a quantum interconnect between microwave and optical quantum systems. We present a platform based on silicon nitride nanomembranes for integrating superconducting microwave circuits with planar acoustic and optical devices such as phononic and photonic crystals. Using planar capacitors with vacuum gaps of 60 nm and spiral inductor coils of micron pitch we realize microwave resonant circuits with large electromechanical coupling to planar acoustic structures of nanoscale dimensions and femtoFarad motional capacitance. Using this enhanced coupling, we demonstrate microwave backaction cooling of the 4.48 MHz mechanical resonance of a nanobeam to an occupancy as low as 0.32. These results indicate the viability of silicon nitride nanomembranes as an all-in-one substrate for quantum electro-opto-mechanical experiments. PMID:27484751

Quantum electromechanics on silicon nitride nanomembranes.

PubMed

Fink, J M; Kalaee, M; Pitanti, A; Norte, R; Heinzle, L; Davanço, M; Srinivasan, K; Painter, O

2016-08-03

Radiation pressure has recently been used to effectively couple the quantum motion of mechanical elements to the fields of optical or microwave light. Integration of all three degrees of freedom-mechanical, optical and microwave-would enable a quantum interconnect between microwave and optical quantum systems. We present a platform based on silicon nitride nanomembranes for integrating superconducting microwave circuits with planar acoustic and optical devices such as phononic and photonic crystals. Using planar capacitors with vacuum gaps of 60 nm and spiral inductor coils of micron pitch we realize microwave resonant circuits with large electromechanical coupling to planar acoustic structures of nanoscale dimensions and femtoFarad motional capacitance. Using this enhanced coupling, we demonstrate microwave backaction cooling of the 4.48 MHz mechanical resonance of a nanobeam to an occupancy as low as 0.32. These results indicate the viability of silicon nitride nanomembranes as an all-in-one substrate for quantum electro-opto-mechanical experiments.

Transparent selective illumination means suitable for use in optically activated electrical switches and optically activated electrical switches constructed using same

DOEpatents

Wilcox, Russell B.

1991-01-01

A planar transparent light conducting means and an improved optically activated electrical switch made using the novel light conducting means are disclosed. The light conducting means further comprise light scattering means on one or more opposite planar surfaces thereof to transmit light from the light conducting means into adjacent media and reflective means on other surfaces of the light conducting means not containing the light scattering means. The optically activated electrical switch comprises at least two stacked photoconductive wafers, each having electrodes formed on both surfaces thereof, and separated by the planar transparent light conducting means. The light scattering means on the light conducting means face surfaces of the wafers not covered by the electrodes to transmit light from the light conducting means into the photoconductive wafers to uniformly illuminate and activate the switch.

The concave iris in pigment dispersion syndrome.

PubMed

Liu, Lance; Ong, Ee Lin; Crowston, Jonathan

2011-01-01

To visualize the changes of the iris contour in patients with pigment dispersion syndrome after blinking, accommodation, and pharmacologic miosis using anterior segment optical coherence tomography. Observational case series. A total of 33 eyes of 20 patients with pigment dispersion syndrome. Each eye was imaged along the horizontal 0- to 180-degree meridian using the Visante Anterior Segment Imaging System (Carl Zeiss Meditec, Dublin, CA). Scans were performed at baseline and after focusing on an internal fixation target for 5 minutes, forced blinking, accommodation, and pharmacologic miosis with pilocarpine 2%. Quantitative analysis of the changes in the iris configuration. After 5 minutes of continual fixation, the iris became planar with the mean ± standard deviation curvature decreasing from 214 ± 74 μm to 67 ± 76 μm (P < 0.05). The iris remained planar in all patients with pigment dispersion syndrome after forced blinking, but the iris concavity recovered to 227 ± 113 μm (P = 0.34) and 238 ± 119 μm (P = 0.19) with the -3.0 and -6.0 diopter lenses, respectively. Pilocarpine-induced miosis caused the iris to assume a planar configuration in all subjects. This study shows that the iris in pigment dispersion syndrome assumes a planar configuration when fixating and that the concavity of the iris surface is not restored by blinking. Accommodation restored the iris concavity, suggesting that the posterior curvature of the iris in pigment dispersion syndrome is induced and probably maintained, at least in part, by accommodation. Copyright © 2011 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.

Optical absorption in planar graphene superlattice: The role of structural parameters

NASA Astrophysics Data System (ADS)

Azadi, L.; Shojaei, S.

2018-04-01

We theoretically studied the optically driven interband transitions in a planar graphene superlattices (PGSL) formed by patterning graphene sheet on laterally hetrostructured substrate as Sio2/hBN. A tunable optical transitions between minibands is observed based on engineering structural parameters. We derive analytically expression for optical absorption from two-band model. Considerable optical absorption is obtained for different ratios between widths of heterostructured substrate and is explained analytically from the view point of wavefunction engineering and miniband dispersion, in details. The role of different statuses of polarization as circular and linear are considered. Our study paves a way toward the control of optical properties of PGSLs to be implemented in optoelectronics devices.

Planar dielectric waveguides in rotation are optical fibers: comparison with the classical model.

PubMed

Peña García, Antonio; Pérez-Ocón, Francisco; Jiménez, José Ramón

2008-01-21

A novel and simpler method to calculate the main parameters in fiber optics is presented. This method is based in a planar dielectric waveguide in rotation and, as an example, it is applied to calculate the turning points and the inner caustic in an optical fiber with a parabolic refractive index. It is shown that the solution found using this method agrees with the standard (and more complex) method, whose solutions for these points are also summarized in this paper.

Efficient high-power frequency doubling of distributed Bragg reflector tapered laser radiation in a periodically poled MgO-doped lithium niobate planar waveguide.

PubMed

Jedrzejczyk, Daniel; Güther, Reiner; Paschke, Katrin; Jeong, Woo-Jin; Lee, Han-Young; Erbert, Götz

2011-02-01

We report on efficient single-pass, high-power second-harmonic generation in a periodically poled MgO-doped LiNbO3 planar waveguide using a distributed Bragg reflector tapered diode laser as a pump source. A coupling efficiency into the planar waveguide of 73% was realized, and 1.07 W of visible laser light at 532 nm was generated. Corresponding optical and electro-optical conversion efficiencies of 26% and 8.4%, respectively, were achieved. Good agreement between the experimental data and the theoretical predictions was observed.

Chiral optical response of planar and symmetric nanotrimers enabled by heteromaterial selection.

PubMed

Banzer, Peter; Woźniak, Paweł; Mick, Uwe; De Leon, Israel; Boyd, Robert W

2016-10-13

Chirality is an intriguing property of certain molecules, materials or artificial nanostructures, which allows them to interact with the spin angular momentum of the impinging light field. Due to their chiral geometry, they can distinguish between left- and right-hand circular polarization states or convert them into each other. Here we introduce an approach towards optical chirality, which is observed in individual two-dimensional and geometrically mirror-symmetric nanostructures. In this scheme, the chiral optical response is induced by the chosen heterogeneous material composition of a particle assembly and the corresponding resonance behaviour of the constituents it is built from, which breaks the symmetry of the system. As a proof of principle, we investigate such a structure composed of individual silicon and gold nanoparticles both experimentally, as well as numerically. Our proposed concept constitutes an approach for designing two-dimensional chiral media tailored at the nanoscale, allowing for high tunability of their optical response.

Quantitative separation of the anisotropic magnetothermopower and planar Nernst effect by the rotation of an in-plane thermal gradient

NASA Astrophysics Data System (ADS)

Reimer, Oliver; Meier, Daniel; Bovender, Michel; Helmich, Lars; Dreessen, Jan-Oliver; Krieft, Jan; Shestakov, Anatoly S.; Back, Christian H.; Schmalhorst, Jan-Michael; Hütten, Andreas; Reiss, Günter; Kuschel, Timo

2017-01-01

A thermal gradient as the driving force for spin currents plays a key role in spin caloritronics. In this field the spin Seebeck effect (SSE) is of major interest and was investigated in terms of in-plane thermal gradients inducing perpendicular spin currents (transverse SSE) and out-of-plane thermal gradients generating parallel spin currents (longitudinal SSE). Up to now all spincaloric experiments employ a spatially fixed thermal gradient. Thus, anisotropic measurements with respect to well defined crystallographic directions were not possible. Here we introduce a new experiment that allows not only the in-plane rotation of the external magnetic field, but also the rotation of an in-plane thermal gradient controlled by optical temperature detection. As a consequence, the anisotropic magnetothermopower and the planar Nernst effect in a permalloy thin film can be measured simultaneously. Thus, the angular dependence of the magnetothermopower with respect to the magnetization direction reveals a phase shift, that allows the quantitative separation of the thermopower, the anisotropic magnetothermopower and the planar Nernst effect.

Three-Dimensional Self-Organization in Nanocomposite Layered Systems by Ultrafast Laser Pulses.

PubMed

Liu, Zeming; Siegel, Jan; Garcia-Lechuga, Mario; Epicier, Thierry; Lefkir, Yaya; Reynaud, Stéphanie; Bugnet, Matthieu; Vocanson, Francis; Solis, Javier; Vitrant, Guy; Destouches, Nathalie

2017-05-23

Controlling plasmonic systems with nanometer resolution in transparent films and their colors over large nonplanar areas is a key issue for spreading their use in various industrial fields. Using light to direct self-organization mechanisms provides high-speed and flexible processes to meet this challenge. Here, we describe a route for the laser-induced self-organization of metallic nanostructures in 3D. Going beyond the production of planar nanopatterns, we demonstrate that ultrafast laser-induced excitation combined with nonlinear feedback mechanisms in a nanocomposite thin film can lead to 3D self-organized nanostructured films. The process, which can be extended to complex layered composite systems, produces highly uniform large-area nanopatterns. We show that 3D self-organization originates from the simultaneous excitation of independent optical modes at different depths in the film and is activated by the plasmon-induced charge separation and thermally induced NP growth mechanisms. This laser color marking technique enables multiplexed optical image encoding and the generated nanostructured Ag NPs:TiO 2 films offer great promise for applications in solar energy harvesting, photocatalysis, or photochromic devices.

Adiabatic Field-Free Alignment of Asymmetric Top Molecules with an Optical Centrifuge.

PubMed

Korobenko, A; Milner, V

2016-05-06

We use an optical centrifuge to align asymmetric top SO_{2} molecules by adiabatically spinning their most polarizable O-O axis. The effective centrifugal potential in the rotating frame confines the sulfur atoms to the plane of the laser-induced rotation, leading to the planar molecular alignment that persists after the molecules are released from the centrifuge. The periodic appearance of the full three-dimensional alignment, typically observed only with linear and symmetric top molecules, is also detected. Together with strong in-plane centrifugal forces, which bend the molecules by up to 10 deg, permanent field-free alignment offers new ways of controlling molecules with laser light.

Recent progress in design and hybridization of planar grating-based transceivers

NASA Astrophysics Data System (ADS)

Bidnyk, S.; Pearson, M.; Balakrishnan, A.; Gao, M.

2007-06-01

We report on recent progress in simulations, physical layout, fabrication and hybridization of planar grating-based transceivers for passive optical networks (PONs). Until recently, PON transceivers have been manufactured using bulk micro-optical components. Today, advancements in modeling and simulation techniques has made it possible to design complex elements in the same silica-on silicon PLC platform and create an alternative platform for manufacturing of bi-directional transceivers. In our chips we simulated an integrated chip that monolithically combined planar reflective gratings and cascaded Mach-Zehnder interferometers. We used a combination of the finite element method and beam propagation method to model cascaded interferometers with enhanced coupling coefficients. Our simulations show that low-diffraction order planar reflective gratings, designed for small incidence and reflection angles, possess the required dispersion strength to meet the PON specifications. Subsequently, we created structures for passive alignment and hybridized photodetectors and lasers. We believe that advancements in simulation of planar lightwave circuits with embedded planar reflective gratings will result in displacement of the thin-film filters (TFFs) technology in many applications that require a high degree of monolithic and hybrid integration.

Planar laser-induced fluorescence imaging of OH in the exhaust of a bi-propellant thruster

NASA Technical Reports Server (NTRS)

Paul, Phillip H.; Clemens, N. T.; Makel, D. B.

1992-01-01

Planar laser-induced fluorescence imaging of the hydroxyl radical has been performed on the flow produced by the exhaust of a subscale H2/O2 fueled bi-propellant rocket engine. Measurements were made to test the feasibility of OH (0,0) and (3,0) excitation strategies by using injection seeded XeCl and KrF excimer lasers, respectively. The flow is produced with hydrogen and oxygen reacting at a combustor chamber pressure of 5 atm which then exhausts to the ambient. The hydroxyl concentration in the exhaust flow is approximately 8 percent. Fluorescence images obtained by pumping the Q1(3) transition in the (0,0) band exhibited very high signals but also showed the effect of laser beam absorption. To obtain images when pumping the P1(8) transition in the (3,0) band it was necessary to use exceptionally fast imaging optics and unacceptably high intensifier gains. The result was single-shot images which displayed a signal-to-noise ratio of order unity or less when measured on a per pixel basis.

Planar laser-induced fluorescence imaging of OH in the exhaust of a bi-propellant thruster

NASA Astrophysics Data System (ADS)

Paul, Phillip H.; Clemens, N. T.; Makel, D. B.

1992-09-01

Planar laser-induced fluorescence imaging of the hydroxyl radical has been performed on the flow produced by the exhaust of a subscale H2/O2 fueled bi-propellant rocket engine. Measurements were made to test the feasibility of OH (0,0) and (3,0) excitation strategies by using injection seeded XeCl and KrF excimer lasers, respectively. The flow is produced with hydrogen and oxygen reacting at a combustor chamber pressure of 5 atm which then exhausts to the ambient. The hydroxyl concentration in the exhaust flow is approximately 8 percent. Fluorescence images obtained by pumping the Q1(3) transition in the (0,0) band exhibited very high signals but also showed the effect of laser beam absorption. To obtain images when pumping the P1(8) transition in the (3,0) band it was necessary to use exceptionally fast imaging optics and unacceptably high intensifier gains. The result was single-shot images which displayed a signal-to-noise ratio of order unity or less when measured on a per pixel basis.

Ink-jet printed fluorescent materials as light sources for planar optical waveguides on polymer foils

NASA Astrophysics Data System (ADS)

Bollgruen, Patrick; Gleissner, Uwe; Wolfer, Tim; Megnin, Christof; Mager, Dario; Overmeyer, Ludger; Korvink, Jan G.; Hanemann, Thomas

2016-10-01

Polymer-based optical sensor networks on foils (planar optronic systems) are a promising research field, but it can be challenging to supply them with light. We present a solvent-free, ink-jet printable material system with optically active substances to create planar light sources for these networks. The ink is based on a UV-curable monomer, the fluorescent agents are EuDBMPhen or 9,10-diphenylantracene, which fluoresce at 612 or 430 nm, respectively. We demonstrate the application as light source by printing a small area of fluorescent material on an optical waveguide fabricated by flexographic printing on PMMA foil, resulting in a simple polymer-optical device fabricated entirely by additive deposition techniques. When excited by a 405-nm laser of 10 mW, the emitted light couples into the waveguide and appears at the end of the waveguide. In comparison to conventional light sources, the intensity is weak but could be detected with a photodiode power sensor. In return, the concept has the advantage of being completely independent of any electrical elements or external cable connections.

Reflective afocal broadband adaptive optics scanning ophthalmoscope

PubMed Central

Dubra, Alfredo; Sulai, Yusufu

2011-01-01

A broadband adaptive optics scanning ophthalmoscope (BAOSO) consisting of four afocal telescopes, formed by pairs of off-axis spherical mirrors in a non-planar arrangement, is presented. The non-planar folding of the telescopes is used to simultaneously reduce pupil and image plane astigmatism. The former improves the adaptive optics performance by reducing the root-mean-square (RMS) of the wavefront and the beam wandering due to optical scanning. The latter provides diffraction limited performance over a 3 diopter (D) vergence range. This vergence range allows for the use of any broadband light source(s) in the 450-850 nm wavelength range to simultaneously image any combination of retinal layers. Imaging modalities that could benefit from such a large vergence range are optical coherence tomography (OCT), multi- and hyper-spectral imaging, single- and multi-photon fluorescence. The benefits of the non-planar telescopes in the BAOSO are illustrated by resolving the human foveal photoreceptor mosaic in reflectance using two different superluminescent diodes with 680 and 796 nm peak wavelengths, reaching the eye with a vergence of 0.76 D relative to each other. PMID:21698035

Reflective afocal broadband adaptive optics scanning ophthalmoscope.

PubMed

Dubra, Alfredo; Sulai, Yusufu

2011-06-01

A broadband adaptive optics scanning ophthalmoscope (BAOSO) consisting of four afocal telescopes, formed by pairs of off-axis spherical mirrors in a non-planar arrangement, is presented. The non-planar folding of the telescopes is used to simultaneously reduce pupil and image plane astigmatism. The former improves the adaptive optics performance by reducing the root-mean-square (RMS) of the wavefront and the beam wandering due to optical scanning. The latter provides diffraction limited performance over a 3 diopter (D) vergence range. This vergence range allows for the use of any broadband light source(s) in the 450-850 nm wavelength range to simultaneously image any combination of retinal layers. Imaging modalities that could benefit from such a large vergence range are optical coherence tomography (OCT), multi- and hyper-spectral imaging, single- and multi-photon fluorescence. The benefits of the non-planar telescopes in the BAOSO are illustrated by resolving the human foveal photoreceptor mosaic in reflectance using two different superluminescent diodes with 680 and 796 nm peak wavelengths, reaching the eye with a vergence of 0.76 D relative to each other.

Planar waveguide microlenses for nonblocking photonic switches and optical interconnects

NASA Astrophysics Data System (ADS)

Glebov, Alexei L.; Huang, Lidu; Lee, Michael; Aoki, Shigenori; Yokouchi, Kishio

2004-09-01

Different types of planar waveguide microlenses are fabricated with PLC technologies from a variety of optical materials such as silica, photo-definable epoxy resins, and a number of other optical polymers. Hybrid microlenses are also fabricated in which the base of the lens, with a double concave gap, is formed from silica and the gap is filled with an optical polymer. The optimized lens structures provide the maximum coupling efficiencies between the input and output channels at distances up to 100 mm with a minimum channel pitch of 0.5-0.7 mm. Experimental and theoretical studies provide results on collimation and focusing properties of single and double microlenses made of silica, polymer, and silica/polymer. The evaluation of the temperature and wavelength effects on the collimation characteristics of the lenses demonstrate that the single lenses are more stable and, thus, more suitable for operations under varying conditions. Examples of the planar waveguide microlens applications are presented. In one application the microlens arrays are integrated in fast electrooptic photonic switching modules. In the other application the microlenses are embedded in the backplanes with nonblocking optical interconnects.

Optical switch

DOEpatents

Reedy, R.P.

1985-01-18

An optical switching device is provided whereby light from a first glass fiber or a second glass fiber may be selectively transmitted into a third glass fiber. Each glass fiber is provided with a focusing and collimating lens system. In one mode of operation, light from the first glass fiber is reflected by a planar mirror into the third glass fiber. In another mode of operation, light from the second glass fiber passes directly into the third glass fiber. The planar mirror is attached to a rotatable table which is rotated to provide the optical switching.

Optical switch

DOEpatents

Reedy, R.P.

1987-11-10

An optical switching device is provided whereby light from a first glass fiber or a second glass fiber may be selectively transmitted into a third glass fiber. Each glass fiber is provided with a focusing and collimating lens system. In one mode of operation, light from the first glass fiber is reflected by a planar mirror into the third glass fiber. In another mode of operation, light from the second glass fiber passes directly into the third glass fiber. The planar mirror is attached to a rotatable table which is rotated to provide the optical switching. 3 figs.

Graphene photonics for resonator-enhanced electro-optic devices and all-optical interactions

DOEpatents

Englund, Dirk R.; Gan, Xuetao

2017-03-21

Techniques for coupling light into graphene using a planar photonic crystal having a resonant cavity characterized by a mode volume and a quality factor and at least one graphene layer positioned in proximity to the planar photonic crystal to at least partially overlap with an evanescent field of the resonant cavity. At least one mode of the resonant cavity can couple into the graphene layer via evanescent coupling. The optical properties of the graphene layer can be controlled, and characteristics of the graphene-cavity system can be detected. Coupling light into graphene can include electro-optic modulation of light, photodetection, saturable absorption, bistability, and autocorrelation.

Femtosecond laser inscription of asymmetric directional couplers for in-fiber optical taps and fiber cladding photonics.

PubMed

Grenier, Jason R; Fernandes, Luís A; Herman, Peter R

2015-06-29

Precise alignment of femtosecond laser tracks in standard single mode optical fiber is shown to enable controllable optical tapping of the fiber core waveguide light with fiber cladding photonic circuits. Asymmetric directional couplers are presented with tunable coupling ratios up to 62% and bandwidths up to 300 nm at telecommunication wavelengths. Real-time fiber monitoring during laser writing permitted a means of controlling the coupler length to compensate for micron-scale alignment errors and to facilitate tailored design of coupling ratio, spectral bandwidth and polarization properties. Laser induced waveguide birefringence was harnessed for polarization dependent coupling that led to the formation of in-fiber polarization-selective taps with 32 dB extinction ratio. This technology enables the interconnection of light propagating in pre-existing waveguides with laser-formed devices, thereby opening a new practical direction for the three-dimensional integration of optical devices in the cladding of optical fibers and planar lightwave circuits.

FIBER AND INTEGRATED OPTICS: Waveguide characteristics of real optical strip waveguides

NASA Astrophysics Data System (ADS)

Shmal'ko, A. V.; Frolov, V. V.

1990-01-01

A study is reported of the influence of the parameters of real thin-film optical strip waveguides on their waveguide characteristics (propagation constants, localization of the mode field, etc.) allowing for the presence of transition layers in a transverse cross section of the base planar waveguide, for the real geometry of this section (which is nearly trapezoidal), and for the thickness of the guiding strip. Analytic expressions are obtained for the optical confinement coefficient and the effective mode format of a weakly guiding symmetric strip waveguide. It is shown that the coefficient representing the fundamental E11x(y) mode is practically independent of the relative thickness t /h (h is the thickness of the base planar waveguide) of the guiding strip provided t /h>=0.5. The corrections to the normalized effective refractive indices of the base planar and strip waveguides are found in order to allow for the real geometry and for the refractive index profile in the strip waveguide.

Direct Electrospray Printing of Gradient Refractive Index Chalcogenide Glass Films.

PubMed

Novak, Spencer; Lin, Pao Tai; Li, Cheng; Lumdee, Chatdanai; Hu, Juejun; Agarwal, Anuradha; Kik, Pieter G; Deng, Weiwei; Richardson, Kathleen

2017-08-16

A spatially varying effective refractive index gradient using chalcogenide glass layers is printed on a silicon wafer using an optimized electrospray (ES) deposition process. Using solution-derived glass precursors, IR-transparent Ge 23 Sb 7 S 70 and As 40 S 60 glass films of programmed thickness are fabricated to yield a bilayer structure, resulting in an effective gradient refractive index (GRIN) film. Optical and compositional analysis tools confirm the optical and physical nature of the gradient in the resulting high-optical-quality films, demonstrating the power of direct printing of multimaterial structures compatible with planar photonic fabrication protocols. The potential application of such tailorable materials and structures as they relate to the enhancement of sensitivity in chalcogenide glass based planar chemical sensor device design is presented. This method, applicable to a broad cross section of glass compositions, shows promise in directly depositing GRIN films with tunable refractive index profiles for bulk and planar optical components and devices.

Generalized fiber Fourier optics.

PubMed

Cincotti, Gabriella

2011-06-15

A twofold generalization of the optical schemes that perform the discrete Fourier transform (DFT) is given: new passive planar architectures are presented where the 2 × 2 3 dB couplers are replaced by M × M hybrids, reducing the number of required connections and phase shifters. Furthermore, the planar implementation of the discrete fractional Fourier transform (DFrFT) is also described, with a waveguide grating router (WGR) configuration and a properly modified slab coupler.

Planar Diffractive Lenses: Fundamentals, Functionalities, and Applications.

PubMed

Huang, Kun; Qin, Fei; Liu, Hong; Ye, Huapeng; Qiu, Cheng-Wei; Hong, Minghui; Luk'yanchuk, Boris; Teng, Jinghua

2018-06-01

Traditional objective lenses in modern microscopy, based on the refraction of light, are restricted by the Rayleigh diffraction limit. The existing methods to overcome this limit can be categorized into near-field (e.g., scanning near-field optical microscopy, superlens, microsphere lens) and far-field (e.g., stimulated emission depletion microscopy, photoactivated localization microscopy, stochastic optical reconstruction microscopy) approaches. However, they either operate in the challenging near-field mode or there is the need to label samples in biology. Recently, through manipulation of the diffraction of light with binary masks or gradient metasurfaces, some miniaturized and planar lenses have been reported with intriguing functionalities such as ultrahigh numerical aperture, large depth of focus, and subdiffraction-limit focusing in far-field, which provides a viable solution for the label-free superresolution imaging. Here, the recent advances in planar diffractive lenses (PDLs) are reviewed from a united theoretical account on diffraction-based focusing optics, and the underlying physics of nanofocusing via constructive or destructive interference is revealed. Various approaches of realizing PDLs are introduced in terms of their unique performances and interpreted by using optical aberration theory. Furthermore, a detailed tutorial about applying these planar lenses in nanoimaging is provided, followed by an outlook regarding future development toward practical applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Design principles for single standing nanowire solar cells: going beyond the planar efficiency limits.

PubMed

Zeng, Yang; Ye, Qinghao; Shen, Wenzhong

2014-05-09

Semiconductor nanowires (NWs) have long been used in photovoltaic applications but restricted to approaching the fundamental efficiency limits of the planar devices with less material. However, recent researches on standing NWs have started to reveal their potential of surpassing these limits when their unique optical property is utilized in novel manners. Here, we present a theoretical guideline for maximizing the conversion efficiency of a single standing NW cell based on a detailed study of its optical absorption mechanism. Under normal incidence, a standing NW behaves as a dielectric resonator antenna, and its optical cross-section shows its maximum when the lowest hybrid mode (HE11δ) is excited along with the presence of a back-reflector. The promotion of the cell efficiency beyond the planar limits is attributed to two effects: the built-in concentration caused by the enlarged optical cross-section, and the shifting of the absorption front resulted from the excited mode profile. By choosing an optimal NW radius to support the HE11δ mode within the main absorption spectrum, we demonstrate a relative conversion-efficiency enhancement of 33% above the planar cell limit on the exemplary a-Si solar cells. This work has provided a new basis for designing and analyzing standing NW based solar cells.

Design principles for single standing nanowire solar cells: going beyond the planar efficiency limits

PubMed Central

Zeng, Yang; Ye, Qinghao; Shen, Wenzhong

2014-01-01

Semiconductor nanowires (NWs) have long been used in photovoltaic applications but restricted to approaching the fundamental efficiency limits of the planar devices with less material. However, recent researches on standing NWs have started to reveal their potential of surpassing these limits when their unique optical property is utilized in novel manners. Here, we present a theoretical guideline for maximizing the conversion efficiency of a single standing NW cell based on a detailed study of its optical absorption mechanism. Under normal incidence, a standing NW behaves as a dielectric resonator antenna, and its optical cross-section shows its maximum when the lowest hybrid mode (HE11δ) is excited along with the presence of a back-reflector. The promotion of the cell efficiency beyond the planar limits is attributed to two effects: the built-in concentration caused by the enlarged optical cross-section, and the shifting of the absorption front resulted from the excited mode profile. By choosing an optimal NW radius to support the HE11δ mode within the main absorption spectrum, we demonstrate a relative conversion-efficiency enhancement of 33% above the planar cell limit on the exemplary a-Si solar cells. This work has provided a new basis for designing and analyzing standing NW based solar cells. PMID:24810591

Temperature-dependent optical properties of gold nanoparticles coated with a charged diblock copolymer and an uncharged triblock copolymer.

PubMed

Volden, Sondre; Kjøniksen, Anna-Lena; Zhu, Kaizheng; Genzer, Jan; Nyström, Bo; Glomm, Wilhelm R

2010-02-23

We demonstrate that the optical properties of gold nanoparticles can be used to detect and follow stimuli-induced changes in adsorbed macromolecules. Specifically, we investigate thermal response of anionic diblock and uncharged triblock copolymers based on poly(N-isopropylacrylamide) (PNIPAAM) blocks adsorbed onto gold nanoparticles and planar gold surfaces in a temperature range between 25 and 60 degrees C. By employing a palette of analytical probes, including UV-visible spectroscopy, dynamic light scattering, fluorescence, and quartz crystal microbalance with dissipation monitoring, we establish that while the anionic copolymer forms monolayers at both low and high temperature, the neutral copolymer adsorbs as a monolayer at low temperatures and forms multilayers above the cloud point (T(C)). Raising the temperature above T(C) severely affects the optical properties of the gold particle/polymer composites, expelling associated water and altering the immediate surroundings of the gold nanoparticles. This effect, stronger for the uncharged polymer, is related to the amount of polymer adsorbed on the surface, where a denser shell influences the surface plasmon band to a greater degree. This is corroborated with light scattering experiments, which reveal that flocculation of the neutral polymer-coated particles occurs at high temperatures. The flocculation behavior of the neutral copolymer on planar gold surfaces results in multilayer formation. The observed effects are discussed within the framework of the Mie-Drude theory.

Catadioptric planar compound eye with large field of view.

PubMed

Deng, Huaxia; Gao, Xicheng; Ma, Mengchao; Li, Yunyang; Li, Hang; Zhang, Jin; Zhong, Xiang

2018-05-14

The planar compound eye has the advantages of simple structure and no requirement for complex relay optical elements, but the field of view (FOV) is very difficult to expand. Overcoming the limitation of FOV, especially with simple structures, is a great challenge for the development of planar compound eyes. Different from the existing designs that only considering refraction, this article proposes a catadioptric planar compound eye based on the reflection and refraction to expand the FOV. In the proposed design, the incident light from a large angle is reflected into the lenslet array by two rotationally symmetric mirrors whose surface equations are optimized by mathematical and optical softwares. The FOV of the proposed catadioptric planar compound eye theoretically can reach 96.6°, which is much wider than the opening record of 70°. Moreover, no distortion of the imaging system can be obtained theoretically in this design. Simulation results show a linearity of better than 99% for the most of the incident angles. The verification experiments show that the FOV of the proposed device can reach 90.7° while the FOV of the corresponding planar compound eye without mirrors is 41.6°. The proposed catadioptric planar compound eye has the great potential in monitoring, detection and virtual reality since the FOV has been widen significantly.

Transmutation of planar media singularities in a conformal cloak.

PubMed

Liu, Yichao; Mukhtar, Musawwadah; Ma, Yungui; Ong, C K

2013-11-01

Invisibility cloaking based on optical transformation involves materials singularity at the branch cut points. Many interesting optical devices, such as the Eaton lens, also require planar media index singularities in their implementation. We show a method to transmute two singularities simultaneously into harmless topological defects formed by anisotropic permittivity and permeability tensors. Numerical simulation is performed to verify the functionality of the transmuted conformal cloak consisting of two kissing Maxwell fish eyes.

Total internal reflection-based planar waveguide solar concentrator with symmetric air prisms as couplers.

PubMed

Xie, Peng; Lin, Huichuan; Liu, Yong; Li, Baojun

2014-10-20

We present a waveguide coupling approach for planar waveguide solar concentrator. In this approach, total internal reflection (TIR)-based symmetric air prisms are used as couplers to increase the coupler reflectivity and to maximize the optical efficiency. The proposed concentrator consists of a line focusing cylindrical lens array over a planar waveguide. The TIR-based couplers are located at the focal line of each lens to couple the focused sunlight into the waveguide. The optical system was modeled and simulated with a commercial ray tracing software (Zemax). Results show that the system used with optimized TIR-based couplers can achieve 70% optical efficiency at 50 × geometrical concentration ratio, resulting in a flux concentration ratio of 35 without additional secondary concentrator. An acceptance angle of ± 7.5° is achieved in the x-z plane due to the use of cylindrical lens array as the primary concentrator.

Planar metasurface retroreflector

NASA Astrophysics Data System (ADS)

Arbabi, Amir; Arbabi, Ehsan; Horie, Yu; Kamali, Seyedeh Mahsa; Faraon, Andrei

2017-07-01

Metasurfaces are two-dimensional arrangements of subwavelength scatterers that control the propagation of optical waves. Here, we show that cascaded metasurfaces, each performing a predefined mathematical transformation, provide a new optical design framework that enables new functionalities not yet demonstrated with single metasurfaces. Specifically, we demonstrate that retroreflection can be achieved with two vertically stacked planar metasurfaces, the first performing a spatial Fourier transform and its inverse, and the second imparting a spatially varying momentum to the Fourier transform of the incident light. Using this concept, we fabricate and test a planar monolithic near-infrared retroreflector composed of two layers of silicon nanoposts, which reflects light along its incident direction with a normal incidence efficiency of 78% and a large half-power field of view of 60°. The metasurface retroreflector demonstrates the potential of cascaded metasurfaces for implementing novel high-performance components, and enables low-power and low-weight passive optical transmitters.

OH PLIF Visualization of the UVa Supersonic Combustion Experiment: Configuration A

NASA Technical Reports Server (NTRS)

Johansen, Craig T.; McRae, Colin D.; Danehy, Paul M.; Gallo, Emanuela; Cantu, Luca Maria Luigi; Magnotti, Gaetano; Cutler, Andrew D.; Rockwell, Robert D.; Goyne, Christopher P.; McDaniel, James C.

2012-01-01

Hydroxyl radical (OH) planar laser-induced fluorescence (PLIF) measurements were performed in the University of Virginia s dual-mode scramjet experiment. The test section was set up in configuration A, which includes a Mach 2 nozzle, combustor, and extender section. Hydrogen fuel was injected through an unswept compression ramp at two different equivalence ratios. Through the translation of the optical system and the use of two separate camera views, the entire optical range of the combustor was accessed. Single-shot, average, and standard deviation images of the OH PLIF signal are presented at several streamwise locations. The results show the development of a highly turbulent flame structure and provide an experimental database to be used for numerical model assessment.

OH PLIF Visualization of the UVa Supersonic Combustion Experiment: Configuration A

NASA Technical Reports Server (NTRS)

Johansen, Craig T.; McRae, Colin D.; Danehy, Paul M.; Gallo, Emanuela C. A.; Cantu, Luca M. L.; Magnotti, Gaetano; Cutler, Andrew D.; Rockwell, Robert D., Jr.; Goyne, Chris P.; McDaniel, James C.

2013-01-01

Hydroxyl radical (OH) planar laser-induced fluorescence (PLIF) measurements were performed in the University of Virginia supersonic combustion experiment. The test section was set up in configuration A, which includes a Mach 2 nozzle, combustor, and extender section. Hydrogen fuel was injected through an unswept compression ramp at two different equivalence ratios. Through the translation of the optical system and the use of two separate camera views, the entire optically accessible range of the combustor was imaged. Single-shot, average, and standard deviation images of the OH PLIF signal are presented at several streamwise locations. The results show the development of a highly turbulent flame structure and provide an experimental database to be used for numerical model assessment.

Improved out-coupling efficiency of organic light emitting diodes fabricated on a TiO2 planarization layer with embedded Si oxide nanostructures

NASA Astrophysics Data System (ADS)

Sung, Young Hoon; Jung, Pil-Hoon; Han, Kyung-Hoon; Kim, Yang Doo; Kim, Jang-Joo; Lee, Heon

2017-10-01

In order to increase the out-coupling efficiency of organic light emitting diodes, conical Si oxide nanostructures were formed on a glass substrate using nanoimprint lithography with hydrogen silsesquioxane. Then, the substrate was planarized with TiO2 nanoparticles. Since TiO2 nanoparticles have a higher refractive index than Si oxide, the surface of substrate is physically flat, but optically undulated in a manner that enables optical scattering and suppression of total internal reflection. Subsequently, OLEDs formed on a substrate with nanostructured Si oxide and a TiO2 planarization layer exhibit a 25% increase in out-coupling efficiency by suppressing total internal reflection.

Planar induction of convergence and extension of the neural plate by the organizer of Xenopus.

PubMed

Keller, R; Shih, J; Sater, A K; Moreno, C

1992-03-01

This paper demonstrates that convergence and extension within the neural plate of Xenopus laevis are regulated by planar inductive interactions with the adjacent Spemann organizer. The companion article (Keller et al.: Developmental Dynamics 193:199-217, 1992) showed that the prospective hindbrain and spinal cord occupy a very short and very wide area just above the Spemann organizer in the early gastrula and that these regions converge and extend greatly during gastrulation and neurulation, using a sequence of radial and mediolateral cell intercalations. In this article, we show that "planar" contact of these regions with the organizer at their vegetal edge until stage 11 is sufficient to induce convergence and extension, after which their convergence and extension become autonomous. Grafts of the organizer in planar contact with uninduced ectodermal tissues induce these ectodermal tissues to converge and extend by a planar inductive signal from the organizer. Labeling of the inducing or responding tissues confirms that only planar interactions occur. Neural convergence and extension are actually hindered in explants deliberately constructed so that vertical interactions occur. These results show unambiguously that the Spemann organizer induces the extraordinary and precocious convergence and extension movements of the Xenopus neural plate by planar interactions acting over short distances.

Analysis and design of planar and non-planar wings for induced drag minimization

NASA Technical Reports Server (NTRS)

Mortara, K.; Straussfogel, Dennis M.; Maughmer, Mark D.

1991-01-01

The goal of the work was to develop and validate computational tools to be used for the design of planar and non-planar wing geometries for minimum induced drag. Because of the iterative nature of the design problem, it is important that, in addition to being sufficiently accurate for the problem at hand, they are reasonably fast and computationally efficient. Toward this end, a method of predicting induced drag in the presence of a non-rigid wake is coupled with a panel method. The induced drag prediction technique is based on the Kutta-Joukowski law applied at the trailing edge. Until recently, the use of this method has not been fully explored and pressure integration and Trefftz-plane calculations favored. As is shown in this report, however, the Kutta-Joukowski method is able to give better results for a given amount of effort than the more common techniques, particularly when relaxed wakes and non-planar wing geometries are considered. Using these tools, a workable design method is in place which takes into account relaxed wakes and non-planar wing geometries. It is recommended that this method be used to design a wind-tunnel experiment to verify the predicted aerodynamic benefits of non-planar wing geometries.

Optical waveguides in magneto-optical glasses fabricated by proton implantation

NASA Astrophysics Data System (ADS)

Liu, Chun-Xiao; Li, Yu-Wen; Zheng, Rui-Lin; Fu, Li-Li; Zhang, Liao-Lin; Guo, Hai-Tao; Zhou, Zhi-Guang; Li, Wei-Nan; Lin, She-Bao; Wei, Wei

2016-11-01

Planar waveguides in magneto-optical glasses (Tb3+-doped aluminum borosilicate glasses) have been produced by a 550-keV proton implantation at a dose of 4.0×1016 ions/cm2 for the first time to our knowledge. After annealing at 260 °C for 1.0 h, the dark-mode spectra and near-field intensity distributions are measured by the prism-coupling and end-face coupling methods. The damage profile, refractive index distribution and light propagation mode of the planar waveguide are numerically calculated by SRIM 2010, RCM and FD-BPM, respectively. The effects of implantation on the structural and optical properties are investigated by Raman and absorption spectra. It suggests that the proton-implanted Tb3+-doped aluminum borosilicate glass waveguide is a good candidate for a waveguide isolator in optical fiber communication and all-optical communication.

Non-Intrusive, Laser-Based Imaging of Jet-A Fuel Injection and Combustion Species in High Pressure, Subsonic Flows

NASA Technical Reports Server (NTRS)

Locke, Randy J.; Hicks, Yolanda R.; Anderson, Robert C.; deGroot, Wilhelmus A.

2001-01-01

The emphasis of combustion research efforts at NASA Glenn Research Center (GRC) is on collaborating with industry to design and test gas-turbine combustors and subcomponents for both sub- and supersonic applications. These next-generation aircraft combustors are required to meet strict international environmental restrictions limiting emissions. To meet these goals, innovative combustor concepts require operation at temperatures and pressures far exceeding those of cur-rent designs. New and innovative diagnostic tools are necessary to characterize these flow streams since existing methods are inadequate. The combustion diagnostics team at GRC has implemented a suite of highly sensitive, nonintrusive optical imaging methods to diagnose the flowfields of these new engine concepts. By using optically accessible combustors and flametubes, imaging of fuel and intermediate combustion species via planar laser-induced fluorescence (PLIF) at realistic pressures are now possible. Direct imaging of the fuel injection process through both planar Mie scattering and PLIF methods is also performed. Additionally, a novel combination of planar fuel fluorescence imaging and computational analysis allows a 3-D examination of the flowfield, resulting in spatially and temporally resolved fuel/air volume distribution maps. These maps provide detailed insight into the fuel injection process at actual conditions, thereby greatly enhancing the evaluation of fuel injector performance and other combustion phenomena. Stable species such as CO2, O2, N2O. and hydrocarbons are also investigated by a newly demonstrated 1-D, spontaneous Raman spectroscopic method. This visible wavelength Raman technique allows the acquisition of quantitative. stable species concentration measurements from the flow.

Non-Intrusive, Laser-Based Imaging of Jet-A Fuel Injection and Combustion Species in High Pressure, Subsonic Flows

NASA Technical Reports Server (NTRS)

Locke, R. J.; Hicks, Y. R.; Anderson, R. C.; deGroot, W. A.

2000-01-01

The emphasis of combustion research efforts at NASA Glenn Research Center (GRC) is on collaborating with industry to design and test gas-turbine combustors and subcomponents for both sub- and supersonic applications. These next-generation aircraft combustors are required to meet strict international environmental restrictions limiting emissions. To meet these goals, innovative combustor concepts require operation at temperatures and pressures far exceeding those of current designs. New and innovative diagnostic tools are necessary to characterize these flow streams since existing methods are inadequate. The combustion diagnostics team at GRC has implemented a suite of highly sensitive, nonintrusive optical imaging methods to diagnose the flowfields of these new engine concepts. By using optically accessible combustors and flame-tubes, imaging of fuel and intermediate combustion species via planar laser-induced fluorescence (PLIF) at realistic pressures are now possible. Direct imaging of the fuel injection process through both planar Mie scattering and PLIF methods is also performed. Additionally, a novel combination of planar fuel fluorescence imaging and computational analysis allows a 3-D examination of the flowfield, resulting in spatially and temporally resolved fuel/air volume distribution maps. These maps provide detailed insight into the fuel injection process at actual conditions, thereby greatly enhancing the evaluation of fuel injector performance and other combustion phenomena. Stable species such as CO2, O2, N2, H2O, and hydrocarbons are also investigated by a newly demonstrated 1-D, spontaneous Raman spectroscopic method. This visible wavelength Raman technique allows the acquisition of quantitative, stable species concentration measurements from the flow.

Ten inch Planar Optic Display

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

Beiser, L.; Veligdan, J.

A Planar Optic Display (POD) is being built and tested for suitability as a high brightness replacement for the cathode ray tube, (CRT). The POD display technology utilizes a laminated optical waveguide structure which allows a projection type of display to be constructed in a thin (I to 2 inch) housing. Inherent in the optical waveguide is a black cladding matrix which gives the display a black appearance leading to very high contrast. A Digital Micromirror Device, (DMD) from Texas Instruments is used to create video images in conjunction with a 100 milliwatt green solid state laser. An anamorphic opticalmore » system is used to inject light into the POD to form a stigmatic image. In addition to the design of the POD screen, we discuss: image formation, image projection, and optical design constraints.« less

Fluorescence particle detection using microfluidics and planar optoelectronic elements

NASA Astrophysics Data System (ADS)

Kettlitz, Siegfried W.; Moosmann, Carola; Valouch, Sebastian; Lemmer, Uli

2014-05-01

Detection of fluorescent particles is an integral part of flow cytometry for analysis of selectively stained cells. Established flow cytometer designs achieve great sensitivity and throughput but require bulky and expensive components which prohibit mass production of small single-use point-of-care devices. The use of a combination of innovative technologies such as roll-to-roll printed microuidics with integrated optoelectronic components such as printed organic light emitting diodes and printed organic photodiodes enables tremendous opportunities in cost reduction, miniaturization and new application areas. In order to harvest these benefits, the optical setup requires a redesign to eliminate the need for lenses, dichroic mirrors and lasers. We investigate the influence of geometric parameters on the performance of a thin planar design which uses a high power LED as planar light source and a PIN-photodiode as planar detector. Due to the lack of focusing optics and inferior optical filters, the device sensitivity is not yet on par with commercial state of the art flow cytometer setups. From noise measurements, electronic and optical considerations we deduce possible pathways of improving the device performance. We identify that the sensitivity is either limited by dark noise for very short apertures or by noise from background light for long apertures. We calculate the corresponding crossover length. For the device design we conclude that a low device thickness, low particle velocity and short aperture length are necessary to obtain optimal sensitivity.

Optoelectronic tweezers for microparticle and cell manipulation

NASA Technical Reports Server (NTRS)

Wu, Ming Chiang (Inventor); Chiou, Pei Yu (Inventor); Ohta, Aaron T. (Inventor)

2009-01-01

An optical image-driven light induced dielectrophoresis (DEP) apparatus and method are described which provide for the manipulation of particles or cells with a diameter on the order of 100 .mu.m or less. The apparatus is referred to as optoelectric tweezers (OET) and provides a number of advantages over conventional optical tweezers, in particular the ability to perform operations in parallel and over a large area without damage to living cells. The OET device generally comprises a planar liquid-filled structure having one or more portions which are photoconductive to convert incoming light to a change in the electric field pattern. The light patterns are dynamically generated to provide a number of manipulation structures that can manipulate single particles and cells or groups of particles/cells. The OET preferably includes a microscopic imaging means to provide feedback for the optical manipulation, such as detecting position and characteristics wherein the light patterns are modulated accordingly.

Optoelectronic Tweezers for Microparticle and Cell Manipulation

NASA Technical Reports Server (NTRS)

Wu, Ming Chiang (Inventor); Chiou, Pei-Yu (Inventor); Ohta, Aaron T. (Inventor)

2014-01-01

An optical image-driven light induced dielectrophoresis (DEP) apparatus and method are described which provide for the manipulation of particles or cells with a diameter on the order of 100 micromillimeters or less. The apparatus is referred to as optoelectric tweezers (OET) and provides a number of advantages over conventional optical tweezers, in particular the ability to perform operations in parallel and over a large area without damage to living cells. The OET device generally comprises a planar liquid-filled structure having one or more portions which are photoconductive to convert incoming light to a change in the electric field pattern. The light patterns are dynamically generated to provide a number of manipulation structures that can manipulate single particles and cells or group of particles/cells. The OET preferably includes a microscopic imaging means to provide feedback for the optical manipulation, such as detecting position and characteristics wherein the light patterns are modulated accordingly.

An ultrawide-bandwidth single-sideband modulator for terahertz frequencies

NASA Astrophysics Data System (ADS)

Meijer, A. S.; Berden, G.; Arslanov, D. D.; Ozerov, M.; Jongma, R. T.; van der Zande, W. J.

2016-11-01

Wireless high-speed data communication using terahertz (THz) carrier frequencies is becoming reality with data rates beyond 100 Gbit s-1. Many of the mobile applications use internet access and require that THz wireless base stations are connected to a global network, such as the radio-over-fibre network. We present the realization of an ultrawide bandwidth THz optical single-sideband (OSSB) modulator for converting (free-space) THz signals to THz optical modulations with an increased spectral efficiency. THz OSSB will mitigate chromatic dispersion-induced propagation losses in optical fibres and support digital modulation schemes. We demonstrate THz OSSB for free-space radiation between 0.3 and 1.0 THz using a specially designed dichroic beamsplitter for signal and carrier, and a planar light-wave circuit with multimode interference structures. This arrangement of optical elements mimics the Hartley single-sideband modulator for electronics signals and accomplishes the required Hilbert transform without any frequency-dependent tuning element over an ultrawide THz spectrum.

Chiral optical response of planar and symmetric nanotrimers enabled by heteromaterial selection

PubMed Central

Banzer, Peter; Woźniak, Paweł; Mick, Uwe; De Leon, Israel; Boyd, Robert W.

2016-01-01

Chirality is an intriguing property of certain molecules, materials or artificial nanostructures, which allows them to interact with the spin angular momentum of the impinging light field. Due to their chiral geometry, they can distinguish between left- and right-hand circular polarization states or convert them into each other. Here we introduce an approach towards optical chirality, which is observed in individual two-dimensional and geometrically mirror-symmetric nanostructures. In this scheme, the chiral optical response is induced by the chosen heterogeneous material composition of a particle assembly and the corresponding resonance behaviour of the constituents it is built from, which breaks the symmetry of the system. As a proof of principle, we investigate such a structure composed of individual silicon and gold nanoparticles both experimentally, as well as numerically. Our proposed concept constitutes an approach for designing two-dimensional chiral media tailored at the nanoscale, allowing for high tunability of their optical response. PMID:27734960

Enantioselective synthesis of allylic esters via asymmetric allylic substitution with metal carboxylates using planar-chiral cyclopentadienyl ruthenium catalysts.

PubMed

Kanbayashi, Naoya; Onitsuka, Kiyotaka

2010-02-03

An asymmetric allylic substitution with sodium carboxylate using a planar-chiral cyclopentadienyl ruthenium complex has been developed. Optically active allylic esters were prepared in good yields with high regio- and enantioselectivities.

Design and simulation of multifunctional optical devices using metasurfaces

NASA Astrophysics Data System (ADS)

Alyammahi, Saleimah

In classical optics, optical components such as lenses and microscopes are unable to focus the light into deep subwavelength or nanometer scales due to the diffraction limit. However, recent developments in nanophotonics, have enabled researchers to control the light at subwavelength scales and overcome the diffraction limit. Using subwavelength structures, we can create a new class of optical materials with unusual optical responses or with new properties that are not attainable in nature. Such artificial materials can be created by structuring conventional materials on the subwavelength scale, giving rise to the unusual optical properties due to the electric and magnetic responses of each meta-atom. These materials are called metamaterials or engineered materials that exhibit exciting phenomena such as non-linear optical responses and negative refraction. Metasurfaces are two dimensional meta-atoms arranged as an array with subwavelength distances. Therefore, metasurfaces are planar, ultrathin version of metamaterials that offer fascinating possibilities of manipulating the wavefront of the optical fields. Recently, the control of light properties such as phase, amplitude, and polarization has been demonstrated by introducing abrupt phase change across a subwavelength scale. Phase discontinuities at the interface can be attained by engineered metasurfaces with new applications and functionalities that have not been realized with bulk or multilayer materials. In this work, high efficient, planar metasurfaces based on geometric phase are designed to realize various functionalities. The designs include metalenses, axicon lenses, vortex beam generators, and Bessel vortex beam generators. The capability of planar metasurfaces in focusing the incident beams and shaping the optical wavefront is numerically demonstrated. COMSOL simulations are used to prove the capability of these metasurfaces to transform the incident beams into complex beams that carry orbital angular momentum (OAM). New designs of ultrathin, planar metasurfaces may result in development of a new type of photonic devices with reduced loss and broad bandwidth. The advances in metasurface designs will lead to ultrathin devices with surprising functionalities and low cost. These novel designs may offer more possibilities for applications in quantum optic devices, pulse shaping, spatial light modulators, nano-scale sensing or imaging, and so on.

Process technologies of MPACVD planar waveguide devices and fiber attachment

NASA Astrophysics Data System (ADS)

Li, Cheng-Chung; Qian, Fan; Boudreau, Robert A.; Rowlette, John R., Sr.; Bowen, Terry P.

1999-03-01

Optical circuits based on low-loss glass waveguide on silicon are a practical and promising approach to integrate different functional components. Fiber attachment to planar waveguide provides a practical application for optical communications. Microwave Plasma Assisted Chemical Vapor Deposition (MPACVD) produces superior quality, low birefringence, low-loss, planar waveguides for integrated optical devices. Microwave plasma initiates the chemical vapor of SiCl4, GeCl4 and oxygen. A Ge-doped silica layer is thus deposited with a compatible high growth rate (i.e. 0.4 - 0.5 micrometer/min). Film properties are based on various parameters, such as chemical flow rates, chamber pressure and temperature, power level and injector design. The resultant refractive index can be varied between 1.46 (i.e. pure silica) and 1.60 (i.e. pure germania). Waveguides can be fabricated with any desired refractive index profile. Standard photolithography defines the waveguide pattern on a mask layer. The core layer is removed by plasma dry etch which has been investigated by both reactive ion etch (RIE) and inductively coupled plasma (ICP) etch. Etch rates of 3000 - 4000 angstrom/min have been achieved using ICP compared to typical etch rates of 200 - 300 angstrom/min using conventional RIE. Planar waveguides offer good mode matching to optical fiber. A polished fiber end can be glued to the end facet of waveguide with a very low optical coupling loss. In addition, anisotropic etching of silicon V- grooves provides a passive alignment capability. Epoxy and solder were used to fix the fiber within the guiding groove. Several designs of waveguide-fiber attachment will be discussed.

Analysis and design of planar and non-planar wings for induced drag minimization

NASA Technical Reports Server (NTRS)

Mortara, Karl W.; Straussfogel, Dennis M.; Maughmer, Mark D.

1992-01-01

The goal of the work reported herein is to develop and validate computational tools to be used for the design of planar and non-planar wing geometries for minimum induced drag. Because of the iterative nature of the design problem, it is important that, in addition to being sufficiently accurate for the problem at hand, these tools need to be reasonably fast and computationally efficient. Toward this end, a method of predicting induced drag in the presence of a free wake has been coupled with a panel method. The induced drag prediction technique is based on the application of the Kutta-Joukowski law at the trailing edge. Until now, the use of this method has not been fully explored and pressure integration and Trefftz-plane calculations favored. As is shown in this report, however, the Kutta-Joukowski method is able to give better results for a given amount of effort than the more commonly used techniques, particularly when relaxed wakes and non-planar wing geometries are considered. Using these methods, it is demonstrated that a reduction in induced drag can be achieved through non-planar wing geometries. It remains to determine what overall drag reductions are possible when the induced drag reduction is traded-off against increased wetted area. With the design methodology that is described herein, such trade studies can be performed in which the non-linear effects of the free wake are taken into account.

Excitation/Detection Strategies for OH Planar Laser-Induced Fluorescence Measurements in the Presence of Interfering Fuel Signal and Absorption Effects

NASA Technical Reports Server (NTRS)

Heath, Christopher M.; Anderson, Robert C.; Hicks, Yolanda R.

2011-01-01

Planar laser-induced fluorescence (PLIF) excitation/detection methods have been applied to obtain spatial distributions of the hydroxyl [OH] reacting intermediary and hydrocarbon [HC] primary species in laminar and turbulent combustion reactions. In this report, broadband and narrowband excitation/filtering techniques are explored to identify an optimal experimental configuration yielding significant fluorescent signal with low absorption losses. The combustion environments analyzed include 1) a laminar non-premixed methane/air flame and 2) a turbulent, non-premixed Jet-A/air fueled flame within a lean flame tube combustor. Hydrocarbon-based fuel and OH were excited via the R1 (1), R1(10) and R2(7) transitions of the A(sup 2)Epsilon(+) X(sup 2)pi(1,0) band using a broadband Nd:YAG pumped optical parametric oscillator (OPO) and narrowband Nd:YAG/dye laser with ultraviolet frequency extension (UVX) package. Variables tested for influence on fluorescent signal and absorption characteristics were excitation line, laser energy, exciting linewidth, combustion reactants, and test flow conditions. Results are intended to guide the transition from a dye/UVX laser to an OPO system for performing advanced diagnostics of low-emission combustion concepts.

Recombination emissions and spectral blueshift of pump radiation from ultrafast laser induced plasma in a planar water microjet

NASA Astrophysics Data System (ADS)

Anija, M.; Philip, Reji

2009-09-01

We report spectroscopic investigations of an ultrafast laser induced plasma generated in a planar water microjet. Plasma recombination emissions along with the spectral blueshift and broadening of the pump laser pulse contribute to the total emission. The laser pulses are of 100 fs duration, and the incident intensity is around 10 15 W/cm 2. The dominant mechanisms leading to plasma formation are optical tunnel ionization and collisional ionization. Spectrally resolved polarization measurements show that the high frequency region of the emission is unpolarized whereas the low frequency region is polarized. Results indicate that at lower input intensities the emission arises mainly from plasma recombinations, which is accompanied by a weak blueshift of the incident laser pulse. At higher input intensities strong recombination emissions are seen, along with a broadening and asymmetric spectral blueshift of the pump laser pulse. From the nature of the blueshifted laser pulse it is possible to deduce whether the rate of change of free electron density is a constant or variable within the pulse lifetime. Two input laser intensity regimes, in which collisional and tunnel ionizations are dominant respectively, have been thus identified.

Nonclassical-light generation in a photonic-band-gap nonlinear planar waveguide

NASA Astrophysics Data System (ADS)

Peřina, Jan, Jr.; Sibilia, Concita; Tricca, Daniela; Bertolotti, Mario

2004-10-01

The optical parametric process occurring in a photonic-band-gap planar waveguide is studied from the point of view of nonclassical-light generation. The nonlinearly interacting optical fields are described by the generalized superposition of coherent signals and noise using the method of operator linear corrections to a classical strong solution. Scattered backward-propagating fields are taken into account. Squeezed light as well as light with sub-Poissonian statistics can be obtained in two-mode fields under the specified conditions.

Theory of absorption integrated optical sensor of gaseous materials

NASA Astrophysics Data System (ADS)

Egorov, A. A.

2010-10-01

The eigen and noneigen (leaky) modes of a three-layer planar integrated optical waveguide are described. The dispersion relation of a three-layer planar waveguide and other dependences are derived, and the cutoff conditions are analyzed. The diagram of propagation constants of the guided and radiation modes of an irregular asymmetric three-layer waveguide and the dependence of the electric field amplitudes of radiation modes of substrate on vertical coordinate in a tantalum integrated optical waveguide are presented. The operating principles of an absorption integrated optical waveguide sensor are investigated. The dependences of sensitivity of an integrated optical waveguide sensor on the sensory cell length, the coupling efficiency of the laser radiation into the waveguide, the absorption cross-section of the studied material, and the level of additive statistical noise are investigated. Some of the prospective areas of application of integrated-optical waveguide sensors are outlined.

Improved Design of Optical MEMS Using the SUMMiT Fabrication Process

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

Michalicek, M.A.; Comtois, J.H.; Barron, C.C.

This paper describes the design and fabrication of optical Microelectromechanical Systems (MEMS) devices using the Sandia Ultra planar Multilevel MEMS Technology (SUMMiT) fabrication process. This state of the art process, offered by Sandia National Laboratories, provides unique and very advantageous features which make it ideal for optical devices. This enabling process permits the development of micromirror devices with near ideal characteristics which have previously been unrealizable in standard polysilicon processes. This paper describes such characteristics as elevated address electrodes, individual address wiring beneath the device, planarized mirror surfaces, unique post-process metallization, and the best active surface area to date.

Optical switch

DOEpatents

Reedy, Robert P.

1987-01-01

An optical switching device (10) is provided whereby light from a first glass fiber (16) or a second glass fiber (14) may be selectively transmitted into a third glass fiber (18). Each glass fiber is provided with a focusing and collimating lens system (26, 28, 30). In one mode of operation, light from the first glass fiber (16) is reflected by a planar mirror (36) into the third glass fiber (18). In another mode of operation, light from the second glass fiber (14) passes directly into the third glass fiber (18). The planar mirror (36) is attached to a rotatable table (32) which is rotated to provide the optical switching.

Creating and optimizing interfaces for electric-field and photon-induced charge transfer.

PubMed

Park, Byoungnam; Whitham, Kevin; Cho, Jiung; Reichmanis, Elsa

2012-11-27

We create and optimize a structurally well-defined electron donor-acceptor planar heterojunction interface in which electric-field and/or photon-induced charge transfer occurs. Electric-field-induced charge transfer in the dark and exciton dissociation at a pentacene/PCBM interface were probed by in situ thickness-dependent threshold voltage shift measurements in field-effect transistor devices during the formation of the interface. Electric-field-induced charge transfer at the interface in the dark is correlated with development of the pentacene accumulation layer close to PCBM, that is, including interface area, and dielectric relaxation time in PCBM. Further, we demonstrate an in situ test structure that allows probing of both exciton diffusion length and charge transport properties, crucial for optimizing optoelectronic devices. Competition between the optical absorption length and the exciton diffusion length in pentacene governs exciton dissociation at the interface. Charge transfer mechanisms in the dark and under illumination are detailed.

Three sets of crystallographic sub-planar structures in quartz formed by tectonic deformation

NASA Astrophysics Data System (ADS)

Derez, Tine; Pennock, Gill; Drury, Martyn; Sintubin, Manuel

2016-05-01

In quartz, multiple sets of fine planar deformation microstructures that have specific crystallographic orientations parallel to planes with low Miller-Bravais indices are commonly considered as shock-induced planar deformation features (PDFs) diagnostic of shock metamorphism. Using polarized light microscopy, we demonstrate that up to three sets of tectonically induced sub-planar fine extinction bands (FEBs), sub-parallel to the basal, γ, ω, and π crystallographic planes, are common in vein quartz in low-grade tectonometamorphic settings. We conclude that the observation of multiple (2-3) sets of fine scale, closely spaced, crystallographically controlled, sub-planar microstructures is not sufficient to unambiguously distinguish PDFs from tectonic FEBs.

Thick optical waveguides in lithium niobate induced by swift heavy ions (approximately 10 MeV/amu) at ultralow fluences.

PubMed

Olivares, José; Crespillo, Miguel L; Caballero-Calero, Olga; Ynsa, María D; García-Cabañes, Angel; Toulemonde, Marcel; Trautmann, Christina; Agulló-López, Fernando

2009-12-21

Heavy mass ions, Kr and Xe, having energies in the approximately 10 MeV/amu range have been used to produce thick planar optical waveguides at the surface of lithium niobate (LiNbO3). The waveguides have a thickness of 40-50 micrometers, depending on ion energy and fluence, smooth profiles and refractive index jumps up to 0.04 (lambda = 633 nm). They propagate ordinary and extraordinary modes with low losses keeping a high nonlinear optical response (SHG) that makes them useful for many applications. Complementary RBS/C data provide consistent values for the partial amorphization and refractive index change at the surface. The proposed method is based on ion-induced damage caused by electronic excitation and essentially differs from the usual implantation technique using light ions (H and He) of MeV energies. It implies the generation of a buried low-index layer (acting as optical barrier), made up of amorphous nanotracks embedded into the crystalline lithium niobate crystal. An effective dielectric medium approach is developed to describe the index profiles of the waveguides. This first test demonstration could be extended to other crystalline materials and could be of great usefulness for mid-infrared applications.

Three-dimensional crossbar interconnection using planar-integrated free-space optics and digital mirror-device

NASA Astrophysics Data System (ADS)

Lohmann, U.; Jahns, J.; Limmer, S.; Fey, D.

2011-01-01

We consider the implementation of a dynamic crossbar interconnect using planar-integrated free-space optics (PIFSO) and a digital mirror-device™ (DMD). Because of the 3D nature of free-space optics, this approach is able to solve geometrical problems with crossings of the signal paths that occur in waveguide optical and electrical interconnection, especially for large number of connections. The DMD device allows one to route the signals dynamically. Due to the large number of individual mirror elements in the DMD, different optical path configurations are possible, thus offering the chance for optimizing the network configuration. The optimization is achieved by using an evolutionary algorithm for finding best values for a skewless parallel interconnection. Here, we present results and experimental examples for the use of the PIFSO/DMD-setup.

Measurement of ultrafast optical Kerr effect of Ge-Sb-Se chalcogenide slab waveguides by the beam self-trapping technique

NASA Astrophysics Data System (ADS)

Kuriakose, Tintu; Baudet, Emeline; Halenkovič, Tomáš; Elsawy, Mahmoud M. R.; Němec, Petr; Nazabal, Virginie; Renversez, Gilles; Chauvet, Mathieu

2017-11-01

We present a reliable and original experimental technique based on the analysis of beam self-trapping to measure ultrafast optical nonlinearities in planar waveguides. The technique is applied to the characterization of Ge-Sb-Se chalcogenide films that allow Kerr induced self-focusing and soliton formation. Linear and nonlinear optical constants of three different chalcogenide waveguides are studied at 1200 and 1550 nm in femtosecond regime. Waveguide propagation loss and two photon absorption coefficients are determined by transmission analysis. Beam broadening and narrowing results are compared with simulations of the nonlinear Schrödinger equation solved by BPM method to deduce the Kerr n2 coefficients. Kerr optical nonlinearities obtained by our original technique compare favorably with the values obtained by Z-scan technique. Nonlinear refractive index as high as (69 ± 11) × 10-18m2 / W is measured in Ge12.5Sb25Se62.5 at 1200 nm with low nonlinear absorption and low propagation losses which reveals the great characteristics of our waveguides for ultrafast all optical switching and integrated photonic devices.

Two-phase SLIPI for instantaneous LIF and Mie imaging of transient fuel sprays.

PubMed

Storch, Michael; Mishra, Yogeshwar Nath; Koegl, Matthias; Kristensson, Elias; Will, Stefan; Zigan, Lars; Berrocal, Edouard

2016-12-01

We report in this Letter a two-phase structured laser illumination planar imaging [two-pulse SLIPI (2p-SLIPI)] optical setup where the "lines structure" is spatially shifted by exploiting the birefringence property of a calcite crystal. By using this optical component and two cross-polarized laser pulses, the shift of the modulated pattern is not "time-limited" anymore. Consequently, two sub-images with spatially mismatched phases can be recorded within a few hundred of nanoseconds only, freezing the motion of the illuminated transient flow. In comparison with previous setups for instantaneous imaging based on structured illumination, the current optical design presents the advantage of having a single optical path, greatly simplifying its complexity. Due to its virtue of suppressing the effects from multiple light scattering, the 2p-SLIPI technique is applied here in an optically dense multi-jet direct-injection spark-ignition (DISI) ethanol spray. The fast formation of polydispersed droplets and appearance of voids after fuel injection are investigated by simultaneous detection of Mie scattering and liquid laser-induced fluorescence. The results allow for significantly improved analysis of the spray structure.

Experimental investigation on aero-optics of supersonic turbulent boundary layers.

PubMed

Ding, Haolin; Yi, Shihe; Zhu, Yangzhu; He, Lin

2017-09-20

Nanoparticle-based planar laser scattering was used to measure the density distribution of the supersonic (Ma=3.0) turbulent boundary layer and the optical path difference (OPD), which is quite crucial for aero-optics study. Results were obtained using ray tracing. The influences of different layers in the boundary layer, turbulence scales, and light incident angle on aero-optics were examined, and the underlying flow physics were analyzed. The inner layer plays a dominant role, followed by the outer layer. One hundred OPD rms of the outer layer at different times satisfy the normal distribution better than that of the inner layer. Aero-optics induced by the outer layer is sensitive to the filter scale. When induced by the inner layer, it is not sensitive to the filter scale. The vortices with scales less than the Kolmogorov scale (=46.0  μm) have little influence on the aero-optics and could be ignored; the validity of the smallest optically active scale (=88.1  μm) proposed by Mani is verified, and vortices with scales less than that are ignored, resulting in a 1.62% decay of aero-optics; the filter with a width of 16-grid spacing (=182.4  μm) decreases OPD rms by 7.04%. With the increase of the angle between the wall-normal direction and the light-incident direction, the aero-optics becomes more serious, and the difference between the distribution of the OPD rms and the normal distribution increases. The difficulty of aero-optics correction is increased. Light tilted toward downstream experiences more distortions than when tilted toward upstream at the same angle relative to the wall-normal direction.

Role of molecular conformations in rubrene polycrystalline films growth from vacuum deposition at various substrate temperatures

NASA Astrophysics Data System (ADS)

Lin, Ku-Yen; Wang, Yan-Jun; Chen, Ko-Lun; Ho, Ching-Yuan; Yang, Chun-Chuen; Shen, Ji-Lin; Chiu, Kuan-Cheng

2017-01-01

We report on the optical and structural characterization of rubrene polycrystalline films fabricated from vacuum deposition with various substrate temperatures (Tsub). Depending on Tsub, the role of twisted and planar rubrene conformational isomers on the properties of rubrene films is focused. The temperature (T)-dependent inverse optical transmission (IOT) and photoluminescence (PL) spectra were performed on these rubrene films. The origins of these IOT and PL peaks are explained in terms of the features from twisted and planar rubrene molecules and of the band characteristics from rubrene molecular solid films. Here, two rarely reported weak-peaks at 2.431 and 2.605 eV were observed from IOT spectra, which are associated with planar rubrene. Besides, the T-dependence of optical bandgap deduced from IOT spectra is discussed with respect to Tsub. Together with IOT and PL spectra, for Tsub > 170 °C, the changes in surface morphology and unit cell volume were observed for the first time, and are attributed to the isomeric transformation from twisted to planar rubrenes during the deposition processes. Furthermore, a unified schematic diagram in terms of Frenkel exciton recombination is suggested to explain the origins of the dominant PL peaks performed on these rubrene films at 15 K.

Emission Characteristics of Organic Light-Emitting Diodes and Organic Thin-Films with Planar and Corrugated Structures

PubMed Central

Wei, Mao-Kuo; Lin, Chii-Wann; Yang, Chih-Chung; Kiang, Yean-Woei; Lee, Jiun-Haw; Lin, Hoang-Yan

2010-01-01

In this paper, we review the emission characteristics from organic light-emitting diodes (OLEDs) and organic molecular thin films with planar and corrugated structures. In a planar thin film structure, light emission from OLEDs was strongly influenced by the interference effect. With suitable design of microcavity structure and layer thicknesses adjustment, optical characteristics can be engineered to achieve high optical intensity, suitable emission wavelength, and broad viewing angles. To increase the extraction efficiency from OLEDs and organic thin-films, corrugated structure with micro- and nano-scale were applied. Microstructures can effectively redirects the waveguiding light in the substrate outside the device. For nanostructures, it is also possible to couple out the organic and plasmonic modes, not only the substrate mode. PMID:20480033

Defect-induced infrared electroluminescence from radial GaInP/AlGaInP quantum well nanowire array light- emitting diodes

NASA Astrophysics Data System (ADS)

Hussain, Laiq; Karimi, Mohammad; Berg, Alexander; Jain, Vishal; Borgström, Magnus T.; Gustafsson, Anders; Samuelson, Lars; Pettersson, Håkan

2017-12-01

Radial GaInP/AlGaInP nanowire array light-emitting diodes (LEDs) are promising candidates for novel high-efficiency solid state lighting due to their potentially large strain-free active emission volumes compared to planar LEDs. Moreover, by proper tuning of the diameter of the nanowires, the fraction of emitted light extracted can be significantly enhanced compared to that of planar LEDs. Reports so far on radial growth of nanowire LED structures, however, still point to significant challenges related to obtaining defect-free radial heterostructures. In this work, we present evidence of optically active growth-induced defects in a fairly broad energy range in vertically processed radial GaInP/AlGaInP quantum well nanowire array LEDs using a variety of complementary experimental techniques. In particular, we demonstrate strong infrared electroluminescence in a spectral range centred around 1 eV (1.2 μm) in addition to the expected red light emission from the quantum well. Spatially resolved cathodoluminescence studies reveal a patchy red light emission with clear spectral features along the NWs, most likely induced by variations in QW thickness, composition and barriers. Dark areas are attributed to infrared emission generated by competing defect-assisted radiative transitions, or to trapping mechanisms involving non-radiative recombination processes. Possible origins of the defects are discussed.

Spatial inhomogeneities in Al x Ga1-x N quantum wells induced by the surface morphology of AlN/sapphire templates

NASA Astrophysics Data System (ADS)

Zeimer, Ute; Jeschke, Joerg; Mogilatenko, Anna; Knauer, Arne; Kueller, Viola; Hoffmann, Veit; Kuhn, Christian; Simoneit, Tino; Martens, Martin; Wernicke, Tim; Kneissl, Michael; Weyers, Markus

2015-11-01

The effects of the template on the optical and structural properties of Al0.75Ga0.25N/Al0.8Ga0.2N multiple quantum well (MQWs) laser active regions have been investigated. The laser structures for optical pumping were grown on planar c-plane AlN/sapphire as well as on thick epitaxially laterally overgrown (ELO) AlN layers on patterned AlN/sapphire. Two ELO AlN/sapphire templates were investigated, one with a miscut of the sapphire surface to the m-direction with an angle of 0.25°, the other with a miscut angle of 0.25° to the sapphire a-direction. The MQWs are studied by atomic force microscopy, plan-view cathodoluminescence (CL) at room temperature and 83 K as well as transmission electron microscopy using high-angle annular dark-field imaging and energy-dispersive x-ray spectroscopy. The results are compared to optical pumping measurements. It was found that the surface morphology of the templates determines the lateral wavelength distribution in the MQWs observed by spectral CL mappings. The lateral wavelength spread is largest for the laser structures grown on ELO AlN with miscut to sapphire a-direction caused by the local variation of the MQW thicknesses and the Ga incorporation at macrosteps on the ELO-AlN. A CL peak wavelength spread of up to 7 nm has been found. The MQWs grown on planar AlN/sapphire templates show a homogeneous wavelength distribution. However, due to the high threading dislocation density and the resulting strong nonradiative recombination, laser operation could not be achieved. The laser structures grown on ELO AlN/sapphire show optically pumped lasing with a record short wavelength of 237 nm.

Thin glass based packaging and photonic single-mode waveguide integration by ion-exchange technology on board and module level

NASA Astrophysics Data System (ADS)

Brusberg, Lars; Lang, Günter; Schröder, Henning

2011-01-01

The proposed novel packaging approach merges micro-system packaging and glass integrated optics. It provides 3D optical single-mode intra system links to bridge the gap between novel photonic integrated circuits and the glass fibers for inter system interconnects. We introduce our hybrid 3D photonic packaging approach based on thin glass substrates with planar integrated optical single-mode waveguides for fiber-to-chip and chip-to-chip links. Optical mirrors and lenses provide optical mode matching for photonic IC assemblies and optical fiber interconnects. Thin glass is commercially available in panel and wafer formats and characterizes excellent optical and high-frequency properties as reviewed in the paper. That makes it perfect for micro-system packaging. The adopted planar waveguide process based on ion-exchange technology is capable for high-volume manufacturing. This ion-exchange process and the optical propagation are described in detail for thin glass substrates. An extensive characterization of all basic circuit elements like straight and curved waveguides, couplers and crosses proves the low attenuation of the optical circuit elements.

A chip-integrated coherent photonic-phononic memory.

PubMed

Merklein, Moritz; Stiller, Birgit; Vu, Khu; Madden, Stephen J; Eggleton, Benjamin J

2017-09-18

Controlling and manipulating quanta of coherent acoustic vibrations-phonons-in integrated circuits has recently drawn a lot of attention, since phonons can function as unique links between radiofrequency and optical signals, allow access to quantum regimes and offer advanced signal processing capabilities. Recent approaches based on optomechanical resonators have achieved impressive quality factors allowing for storage of optical signals. However, so far these techniques have been limited in bandwidth and are incompatible with multi-wavelength operation. In this work, we experimentally demonstrate a coherent buffer in an integrated planar optical waveguide by transferring the optical information coherently to an acoustic hypersound wave. Optical information is extracted using the reverse process. These hypersound phonons have similar wavelengths as the optical photons but travel at five orders of magnitude lower velocity. We demonstrate the storage of phase and amplitude of optical information with gigahertz bandwidth and show operation at separate wavelengths with negligible cross-talk.Optical storage implementations based on optomechanical resonator are limited to one wavelength. Here, exploiting stimulated Brillouin scattering, the authors demonstrate a coherent optical memory based on a planar integrated waveguide, which can operate at different wavelengths without cross-talk.

Free space and waveguide Talbot effect: phase relations and planar light circuit applications

NASA Astrophysics Data System (ADS)

Nikkhah, H.; Zheng, Q.; Hasan, I.; Abdul-Majid, S.; Hall, T. J.

2012-10-01

Optical fields that are periodic in the transverse plane self-image periodically as they propagate along the optical axis: a phenomenon known as the Talbot effect. A transfer matrix may be defined that relates the amplitude and phase of point sources placed on a particular grid at the input to their respective multiple images at an image plane. The free-space Talbot effect may be mapped to the waveguide Talbot effect. Applying this mapping to the transfer matrix enables the prediction of the phase and amplitude relations between the ports of a Multimode Interference (MMI) coupler- a planar waveguide device. The transfer matrix approach has not previously been applied to the free-space case and its mapping to the waveguide case provides greater clarity and physical insight into the phase relationships than previous treatments. The paper first introduces the underlying physics of the Talbot effect in free space with emphasis on the positions along the optical axis at which images occur; their multiplicity; and their relative phase relations determined by the Gauss Quadratic Sum of number theory. The analysis is then adapted to predict the phase relationships between the ports of an MMI. These phase relationships are critical to planar light circuit (PLC) applications such as 90° optical hybrids for coherent optical receiver front-ends, external optical I-Q modulators for coherent optical transmitters; and optical phased array switches. These applications are illustrated by results obtained from devices that have been fabricated and tested by the PTLab in Si micro-photonic integration platforms.

Optical gain measurements in porous silicon planar waveguides codoped by erbium and ytterbium ions at 1.53 μm

NASA Astrophysics Data System (ADS)

Najar, Adel; Charrier, Joël; Lorrain, Nathalie; Haji, Lazhar; Oueslati, Mehrezi

2007-09-01

The on-off optical gain measurements as a function of the pump power were performed on porous silicon planar waveguides codoped by erbium and ytterbium ions. These measurements were obtained for different ratios of Yb concentration to Er concentration. The highest value of the gain was reached when the Yb concentration is three times higher than that of Er at a moderate 980nm pump power value equal to 70mW. Optical losses measurements have been performed on these waveguides and were equal to 2.1dB/cm and an internal gain of about 6.4dB/cm was obtained.

Peptide Integrated Optics.

PubMed

Handelman, Amir; Lapshina, Nadezda; Apter, Boris; Rosenman, Gil

2018-02-01

Bio-nanophotonics is a wide field in which advanced optical materials, biomedicine, fundamental optics, and nanotechnology are combined and result in the development of biomedical optical chips. Silk fibers or synthetic bioabsorbable polymers are the main light-guiding components. In this work, an advanced concept of integrated bio-optics is proposed, which is based on bioinspired peptide optical materials exhibiting wide optical transparency, nonlinear and electrooptical properties, and effective passive and active waveguiding. Developed new technology combining bottom-up controlled deposition of peptide planar wafers of a large area and top-down focus ion beam lithography provides direct fabrication of peptide optical integrated circuits. Finding a deep modification of peptide optical properties by reconformation of biological secondary structure from native phase to β-sheet architecture is followed by the appearance of visible fluorescence and unexpected transition from a native passive optical waveguiding to an active one. Original biocompatibility, switchable regimes of waveguiding, and multifunctional nonlinear optical properties make these new peptide planar optical materials attractive for application in emerging technology of lab-on-biochips, combining biomedical photonic and electronic circuits toward medical diagnosis, light-activated therapy, and health monitoring. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Polymer waveguide grating sensor integrated with a thin-film photodetector

PubMed Central

Song, Fuchuan; Xiao, Jing; Xie, Antonio Jou; Seo, Sang-Woo

2014-01-01

This paper presents a planar waveguide grating sensor integrated with a photodetector (PD) for on-chip optical sensing systems which are suitable for diagnostics in the field and in-situ measurements. III–V semiconductor-based thin-film PD is integrated with a polymer based waveguide grating device on a silicon platform. The fabricated optical sensor successfully discriminates optical spectral characteristics of the polymer waveguide grating from the on-chip PD. In addition, its potential use as a refractive index sensor is demonstrated. Based on a planar waveguide structure, the demonstrated sensor chip may incorporate multiple grating waveguide sensing regions with their own optical detection PDs. In addition, the demonstrated processing is based on a post-integration process which is compatible with silicon complementary metal-oxide semiconductor (CMOS) electronics. Potentially, this leads a compact, chip-scale optical sensing system which can monitor multiple physical parameters simultaneously without need for external signal processing. PMID:24466407

Fabrication of planar optical waveguides by 6.0 MeV silicon ion implantation in Nd-doped phosphate glasses

NASA Astrophysics Data System (ADS)

Shen, Xiao-Liang; Dai, Han-Qing; Zhang, Liao-Lin; Wang, Yue; Zhu, Qi-Feng; Guo, Hai-Tao; Li, Wei-Nan; Liu, Chun-Xiao

2018-04-01

We report the fabrication of a planar optical waveguide by silicon ion implantation into Nd-doped phosphate glass at an energy of 6.0 MeV and a dose of 5.0 × 1014 ions/cm2. The change in the surface morphology of the glass after the implantation can be clearly observed by scanning electron microscopy. The measurement of the dark mode spectrum of the waveguide is conducted using a prism coupler at 632.8 nm. The refractive index distribution of the waveguide is reconstructed by the reflectivity calculation method. The near-field optical intensity profile of the waveguide is measured using an end-face coupling system. The waveguide with good optical properties on the glass matrix may be valuable for the application of the Nd-doped phosphate glass in integrated optical devices.

Two-Dimensional Imaging of OH in a Lean Burning High Pressure Combustor

NASA Technical Reports Server (NTRS)

Locke, R. J.; Hicks, Y. R.; Anderson, R. C.; Ockunzzi, K. A.; North, G. L.

1995-01-01

Planar laser-induced fluorescence (PLIF) images of OH have been obtained from an optically accessible, lean burning high pressure combustor burning Jet-A fuel. These images were obtained using various laser excitation lines of the OH A (reverse arrow) X (1,0) band for several fuel injector configurations with pressures ranging from 1013 kPa (10 atm) to 1419 kPa (14 atm). Non-uniformities in the combusting flow, attributed to differences in fuel injector configuration, are revealed by these images. Contributions attributable to fluorescent aromatic hydrocarbons and complex fuel chemistries are also not evident.

Lithographically-Scribed Planar Holographic Optical CDMA Devices and Systems

DTIC Science & Technology

2007-02-15

operate with quite high refractive index contrast (order 0.5). Thin -filn filter devices are viewed as relatively low in chromatic dispersion. We have...stack consists of planar interfaces between materials of refractive index n, and n,. Let An = In2 - nil and n = (n, - n1)/2. The planar interfaces are... index ). It may be desirable to have a relatively large refractive index differential when diffractive elements are formed from cladding material at a

Hybrid sol-gel planar optics for astronomy.

PubMed

Ghasempour, A; Leite, A M P; Reynaud, F; Marques, P V S; Garcia, P J V; Alexandre, D; Moreira, P J

2009-02-02

Hybrid sol-gel planar optics devices for astronomy are produced for the first time. This material system can operate from the visible (0.5 microm) up to the edge of astronomical J-band (1.4 microm). The design, fabrication and characterization results of a coaxial three beam combiner are given as an example. Fringe contrasts above 94% are obtained with a source with spectral bandwidth of 50 nm. These results demonstrate that hybrid sol-gel technology can produce devices with high quality, opening the possibility of rapid prototyping of new designs and concepts for astronomical applications.

Er 3+ Doping conditions of planar porous silicon waveguides

NASA Astrophysics Data System (ADS)

Najar, A.; Lorrain, N.; Ajlani, H.; Charrier, J.; Oueslati, M.; Haji, L.

2009-11-01

EDX and infrared photoluminescence (IR PL) analyses performed on erbium-doped porous silicon waveguides (PSWG) were studied using different doping conditions. Both parameters of the cathodisation electrochemical method used for Er incorporation and parameters of thermal treatments required for Er optical activation were taken into consideration. Firstly, by varying the current density and the time of cathodisation, we have shown that a current density of 0.1 mA/cm 2 for 10 min allows homogeneous Er doping to be achieved throughout the depth of the guiding layer. Then, the PL intensity at 1.53 μm was studied as a function of the oxidation time at 900 °C and Er diffusion temperature for 60 min. Increasing the oxidation time up to 1 h allows PL to be enhanced due to active Si-O-Er complex formation whereas an oxidation time of 2 h induces a decrease in PL because of Er segregation. Moreover, an increase in the diffusion temperature induces an optimal distribution of optically active Si-Er-O complexes inside the crystallites. When the temperature is too high, a PSWG densification and Er segregation occurs inducing a decrease in PL due to energy transfer phenomena.

A microdisplay-based HUD for automotive applications: Backplane design, planarization, and optical implementation

NASA Astrophysics Data System (ADS)

Schuck, Miller Harry

Automotive head-up displays require compact, bright, and inexpensive imaging systems. In this thesis, a compact head-up display (HUD) utilizing liquid-crystal-on-silicon microdisplay technology is presented from concept to implementation. The thesis comprises three primary areas of HUD research: the specification, design and implementation of a compact HUD optical system, the development of a wafer planarization process to enhance reflective device brightness and light immunity and the design, fabrication and testing of an inexpensive 640 x 512 pixel active matrix backplane intended to meet the HUD requirements. The thesis addresses the HUD problem at three levels, the systems level, the device level, and the materials level. At the systems level, the optical design of an automotive HUD must meet several competing requirements, including high image brightness, compact packaging, video-rate performance, and low cost. An optical system design which meets the competing requirements has been developed utilizing a fully-reconfigurable reflective microdisplay. The design consists of two optical stages, the first a projector stage which magnifies the display, and a second stage which forms the virtual image eventually seen by the driver. A key component of the optical system is a diffraction grating/field lens which forms a large viewing eyebox while reducing the optical system complexity. Image quality biocular disparity and luminous efficacy were analyzed and results of the optical implementation are presented. At the device level, the automotive HUD requires a reconfigurable, video-rate, high resolution image source for applications such as navigation and night vision. The design of a 640 x 512 pixel active matrix backplane which meets the requirements of the HUD is described. The backplane was designed to produce digital field sequential color images at video rates utilizing fast switching liquid crystal as the modulation layer. The design methodology is discussed, and the example of a clock generator is described from design to implementation. Electrical and optical test results of the fabricated backplane are presented. At the materials level, a planarization method was developed to meet the stringent brightness requirements of automotive HUD's. The research efforts described here have resulted in a simple, low cost post-processing method for planarizing microdisplay substrates based on a spin-cast polymeric resin, benzocyclobutene (BCB). Six- fold reductions in substrate step height were accomplished with a single coating. Via masking and dry etching methods were developed. High reflectivity metal was deposited and patterned over the planarized substrate to produce high aperture pixel mirrors. The process is simple, rapid, and results in microdisplays better able to meet the stringent requirements of high brightness display systems. Methods and results of the post- processing are described.

Laser-induced incandescence calibration via gravimetric sampling

NASA Technical Reports Server (NTRS)

Choi, M. Y.; Vander Wal, R. L.; Zhou, Z.

1996-01-01

Absolute calibration of laser-induced incandescence (LII) is demonstrated via comparison of LII signal intensities with gravimetrically determined soot volume fractions. This calibration technique does not rely upon calculated or measured optical characteristics of soot. The variation of the LII signal with gravimetrically measured soot volume fractions ranging from 0.078 to 1.1 ppm established the linearly of the calibration. With the high spatial and temporal resolution capabilities of laser-induced incandescence (LII), the spatial and temporal fluctuations of the soot field within a gravimetric chimney were characterized. Radial uniformity of the soot volume fraction, f(sub v) was demonstrated with sufficient averaging of the single laser-shot LII images of the soot field thus confirming the validity of the calibration method for imaging applications. As illustration, instantaneous soot volume fractions within a Re = 5000 ethylene/air diffusion flame measured via planar LII were established quantitatively with this calibration.

Planar Poincare chart - A planar graphic representation of the state of light polarization

NASA Technical Reports Server (NTRS)

Tedjojuwono, Ken K.; Hunter, William W., Jr.; Ocheltree, Stewart L.

1989-01-01

The planar Poincare chart, which represents the complete planar equivalence of the Poincare sphere, is proposed. The four sets of basic lines are drawn on two separate charts for the generalization and convenience of reading the scale. The chart indicates the rotation of the principal axes of linear birefringent material. The relationships between parameters of the two charts are given as 2xi-2phi (orientation angle of the major axis-ellipticity angle) pair and 2alpha-delta (angle of amplitude ratio-phase difference angle) pair. The results are useful for designing and analyzing polarization properties of optical components with birefringent properties.

Topological photonics: an observation of Landau levels for optical photons

NASA Astrophysics Data System (ADS)

Schine, Nathan; Ryou, Albert; Sommer, Ariel; Simon, Jonathan

We present the first experimental realization of a bulk magnetic field for optical photons. By using a non-planar ring resonator, we induce an image rotation on each round trip through the resonator. This results in a Coriolis/Lorentz force and a centrifugal anticonfining force, the latter of which is cancelled by mirror curvature. Using a digital micromirror device to control both amplitude and phase, we inject arbitrary optical modes into our resonator. Spatial- and energy- resolved spectroscopy tracks photonic eigenstates as residual trapping is reduced, and we observe photonic Landau levels as the eigenstates become degenerate. We show that there is a conical geometry of the resulting manifold for photon dynamics and present a measurement of the local density of states that is consistent with Landau levels on a cone. While our work already demonstrates an integer quantum Hall material composed of photons, we have ensured compatibility with strong photon-photon interactions, which will allow quantum optical studies of entanglement and correlation in manybody systems including fractional quantum Hall fluids. This work was supported by DOE, DARPA, and AFOSR.

Experimental investigation of a supersonic swept ramp injector using laser-induced iodine fluorescence

NASA Technical Reports Server (NTRS)

Hartfield, Roy J.; Hollo, Steven D.; Mcdaniel, James C.

1990-01-01

Planar measurements of injectant mole fraction and temperature have been conducted in a nonreacting supersonic combustor configured with underexpanded injection in the base of a swept ramp. The temperature measurements were conducted with a Mach 2 test section inlet in streamwise planes perpendicular to the test section wall on which the ramp was mounted. Injection concentration measurements, conducted in cross flow planes with both Mach 2 and Mach 2.9 free stream conditions, dramatically illustrate the domination of the mixing process by streamwise vorticity generated by the ramp. These measurements, conducted using a nonintrusive optical technique (laser-induced iodine fluorescence), provide an accurate and extensive experimental data base for the validation of computation fluid dynamic codes for the calculation of highly three-dimensional supersonic combustor flow fields.

Numerical studies on a plasmonic temperature nanosensor based on a metal-insulator-metal ring resonator structure for optical integrated circuit applications

NASA Astrophysics Data System (ADS)

Al-mahmod, Md. Jubayer; Hyder, Rakib; Islam, Md Zahurul

2017-07-01

A nanosensor, based on a metal-insulator-metal (MIM) plasmonic ring resonator, is proposed for potential on-chip temperature sensing and its performance is evaluated numerically. The sensor components can be fabricated by using planar processes on a silicon substrate, making its manufacturing compatible to planar electronic fabrication technology. The sensor, constructed using silver as the metal rings and a thermo-optic liquid ethanol film between the metal layers, is capable of sensing temperature with outstanding optical sensitivity, as high as -0.53 nm/°C. The resonance wavelength is found to be highly sensitive to the refractive index of the liquid dielectric film. The resonance peak can be tuned according to the requirement of intended application by changing the radii of the ring resonator geometries in the design phase. The compact size, planar and silicon-based design, and very high resolutions- these characteristics are expected to make this sensor technology a preferred choice for lab-on-a-chip applications, as compared to other contemporary sensors.

Photonic Landau levels on cones

NASA Astrophysics Data System (ADS)

Schine, Nathan; Ryou, Albert; Gromov, Andrey; Sommer, Ariel; Simon, Jonathan

2016-05-01

We present the first experimental realization of a bulk magnetic field for optical photons. By using a non-planar ring resonator, we induce an image rotation on each round trip through the resonator. This results in a Coriolis/Lorentz force and a centrifugal anticonfining force, the latter of which is cancelled by mirror curvature. Using a digital micromirror device to control both amplitude and phase, we inject arbitrary optical modes into our resonator. Spatial- and energy- resolved spectroscopy tracks photonic eigenstates as residual trapping is reduced, and we observe photonic Landau levels as the eigenstates become degenerate. We show that there is a conical geometry of the resulting manifold for photon dynamics and present a measurement of the local density of states that is consistent with Landau levels on a cone. While our work already demonstrates an integer quantum Hall material composed of photons, we have ensured compatibility with strong photon-photon interactions, which will allow quantum optical studies of entanglement and correlation in manybody systems including fractional quantum Hall fluids.

Geometrical connection between catacaustics and kinematics of planar motion of a rigid solid.

PubMed

Bellver-Cebreros, Consuelo; Rodríguez-Danta, Marcelo

2016-09-01

Unnoticed and hidden optomechanical analogies between kinematics of planar motion of a rigid solid and catacaustics generated by mirror reflection on smooth profiles in geometrical optics are discussed. A concise and self-consistent theory is developed, which intends to explain and clarify many partial aspects covered by the literature.

Planar concentrators at the étendue limit

NASA Astrophysics Data System (ADS)

Winston, Roland; Gordon, Jeffrey M.

2005-08-01

Recently proposed aplanatic imaging designs are integrally combined with nonimaging flux boosters to produce an ultra-compact planar dielectric-filled concentrator that performs near the étendue limit. Such optical devices are attractive for high-efficiency multi-junction photovoltaics at high flux, with realistic power generation of 1 W from a 1 mm2 cell.

A unified planar measurement technique for compressible flows using laser-induced iodine fluorescence

NASA Technical Reports Server (NTRS)

Hartfield, Roy J., Jr.; Hollo, Steven D.; Mcdaniel, James C.

1992-01-01

A unified laser-induced fluorescence technique for conducting planar measurements of temperature, pressure and velocity in nonreacting, highly compressible flows has been developed, validated and demonstrated. Planar fluorescence from iodine, seeded into air, was induced by an argon-ion laser and collected using a liquid-nitrogen cooled CCD camera. In the measurement technique, temperature is determined from the fluorescence induced with the laser operated broad band. Pressure and velocity are determined from the shape and position of the fluorescence excitation spectrum which is measured with the laser operated narrow band. The measurement approach described herein provides a means of obtaining accurate, spatially-complete maps of the primary flow field parameters in a wide variety of cold supersonic and transonic flows.

Planned development of a 3D computer based on free-space optical interconnects

NASA Astrophysics Data System (ADS)

Neff, John A.; Guarino, David R.

1994-05-01

Free-space optical interconnection has the potential to provide upwards of a million data channels between planes of electronic circuits. This may result in the planar board and backplane structures of today giving away to 3-D stacks of wafers or multi-chip modules interconnected via channels running perpendicular to the processor planes, thereby eliminating much of the packaging overhead. Three-dimensional packaging is very appealing for tightly coupled fine-grained parallel computing where the need for massive numbers of interconnections is severely taxing the capabilities of the planar structures. This paper describes a coordinated effort by four research organizations to demonstrate an operational fine-grained parallel computer that achieves global connectivity through the use of free space optical interconnects.

Geometrically induced surface polaritons in planar nanostructured metallic cavities

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

Davids, P. S.; Intravia, F; Dalvit, Diego A.

2014-01-14

We examine the modal structure and dispersion of periodically nanostructured planar metallic cavities within the scattering matrix formulation. By nanostructuring a metallic grating in a planar cavity, artificial surface excitations or spoof plasmon modes are induced with dispersion determined by the periodicity and geometric characteristics of the grating. These spoof surface plasmon modes are shown to give rise to new cavity polaritonic modes at short mirror separations that modify the density of modes in nanostructured cavities. The increased modal density of states form cavity polarirons have a large impact on the fluctuation induced electromagnetic forces and enhanced hear transfer atmore » short separations.« less

Non-Intrusive Laser-Induced Imaging for Speciation and Patternation in High Pressure Gas Turbine Combustors

NASA Technical Reports Server (NTRS)

Locke, Randy J.; Zaller, Michelle M.; Hicks, Yolanda R.; Anderson, Robert C.

1999-01-01

The next generation of was turbine combustors for aerospace applications will be required to meet increasingly stringent constraints on fuel efficiency, noise abatement, and emissions. The power plants being designed to meet these constraints will operate at extreme conditions of temperature and pressure, thereby generating unique challenges to the previously employed diagnostic methodologies. Current efforts at NASA Glenn Research Center (GRC) utilize optically accessible, high pressure flametubes and sector combustor rigs to probe, via advanced nonintrusive laser techniques, the complex flowfields encountered in advanced combustor designs. The fuel-air mixing process is of particular concern for lowering NO(x) emissions generated in lean, premixed engine concepts. Using planar laser-induced fluorescence (PLIF) we have obtained real-time, detailed imaging of the fuel spray distribution for a number of fuel injector over a wide range of operational conditions that closely match those expected in the proposed propulsion systems. Using a novel combination of planar imaging, of fuel fluorescence and computational analysis that allows an examination of the flowfield from any perspective, we have produced spatially and temporally resolved fuel-air distribution maps. These maps provide detailed insight into the fuel injection at actual conditions never before possible, thereby greatly enhancing the evaluation of fuel injector performance and combustion phenomena.

OH Planar Laser Induced Fluorescence (PLIF) Measurements for the Study of High Pressure Flames: An Evaluation of a New Laser and a New Camera System

NASA Technical Reports Server (NTRS)

Tedder, Sarah; Hicks, Yolanda

2012-01-01

Planar laser induced fluorescence (PLIF) is used by the Combustion Branch at the NASA Glenn Research Center (NASA Glenn) to assess the characteristics of the flowfield produced by aircraft fuel injectors. To improve and expand the capabilities of the PLIF system new equipment was installed. The new capabilities of the modified PLIF system are assessed by collecting OH PLIF in a methane/air flame produced by a flat flame burner. Specifically, the modifications characterized are the addition of an injection seeder to a Nd:YAG laser pumping an optical parametric oscillator (OPO) and the use of a new camera with an interline CCD. OH fluorescence results using the injection seeded OPO laser are compared to results using a Nd:YAG pumped dye laser with ultraviolet extender (UVX). Best settings of the new camera for maximum detection of PLIF signal are reported for the controller gain and microchannel plate (MCP) bracket pulsing. Results are also reported from tests of the Dual Image Feature (DIF) mode of the new camera which allows image pairs to be acquired in rapid succession. This allows acquisition of a PLIF image and a background signal almost simultaneously. Saturation effects in the new camera were also investigated and are reported.

Nonintrusive laser-induced imaging for speciation and patternation in high-pressure gas turbine combustors

NASA Astrophysics Data System (ADS)

Locke, Randy J.; Zaller, Michelle M.; Hicks, Yolanda R.; Anderson, Robert C.

1999-10-01

The next generation of ga turbine combustors for aerospace applications will be required to meet increasingly stringent constraints on fuel efficiency, noise abatement, and emissions. The power plants being designed to meet these constraints will operate at extreme conditions of temperature and pressure, thereby generating unique challenges to the previously employed diagnostic methodologies. Current efforts at NASA Glenn Research Center GRC utilize optically accessible, high-pressure flametubes and sector combustor rigs to probe, via advanced nonintrusive laser techniques, the complex flowfields encountered in advanced combustor designs. The fuel-air mixing process is of particular concern for lowering NOx emissions generated in lean, premixed engine concepts. Using planar laser-induced fluorescence we have obtained real- time, detailed imaging of the fuel spray distribution for a number of fuel injectors over a wide range of operational conditions that closely match those expected in the proposed propulsion systems. Using a novel combination of planar imaging of fuel fluorescence and computational analysis that allows an examination of the flowfield from any perspective, we have produced spatially and temporally resolved fuel-air distribution maps. These maps provide detailed insight into the fuel injection process at actual conditions never before possible, thereby greatly enhancing the evaluation of fuel injector performance and combustion phenomena.

Electro-optic crystal mosaics for the generation of terahertz radiation

DOEpatents

Carrig, Timothy J.; Taylor, Antoinette J.; Stewart, Kevin R.

1996-01-01

Apparatus for the generation of high energy terahertz radiation is presented and comprises laser means effective to produce subpicosecond optical pulses and a mosaic comprising a plurality of planar electro-optic crystals fastened together edge to edge in the form of a grid. The electro-optic crystals are in optical communication with the subpicosecond optical pulses, and behave as a single large electro-optic crystal, producing high energy terahertz radiation by way of optical rectification.

Electro-optic crystal mosaics for the generation of terahertz radiation

DOEpatents

Carrig, T.J.; Taylor, A.J.; Stewart, K.R.

1996-08-06

Apparatus for the generation of high energy terahertz radiation is presented and comprises laser means effective to produce subpicosecond optical pulses and a mosaic comprising a plurality of planar electro-optic crystals fastened together edge to edge in the form of a grid. The electro-optic crystals are in optical communication with the subpicosecond optical pulses, and behave as a single large electro-optic crystal, producing high energy terahertz radiation by way of optical rectification. 5 figs.

Optimized micromirror arrays for adaptive optics

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

Michalicek, M. Adrian

This paper describes the design, layout, fabrication, and surface characterization of highly optimized surface micromachined micromirror devices. Design considerations and fabrication capabilities are presented. These devices are fabricated in the state-of-the-art, four-level, planarized, ultra-low-stress polysilicon process available at Sandia National Laboratories known as the Sandia Ultra-planar Multi-level MEMS Technology (SUMMiT). This enabling process permits the development of micromirror devices with near-ideal characteristics that have previously been unrealizable in standard three-layer polysilicon processes. The reduced 1 {mu}m minimum feature sizes and 0.1 {mu}m mask resolution make it possible to produce dense wiring patterns and irregularly shaped flexures. Likewise, mirror surfaces canmore » be uniquely distributed and segmented in advanced patterns and often irregular shapes in order to minimize wavefront error across the pupil. The ultra-low-stress polysilicon and planarized upper layer allow designers to make larger and more complex micromirrors of varying shape and surface area within an array while maintaining uniform performance of optical surfaces. Powerful layout functions of the AutoCAD editor simplify the design of advanced micromirror arrays and make it possible to optimize devices according to the capabilities of the fabrication process. Micromirrors fabricated in this process have demonstrated a surface variance across the array from only 2{endash}3 nm to a worst case of roughly 25 nm while boasting active surface areas of 98{percent} or better. Combining the process planarization with a {open_quotes}planarized-by-design{close_quotes} approach will produce micromirror array surfaces that are limited in flatness only by the surface deposition roughness of the structural material. Ultimately, the combination of advanced process and layout capabilities have permitted the fabrication of highly optimized micromirror arrays for adaptive optics. {copyright} {ital 1999 American Institute of Physics.}« less

Towards do-it-yourself planar optical components using plasmon-assisted etching.

PubMed

Chen, Hao; Bhuiya, Abdul M; Ding, Qing; Johnson, Harley T; Toussaint, Kimani C

2016-01-27

In recent years, the push to foster increased technological innovation and basic scientific and engineering interest from the broadest sectors of society has helped to accelerate the development of do-it-yourself (DIY) components, particularly those related to low-cost microcontroller boards. The attraction with DIY kits is the simplification of the intervening steps going from basic design to fabrication, albeit typically at the expense of quality. We present herein plasmon-assisted etching as an approach to extend the DIY theme to optics, specifically the table-top fabrication of planar optical components. By operating in the design space between metasurfaces and traditional flat optical components, we employ arrays of Au pillar-supported bowtie nanoantennas as a template structure. To demonstrate, we fabricate a Fresnel zone plate, diffraction grating and holographic mode converter--all using the same template. Applications to nanotweezers and fabricating heterogeneous nanoantennas are also shown.

Towards do-it-yourself planar optical components using plasmon-assisted etching

NASA Astrophysics Data System (ADS)

Chen, Hao; Bhuiya, Abdul M.; Ding, Qing; Johnson, Harley T.; Toussaint, Kimani C., Jr.

2016-01-01

In recent years, the push to foster increased technological innovation and basic scientific and engineering interest from the broadest sectors of society has helped to accelerate the development of do-it-yourself (DIY) components, particularly those related to low-cost microcontroller boards. The attraction with DIY kits is the simplification of the intervening steps going from basic design to fabrication, albeit typically at the expense of quality. We present herein plasmon-assisted etching as an approach to extend the DIY theme to optics, specifically the table-top fabrication of planar optical components. By operating in the design space between metasurfaces and traditional flat optical components, we employ arrays of Au pillar-supported bowtie nanoantennas as a template structure. To demonstrate, we fabricate a Fresnel zone plate, diffraction grating and holographic mode converter--all using the same template. Applications to nanotweezers and fabricating heterogeneous nanoantennas are also shown.

Towards do-it-yourself planar optical components using plasmon-assisted etching

PubMed Central

Chen, Hao; Bhuiya, Abdul M.; Ding, Qing; Johnson, Harley T.; Toussaint Jr, Kimani C.

2016-01-01

In recent years, the push to foster increased technological innovation and basic scientific and engineering interest from the broadest sectors of society has helped to accelerate the development of do-it-yourself (DIY) components, particularly those related to low-cost microcontroller boards. The attraction with DIY kits is the simplification of the intervening steps going from basic design to fabrication, albeit typically at the expense of quality. We present herein plasmon-assisted etching as an approach to extend the DIY theme to optics, specifically the table-top fabrication of planar optical components. By operating in the design space between metasurfaces and traditional flat optical components, we employ arrays of Au pillar-supported bowtie nanoantennas as a template structure. To demonstrate, we fabricate a Fresnel zone plate, diffraction grating and holographic mode converter—all using the same template. Applications to nanotweezers and fabricating heterogeneous nanoantennas are also shown. PMID:26814026

Luneburg lens and optical matrix algebra research

NASA Technical Reports Server (NTRS)

Wood, V. E.; Busch, J. R.; Verber, C. M.; Caulfield, H. J.

1984-01-01

Planar, as opposed to channelized, integrated optical circuits (IOCs) were stressed as the basis for computational devices. Both fully-parallel and systolic architectures are considered and the tradeoffs between the two device types are discussed. The Kalman filter approach is a most important computational method for many NASA problems. This approach to deriving a best-fit estimate for the state vector describing a large system leads to matrix sizes which are beyond the predicted capacities of planar IOCs. This problem is overcome by matrix partitioning, and several architectures for accomplishing this are described. The Luneburg lens work has involved development of lens design techniques, design of mask arrangements for producing lenses of desired shape, investigation of optical and chemical properties of arsenic trisulfide films, deposition of lenses both by thermal evaporation and by RF sputtering, optical testing of these lenses, modification of lens properties through ultraviolet irradiation, and comparison of measured lens properties with those expected from ray trace analyses.

The membrane-permeabilizing effect of avenacin A-1 involves the reorganization of bilayer cholesterol.

PubMed Central

Armah, C N; Mackie, A R; Roy, C; Price, K; Osbourn, A E; Bowyer, P; Ladha, S

1999-01-01

Avenacin A-1 is a member of a group of naturally occurring compounds called saponins. It is found in oat plants, where it protects against fungal pathogens. A combined electrical and optical chamber was used to determine the interaction of avenacin A-1 with Montal-Mueller planar lipid bilayers. This system allowed simultaneous measurement of the effect of avenacin A-1 on the fluorescence and lateral diffusion of a fluorescent lipid probe and permeability of the planar lipid bilayer. As expected, cholesterol was required for avenacin A-1-induced bilayer permeabilization. The planar lipid bilayers were also challenged with monodeglucosyl, bis-deglucosyl, and aglycone derivatives of avenacin A-1. The results show that the permeabilizing activity of the native avenacin A-1 was completely abolished after one, two, or all three sugar residues are hydrolyzed (monodeglucosyl, bis-deglucosyl, and aglycone derivatives, respectively). Fluorescence recovery after photobleaching (FRAP) measurements on cholesterol-containing planar lipid bilayers revealed that avenacin A-1 caused a small but significant reduction in the lateral diffusion of the phospholipid probe N-(7-nitrobenzoyl-2-oxa-1,3-diazol-4-yl)-1, 2-dihexadecanoyl-sn-glycero-3-phosphoethanolamine (NBD-PE). Similarly, with the sterol probe (22-(N-(7-nitrobenz-2-oxa-1, 3-diazol-4-yl)amino)-23,24-bisnor-5-cholen-3beta-ol (NBD-Chol), avenacin A-1, but not its derivatives, caused a more pronounced reduction in the lateral diffusion than that observed with the phospholipid probe. The data indicate that an intact sugar moiety of avenacin A-1 is required to reorganize membrane cholesterol into pores. PMID:9876141

Design and fabrication of N x N optical couplers based on organic polymer optical waveguides

NASA Astrophysics Data System (ADS)

Krchnavek, Robert R.; Rode, Daniel L.

1994-08-01

In this report, we examine the design and fabrication of a planar, 10x10 optical coupler utilizing photopolymerizable organic polymers. Background information on the theory of operation of the coupler culminating in a set of design equations is presented. The details of the material processing are described, including the preparation of monomer mixtures that result in single-mode polymer waveguides (lambda = 1300 nm) that have core dimensions approximately equal to those of single-mode fiber. This is necessary to insure high coupling efficiency between the planar device and optical fiber. A unique method of aligning and attaching optical fibers to the coupler is demonstrated. This method relies on patterned alignment ways, a transcision cut, and single-mode D-fiber. A theoretical analysis of the in situ monitoring technique used to fabricate the single-mode D-fiber is presented and compared favorably with the experimental results. Finally, the 10x10 coupler is characterized. We have measured an excess loss of approximately 8 dB.

Bi-directional triplexer with butterfly MMI coupler using SU-8 polymer waveguides

NASA Astrophysics Data System (ADS)

Mareš, David; Jeřábek, Vítězslav; Prajzler, Václav

2015-01-01

We report about a design of a bi-directional planar optical multiplex/demultiplex filter (triplexer) for the optical part of planar hybrid WDM bi-directional transceiver in fiber-to-the-home (FTTH) PON applications. The triplex lightwave circuit is based on the Epoxy Novolak Resin SU-8 waveguides on the silica-on-silicon substrate with Polymethylmethacrylate cladding layer. The triplexer is comprised of a linear butterfly concept of multimode interference (MMI) coupler separating downstream optical signals of 1490 nm and 1550 nm. For the upstream channel of 1310 nm, an additional directional coupler (DC) is used to add optical signal of 1310 nm propagating in opposite direction. The optical triplexer was designed and optimized using beam propagation method. The insertion losses, crosstalk attenuation, and extinction ratio for all three inputs/outputs were investigated. The intended triplexer was designed using the parameters of the separated DC and MMI filter to approximate the idealized direct connection of both devices.

Minimization theory of induced drag subject to constraint conditions

NASA Technical Reports Server (NTRS)

Deyoung, J.

1979-01-01

Exact analytical solutions in terms of induced drag influence coefficients can be attained which define the spanwise loading with minimized induced drag, subject to specified constraint conditions, for any nonplanar wing shape or number of lift plus wing bending moment about a given wing span station. Example applications of the theory are made to a biplane, a wing in ground effect, a cruciform wing, a V-wing, a planar-wing winglet, and linked wingtips in formation flying. For minimal induced drag, the spanwise loading, relative to elliptic, is outboard for the biplane and is inboard for the wing in ground effect and for the planar-wing winglet. A spinoff of the triplane solution provides mathematically exact equations for downwash and sidewash about a planar vorticity sheet having an arbitrary loading distribution.

Curved focusing crystals for hard X-ray astronomy

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

Ferrari, C., E-mail: ferrari@imem.cnr.it; Buffagni, E.; Bonnini, E.

A lens made by a properly arranged array of crystals can be used to focus x-rays of energy ranging from 30 to 500 keV for x-ray astronomy. Mosaic or curved crystals can be employed as x-ray optical elements. In this work self standing curved focusing Si and GaAs crystals in which the lattice bending is induced by a controlled damaging process on one side of planar crystals are characterized. Diffraction profiles in Laue geometry have been measured in crystals at x-ray energies E = 17, 59 and 120 keV. An enhancement of diffraction efficiency is found in asymmetric geometries.

Investigation of Carbon-Polymer Structures with Embedded Fiber-Optic Bragg Gratings

NASA Technical Reports Server (NTRS)

Grant, Joseph; Kaul, R.; Taylor, S.; Myers, G.; Sharma, A.

2003-01-01

Several Bragg-grating sensors fabricated within the same optical fiber are buried within multiple-ply carbon-epoxy planar and cylindrical structures. Effect of different orientation of fiber-sensors with respect to carbon fibers in the composite structure is investigated. This is done for both fabric and uni-tape material samples. Response of planar structures to axial and transverse strain up to 1 millistrain is investigated with distributed Bragg-grating sensors. Material properties like Young's Modulus and Poisson ratio is measured. A comparison is made between response measured by sensors in different ply-layers and those bonded on the surface. The results from buried fiber- sensors do not completely agree with surface bonded conventional strain gauges. A plausible explanation is given for observed differences. The planar structures are subjected to impacts with energies up to 10 ft-lb. Effect of this impact on the material stiffness is also investigated with buried fiber-optic Bragg sensors. The strain response of such optical sensors is also measured for cylindrical carbon-epoxy composite structures. The sensors are buried within the walls of the cylinder as well as surface bonded in both the axial as well as hoop directions. The response of these fiber-optic sensors is investigated by pressurizing the cylinder up to its burst pressure of around 1500 psi. This is done at both room temperature as well as cryogenic temperatures. The recorded response is compared with that from a conventional strain gauge.

Estimation of polarization distribution on gold nanorods system from hierarchical features of optical near-field

NASA Astrophysics Data System (ADS)

Uchiyama, Kazuharu; Nishikawa, Naoki; Nakagomi, Ryo; Kobayashi, Kiyoshi; Hori, Hirokazu

2018-02-01

To design optoelectronic functionalities in nanometer scale based on interactions of electronic system with optical near-fields, it is essential to evaluate the relationship between optical near-fields and their sources. Several theoretical studies have been performed, so far, to analyze such complex relationship to design the interaction fields of several specific scales. In this study, we have performed detailed and high-precision measurements of optical near-field structures woven by a large number of independent polarizations generated in the gold nanorods array under laser light irradiation at the resonant frequency. We have accumulated the multi-layered data of optical near-field imaging at different heights above the planar surface with the resolution of several nm by a STM-assisted scanning near-field optical microscope. Based on these data, we have performed an inverse calculation to estimate the position, direction, and strength of the local polarization buried under the flat surface of the sample. As a result of the inverse operation, we have confirmed that the complexities in the nanometer scale optical near-fields could be reconstructed by combinations of induced polarization in each gold nanorod. We have demonstrated the hierarchical properties of optical near-fields based on spatial frequency expansion and superposition of dipole fields to provide insightful information for applications such for secure multi-layered information storage.

Phyllotactic arrangements of optical elements

NASA Astrophysics Data System (ADS)

Horacek, M.; Meluzin, P.; Kratky, S.; Matejka, M.; Kolarik, V.

2017-05-01

Phyllotaxy studies arrangements of biological entities, e.g. a placement of seeds in the flower head. Vogel (1979) presented a phyllotactic model based on series of seeds ordered along a primary spiral. This arrangement allows each seed to occupy the same area within a circular flower head. Recently, a similar arrangement of diffraction primitives forming a planar relief diffractive structure was presented. The planar relief structure was used for benchmarking and testing purposes of the electron beam writer patterning process. This contribution presents the analysis of local periods and azimuths of optical phyllotactic arrangements. Two kinds of network characteristic triangles are introduced. If the discussed planar structure has appropriate size and density, diffraction of the incoming light creates characteristic a phyllotactic diffraction pattern. Algorithms enabling the analysis of such behavior were developed and they were validated by fabricated samples of relief structures. Combined and higher diffraction orders are also analyzed. Different approaches enabling the creation of phyllotactic diffractive patterns are proposed. E-beam lithography is a flexible technology for various diffraction gratings origination. The e-beam patterning typically allows for the creation of optical diffraction gratings in the first diffraction order. Nevertheless, this technology enables also more complex grating to be prepared, e.g. blazed gratings and zero order gratings. Moreover, the mentioned kinds of gratings can be combined within one planar relief structure. The practical part of the presented work deals with the nano patterning of such structures by using two different types of the e-beam pattern generators.

FIBRE AND INTEGRATED OPTICS. OPTICAL PROCESSING OF INFORMATION: Mechanism of lock-in detection with the aid of an alternating field perpendicular to the surface of a planar photorefractive waveguide

NASA Astrophysics Data System (ADS)

Zel'dovich, Boris Ya; Miklyaev, Yu V.; Safonov, V. I.

1995-02-01

An analysis is made of the mechanism of formation of a stationary grating in a planar photorefractive waveguide by a travelling interference pattern with the aid of an alternating electric field applied perpendicular to the waveguide layer. A theoretical calculation is reported of the distribution of the space-charge field in a transverse section of the waveguide. Finite drift lengths and trap saturation are taken into account in these calculations, which are carried out on the assumption of a weak contrast in the interference pattern.

Polymer planar lightwave circuit based hybrid-integrated coherent receiver for advanced modulation signals

NASA Astrophysics Data System (ADS)

Wang, Jin; Han, Yang; Liang, Zhongcheng; Chen, Yongjin

2012-11-01

Applying coherent detection technique to advanced modulation formats makes it possible to electronically compensate the signal impairments. A key issue for a successful deployment of coherent detection technique is the availability of cost-efficient and compact integrated receivers, which are composed of an optical 90° hybrid mixer and four photodiodes (PDs). In this work, three different types of optical hybrids are fabricated with polymer planar lightwave circuit (PLC), and hybridly integrated with four vertical backside illuminated III-V PDs. Their performances, such as the insertion loss, the transmission imbalance, the polarization dependence and the phase deviation of 90° hybrid will be discussed.

Optical device terahertz integration in a two-dimensional-three-dimensional heterostructure.

PubMed

Feng, Zhifang; Lin, Jie; Feng, Shuai

2018-01-10

The transmission properties of an off-planar integrated circuit including two wavelength division demultiplexers are designed, simulated, and analyzed in detail by the finite-difference time-domain method. The results show that the wavelength selection for different ports (0.404[c/a] at B 2 port, 0.389[c/a] at B 3 port, and 0.394[c/a] at B 4 port) can be realized by adjusting the parameters. It is especially important that the off-planar integration between two complex devices is also realized. These simulated results give valuable promotions in the all-optical integrated circuit, especially in compact integration.

Tuning optical properties of opal photonic crystals by structural defects engineering

NASA Astrophysics Data System (ADS)

di Stasio, F.; Cucini, M.; Berti, L.; Comoretto, D.; Abbotto, A.; Bellotto, L.; Manfredi, N.; Marinzi, C.

2009-06-01

We report on the preparation and optical characterization of three dimensional colloidal photonic crystal (PhC) containing an engineered planar defect embedding photoactive push-pull dyes. Free standing polystyrene films having thickness between 0.6 and 3 mm doped with different dipolar chromophores were prepared. These films were sandwiched between two artificial opals creating a PhC structure with planar defect. The system was characterized by reflectance at normal incidence angle (R), variable angle transmittance (T) and photoluminescence spectroscopy (PL) Evidence of defect states were observed in T and R spectra which allow the light to propagate for selected frequencies within the pseudogap (stop band).

Two-dimensional complex source point solutions: application to propagationally invariant beams, optical fiber modes, planar waveguides, and plasmonic devices.

PubMed

Sheppard, Colin J R; Kou, Shan S; Lin, Jiao

2014-12-01

Highly convergent beam modes in two dimensions are considered based on rigorous solutions of the scalar wave (Helmholtz) equation, using the complex source point formalism. The modes are applicable to planar waveguide or surface plasmonic structures and nearly concentric microcavity resonator modes in two dimensions. A novel solution is that of a vortex beam, where the direction of propagation is in the plane of the vortex. The modes also can be used as a basis for the cross section of propagationally invariant beams in three dimensions and bow-tie-shaped optical fiber modes.

Integrated Optics for Planar imaging and Optical Signal Processing

NASA Astrophysics Data System (ADS)

Song, Qi

Silicon photonics is a subject of growing interest with the potential of delivering planar electro-optical devices with chip scale integration. Silicon-on-insulator (SOI) technology has provided a marvelous platform for photonics industry because of its advantages in integration capability in CMOS circuit and countless nonlinearity applications in optical signal processing. This thesis is focused on the investigation of planar imaging techniques on SOI platform and potential applications in ultra-fast optical signal processing. In the first part, a general review and background introduction about integrated photonics circuit and planar imaging technique are provided. In chapter 2, planar imaging platform is realized by a silicon photodiode on SOI chip. Silicon photodiode on waveguide provides a high numerical aperture for an imaging transceiver pixel. An erbium doped Y2O3 particle is excited by 1550nm Laser and the fluorescent image is obtained with assistance of the scanning system. Fluorescence image is reconstructed by using image de-convolution technique. Under photovoltaic mode, we use an on-chip photodiode and an external PIN photodiode to realize similar resolution as 5μm. In chapter 3, a time stretching technique is developed to a spatial domain to realize a 2D imaging system as an ultrafast imaging tool. The system is evaluated based on theoretical calculation. The experimental results are shown for a verification of system capability to imaging a micron size particle or a finger print. Meanwhile, dynamic information for a moving object is also achieved by correlation algorithm. In chapter 4, the optical leaky wave antenna based on SOI waveguide has been utilized for imaging applications and extensive numerical studied has been conducted. and the theoretical explanation is supported by leaky wave theory. The highly directive radiation has been obtained from the broadside with 15.7 dB directivity and a 3dB beam width of ΔØ 3dB ≈ 1.65° in free space environment when β -1 = 2.409 × 105/m, α=4.576 ×103/m. At the end, electronics beam-steering principle has been studied and the comprehensive model has been built to explain carrier transformation behavior in a PIN junction as individual silicon perturbation. Results show that 1019/cm3 is possible obtained with electron injection mechanism. Although the radiation modulation based on carrier injection of 1019/cm3 gives 0.5dB variation, resonant structure, such as Fabry Perrot Cavity, can be integrated with LOWAs to enhance modulation effect.

The formation and optical properties of planar waveguide in laser crystal Nd:YGG by carbon ion implantation

NASA Astrophysics Data System (ADS)

Zhao, Jin-Hua; Qin, Xi-Feng; Wang, Feng-Xiang; Jiao, Yang; Guan, Jing; Fu, Gang

2017-10-01

As one kind of prominent laser crystal, Nd:Y3Ga5O12 (Nd:YGG) crystal has outstanding performance on laser excitation at multi-wavelength which have shown promising applications in optical communication field. In addition, Nd:YGG crystal has potential applications in medical field due to its ability of emit the laser at 1110 nm. Optical waveguide structure with high quality could improve the efficiency of laser emission. In this work, we fabricated the optical planar waveguide on Nd:YGG crystal by medium mass ion implantation which was convinced an effective method to realize a waveguide structure with superior optical properties. The sample is implanted by C ions at energy of 5.0 MeV with the fluence of 1 × 1015 ions/cm2. We researched the optical propagation properties in the Nd:YGG waveguide by end-face coupling and prism coupling method. The Nd ions fluorescent properties are obtained by a confocal micro-luminescence measurement. The fluorescent properties of Nd ions obtained good reservation after C ion implantation. Our work has reference value for the application of Nd:YGG crystal in the field of optical communication.

Measurement of six-degree-of-freedom planar motions by using a multiprobe surface encoder

NASA Astrophysics Data System (ADS)

Li, Xinghui; Shimizu, Yuki; Ito, Takeshi; Cai, Yindi; Ito, So; Gao, Wei

2014-12-01

A multiprobe surface encoder for optical metrology of six-degree-of-freedom (six-DOF) planar motions is presented. The surface encoder is composed of an XY planar scale grating with identical microstructures in X- and Y-axes and an optical sensor head. In the optical sensor head, three paralleled laser beams were used as laser probes. After being divided by a beam splitter, the three laser probes were projected onto the scale grating and a reference grating with identical microstructures, respectively. For each probe, the first-order positive and negative diffraction beams along the X- and Y-directions from the scale grating and from the reference grating superimposed with each other and four pieces of interference signals were generated. Three-DOF translational motions of the scale grating Δx, Δy, and Δz can be obtained simultaneously from the interference signals of each probe. Three-DOF angular error motions θX, θY, and θZ can also be calculated simultaneously from differences of displacement output variations and the geometric relationship among the three probes. A prototype optical sensor head was designed, constructed, and evaluated. Experimental results verified that this surface encoder could provide measurement resolutions of subnanometer and better than 0.1 arc sec for three-DOF translational motions and three-DOF angular error motions, respectively.

A novel method for correction of temporally- and spatially-variant optical distortion in planar particle image velocimetry

DOE PAGES

Zha, Kan; Busch, Stephen; Park, Cheolwoong; ...

2016-06-24

In-cylinder flow measurements are necessary to gain a fundamental understanding of swirl-supported, light-duty Diesel engine processes for high thermal efficiency and low emissions. Planar particle image velocimetry (PIV) can be used for non-intrusive, in situ measurement of swirl-plane velocity fields through a transparent piston. In order to keep the flow unchanged from all-metal engine operation, the geometry of the transparent piston must adapt the production-intent metal piston geometry. As a result, a temporally- and spatially-variant optical distortion is introduced to the particle images. Here, to ensure reliable measurement of particle displacements, this work documents a systematic exploration of optical distortionmore » quantification and a hybrid back-projection procedure that combines ray-tracing-based geometric and in situ manual back-projection approaches.« less

Optical and TEM study of shock metamorphism from the Sedan test site

NASA Technical Reports Server (NTRS)

Gratz, A. J.

1992-01-01

Thus far, detailed petrologic studies of shock metamorphism have been performed on samples recovered from laboratory experiments and on a few natural impactites. The loading history of these samples is quite different: In particular, laboratory experiments spend only a short time (less than 1 microsec) at peak pressure, whereas natural impactites may have stress pulses from 0.1 - 1 ms. On the other hand, laboratory experiments have known stress histories; natural impactites do not. Natural samples are also subjected to thousands or millions of years of postshock annealing and/or weathering. A useful intermediate case is that of nuclear detonation. Stress pulses for these events can reach 0.1 ms or higher, and samples are obtained in pristine condition. All three types of loading produce stresses of hundreds of kilobars. Samples studied were taken from the Sedan nulcear test site, and consist of a coarse-grained granodiorite containing quartz, K-feldspar, cordierite, and hornblende. Samples were studied optically in this section, then were thinned with an ion mill and studied by transmission electron microscopy (TEM). Optically, quartz and K-feldspar displayed numerous sets of planar deformation features (PDF's) identical to the nondecorated PDF's seen in laboratory samples and many natural impactites. TEM study showed that the PDF's in quartz and feldspar corresponded to densely packed wide transformation lamellae identical to those described in laboratory studies. The transformation lamellae in both minerals were amorphous, with no sign of high-pressure phases. In the case of K-feldspar only, narrow sublamellae extended outward from some wide lamellae. Quartz, which was more abundant and studied more extensively, contained no shock-induced dislocations. Some planar features were also seen in cordierite, but could not be identified due to rapid beam damage. No shock defects were seen in hornblende in TEM. The shock-induced defects present at the Sedan site are very similar to those seen in shock recovery experiments, and also to those present at certain natural events (e.g., Meteor Crater). This suggests that shock deformation in quartz is not strongly dependent on shock pulse duration, and that laboratory recovery experiments are useful simulations of natural impact events.

Cascaded all-optical operations in a hybrid integrated 80-Gb/s logic circuit.

PubMed

LeGrange, J D; Dinu, M; Sochor, T; Bollond, P; Kasper, A; Cabot, S; Johnson, G S; Kang, I; Grant, A; Kay, J; Jaques, J

2014-06-02

We demonstrate logic functionalities in a high-speed all-optical logic circuit based on differential Mach-Zehnder interferometers with semiconductor optical amplifiers as the nonlinear optical elements. The circuit, implemented by hybrid integration of the semiconductor optical amplifiers on a planar lightwave circuit platform fabricated in silica glass, can be flexibly configured to realize a variety of Boolean logic gates. We present both simulations and experimental demonstrations of cascaded all-optical operations for 80-Gb/s on-off keyed data.

Polymer electro-optic waveguide devices: Low-loss etchless fabrication techniques and passive-to-active integration

NASA Astrophysics Data System (ADS)

Geary, Kevin

The development of high-frequency polymer electro-optic modulators has seen steady and significant progress in recent years, yet applications of these promising materials to more complicated integrated optic structures and arrays of devices have been limited primarily due to high optical waveguide loss characteristics. This is unfortunate since a major advantage of polymers as photonic materials is their compatibility with photolithographic processing of large components. In this Dissertation, etchless waveguide writing techniques are presented in order to improve the overall optical insertion loss of electro-optic polymer waveguide devices. These techniques include poling-induced writing, stress-induced waveguide writing, and photobleaching. Using these waveguide writing mechanisms, we have demonstrated straight waveguides, phase modulators, Mach-Zehnder intensity modulators, variable optical attenuators, and multimode interference (MMI) power splitters, all with improved loss characteristics over their etched rib waveguide counterparts. Ultimately, the insertion loss of an integrated optic device is limited by the actual material loss of the core waveguide material. In this Dissertation, passive-to-active polymer waveguide transitions are proposed to circumvent this problem. These transitions are compact, in-plane, self-aligned, and require no tapering of any physical dimensions of the waveguides. By utilizing both the time-dependent and intensity-dependent photobleaching characteristics of electro-optic polymer materials, adiabatic refractive index tapers can be seamlessly coupled to in-plane butt couple transitions, resulting in losses as low as 0.1 dB per interface. By integrating passive polymer planar lightwave circuits with the high-speed phase shifting capability of electro-optic polymers, active wideband photonic devices of increased size and complexity can be realized. Optical fiber-to-device coupling can also result in significant contributions to the overall insertion loss of an integrated electro-optic polymer device. In this Dissertation, we leverage the photobleached refractive index taper component of our proposed passive-to-active polymer waveguide transitions in order to realize a two-dimensional optical mode transformer for improved overall fiber-to-device coupling of electro-optic polymer waveguide devices.

Planar concentrators near the étendue limit.

PubMed

Winston, Roland; Gordon, Jeffrey M

2005-10-01

Recently proposed aplanatic imaging designs are integrally combined with nonimaging flux boosters to produce an ultracompact planar glass-filled concentrator that performs near the étendue limit. Such optical devices are attractive for high-efficiency multijunction photovoltaics at high flux, with realistic power generation of 1 W from a 1 mm2 cell. When deployed in reverse, our designs provide collimation even for high-numerical-aperture light sources.

Planar concentrators near the étendue limit

NASA Astrophysics Data System (ADS)

Winston, Roland; Gordon, Jeffrey M.

2005-10-01

Recently proposed aplanatic imaging designs are integrally combined with nonimaging flux boosters to produce an ultracompact planar glass-filled concentrator that performs near the étendue limit. Such optical devices are attractive for high-efficiency multijunction photovoltaics at high flux, with realistic power generation of 1 W from a 1 mm² cell. When deployed in reverse, our designs provide collimation even for high-numerical-aperture light sources.

Influence of plasmon destructive interferences on optical properties of gold planar quadrumers.

PubMed

Rahmani, M; Tahmasebi, T; Lin, Y; Lukiyanchuk, B; Liew, T Y F; Hong, M H

2011-06-17

Arrays of planar symmetric gold quadrumers consisting of a central nano-disc surrounded by three similar nano-discs belonging to the D(3h) point group were designed and fabricated. Since the geometrical configuration of quadrumers is the same as planar trigonal molecules, nano-discs can play the roles of artificial atoms to study the coupling trends among them. The plasmonic properties of the nano-disc structures are investigated by reflection spectrum measurement and finite-difference time-domain calculation with good agreement. Plasmon interaction among the nano-discs is also studied via a mass-spring coupled oscillator model. A pronounced Fano resonance (FR) is observed for the fabricated nano-discs with inter-disk gaps of around 18 nm during light irradiation at normal incidence. Although the obtained FR is independent of the excitation polarization, the near-field energy spatial distribution can be flexibly tuned by the polarization direction. This has potential applications in nano-lithography, optical switching and nonlinear spectroscopy.

Dimensional effects on the magnetic domains in planar magnetophotonic crystal waveguides

NASA Astrophysics Data System (ADS)

Huang, Xiaoyue

2007-05-01

The application of photonic crystal technology in magneto-optic media can yield significant improvements in polarization rotation efficiency and optical switching capability and an overall reduction in magneto-optic device dimensions. Resonant photonic crystal structures in planar ferrimagnetic film waveguides are of interest because they may lead to the development of on-chip magneto-optical switches and isolators for photonic device integration. In the present work, two different methods for the fabrication of on-chip waveguide magnetophotonic crystals, through electron beam lithography and focused ion beam milling, are discussed and demonstrated. A high precision photonic measurement system was set up for testing and analysis of the waveguide devices. The results obtained show photonic band gaps with resonant transmission in the gap, and enhanced magneto-optic rotation efficiency. The character of waveguide modes therein, birefringence effects, and structural variation effects were studied extensively and are presented in this thesis. Planar magnetization control produced by manipulation of the magnetic shape anisotropy in the photonic crystal micro-cavity was demonstrated in this work. By introducing strip structures into the resonant cavity formed on magnetic garnet films with in-plane anisotropy, a bi-stable magnetic state and an enhanced magnetic field reversal mechanism were demonstrated. This effect was extensively studied through experimental and micromagnetic simulation analysis of the polarization rotation hysteresis. The results discussed herein show that domain closure loops between the strips limit the magnification of the coercivity in the resonant cavity and that these limitations can be overcome by the formation of isolated single-domain magnetic microstrips in the cavity.

Planar and finger-shaped optical tactile sensors for robotic applications

NASA Technical Reports Server (NTRS)

Begej, Stefan

1988-01-01

Progress is described regarding the development of optical tactile sensors specifically designed for application to dexterous robotics. These sensors operate on optical principles involving the frustration of total internal reflection at a waveguide/elastomer interface and produce a grey-scale tactile image that represents the normal (vertical) forces of contact. The first tactile sensor discussed is a compact, 32 x 32 planar sensor array intended for mounting on a parallel-jaw gripper. Optical fibers were employed to convey the tactile image to a CCD camera and microprocessor-based image analysis system. The second sensor had the shape and size of a human fingertip and was designed for a dexterous robotic hand. It contained 256 sensing sites (taxels) distributed in a dual-density pattern that included a tactile fovea near the tip measuring 13 x 13 mm and containing 169 taxels. The design and construction details of these tactile sensors are presented, in addition to photographs of tactile imprints.

Gain determination of optical active doped planar waveguides

NASA Astrophysics Data System (ADS)

Šmejcký, J.; Jeřábek, V.; Nekvindová, P.

2017-12-01

This paper summarizes the results of the gain transmission characteristics measurement carried out on the new ion exchange Ag+ - Na+ optical Er3+ and Yb3+ doped active planar waveguides realized on a silica based glass substrates. The results were used for optimization of the precursor concentration in the glass substrates. The gain measurements were performed by the time domain method using a pulse generator, as well as broadband measurement method using supercontinuum optical source in the wavelength domain. Both methods were compared and the results were graphically processed. It has been confirmed that pulse method is useful as it provides a very accurate measurement of the gain - pumping power characteristics for one wavelength. In the case of radiation spectral characteristics, our measurement exactly determined the maximum gain wavelength bandwidth of the active waveguide. The spectral characteristics of the pumped and unpumped waveguides were compared. The gain parameters of the reported silica-based glasses can be compared with the phosphate-based parameters, typically used for optical active devices application.

Planar polymer and glass graded index waveguides for data center applications

NASA Astrophysics Data System (ADS)

Pitwon, Richard; Yamauchi, Akira; Brusberg, Lars; Wang, Kai; Ishigure, Takaaki; Schröder, Henning; Neitz, Marcel; Worrall, Alex

2016-03-01

Embedded optical waveguide technology for optical printed circuit boards (OPCBs) has advanced considerably over the past decade both in terms of materials and achievable waveguide structures. Two distinct classes of planar graded index multimode waveguide have recently emerged based on polymer and glass materials. We report on the suitability of graded index polymer waveguides, fabricated using the Mosquito method, and graded index glass waveguides, fabricated using ion diffusion on thin glass foils, for deployment within future data center environments as part of an optically disaggregated architecture. To this end, we first characterize the wavelength dependent performance of different waveguide types to assess their suitability with respect to two dominant emerging multimode transceiver classes based on directly modulated 850 nm VCSELs and 1310 silicon photonics devices. Furthermore we connect the different waveguide types into an optically disaggregated data storage system and characterize their performance with respect to different common high speed data protocols used at the intra and inter rack level including 10 Gb Ethernet and Serial Attached SCSI.

Field enhancement in plasmonic nanostructures

NASA Astrophysics Data System (ADS)

Piltan, Shiva; Sievenpiper, Dan

2018-05-01

Efficient generation of charge carriers from a metallic surface is a critical challenge in a wide variety of applications including vacuum microelectronics and photo-electrochemical devices. Replacing semiconductors with vacuum/gas as the medium of electron transport offers superior speed, power, and robustness to radiation and temperature. We propose a metallic resonant surface combining optical and electrical excitations of electrons and significantly reducing powers required using plasmon-induced enhancement of confined electric field. The properties of the device are modeled using the exact solution of the time-dependent Schrödinger equation at the barrier. Measurement results exhibit strong agreement with an analytical solution, and allow us to extract the field enhancement factor at the surface. Significant photocurrents are observed using combination of {{W}} {{{c}}{{m}}}-2 optical power and 10 V DC excitation on the surface. The model suggests optical field enhancement of 3 orders of magnitude at the metal interface due to plasmonic resonance. This simple planar structure provides valuable evidence on the electron emission mechanisms involved and it can be used for implementation of semiconductor compatible vacuum devices.

Slow-Photon-Effect-Induced Photoelectrical-Conversion Efficiency Enhancement for Carbon-Quantum-Dot-Sensitized Inorganic CsPbBr3 Inverse Opal Perovskite Solar Cells.

PubMed

Zhou, Shujie; Tang, Rui; Yin, Longwei

2017-11-01

All-inorganic cesium lead halide perovskite is suggested as a promising candidate for perovskite solar cells due to its prominent thermal stability and comparable light absorption ability. Designing textured perovskite films rather than using planar-architectural perovskites can indeed optimize the optical and photoelectrical conversion performance of perovskite photovoltaics. Herein, for the first time, this study demonstrates a rational strategy for fabricating carbon quantum dot (CQD-) sensitized all-inorganic CsPbBr 3 perovskite inverse opal (IO) films via a template-assisted, spin-coating method. CsPbBr 3 IO introduces slow-photon effect from tunable photonic band gaps, displaying novel optical response property visible to naked eyes, while CQD inlaid among the IO frameworks not only broadens the light absorption range but also improves the charge transfer process. Applied in the perovskite solar cells, compared with planar CsPbBr 3 , slow-photon effect of CsPbBr 3 IO greatly enhances the light utilization, while CQD effectively facilitates the electron-hole extraction and injection process, prolongs the carrier lifetime, jointly contributing to a double-boosted power conversion efficiency (PCE) of 8.29% and an increased incident photon-to-electron conversion efficiency of up to 76.9%. The present strategy on CsPbBr 3 IO to enhance perovskite PCE can be extended to rationally design other novel optoelectronic devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Planar implantable sensor for in vivo measurement of cellular oxygen metabolism in brain tissue.

PubMed

Tsytsarev, Vassiliy; Akkentli, Fatih; Pumbo, Elena; Tang, Qinggong; Chen, Yu; Erzurumlu, Reha S; Papkovsky, Dmitri B

2017-04-01

Brain imaging methods are continually improving. Imaging of the cerebral cortex is widely used in both animal experiments and charting human brain function in health and disease. Among the animal models, the rodent cerebral cortex has been widely used because of patterned neural representation of the whiskers on the snout and relative ease of activating cortical tissue with whisker stimulation. We tested a new planar solid-state oxygen sensor comprising a polymeric film with a phosphorescent oxygen-sensitive coating on the working side, to monitor dynamics of oxygen metabolism in the cerebral cortex following sensory stimulation. Sensory stimulation led to changes in oxygenation and deoxygenation processes of activated areas in the barrel cortex. We demonstrate the possibility of dynamic mapping of relative changes in oxygenation in live mouse brain tissue with such a sensor. Oxygenation-based functional magnetic resonance imaging (fMRI) is very effective method for functional brain mapping but have high costs and limited spatial resolution. Optical imaging of intrinsic signal (IOS) does not provide the required sensitivity, and voltage-sensitive dye optical imaging (VSDi) has limited applicability due to significant toxicity of the voltage-sensitive dye. Our planar solid-state oxygen sensor imaging approach circumvents these limitations, providing a simple optical contrast agent with low toxicity and rapid application. The planar solid-state oxygen sensor described here can be used as a tool in visualization and real-time analysis of sensory-evoked neural activity in vivo. Further, this approach allows visualization of local neural activity with high temporal and spatial resolution. Copyright © 2017 Elsevier B.V. All rights reserved.

Holographic optical assembly and photopolymerized joining of planar microspheres

DOE PAGES

Shaw, L. A.; Chizari, S.; Panas, R. M.; ...

2016-07-27

The aim of this research is to demonstrate a holographically driven photopolymerization process for joining colloidal particles to create planar microstructures fixed to a substrate, which can be monitored with real-time measurement. Holographic optical tweezers (HOT) have been used to arrange arrays of microparticles prior to this work; here we introduce a new photopolymerization process for rapidly joining simultaneously handled microspheres in a plane. Additionally, we demonstrate a new process control technique for efficiently identifying when particles have been successfully joined by measuring a sufficient reduction in the particles’ Brownian motion. Furthermore, this technique and our demonstrated joining approach enablemore » HOT technology to take critical steps toward automated additive fabrication of microstructures.« less

Two solvable problems of planar geometrical optics.

PubMed

Borghero, Francesco; Bozis, George

2006-12-01

In the framework of geometrical optics we consider a two-dimensional transparent inhomogeneous isotropic medium (dispersive or not). We show that (i) for any family belonging to a certain class of planar monoparametric families of monochromatic light rays given in the form f(x,y)=c of any definite color and satisfying a differential condition, all the refractive index profiles n=n(x,y) allowing for the creation of the given family can be found analytically (inverse problem) and that (ii) for any member of a class of two-dimensional refractive index profiles n=n(x,y) satisfying a differential condition, all the compatible families of light rays can be found analytically (direct problem). We present appropriate examples.

Optical waveguides in Nd:GdVO4 crystals fabricated by swift N3+ ion irradiation

NASA Astrophysics Data System (ADS)

Dong, Ningning; Yao, Yicun; Chen, Feng

2012-12-01

Optical planar waveguides have been manufactured in Nd:GdVO4 crystal by swift N3+ ions irradiation at fluence of 1.5 × 1014 ions/cm2. A typical "barrier"-style refractive index profile was formed and the light can be well confined in the waveguide region. The modal distribution of the guided modes obtained from numerical calculation has a good agreement with the experimental modal distribution. The measured photoluminescence spectra revealed that the fluorescence properties of the Nd3+ ions have been modified to some extent in the waveguide's volume. The propagation loss of the planar waveguide can decrease to lower than 1 dB/cm after adequate annealing.

Electro-optical backplane demonstrator with integrated multimode gradient-index thin glass waveguide panel

NASA Astrophysics Data System (ADS)

Schröder, Henning; Brusberg, Lars; Pitwon, Richard; Whalley, Simon; Wang, Kai; Miller, Allen; Herbst, Christian; Weber, Daniel; Lang, Klaus-Dieter

2015-03-01

Optical interconnects for data transmission at board level offer increased energy efficiency, system density, and bandwidth scalability compared to purely copper driven systems. We present recent results on manufacturing of electrooptical printed circuit board (PCB) with integrated planar glass waveguides. The graded index multi-mode waveguides are patterned inside commercially available thin-glass panels by performing a specific ion-exchange process. The glass waveguide panel is embedded within the layer stack-up of a PCB using proven industrial processes. This paper describes the design, manufacture, assembly and characterization of the first electro-optical backplane demonstrator based on integrated planar glass waveguides. The electro-optical backplane in question is created by laminating the glass waveguide panel into a conventional multi-layer electronic printed circuit board stack-up. High precision ferrule mounts are automatically assembled, which will enable MT compliant connectors to be plugged accurately to the embedded waveguide interfaces on the glass panel edges. The demonstration platform comprises a standardized sub-rack chassis and five pluggable test cards each housing optical engines and pluggable optical connectors. The test cards support a variety of different data interfaces and can support data rates of up to 32 Gb/s per channel.

Enhanced sensitivity for optical loss measurement in planar thin-films (Conference Presentation)

NASA Astrophysics Data System (ADS)

Yuan, Hua-Kang

2016-09-01

An organic-inorganic hybrid material benefits from processing advantages of organics and high refractive indices of inorganics. We focus on a titanium oxide hydrate system combined with common bulk polymers. In particular, we target thin-film structures of a few microns in thickness. Traditional Beer-Lambert approaches for measuring optical losses can only provide an upper limit estimate. This sensitivity is highly limited when considering the low-losses required for mid-range optical applications, on the order of 0.1 cm-1. For intensity based measurements, improving the sensitivity requires an increase in the optical path length. Instead, a new sensitive technique suitable for simple planar thin films is required. A number of systems were modelled to measure optical losses in films of 1 micron thick. The presented techniques utilise evanescent waves and total internal reflection to increase optical path length through the material. It was found that a new way of using prism coupling provides the greatest improvement in sensitivity. In keeping the requirements on the material simple, this method for measuring loss is well suited to any future developments of new materials in thin-film structures.

Graphene planar lightwave circuit sensors for chemical detection

NASA Astrophysics Data System (ADS)

Maliakal, Ashok; Husaini, Saima; Reith, Leslie; Bollond, Paul; Cabot, Steve; Sheehan, Paul; Hangartar, Sandra; Walton, Scott; Tamanaha, Cy

2017-02-01

Sensing devices based on Graphene Field Effect Transistors (G-FET) have been demonstrated by several groups to show excellent sensitivity for a variety of chemical agents. These devices are based on measuring changes in the electrical conductivity of graphene when exposed to various chemicals. However, because of its unique band structure, graphene also exhibits changes in its optical response upon chemical exposure. The conical intersection of the valence and conduction bands results in a low density of states near the Dirac point. At this point, chemical doping resulting from molecular binding to graphene can result in dramatic changes in graphene's optical absorption. Here we will discuss our recent work in developing a graphene planar lightwave circuit (PLC) sensor which exploits these optical and electronic properties of graphene to demonstrate chemical sensitivity. The devices are based on a strong evanescent coupling of graphene via electrically gated silicon nanowire waveguides. A strong response in the form of a reversible optical attenuation change of 6 dB is shown when these devices interact with toxic industrial chemicals such as iodine and ammonia. The optical transition can also be tuned to the optical c-band (1530-1565 nm) which enables these devices to operate at telecom wavelengths.

Near-field flat focusing mirrors

NASA Astrophysics Data System (ADS)

Cheng, Yu-Chieh; Staliunas, Kestutis

2018-03-01

This article reviews recent progress towards the design of near-field flat focusing mirrors, focusing/imaging light patterns in reflection. An important feature of such flat focusing mirrors is their transverse invariance, as they do not possess any optical axis. We start with a review of the physical background to the different focusing mechanisms of near- and far-field focusing. These near-field focusing devices like flat lenses and the reviewed near-field focusing mirrors can implement planar focusing devices without any optical axis. In contrast, various types of far-field planar focusing devices, such as high-contrast gratings and metasurfaces, unavoidably break the transverse invariance due to their radially symmetrical structures. The particular realizations of near-field flat focusing mirrors including Bragg-like dielectric mirrors and dielectric subwavelength gratings are the main subjects of the review. The first flat focusing mirror was demonstrated with a chirped mirror and was shown to manage an angular dispersion for beam focusing, similar to the management of chromatic dispersion for pulse compression. Furthermore, the reviewed optimized chirped mirror demonstrated a long near-field focal length, hardly achieved by a flat lens or a planar hyperlens. Two more different configurations of dielectric subwavelength gratings that focus a light beam at normal or oblique incidence are also reviewed. We also summarize and compare focusing performance, limitations, and future perspectives between the reviewed flat focusing mirrors and other planar focusing devices including a flat lens with a negative-index material, a planar hyperlens, a high-contrast grating, and a metasurface.

Thin planar package for cooling an array of edge-emitting laser diodes

DOEpatents

Mundinger, David C.; Benett, William J.

1992-01-01

A laser diode array is disclosed that includes a plurality of planar assemblies and active cooling of each assembly. The laser diode array may be operated in a long duty cycle, or in continuous operation. A laser diode bar and a microchannel heat sink are thermally coupled in a compact, thin planar assembly having the laser diode bar located proximate to one edge. In an array, a number of such thin planar assemblies are secured together in a stacked configuration, in close proximity so that the laser diodes are spaced closely. The cooling means includes a microchannel heat sink proximate to the laser diode bar to absorb heat generated by laser operation. To provide the coolant to the microchannels, each thin planar assembly comprises passageways that connect the microchannels to inlet and outlet corridors. Each inlet passageway may comprise a narrow slot that directs coolant into the microchannels and increases the velocity of flow therethrough. The corridors comprises holes extending through each of the assemblies in the array. The inlet and outlet corridors are connected to a conventional coolant circulation system. The laser diode array with active cooling has applications as an optical pump for high power solid state lasers, or by mating the diodes with fiber optic lenses. Further, the arrays can be useful in applications having space constraints and energy limitations, and in military and space applications. The arrays can be incorporated in equipment such as communications devices and active sensors.

Computer-controlled multi-parameter mapping of 3D compressible flowfields using planar laser-induced iodine fluorescence

NASA Technical Reports Server (NTRS)

Donohue, James M.; Victor, Kenneth G.; Mcdaniel, James C., Jr.

1993-01-01

A computer-controlled technique, using planar laser-induced iodine fluorescence, for measuring complex compressible flowfields is presented. A new laser permits the use of a planar two-line temperature technique so that all parameters can be measured with the laser operated narrowband. Pressure and temperature measurements in a step flowfield show agreement within 10 percent of a CFD model except in regions close to walls. Deviation of near wall temperature measurements from the model was decreased from 21 percent to 12 percent compared to broadband planar temperature measurements. Computer-control of the experiment has been implemented, except for the frequency tuning of the laser. Image data storage and processing has been improved by integrating a workstation into the experimental setup reducing the data reduction time by a factor of 50.

Development of a wavelength tunable filter using MEMS technology

NASA Astrophysics Data System (ADS)

Liu, Junting

Microelectromechanical systems (MEMS) for optical applications have received intensive attention in recent years because of their potential applications in optical telecommunication. Traditional wavelength division multiplexing (WDM) offers high capacity but requires the fabrication of selective add-drop filters. MEMS technology offers an effective way to fabricate these components at low cost. This thesis presents the development of a device that tunes the Bragg wavelength by coupling into the evanescent field of the grating. A Bragg grating is a periodic perturbation of the refractive index along a fiber or a periodic perturbation of the structure of a planar waveguide. The Bragg wavelength can be tuned by changing the degree to which a dielectric slab couples into the evanescent field. The result is a change in the effective index of the grating, and thus a change in the wavelength that which it reflects. In this thesis Bragg gratings were successfully written into an optical fiber using phase mask technique. Mechanical polishing was used to side-polish the fiber and remove cladding to expose the core. Grating structures were also fabricated in planar waveguide using E-beam writing and dry etching. In order to achieve the smoothest possible morphology of the waveguide, plasma dry etching of transparent substrates was studied in great detail. It is found that the pre-etch cleaning procedure greatly influences the ability to obtain a smooth etched surface. Upper limits of evanescent field tuning were investigated by applying different index liquids such as D. I. water and index matching oils or by positioning different dielectric materials such as glass and silicon close to the grating. Planar waveguides were found to be more sensitive to effective index change. Two kinds of computer simulation were carried out to understand the mode profile and to estimate the value of effective index of planar waveguide under "dry" and "wet" conditions. The first one used an average depth of grating approximation. The second explicitly considered the corrugated structure of the waveguide. Results of both simulations were compared with the experimental results in order to find the proper simulation approach. The fiber or planar waveguide gratings were "device" integrated and their pro and cons were compared. Devices using an optical fiber employed a microactuator driven by electrothermal vibromotor to change the degree of coupling between fiber and "tuning block". Device using planar waveguides used an electrostatic force actuated membrane, flip-chip mounted atop the waveguide. All devices were fabricated using polysilicon surface micromachining processes. I concluded that devices driven by electrostatic force were easier to actuate and their integration with waveguide less challenging.

Electromagnetically induced transparency control in terahertz metasurfaces based on bright-bright mode coupling

NASA Astrophysics Data System (ADS)

Yahiaoui, R.; Burrow, J. A.; Mekonen, S. M.; Sarangan, A.; Mathews, J.; Agha, I.; Searles, T. A.

2018-04-01

We demonstrate a classical analog of electromagnetically induced transparency (EIT) in a highly flexible planar terahertz metamaterial (MM) comprised of three-gap split-ring resonators. The keys to achieve EIT in this system are the frequency detuning and hybridization processes between two bright modes coexisting in the same unit cell as opposed to bright-dark modes. We present experimental verification of two bright modes coupling for a terahertz EIT-MM in the context of numerical results and theoretical analysis based on a coupled Lorentz oscillator model. In addition, a hybrid variation of the EIT-MM is proposed and implemented numerically to dynamically tune the EIT window by incorporating photosensitive silicon pads in the split gap region of the resonators. As a result, this hybrid MM enables the active optical control of a transition from the on state (EIT mode) to the off state (dipole mode).

Continuous planar phospholipid bilayer supported on porous silicon thin film reflector.

PubMed

Cunin, Frédérique; Milhiet, Pierre-Emmanuel; Anglin, Emily; Sailor, Michael J; Espenel, Cédric; Le Grimellec, Christian; Brunel, Daniel; Devoisselle, Jean-Marie

2007-10-01

Reconstituting artificial membranes for in vitro studies of cell barrier mechanisms and properties is of major interest in biology. Here, artificial membranes supported on porous silicon photonic crystal reflectors are prepared and investigated. The materials are of interest for label-free probing of supported membrane events such as protein binding, molecular recognition, and transport. The porous silicon substrates are prepared as multilayered films consisting of a periodically varying porosity, with pore dimensions of a few nanometers in size. Planar phospholipid bilayers are deposited on the topmost surface of the oxidized hydrophilic mesoporous silicon films. Atomic force microscopy provides evidence of continuous bilayer deposition at the surface, and optical measurements indicate that the lipids do not significantly infiltrate the porous region. The presence of the supported bilayer does not obstruct the optical spectrum from the porous silicon layer, suggesting that the composite structures can act as effective optical biosensors.

Photonic devices on planar and curved substrates and methods for fabrication thereof

DOEpatents

Bartl, Michael H.; Barhoum, Moussa; Riassetto, David

2016-08-02

A versatile and rapid sol-gel technique for the fabrication of high quality one-dimensional photonic bandgap materials. For example, silica/titania multi-layer materials may be fabricated by a sol-gel chemistry route combined with dip-coating onto planar or curved substrate. A shock-cooling step immediately following the thin film heat-treatment process is introduced. This step was found important in the prevention of film crack formation--especially in silica/titania alternating stack materials with a high number of layers. The versatility of this sol-gel method is demonstrated by the fabrication of various Bragg stack-type materials with fine-tuned optical properties by tailoring the number and sequence of alternating layers, the film thickness and the effective refractive index of the deposited thin films. Measured optical properties show good agreement with theoretical simulations confirming the high quality of these sol-gel fabricated optical materials.

Spectral behavior of integrated optics asymmetric y-junction used for optimizing a planar optics telescope beam combiner

NASA Astrophysics Data System (ADS)

Schanen-Duport, Isabelle; Persegol, Dominique; Collomb, Virginie; Minier, Vincent; Haguenauer, Pierre

2017-11-01

Astronomical aperture synthesis requires to combine beams coming from telescopes, with constraints on mechanical and thermal stability, accuracy on the measurement of the interferences visibility. One adapted way for solving the problem is integrated planar optics. A first two telescope beam combiner made by ion exchange technique on glass substrate and build with symmetric Y-junction provides laboratory white light interferograms simultaneously with photometric calibration. In order to increase the interferometric signal without loss of photometric output, we propose to replace symmetric Y-junctions by asymmetric ones. In this paper, we report the conception, the manufacturing and the characterization of asymmetric Y-junction realized by ion exchange on glass substrate. The specific application of astronomical interferometry required the characterization of such component in term of spectral behavior, so we report the simulation and the measurement of asymmetric Y-junction response versus wavelength.

Numerical simulation and optimal design of Segmented Planar Imaging Detector for Electro-Optical Reconnaissance

NASA Astrophysics Data System (ADS)

Chu, Qiuhui; Shen, Yijie; Yuan, Meng; Gong, Mali

2017-12-01

Segmented Planar Imaging Detector for Electro-Optical Reconnaissance (SPIDER) is a cutting-edge electro-optical imaging technology to realize miniaturization and complanation of imaging systems. In this paper, the principle of SPIDER has been numerically demonstrated based on the partially coherent light theory, and a novel concept of adjustable baseline pairing SPIDER system has further been proposed. Based on the results of simulation, it is verified that the imaging quality could be effectively improved by adjusting the Nyquist sampling density, optimizing the baseline pairing method and increasing the spectral channel of demultiplexer. Therefore, an adjustable baseline pairing algorithm is established for further enhancing the image quality, and the optimal design procedure in SPIDER for arbitrary targets is also summarized. The SPIDER system with adjustable baseline pairing method can broaden its application and reduce cost under the same imaging quality.

Luminescent sensing and imaging of oxygen: Fierce competition to the Clark electrode

PubMed Central

2015-01-01

Luminescence‐based sensing schemes for oxygen have experienced a fast growth and are in the process of replacing the Clark electrode in many fields. Unlike electrodes, sensing is not limited to point measurements via fiber optic microsensors, but includes additional features such as planar sensing, imaging, and intracellular assays using nanosized sensor particles. In this essay, I review and discuss the essentials of (i) common solid‐state sensor approaches based on the use of luminescent indicator dyes and host polymers; (ii) fiber optic and planar sensing schemes; (iii) nanoparticle‐based intracellular sensing; and (iv) common spectroscopies. Optical sensors are also capable of multiple simultaneous sensing (such as O2 and temperature). Sensors for O2 are produced nowadays in large quantities in industry. Fields of application include sensing of O2 in plant and animal physiology, in clinical chemistry, in marine sciences, in the chemical industry and in process biotechnology. PMID:26113255

High-power 0.87-micron channel substrate planar lasers for spaceborne communications

NASA Technical Reports Server (NTRS)

Connolly, J. C.; Stewart, T. R.; Gilbert, D. B.; Slavin, S. E.; Carlin, D. B.

1988-01-01

High-power single-mode channeled-substrate planar AlGaAs diode lasers are being developed for reliable high-power operation for use as sources in spaceborne optical communication systems. The CSP laser structure has been optimized for operation at an emission wavelength of 870 nm. Such devices have exhibited output powers in excess of 80 mW CW at an operating temperature of 80 C.

Real-time label-free biosensing with integrated planar waveguide ring resonators

NASA Astrophysics Data System (ADS)

Sohlström, Hans; Gylfason, Kristinn B.; Hill, Daniel

2010-05-01

We review the use of planar integrated optical waveguide ring resonators for label free bio-sensing and present recent results from two European biosensor collaborations: SABIO and InTopSens. Planar waveguide ring resonators are attractive for label-free biosensing due to their small footprint, high Q-factors, and compatibility with on-chip optics and microfluidics. This enables integrated sensor arrays for compact labs-on-chip. One application of label-free sensor arrays is for point-of-care medical diagnostics. Bringing such powerful tools to the single medical practitioner is an important step towards personalized medicine, but requires addressing a number of issues: improving limit of detection, managing the influence of temperature, parallelization of the measurement for higher throughput and on-chip referencing, efficient light-coupling strategies to simplify alignment, and packaging of the optical chip and integration with microfluidics. From the SABIO project we report refractive index measurement and label-free biosensing in an 8-channel slotwaveguide ring resonator sensor array, within a compact cartridge with integrated microfluidics. The sensors show a volume sensing detection limit of 5 x 10-6 RIU and a surface sensing detection limit of 0.9 pg/mm2. From the InTopSens project we report early results on silicon-on-insulator racetrack resonators.

Hybridization of active and passive elements for planar photonic components and interconnects

NASA Astrophysics Data System (ADS)

Pearson, M.; Bidnyk, S.; Balakrishnan, A.

2007-02-01

The deployment of Passive Optical Networks (PON) for Fiber-to-the-Home (FTTH) applications currently represents the fastest growing sector of the telecommunication industry. Traditionally, FTTH transceivers have been manufactured using commodity bulk optics subcomponents, such as thin film filters (TFFs), micro-optic collimating lenses, TO-packaged lasers, and photodetectors. Assembling these subcomponents into a single housing requires active alignment and labor-intensive techniques. Today, the majority of cost reducing strategies using bulk subcomponents has been implemented making future reductions in the price of manufacturing FTTH transceivers unlikely. Future success of large scale deployments of FTTH depends on further cost reductions of transceivers. Realizing the necessity of a radically new packaging approach for assembly of photonic components and interconnects, we designed a novel way of hybridizing active and passive elements into a planar lightwave circuit (PLC) platform. In our approach, all the filtering components were monolithically integrated into the chip using advancements in planar reflective gratings. Subsequently, active components were passively hybridized with the chip using fully-automated high-capacity flip-chip bonders. In this approach, the assembly of the transceiver package required no active alignment and was readily suitable for large-scale production. This paper describes the monolithic integration of filters and hybridization of active components in both silica-on-silicon and silicon-on-insulator PLCs.

New Insight into the Angle Insensitivity of Ultrathin Planar Optical Absorbers for Broadband Solar Energy Harvesting.

PubMed

Liu, Dong; Yu, Haitong; Duan, Yuanyuan; Li, Qiang; Xuan, Yimin

2016-09-01

Two challenging problems still remain for optical absorbers consisting of an ultrathin planar semiconductor film on top of an opaque metallic substrate. One is the angle-insensitive mechanism and the other is the system design needed for broadband solar energy harvesting. Here, first we theoretically demonstrates that the high refractive index, instead of the ultrathin feature as reported in previous studies, is the physical origin of the angle insensitivity for ultrathin planar optical absorbers. They exhibit omnidirectional resonance for TE polarization due to the high complex refractive index difference between the semiconductor and the air, while for TM polarization the angle insensitivity persists up to an incident angle related to the semiconductor refractive index. These findings were validated by fabricating and characterizing an 18 nm Ge/Ag absorber sample (representative of small band gap semiconductors for photovoltaic applications) and a 22 nm hematite/Ag sample (representative of large band gap semiconductors for photoelectrochemical applications). Then, we took advantage of angle insensitivity and designed a spectrum splitting configuration for broadband solar energy harvesting. The cascaded solar cell and unassisted solar water splitting systems have photovoltaic and photoelectrochemical cells that are also spectrum splitters, so an external spectrum splitting element is not needed.

Rotational MEMS mirror with latching arm for silicon photonics

NASA Astrophysics Data System (ADS)

Brière, Jonathan; Beaulieu, Philippe-Olivier; Saidani, Menouer; Nabki, Frederic; Menard, Michaël.

2015-02-01

We present an innovative rotational MEMS mirror that can control the direction of propagation of light beams inside of planar waveguides implemented in silicon photonics. Potential applications include but are not limited to optical telecommunications, medical imaging, scan and spectrometry. The mirror has a half-cylinder shape with a radius of 300 μm that provides low and constant optical losses over the full angular displacement range. A circular comb drive structure is anchored such that it allows free or latched rotation experimentally demonstrated over 8.5° (X-Y planar rotational movement) using 290V electrostatic actuation. The entire MEMS structure was implemented using the MEMSCAP SOIMUMPs process. The center of the anchor beam is designed to be the approximate rotation point of the circular comb drive to counter the rotation offset of the mirror displacement. A mechanical characterization of the MEMS mirror is presented. The latching mechanism provides up to 20 different angular locking positions allowing the mirror to counter any resonance or vibration effects and it is actuated with an electrostatic linear comb drive. An innovative gap closing structure was designed to reduce optical propagation losses due to beam divergence in the interstitial space between the mirror and the planar waveguide. The gap closing structure is also electrostatically actuated and includes two side stoppers to prevent stiction.

SPECIAL ISSUE ON OPTICAL PROCESSING OF INFORMATION: Waveguide optoelectronic components for devices used in functional processing of digital information

NASA Astrophysics Data System (ADS)

Gladkii, V. P.; Nikitin, V. A.; Prokhorov, V. P.; Yakovenko, N. A.

1995-10-01

The results are given of technologic and circuit-engineering development of planar micro-optics components made of glasses and of lithium niobate. These components are intended for devices to be used in logic—arithmetic processing of information.

Efficient Planar Perovskite Solar Cells Using Passivated Tin Oxide as an Electron Transport Layer.

PubMed

Lee, Yonghui; Lee, Seunghwan; Seo, Gabseok; Paek, Sanghyun; Cho, Kyung Taek; Huckaba, Aron J; Calizzi, Marco; Choi, Dong-Won; Park, Jin-Seong; Lee, Dongwook; Lee, Hyo Joong; Asiri, Abdullah M; Nazeeruddin, Mohammad Khaja

2018-06-01

Planar perovskite solar cells using low-temperature atomic layer deposition (ALD) of the SnO 2 electron transporting layer (ETL), with excellent electron extraction and hole-blocking ability, offer significant advantages compared with high-temperature deposition methods. The optical, chemical, and electrical properties of the ALD SnO 2 layer and its influence on the device performance are investigated. It is found that surface passivation of SnO 2 is essential to reduce charge recombination at the perovskite and ETL interface and show that the fabricated planar perovskite solar cells exhibit high reproducibility, stability, and power conversion efficiency of 20%.

Resonance transparency with low-loss in toroidal planar metamaterial

NASA Astrophysics Data System (ADS)

Xiang, Tianyu; Lei, Tao; Hu, Sen; Chen, Jiao; Huang, Xiaojun; Yang, Helin

2018-03-01

A compact planar construction composed of asymmetric split ring resonators was designed with a low-loss, high Q-factor resonance transparency at microwave frequency. The singularity property of the proposed metamaterial owing to the enhanced toroidal dipole T is demonstrated via numerical and experimental methods. The transmission peak can reach up to 0.91 and the loss is perfectly repressed, which can be testified by radiated power, H-field distributions, and the imaginary parts of effective permittivity and permeability. The designed planar metamaterial may have numerous potential applications at microwave, terahertz, and optical frequency, e.g., for ultrasensitive sensing, slow-light devices, lasing spacers, even invisible information transfer.

A pilot study of planar coil based magnetic stimulation using acute hippocampal slice in mice.

PubMed

Park, H J; Kang, H K; Wang, M; Jo, J; Chung, E; Kim, S

2017-07-01

Micromagnetic stimulation using small-sized implantable coils has recently been studied. The main advantage of this method is that it can provide sustainable stimulation performance even if a fibrotic encapsulation layer is formed around the implanted coil by inflammation response, because indirectly induced currents are used to induce neural responses. In previous research, we optimized the geometrical and control parameters used in implantable magnetic stimulation. Based on those results, we fabricated the planar coil and studied the LTP effect in the hippocampal slice by two different magnetic stimulation protocols using the quadripulse stimulation (QPS) pattern. We found that direct magnetic stimulation (DMS) induced insignificant LTP effect and priming magnetic stimulation (PMS) occluded LTP effect after tetanic stimulation, when QPS patterned magnetic stimulation with 1 A current pulse was applied to the planar coil.

Planar laser-induced fluorescence measurements of high-enthalpy free jet flow with nitric oxide

NASA Technical Reports Server (NTRS)

Palmer, Jennifer L.; Mcmillin, Brian K.; Hanson, Ronald K.

1992-01-01

Planar laser-induced fluorescence (PLIF) measurements of property fields in a high-enthalpy, supersonic, underexpanded free jet generated in a reflection-type shock tunnel are reported. PLIF images showing velocity and temperature sensitivity are presented. The inferred radial velocity and relative rotational temperature fields are found to be in agreement with those predicted by a numerical simulation of the flowfield using the method of characteristics.

Focusing properties of x-ray polymer refractive lenses from SU-8 resist layer

NASA Astrophysics Data System (ADS)

Snigirev, Anatoly A.; Snigireva, Irina; Drakopoulos, Michael; Nazmov, Vladimir; Reznikova, Elena; Kuznetsov, Sergey; Grigoriev, Maxim; Mohr, Jurgen; Saile, Volker

2003-12-01

Compound refractive lenses printed in Al and Be are becoming the key X-ray focusing and imaging components of beamline optical layouts at the 3rd generation synchrotron radiation sources. Recently proposed planar optical elements based on Si, diamond etc. may substantially broaden the spectrum of the refractive optics applicability. Planar optics has focal distances ranging from millimeters to tens of meters offering nano- and micro-focusing lenses, as well as beam condensers and collimators. Here we promote deep X-ray lithography and LIGA-type techniques to create high aspect-ratio lens structures for different optical geometries. Planar X-ray refractive lenses were manufactured in 1 mm thick SU-8 negative resist layer by means of deep synchrotron radiation lithography. The focusing properties of lenses were studied at ID18F and BM5 beamlines at the ESRF using monochromatic radiation in the energy range of 10 - 25 keV. By optimizing lens layout, mask making and resist processing, lenses of good quality were fabricated. The resolution of about 270 nm (FWHM) with gain in the order of 300 was measured at 14 keV. In-line holography of B-fiber was realized in imaging and projection mode with a magnification of 3 and 20, respectively. Submicron features of the fiber were clearly resolved. A radiation stability test proved that the fabricated lenses don't change focusing characteristics after dose of absorbed X-ray radiation of about 2 MJ/cm3. The unique radiation stability along with the high effficiency of SU8 lenses opens wide range of their synchrotron radiation applications such as microfocusing elements, condensers and collimators.

Optical MEMS platform for low-cost on-chip integration of planar light circuits and optical switching

NASA Astrophysics Data System (ADS)

German, Kristine A.; Kubby, Joel; Chen, Jingkuang; Diehl, James; Feinberg, Kathleen; Gulvin, Peter; Herko, Larry; Jia, Nancy; Lin, Pinyen; Liu, Xueyuan; Ma, Jun; Meyers, John; Nystrom, Peter; Wang, Yao Rong

2004-07-01

Xerox Corporation has developed a technology platform for on-chip integration of latching MEMS optical waveguide switches and Planar Light Circuit (PLC) components using a Silicon On Insulator (SOI) based process. To illustrate the current state of this new technology platform, working prototypes of a Reconfigurable Optical Add/Drop Multiplexer (ROADM) and a l-router will be presented along with details of the integrated latching MEMS optical switches. On-chip integration of optical switches and PLCs can greatly reduce the size, manufacturing cost and operating cost of multi-component optical equipment. It is anticipated that low-cost, low-overhead optical network products will accelerate the migration of functions and services from high-cost long-haul markets to price sensitive markets, including networks for metropolitan areas and fiber to the home. Compared to the more common silica-on-silicon PLC technology, the high index of refraction of silicon waveguides created in the SOI device layer enables miniaturization of optical components, thereby increasing yield and decreasing cost projections. The latching SOI MEMS switches feature moving waveguides, and are advantaged across multiple attributes relative to alternative switching technologies, such as thermal optical switches and polymer switches. The SOI process employed was jointly developed under the auspice of the NIST APT program in partnership with Coventor, Corning IntelliSense Corp., and MicroScan Systems to enable fabrication of a broad range of free space and guided wave MicroOptoElectroMechanical Systems (MOEMS).

Reflected wavefront manipulation based on ultrathin planar acoustic metasurfaces

PubMed Central

Li, Yong; Liang, Bin; Gu, Zhong-ming; Zou, Xin-ye; Cheng, Jian-chun

2013-01-01

The introduction of metasurfaces has renewed the Snell's law and opened up new degrees of freedom to tailor the optical wavefront at will. Here, we theoretically demonstrate that the generalized Snell's law can be achieved for reflected acoustic waves based on ultrathin planar acoustic metasurfaces. The metasurfaces are constructed with eight units of a solid structure to provide discrete phase shifts covering the full 2π span with steps of π/4 by coiling up the space. By careful selection of the phase profiles in the transverse direction of the metasurfaces, some fascinating wavefront engineering phenomena are demonstrated, such as anomalous reflections, conversion of propagating waves into surface waves, planar aberration-free lens and nondiffracting Bessel beam generated by planar acoustic axicon. Our results could open up a new avenue for acoustic wavefront engineering and manipulations. PMID:23986034

Exact analytic flux distributions for two-dimensional solar concentrators.

PubMed

Fraidenraich, Naum; Henrique de Oliveira Pedrosa Filho, Manoel; Vilela, Olga C; Gordon, Jeffrey M

2013-07-01

A new approach for representing and evaluating the flux density distribution on the absorbers of two-dimensional imaging solar concentrators is presented. The formalism accommodates any realistic solar radiance and concentrator optical error distribution. The solutions obviate the need for raytracing, and are physically transparent. Examples illustrating the method's versatility are presented for parabolic trough mirrors with both planar and tubular absorbers, Fresnel reflectors with tubular absorbers, and V-trough mirrors with planar absorbers.

Planar induction of anteroposterior pattern in the developing central nervous system of Xenopus laevis

NASA Technical Reports Server (NTRS)

Doniach, T.; Phillips, C. R.; Gerhart, J. C.

1992-01-01

It has long been thought that anteroposterior (A-P) pattern in the vertebrate central nervous system is induced in the embryo's dorsal ectoderm exclusively by signals passing vertically from underlying, patterned dorsal mesoderm. Explants from early gastrulae of the frog Xenopus laevis were prepared in which vertical contact between dorsal ectoderm and mesoderm was prevented but planar contact was maintained. In these, four position-specific neural markers (engrailed-2, Krox-20, XlHbox 1, and XlHbox 6) were expressed in the ectoderm in the same A-P order as in the embryo. Thus, planar signals alone, following a path available in the normal embryo, can induce A-P neural pattern.

Integrated optical tamper sensor with planar waveguide

DOEpatents

Carson, Richard F.; Casalnuovo, Stephen A.

1993-01-01

A monolithic optical tamper sensor, comprising an optical emitter and detector, connected by an optical waveguide and placed into the critical entry plane of an enclosed sensitive region, the tamper sensor having a myriad of scraps of a material optically absorbent at the wavelength of interest, such that when the absorbent material is in place on the waveguide, an unique optical signature can be recorded, but when entry is attempted into the enclosed sensitive region, the scraps of absorbent material will be displaced and the optical/electrical signature of the tamper sensor will change and that change can be recorded.

Integrated optical tamper sensor with planar waveguide

DOEpatents

Carson, R.F.; Casalnuovo, S.A.

1993-01-05

A monolithic optical tamper sensor, comprising an optical emitter and detector, connected by an optical waveguide and placed into the critical entry plane of an enclosed sensitive region, the tamper sensor having a myriad of scraps of a material optically absorbent at the wavelength of interest, such that when the absorbent material is in place on the waveguide, an unique optical signature can be recorded, but when entry is attempted into the enclosed sensitive region, the scraps of absorbent material will be displaced and the optical/electrical signature of the tamper sensor will change and that change can be recorded.

Microphotonic devices for compact planar lightwave circuits and sensor systems

NASA Astrophysics Data System (ADS)

Cardenas Gonzalez, Jaime

2005-07-01

Higher levels of integration in planar lightwave circuits and sensor systems can reduce fabrication costs and broaden viable applications for optical network and sensor systems. For example, increased integration and functionality can lead to sensor systems that are compact enough for easy transport, rugged enough for field applications, and sensitive enough even for laboratory applications. On the other hand, more functional and compact planar lightwave circuits can make optical networks components less expensive for the metro and access markets in urban areas and allow penetration of fiber to the home. Thus, there is an important area of opportunity for increased integration to provide low cost, compact solutions in both network components and sensor systems. In this dissertation, a novel splitting structure for microcantilever deflection detection is introduced. The splitting structure is designed so that its splitting ratio is dependent on the vertical position of the microcantilever. With this structure, microcantilevers sensitized to detect different analytes or biological agents can be integrated into an array on a single chip. Additionally, the integration of a depolarizer into the optoelectronic integrated circuit in an interferometric fiber optic gyroscope is presented as a means for cost reduction. The savings come in avoiding labor intensive fiber pigtailing steps by permitting batch fabrication of these components. In particular, this dissertation focuses on the design of the waveguides and polarization rotator, and the impact of imperfect components on the performance of the depolarizer. In the area of planar lightwave circuits, this dissertation presents the development of a fabrication process for single air interface bends (SAIBs). SAIBs can increase integration by reducing the area necessary to make a waveguide bend. Fabrication and measurement of a 45° SAIB with a bend efficiency of 93.4% for TM polarization and 92.7% for TE polarization are presented.

Method and apparatus for determining pressure-induced frequency-shifts in shock-compressed materials

DOEpatents

Moore, David S.; Schmidt, Stephen C.

1985-01-01

A method and an apparatus for conducting coherent anti-Stokes Raman scattering spectroscopy in shock-compressed materials are disclosed. The apparatus includes a sample vessel having an optically transparent wall and an opposing optically reflective wall. Two coherent laser beams, a pump beam and a broadband Stokes beam, are directed through the window and focused on a portion of the sample. In the preferred embodiment, a projectile is fired from a high-pressure gas gun to impact the outside of the reflective wall, generating a planar shock wave which travels through the sample toward the window. The pump and Stokes beams result in the emission from the shock-compressed sample of a coherent anti-Stokes beam, which is emitted toward the approaching reflective wall of the vessel and reflected back through the window. The anti-Stokes beam is folded into a spectrometer for frequency analysis. The results of such analysis are useful for determining chemical and physical phenomena which occur during the shock-compression of the sample.

Assessment of PLIF-Based Heat Release Rate Markers using DNS of Highly Turbulent Premixed Flames

NASA Astrophysics Data System (ADS)

Zhao, Xinyu; Zhang, Peiyu; Wabel, Timothy; Steinberg, Adam; Wang, Haiou; Hawkes, Evatt

2017-11-01

Planar Laser Induced Fluorescence (PLIF) remains the most common measurement tool for describing turbulent flame topologies. However, the interpretation of the images obtained from such experiments can be obscured due to various experimental constraints, such as the finite laser thickness, the application of intensifier, etc. Synthetic-PLIF images are constructed in this study to understand the effects of various experimental reality using direct numerical simulations. Two DNS databases of highly turbulent premixed methane flames are employed, to generate the synthetic PLIF images. The thickness of the laser sheet and optical blur parameters are systematically varied to study their effects on the implied reactive layer thickness, topological correspondence with heat release rates, as well as the resolved scales of the flames. It is found that the optical blur can have a significant influence on the measured layer thickness, and significant discrepancy between the DNS and the synthetic PLIF arises when the laser thickness is approximately twice the size of the reactive layers.

Method and apparatus for determining pressure-induced frequency-shifts in shock-compressed materials

DOEpatents

Moore, D.S.; Schmidt, S.C.

1983-12-16

A method and an apparatus for conducting coherent anti-Stokes Raman scattering spectroscopy in shock-compressed materials are disclosed. The apparatus includes a sample vessel having an optically transparent wall and an opposing optically reflective wall. Two coherent laser beams, a pump beam and a broadband Stokes beam, are directed through the window and focused on a portion of the sample. In the preferred embodiment, a projectile is fired from a high-pressure gas gun to impact the outside of the reflective wall, generating a planar shock wave which travels through the sample toward the window. The pump and Stokes beams result in the emission from the shock-compressed sample of a coherent anti-Stokes beam, which is emitted toward the approaching reflective wall of the vessel and reflected back through the window. The anti-Stokes beam is folded into a spectrometer for frequency analysis. The results of such analysis are useful for determining chemical and physical phenomena which occur during the shock-compression of the sample.

High energy efficient solid state laser sources

NASA Technical Reports Server (NTRS)

Byer, Robert L.

1988-01-01

Recent progress in the development of highly efficient coherent optical sources is reviewed. This work focusses on nonlinear frequency conversion of the highly coherent output of the Non-Planar Ring Laser Oscillators developed earlier in the program, and includes high efficiency second harmonic generation and the operation of optical parametric oscillators for wavelength diversity and tunability.

Optofluidic waveguides: I. Concepts and implementations

PubMed Central

Schmidt, Holger; Hawkins, Aaron R.

2011-01-01

We review recent developments and current status of liquid-core optical waveguides in optofluidics with emphasis on suitability for creating fully planar optofluidic labs-on-a-chip. In this first of two contributions, we give an overview of the different waveguide types that are being considered for effectively combining micro and nanofluidics with integrated optics. The large number of approaches is separated into conventional index-guided waveguides and more recent implementations using wave interference. The underlying principle for waveguiding and the current status are described for each type. We then focus on reviewing recent work on microfabricated liquid-core antiresonant reflecting optical (ARROW) waveguides, including the development of intersecting 2D waveguide networks and optical fluorescence and Raman detection with planar beam geometry. Single molecule detection capability and addition of electrical control for electrokinetic manipulation and analysis of single bioparticles are demonstrated. The demonstrated performance of liquid-core ARROWs is representative of the potential of integrated waveguides for on-chip detection with ultrahigh sensitivity, and points the way towards the next generation of high-performance, low-cost and portable biomedical instruments. PMID:21442048

Response characterization of a fiber optic sensor array with dye-coated planar waveguide for detection of volatile organic compounds.

PubMed

Lee, Jae-Sung; Yoon, Na-Rae; Kang, Byoung-Ho; Lee, Sang-Won; Gopalan, Sai-Anand; Jeong, Hyun-Min; Lee, Seung-Ha; Kwon, Dae-Hyuk; Kang, Shin-Won

2014-07-01

We have developed a multi-array side-polished optical-fiber gas sensor for the detection of volatile organic compound (VOC) gases. The side-polished optical-fiber coupled with a polymer planar waveguide (PWG) provides high sensitivity to alterations in refractive index. The PWG was fabricated by coating a solvatochromic dye with poly(vinylpyrrolidone). To confirm the effectiveness of the sensor, five different sensing membranes were fabricated by coating the side-polished optical-fiber using the solvatochromic dyes Reinhardt's dye, Nile red, 4-aminophthalimide, 4-amino-N-methylphthalimide, and 4-(dimethylamino)cinnamaldehyde, which have different polarities that cause changes in the effective refractive index of the sensing membrane owing to evanescent field coupling. The fabricated gas detection system was tested with five types of VOC gases, namely acetic acid, benzene, dimethylamine, ethanol, and toluene at concentrations of 1, 2,…,10 ppb. Second-regression and principal component analyses showed that the response properties of the proposed VOC gas sensor were linearly shifted bathochromically, and each gas showed different response characteristics.

Optical waveguide loop for planar trapping of blood cells and microspheres

NASA Astrophysics Data System (ADS)

Ahluwalia, Balpreet S.; Hellesø, Olav G.

2013-09-01

The evanescent field from a waveguide can be used to trap and propel a particle. An optical waveguide loop with an intentional gap at the center is used for planar transport and stable trapping of particles. The waveguide acts as a conveyor belt to trap and deliver spheres towards the gap. At the gap, the counter-diverging light fields hold the sphere at a fixed position. Numerical simulation based on the finite element method was performed in three dimensions using a computer cluster. The field distribution and optical forces for rib and strip waveguide designs are compared and discussed. The optical force on a single particle was computed for various positions of the particle in the gap. Simulation predicted stable trapping of particles in the gap. Depending on the gap separation (2-50 μm) a single or multiple spheres and red blood cells were trapped at the gap. Waveguides were made of tantalum pentaoxide material. The waveguides are only 180 nm thick and thus could be integrated with other functions on the chip.

1.5  kW efficient CW Nd:YAG planar waveguide MOPA laser.

PubMed

Wang, Juntao; Wu, Zhenhai; Su, Hua; Zhou, Tangjian; Lei, Jun; Lv, Wenqiang; He, Jing; Xu, Liu; Chen, Yuejian; Wang, Dan; Tong, Lixin; Hu, Hao; Gao, Qingsong; Tang, Chun

2017-08-15

In this Letter, we report a 1064 nm continuous wave Nd:YAG planar waveguide laser with an output power of 1544 W based on the structure of the master oscillator power amplification. A fiber laser is used as the master oscillator, and diode laser arrays are used as the pump source of the waveguide laser amplifier. The dimension of the waveguide is 1  mm (T)×10  mm (W)×60  mm (L), and the dual end oblique pumping is adopted with different angles. After a single-pass amplification, the power is scaled from 323 to 1544 W with the pump power of 2480 W, leading to an optical-to-optical efficiency of 49%. At the maximum output, the beam quality M 2 are measured to be 2.8 and 7.0 in the guided direction and the unguided direction, respectively. To the best of our knowledge, this is the highest output power of a Nd:YAG planar waveguide laser to date.

Novel photon management for thin-film photovoltaics

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

Menon, Rajesh

2016-11-11

The objective of this project is to enable commercially viable thin-film photovoltaics whose efficiencies are increased by over 10% using a novel optical spectral-separation technique. A thin planar diffractive optic is proposed that efficiently separates the solar spectrum and assigns these bands to optimal thin-film sub-cells. An integrated device that is comprised of the optical element, an array of sub-cells and associated packaging is proposed.

Understanding the conductive channel evolution in Na:WO(3-x)-based planar devices.

PubMed

Shang, Dashan; Li, Peining; Wang, Tao; Carria, Egidio; Sun, Jirong; Shen, Baogen; Taubner, Thomas; Valov, Ilia; Waser, Rainer; Wuttig, Matthias

2015-04-14

An ion migration process in a solid electrolyte is important for ion-based functional devices, such as fuel cells, batteries, electrochromics, gas sensors, and resistive switching systems. In this study, a planar sandwich structure is prepared by depositing tungsten oxide (WO(3-x)) films on a soda-lime glass substrate, from which Na(+) diffuses into the WO(3-x) films during the deposition. The entire process of Na(+) migration driven by an alternating electric field is visualized in the Na-doped WO(3-x) films in the form of conductive channel by in situ optical imaging combined with infrared spectroscopy and near-field imaging techniques. A reversible change of geometry between a parabolic and a bar channel is observed with the resistance change of the devices. The peculiar channel evolution is interpreted by a thermal-stress-induced mechanical deformation of the films and an asymmetric Na(+) mobility between the parabolic and the bar channels. These results exemplify a typical ion migration process driven by an alternating electric field in a solid electrolyte with a low ion mobility and are expected to be beneficial to improve the controllability of the ion migration in ion-based functional devices, such as resistive switching devices.

Phase-locked two-line OH planar laser-induced fluorescence thermometry in a pulsating gas turbine model combustor at atmospheric pressure.

PubMed

Giezendanner-Thoben, Robert; Meier, Ulrich; Meier, Wolfgang; Heinze, Johannes; Aigner, Manfred

2005-11-01

Two-line OH planar laser-induced fluorescence (PLIF) thermometry was applied to a swirling CH4/air flame in a gas turbine (GT) model combustor at atmospheric pressure, which exhibited self-excited combustion instability. The potential and limitations of the method are discussed with respect to applications in GT-like flames. A major drawback of using OH as a temperature indicator is that no temperature information can be obtained from regions where OH radicals are missing or present in insufficient concentration. The resulting bias in the average temperature is addressed and quantified for one operating condition by a comparison with results from laser Raman measurements applied in the same flame. Care was taken to minimize saturation effects by decreasing the spectral laser power density to a minimum while keeping an acceptable spatial resolution and signal-to-noise ratio. In order to correct for the influence of laser light attenuation, absorption measurements were performed on a single-shot basis and a correction procedure was applied. The accuracy was determined to 4%-7% depending on the location within the flame and on the temperature level. A GT model combustor with an optical combustion chamber is described, and phase-locked 2D temperature distributions from a pulsating flame are presented. The temperature variations during an oscillation cycle are specified, and the general flame behavior is described. Our main goals are the evaluation of the OH PLIF thermometry and the characterization of a pulsating GT-like flame.

Thin display optical projector

DOEpatents

Veligdan, James T.

1999-01-01

An optical system (20) projects light into a planar optical display (10). The display includes laminated optical waveguides (12) defining an inlet face (14) at one end and an outlet screen (16) at an opposite end. A first mirror (26) collimates light from a light source (18) along a first axis, and distributes the light along a second axis. A second mirror (28) collimates the light from the first mirror along the second axis to illuminate the inlet face and produce an image on the screen.

A Unique, Optically Accessible Flame Tube Facility for Lean Combustor Studies

NASA Technical Reports Server (NTRS)

Hicks, Yolanda R.; Locke, Randy J.; Wey, Chowen C.; Bianco, Jean

1995-01-01

A facility that allows interrogation of combusting flows by advanced diagnostic methods and instrumentation has been developed at the NASA Lewis Research Center. An optically accessible flame tube combustor is described which has high temperature, pressure, and air flow capabilities. The windows in the combustor measure 3.8 cm axially by 5.1 cm radially, providing 67% optical access to the 7.6 cm x 7.6 cm cross section flow chamber. Advanced gas analysis instrumentation is available through a gas chromatography/mass spectrometer system (GC/MS), which has on-line capability for heavy hydrocarbon measurement with resolution to the parts per billion level. The instrumentation allows one to study combusting flows and combustor subcomponents, such as fuel injectors and air swirlers. Planar Laser Induced Fluorescence (PLIF) can measure unstable combustion species, which cannot be obtained with traditional gas sampling. This type of data is especially useful to combustion modellers. The optical access allows measurements to have high spatial and temporal resolution. GC/MS data and PLIF images of OH- are presented from experiments using a lean direct injection (LDI) combustor burning Jet-A fuel at inlet temperatures ranging from 810 K to 866 K, combustor pressures up to 1380 kPa, and equivalence ratios from 0.41 to 0.59.

Enhancement of white light OLED efficiency by combining both internal and external light extraction structures

NASA Astrophysics Data System (ADS)

Kao, I.-Ling; Ku, Chun-Neng; Chen, Yi-Ping; Lin, Ding-Zheng

2012-09-01

We proposed an internal nanostructure with a high reflective index planarization layer to solve the optical loss due to the reflective index mismatch between ITO and glass substrate. In our experiments, we found the electrical property of OLED device was significantly influenced by the internal nanostructures without planarization layer. Moreover, the internal extraction structure (IES) is not necessarily beneficial for light extraction. Therefore, we proposed a new substrate combine both internal and external extraction structure (EES) to extract trapping light. We successfully developed a high refractive index (N 1.7) planarization material with flat surface (RMS roughness < 2 nm), and improved about 70% device efficiency compared to traditional glass substrate.

Design and analysis of optical waveguide elements in planar geometry

NASA Astrophysics Data System (ADS)

Mirkov, Mirko Georgiev

1998-10-01

This dissertation presents the theoretical analysis and practical design considerations for planar optical waveguide devices. The analysis takes into account both transverse dimensions of the waveguides and is based on the supermode theory combined with the resonance method for determination of the propagation constants and field profiles of the supermodes. An improved accuracy has been achieved by including the corrections due to the fields in the corner regions of the waveguides using perturbation theory. The following two classes of devices have been analyzed in detail. Curved rectangular waveguides are a common element in an integrated optics circuit. The theoretical analysis in this work shows that some commonly used approximations for determination of the propagation constants of the quasi-modes of the bent waveguides are not necessary. Specifically the imaginary part of the mode propagation constant, which determines the power loss, is calculated exactly using the resonance method, combined with a two- dimensional optimization routine for determination of the real and the imaginary parts of the propagation constants. Subsequently, the results are corrected for the effects of the fields in the corner regions. The latter corrections have not been previously computed and are shown to be significant. Power splitters are another common element of an integrated optical circuit. A new 'bend-free' splitter is suggested and analyzed. The new splitter design consists of only straight parallel channels, which considerably simplify both the analysis and the fabrication of the device. It is shown that a single design parameter determines the power splitting ratio, which can take any given value. The intrinsic power loss in the proposed splitter is minimal, which makes it an attractive alternative to the conventional Y-splitters. The accurate methods of analysis of planar optical waveguides developed in the present work can easily be applied to other integrated optic devices consisting of rectangular waveguides.

Optical performance of random anti-reflection structured surfaces (rARSS) on spherical lenses

NASA Astrophysics Data System (ADS)

Taylor, Courtney D.

Random anti-reflection structured surfaces (rARSS) have been reported to improve transmittance of optical-grade fused silica planar substrates to values greater than 99%. These textures are fabricated directly on the substrates using reactive-ion/inductively-coupled plasma etching (RIE/ICP) techniques, and often result in transmitted spectra with no measurable interference effects (fringes) for a wide range of wavelengths. The RIE/ICP processes used in the fabrication process to etch the rARSS is anisotropic and thus well suited for planar components. The improvement in spectral transmission has been found to be independent of optical incidence angles for values from 0° to +/-30°. Qualifying and quantifying the rARSS performance on curved substrates, such as convex lenses, is required to optimize the fabrication of the desired AR effect on optical-power elements. In this work, rARSS was fabricated on fused silica plano-convex (PCX) and plano-concave (PCV) lenses using a planar-substrate optimized RIE process to maximize optical transmission in the range from 500 to 1100 nm. An additional set of lenses were etched in a non-optimized ICP process to provide additional comparisons. Results are presented from optical transmission and beam propagation tests (optimized lenses only) of rARSS lenses for both TE and TM incident polarizations at a wavelength of 633 nm and over a 70° full field of view in both singlet and doublet configurations. These results suggest optimization of the fabrication process is not required, mainly due to the wide angle-of-incidence AR tolerance performance of the rARSS lenses. Non-optimized recipe lenses showed low transmission enhancement, and confirmed the need to optimized etch recipes prior to process transfer of PCX/PCV lenses. Beam propagation tests indicated no major beam degradation through the optimized lens elements. Scanning electron microscopy (SEM) images confirmed different structure between optimized and non-optimized samples. SEM images also indicated isotropically-oriented surface structures on both types of lenses.

Diamond deposition using a planar radio frequency inductively coupled plasma

NASA Astrophysics Data System (ADS)

Bozeman, S. P.; Tucker, D. A.; Stoner, B. R.; Glass, J. T.; Hooke, W. M.

1995-06-01

A planar radio frequency inductively coupled plasma has been used to deposit diamond onto scratched silicon. This plasma source has been developed recently for use in large area semiconductor processing and holds promise as a method for scale up of diamond growth reactors. Deposition occurs in an annulus which coincides with the area of most intense optical emission from the plasma. Well-faceted diamond particles are produced when the substrate is immersed in the plasma.

INTEGRATED AND FIBER OPTICS: Electrodiffusion of Cs+ ions into glass from molten CsNO3. Planar waveguides

NASA Astrophysics Data System (ADS)

Galechyan, M. G.; Dianov, Evgenii M.; Lyndin, N. M.; Tishchenko, A. V.

1989-02-01

A new method for electrodiffusion of Cs+ ions from molten CsNO3 into glass was developed. A study was made of the dependences of the parameters of the refractive index profile of planar waveguides on the conditions during diffusion. These waveguides were characterized by low losses (less than 0.2 dB/cm) in a wide spectral range and they were stable under heating to 300 °C.

Magneto-optical visualization of three spatial components of inhomogeneous stray fields

NASA Astrophysics Data System (ADS)

Ivanov, V. E.

2012-08-01

The article deals with the physical principles of magneto-optical visualization (MO) of three spatial components of inhomogeneous stray fields with the help of FeCo metal indicator films in the longitudinal Kerr effect geometry. The inhomogeneous field is created by permanent magnets. Both p- and s-polarization light is used for obtaining MO images with their subsequent summing, subtracting and digitizing. As a result, the MO images and corresponding intensity coordinate dependences reflecting the distributions of the horizontal and vertical magnetization components in pure form have been obtained. Modeling of both the magnetization distribution in the indicator film and the corresponding MO images shows that corresponding to polar sensitivity the intensity is proportional to the normal field component, which permits normal field component mapping. Corresponding to longitudinal sensitivity, the intensity of the MO images reflects the angular distribution of the planar field component. MO images have singular points in which the planar component is zero and their movement under an externally homogeneous planar field permits obtaining of additional information on the two planar components of the field under study. The intensity distribution character in the vicinity of sources and sinks (singular points) remains the same under different orientations of the light incidence plane. The change of incident plane orientation by π/2 alters the distribution pattern in the vicinity of the saddle points.

Planar-type ferromagnetic tunnel junctions fabricated by SPM local oxidation

NASA Astrophysics Data System (ADS)

Tomoda, Y.; Kayashima, S.; Ogino, T.; Motoyama, M.; Takemura, Y.; Shirakashi, J.

Nanometer-scale oxide wires were fabricated by local oxidation nanolithography using scanning probe microscope (SPM). This technique was applied to the fabrication of planar-type Ni/Ni oxide/Ni ferromagnetic tunnel junctions. In order to induce magnetic shape anisotropy, asymmetrical channel structure was patterned by conventional photolithography and wet etching processes. The magnetoresistance (MR) characteristics were clearly shown in the planar-type Ni/Ni oxide/Ni ferromagnetic tunnel junctions. MR ratio of above 100% was obtained at 17 K. This result suggests that the local oxidation nanolithography using SPM is useful for the application to planar-type ferromagnetic tunnel junctions.

Large core plastic planar optical splitter fabricated by 3D printing technology

NASA Astrophysics Data System (ADS)

Prajzler, Václav; Kulha, Pavel; Knietel, Marian; Enser, Herbert

2017-10-01

We report on the design, fabrication and optical properties of large core multimode optical polymer splitter fabricated using fill up core polymer in substrate that was made by 3D printing technology. The splitter was designed by the beam propagation method intended for assembling large core waveguide fibers with 735 μm diameter. Waveguide core layers were made of optically clear liquid adhesive, and Veroclear polymer was used as substrate and cover layers. Measurement of optical losses proved that the insertion optical loss was lower than 6.8 dB in the visible spectrum.

Laser Development for Gravitational-Wave Interferometry in Space

NASA Technical Reports Server (NTRS)

Numata, Kenji; Camp, Jordan

2012-01-01

We are reporting on our development work on laser (master oscillator) and optical amplifier systems for gravitational-wave interferometry in space. Our system is based on the mature, wave-guided optics technologies, which have advantages over bulk, crystal-based, free-space optics. We are investing in a new type of compact, low-noise master oscillator, called the planar-waveguide external cavity diode laser. We made measurements, including those of noise, and performed space-qualification tests.

Book Reviews

NASA Astrophysics Data System (ADS)

Radl, Bruce M.; Donnelly, J. P.; Oliner, Arthur A.

1986-08-01

Laser Beam Scanning: Opto-mechanical devices, systems, and data Storage Optics-Reviewed by Bruce M. Radl; Integrated Optoelectronics-Reviewed by J.P. Donnelly; Planar Circuits for Microwaves and Lightwaves-Reviewed by Arthur A. Oliner;

1990 MTT-S International Microwave Symposium and Exhibition and Microwave and Millimeter-Wave Monolithic IC Symposium, Dallas, TX, May 7-10, 1990, Proceedings

NASA Astrophysics Data System (ADS)

McQuiddy, David N., Jr.; Sokolov, Vladimir

1990-12-01

The present conference discusses microwave filters, lightwave technology for microwave antennas, planar and quasi-planar guides, mixers and VCOs, cavity filters, discontinuity and coupling effects, control circuits, power dividers and phase shifters, microwave ICs, biological effects and medical applications, CAD and modeling for MMICs, directional couplers, MMIC design trends, microwave packaging and manufacturing, monolithic ICs, and solid-state devices and circuits. Also discussed are microwave and mm-wave superconducting technology, MICs for communication systems, the merging of optical and microwave technologies, microwave power transistors, ferrite devices, network measurements, advanced transmission-line structures, FET devices and circuits, field theory of IC discontinuities, active quasi-optical techniques, phased-array techniques and circuits, nonlinear CAD, sub-mm wave devices, and high power devices.

Optical study of Erbium-doped-porous silicon based planar waveguides

NASA Astrophysics Data System (ADS)

Najar, A.; Ajlani, H.; Charrier, J.; Lorrain, N.; Haesaert, S.; Oueslati, M.; Haji, L.

2007-06-01

Planar waveguides were formed from porous silicon layers obtained on P + substrates. These waveguides were then doped by erbium using an electrochemical method. Erbium concentration in the range 2.2-2.5 at% was determined by energy dispersive X-ray (EDX) analysis performed on SEM cross sections. The refractive index of layers was studied before and after doping and thermal treatments. The photoluminescence of Er 3+ ions in the IR range and the decay curve of the 1.53 μm emission peak were studied as a function of the excitation power. The value of excited Er density was equal to 0.07%. Optical loss contributions were analyzed on these waveguides and the losses were equal to 1.1 dB/cm at 1.55 μm after doping.

Planar optics with patterned chiral liquid crystals

NASA Astrophysics Data System (ADS)

Kobashi, Junji; Yoshida, Hiroyuki; Ozaki, Masanori

2016-06-01

Reflective metasurfaces based on metallic and dielectric nanoscatterers have attracted interest owing to their ability to control the phase of light. However, because such nanoscatterers require subwavelength features, the fabrication of elements that operate in the visible range is challenging. Here, we show that chiral liquid crystals with a self-organized helical structure enable metasurface-like, non-specular reflection in the visible region. The phase of light that is Bragg-reflected off the helical structure can be controlled over 0-2π depending on the spatial phase of the helical structure; thus planar elements with arbitrary reflected wavefronts can be created via orientation control. The circular polarization selectivity and external field tunability of Bragg reflection open a wide variety of potential applications for this family of functional devices, from optical isolators to wearable displays.

Influence of pump-field scattering on nonclassical-light generation in a photonic-band-gap nonlinear planar waveguide

NASA Astrophysics Data System (ADS)

Peřina, Jan, Jr.; Sibilia, Concita; Tricca, Daniela; Bertolotti, Mario

2005-04-01

Optical parametric process occurring in a nonlinear planar waveguide can serve as a source of light with nonclassical properties. The properties of the generated fields are substantially modified by scattering of the nonlinearly interacting fields in a photonic-band-gap structure inside the waveguide. A general quantum model of linear operator amplitude corrections to the amplitude mean values and its numerical analysis provide conditions for efficient squeezed-light generation as well as generation of light with sub-Poissonian photon-number statistics. The destructive influence of phase mismatch of the nonlinear interaction can fully be compensated using a suitable photonic-band-gap structure inside the waveguide. Also an increase of the signal-to-noise ratio of the incident optical field can be reached in the waveguide.

Optical planar waveguides in photo-thermal-refractive glasses fabricated by single- or double-energy carbon ion implantation

NASA Astrophysics Data System (ADS)

Wang, Yue; Shen, Xiao-Liang; Zheng, Rui-Lin; Guo, Hai-Tao; Lv, Peng; Liu, Chun-Xiao

2018-01-01

Ion implantation has demonstrated to be an efficient and reliable technique for the fabrication of optical waveguides in a diversity of transparent materials. Photo-thermal-refractive glass (PTR) is considered to be durable and stable holographic recording medium. Optical planar waveguide structures in the PTR glasses were formed, for the first time to our knowledge, by the C3+-ion implantation with single-energy (6.0 MeV) and double-energy (5.5+6.0 MeV), respectively. The process of the carbon ion implantation was simulated by the stopping and range of ions in matter code. The morphologies of the waveguides were recorded by a microscope operating in transmission mode. The guided beam distributions of the waveguides were measured by the end-face coupling technique. Comparing with the single-energy implantation, the double-energy implantation improves the light confinement for the dark-mode spectrum. The guiding properties suggest that the carbon-implanted PTR glass waveguides have potential for the manufacture of photonic devices.

Luminescent sensing and imaging of oxygen: fierce competition to the Clark electrode.

PubMed

Wolfbeis, Otto S

2015-08-01

Luminescence-based sensing schemes for oxygen have experienced a fast growth and are in the process of replacing the Clark electrode in many fields. Unlike electrodes, sensing is not limited to point measurements via fiber optic microsensors, but includes additional features such as planar sensing, imaging, and intracellular assays using nanosized sensor particles. In this essay, I review and discuss the essentials of (i) common solid-state sensor approaches based on the use of luminescent indicator dyes and host polymers; (ii) fiber optic and planar sensing schemes; (iii) nanoparticle-based intracellular sensing; and (iv) common spectroscopies. Optical sensors are also capable of multiple simultaneous sensing (such as O2 and temperature). Sensors for O2 are produced nowadays in large quantities in industry. Fields of application include sensing of O2 in plant and animal physiology, in clinical chemistry, in marine sciences, in the chemical industry and in process biotechnology. © 2015 The Author. Bioessays published by WILEY Periodicals, Inc.

Enhancement of polar anchoring strength in a graphene-nematic suspension and its effect on nematic electro-optic switching

NASA Astrophysics Data System (ADS)

Basu, Rajratan

2017-07-01

A small quantity of monolayer graphene flakes is doped in a nematic liquid crystal (LC), and the effective polar anchoring strength coefficient between the LC and the alignment substrate is found to increase by an order of magnitude. The hexagonal pattern of graphene can interact with the LC's benzene rings via π -π electron stacking, enabling the LC to anchor to the graphene surface homogeneously (i.e., planar anchoring). When the LC cell is filled with the graphene-doped LC, some graphene flakes are preferentially attached to the alignment layer and modify the substrate's anchoring property. These spontaneously deposited graphene flakes promote planar anchoring at the substrate and the polar anchoring energy at alignment layer is enhanced significantly. The enhanced anchoring energy is found to impact favorably on the electro-optic response of the LC. Additional studies reveal that the nematic electro-optic switching is significantly faster in the LC-graphene hybrid than that of the pure LC.

Planar waveguide solar concentrator with couplers fabricated by laser-induced backside wet etching

NASA Astrophysics Data System (ADS)

Zhang, Nikai

Solar radiation can be converted directly into electricity by using the photovoltaic effect, which represents the principle of operation of solar cells. Currently, most solar cells are made of crystalline silicon and have a conversion efficiency of about 20% or less. Multi-junction solar cells, made of III-V compound semiconductors, can have efficiencies in excess of 40%. The main factor that prohibits such high-efficiency technologies from wider acceptance is the cost. An alternative approach to using large-area expensive solar cells is to employ lower cost optics and concentrate the solar radiation to smaller cell area, which is the basic principle of solar concentrators. In this thesis, we consider a solar concentrator module that consists of a combination of a lens array and a slab waveguide with etched conical holes on one side of the waveguide, which are aligned with the lenslets. Sunlight coming through each of these lenslets is focused on the backside of the waveguide, where a coupling structure (an etched cone) is fabricated. This coupler changes the propagation direction of the incident light in such a way that light is guided through total internal reflection (TIR) within the glass slab and eventually reaches a solar cell, which is properly mounted on the side of the slab. The concept of this concentrated photovoltaic (CPV) system is based on a planar light guide solar concentrator module, proposed earlier by another group. This project builds on the original idea by including the following substantial modifications. The lens array is to be made of solid glass by a mold technology and provided to us by our industrial partner, Libbey, Inc., as opposed to silicone on glass technology, in which the lenses are made out of silicone and sit on a glass substrate. The coupling structures are cone-shaped holes etched directly into the solid glass waveguide, as opposed to coupling structures that are formed by addition of polymeric layer and consequent patterning. The fabrication of the etched holes in the glass is proposed to be based on a self-aligned process using a laser-induced backside etching (LIBWE) method, which is discussed in this project and its feasibility is examined. The role of different parameters to the concentration level and the optical efficiency of the CPV system are studied by simulations in ZEMAX (which is a leading optical analysis/design software) using non-sequential ray tracing. The optical efficiency of this design under different light concentration level is studied and discussed. The main contributions of this research consist of a new design of a waveguide-based CPV system which can be made entirely of glass by a low-cost glass fabrication method, and a feasibility study in terms of critical fabrication steps and optical performance.

High energy efficient solid state laser sources

NASA Technical Reports Server (NTRS)

Byer, Robert L.

1989-01-01

Recent progress in the development of highly efficient coherent optical sources was reviewed. This work has focused on nonlinear frequency conversion of the highly coherent output of the non-planar ring laser oscillators developed earlier in the program, and includes high efficiency second harmonic generation and the operation of optical parametric oscillators for wavelength diversity and tunability.

Optical integrator for optical dark-soliton detection and pulse shaping.

PubMed

Ngo, Nam Quoc

2006-09-10

The design and analysis of an Nth-order optical integrator using the digital filter technique is presented. The optical integrator is synthesized using planar-waveguide technology. It is shown that a first-order optical integrator can be used as an optical dark-soliton detector by converting an optical dark-soliton pulse into an optical bell-shaped pulse for ease of detection. The optical integrators can generate an optical step function, staircase function, and paraboliclike functions from input optical Gaussian pulses. The optical integrators may be potentially used as basic building blocks of all-optical signal processing systems because the time integrals of signals may sometimes be required for further use or analysis. Furthermore, an optical integrator may be used for the shaping of optical pulses or in an optical feedback control system.

Understanding the conductive channel evolution in Na:WO3-x-based planar devices

NASA Astrophysics Data System (ADS)

Shang, Dashan; Li, Peining; Wang, Tao; Carria, Egidio; Sun, Jirong; Shen, Baogen; Taubner, Thomas; Valov, Ilia; Waser, Rainer; Wuttig, Matthias

2015-03-01

An ion migration process in a solid electrolyte is important for ion-based functional devices, such as fuel cells, batteries, electrochromics, gas sensors, and resistive switching systems. In this study, a planar sandwich structure is prepared by depositing tungsten oxide (WO3-x) films on a soda-lime glass substrate, from which Na+ diffuses into the WO3-x films during the deposition. The entire process of Na+ migration driven by an alternating electric field is visualized in the Na-doped WO3-x films in the form of conductive channel by in situ optical imaging combined with infrared spectroscopy and near-field imaging techniques. A reversible change of geometry between a parabolic and a bar channel is observed with the resistance change of the devices. The peculiar channel evolution is interpreted by a thermal-stress-induced mechanical deformation of the films and an asymmetric Na+ mobility between the parabolic and the bar channels. These results exemplify a typical ion migration process driven by an alternating electric field in a solid electrolyte with a low ion mobility and are expected to be beneficial to improve the controllability of the ion migration in ion-based functional devices, such as resistive switching devices.An ion migration process in a solid electrolyte is important for ion-based functional devices, such as fuel cells, batteries, electrochromics, gas sensors, and resistive switching systems. In this study, a planar sandwich structure is prepared by depositing tungsten oxide (WO3-x) films on a soda-lime glass substrate, from which Na+ diffuses into the WO3-x films during the deposition. The entire process of Na+ migration driven by an alternating electric field is visualized in the Na-doped WO3-x films in the form of conductive channel by in situ optical imaging combined with infrared spectroscopy and near-field imaging techniques. A reversible change of geometry between a parabolic and a bar channel is observed with the resistance change of the devices. The peculiar channel evolution is interpreted by a thermal-stress-induced mechanical deformation of the films and an asymmetric Na+ mobility between the parabolic and the bar channels. These results exemplify a typical ion migration process driven by an alternating electric field in a solid electrolyte with a low ion mobility and are expected to be beneficial to improve the controllability of the ion migration in ion-based functional devices, such as resistive switching devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07545e

Growth of defect-free GaAsSbN axial nanowires via self-catalyzed molecular beam epitaxy

NASA Astrophysics Data System (ADS)

Sharma, Manish; Deshmukh, Prithviraj; Kasanaboina, Pavan; Reynolds, C. Lewis, Jr.; Liu, Yang; Iyer, Shanthi

2017-12-01

Bandgap reduction of 10% by incorporation of a dilute amount of N is reported for the first time, in axial GaAsSb nanowires (NWs) grown on Si (111) via Ga-assisted molecular beam epitaxy. Impact of N incorporation on the surface morphology, NW growth kinetics, and their structural and optical properties were examined. Dilute nitride NWs with Sb composition of 7 at% did not exhibit any noticeable planar defects, as revealed by the absence of satellite twin peaks in the selected-area diffraction pattern and high-resolution transmission electron microscopy imaging. Point defects were also minimal in as-grown dilute nitride NWs, as ascertained from the comparison of low-temperature photoluminescence spectra as well as the shape and shift of Raman modes, with in situ annealed NWs in different ambients. Evidence of enhanced incorporation of N was found in the NWs in situ annealed in N ambient, but with deteriorated optical quality due to simultaneous creation of N-induced defects. The lack of any noticeable defects in the as-grown GaAsSbN NWs demonstrates the advantage of the vapor-liquid-solid mechanism responsible for growth of axial configuration over the vapor-solid growth mechanism for core-shell NWs as well as their thin film counterpart, which commonly exhibit N-induced point defects.

Investigation of optical fibers for gas-phase, ultraviolet laser-induced-fluorescence (UV-LIF) spectroscopy.

PubMed

Hsu, Paul S; Kulatilaka, Waruna D; Jiang, Naibo; Gord, James R; Roy, Sukesh

2012-06-20

We investigate the feasibility of transmitting high-power, ultraviolet (UV) laser pulses through long optical fibers for laser-induced-fluorescence (LIF) spectroscopy of the hydroxyl radical (OH) and nitric oxide (NO) in reacting and non-reacting flows. The fundamental transmission characteristics of nanosecond (ns)-duration laser pulses are studied at wavelengths of 283 nm (OH excitation) and 226 nm (NO excitation) for state-of-the-art, commercial UV-grade fibers. It is verified experimentally that selected fibers are capable of transmitting sufficient UV pulse energy for single-laser-shot LIF measurements. The homogeneous output-beam profile resulting from propagation through a long multimode fiber is ideal for two-dimensional planar-LIF (PLIF) imaging. A fiber-coupled UV-LIF system employing a 6 m long launch fiber is developed for probing OH and NO. Single-laser-shot OH- and NO-PLIF images are obtained in a premixed flame and in a room-temperature NO-seeded N(2) jet, respectively. Effects on LIF excitation lineshapes resulting from delivering intense UV laser pulses through long fibers are also investigated. Proof-of-concept measurements demonstrated in the current work show significant promise for fiber-coupled UV-LIF spectroscopy in harsh diagnostic environments such as gas-turbine test beds.

Compensation of shear waves in photoacoustic tomography with layered acoustic media.

PubMed

Schoonover, Robert W; Anastasio, Mark A

2011-10-01

An image reconstruction formula is presented for photoacoustic computed tomography that accounts for conversion between longitudinal and shear waves in a planar-layered acoustic medium. We assume the optical absorber that produces the photoacoustic wave field is embedded in a single fluid layer and any elastic solid layers present are separated by one or more fluid layers. The measurement aperture is assumed to be planar. Computer simulation studies are conducted to demonstrate and investigate the proposed reconstruction formula.

Designer Disordered Complex Media: Hyperuniform Photonic and Phononic Band Gap Materials

NASA Astrophysics Data System (ADS)

Amoah, Timothy

In this thesis we investigate designer disordered complex media for photonics and phononics applications. Initially we focus on the photonic properties and we analyse hyperuniform disordered structures (HUDS) using numerical simulations. Photonic HUDS are a new class of photonic solids, which display large, isotropic photonic band gaps (PBG) comparable in size to the ones found in photonic crystals (PC). We review their complex interference properties, including the origin of PBGs and potential applications. HUDS combine advantages of both isotropy due to disorder (absence of long-range order) and controlled scattering properties from uniform local topology due to hyperuniformity (constrained disorder). The existence of large band gaps in HUDS contradicts the longstanding intuition that Bragg scattering and long-range translational order is required in PBG formation, and demonstrates that interactions between Mie-like local resonances and multiple scattering can induce on their own PBGs. The discussion is extended to finite height effects of planar architectures such as pseudo-band-gaps in photonic slabs as well as the vertical confinement in the presence of disorder. The particular case of a silicon-on-insulator compatible hyperuniform disordered network structure is considered for TE polarised light. We address technologically realisable designs of HUDS including localisation of light in point-defect-like optical cavities and the guiding of light in freeform PC waveguide analogues. Using finite-difference time domain and band structure computer simulations, we show that it is possible to construct optical cavities in planar hyperuniform disordered solids with isotropic band gaps that effciently confine TE polarised radiation. We thus demonstrate that HUDS are a promising general-purpose design platform for integrated optical micro-circuitry. After analysing HUDS for photonic applications we investigate them in the context of elastic waves towards phononics applications. We demonstrate the first phononic band gaps (PnBG) for HUDS. We find that PnBGs in phononic HUDS can confine and guide elastic waves similar to photonic HUDS for EM radiation.

Advanced Optical Diagnostic Methods for Describing Fuel Injection and Combustion Flowfield Phenomena

NASA Technical Reports Server (NTRS)

Locke, Randy J.; Hicks, Yolanda R.; Anderson, Robert C.

2004-01-01

Over the past decade advanced optical diagnostic techniques have evolved and matured to a point where they are now widely applied in the interrogation of high pressure combusting flows. At NASA Glenn Research Center (GRC), imaging techniques have been used successfully in on-going work to develop the next generation of commercial aircraft gas turbine combustors. This work has centered on providing a means by which researchers and designers can obtain direct visual observation and measurements of the fuel injection/mixing/combustion processes and combustor flowfield in two- and three-dimensional views at actual operational conditions. Obtaining a thorough understanding of the chemical and physical processes at the extreme operating conditions of the next generation of combustors is critical to reducing emissions and increasing fuel efficiency. To accomplish this and other tasks, the diagnostic team at GRC has designed and constructed optically accessible, high pressurer high temperature flame tubes and sectar rigs capable of optically probing the 20-60 atm flowfields of these aero-combustors. Among the techniques employed at GRC are planar laser-induced fluorescence (PLIF) for imaging molecular species as well as liquid and gaseous fuel; planar light scattering (PLS) for imaging fuel sprays and droplets; and spontaneous Raman scattering for species and temperature measurement. Using these techniques, optical measurements never before possible have been made in the actual environments of liquid fueled gas turbines. 2-D mapping of such parameters as species (e.g. OH-, NO and kerosene-based jet fuel) distribution, injector spray angle, and fuel/air distribution are just some of the measurements that are now routinely made. Optical imaging has also provided prompt feedback to researchers regarding the effects of changes in the fuel injector configuration on both combustor performance and flowfield character. Several injector design modifications and improvements have resulted from this feedback. Alternate diagnostic methods are constantly being evaluated as to their suitability as a diagnostic tool in these environments. A new method currently under examination is background oriented Schlieren (BOS) for examining the fuel/air mixing processes. While ratioing the Stokes and anti-Stokes nitrogen lines obtained from spontaneous Raman is being refined for temperature measurement. While the primary focus of the GRC diagnostic work remains optical species measurement and flow stream characterization, an increased emphasis has been placed on our involvement in flame code validation efforts. A functional combustor code should shorten and streamline future combustor design. Quantitative measurements of flow parameters such as temperature, species concentration, drop size and velocity using such methods as Raman and phase Doppler anemometry will provide data necessary in this effort.

Injectant mole-fraction imaging in compressible mixing flows using planar laser-induced iodine fluorescence

NASA Technical Reports Server (NTRS)

Hartfield, Roy J., Jr.; Abbitt, John D., III; Mcdaniel, James C.

1989-01-01

A technique is described for imaging the injectant mole-fraction distribution in nonreacting compressible mixing flow fields. Planar fluorescence from iodine, seeded into air, is induced by a broadband argon-ion laser and collected using an intensified charge-injection-device array camera. The technique eliminates the thermodynamic dependence of the iodine fluorescence in the compressible flow field by taking the ratio of two images collected with identical thermodynamic flow conditions but different iodine seeding conditions.

Highly-dispersive electromagnetic induced transparency in planar symmetric metamaterials.

PubMed

Lu, Xiqun; Shi, Jinhui; Liu, Ran; Guan, Chunying

2012-07-30

We propose, design and experimentally demonstrate highly-dispersive electromagnetically induced transparency (EIT) in planar symmetric metamaterials actively switched and controlled by angles of incidence. Full-wave simulation and measurement results show EIT phenomena, trapped-mode excitations and the associated local field enhancement of two symmetric metamaterials consisting of symmetrically split rings (SSR) and a fishscale (FS) metamaterial pattern, respectively, strongly depend on angles of incidence. The FS metamaterial shows much broader spectral splitting than the SSR metamaterial due to the surface current distribution variation.

Low- and high-index sol-gel films for planar and channel-doped waveguides

NASA Astrophysics Data System (ADS)

Canva, Michael; Chaput, Frederic; Lahlil, Khalid; Rachet, Vincent; Goudket, Helene; Boilot, Jean-Pierre; Levy, Yves

2001-11-01

In view of realizing integrated optic components based on effects such as electro-optic, chi(2):chi(2) cascading, stimulated emission,... one has to first synthesize materials with the proper functionality; this may be achieved by doping solid state matrices by the appropriate organic chromophores. Second, and as important, these materials have to be properly structured into the final optical guiding structures. We shall report on issues related to the realization of chromophore-doped planar waveguides as well as channel waveguides. These structures were realized by either photo-transformation such as photo- chromism and photo-bleaching or reactive ion etching technique, starting with chromophore doped sol-gel materials at high loading contents for which optical index may be controlled via the local dopant concentration. With these materials and techniques, waveguides and components characterized by propagation losses of the order of a cm-1, measured off the edge of the absorption band of the doping species, were fabricated. In order to be also able to study and use waveguide functionalized with low concentration of chromophore species, we developed new sol-gel materials of high optical index, yet low temperature processed. These new films are under study to evaluate their potential as host for organic doped waveguides devices.

A rigid and thermally stable all ceramic optical support bench assembly for the LSST Camera

NASA Astrophysics Data System (ADS)

Kroedel, Matthias; Langton, J. Brian; Wahl, Bill

2017-09-01

This paper will present the ceramic design, fabrication and metrology results and assembly plan of the LSST camera optical bench structure which is using the unique manufacturing features of the HB-Cesic technology. The optical bench assembly consists of a rigid "Grid" fabrication supporting individual raft plates mounting sensor assemblies by way of a rigid kinematic support system to meet extreme stringent requirements for focal plane planarity and stability.

Optical Fiber Sensing Using Quantum Dots

PubMed Central

Jorge, Pedro; Martins, Manuel António; Trindade, Tito; Santos, José Luís; Farahi, Faramarz

2007-01-01

Recent advances in the application of semiconductor nanocrystals, or quantum dots, as biochemical sensors are reviewed. Quantum dots have unique optical properties that make them promising alternatives to traditional dyes in many luminescence based bioanalytical techniques. An overview of the more relevant progresses in the application of quantum dots as biochemical probes is addressed. Special focus will be given to configurations where the sensing dots are incorporated in solid membranes and immobilized in optical fibers or planar waveguide platforms. PMID:28903308

Functionalization of optical nanotip arrays with an electrochemical microcantilever for multiplexed DNA detection.

PubMed

Descamps, Emeline; Duroure, Nathalie; Deiss, Frédérique; Leichlé, Thierry; Adam, Catherine; Mailley, Pascal; Aït-Ikhlef, Ali; Livache, Thierry; Nicu, Liviu; Sojic, Neso

2013-08-07

Optical nanotip arrays fabricated on etched fiber bundles were functionalized with DNA spots. Such unconventional substrates (3D and non-planar) are difficult to pattern with standard microfabrication techniques but, using an electrochemical cantilever, up to 400 spots were electrodeposited on the nanostructured optical surface in 5 min. This approach allows each spot to be addressed individually and multiplexed fluorescence detection is demonstrated. Finally, remote fluorescence detection was performed by imaging through the optical fiber bundle itself after hybridisation with the complementary sequence.

Enhanced optical properties of Si nanocrystals in planar microcavity

NASA Astrophysics Data System (ADS)

Toshikiyo, Kimiaki; Fujii, Minoru; Hayashi, Shinji

2003-04-01

The emission property of Si nanocrystals (nc-Si) in an optical microcavity was studied by photoluminescence (PL) and time resolved PL measurements. The PL from the microcavity was narrowed to the line width of 17 meV, enhanced by a factor of 20 compared to the same film without microcavity. The lifetime for nc-Si became shorter by putting the film in microcavity. This results could be well-explained by the redistribution of the optical modes in the cavity due to the presence of the optical resonator.

Electro-optic architecture for servicing sensors and actuators in advanced aircraft propulsion systems

NASA Technical Reports Server (NTRS)

Poppel, G. L.; Glasheen, W. M.

1989-01-01

A detailed design of a fiber optic propulsion control system, integrating favored sensors and electro-optics architecture is presented. Layouts, schematics, and sensor lists describe an advanced fighter engine system model. Components and attributes of candidate fiber optic sensors are identified, and evaluation criteria are used in a trade study resulting in favored sensors for each measurand. System architectural ground rules were applied to accomplish an electro-optics architecture for the favored sensors. A key result was a considerable reduction in signal conductors. Drawings, schematics, specifications, and printed circuit board layouts describe the detailed system design, including application of a planar optical waveguide interface.

Nonlinear Optical Properties of Bacteriorhodopsin and Retinal Chromophores and Their Applications for Optical Information Storage and Processing.

NASA Astrophysics Data System (ADS)

Chen, Zhongping

Retinal, a conjugated polyene, plays a crucial role in biology. Both the visual pigments and the energy transducing protein, bacteriorhodopsin (BR) have a form of retinal as their chromophores. Because visual excitation and energy transduction in these systems is initiated by the promotion of retinal to an excited electronic state, information about the excited-state structure of retinal and the effect of chromophore/protein interactions on this structure are essential to understanding the functions of these systems. In this thesis, surface second harmonic (SH) generation is used to measure the light-induced dipole moment changes of a series of retinal derivatives that were designed and synthesized to model specific components of chromophore/protein interactions. In addition, we report an in situ probe of the dipole moment change of the retinal chromophore bound in BR by SH generation from oriented purple membranes. The dipole moment changes of various forms of BR, including light-adapted, dark-adapted, blue, and acid purple membrane, were measured and compared. These results, combined with the results from model compounds, elucidate the effects of the chromophore/protein interactions on light-induced charge redistribution and give insight on the fundamental nature of light excitation and energy storage in SR and rhodopsin. Furthermore, the dependence of the molecular hyperpolarizability of the conjugated molecules on donor/acceptor strength, protonation, conjugate length, planarity, and nonconjugate charges is investigated. Our study shows for the first time that nonconjugated charges have a very large effect on the nonlinear optical properties of conjugated molecules. BR has interesting photochromic characteristics, very large optical nonlinearities, and a unique optoelectrical property where the polarity of the photovoltage depends on both its photochromic state and the excitation wavelength. These unique characteristics coupled with its high stability make BR an important biological material for optical information processing and storage. Erasable optical storage with three-dimensional capacity and optical implementation of neural networks using SR are reported in this thesis. Oriented BR-polymer films with excellent optical qualities and stable photochromic states are developed, and nondestructive reading of stored information using SH generation is proposed and demonstrated.

High-speed electro-optic polymers: mm-Wave applications and silica planar lightwave circuit integration

NASA Astrophysics Data System (ADS)

Chang, Daniel H.

The development of high speed polymer electro-optic modulators has seen steady and significant progress in recent years, enabling novel applications in RF-Photonics. Two of these are described in this Thesis: an Opto-Electronic Oscillator (OEO), which is a hybrid RF and optical oscillator capable of high spectral purity, and Photonic Time-Stretch, which is a signal processing technique for waveform spectral shifting with application to photonically-assisted A/D conversion. In both cases, the operating frequencies achieved have been the highest demonstrated to date. Application of this promising material to more complicated devices, however, is stymied by insertion loss performance. Current loss figures, while acceptable for single modulators, are too high for large arrays of modulators or intrinsically long devices such as AWGs or photonic-RF phase shifters. This is especially frustrating in light of a key virtue which polymers possess as a photonic material: its photolithographic process-ability makes patterning complex devices possible. Indeed, the current ascendancy of silica-based waveguide devices can be attributed largely to the same reason. In this Thesis, we also demonstrate the first hybrid device composed of silica planar lightwave circuits (PLCs) and polymer planar waveguides. Our approach utilizes grayscale lithography to enable vertical coupling between polymer and silica layers, minimizing entanglement of their respective fabrication processes. We have achieved coupling excess loss figures on the order of 1dB. We believe this is the natural next step in the development of electro-optic polymer devices. The two technologies are highly complementary. Silica PLCs, with excellent propagation loss and fiber coupling, are ideally suited for long passive waveguiding. By endowing them with the high-speed phase shifting capability offered by polymers, active wideband photonic devices of increasing complexity and array size can be contemplated.

Reduced cytotoxicity in PCB-exposed Chinese Hamster Ovary (CHO) cells pretreated with vitamin E.

PubMed

Murati, Teuta; Šimić, Branimir; Pleadin, Jelka; Vukmirović, Maja; Miletić, Marina; Durgo, Ksenija; Kniewald, Jasna; Kmetič, Ivana

2017-01-01

The aim of this study was to evaluate protective effects of vitamin E (50 -150 μM) in ovary cells upon cytotoxic effects induced by two structurally distinct PCB congeners - planar "dioxin-like" PCB 77 and non-planar di-ortho-substituted PCB 153 with an emphasis on identifying differences in the mechanism of vitamin E action depending on the structure of congeners. Application of three bioassays confirmed that PCBs decrease ovarian cell proliferation with slightly profound effects of PCB 77. PCB - induced ROS production and lipid peroxidation were significant for both congeners with also more noticeable effect for PCB 77. Vitamin E pre-incubation has improved viability of cells, reduced ROS formation and lipid peroxidation induced by PCBs' treatment. Preincubation with vitamin E was more effective when cells where treated with non-planar PCB 153. Altogether, vitamin E action was protective, congener specific and more effective when ovary cells were exposed to ortho-substituted PCB congener. Copyright © 2016 Elsevier Ltd. All rights reserved.

Fast Response and Spontaneous Alignment in Liquid Crystals Doped with 12-Hydroxystearic Acid Gelators.

PubMed

Lin, Hui-Chi; Wang, Chih-Hung; Wang, Jyun-Kai; Tsai, Sheng-Feng

2018-05-07

The spontaneous vertical alignment of liquid crystals (LCs) in gelator (12-hydroxystearic acid)-doped LC cells was studied. Gelator-induced alignment can be used in both positive and negative LC cells. The electro-optical characteristics of the gelator-doped negative LC cell were similar to those of an LC cell that contained a vertically aligned (VA) host. The rise time of the gelator-doped LC cell was two orders of magnitude shorter than that of the VA host LC cell. The experimental results indicate that the gelator-induced vertical alignment of LC molecules occurred not only on the surface of the indium tin oxide (ITO) but also on the homogeneous alignment layer. Various LC alignments (planar, hybrid, multistable hybrid, and vertical alignments) were achieved by modulating the doped gelator concentrations. The multistable characteristic of LCs doped with the gelator is also presented. The alignment by doping with a gelator reduces the manufacturing costs and provides a means of fabricating fast-responding, flexible LC displays using a low-temperature process.

Correlation between structural and opto-electronic characteristics of crystalline Si microhole arrays for photonic light management

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

Sontheimer, Tobias, E-mail: tobias.sontheimer@helmholtz-berlin.de; Schnegg, Alexander; Lips, Klaus

2013-11-07

By employing electron paramagnetic resonance spectroscopy, transmission electron microscopy, and optical measurements, we systematically correlate the structural and optical properties with the deep-level defect characteristics of various tailored periodic Si microhole arrays, which are manufactured in an easily scalable and versatile process on nanoimprinted sol-gel coated glass. While tapered microhole arrays in a structured base layer are characterized by partly nanocrystalline features, poor electronic quality with a defect concentration of 10{sup 17} cm{sup −3} and a high optical sub-band gap absorption, planar polycrystalline Si layers perforated with periodic arrays of tapered microholes are composed of a compact crystalline structure and amore » defect concentration in the low 10{sup 16} cm{sup −3} regime. The low defect concentration is equivalent to the one in planar state-of-the-art solid phase crystallized Si films and correlates with a low optical sub-band gap absorption. By complementing the experimental characterization with 3-dimensional finite element simulations, we provide the basis for a computer-aided approach for the low-cost fabrication of novel high-quality structures on large areas featuring tailored opto-electronic properties.« less

High-efficiency solar-thermophotovoltaic system equipped with a monolithic planar selective absorber/emitter

NASA Astrophysics Data System (ADS)

Shimizu, Makoto; Kohiyama, Asaka; Yugami, Hiroo

2015-01-01

We demonstrate a high-efficiency solar-thermophotovoltaic system (STPV) using a monolithic, planar, and spectrally selective absorber/emitter. A complete STPV system using gallium antimonide (GaSb) cells was designed and fabricated to conduct power generation tests. To produce a high-efficiency STPV, it is important to match the thermal radiation spectrum with the sensitive region of the GaSb cells. Therefore, to reach high temperatures with low incident power, a planar absorber/emitter is incorporated for controlling the thermal radiation spectrum. This multilayer coating consists of thin-film tungsten sandwiched by yttria-stabilized zirconia. The system efficiency is estimated to be 16% when accounting for the optical properties of the fabricated absorber/emitter. Power generation tests using a high-concentration solar simulator show that the absorber/emitter temperature peaks at 1640 K with an incident power density of 45 W/cm2, which can be easily obtained by low-cost optics such as Fresnel lenses. The conversion efficiency became 23%, exceeding the Shockley-Queisser limit for GaSb, with a bandgap of 0.67 eV. Furthermore, a total system efficiency of 8% was obtained with the view factor between the emitter and the cell assumed to be 1.

Integration and manufacture of multifunctional planar lightwave circuits

NASA Astrophysics Data System (ADS)

Lipscomb, George F.; Ticknor, Anthony J.; Stiller, Marc A.; Chen, Wenjie; Schroeter, Paul

2001-11-01

The demands of exponentially growing Internet traffic, coupled with the advent of Dense Wavelength Division Multiplexing (DWDM) fiber optic systems to meet those demands, have triggered a revolution in the telecommunications industry. This dramatic change has been built upon, and has driven, improvements in fiber optic component technology. The next generation of systems for the all optical network will require higher performance components coupled with dramatically lower costs. One approach to achieve significantly lower costs per function is to employ Planar Lightwave Circuits (PLC) to integrate multiple optical functions in a single package. PLCs are optical circuits laid out on a silicon wafer, and are made using tools and techniques developed to extremely high levels by the semi-conductor industry. In this way multiple components can be fabricated and interconnected at once, significantly reducing both the manufacturing and the packaging/assembly costs. Currently, the predominant commercial application of PLC technology is arrayed-waveguide gratings (AWG's) for multiplexing and demultiplexing multiple wavelength channels in a DWDM system. Although this is generally perceived as a single-function device, it can be performing the function of more than 100 discrete fiber-optic components and already represents a considerable degree of integration. Furthermore, programmable functions such as variable-optical attenuators (VOAs) and switches made with compatible PLC technology are now moving into commercial production. In this paper, we present results on the integration of active and passive functions together using PLC technology, e.g. a 40 channel AWG multiplexer with 40 individually controllable VOAs.

Optical performance and metallic absorption in nanoplasmonic systems.

PubMed

Arnold, Matthew D; Blaber, Martin G

2009-03-02

Optical metrics relating to metallic absorption in representative plasmonic systems are surveyed, with a view to developing heuristics for optimizing performance over a range of applications. We use the real part of the permittivity as the independent variable; consider strengths of particle resonances, resolving power of planar lenses, and guiding lengths of planar waveguides; and compare nearly-free-electron metals including Al, Cu, Ag, Au, Li, Na, and K. Whilst the imaginary part of metal permittivity has a strong damping effect, field distribution is equally important and thus factors including geometry, real permittivity and frequency must be considered when selecting a metal. Al performs well at low permittivities (e.g. sphere resonances, superlenses) whereas Au & Ag only perform well at very negative permittivities (shell and rod resonances, LRSPP). The alkali metals perform well overall but present engineering challenges.

Planar solar concentrator featuring alignment-free total-internal-reflection collectors and an innovative compound tracker.

PubMed

Teng, Tun-Chien; Lai, Wei-Che

2014-12-15

This study proposed a planar solar concentrator featuring alignment-free total-internal-reflection (TIR) collectors and an innovative compound tracker. The compound tracker, combining a mechanical single-axis tracker and scrollable prism sheets, can achieve a performance on a par with dual-axis tracking while reducing the cost of the tracking system and increasing its robustness. The alignment-free TIR collectors are assembled on the waveguide without requiring alignment, so the planar concentrator is relatively easily manufactured and markedly increases the feasibility for use in large concentrators. Further, the identical TIR collector is applicable to various-sized waveguide slab without requiring modification, which facilitates flexibility regarding the size of the waveguide slab. In the simulation model, the thickness of the slab was 2 mm, and its maximal length reached 6 m. With an average angular tolerance of ±0.6°, and after considering both the Fresnel loss and the angular spread of the sun, the simulation indicates that the waveguide concentrator of a 1000-mm length provides the optical efficiencies of 62-77% at the irradiance concentrations of 387-688, and the one of a 2000-mm length provides the optical efficiencies of 52-64.5% at the irradiance concentrations of 645-1148. Alternatively, if a 100-mm horizontally staggered waveguide slab is collocated with the alignment-free TIR collectors, the optical efficiency would be greatly improved up to 91.5% at an irradiance concentration of 1098 (C(geo) = 1200X).

Planar photovoltaic solar concentrator module

DOEpatents

Chiang, Clement J.

1992-01-01

A planar photovoltaic concentrator module for producing an electrical signal from incident solar radiation includes an electrically insulating housing having a front wall, an opposing back wall and a hollow interior. A solar cell having electrical terminals is positioned within the interior of the housing. A planar conductor is connected with a terminal of the solar cell of the same polarity. A lens forming the front wall of the housing is operable to direct solar radiation incident to the lens into the interior of the housing. A refractive optical element in contact with the solar cell and facing the lens receives the solar radiation directed into the interior of the housing by the lens and directs the solar radiation to the solar cell to cause the solar cell to generate an electrical signal. An electrically conductive planar member is positioned in the housing to rest on the housing back wall in supporting relation with the solar cell terminal of opposite polarity. The planar member is operable to dissipate heat radiated by the solar cell as the solar cell generates an electrical signal and further forms a solar cell conductor connected with the solar cell terminal to permit the electrical signal generated by the solar cell to be measured between the planar member and the conductor.

Planar photovoltaic solar concentrator module

DOEpatents

Chiang, C.J.

1992-12-01

A planar photovoltaic concentrator module for producing an electrical signal from incident solar radiation includes an electrically insulating housing having a front wall, an opposing back wall and a hollow interior. A solar cell having electrical terminals is positioned within the interior of the housing. A planar conductor is connected with a terminal of the solar cell of the same polarity. A lens forming the front wall of the housing is operable to direct solar radiation incident to the lens into the interior of the housing. A refractive optical element in contact with the solar cell and facing the lens receives the solar radiation directed into the interior of the housing by the lens and directs the solar radiation to the solar cell to cause the solar cell to generate an electrical signal. An electrically conductive planar member is positioned in the housing to rest on the housing back wall in supporting relation with the solar cell terminal of opposite polarity. The planar member is operable to dissipate heat radiated by the solar cell as the solar cell generates an electrical signal and further forms a solar cell conductor connected with the solar cell terminal to permit the electrical signal generated by the solar cell to be measured between the planar member and the conductor. 5 figs.

Amplified emission and modified spectral features in an opal hetero-structure mediated by passive defect mode localization

NASA Astrophysics Data System (ADS)

Rout, Dipak; Kumar, Govind; Vijaya, R.

2018-01-01

A photonic crystal hetero-structure consisting of a passive planar defect of SiO2 thin film sandwiched between two identical opals grown by inward growing self-assembly method using Rhodamine-B dye-doped polystyrene microspheres is studied for the characteristics of dye emission. The optical properties and the defect mode characteristics of the hetero-structure are studied from the reflection and transmission measurements. Laser-induced fluorescence from the hetero-structure showed amplified and spectrally narrowed emission compared to the photonic crystal emphasizing the role of the defect mode and distributed feedback. The enhanced emission is also complemented by the reduction in fluorescence decay time in the case of the hetero-structure in comparison to the 3D photonic crystals.

Investigations of a Combustor Using a 9-Point Swirl-Venturi Fuel Injector: Recent Experimental Results

NASA Technical Reports Server (NTRS)

Hicks, Yolanda R.; Heath, Christopher M.; Anderson, Robert C.; Tacina, Kathleen M.

2012-01-01

This paper explores recent results obtained during testing in an optically-accessible, JP8-fueled, flame tube combustor using baseline Lean Direct Injection (LDI) research hardware. The baseline LDI geometry has nine fuel/air mixers arranged in a 3 x 3 array. Results from this nine-element array include images of fuel and OH speciation via Planar Laser-Induced Fluorescence (PLIF), which describe fuel spray pattern and reaction zones. Preliminary combustion temperatures derived from Stokes/Anti-Stokes Spontaneous Raman Spectroscopy are also presented. Other results using chemiluminescence from major combustion radicals such as CH* and C2* serve to identify the primary reaction zone, while OH PLIF shows the extent of reaction further downstream. Air and fuel velocities and fuel drop size results are also reported.

Combined planar imaging of schlieren photography with OH-LIPF and spontaneous OH-emission in a 2-D valveless pulse combustor

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

Ishino, Yojiro; Hasegawa, Tatsuya; Yamaguchi, Shigeki

1999-07-01

Using a novel optical system, simultaneous imaging of schlieren photography and laser induced predissociation fluorescence of OH radicals (OH-LIPF) have been carried out to examine combustion processes and flame structure in a two-dimensional valveless pulse combustor. Simultaneous imaging of schlieren photographs and spontaneous OH-emission have also been made, in order to obtain information on the behavior of the flame front during a cycle of pulsation. The pulse combustor used in this experiment consists of a combustion chamber of a volume of 125 cm{sup 3} and a tailpipe of a length of 976 mm, which is followed by an automobile muffler.more » The fuel used is commercial grade gaseous propane.« less

Method and Apparatus for Creating a Topography at a Surface

DOEpatents

Adams, David P.; Sinclair, Michael B.; Mayer, Thomas M.; Vasile, Michael J.; Sweatt, William C.

2008-11-11

Methods and apparatus whereby an optical interferometer is utilized to monitor and provide feedback control to an integrated energetic particle column, to create desired topographies, including the depth, shape and/or roughness of features, at a surface of a specimen. Energetic particle columns can direct energetic species including, ions, photons and/or neutral particles to a surface to create features having in-plane dimensions on the order of 1 micron, and a height or depth on the order of 1 nanometer. Energetic processes can include subtractive processes such as sputtering, ablation, focused ion beam milling and, additive processes, such as energetic beam induced chemical vapor deposition. The integration of interferometric methods with processing by energetic species offers the ability to create desired topographies at surfaces, including planar and curved shapes.

Seasonal control skylight glazing panel with passive solar energy switching

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

Miller, J.V.

1983-10-25

A substantially transparent one-piece glazing panel is provided for generally horizontal mounting in a skylight. The panel is comprised of an repeated pattern of two alternating and contiguous linear optical elements; a first optical element being an upstanding generally right-triangular linear prism, and the second optical element being an upward-facing plano-cylindrical lens in which the planar surface is reflectively opaque and is generally in the same plane as the base of the triangular prism.

Durable silver thin film coating for diffraction gratings

DOEpatents

Wolfe, Jesse D [Discovery Bay, CA; Britten, Jerald A [Oakley, CA; Komashko, Aleksey M [San Diego, CA

2006-05-30

A durable silver film thin film coated non-planar optical element has been developed to replace Gold as a material for fabricating such devices. Such a coating and resultant optical element has an increased efficiency and is resistant to tarnishing, can be easily stripped and re-deposited without modifying underlying grating structure, improves the throughput and power loading of short pulse compressor designs for ultra-fast laser systems, and can be utilized in variety of optical and spectrophotometric systems, particularly high-end spectrometers that require maximized efficiency.

Grating tuned unstable resonator laser cavity

DOEpatents

Johnson, Larry C.

1982-01-01

An unstable resonator to be used in high power, narrow line CO.sub.2 pump lasers comprises an array of four reflectors in a ring configuration wherein spherical and planar wavefronts are separated from each other along separate optical paths and only the planar wavefronts are impinged on a plane grating for line tuning. The reflector array comprises a concave mirror for reflecting incident spherical waves as plane waves along an output axis to form an output beam. A plane grating on the output axis is oriented to reflect a portion of the output beam off axis onto a planar relay mirror spaced apart from the output axis in proximity to the concave mirror. The relay mirror reflects plane waves from the grating to impinge on a convex expanding mirror spaced apart from the output axis in proximity to the grating. The expanding mirror reflects the incident planar waves as spherical waves to illuminate the concave mirror. Tuning is provided by rotating the plane grating about an axis normal to the output axis.

1.5-μm high-average power laser amplifier using a Er,Yb:glass planar waveguide for coherent Doppler lidar

NASA Astrophysics Data System (ADS)

Sakimura, Takeshi; Watanabe, Yojiro; Ando, Toshiyuki; Kameyama, Shumpei; Asaka, Kimio; Tanaka, Hisamichi; Yanagisawa, Takayuki; Hirano, Yoshihito; Inokuchi, Hamaki

2012-11-01

We have developed a 1.5-μm eye-safe wavelength high average power laser amplifier using an Er,Yb:glass planar waveguide for coherent Doppler LIDAR. Large cooling surface of the planar waveguide enabled high average power pumping for Er,Yb:glass which has low thermal fracture limit. Nonlinear effects are suppressed by the large beam size which is designed by the waveguide thickness and the beam width of the planar direction. Multi-bounce optical path configuration and high-intensity pumping provide high-gain and high-efficient operation using three-level laser material. With pulsed operation, the maximum pulse energy of 1.9 mJ was achieved at the repetition rate of 4 kHz. Output average power of the amplified signal was 7.6W with the amplified gain of more than 20dB. This amplifier is suitable for coherent Doppler LIDAR to enhance the measurable range.

Tunable optical switching in the near-infrared spectral regime by employing plasmonic nanoantennas containing phase change materials.

PubMed

Savaliya, Priten B; Thomas, Arun; Dua, Rishi; Dhawan, Anuj

2017-10-02

We propose the design of switchable plasmonic nanoantennas (SPNs) that can be employed for optical switching in the near-infrared regime. The proposed SPNs consist of nanoantenna structures made up of a plasmonic metal (gold) such that these nanoantennas are filled with a switchable material (vanadium dioxide). We compare the results of these SPNs with inverted SPN structures that consist of gold nanoantenna structures surrounded by a layer of vanadium dioxide (VO 2 ) on their outer surface. These nanoantennas demonstrate switching of electric-field intensity enhancement (EFIE) between two states (On and Off states), which can be induced thermally, optically or electrically. The On and Off states of the nanoantennas correspond to the metallic and semiconductor states, respectively of the VO 2 film inside or around the nanoantennas, as the VO 2 film exhibits phase transition from its semiconductor state to the metallic state upon application of thermal, optical, or electrical energy. We employ finite-difference time-domain (FDTD) simulations to demonstrate switching in the EFIE for four different SPN geometries - nanorod-dipole, bowtie, planar trapezoidal toothed log-periodic, and rod-disk - and compare their near-field distributions for the On and Off states of the SPNs. We also demonstrate that the resonance wavelength of the EFIE spectra gets substantially modified when these SPNs switch between the two states.

High-yield, ultrafast, surface plasmon-enhanced, Au nanorod optical field electron emitter arrays.

PubMed

Hobbs, Richard G; Yang, Yujia; Fallahi, Arya; Keathley, Philip D; De Leo, Eva; Kärtner, Franz X; Graves, William S; Berggren, Karl K

2014-11-25

Here we demonstrate the design, fabrication, and characterization of ultrafast, surface-plasmon enhanced Au nanorod optical field emitter arrays. We present a quantitative study of electron emission from Au nanorod arrays fabricated by high-resolution electron-beam lithography and excited by 35 fs pulses of 800 nm light. We present accurate models for both the optical field enhancement of Au nanorods within high-density arrays, and electron emission from those nanorods. We have also studied the effects of surface plasmon damping induced by metallic interface layers at the substrate/nanorod interface on near-field enhancement and electron emission. We have identified the peak optical field at which the electron emission mechanism transitions from a 3-photon absorption mechanism to strong-field tunneling emission. Moreover, we have investigated the effects of nanorod array density on nanorod charge yield, including measurement of space-charge effects. The Au nanorod photocathodes presented in this work display 100-1000 times higher conversion efficiency relative to previously reported UV triggered emission from planar Au photocathodes. Consequently, the Au nanorod arrays triggered by ultrafast pulses of 800 nm light in this work may outperform equivalent UV-triggered Au photocathodes, while also offering nanostructuring of the electron pulse produced from such a cathode, which is of interest for X-ray free-electron laser (XFEL) development where nanostructured electron pulses may facilitate more efficient and brighter XFEL radiation.

Leakage current suppression with a combination of planarized gate and overlap/off-set structure in metal-induced laterally crystallized polycrystalline-silicon thin-film transistors

NASA Astrophysics Data System (ADS)

Chae, Hee Jae; Seok, Ki Hwan; Lee, Sol Kyu; Joo, Seung Ki

2018-04-01

A novel inverted staggered metal-induced laterally crystallized (MILC) polycrystalline-silicon (poly-Si) thin-film transistors (TFTs) with a combination of a planarized gate and an overlap/off-set at the source-gate/drain-gate structure were fabricated and characterized. While the MILC process is advantageous for fabricating inverted staggered poly-Si TFTs, MILC TFTs reveal higher leakage current than TFTs crystallized by other processes due to their high trap density of Ni contamination. Due to this drawback, the planarized gate and overlap/off-set structure were applied to inverted staggered MILC TFTs. The proposed device shows drastic suppression of leakage current and pinning phenomenon by reducing the lateral electric field and the space-charge limited current from the gate to the drain.

Photoacoustic imaging with planoconcave optical microresonator sensors: feasibility studies based on phantom imaging

NASA Astrophysics Data System (ADS)

Guggenheim, James A.; Zhang, Edward Z.; Beard, Paul C.

2017-03-01

The planar Fabry-Pérot (FP) sensor provides high quality photoacoustic (PA) images but beam walk-off limits sensitivity and thus penetration depth to ≍1 cm. Planoconcave microresonator sensors eliminate beam walk-off enabling sensitivity to be increased by an order-of-magnitude whilst retaining the highly favourable frequency response and directional characteristics of the FP sensor. The first tomographic PA images obtained in a tissue-realistic phantom using the new sensors are described. These show that the microresonator sensors provide near identical image quality as the planar FP sensor but with significantly greater penetration depth (e.g. 2-3cm) due to their higher sensitivity. This offers the prospect of whole body small animal imaging and clinical imaging to depths previously unattainable using the FP planar sensor.

Gas temperature and density measurements based on spectrally resolved Rayleigh-Brillouin scattering

NASA Technical Reports Server (NTRS)

Seasholtz, Richard G.; Lock, James A.

1992-01-01

The use of molecular Rayleigh scattering for measurements of gas density and temperature is evaluated. The technique used is based on the measurement of the spectrum of the scattered light, where both temperature and density are determined from the spectral shape. Planar imaging of Rayleigh scattering from air using a laser light sheet is evaluated for ambient conditions. The Cramer-Rao lower bounds for the shot-noise limited density and temperature measurement uncertainties are calculated for an ideal optical spectrum analyzer and for a planar mirror Fabry-Perot interferometer used in a static, imaging mode. With this technique, a single image of the Rayleigh scattered light can be analyzed to obtain density (or pressure) and temperature. Experimental results are presented for planar measurements taken in a heated air stream.

Observations and consequences of nonuniform aluminum concentrations in the channel regions of AlGaAs channeled-substrate-planar lasers

NASA Technical Reports Server (NTRS)

Evans, Gary A.; Goldstein, Bernard; Butler, Jerome K.

1987-01-01

Compositional changes in the n-clad layer within the channel region of channel substrate planar (CSP) type semiconductor lasers have been observed. As a consequece, a large optical cavity (LOC) or an enhanced substrate loss (ESL) version of the CSP geometry may result, both of which may have significantly different characteristics from those of a conventional CSP laser. The CSP-LOC generally has a larger near-field spot size, while the ESL-CSP is characterized by an off-axis, asymmetric far-field pattern.

Planar temperature measurement in compressible flows using laser-induced iodine fluorescence

NASA Technical Reports Server (NTRS)

Hartfield, Roy J., Jr.; Hollo, Steven D.; Mcdaniel, James C.

1991-01-01

A laser-induced iodine fluorescence technique that is suitable for the planar measurement of temperature in cold nonreacting compressible air flows is investigated analytically and demonstrated in a known flow field. The technique is based on the temperature dependence of the broadband fluorescence from iodine excited by the 514-nm line of an argon-ion laser. Temperatures ranging from 165 to 245 K were measured in the calibration flow field. This technique makes complete, spatially resolved surveys of temperature practical in highly three-dimensional, low-temperature compressible flows.

Multiple Beam Optical Processing

DTIC Science & Technology

1989-12-01

the interference of multiple reflections between the two mirrors. The most promising optical bistable devices, at present, are very thin, solid Fabry...MEDIUM b) R - Ir ,, PMASE SHIFTr Figure 1.3 (a) Nonlinear Fabry-Perot etalon consisting of solid material with parallel surfaces with coatings of...instead of the solid planar structure [2.10]. Voids between columns cause an Inhomogeneous broadening and an exponential extension (Urbach tail) of the

Integrated-optical directional coupler biosensor

NASA Astrophysics Data System (ADS)

Luff, B. J.; Harris, R. D.; Wilkinson, J. S.; Wilson, R.; Schiffrin, D. J.

1996-04-01

We present measurements of biomolecular binding reactions, using a new type of integrated-optical biosensor based on a planar directional coupler structure. The device is fabricated by Ag+ - Na+ ion exchange in glass, and definition of the sensing region is achieved by use of transparent fluoropolymer isolation layers formed by thermal evaporation. The suitability of the sensor for application to the detection of environmental pollutants is considered.

Anti resonant reflecting optical waveguide structure based on oxidized porous silicon for label free bio sensing applications

NASA Astrophysics Data System (ADS)

Haji, L.; Hiraoui, M.; Lorrain, N.; Guendouz, M.

2012-03-01

In this letter we report on the use of an electrochemical process for the fabrication of anti resonant reflecting optical waveguide based on oxidized porous silicon. This method is known to allow the formation of various photonic structures (Bragg mirror, microcavity), thanks to the easy and in situ modulation of the porosity and thus of the refractive index. Planar anti resonant reflecting optical waveguide structure made from porous silicon is demonstrated to be very effective for low losses as compared to conventional resonant waveguide. Optical measurements carried out for TE and TM polarizations are reported and related to optical sensing.

Optical study of hydrogen-irradiated GaAsN/GaAs heterostructures

NASA Astrophysics Data System (ADS)

Geddo, M.; Patrini, M.; Guizzetti, G.; Galli, M.; Trotta, R.; Polimeni, A.; Capizzi, M.; Martelli, F.; Rubini, S.

2011-06-01

The effect of hydrogen irradiation on the optical properties of GaAs1-xNx/GaAs heterostructures was investigated using photoreflectance and reflectance techniques. Systematic measurements performed on both as-grown and hydrogenated samples for N-concentrations ranging from 0.0% to 3.5% and for H-implanted doses from 3 × 1018 to 6 × 1018 ions/cm2 have shown that (a) the H-induced widening of the energy gap is accompanied by a decrease of the refractive index of the H-treated samples with respect to the as-grown ones, resulting in an index mismatch that can be as large as 2% in the subgap spectral region; and (b) the presence of compressive strain in fully passivated GaAsN determines a decrease of the refractive index even below that of GaAs that can be eliminated via moderate thermal annealing. These findings are promising for the development of heterostructures with planar geometry, in which the simultaneous confinement of both carriers and photons, even on a nanometric scale, can be obtained in a single step process.

Multichannel waveguides for the simultaneous detection of disease biomarkers

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

Mukundan, Harshini; Price, Dominique Z; Grace, Wynne K

2009-01-01

The sensor team at the Los Alamos National Laboratory has developed a waveguide-based optical biosensor that has previously been used for the detection of biomarkers associated with diseases such as tuberculosis, breast cancer, anthrax and influenza in complex biological samples (e.g., serum and urine). However, no single biomarker can accurately predict disease. To address this issue, we developed a multiplex assay for the detection of components of the Bacillus anthracis lethal toxin on single mode planar optical waveguides with tunable quantum dots as the fluorescence reporter. This limited ability to multiplex is still insufficient for accurate detection of disease ormore » for monitoring prognosis. In this manuscript, we demonstrate for the first time, the design, fabrication and successful evaluation of a multichannel planar optical waveguide for the simultaneous detection of at least three unknown samples in quadruplicate. We demonstrate the simultaneous, rapid (30 min), quantitative (with internal standard) and sensitive (limit of detection of 1 pM) detection of protective antigen and lethal factor of Bacillus anthracis in complex biological samples (serum) using specific monoclonal antibodies labeled with quantum dots as the fluorescence reporter.« less

Characterization of Si3N4/SiO2 optical channel waveguides by photon scanning tunneling microscopy

NASA Technical Reports Server (NTRS)

Wang, Yan; Chudgar, Mona H.; Jackson, Howard E.; Miller, Jeffrey S.; De Brabander, Gregory N.; Boyd, Joseph T.

1993-01-01

Photon scanning tunneling microscopy (PSTM) is used to characterize Si3N4/Si02 optical channel waveguides being used for integrated optical-micromechanical sensors. PSTM utilizes an optical fiber tapered to a fine point which is piezoelectrically positioned to measure the decay of the evanescent field intensity associated with the waveguide propagating mode. Evanescent field decays are recorded for both ridge channel waveguides and planar waveguide regions. Values for the local effective refractive index are calculated from the data for both polarizations and compared to model calculations.

Temperature insensitive and ultra wideband silica-based dual polarization optical hybrid for coherent receiver with highly symmetrical interferometer design.

PubMed

Nasu, Yusuke; Mizuno, Takayuki; Kasahara, Ryoichi; Saida, Takashi

2011-12-12

To extend the operation wavelength range of dual-polarization optical hybrids (DPOH), we propose a highly symmetrical interferometer design for a polarization beam splitter and an optical hybrid to reduce temperature and wavelength dependence. The design successfully decreases this dependence, and a fabricated DPOH with silica-based planar lightwave circuits provides temperature-insensitive performance with a polarization extinction ratio of over 25 dB and phase errors of less than 3 degrees over the entire C- and L-bands. © 2011 Optical Society of America

Solvent-assisted lipid bilayer formation on silicon dioxide and gold.

PubMed

Tabaei, Seyed R; Choi, Jae-Hyeok; Haw Zan, Goh; Zhdanov, Vladimir P; Cho, Nam-Joon

2014-09-02

Planar lipid bilayers on solid supports mimic the fundamental structure of biological membranes and can be investigated using a wide range of surface-sensitive techniques. Despite these advantages, planar bilayer fabrication is challenging, and there are no simple universal methods to form such bilayers on diverse material substrates. One of the novel methods recently proposed and proven to form a planar bilayer on silicon dioxide involves lipid deposition in organic solvent and solvent exchange to influence the phase of adsorbed lipids. To scrutinize the specifics of this solvent-assisted lipid bilayer (SALB) formation method and clarify the limits of its applicability, we have developed a simplified, continuous solvent-exchange version to form planar bilayers on silicon dioxide, gold, and alkanethiol-coated gold (in the latter case, a lipid monolayer is formed to yield a hybrid bilayer) and varied the type of organic solvent and rate of solvent exchange. By tracking the SALB formation process with simultaneous quartz crystal microbalance-dissipation (QCM-D) and ellipsometry, it was determined that the acoustic, optical, and hydration masses along with the acoustic and optical thicknesses, measured at the end of the process, are comparable to those observed by employing conventional fabrication methods (e.g., vesicle fusion). As shown by QCM-D measurements, the obtained planar bilayers are highly resistant to protein adsorption, and several, but not all, water-miscible organic solvents could be successfully used in the SALB procedure, with isopropanol yielding particularly high-quality bilayers. In addition, fluorescence recovery after photobleaching (FRAP) measurements demonstrated that the coefficient of lateral lipid diffusion in the fabricated bilayers corresponds to that measured earlier in the planar bilayers formed by vesicle fusion. With increasing rate of solvent exchange, it was also observed that the bilayer became incomplete and a phenomenological model was developed in order to explain this feature. The results obtained allowed us to clarify and discriminate likely steps of the SALB formation process as well as determine the corresponding influence of organic solvent type and flow conditions on these steps. Taken together, the findings demonstrate that the SALB formation method can be adapted to a continuous solvent-exchange procedure that is technically minimal, quick, and efficient to form planar bilayers on solid supports.

Active control of electromagnetic radiation through an enhanced thermo-optic effect

PubMed Central

Sheng, Chong; Liu, Hui; Zhu, Shining; Genov, Dentcho A.

2015-01-01

The control of electromagnetic radiation in transformation optical metamaterials brings the development of vast variety of optical devices. Of a particular importance is the possibility to control the propagation of light with light. In this work, we use a structured planar cavity to enhance the thermo-optic effect in a transformation optical waveguide. In the process, a control laser produces apparent inhomogeneous refractive index change inside the waveguides. The trajectory of a second probe laser beam is then continuously tuned in the experiment. The experimental results agree well with the developed theory. The reported method can provide a new approach toward development of transformation optical devices where active all-optical control of the impinging light can be achieved. PMID:25746689

Crucial role of molecular planarity on the second order nonlinear optical property of pyridine based chalcone single crystals

NASA Astrophysics Data System (ADS)

Menezes, Anthoni Praveen; Jayarama, A.; Ng, Seik Weng

2015-05-01

An efficient nonlinear optical material 2E-3-(4-bromophenyl)-1-(pyridin-3-yl) prop-2-en-1-one (BPP) was synthesized and single crystals were grown using slow evaporation solution growth technique at room temperature. Grown crystal had prismatic morphology and its structure was confirmed by various spectroscopic studies, elemental analysis, and single crystal X-ray diffraction (XRD) technique. The single crystal XRD of the crystal showed that BPP crystallizes in monoclinic system with noncentrosymmetric space group P21 and the cell parameters are a = 5.6428(7) Å, b = 3.8637(6) Å, c = 26.411(2) Å, β = 97.568(11) deg and v = 575.82(12) Å3. The UV-Visible spectrum reveals that the crystal is optically transparent and has high optical energy band gap of 3.1 eV. The powder second harmonic generation efficiency (SHG) of BPP is 6.8 times that of KDP. From thermal analysis it is found that the crystal melts at 139 °C and decomposes at 264 °C. High optical transparency down to blue region, higher powder SHG efficiency and better thermal stability than that of urea makes this chalcone derivative a promising candidate for SHG applications. Furthermore, effect of molecular planarity on SHG efficiency and role of pyridine ring adjacent to carbonyl group in forming noncentrosymmetric crystal systems of chalcone family is also discussed.

Nonholonomic Ofject Tracking with Optical Sensors and Ofject Recognition Feedback

NASA Technical Reports Server (NTRS)

Goddard, R. E.; Hadaegh, F.

1994-01-01

Robotic controllers frequently operate under constraints. Often, the constraints are imperfectly or completely unknown. In this paper, the Lagrangian dynamics of a planar robot arm are expressed as a function of a globally unknown consraint.

Bragg gratings: Optical microchip sensors

NASA Astrophysics Data System (ADS)

Watts, Sam

2010-07-01

A direct UV writing technique that can create multiple Bragg gratings and waveguides in a planar silica-on-silicon chip is enabling sensing applications ranging from individual disposable sensors for biotechnology through to multiplexed sensor networks in pharmaceutical manufacturing.

Direct optical measurement of light coupling into planar waveguide by plasmonic nanoparticles.

PubMed

Pennanen, Antti M; Toppari, J Jussi

2013-01-14

Coupling of light into a thin layer of high refractive index material by plasmonic nanoparticles has been widely studied for application in photovoltaic devices, such as thin-film solar cells. In numerous studies this coupling has been investigated through measurement of e.g. quantum efficiency or photocurrent enhancement. Here we present a direct optical measurement of light coupling into a waveguide by plasmonic nanoparticles. We investigate the coupling efficiency into the guided modes within the waveguide by illuminating the surface of a sample, consisting of a glass slide coated with a high refractive index planar waveguide and plasmonic nanoparticles, while directly measuring the intensity of the light emitted out of the waveguide edge. These experiments were complemented by transmittance and reflectance measurements. We show that the light coupling is strongly affected by thin-film interference, localized surface plasmon resonances of the nanoparticles and the illumination direction (front or rear).

FIBRE AND INTEGRATED OPTICS. OPTICAL PROCESSING OF INFORMATION: Feasibility of using waveguide holograms in systems for the transfer of amplitude—phase information along fibre communication lines

NASA Astrophysics Data System (ADS)

Dianov, Evgenii M.; Zubov, Vladimir A.; Putilin, A. N.

1995-02-01

An analysis is made of a variant of a system for spatial—temporal transformation of spatially one-dimensional information for its transfer along a single-mode fibre waveguide. Information is coupled into a fibre by a waveguide hologram. This hologram forms a light-beam structure which matches the fibre-guided mode. A report is given of the use of ion-exchange planar glass waveguides as waveguide holograms. An amorphous chalcogenide semiconductor film or a photoresist was deposited by evaporation on such a planar waveguide. Reconstruction of the waveguide hologram made it possible to achieve a high read rate, up to 1011 pixels per second, when a short radiation pulse was used. Multisectioned injection semiconductor lasers, operating under Q-switching conditions, were used as the radiation sources.

The frequency-dependent directivity of a planar fabry-perot polymer film ultrasound sensor.

PubMed

Cox, Benjamin T; Beard, Paul C

2007-02-01

A model of the frequency-dependent directivity of a planar, optically-addressed, Fabry-Perot (FP), polymer film ultrasound sensor is described and validated against experimental directivity measurements made over a frequency range of 1 to 15 MHz and angles from normal incidence to 80 degrees. The model may be used, for example, as a predictive tool to improve sensor design, or to provide a noise-free response function that could be deconvolved from sound-field measurements in order to improve accuracy in high-frequency metrology and imaging applications. The specific question of whether effective element sizes as small as the optical-diffraction limit can be achieved was investigated. For a polymer film sensor with a FP cavity of thickness d, the minimum effective element radius was found to be about 0.9 d, and that an illumination spot radius of less than d/4 is required to achieve it.

A ten-element array of individually addressable channeled-substrate-planar AlGaAs diode lasers

NASA Technical Reports Server (NTRS)

Carlin, D. B.; Goldstein, B.; Bednarz, J. P.; Harvey, M. G.; Dinkel, N. A.

1987-01-01

The fabrication of arrays of channeled-substrate-planar (CSP) AlGaAs diode lasers which emit up to 150 mW CW in a single spatial mode and are applicable to mulitchannel optical recording systems is described. The CSP diode lasers are incorporated in ten-array geometry, and each array is 1.95 nm in width and 100 microns in thickness and is cleaved to have a cavity length of 200 microns and coated to produce 90-percent reflectivity on the back facet and 10-percent reflectivity on the front facet. The array is attached to a thermoelectrically cooled submount. The optical output power versus input current characteristics for the array are evaluated, and the lateral far-field intensity profiles for each of the lasers (at 30 mW CW) and CW spectra of the lasers are analyzed.

Buffer layer between a planar optical concentrator and a solar cell

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

Solano, Manuel E.; Barber, Greg D.; Department of Chemistry, Pennsylvania State University, University Park, PA 16802

2015-09-15

The effect of inserting a buffer layer between a periodically multilayered isotropic dielectric (PMLID) material acting as a planar optical concentrator and a photovoltaic solar cell was theoretically investigated. The substitution of the photovoltaic material by a cheaper dielectric material in a large area of the structure could reduce the fabrication costs without significantly reducing the efficiency of the solar cell. Both crystalline silicon (c-Si) and gallium arsenide (GaAs) were considered as the photovoltaic material. We found that the buffer layer can act as an antireflection coating at the interface of the PMLID and the photovoltaic materials, and the structuremore » increases the spectrally averaged electron-hole pair density by 36% for c-Si and 38% for GaAs compared to the structure without buffer layer. Numerical evidence indicates that the optimal structure is robust with respect to small changes in the grating profile.« less

Instructional Review: An Introduction to Optical Methods for Characterizing Liquid Crystals at Interfaces

PubMed Central

Miller, Daniel S.; Carlton, Rebecca J.; Mushenheim, Peter C.; Abbott, Nicholas L.

2013-01-01

This Instructional Review describes methods and underlying principles that can be used to characterize both the orientations assumed spontaneously by liquid crystals (LCs) at interfaces and the strength with which the LCs are held in those orientations (so-called anchoring energies). The application of these methods to several different classes of LC interfaces is described, including solid and aqueous interfaces as well as planar and non-planar interfaces (such as those that define a LC-in-water emulsion droplet). These methods, which enable fundamental studies of the ordering of LCs at polymeric, chemically-functionalized and biomolecular interfaces, are described in this article at a level that can be easily understood by a non-expert reader such as an undergraduate or graduate student. We focus on optical methods because they are based on instrumentation that is found widely in research and teaching laboratories. PMID:23347378

GRIN planar waveguide concentrator used with a single axis tracker.

PubMed

Bouchard, Sébastien; Thibault, Simon

2014-03-10

It is generally accepted that small to medium level concentrators could be used as cost-competitive replacements for tracked solar panels. The objective is to design a system that can reach a good level of sun concentration with only one sun-tracking axis and is cheap to fabricate. As the most critical parameter for all concentrator designs, optical efficiency needed improvement to reduce the cost of power produced by our system. By using a graded-index planar waveguide with an index profile similar to SELFOC fiber, the ray's path can be controlled. Also, the concentrator can be fabricated in a single block, which reduces Fresnel reflections. Overall, the optical efficiency can be improved by as much as 33% compared to the same system made with a homogeneous waveguide. Furthermore, the ability to cost-effectively fabricate the concentrator by molding can be preserved, making it possible to reduce the cost of the solar power produced.

GRIN planar waveguide concentrator used with a single axis tracker.

PubMed

Bouchard, Sébastien; Thibault, Simon

2014-03-10

It is generally accepted that small to medium level concentrators could be used as cost-competitive replacements for tracked solar panels. The objective is to design a system that can reach a good level of sun concentration with only one sun-tracking axis and is cheap to fabricate. As the most critical parameter for all concentrator designs, optical efficiency needed improvement to reduce the cost of power produced by our system. By using a graded-index planar waveguide with an index profile similar to SELFOC fiber, the ray’s path can be controlled. Also, the concentrator can be fabricated in a single block, which reduces Fresnel reflections. Overall, the optical efficiency can be improved by as much as 33% compared to the same system made with a homogeneous waveguide. Furthermore, the ability to cost-effectively fabricate the concentrator by molding can be preserved, making it possible to reduce the cost of the solar power produced.

Broadband and wide-angle light harvesting by ultra-thin silicon solar cells with partially embedded dielectric spheres.

PubMed

Yang, Zhenhai; Shang, Aixue; Qin, Linling; Zhan, Yaohui; Zhang, Cheng; Gao, Pingqi; Ye, Jichun; Li, Xiaofeng

2016-04-01

We propose a design of crystalline silicon thin-film solar cells (c-Si TFSCs, 2 μm-thick) configured with partially embedded dielectric spheres on the light-injecting side. The intrinsic light trapping and photoconversion are simulated by the complete optoelectronic simulation. It shows that the embedding depth of the spheres provides an effective way to modulate and significantly enhance the optical absorption. Compared to the conventional planar and front sphere systems, the optimized partially embedded sphere design enables a broadband, wide-angle, and strong optical absorption and efficient carrier transportation. Optoelectronic simulation predicts that a 2 μm-thick c-Si TFSC with half-embedded spheres shows an increment of more than 10  mA/cm² in short-circuit current density and an enhancement ratio of more than 56% in light-conversion efficiency, compared to the conventional planar counterparts.

Cellular dye lasers: lasing thresholds and sensing in a planar resonator

PubMed Central

Humar, Matjaž; Gather, Malte C.; Yun, Seok-Hyun

2015-01-01

Biological cell lasers are promising novel building blocks of future biocompatible optical systems and offer new approaches to cellular sensing and cytometry in a microfluidic setting. Here, we demonstrate a simple method for providing optical gain by using a variety of standard fluorescent dyes. The dye gain medium can be located inside or outside a cell, or in both, which gives flexibility in experimental design and makes the method applicable to all cell types. Due to the higher refractive index of the cytoplasm compared to the surrounding medium, a cell acts as a convex lens in a planar Fabry-Perot cavity. Its effect on the stability of the laser cavity is analyzed and utilized to suppress lasing outside cells. The resonance modes depend on the shape and internal structure of the cell. As proof of concept, we show how the laser output modes are affected by the osmotic pressure. PMID:26480446

Tunable all-optical photonic crystal channel drop filter for DWDM systems

NASA Astrophysics Data System (ADS)

Habibiyan, H.; Ghafoori-Fard, H.; Rostami, A.

2009-06-01

In this paper we propose a tunable channel drop filter in a two-dimensional photonic crystal, based on coupled-cavity waveguides with alternating small and large defects and an electromagnetically induced transparency phenomenon. By utilizing this phenomenon a narrower linewidth is obtained and also the frequency of the dropped signal becomes tunable. Simulation results show that the proposed filter is suitable for dense wavelength-division multiplexing (DWDM) systems with 0.8 nm channel spacing. Using this novel component, two ultrasmall eight-channel double-sided and single-sided demultiplexers are introduced. The properties of these devices are investigated using the finite-difference time-domain method. For the single-sided device, transmission loss is 1.5 ± 0.5 dB, the cross-talk level between adjacent channels is better than -18 dB and the average 3 dB optical passband is 0.36 nm. Using planar silicon-on-insulator technology, the physical area for the single-sided component is 700 µm2 and for the double-sided component is 575 µm2. To the best of our knowledge, these are the smallest all-optical demultiplexers with this spectral resolution reported to date. Malfunction of the proposed device due to fabrication errors is modeled and its tunable characteristic is demonstrated.

Tuning a circular p-n junction in graphene from quantum confinement to optical guiding

NASA Astrophysics Data System (ADS)

Jiang, Yuhang; Mao, Jinhai; Moldovan, Dean; Masir, Massoud Ramezani; Li, Guohong; Watanabe, Kenji; Taniguchi, Takashi; Peeters, Francois M.; Andrei, Eva Y.

2017-11-01

The photon-like propagation of the Dirac electrons in graphene, together with its record-high electronic mobility, can lead to applications based on ultrafast electronic response and low dissipation. However, the chiral nature of the charge carriers that is responsible for the high mobility also makes it difficult to control their motion and prevents electronic switching. Here, we show how to manipulate the charge carriers by using a circular p-n junction whose size can be continuously tuned from the nanometre to the micrometre scale. The junction size is controlled with a dual-gate device consisting of a planar back gate and a point-like top gate made by decorating a scanning tunnelling microscope tip with a gold nanowire. The nanometre-scale junction is defined by a deep potential well created by the tip-induced charge. It traps the Dirac electrons in quantum-confined states, which are the graphene equivalent of the atomic collapse states (ACSs) predicted to occur at supercritically charged nuclei. As the junction size increases, the transition to the optical regime is signalled by the emergence of whispering-gallery modes, similar to those observed at the perimeter of acoustic or optical resonators, and by the appearance of a Fabry-Pérot interference pattern for junctions close to a boundary.

Analysis and design of planar waveguide elements for use in filters and sensors

NASA Astrophysics Data System (ADS)

Chen, Guangzhou

In this dissertation we present both theoretical analysis and practical design considerations for planar optical waveguide devices. The analysis takes into account both transverse dimensions of the waveguides and is based on supermode theory combined with the resonance method for the determination of the propagation constants and field profiles of the supermodes. An improved accuracy has been achieved by including corrections due to the fields in the corner regions of the waveguides using perturbation theory. We analyze in detail two particular devices, an optical filter/combiner and an optical sensor. An optical wavelength filter/combiner is a common element in an integrated optical circuit. A new "bend free" filter/combiner is proposed and analyzed. The new wavelength filter consists of only straight parallel channels, which considerably simplify both the analysis and fabrication of the device. We show in detail how the operation of the device depends upon each of the design parameters. The intrinsic power loss in the proposed filter/combiner is minimized. The optical sensor is another important device and the sensitivity of measurement is an important issue in its design. Two operating mechanisms used in prior optical sensors are evanescent wave sensing or surface plasmon excitation. In this dissertation, we present a sensor with a directional coupler structure in which a measurand to be detected is interfaced with one side of the cladding. The analysis shows that it is possible to make a high resolution device by adjusting the design parameters. The dimensions and materials used in an optimized design are presented.

Design of the first optical system for real-time tomographic holography (RTTH)

NASA Astrophysics Data System (ADS)

Galeotti, John M.; Siegel, Mel; Rallison, Richard D.; Stetten, George

2008-08-01

The design of the first Real-Time-Tomographic-Holography (RTTH) optical system for augmented-reality applications is presented. RTTH places a viewpoint-independent real-time (RT) virtual image (VI) of an object into its actual location, enabling natural hand-eye coordination to guide invasive procedures, without requiring tracking or a head-mounted device. The VI is viewed through a narrow-band Holographic Optical Element (HOE) with built-in power that generates the largest possible near-field, in-situ VI from a small display chip without noticeable parallax error or obscuring direct view of the physical world. Rigidly fixed upon a medical-ultrasound probe, RTTH could show the scan in its actual location inside the patient, because the VI would move with the probe. We designed the image source along with the system-optics, allowing us to ignore both planer geometric distortions and field curvature, respectively compensated by using RT pre-processing software and attaching a custom-surfaced fiber-optic-faceplate (FOFP) to our image source. Focus in our fast, non-axial system was achieved by placing correcting lenses near the FOFP and custom-optically-fabricating our volume-phase HOE using a recording beam that was specially shaped by extra lenses. By simultaneously simulating and optimizing the system's playback performance across variations in both the total playback and HOE-recording optical systems, we derived and built a design that projects a 104x112 mm planar VI 1 m from the HOE using a laser-illuminated 19x16 mm LCD+FOFP image-source. The VI appeared fixed in space and well focused. Viewpoint-induced location errors were <3 mm, and unexpected first-order astigmatism produced 3 cm (3% of 1 m) ambiguity in depth, typically unnoticed by human observers.

Laser-Induced Thermal Acoustics Theory and Expected Experimental Errors when Applied to a Scramjet Isolator Model

NASA Technical Reports Server (NTRS)

Middleton, Troy F.; Balla, Robert Jeffrey; Baurle, Robert A.; Wilson, Lloyd G.

2011-01-01

A scramjet isolator model test apparatus is being assembled in the Isolator Dynamics Research Lab (IDRL) at the NASA Langley Research Center in Hampton, Virginia. The test apparatus is designed to support multiple measurement techniques for investigating the flow field in a scramjet isolator model. The test section is 1-inch high by 2-inch wide by 24-inch long and simulates a scramjet isolator with an aspect ratio of two. Unheated, dry air at a constant stagnation pressure and temperature is delivered to the isolator test section through a Mach 2.5 planar nozzle. The isolator test section is mechanically back-pressured to contain the resulting shock train within the 24-inch isolator length and supports temperature, static pressure, and high frequency pressure measurements at the wall. Additionally, nonintrusive methods including laser-induced thermal acoustics (LITA), spontaneous Raman scattering, particle image velocimetry, and schlieren imaging are being incorporated to measure off-wall fluid dynamic, thermodynamic, and transport properties of the flow field. Interchangeable glass and metallic sidewalls and optical access appendages permit making multiple measurements simultaneously. The measurements will be used to calibrate computational fluid dynamics turbulence models and characterize the back-pressured flow of a scramjet isolator. This paper describes the test apparatus, including the optical access appendages; the physics of the LITA method; and estimates of LITA measurement uncertainty for measurements of the speed of sound and temperature.

Quantitative in vivo optical tomography of cancer progression & vasculature development in adult zebrafish

PubMed Central

Kumar, Sunil; Lockwood, Nicola; Ramel, Marie-Christine; Correia, Teresa; Ellis, Matthew; Alexandrov, Yuriy; Andrews, Natalie; Patel, Rachel; Bugeon, Laurence; Dallman, Margaret J.; Brandner, Sebastian; Arridge, Simon; Katan, Matilda; McGinty, James; Frankel, Paul; French, Paul M.W.

2016-01-01

We describe a novel approach to study tumour progression and vasculature development in vivo via global 3-D fluorescence imaging of live non-pigmented adult zebrafish utilising angularly multiplexed optical projection tomography with compressive sensing (CS-OPT). This “mesoscopic” imaging method bridges a gap between established ~μm resolution 3-D fluorescence microscopy techniques and ~mm-resolved whole body planar imaging and diffuse tomography. Implementing angular multiplexing with CS-OPT, we demonstrate the in vivo global imaging of an inducible fluorescently labelled genetic model of liver cancer in adult non-pigmented zebrafish that also present fluorescently labelled vasculature. In this disease model, addition of a chemical inducer (doxycycline) drives expression of eGFP tagged oncogenic K-RASV12 in the liver of immune competent animals. We show that our novel in vivo global imaging methodology enables non-invasive quantitative imaging of the development of tumour and vasculature throughout the progression of the disease, which we have validated against established methods of pathology including immunohistochemistry. We have also demonstrated its potential for longitudinal imaging through a study of vascular development in the same zebrafish from early embryo to adulthood. We believe that this instrument, together with its associated analysis and data management tools, constitute a new platform for in vivo cancer studies and drug discovery in zebrafish disease models. PMID:27259259

Experimental demonstration of conformal phased array antenna via transformation optics.

PubMed

Lei, Juan; Yang, Juxing; Chen, Xi; Zhang, Zhiya; Fu, Guang; Hao, Yang

2018-02-28

Transformation Optics has been proven a versatile technique for designing novel electromagnetic devices and it has much wider applicability in many subject areas related to general wave equations. Among them, quasi-conformal transformation optics (QCTO) can be applied to minimize anisotropy of transformed media and has opened up the possibility to the design of broadband antennas with arbitrary geometries. In this work, a wide-angle scanning conformal phased array based on all-dielectric QCTO lens is designed and experimentally demonstrated. Excited by the same current distribution as such in a conventional planar array, the conformal system in presence of QCTO lens can preserve the same radiation characteristics of a planar array with wide-angle beam-scanning and low side lobe level (SLL). Laplace's equation subject to Dirichlet-Neumann boundary conditions is adopted to construct the mapping between the virtual and physical spaces. The isotropic lens with graded refractive index is realized by all-dielectric holey structure after an effective parameter approximation. The measurements of the fabricated system agree well with the simulated results, which demonstrate its excellent wide-angle beam scanning performance. Such demonstration paves the way to a robust but efficient array synthesis, as well as multi-beam and beam forming realization of conformal arrays via transformation optics.

Shaping the Atomic-Scale Geometries of Electrodes to Control Optical and Electrical Performance of Molecular Devices.

PubMed

Zhao, Zhikai; Liu, Ran; Mayer, Dirk; Coppola, Maristella; Sun, Lu; Kim, Youngsang; Wang, Chuankui; Ni, Lifa; Chen, Xing; Wang, Maoning; Li, Zongliang; Lee, Takhee; Xiang, Dong

2018-04-01

A straightforward method to generate both atomic-scale sharp and atomic-scale planar electrodes is reported. The atomic-scale sharp electrodes are generated by precisely stretching a suspended nanowire, while the atomic-scale planar electrodes are obtained via mechanically controllable interelectrodes compression followed by a thermal-driven atom migration process. Notably, the gap size between the electrodes can be precisely controlled at subangstrom accuracy with this method. These two types of electrodes are subsequently employed to investigate the properties of single molecular junctions. It is found, for the first time, that the conductance of the amine-linked molecular junctions can be enhanced ≈50% as the atomic-scale sharp electrodes are used. However, the atomic-scale planar electrodes show great advantages to enhance the sensitivity of Raman scattering upon the variation of nanogap size. The underlying mechanisms for these two interesting observations are clarified with the help of density functional theory calculation and finite-element method simulation. These findings not only provide a strategy to control the electron transport through the molecule junction, but also pave a way to modulate the optical response as well as to improve the stability of single molecular devices via the rational design of electrodes geometries. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Color waveguide transparent screen using lens array holographic optical element

NASA Astrophysics Data System (ADS)

Liu, Siqi; Sun, Peng; Wang, Chang; Zheng, Zhenrong

2017-11-01

A color transparent screen was designed in this paper, a planar glass was used as a waveguide structure and the lens array holographic optical element (HOE) was used as a display unit. The lens array HOE was exposed by two coherent beams. One was the reference wave which directly illuminated on the holographic material and the other was modulated by the micro lens array. The lens array HOE can display the images with see-through abilities. Unlike the conventional lens array HOE, a planar glass was adopted as the waveguide in the experiment. The projecting light was totally internal-reflected in the planar glass to eliminate the undesired zero-order diffracted light. By using waveguide, it also brings advantage of compact structure. Colorful display can be realized in our system as the holographic materials were capable for multi-wavelength display. In this paper, a color transparent screen utilizing the lens array HOE and waveguide were designed. Experiment results showed a circular display area on the transparent screen. The diameter of the area is 20 mm and it achieved the pixel resolution of 100 μm. This simple and effective method could be an alternative in the augment reality (AR) applications, such as transparent phone and television.

Spectroscopic Measurements of Planar Foil Plasmas Driven by a MA LTD

NASA Astrophysics Data System (ADS)

Patel, Sonal; Yager-Elorriaga, David; Steiner, Adam; Jordan, Nick; Gilgenbach, Ronald; Lau, Y. Y.

2014-10-01

Planar foil ablation experiments are being conducted on the Linear Transformer Driver (LTD) at the University of Michigan. The experiment consists of a 400 nm-thick, Al planar foil and a current return post. An optical fiber is placed perpendicular to the magnetic field and linear polarizers are used to isolate the pi and sigma lines. The LTD is charged to +/-70 kV with approximately 400-500 kA passing through the foil. Laser shadowgraphy has previously imaged the plasma and measured anisotropy in the Magneto Rayleigh-Taylor (MRT) instability. Localized magnetic field measurements using Zeeman splitting during the current rise is expected to yield some insight into this anisotropy. Initial experiments use Na D lines of Al foils seeded with sodium to measure Zeeman splitting. Several ion lines are also currently being studied, such as Al III and C IV, to probe the higher temperature core plasma. In planned experiments, several lens-coupled optical fibers will be placed across the foil, and local magnetic field measurements will be taken to measure current division within the plasma. This work was supported by US DoE. S.G. Patel and A.M. Steiner supported by NPSC funded by Sandia. D.A. Yager supported by NSF fellowship Grant DGE 1256260.

Fabrication of planar waveguide in KNSBN crystal by swift heavy ion beam irradiation

NASA Astrophysics Data System (ADS)

Guan, Jing; Wang, Lei; Qin, Xifeng

2013-11-01

We report on the fabrication of the planar waveguides in the KNSBN crystal by using 17 MeV C5+ ions at a fluence of 2 × 1014 ions/cm2. After implantation, near surface regions of the crystal, there has a positive extraordinary refractive index (ne) change and the light inside the waveguides can propagate in a non-leaky manner. The two-dimensional modal profiles of the planar waveguides, measured by using the end-coupling arrangement, are in good agreement with the reconstructed modal distributions. The propagation loss for C5+ irradiated waveguide is ∼0.8 dB/cm at 633 nm and ∼0.72 dB/cm at 1064 nm. The waveguide gives good confinement of waveguide modes, which exhibits acceptable guiding qualities for potential applications in integrated optics.

Free-standing GaN grating couplers and rib waveguide for planar photonics at telecommunication wavelength

NASA Astrophysics Data System (ADS)

Liu, Qifa; Wang, Wei

2018-01-01

Gallium Nitride (GaN) free-standing planar photonic device at telecommunication wavelength based on GaN-on-silicon platform was presented. The free-standing structure was realized by particular double-side fabrication process, which combining GaN front patterning, Si substrate back releasing and GaN slab etching. The actual device parameters were identified via the physical characterizations employing scanning electron microscope (SEM), atomic force microscope (AFM) and reflectance spectra testing. High coupling efficiency and good light confinement properties of the gratings and rib waveguide at telecommunication wavelength range were verified by finite element method (FEM) simulation. This work illustrates the potential of new GaN photonic structure which will enable new functions for planar photonics in communication and sensing applications, and is favorable for the realization of integrated optical circuit.

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.

Two visual observations of relevance to the search for optical counterparts of gamma-ray sources

NASA Astrophysics Data System (ADS)

Warner, B.

1986-05-01

The authors draw attention to a visual observation of a brief flash from ζ Lyrae, observed by Heis in 1850, which resembles the optical burst detected electronically by Wdowiak and Clifton (1985) from β Cam in 1969. Visual observation by the author of a second magnitude flash of very short duration is shown to originate from planar reflection from a very distant satellite. Such flashes will contribute to the "noise" in all-sky searches for optical counterparts of γ-ray bursters.

FIBER AND INTEGRATED OPTICS: Optimization of optical film waveguides

NASA Astrophysics Data System (ADS)

Adamson, P. V.

1990-10-01

Theoretical investigations were made of the possibility of optimization of the effective thickness, of the optical confinement factor Γ1, and of the birefringence of a planar dielectric waveguide as a function of the waveguide parameter V and the waveguide asymmetry. For a given value of V it is possible to ensure higher values of Γ1, for an asymmetric waveguide than for a symmetric one. An approximate expression is proposed for the factor Γ1, of an asymmetric waveguide directly in terms of its thickness and the refractive indices of the layers.

REVIEWS OF TOPICAL PROBLEMS: Recent advances in X-ray refractive optics

NASA Astrophysics Data System (ADS)

Aristov, V. V.; Shabel'nikov, L. G.

2008-01-01

X-ray refractive optics has made rapid strides to a large degree due to the work of Russian scientists, and has now become one of the most rapidly advancing areas in modern physical optics. This review outlines the results of investigation of refractive devices and analysis of their properties. The conception of planar lenses made of silicon and other materials is set forth. We discuss the applications of refractive lenses to the transformation of X-ray images, photonic crystal research, and the development of focusing devices in high-energy X-ray telescopes.

Instantaneous temperature field measurements using planar laser-induced fluorescence.

PubMed

Seitzman, J M; Kychakoff, G; Hanson, R K

1985-09-01

A single-pulse, laser-induced-fluorescence diagnostic for the measurement of two-dimensional temperature fields in combustion flows is described. The method uses sheet illumination from a tunable laser to excite planar laserinduced fluorescence in a stable tracer molecule, seeded at constant mole fraction into the flow field. The temporal resolution of this technique is determined by the laser pulse length. Experimental results are presented for a rodstabilized, premixed methane-air flame, using the Q(1) (22) line of the nitric oxide A(2) Sigma(+) (v = 0) ? X(2)II((1/2))(v = 0) transition (lambda approximately 225.6 nm).

Electromagnetically induced transparency in planar metamaterials based on guided mode resonance

NASA Astrophysics Data System (ADS)

Sun, Yaru; Chen, Hang; Li, Xiangjun; Hong, Zhi

2017-06-01

We present and numerically demonstrate a novel, electromagnetically induced transparency (EIT) in planar metamaterials (MMs) based on guided mode resonance (GMR). The unit cell of the MM consists of two metallic ring resonators. The GMR with high quality factor (Q) is achieved by changing the distance between the two rings of the MM. Narrow EIT-like spectral response is realized by coupling between a high Q GMR and a low Q dipolar resonance of the MM. Our work could provide another efficient way towards the realization of EIT with large group index using very simple structures.

Quantitative NO{sub 2} molecular tagging velocimetry at 500 kHz frame rate

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

Jiang, Naibo; Nishihara, Munetake; Lempert, Walter R.

2010-11-29

NO{sub 2} molecular tagging velocimetry (MTV) is demonstrated at repetition rates as high as 500 kHz in a laboratory scale Mach 5 wind tunnel. A pulse burst laser and a home built optical parametric oscillator system were used to simultaneously generate the required 355 and 226 nm wavelengths for NO{sub 2} photodissociation (tagging) and NO planar laser induced fluorescence imaging (interrogation), respectively. NO{sub 2} MTV images were obtained both in front and behind the characteristic bow shock from a 5 mm diameter cylinder. From Gaussian curve fitting, an average free stream flow velocity of 719 m/s was obtained. Absolute statisticalmore » precision in velocity of {approx}11.5 m/s was determined, corresponding to relative precision of 1.6%-5%, depending upon the region of the flow probed.« less

X-ray Absorption Spectroscopy Study of the Effect of Rh doping in Sr2IrO4

PubMed Central

Sohn, C. H.; Cho, Deok-Yong; Kuo, C.-T.; Sandilands, L. J.; Qi, T. F.; Cao, G.; Noh, T. W.

2016-01-01

We investigate the effect of Rh doping in Sr2IrO4 using X-ray absorption spectroscopy (XAS). We observed appearance of new electron-addition states with increasing Rh concentration (x in Sr2Ir1−xRhxO4) in accordance with the concept of hole doping. The intensity of the hole-induced state is however weak, suggesting weakness of charge transfer (CT) effect and Mott insulating ground states. Also, Ir Jeff = 1/2 upper Hubbard band shifts to lower energy as x increases up to x = 0.23. Combined with optical spectroscopy, these results suggest a hybridisation-related mechanism, in which Rh doping can weaken the (Ir Jeff = 1/2)–(O 2p) orbital hybridisation in the in-planar Rh-O-Ir bond networks. PMID:27025538

An experimental study of fluctuating pressure loads beneath swept shock/boundary-layer interactions

NASA Technical Reports Server (NTRS)

Settles, Gary S.

1991-01-01

A database is established on the fluctuating pressure loads produced on aerodynamic surfaces beneath 3-D shock wave/boundary layer interactions. Such loads constitute a fundamental problem of critical concern to future supersonic and hypersonic flight vehicles. A turbulent boundary layer on a flat plate is subjected to interactions with swept planar shock waves generated by sharp fins. Fin angles from 5 to 25 deg at freestream Mach numbers between 2.5 and 4 produce a variety of interaction strengths from weak to very strong. Miniature Kulite pressure transducers mounted in the flat plate were used to measure interaction-induced wall pressure fluctuations. These data will be correlated with proposed new optical data on the fluctuations of the interaction structure, especially that of the lambda-shock system and its associated high-speed jet impingement.

Wavelength selective switch array employing silica-based waveguide frontend with integrated polarization diversity optics.

PubMed

Sakamaki, Yohei; Shikama, Kota; Ikuma, Yuichiro; Suzuki, Kenya

2017-08-21

We propose a waveguide frontend with integrated polarization diversity optics for a wavelength selective switch (WSS) array with a liquid crystal on silicon switching engine to simplify the free space optics configuration and the alignment process in optical modules. The polarization diversity function is realized by the integration of a waveguide-type polarization beam splitter and a polarization rotating half-wave plate in a beam launcher using silica-based planar lightwave circuit technology. We confirmed experimentally the feasibility of using our proposed waveguide frontend in a two-in-one 1 × 20 WSS. The experimental results show that the fabricated waveguide frontend provides a polarization diversity function without any degradation in optical performance.

Optical chirp z-transform processor with a simplified architecture.

PubMed

Ngo, Nam Quoc

2014-12-29

Using a simplified chirp z-transform (CZT) algorithm based on the discrete-time convolution method, this paper presents the synthesis of a simplified architecture of a reconfigurable optical chirp z-transform (OCZT) processor based on the silica-based planar lightwave circuit (PLC) technology. In the simplified architecture of the reconfigurable OCZT, the required number of optical components is small and there are no waveguide crossings which make fabrication easy. The design of a novel type of optical discrete Fourier transform (ODFT) processor as a special case of the synthesized OCZT is then presented to demonstrate its effectiveness. The designed ODFT can be potentially used as an optical demultiplexer at the receiver of an optical fiber orthogonal frequency division multiplexing (OFDM) transmission system.

Theoretical description and design of nanomaterial slab waveguides: application to compensation of optical diffraction.

PubMed

Kivijärvi, Ville; Nyman, Markus; Shevchenko, Andriy; Kaivola, Matti

2018-04-02

Planar optical waveguides made of designable spatially dispersive nanomaterials can offer new capabilities for nanophotonic components. As an example, a thin slab waveguide can be designed to compensate for optical diffraction and provide divergence-free propagation for strongly focused optical beams. Optical signals in such waveguides can be transferred in narrow channels formed by the light itself. We introduce here a theoretical method for characterization and design of nanostructured waveguides taking into account their inherent spatial dispersion and anisotropy. Using the method, we design a diffraction-compensating slab waveguide that contains only a single layer of silver nanorods. The waveguide shows low propagation loss and broadband diffraction compensation, potentially allowing transfer of optical information at a THz rate.

Planar Rayleigh scattering and laser-induced fluorescence for visualization of a hot, Mach 2 annular air jet

NASA Technical Reports Server (NTRS)

Balla, R. Jeffrey

1994-01-01

Planar Rayleigh scattering (PRS) and planar laser-induced fluorescence (PLIF) were used to investigate the vitiated air component of a coaxial hydrogen/vitiated air nonpremixed turbulent jet flame that is ejected at a Mach number of 2. All experiments were performed with a xenon chloride tunable excimer laser. Planar information for both techniques was obtained using laser sheets 6 cm high, 5 cm wide, and 300 micron thick. In this flow field, the effective Rayleigh cross section of the components in the vitiated air was assumed to be independent of composition. Therefore, the PRS technique produced signals which were proportional to total density. When the flow field was assumed to be at a known and uniform pressure, the PRS signal data for the vitiated air could be converted to temperature information. Also, PLIF images were generated by probing the OH molecule. These images contain striation patterns attributed to small localized instantaneous temperature nonuniformities. The results from the PLIF and PRS techniques were used to show that this flow field contains a nongaseous component, most likely liquid water that can be reduced by increasing the settling chamber wall temperature.

Effects of repetitive pulsing on multi-kHz planar laser-induced incandescence imaging in laminar and turbulent flames

DOE PAGES

Michael, James B.; Venkateswaran, Prabhakar; Shaddix, Christopher R.; ...

2015-04-08

Planar laser-induced incandescence (LII) imaging is reported at repetition rates up to 100 kHz using a burst-mode laser system to enable studies of soot formation dynamics in highly turbulent flames. Furthermore, to quantify the accuracy and uncertainty of relative soot volume fraction measurements, the temporal evolution of the LII field in laminar and turbulent flames is examined at various laser operating conditions. Under high-speed repetitive probing, it is found that LII signals are sensitive to changes in soot physical characteristics when operating at high laser fluences within the soot vaporization regime. For these laser conditions, strong planar LII signals aremore » observed at measurement rates up to 100 kHz but are primarily useful for qualitative tracking of soot structure dynamics. However, LII signals collected at lower fluences allow sequential planar measurements of the relative soot volume fraction with a sufficient signal-to-noise ratio at repetition rates of 10–50 kHz. Finally, guidelines for identifying and avoiding the onset of repetitive probe effects in the LII signals are discussed, along with other potential sources of measurement error and uncertainty.« less

Fibrous selective emitter structures from sol-gel process

NASA Astrophysics Data System (ADS)

Chen, K. C.

1999-03-01

Selective emitters have the potential benefit of high efficiency due to the matching of emission spectra to the response of photovoltaic (PV) cells. Continuous uniform rare-earth oxide selective emitter fibers were successfully fabricated using a viscous solution made from metal organic precursors. Cylindrical- and planar configuration emitter structures were made by direct cross-winding or stacking of precursor fiber layers. The combustion and optical performance of the planar emitter structures were tested. The results indicates that both the designing of the fiber packing density and the thickness is critical for high photon and power output.

Anfo Response To Low-Stress Planar Impacts

NASA Astrophysics Data System (ADS)

Cooper, Marcia A.; Trott, Wayne M.; Schmitt, Robert G.; Short, Mark; Jackson, Scott I.

2012-03-01

Ammonium Nitrate plus Fuel Oil (ANFO) is a non-ideal explosive where the mixing behavior of the mm-diameter prills with the absorbed fuel oil is of critical importance for chemical energy release. The large-scale heterogeneity of ANFO establishes conditions uniquely suited for observation using the spatially- and temporally-resolved line-imaging ORVIS (Optically Recording Velocity Interferometer System) diagnostic. The first demonstration of transmitted wave profiles in ANFO from planar impacts using a single-stage gas gun is reported. Major observations including an extended compaction precursor, post-shock particle velocity variations and between-prill jetting are reported.

Linear guided waves in a hyperbolic planar waveguide. Dispersion relations

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

Lyashko, E I; Maimistov, A I

2015-11-30

We have theoretically investigated waveguide modes propagating in a planar waveguide formed by a layer of an isotropic dielectric surrounded by hyperbolic media. The case, when the optical axis of hyperbolic media is perpendicular to the interface, is considered. Dispersion relations are derived for the cases of TE and TM waves. The differences in the characteristics of a hyperbolic and a conventional dielectric waveguide are found. In particular, it is shown that in hyperbolic waveguides for each TM mode there are two cut-off frequencies and the number of propagating modes is always limited. (metamaterials)

Propagation of partially coherent fields through planar dielectric boundaries using angle-impact Wigner functions I. Two dimensions.

PubMed

Petruccelli, Jonathan C; Alonso, Miguel A

2007-09-01

We examine the angle-impact Wigner function (AIW) as a computational tool for the propagation of nonparaxial quasi-monochromatic light of any degree of coherence past a planar boundary between two homogeneous media. The AIWs of the reflected and transmitted fields in two dimensions are shown to be given by a simple ray-optical transformation of the incident AIW plus a series of corrections in the form of differential operators. The radiometric and leading six correction terms are studied for Gaussian Schell-model fields of varying transverse width, transverse coherence, and angle of incidence.

Investigation for connecting waveguide in off-planar integrated circuits.

PubMed

Lin, Jie; Feng, Zhifang

2017-09-01

The transmission properties of a vertical waveguide connected by different devices in off-planar integrated circuits are designed, investigated, and analyzed in detail by the finite-difference time-domain method. The results show that both guide bandwidth and transmission efficiency can be adjusted effectively by shifting the vertical waveguide continuously. Surprisingly, the wide guide band (0.385[c/a]∼0.407[c/a]) and well transmission (-6  dB) are observed simultaneously in several directions when the vertical waveguide is located at a specific location. The results are very important for all-optical integrated circuits, especially in compact integration.

Chi 3 dispersion in planar tantalum pentoxide waveguides in the telecommunications window.

PubMed

Chen, Ruiqi Y; Charlton, Martin D B; Lagoudakis, Pavlos G

2009-04-01

We report on the dispersion of the third-order nonlinear susceptibility (chi(3) or "Chi 3") in planar Ta2O5 waveguides in the telecommunications spectral window. We utilize the observation of third-harmonic generation under ultrashort pulsed excitation as a reference-free characterization method of chi(3) and obtain a large nonlinear coefficient, 2x10(-13) esu, at 1550 nm. Our observation of efficient third-harmonic generation in Ta2O5 waveguides in the telecoms window reveals the potential of this material system in high-speed integrated nonlinear optical switches.

High Speed All-Optical Data Distribution Network

NASA Astrophysics Data System (ADS)

Braun, Steve; Hodara, Henri

2017-11-01

This article describes the performance and capabilities of an all-optical network featuring low latency, high speed file transfer between serially connected optical nodes. A basic component of the network is a network interface card (NIC) implemented through a unique planar lightwave circuit (PLC) that performs add/drop data and optical signal amplification. The network uses a linear bus topology with nodes in a "T" configuration, as described in the text. The signal is sent optically (hence, no latency) to all nodes via wavelength division multiplexing (WDM), with each node receiver tuned to wavelength of choice via an optical de-multiplexer. Each "T" node routes a portion of the signal to/from the bus through optical couplers, embedded in the network interface card (NIC), to each of the 1 through n computers.

Design and simulation of a planar micro-optic free-space receiver

NASA Astrophysics Data System (ADS)

Nadler, Brett R.; Hallas, Justin M.; Karp, Jason H.; Ford, Joseph E.

2017-11-01

We propose a compact directional optical receiver for free-space communications, where a microlens array and micro-optic structures selectively couple light from a narrow incidence angle into a thin slab waveguide and then to an edge-mounted detector. A small lateral translation of the lenslet array controls the coupled input angle, enabling the receiver to select the transmitter source direction. We present the optical design and simulation of a 10mm x 10mm aperture receiver using a 30μm thick silicon waveguide able to couple up to 2.5Gbps modulated input to a 10mm x 30μm wide detector.

Precision Laser Development for Gravitational Wave Space Mission

NASA Technical Reports Server (NTRS)

Numata, Kenji; Camp, Jordan

2011-01-01

Optical fiber and semiconductor laser technologies have evolved dramatically over the last decade due to the increased demands from optical communications. We are developing a laser (master oscillator) and optical amplifier based on those technologies for interferometric space missions, such as the gravitational-wave mission LISA, and GRACE follow-on, by fully utilizing the mature wave-guided optics technologies. In space, where a simple and reliable system is preferred, the wave-guided components are advantageous over bulk, crystal-based, free-space laser, such as NPRO (Non-planar Ring Oscillator) and bulk-crystal amplifier, which are widely used for sensitive laser applications on the ground.

Planarized thick copper gate polycrystalline silicon thin film transistors for ultra-large AMOLED displays

NASA Astrophysics Data System (ADS)

Yun, Seung Jae; Lee, Yong Woo; Son, Se Wan; Byun, Chang Woo; Reddy, A. Mallikarjuna; Joo, Seung Ki

2012-08-01

A planarized thick copper (Cu) gate low temperature polycrystalline silicon (LTPS) thin film transistors (TFTs) is fabricated for ultra-large active-matrix organic light-emitting diode (AMOLED) displays. We introduce a damascene and chemical mechanical polishing process to embed a planarized Cu gate of 500 nm thickness into a trench and Si3N4/SiO2 multilayer gate insulator, to prevent the Cu gate from diffusing into the silicon (Si) layer at 550°C, and metal-induced lateral crystallization (MILC) technology to crystallize the amorphous Si layer. A poly-Si TFT with planarized thick Cu gate exhibits a field effect mobility of 5 cm2/Vs and a threshold voltage of -9 V, and a subthreshold swing (S) of 1.4 V/dec.

One-Dimensional Spontaneous Raman Measurements Made in a Gas Turbine Combustor

NASA Technical Reports Server (NTRS)

DeGroot, Wilhelmus A.; Hicks, Yolanda R.; Locke, Randy J.; Anderson, Robert C.

2001-01-01

The NASA Glenn Research Center and the aerospace industry are designing and testing low-emission combustor concepts to build the next generation of cleaner, more fuel efficient aircraft powerplants. These combustors will operate at much higher inlet temperatures and at pressures that are up to 3 to 5 times greater than combustors in the current fleet. From a test and analysis viewpoint, there is an increasing need for measurements from these combustors that are nonintrusive, simultaneous, multipoint, and more quantitative. Glenn researchers have developed several unique test facilities (refs. 1 and 2) that allow, for the first time, optical interrogation of combustor flow fields, including subcomponent performance, at pressures ranging from 1 to 60 bar (1 to 60 atm). Experiments conducted at Glenn are the first application of a visible laser-pumped, one-dimensional, spontaneous Raman-scattering technique to analyze the flow in a high-pressure, advanced-concept fuel injector at pressures thus far reaching 12 bar (12 atm). This technique offers a complementary method to the existing two- and three-dimensional imaging methods used, such as planar laser-induced fluorescence. Raman measurements benefit from the fact that the signal from each species is a linear function of its density, and the relative densities of all major species can be acquired simultaneously with good precision. The Raman method has the added potential to calibrate multidimensional measurements by providing an independent measurement of species number-densities at known points within the planar laser-induced fluorescence images. The visible Raman method is similar to an ultraviolet-Raman technique first tried in the same test facility (ref. 3). However, the visible method did not suffer from the ultraviolet technique's fuel-born polycyclic aromatic hydrocarbon fluorescence interferences.

Alterations in geometry, biomechanics, and mineral composition of juvenile rat femur induced by nonplanar PCB-155 and/or planar PCB-169.

PubMed

Brankovič, Jana; Jovanovski, Sašo; Jevnikar, Peter; Hofmeister, Alexander; Reininger-Gutmann, Birgit; Jan, Janja; Grošelj, Maja; Osredkar, Joško; Uršič, Matjaž; Fazarinc, Gregor; Pogačnik, Azra; Vrecl, Milka

2017-04-01

Exposure to widespread lipophilic and bioaccumulative polychlorinated biphenyls (PCBs) induces diverse biochemical and toxicological responses in various organs, including the bone. The aim of this study was to evaluate the changes in growth rate, geometry, serum, and bone biochemical parameters and biomechanics of juvenile rat femur induced by lactational exposure to nonplanar PCB-155 and planar PCB-169 individually and in combination. Fifteen lactating Wistar rats were divided into four groups (PCB-169, PCB-155, PCB-155+169, and control), and PCBs were administered intraperitoneally at different time points after delivery. Femurs from 22-day-old offspring were analyzed by microCT, three-point bending test and inductively coupled plasma-mass spectrometry (ICP-MS) to obtain data on bone geometry, biomechanics and mineral composition. The serum levels of calcium, phosphate and alkaline phosphatase were also determined. Lactational exposure to planar PCB-169 resulted in shorter and thinner femurs, reduced endosteal and periosteal perimeters, smaller total cross-sectional and medullary areas, and lowered serum bone marker levels and calcium levels in the bone, while femur mechanical properties were not significantly altered. The changes observed in the combination exposure (PCB-155+169) group were similar to those observed in the PCB-169 group but were less pronounced. In summary, our results demonstrate that alterations in lactationally exposed offspring were primarily induced by planar PCB-169. The milder outcome in the combined group suggested that the PCB-169-mediated toxic effects on the bone might be reduced by a nonplanar PCB-155 congener. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1135-1146, 2017. © 2016 Wiley Periodicals, Inc.

Inkjet-based adaptive planarization (Conference Presentation)

NASA Astrophysics Data System (ADS)

Singhal, Shrawan; Grigas, Michelle M.; Khusnatdinov, Niyaz; Sreenivasan, Srinivasan V.

2017-03-01

Planarization is a critical unit step in the lithography process because it enables patterning of surfaces with versatile pattern density without compromising on the stringent planarity and depth-of-focus requirements. In addition to nanoscale pattern density variation, parasitics such as pre-existing wafer topography, can corrupt the desired process output after planarization. The topography of any surface can be classified in three broad categories, depending upon the amplitude and spatial wavelength of the same [1], [2]: (i) nominal shape, (ii) nanotopography and (iii) roughness. The nominal shape is given by the largest spatial wavelengths, typically < 20mm. For spatial length scales of 1-20mm, height variations at this spatial wavelength range are classified as nanotopography. Roughness usually has lower spatial wavelengths. While the nominal shape of a substrate surface is usually decided by the nature of wafer preparation and the tooling and chucking infrastructure used in the same, roughness is usually mitigated by standard polishing techniques. It is the intermediate nanotopography that is probably the most critical surface topography parameter. This is because most traditional polishing techniques cannot selectively address pre-existing substrate topography, without introducing a parasitic signature at the scale of nanotopography. Moreover, fields with pattern density variation typically also have length scales that are commensurate with nanotopography. It is thus instructive to summarize existing planarization technology to understand current limitations. Spin on Glass and Etch back is one technique used for micron scale device manufacturing [3]. As the name implies, a glass dielectric is spin-coated on the substrate followed by etching in a chemistry that ensures equal etching rates for both the sacrificial glass and the underlying film or substrate material. Photoresists may also be used instead of glass. However, the global planarity that can be achieved by this technique is limited. Also, planarization over a large isolated topographical feature has been studied for the reverse-tone Jet-and-Flash Imprint Lithography process, also known as JFIL-R [4]. This relies on surface tension and capillary effects to smoothen a spin-coated Si containing film that can be etched to obtain a smooth profile. To meet the stringent requirement of planarity in submicron device technologies Chemical Mechanical Planarization (CMP) is the most widely used planarization technology [5], [6]. It uses a combination of abrasive laden chemical slurry and a mechanical pad for achieving planar profiles. The biggest concern with CMP is the dependence of material removal rate on the pattern density of material, leading to the formation of a step between the high density and low-density. The step shows up as a long-range thickness variation in the planarized film, similar in scale to pre-existing substrate topography that should have been polished away. Preventive techniques like dummy fill and patterned resist can be used to reduce the variation in pattern density. These techniques increase the complexity of the planarization process and significantly limit the device design flexibility. Contact Planarization (CP) has also been reported as an alternative to the CMP processing [7], [8]. A substrate is spin coated with a photo curable material and pre baked to remove residual solvent. An ultra-flat surface or an optical flat is pressed on the spin-coated wafer. The material is forced to reflow. Pressure is used to spread out material evenly and achieve global planarization. The substrate is then exposed to UV radiation to harden the photo curable material. Although attractive, this process is not adaptive as it does not account for differences in surface topography of the wafer and the optical flat, nor can it address all the parasitics that arise during the process itself. The optical flat leads to undesirable planarization of even the substrate nominal shape and nanotopography, which corrupts the final film thickness profile. Hence, it becomes extremely difficult to eliminate this signature to a desirable extent without introducing other parasitic signatures. An example of this is shown in Figure 1. In this paper, a novel adaptive planarization process has been presented that potentially addresses the problems associated with planarization of varying pattern density, even in the presence of pre-existing substrate topography [9]. This process is called Inkjet-enabled Adaptive Planarization (IAP). The IAP process uses an inverse optimization scheme, built around a validated fluid mechanics-based forward model [10], that takes the pre-existing substrate topography and pattern layout as inputs. It then generates an inkjet drop pattern with a material distribution that is correlated with the desired planarization film profile. This allows a contiguous film to be formed with the desired thickness variation to cater to the topography and any parasitic signatures caused by the pattern layout. This film is formed by the coercing action of a compliant superstrate, which forces the drops to spread and merge and eliminates any bubble trapping. Then, the film is cured using blanket UV exposure and the superstrate separated to reveal the desired planarized film. The use of an inverse optimization algorithm allows substrate topography to be addressed adaptively. In other words, the algorithm can generate a drop pattern that does not disturb the pre-existing substrate topography substantially, but only caters to the pattern density variation. This process has potential advantages over other planarization techniques because of its adaptive nature. Hence, the IAP process can cater to substrates of varying topographies and pattern densities by changing the inkjetted material distribution, without any changes in hardware. The IAP process can also address pre-existing substrate topography selectively by conforming to the nominal shape while planarizing over the pattern layout. A schematic of the IAP process is shown in Figure 2. The goal of this paper is to present some preliminary results from the IAP process. A test pattern layout has been generated with the help of photolithography, and is shown in Figure 3. For the purpose of this trial, the nanoscale features have not been patterned, as it is expected that the planarization process will be blind to their presence. Thus, areas with nanoscale patterns have been patterned as a single feature of SiO2 with height equal to 100 nm. These features are adjacent to pattern-less areas, thus marking a drastic change in pattern density. As can be seen in Figure 4, the smallest length scale across which pattern density changes, is 70 microns. The goal of the IAP process is to be able to planarize this pattern with a film that conforms to pre-existing substrate topography. The targeted planarity of the film is 95% 3sigma, while the targeted film thickness at the tallest feature is less than 30 nm. In another trial, the inverse tone of the same layout will also be tested. This pattern has features of height equal to 100 nm where the previous pattern did not. The targeted metrics for the inverse layout are the same as the nominal layout.

Nonlinear optical properties of organic materials V; Proceedings of the 5th Meeting, San Diego, CA, July 22-24, 1992

NASA Astrophysics Data System (ADS)

Williams, David J.

The present volume on nonlinear optical properties of organic materials discusses organic nonlinear optics, polymers for nonlinear optics, characterization of nonlinear properties, photorefractive and second-order materials, harmonic generation in organic materials, and devices and applications. Particular attention is given to organic semiconductor-doped polymer glasses as novel nonlinear media, heterocyclic nonlinear optical materials, loss measurements in electrooptic polymer waveguides, the phase-matched second-harmonic generation in planar waveguides, electrooptic measurements in poled polymers, transient effects in spatial light modulation by nonlinearity-absorbing molecules, the electrooptic effects in organic single crystals, surface acoustic wave propagation in an organic nonlinear optical crystal, nonlinear optics of astaxanthin thin films; and advanced high-temperature polymers for integrated optical waveguides. (No individual items are abstracted in this volume)

Single-mode glass waveguide technology for optical interchip communication on board level

NASA Astrophysics Data System (ADS)

Brusberg, Lars; Neitz, Marcel; Schröder, Henning

2012-01-01

The large bandwidth demand in long-distance telecom networks lead to single-mode fiber interconnects as result of low dispersion, low loss and dense wavelength multiplexing possibilities. In contrast, multi-mode interconnects are suitable for much shorter lengths up to 300 meters and are promising for optical links between racks and on board level. Active optical cables based on multi-mode fiber links are at the market and research in multi-mode waveguide integration on board level is still going on. Compared to multi-mode, a single-mode waveguide has much more integration potential because of core diameters of around 20% of a multi-mode waveguide by a much larger bandwidth. But light coupling in single-mode waveguides is much more challenging because of lower coupling tolerances. Together with the silicon photonics technology, a single-mode waveguide technology on board-level will be the straight forward development goal for chip-to-chip optical interconnects integration. Such a hybrid packaging platform providing 3D optical single-mode links bridges the gap between novel photonic integrated circuits and the glass fiber based long-distance telecom networks. Following we introduce our 3D photonic packaging approach based on thin glass substrates with planar integrated optical single-mode waveguides for fiber-to-chip and chip-to-chip interconnects. This novel packaging approach merges micro-system packaging and glass integrated optics. It consists of a thin glass substrate with planar integrated singlemode waveguide circuits, optical mirrors and lenses providing an integration platform for photonic IC assembly and optical fiber interconnect. Thin glass is commercially available in panel and wafer formats and characterizes excellent optical and high-frequency properties. That makes it perfect for microsystem packaging. The paper presents recent results in single-mode waveguide technology on wafer level and waveguide characterization. Furthermore the integration in a hybrid packaging process and design issues are discussed.

Advanced optic fabrication using ultrafast laser radiation

NASA Astrophysics Data System (ADS)

Taylor, Lauren L.; Qiao, Jun; Qiao, Jie

2016-03-01

Advanced fabrication and finishing techniques are desired for freeform optics and integrated photonics. Methods including grinding, polishing and magnetorheological finishing used for final figuring and polishing of such optics are time consuming, expensive, and may be unsuitable for complex surface features while common photonics fabrication techniques often limit devices to planar geometries. Laser processing has been investigated as an alternative method for optic forming, surface polishing, structure writing, and welding, as direct tuning of laser parameters and flexible beam delivery are advantageous for complex freeform or photonics elements and material-specific processing. Continuous wave and pulsed laser radiation down to the nanosecond regime have been implemented to achieve nanoscale surface finishes through localized material melting, but the temporal extent of the laser-material interaction often results in the formation of a sub-surface heat affected zone. The temporal brevity of ultrafast laser radiation can allow for the direct vaporization of rough surface asperities with minimal melting, offering the potential for smooth, final surface quality with negligible heat affected material. High intensities achieved in focused ultrafast laser radiation can easily induce phase changes in the bulk of materials for processing applications. We have experimentally tested the effectiveness of ultrafast laser radiation as an alternative laser source for surface processing of monocrystalline silicon. Simulation of material heating associated with ultrafast laser-material interaction has been performed and used to investigate optimized processing parameters including repetition rate. The parameter optimization process and results of experimental processing will be presented.

Fast Response and Spontaneous Alignment in Liquid Crystals Doped with 12-Hydroxystearic Acid Gelators

PubMed Central

Lin, Hui-Chi; Wang, Chih-Hung; Wang, Jyun-Kai; Tsai, Sheng-Feng

2018-01-01

The spontaneous vertical alignment of liquid crystals (LCs) in gelator (12-hydroxystearic acid)-doped LC cells was studied. Gelator-induced alignment can be used in both positive and negative LC cells. The electro-optical characteristics of the gelator-doped negative LC cell were similar to those of an LC cell that contained a vertically aligned (VA) host. The rise time of the gelator-doped LC cell was two orders of magnitude shorter than that of the VA host LC cell. The experimental results indicate that the gelator-induced vertical alignment of LC molecules occurred not only on the surface of the indium tin oxide (ITO) but also on the homogeneous alignment layer. Various LC alignments (planar, hybrid, multistable hybrid, and vertical alignments) were achieved by modulating the doped gelator concentrations. The multistable characteristic of LCs doped with the gelator is also presented. The alignment by doping with a gelator reduces the manufacturing costs and provides a means of fabricating fast-responding, flexible LC displays using a low-temperature process. PMID:29735937

At grade optical crossover for monolithic optial circuits

NASA Technical Reports Server (NTRS)

Jamieson, Robert S. (Inventor)

1983-01-01

Planar optical circuits may be made to cross through each other, (thus eliminating extra steps required to fabricate elevated, nonintersecting crossovers) by control of the dimensions of the crossing light conductors (10, 12) to be significantly greater than d=0.89.lambda. and the angle of crossing as nearly 90.degree. as conveniently possible. A light trap may be provided just ahead of the intersection to trap any light being reflected in the source conductor at angles greater than about 45.degree.. The light trap may take the form of triangular shaped portions (16a, 16b) on each side of the source conductor with the far side of the triangular portion receiving incident light at an angle so that incident light will be reflected to the other side, or it may take the form of windows (18a, 18b) in place of the triangular portions. Planar optical circuit boards (21-23) may be fabricated and stacked to form a keyboard (20) with intersecting conductors (26-29) and keyholes (0-9) where conductors merge at the broad side of the circuit boards. These keyholes may be prearranged to form an array or matrix of keyholes.

Bio-inspired hemispherical compound eye camera

NASA Astrophysics Data System (ADS)

Xiao, Jianliang; Song, Young Min; Xie, Yizhu; Malyarchuk, Viktor; Jung, Inhwa; Choi, Ki-Joong; Liu, Zhuangjian; Park, Hyunsung; Lu, Chaofeng; Kim, Rak-Hwan; Li, Rui; Crozier, Kenneth B.; Huang, Yonggang; Rogers, John A.

2014-03-01

Compound eyes in arthropods demonstrate distinct imaging characteristics from human eyes, with wide angle field of view, low aberrations, high acuity to motion and infinite depth of field. Artificial imaging systems with similar geometries and properties are of great interest for many applications. However, the challenges in building such systems with hemispherical, compound apposition layouts cannot be met through established planar sensor technologies and conventional optics. We present our recent progress in combining optics, materials, mechanics and integration schemes to build fully functional artificial compound eye cameras. Nearly full hemispherical shapes (about 160 degrees) with densely packed artificial ommatidia were realized. The number of ommatidia (180) is comparable to those of the eyes of fire ants and bark beetles. The devices combine elastomeric compound optical elements with deformable arrays of thin silicon photodetectors, which were fabricated in the planar geometries and then integrated and elastically transformed to hemispherical shapes. Imaging results and quantitative ray-tracing-based simulations illustrate key features of operation. These general strategies seem to be applicable to other compound eye devices, such as those inspired by moths and lacewings (refracting superposition eyes), lobster and shrimp (reflecting superposition eyes), and houseflies (neural superposition eyes).

Graphene as transmissive electrodes and aligning layers for liquid-crystal-based electro-optic devices.

PubMed

Basu, Rajratan; Shalov, Samuel A

2017-07-01

In a conventional liquid crystal (LC) cell, polyimide layers are used to align the LC homogeneously in the cell, and transmissive indium tin oxide (ITO) electrodes are used to apply the electric field to reorient the LC along the field. It is experimentally presented here that monolayer graphene films on the two glass substrates can function concurrently as the LC aligning layers and the transparent electrodes to fabricate an LC cell, without using the conventional polyimide and ITO substrates. This replacement can effectively decrease the thickness of all the alignment layers and electrodes from about 100 nm to less than 1 nm. The interaction between LC and graphene through π-π electron stacking imposes a planar alignment on the LC in the graphene-based cell-which is verified using a crossed polarized microscope. The graphene-based LC cell exhibits an excellent nematic director reorientation process from planar to homeotropic configuration through the application of an electric field-which is probed by dielectric and electro-optic measurements. Finally, it is shown that the electro-optic switching is significantly faster in the graphene-based LC cell than in a conventional ITO-polyimide LC cell.

Performance of Planar-Waveguide External Cavity Laser for Precision Measurements

NASA Technical Reports Server (NTRS)

Numata, Kenji; Camp, Jordan; Krainak, Michael A.; Stolpner, Lew

2010-01-01

A 1542-nm planar-waveguide external cavity laser (PW-ECL) is shown to have a sufficiently low level of frequency and intensity noise to be suitable for precision measurement applications. The frequency noise and intensity noise of the PW-ECL was comparable or better than the nonplanar ring oscillator (NPRO) and fiber laser between 0.1 mHz to 100 kHz. Controllability of the PW-ECL was demonstrated by stabilizing its frequency to acetylene (13C2H2) at 10(exp -13) level of Allan deviation. The PW-ECL also has the advantage of the compactness of a standard butterfly package, low cost, and a simple design consisting of a semiconductor gain media coupled to a planar-waveguide Bragg reflector. These features would make the PW-ECL suitable for precision measurements, including compact optical frequency standards, space lidar, and space interferometry

Planar-integrated single-crystalline perovskite photodetectors

PubMed Central

Saidaminov, Makhsud I.; Adinolfi, Valerio; Comin, Riccardo; Abdelhady, Ahmed L.; Peng, Wei; Dursun, Ibrahim; Yuan, Mingjian; Hoogland, Sjoerd; Sargent, Edward H.; Bakr, Osman M.

2015-01-01

Hybrid perovskites are promising semiconductors for optoelectronic applications. However, they suffer from morphological disorder that limits their optoelectronic properties and, ultimately, device performance. Recently, perovskite single crystals have been shown to overcome this problem and exhibit impressive improvements: low trap density, low intrinsic carrier concentration, high mobility, and long diffusion length that outperform perovskite-based thin films. These characteristics make the material ideal for realizing photodetection that is simultaneously fast and sensitive; unfortunately, these macroscopic single crystals cannot be grown on a planar substrate, curtailing their potential for optoelectronic integration. Here we produce large-area planar-integrated films made up of large perovskite single crystals. These crystalline films exhibit mobility and diffusion length comparable with those of single crystals. Using this technique, we produced a high-performance light detector showing high gain (above 104 electrons per photon) and high gain-bandwidth product (above 108 Hz) relative to other perovskite-based optical sensors. PMID:26548941

Equivalent isotropic scattering formulation for transient short-pulse radiative transfer in anisotropic scattering planar media.

PubMed

Guo, Z; Kumar, S

2000-08-20

An isotropic scaling formulation is evaluated for transient radiative transfer in a one-dimensional planar slab subject to collimated and/or diffuse irradiation. The Monte Carlo method is used to implement the equivalent scattering and exact simulations of the transient short-pulse radiation transport through forward and backward anisotropic scattering planar media. The scaled equivalent isotropic scattering results are compared with predictions of anisotropic scattering in various problems. It is found that the equivalent isotropic scaling law is not appropriate for backward-scattering media in transient radiative transfer. Even for an optically diffuse medium, the differences in temporal transmittance and reflectance profiles between predictions of backward anisotropic scattering and equivalent isotropic scattering are large. Additionally, for both forward and backward anisotropic scattering media, the transient equivalent isotropic results are strongly affected by the change of photon flight time, owing to the change of flight direction associated with the isotropic scaling technique.

Imaging trypsin activity through changes in the orientation of liquid crystals coupled to the interactions between a polyelectrolyte and a phospholipid layer.

PubMed

Hu, Qiong-Zheng; Jang, Chang-Hyun

2012-03-01

In this study, we developed a new type of liquid crystal (LC)-based sensor for the real-time and label-free monitoring of enzymatic activity through changes in the orientation of LCs coupled to the interactions between polyelectrolyte and phospholipid. The LCs changed from dark to bright after an aqueous solution of poly-l-lysine (PLL) was transferred onto a self-assembled monolayer of the phospholipid, dioleoyl-sn-glycero-3-phospho-rac-(1-glycerol) sodium salt (DOPG), at the aqueous/LC interface. Interactions between the positively charged PLL and the negatively charged DOPG drove the reorganization of the phospholipid membrane, which induced an orientational transition in the LCs from a homeotropic to planar state. Since the serine endopeptidase trypsin can enzymatically catalyze the hydrolysis of PLL, the dark-to-bright shift in the optical response was not observed after transferring a mixed solution of PLL and trypsin onto the DOPG-decorated LC interface, indicating that no orientational transitions in the LCs occurred. However, the optical response from dark to bright was observed when the mixture in the optical cell was replaced by an aqueous solution of PLL. Control experiments with trypsin or an aqueous mixture of PLL and deactivated trypsin further confirmed the feasibility of this approach. The detection limit of trypsin was determined to be ~1 μg/mL. This approach holds great promise for use in the development of LC-based sensors for the detection of enzymatic reactions in cases where the biological polyelectrolyte substrates of enzymes could disrupt the organization of the membrane and induce orientational transitions of LCs at the aqueous/LC interface. © 2012 American Chemical Society

Simulations of absorption spectra of conjugated oligomers: role of planar conformation and aggregation in condensed phase

NASA Astrophysics Data System (ADS)

Yuan, Xiang-Ai; Wen, Jin; Zheng, Dong; Ma, Jing

2018-04-01

This Review highlights the structure/property relationship underlying the morphology modulation through various factors towards the exploration of light-absorbing materials for efficient utilisation of solar power. Theoretical study using a combination of molecular dynamics imulations and the time-dependent density functional theory demonstrated that the planarity plays an important role in tuning spectral properties of oligomer aggregates. The aggregation-induced blue-shift in absorption spectra of oligothiophenes and the red-shift for oligofluorenols were rationalised in a unified way from the reduced (and increased) content of planar conformations in molecular aggregates. The planarity versus non-planarity of oligomers can be modulated by introduction of alkyl side chain or steric bulky substituents. The substitution with various groups in the ortho-position of azobenzene leads to the distorted backbone, breaking symmetry, and hence the red-shift in spectra, expanding the application in biological systems with visible light absorption. The donor-acceptor substituent groups in conjugated oligomers can increase the degree of planarity, electron delocalisation and polarisation, and charge separation, giving rise to the red-shift in spectra and enhancement in polarisability and charge mobility for device applications. The solvent dependent and pH-sensitive properties and intramolecular hydrogen bonds also caused the shift of absorption spectra with the appearance of planar conformers.

An acousto-optic sensor based on resonance grating waveguide structure

PubMed Central

Xie, Antonio Jou; Song, Fuchuan; Seo, Sang-Woo

2014-01-01

This paper presents an acousto-optic (AO) sensor based on resonance grating waveguide structure. The sensor is fabricated using elastic polymer materials to achieve a good sensitivity to ultrasound pressure waves. Ultrasound pressure waves modify the structural parameters of the sensor and result in the optical resonance shift of the sensor. This converts into a light intensity modulation. A commercial ultrasound transducer at 20 MHz is used to characterize a fabricated sensor and detection sensitivity at different optical source wavelength within a resonance spectrum is investigated. Practical use of the sensor at a fixed optical source wavelength is presented. Ultimately, the geometry of the planar sensor structure is suitable for two-dimensional, optical pressure imaging applications such as pressure wave detection and mapping, and ultrasound imaging. PMID:25045203

Projection moire for remote contour analysis

NASA Technical Reports Server (NTRS)

Doty, J. L.

1983-01-01

Remote projection and viewing of moire contours are examined analytically for a system employing separate projection and viewing optics, with specific attention paid to the practical limitations imposed by the optical systems. It is found that planar contours are possible only when the optics are telecentric (exit pupil at infinity) but that the requirement for spatial separability of the contour fringes from extraneous fringes is independent of the specific optics and is a function only of the angle separating the two optic axes. In the nontelecentric case, the contour separation near the object is unchanged from that of the telecentric case, although the contours are distorted into low-eccentricity (near-circular) ellipses. Furthermore, the minimum contour spacing is directly related to the depth of focus through the resolution of the optics.

Polymeric PLC-type thermo-optic optical attenuator fabricated by UV imprint technique

NASA Astrophysics Data System (ADS)

Kim, Jin Tae; Choi, Choon-Gi

2006-01-01

A planar lightwave circuit-type polymer thermo-optic optical attenuator was fabricated via a UV imprint technique. In order to reduce the step for filling of cores and minimize the detrimental residual slab waveguide, convex ridge-type micro cores for guidance of light were defined with an accuracy of ±0.5 μm on the under-clad by a single step of imprinting. The voltage-controlled polymer optical attenuator showed 30-dB attenuation with 80-mW electrical input power at a wavelength of 1.55 μm. The rise and fall times are less than 5 ms. It displays about 0.2- and 1-dB polarization dependence at 0- and 10-dB attenuations, respectively.

Fabricating binary optics: An overview of binary optics process technology

NASA Technical Reports Server (NTRS)

Stern, Margaret B.

1993-01-01

A review of binary optics processing technology is presented. Pattern replication techniques have been optimized to generate high-quality efficient microoptics in visible and infrared materials. High resolution optical photolithography and precision alignment is used to fabricate maximally efficient fused silica diffractive microlenses at lambda = 633 nm. The degradation in optical efficiency of four-phase-level fused silica microlenses resulting from an intentional 0.35 micron translational error has been systematically measured as a function of lens speed (F/2 - F/60). Novel processes necessary for high sag refractive IR microoptics arrays, including deep anisotropic Si-etching, planarization of deep topography and multilayer resist techniques, are described. Initial results are presented for monolithic integration of photonic and microoptic systems.

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.

Chemical, biochemical, and environmental fiber sensors III; Proceedings of the Meeting, Boston, MA, Sept. 4, 5, 1991

NASA Astrophysics Data System (ADS)

Lieberman, Robert A.

Various papers on chemical, biochemical, and environmental fiber sensors are presented. Individual topics addressed include: fiber optic pressure sensor for combustion monitoring and control, viologen-based fiber optic oxygen sensors, renewable-reagent fiber optic sensor for ocean pCO2, transition metal complexes as indicators for a fiber optic oxygen sensor, fiber optic pH measurements using azo indicators, simple reversible fiber optic chemical sensors using solvatochromic dyes, totally integrated optical measuring sensors, integrated optic biosensor for environmental monitoring, radiation dosimetry using planar waveguide sensors, optical and piezoelectric analysis of polymer films for chemical sensor characterization, source polarization effects in an optical fiber fluorosensor, lens-type refractometer for on-line chemical analysis, fiber optic hydrocarbon sensor system, chemical sensors for environmental monitoring, optical fibers for liquid-crystal sensing and logic devices, suitability of single-mode fluoride fibers for evanescent-wave sensing, integrated modules for fiber optic sensors, optoelectronic sensors based on narrowband A3B5 alloys, fiber Bragg grating chemical sensor.

Experimental investigation of non-planar sheared outboard wing planforms

NASA Technical Reports Server (NTRS)

Naik, D. A.; Ostowari, C.

1988-01-01

The outboard planforms of wings have been found to be of prime importance in studies of induced drag reduction. This conclusion is based on an experimental and theoretical study of the aerodynamic characteristics of planar and nonplanar outboard wing forms. Six different configurations; baseline rectangular, planar sheared, sheared with dihedral, sheared with anhedral, rising arc, and drooping arc were investigated for two different spans. Span efficiencies as much as 20 percent greater than baseline can be realized with nonplanar wing forms. Optimization studies show that this advantage can be achieved along with a bending moment benefit. Parasite drag and lateral stability estimations were not included in the analysis.

Solid State Research.

DTIC Science & Technology

1983-02-15

0.1 J/cm2 at 520 us, and Pulse Repetition Rate Was 10 Hs. 33 2-8 Nomarski Optical Micrograph of a Photodeposited Waveguide in LtNbO3 After Indiffusion...evaluate the interferometric array, the technique shown in Fig. 1-5 was used. With the two-mirror system shown, an incident planar wavefront could be...t- -’-, ,i- 1 0 110 - Fig. 2-8. Nomarski optical micrograph of a photodeposited waveguide in LiNbO3 after indiffusion. Small-scale divisions

Waveguide structures in anisotropic nonlinear crystals

NASA Astrophysics Data System (ADS)

Li, Da; Hong, Pengda; Meissner, Helmuth E.

2017-02-01

We report on the design and manufacturing parameters of waveguiding structures of anisotropic nonlinear crystals that are employed for harmonic conversions, using Adhesive-Free Bonding (AFB®). This technology enables a full range of predetermined refractive index differences that are essential for the design of single mode or low-mode propagation with high efficiency in anisotropic nonlinear crystals which in turn results in compact frequency conversion systems. Examples of nonlinear optical waveguides include periodically bonded walk-off corrected nonlinear optical waveguides and periodically poled waveguide components, such as lithium triborate (LBO), beta barium borate (β-BBO), lithium niobate (LN), potassium titanyl phosphate (KTP), zinc germanium phosphide (ZGP) and silver selenogallate (AGSE). Simulation of planar LN waveguide shows that when the electric field vector E lies in the k-c plane, the power flow is directed precisely along the propagation direction, demonstrating waveguiding effect in the planar waveguide. Employment of anisotropic nonlinear optical waveguides, for example in combination with AFB® crystalline fiber waveguides (CFW), provides access to the design of a number of novel high power and high efficiency light sources spanning the range of wavelengths from deep ultraviolet (as short as 200 nm) to mid-infrared (as long as about 18 μm). To our knowledge, the technique is the only generally applicable one because most often there are no compatible cladding crystals available to nonlinear optical cores, especially not with an engineer-able refractive index difference and large mode area.

Sinusoidal nanotextures for light management in silicon thin-film solar cells.

PubMed

Köppel, G; Rech, B; Becker, C

2016-04-28

Recent progresses in liquid phase crystallization enabled the fabrication of thin wafer quality crystalline silicon layers on low-cost glass substrates enabling conversion efficiencies up to 12.1%. Because of its indirect band gap, a thin silicon absorber layer demands for efficient measures for light management. However, the combination of high quality crystalline silicon and light trapping structures is still a critical issue. Here, we implement hexagonal 750 nm pitched sinusoidal and pillar shaped nanostructures at the sun-facing glass-silicon interface into 10 μm thin liquid phase crystallized silicon thin-film solar cell devices on glass. Both structures are experimentally studied regarding their optical and optoelectronic properties. Reflection losses are reduced over the entire wavelength range outperforming state of the art anti-reflective planar layer systems. In case of the smooth sinusoidal nanostructures these optical achievements are accompanied by an excellent electronic material quality of the silicon absorber layer enabling open circuit voltages above 600 mV and solar cell device performances comparable to the planar reference device. For wavelengths smaller than 400 nm and higher than 700 nm optical achievements are translated into an enhanced quantum efficiency of the solar cell devices. Therefore, sinusoidal nanotextures are a well-balanced compromise between optical enhancement and maintained high electronic silicon material quality which opens a promising route for future optimizations in solar cell designs for silicon thin-film solar cells on glass.

Integrated optical refractometer based on bend waveguide with air trench structure

NASA Astrophysics Data System (ADS)

Ryu, Jin Hwa; Park, Jaehoon; Kang, Chan-mo; Son, Youngdal; Do, Lee-Mi; Baek, Kyu-Ha

2015-07-01

This study proposed a novel optical sensor based on a refractometer integrating a bend waveguide and a trench structure. The optical sensor is a planar lightwave circuit (PLC) device involving a bend waveguide with maximum optical loss. A trench structure was aligned with the partially exposed core layer's sidewall of the bend waveguide, providing a quantitative measurement condition. The insertion losses of the proposed 1 x 2 single-mode optical splitter-type sensor were 4.38 dB and 8.67 dB for the reference waveguide and sensing waveguide, respectively, at a wavelength of 1,550 nm. The optical loss of the sensing waveguide depends on the change in the refractive index of the material in contact with the trench, but the reference waveguide had stable optical propagating characteristic regardless of the variations of the refractive index.

Development of Nomarski microscopy for quantitative determination of surface topography

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

Hartman, J. S.; Gordon, R. L.; Lessor, D. L.

1979-01-01

The use of Nomarski differential interference contrast (DIC) microscopy has been extended to provide nondestructive, quantitative analysis of a sample's surface topography. Theoretical modeling has determined the dependence of the image intensity on the microscope's optical components, the sample's optical properties, and the sample's surface orientation relative to the microscope. Results include expressions to allow the inversion of image intensity data to determine sample surface slopes. A commercial Nomarski system has been modified and characterized to allow the evaluation of the optical model. Data have been recorded with smooth, planar samples that verify the theoretical predictions.

32 bit digital optical computer - A hardware update

NASA Technical Reports Server (NTRS)

Guilfoyle, Peter S.; Carter, James A., III; Stone, Richard V.; Pape, Dennis R.

1990-01-01

Such state-of-the-art devices as multielement linear laser diode arrays, multichannel acoustooptic modulators, optical relays, and avalanche photodiode arrays, are presently applied to the implementation of a 32-bit supercomputer's general-purpose optical central processing architecture. Shannon's theorem, Morozov's control operator method (in conjunction with combinatorial arithmetic), and DeMorgan's law have been used to design an architecture whose 100 MHz clock renders it fully competitive with emerging planar-semiconductor technology. Attention is given to the architecture's multichannel Bragg cells, thermal design and RF crosstalk considerations, and the first and second anamorphic relay legs.

Spectrum of classes of point emitters of electromagnetic wave fields.

PubMed

Castañeda, Román

2016-09-01

The spectrum of classes of point emitters has been introduced as a numerical tool suitable for the design, analysis, and synthesis of non-paraxial optical fields in arbitrary states of spatial coherence. In this paper, the polarization state of planar electromagnetic wave fields is included in the spectrum of classes, thus increasing its modeling capabilities. In this context, optical processing is realized as a filtering on the spectrum of classes of point emitters, performed by the complex degree of spatial coherence and the two-point correlation of polarization, which could be implemented dynamically by using programmable optical devices.

Electro-Optic Effect in Thin Films of a Dielectric and a Ferroelectric with Subwavelength Aluminum Grating

NASA Astrophysics Data System (ADS)

Blinov, L. M.; Lazarev, V. V.; Yudin, S. G.; Artemov, V. V.; Palto, S. P.; Gorkunov, M. V.

2018-01-01

The electro-optic effect in three nanoscale heterostructures, in each of which a thin layer of dielectric or ferroelectric material is inserted between two planar metal electrodes, has been studied. Each structure has one aluminum layer, containing a subwavelength grating with a period of 400 nm, contacting with either the glass substrate or air. The light transmission spectra of structures with subwavelength grating contain characteristic plasmon dips. Short external-voltage pulses affect the change in the refractive index of the corresponding active layer. Significant values of these changes may be useful for designing optical modulators.

Polysilicon planarization and plug recess etching in a decoupled plasma source chamber using two endpoint techniques

NASA Astrophysics Data System (ADS)

Kaplita, George A.; Schmitz, Stefan; Ranade, Rajiv; Mathad, Gangadhara S.

1999-09-01

The planarization and recessing of polysilicon to form a plug are processes of increasing importance in silicon IC fabrication. While this technology has been developed and applied to DRAM technology using Trench Storage Capacitors, the need for such processes in other IC applications (i.e. polysilicon studs) has increased. Both planarization and recess processes usually have stringent requirements on etch rate, recess uniformity, and selectivity to underlying films. Additionally, both processes generally must be isotropic, yet must not expand any seams that might be present in the polysilicon fill. These processes should also be insensitive to changes in exposed silicon area (pattern factor) on the wafer. A SF6 plasma process in a polysilicon DPS (Decoupled Plasma Source) reactor has demonstrated the capability of achieving the above process requirements for both planarization and recess etch. The SF6 process in the decoupled plasma source reactor exhibited less sensitivity to pattern factor than in other types of reactors. Control of these planarization and recess processes requires two endpoint systems to work sequentially in the same recipe: one for monitoring the endpoint when blanket polysilicon (100% Si loading) is being planarized and one for monitoring the recess depth while the plug is being recessed (less than 10% Si loading). The planarization process employs an optical emission endpoint system (OES). An interferometric endpoint system (IEP), capable of monitoring lateral interference, is used for determining the recess depth. The ability of using either or both systems is required to make these plug processes manufacturable. Measuring the recess depth resulting from the recess process can be difficult, costly and time- consuming. An Atomic Force Microscope (AFM) can greatly alleviate these problems and can serve as a critical tool in the development of recess processes.

Planoconcave optical microresonator sensors for photoacoustic imaging: pushing the limits of sensitivity (Conference Presentation)

NASA Astrophysics Data System (ADS)

Guggenheim, James A.; Zhang, Edward Z.; Beard, Paul C.

2016-03-01

Most photoacoustic scanners use piezoelectric detectors but these have two key limitations. Firstly, they are optically opaque, inhibiting backward mode operation. Secondly, it is difficult to achieve adequate detection sensitivity with the small element sizes needed to provide near-omnidirectional response as required for tomographic imaging. Planar Fabry-Perot (FP) ultrasound sensing etalons can overcome both of these limitations and have proved extremely effective for superficial (<1cm) imaging applications. To achieve small element sizes (<100μm), the etalon is illuminated with a focused laser beam. However, this has the disadvantage that beam walk-off due to the divergence of the beam fundamentally limits the etalon finesse and thus sensitivity - in essence, the problem is one of insufficient optical confinement. To overcome this, novel planoconcave micro-resonator sensors have been fabricated using precision ink-jet printed polymer domes with curvatures matching that of the laser wavefront. By providing near-perfect beam confinement, we show that it is possible to approach the maximum theoretical limit for finesse (f) imposed by the etalon mirror reflectivities (e.g. f=400 for R=99.2% in contrast to a typical planar sensor value of f<50). This yields an order of magnitude increase in sensitivity over a planar FP sensor with the same acoustic bandwidth. Furthermore by eliminating beam walk-off, viable sensors can be made with significantly greater thickness than planar FP sensors. This provides an additional sensitivity gain for deep tissue imaging applications such as breast imaging where detection bandwidths in the low MHz can be tolerated. For example, for a 250 μm thick planoconcave sensor with a -3dB bandwidth of 5MHz, the measured NEP was 4 Pa. This NEP is comparable to that provided by mm scale piezoelectric detectors used for breast imaging applications but with more uniform frequency response characteristics and an order-of-magnitude smaller element size. Following previous proof-of-concept work, several important advances towards practical application have been made. A family of sensors with bandwidths ranging from 3MHz to 20MHz have been fabricated and characterised. A novel interrogation scheme based on rapid wavelength sweeping has been implemented in order to avoid previously encountered instability problems due to self-heating. Finally, a prototype microresonator based photoacoustic scanner has been developed and applied to the problem of deep-tissue (>1cm) photoacoustic imaging in vivo. Imaging results for second generation microresonator sensors (with R = 99.5% and thickness up to ~800um) are compared to the best achievable with the planar FP sensors and piezoelectric receivers.

Cr:ZnSe planar waveguide mid-IR laser

NASA Astrophysics Data System (ADS)

Willimas, J. E.; Martyshkin, D. V.; Fedorov, V. V.; Moskalev, I. S.; Camata, R. P.; Mirov, S. B.

2011-02-01

Middle infrared (mid-IR) chromium-doped zinc selenide (Cr:ZnSe) bulk lasers have attracted a lot of attention due to their unique combination of optical and laser properties facilitating a wide range of potential scientific, industrial, and medical applications. Utilization of thin film waveguide geometry enabling good thermal management and control of beam quality is a viable pathway for compact chip-integrated optical laser design. Cr:ZnSe thin films are also promising as saturable absorbers and mode-lockers of the cavities of solid state lasers operating over 1.3-2.1 μm. We recently reported the first successful demonstration of mid-IR Cr:ZnSe planar waveguide lasing at 2.6 μm under gain-switched short-pulse (5 ns) 1.56 μm excitation as well as the passive Q-switching of the cavity of a fiber-pumped Er:YAG laser operating at 1645 nm using a highly doped Cr:ZnSe thin film. PLD grown Cr:ZnSe waveguide were fabricated on sapphire substrates (Cr:ZnSe/sapphire) with chromium concentration of 1018-1019 cm-3. Further development of mid-IR lasing in the Cr:ZnSe planar waveguide under continuous wave excitation were investigated. In addition, deposition of Cr:ZnSe-based thin film structures on n-type GaAs substrates were also investigated for possible mid-IR electroluminescence.

APTAMER CAPTURE AND OPTICAL INTERFEROMETRIC DETECTION OF CYANOBACTERIAL TOXINS

EPA Science Inventory

Cyanobacterial toxins have been identified as a health risk in source and finished waters passing through drinking water utilities in the United States. In this project, a rapid, sensitive and field usable sensor based on an aptamer modified planar waveguide interferometric se...

Optimization of planar self-collimating photonic crystals.

PubMed

Rumpf, Raymond C; Pazos, Javier J

2013-07-01

Self-collimation in photonic crystals has received a lot of attention in the literature, partly due to recent interest in silicon photonics, yet no performance metrics have been proposed. This paper proposes a figure of merit (FOM) for self-collimation and outlines a methodical approach for calculating it. Performance metrics include bandwidth, angular acceptance, strength, and an overall FOM. Two key contributions of this work include the performance metrics and identifying that the optimum frequency for self-collimation is not at the inflection point. The FOM is used to optimize a planar photonic crystal composed of a square array of cylinders. Conclusions are drawn about how the refractive indices and fill fraction of the lattice impact each of the performance metrics. The optimization is demonstrated by simulating two spatially variant self-collimating photonic crystals, where one has a high FOM and the other has a low FOM. This work gives optical designers tremendous insight into how to design and optimize robust self-collimating photonic crystals, which promises many applications in silicon photonics and integrated optics.

Crystallographic Orientation Identification in Multicrystalline Silicon Wafers Using NIR Transmission Intensity

NASA Astrophysics Data System (ADS)

Skenes, Kevin; Kumar, Arkadeep; Prasath, R. G. R.; Danyluk, Steven

2018-02-01

Near-infrared (NIR) polariscopy is a technique used for the non-destructive evaluation of the in-plane stresses in photovoltaic silicon wafers. Accurate evaluation of these stresses requires correct identification of the stress-optic coefficient, a material property which relates photoelastic parameters to physical stresses. The material stress-optic coefficient of silicon varies with crystallographic orientation. This variation poses a unique problem when measuring stresses in multicrystalline silicon (mc-Si) wafers. This paper concludes that the crystallographic orientation of silicon can be estimated by measuring the transmission of NIR light through the material. The transmission of NIR light through monocrystalline wafers of known orientation were compared with the transmission of NIR light through various grains in mc-Si wafers. X-ray diffraction was then used to verify the relationship by obtaining the crystallographic orientations of these assorted mc-Si grains. Variation of transmission intensity for different crystallographic orientations is further explained by using planar atomic density. The relationship between transmission intensity and planar atomic density appears to be linear.

Phase resolved near-field imaging of propagating waves in infrared tapered slot antennas

NASA Astrophysics Data System (ADS)

Florence, Louis A.; Kinzel, Edward C.; Olmon, Robert L.; Ginn, James C.; Raschke, Markus B.; Boreman, Glenn D.

2012-11-01

Tapered slot antennas (TSAs) consist of a planar non-resonant structure which couples incident radiation to a propagating waveguide mode. They are commonly used at microwave and radio frequencies because they are fundamentally broadband and have small profiles. Because of their planar layout and broadband response they have recently been scaled to infrared frequencies where they have advantages for sensing and energy harvesting. We use scattering-type scanning near-field optical microscopy (s-SNOM) to study the mode transformation of two types of TSA operating in the thermal infrared (λ0 = 10.6 μm) with respect to electric field amplitude and phase. The results agree well with simulation showing both the phase reversal across the tapered slot and the traveling of wave fronts along the tapered slot, yet they also reveal high sensitivity of device performance to inhomogeneities in the geometry or illumination. This study will aid future design and analysis of practical non-resonant antennas operating at optical and infrared frequencies.

Single-frequency Nd:YAG ring lasers with corner cube prism

NASA Astrophysics Data System (ADS)

Wu, Ke Ying; Yang, Su Hui; Zhao, Chang Ming; Wei, Guang Hui

2000-04-01

Kane and Byer reported the first monolithic non-planar miniature ring lasers in 1985. An intrinsic optical diode enforces unidirectional and hence single-frequency oscillation of this device. It has the advantages of compactness, reliability and high efficiency. We put forward another form of the non-planar ring lasers, in which the corner cube prism is the key element and the Nd:YAG crystal is used as a Porro prism to enclose the ring resonator. The phase shift due to the total internal reflections of the three differently orientated reflection planes of the corner cube prism, Faraday rotation in the Nd:YAG crystal placed in a magnetic field and the different output coupling in S and P polarization form an optical diode and enforce the single- frequency generating. A round trip analysis of the polarization properties of the resonator is made by the evaluation of Jones matrix. The results of our initial experiment are given in the paper.

Strong coupling between 0D and 2D modes in optical open microcavities

NASA Astrophysics Data System (ADS)

Trichet, A. A. P.; Dolan, P. R.; Smith, J. M.

2018-02-01

We present a study of the coupling between confined modes and continuum states in an open microcavity system. The confined states are the optical modes of a plano-concave Fabry-Pérot cavity while the continuum states are the propagating modes in a surrounding planar cavity. The length tunability of the open cavity system allows to study the evolution of localised modes as they are progressively deconfined and coupled to the propagating modes. We observe an anti-crossing between the confined and propagating modes proving that mode-mixing takes place in between these two families of modes, and identify 0D-2D mixed modes which exhibit reduced loss compared with their highly localised counterparts. For practical design, we investigate the details of the microcavity shape that can be used to engineer the degree of mode-mixing. This study discusses for the first time experimentally and theoretically how light confinement arises in planar micromirrors and is of interest for the realisation of chip-based extended microphotonics using open cavities.

Military microwaves '84; Proceedings of the Conference, London, England, October 24-26, 1984

NASA Astrophysics Data System (ADS)

The present conference on microwave frequency electronic warfare and military sensor equipment developments consider radar warning receivers, optical frequency spread spectrum systems, mobile digital communications troposcatter effects, wideband bulk encryption, long range air defense radars (such as the AR320, W-2000 and Martello), multistatic radars, and multimode airborne and interceptor radars. IR system and subsystem component topics encompass thermal imaging and active IR countermeasures, class 1 modules, and diamond coatings, while additional radar-related topics include radar clutter in airborne maritime reconnaissance systems, microstrip antennas with dual polarization capability, the synthesis of shaped beam antenna patterns, planar phased arrays, radar signal processing, radar cross section measurement techniques, and radar imaging and pattern analysis. Attention is also given to optical control and signal processing, mm-wave control technology and EW systems, W-band operations, planar mm-wave arrays, mm-wave monolithic solid state components, mm-wave sensor technology, GaAs monolithic ICs, and dielectric resonator and wideband tunable oscillators.

Thermal contribution of compact bone to intervening tissue-like media exposed to planar ultrasound

NASA Astrophysics Data System (ADS)

Moros, Eduardo G.; Novak, Petr; Straube, William L.; Kolluri, Prashant; Yablonskiy, Dmitriy A.; Myerson, Robert J.

2004-03-01

The presence of bone in the ultrasound beam path raises concerns, both in diagnostic and therapeutic applications, because significant temperature elevations may be induced at nearby soft tissue-bone interfaces due the facts that ultrasound is (i) highly absorbed in bone and (ii) reflected at soft tissue-bone interfaces in various degrees depending on angle of incidence. Consequently, in ultrasonic thermal therapy, the presence of bone in the ultrasound beam path is considered a major disadvantage and it is usually avoided. However, based on clinical experience and previous theoretical studies, we hypothesized that the presence of bone in superficial unfocused ultrasound hyperthermia can actually be exploited to induce more uniform and enhanced (with respect to the no-bone situation) temperature distributions in superficial target volumes. In particular, we hypothesize that the presence of underlying bone in superficial target volume enhances temperature elevation not only by additional direct power deposition from acoustic reflection, but also from thermal diffusion from the underlying bone. Here we report laboratory results that corroborate previous computational studies and strengthen the above-stated hypothesis. Three different temperature measurement techniques, namely, thermometric (using fibre-optic temperature probes), thermographic (using an infrared camera) and magnetic resonance imaging (using proton resonance frequency shifts), were used in high-power short-exposure, and in low-power extended-exposure, experiments using a 19 mm diameter planar transducer operating at 1.0 and 3.3 MHz (frequencies of clinical relevance). The measurements were performed on three technique-specific phantoms (with and without bone inclusions) and experimental set-ups that resembled possible superficial ultrasound hyperthermia clinical situations. Results from all three techniques were in general agreement and clearly showed that significantly higher heating rates (greater than fourfold) were induced in soft tissue-like phantom materials adjacent (within ~5 mm) to a bovine bone as compared to similar experiments without bone inclusions. For low-power long-exposure experiments, where thermal conduction effects are significant, the thermal impact of bone reached at distances >10 mm from the bone surface (upstream of the bone). Therefore, we hypothesize that underlying bone exposed to planar ultrasound hyperthermia creates a high-temperature thermal boundary at depth that compensates for beam attenuation, thus producing more uniform temperature distribution in the intervening tissue layers. With appropriate technology, this finding may lead to improved thermal doses in superficial treatment sites such as the chest wall and the head/neck.

Giant optical activity in quasi-2D planar nanostructures

NASA Astrophysics Data System (ADS)

Kuwata-Gonokami, Makoto; Saito, Nobuyoshi; Ino, Yusuke; Konishi, Kuniaki; Kauranen, Martti; Jefimovs, Konstantins; Vallius, Tuomas; Turunen, Jari; Svirko, Yuri P.

2006-01-01

Planar chirality can lead to interesting polarization effects whose interpretation has invoked possible violation of reciprocity and time reversality. We show that a quasi-two-dimensional array consisting of gold nanoparticles with no symmetry plane and having sub-wavelength periodicity and thickness exhibits giant specific rotation (~10 4 °/mm) at normal incidence. The rotation is the same for light incident on the front and back sides of the sample. Such reciprocity manifests three-dimensionality of the structure arising from the asymmetry of light-plasmon coupling at the air-metal and substrate-metal interfaces of the structure. The structures thus enable nanoscale polarization control but violate no symmetry principle.

Field of view of limitations in see-through HMD using geometric waveguides.

PubMed

DeHoog, Edward; Holmstedt, Jason; Aye, Tin

2016-08-01

Geometric waveguides are being integrated into head-mounted display (HMD) systems, where having see-through capability in a compact, lightweight form factor is required. We developed methods for determining the field of view (FOV) of such waveguide HMD systems and have analytically derived the FOV for waveguides using planar and curved geometries. By using real ray-tracing methods, we are able to show how the geometry and index of refraction of the waveguide, as well as the properties of the coupling optics, impact the FOV. Use of this analysis allows one to determine the maximum theoretical FOV of a planar or curved waveguide-based system.

An imaging system for PLIF/Mie measurements for a combusting flow

NASA Technical Reports Server (NTRS)

Wey, C. C.; Ghorashi, B.; Marek, C. J.; Wey, C.

1990-01-01

The equipment required to establish an imaging system can be divided into four parts: (1) the light source and beam shaping optics; (2) camera and recording; (3) image acquisition and processing; and (4) computer and output systems. A pulsed, Nd:YAG-pummped, frequency-doubled dye laser which can freeze motion in the flowfield is used for an illumination source. A set of lenses is used to form the laser beam into a sheet. The induced fluorescence is collected by an UV-enhanced lens and passes through an UV-enhanced microchannel plate intensifier which is optically coupled to a gated solid state CCD camera. The output of the camera is simultaneously displayed on a monitor and recorded on either a laser videodisc set of a Super VHS VCR. This videodisc set is controlled by a minicomputer via a connection to the RS-232C interface terminals. The imaging system is connected to the host computer by a bus repeater and can be multiplexed between four video input sources. Sample images from a planar shear layer experiment are presented to show the processing capability of the imaging system with the host computer.

First human Cerenkography

NASA Astrophysics Data System (ADS)

Spinelli, Antonello Enrico; Ferdeghini, Marco; Cavedon, Carlo; Zivelonghi, Emanuele; Calandrino, Riccardo; Fenzi, Alberto; Sbarbati, Andrea; Boschi, Federico

2013-02-01

Cerenkov luminescence imaging is an emerging optical preclinical modality based on the detection of Cerenkov radiation induced by beta particles when traveling though biological tissues with a velocity greater than the speed of light. We present the first human Cerenkography obtained by detecting Cerenkov radiation escaping the thyroid gland of a patient treated for hyperthyroidism. The Cerenkov light was detected using an electron multiplied charge coupled device and a conventional C-mount lens. The system set-up has been tested by using a slab of ex vivo tissue equal to a 1 cm slice of chicken breast in order to simulate optical photons attenuation. We then imaged for 2 min the head and neck region of a patient treated orally 24 h before with 550 MBq of I-131. Co-registration between photographic and Cerenkov images showed a good localization of the Cerenkov light within the thyroid region. In conclusion, we showed that it is possible to obtain a planar image of Cerenkov photons escaping from a human tissue. Cerenkography is a potential novel medical tool to image superficial organs of patients treated with beta minus radiopharmaceuticals and can be extended to the imaging of beta plus emitters.

OH PLIF measurement in a spark ignition engine with a tumble flow

NASA Astrophysics Data System (ADS)

Kumar, Siddhartha; Moronuki, Tatsuya; Shimura, Masayasu; Minamoto, Yuki; Yokomori, Takeshi; Tanahashi, Mamoru; Strategic Innovation Program (SIP) Team

2017-11-01

Under lean conditions, high compression ratio and strong tumble flow; cycle-to-cycle variations of combustion in spark ignition (SI) engines is prominent, therefore, relation between flame propagation characteristics and increase of pressure needs to be clarified. The present study is aimed at exploring the spatial and temporal development of the flame kernel using OH planar laser-induced fluorescence (OH PLIF) in an optical SI engine. Equivalence ratio is changed at a fixed indicated mean effective pressure of 400 kPa. From the measurements taken at different crank angle degrees (CAD) after ignition, characteristics of flame behavior were investigated considering temporal evolution of in-cylinder pressure, and factors causing cycle-to-cycle variations are discussed. In addition, the effects of tumble flow intensity on flame propagation behavior were also investigated. This work is supported by the Cross-ministerial Strategic Innovation Program (SIP), `Innovative Combustion Technology'.

Refractive index and solubility control of para-cymene solutions for index-matched fluid-structure interaction studies

NASA Astrophysics Data System (ADS)

Fort, Charles; Fu, Christopher D.; Weichselbaum, Noah A.; Bardet, Philippe M.

2015-12-01

To deploy optical diagnostics such as particle image velocimetry or planar laser-induced fluorescence (PLIF) in complex geometries, it is beneficial to use index-matched facilities. A binary mixture of para-cymene and cinnamaldehyde provides a viable option for matching the refractive index of acrylic, a common material for scaled models and test sections. This fluid is particularly appropriate for large-scale facilities and when a low-density and low-viscosity fluid is sought, such as in fluid-structure interaction studies. This binary solution has relatively low kinematic viscosity and density; its use enables the experimentalist to select operating temperature and to increase fluorescence signal in PLIF experiments. Measurements of spectral and temperature dependence of refractive index, density, and kinematic viscosity are reported. The effect of the binary mixture on solubility control of Rhodamine 6G is also characterized.

On-chip collection of particles and cells by AC electroosmotic pumping and dielectrophoresis using asymmetric microelectrodes.

PubMed

Melvin, Elizabeth M; Moore, Brandon R; Gilchrist, Kristin H; Grego, Sonia; Velev, Orlin D

2011-09-01

The recent development of microfluidic "lab on a chip" devices requiring sample sizes <100 μL has given rise to the need to concentrate dilute samples and trap analytes, especially for surface-based detection techniques. We demonstrate a particle collection device capable of concentrating micron-sized particles in a predetermined area by combining AC electroosmosis (ACEO) and dielectrophoresis (DEP). The planar asymmetric electrode pattern uses ACEO pumping to induce equal, quadrilateral flow directed towards a stagnant region in the center of the device. A number of system parameters affecting particle collection efficiency were investigated including electrode and gap width, chamber height, applied potential and frequency, and number of repeating electrode pairs and electrode geometry. The robustness of the on-chip collection design was evaluated against varying electrolyte concentrations, particle types, and particle sizes. These devices are amenable to integration with a variety of detection techniques such as optical evanescent waveguide sensing.

Experimental and computational fluid dynamics studies of mixing of complex oral health products

NASA Astrophysics Data System (ADS)

Cortada-Garcia, Marti; Migliozzi, Simona; Weheliye, Weheliye Hashi; Dore, Valentina; Mazzei, Luca; Angeli, Panagiota; ThAMes Multiphase Team

2017-11-01

Highly viscous non-Newtonian fluids are largely used in the manufacturing of specialized oral care products. Mixing often takes place in mechanically stirred vessels where the flow fields and mixing times depend on the geometric configuration and the fluid physical properties. In this research, we study the mixing performance of complex non-Newtonian fluids using Computational Fluid Dynamics models and validate them against experimental laser-based optical techniques. To this aim, we developed a scaled-down version of an industrial mixer. As test fluids, we used mixtures of glycerol and a Carbomer gel. The viscosities of the mixtures against shear rate at different temperatures and phase ratios were measured and found to be well described by the Carreau model. The numerical results were compared against experimental measurements of velocity fields from Particle Image Velocimetry (PIV) and concentration profiles from Planar Laser Induced Fluorescence (PLIF).

Simultaneous measurement of the surface temperature and the release of atomic sodium from a burning black liquor droplet

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

Saw, Woei L.; Nathan, Graham J.; School of Mechanical Engineering, The University of Adelaide

2010-04-15

Simultaneous measurement of the concentration of released atomic sodium, swelling, surface and internal temperature of a burning black liquor droplet under a fuel lean and rich condition has been demonstrated. Two-dimensional two-colour optical pyrometry was employed to determine the distribution of surface temperature and swelling of a burning black liquor droplet while planar laser-induced fluorescence (PLIF) was used to assess the temporal release of atomic sodium. The key findings of these studies are: (i) the concentration of atomic sodium released during the drying and devolatilisation stages was found to be correlated with the external surface area; and (ii) the insignificantmore » presence of atomic sodium during the char consumption stage shows that sodium release is suppressed by the lower temperature and by the high CO{sub 2} content in and around the particle. (author)« less

Distinguishing shocked from tectonically deformed quartz by the use of the SEM and chemical etching

USGS Publications Warehouse

Gratz, A.J.; Fisler, D.K.; Bohor, B.F.

1996-01-01

Multiple sets of crystallographically-oriented planar deformation features (PDFs) are generated by high-strain-rate shock waves at pressures of > 12 GPa in naturally shocked quartz samples. On surfaces, PDFs appear as narrow (50-500 nm) lamellae filled with amorphosed quartz (diaplectic glass) which can be etched with hydrofluoric acid or with hydrothermal alkaline solutions. In contrast, slow-strain-rate tectonic deformation pressure produces wider, semi-linear and widely spaced arrays of dislocation loops that are not glass filled. Etching samples with HF before examination in a scanning electron microscope (SEM) allows for unambiguous visual distinction between glass-filled PDFs and glass-free tectonic deformation arrays in quartz. This etching also reveals the internal 'pillaring' often characteristic of shock-induced PDFs. This technique is useful for easily distinguishing between shock and tectonic deformation in quartz, but does not replace optical techniques for characterizing the shock features.

Tilt Grain Boundary Topology Induced by Substrate Topography.

PubMed

Yu, Henry; Gupta, Nitant; Hu, Zhili; Wang, Kai; Srijanto, Bernadeta R; Xiao, Kai; Geohegan, David B; Yakobson, Boris I

2017-09-26

Synthesis of two-dimensional (2D) crystals is a topic of great current interest, since their chemical makeup, electronic, mechanical, catalytic, and optical properties are so diverse. A universal challenge, however, is the generally random formation of defects caused by various growth factors on flat surfaces. Here we show through theoretical analysis and experimental demonstration that nonplanar, curved-topography substrates permit the intentional and controllable creation of topological defects within 2D materials. We augment a common phase-field method by adding a geometric phase to track the crystal misorientation on a curved surface and to detect the formation of grain boundaries, especially when a growing monocrystal "catches its own tail" on a nontrivial topographical feature. It is specifically illustrated by simulated growth of a trigonal symmetry crystal on a conical-planar substrate, to match the experimental synthesis of WS 2 on silicon template, with satisfactory and in some cases remarkable agreement of theory predictions and experimental evidence.

Photodegradation of Selected PCBs in the Presence of Nano-TiO2 as Catalyst and H2O2 as an Oxidant

PubMed Central

Dasary, Samuel S. R.; Saloni, Julia; Fletcher, Amanda; Anjaneyulu, Yerramilli; Yu, Hongtao

2010-01-01

Photodegradation of five strategically selected PCBs was carried out in acetonitrile/water 80:20. Quantum chemical calculations reveal that PCBs without any chlorine on ortho-positions are closer to be planar, while PCBs with at least one chlorine atoms at the ortho-positions causes the two benzene rings to be nearly perpendicular. Light-induced degradation of planar PCBs is much slower than the perpendicular ones. The use of nano-TiO2 speeds up the degradation of the planar PCBs, but slows down the degradation of the non-planar ones. The use of H2O2 speeds up the degradation of planar PCBs greatly (by >20 times), but has little effect on non-planar ones except 2,3,5,6-TCB. The relative photodegradation rate is: 2,2′,4,4′-TCB > 2,3,5,6-TCB > 2,6-DCB ≈ 3,3′,4,4′-TCB > 3,4′,5-TCB. The use of H2O2 in combination with sunlight irradiation could be an efficient and “green” technology for PCB remediation. PMID:21139872

InP-based Geiger-mode avalanche photodiode arrays for three-dimensional imaging at 1.06 μm

NASA Astrophysics Data System (ADS)

Itzler, Mark A.; Entwistle, Mark; Owens, Mark; Jiang, Xudong; Patel, Ketan; Slomkowski, Krystyna; Koch, Tim; Rangwala, Sabbir; Zalud, Peter F.; Yu, Young; Tower, John; Ferraro, Joseph

2009-05-01

We report on the development of 32 x 32 focal plane arrays (FPAs) based on InGaAsP/InP Geiger-mode avalanche photodiodes (GmAPDs) designed for use in three-dimensional (3-D) laser radar imaging systems at 1064 nm. To our knowledge, this is the first realization of FPAs for 3-D imaging that employ a planar-passivated buried-junction InP-based GmAPD device platform. This development also included the design and fabrication of custom readout integrate circuits (ROICs) to perform avalanche detection and time-of-flight measurements on a per-pixel basis. We demonstrate photodiode arrays (PDAs) with a very narrow breakdown voltage distribution width of 0.34 V, corresponding to a breakdown voltage total variation of less than +/- 0.2%. At an excess bias voltage of 3.3 V, which provides 40% pixel-level single photon detection efficiency, we achieve average dark count rates of 2 kHz at an operating temperature of 248 K. We present the characterization of optical crosstalk induced by hot carrier luminescence during avalanche events, where we show that the worst-case crosstalk probability per pixel, which occurs for nearest neighbors, has a value of less than 1.6% and exhibits anisotropy due to isolation trench etch geometry. To demonstrate the FPA response to optical density variations, we show a simple image of a broadened optical beam.

Electro-plasmonic 2 × 2 channel-routing switch arranged on a thin-Si-doped metal/insulator/semiconductor/metal structure.

PubMed

Moazzam, Mostafa Keshavarz; Kaatuzian, Hassan

2016-01-20

Plasmonics as a new field of chip-scale technology is the interesting substrate of this study to propose and numerically investigate a metal/insulator/semiconductor/metal (MISM)-structure 2×2 plasmonic routing switch. As a planar subwavelength arrangement, the presented design has two npn-doped side-coupled dual waveguides whose duty is to route the propagating surface plasmon polaritons through the device. Relying on the MISM structure, which has a MOS-like thin-film arrangement of typically 45 nm doped silicon covered by a layer of 8 nm thick HfO(2) gate insulator, the routing configuration is electrically addressed based on the carrier-induced plasma dispersion effects as an external electro-plasmonic switching control. Finite-element-method-conducted electromagnetic simulations are employed to evaluate the switch optical response at telecom wavelength of λ=1550  nm, due to which the balanced operation measure of extinction ratios larger than 10 dB and insertion losses of around -1.8  dB are obtained for both channels of CROSS and STRAIGHT. Compared with other photonic and plasmonic switching counterparts, this configuration, besides its potential for CMOS compatibility, can be utilized as a high-speed compact building block to sustain higher-speed, more miniaturized, and less consuming electro-optic routing/switching protocols toward complicated optical integrated circuits and systems.

Laser-Induced Incandescence Calibration via Gravimetric Sampling

NASA Technical Reports Server (NTRS)

VanderWal, R. L.; Zhou, Z.; Choi, M. Y.

1995-01-01

Various beam imaging and/or sheet forming optics delivered light at 1064 nm from a pulsed Nd:YAG laser for use either as a beam of 3 mm radius or as a laser sheet. Imaging measurements were performed with a grated intensified array camera equipped with an ultraviolet f4.5 lens and a 40 mm extension tube. Point measurements were performed using an ultraviolet 250 mm focal length lens to collect and focus the laser induced incandescence (LII) signal into a 1 meter long quartz optical fiber which directed the LII signal to a 1/4 meter monochromator. An aperture preceding the lens restricted the signal collection region to 1 cm along the laser beam at the center of the gravimetric chimney. Signals from the PMT were processed by a boxcar integrator whereas the images were captured digitally using a frame-grabber with 16 MByte of on-board memory. Both 'point' and planar measurements were made with detector gates of 250 ns to minimize possible morphology bias in collection of the LII signal. Additionally, the imaging measurements were performed with broadband spectral collection of the LII signal to maximize the signal and again minimize any potential effects of morphology dependent heating and/or cooling rates. Digital delay generators controlled the firing of he laser, detector gates and data acquisition. Neutral density filters were used for both sets of measurements to maintain signal levels within linear dynamic ranges of the detectors, the range being determined prior to experiments.

Spectral tailoring of nanoscale EUV and soft x-ray multilayer optics

NASA Astrophysics Data System (ADS)

Huang, Qiushi; Medvedev, Viacheslav; van de Kruijs, Robbert; Yakshin, Andrey; Louis, Eric; Bijkerk, Fred

2017-03-01

Extreme ultraviolet and soft X-ray (XUV) multilayer optics have experienced significant development over the past few years, particularly on controlling the spectral characteristics of light for advanced applications like EUV photolithography, space observation, and accelerator- or lab-based XUV experiments. Both planar and three dimensional multilayer structures have been developed to tailor the spectral response in a wide wavelength range. For the planar multilayer optics, different layered schemes are explored. Stacks of periodic multilayers and capping layers are demonstrated to achieve multi-channel reflection or suppression of the reflective properties. Aperiodic multilayer structures enable broadband reflection both in angles and wavelengths, with the possibility of polarization control. The broad wavelength band multilayer is also used to shape attosecond pulses for the study of ultrafast phenomena. Narrowband multilayer monochromators are delivered to bridge the resolution gap between crystals and regular multilayers. High spectral purity multilayers with innovated anti-reflection structures are shown to select spectrally clean XUV radiation from broadband X-ray sources, especially the plasma sources for EUV lithography. Significant progress is also made in the three dimensional multilayer optics, i.e., combining micro- and nanostructures with multilayers, in order to provide new freedom to tune the spectral response. Several kinds of multilayer gratings, including multilayer coated gratings, sliced multilayer gratings, and lamellar multilayer gratings are being pursued for high resolution and high efficiency XUV spectrometers/monochromators, with their advantages and disadvantages, respectively. Multilayer diffraction optics are also developed for spectral purity enhancement. New structures like gratings, zone plates, and pyramids that obtain full suppression of the unwanted radiation and high XUV reflectance are reviewed. Based on the present achievement of the spectral tailoring multilayer optics, the remaining challenges and opportunities for future researches are discussed.

Leakage radiation interference microscopy.

PubMed

Descrovi, Emiliano; Barakat, Elsie; Angelini, Angelo; Munzert, Peter; De Leo, Natascia; Boarino, Luca; Giorgis, Fabrizio; Herzig, Hans Peter

2013-09-01

We present a proof of principle for a new imaging technique combining leakage radiation microscopy with high-resolution interference microscopy. By using oil immersion optics it is demonstrated that amplitude and phase can be retrieved from optical fields, which are evanescent in air. This technique is illustratively applied for mapping a surface mode propagating onto a planar dielectric multilayer on a thin glass substrate. The surface mode propagation constant estimated after Fourier transformation of the measured complex field is well matched with an independent measurement based on back focal plane imaging.

Enhanced optical nonlinearities in the near-infrared using III-nitride heterostructures coupled to metamaterials

DOE PAGES

Wolf, Omri; Allerman, Andrew A.; Ma, Xuedan; ...

2015-10-15

We use planar metamaterial resonators to enhance, by more than two orders of magnitude, the optical second harmonic generation, in the near infrared, obtained from intersubband transitions in III-Nitride heterostructures. The improvement arises from two factors: employing an asymmetric double quantum well design and aligning the resonators’ cross-polarized resonances with the intersubband transition energies. The resulting nonlinear metamaterial operates at wavelengths where single photon detection is available, and represents a new class of sources for quantum photonics related phenomena.

Optical property modification of PMMA by ion-beam implantation

NASA Astrophysics Data System (ADS)

Hong, Wan; Woo, Hyung-Joo; Choi, Han-Woo; Kim, Young-Suk; Kim, Gi-dong

2001-01-01

Polymeric waveguides were fabricated by proton implantation on poly(methyl methacrylate) (PMMA). Depth profiles of the refractive indices of modified regions were obtained and were found to be in good agreement with the stopping power curve of protons in PMMA. It means that the waveguides are formed at the depths where the stopping power is the maximum value. Light losses for 635 nm wavelength were measured using planar waveguides to verify if the transmittance is enough for the application of the technique to optical devices.

Design and fabrication of planar structures with graded electromagnetic properties

NASA Astrophysics Data System (ADS)

Good, Brandon Lowell

Successfully integrating electromagnetic properties in planar structures offers numerous benefits to the microwave and optical communities. This work aims at formulating new analytic and optimized design methods, creating new fabrication techniques for achieving those methods, and matching appropriate implementation of methods to fabrication techniques. The analytic method consists of modifying an approach that realizes perfect antireflective properties from graded profiles. This method is shown for all-dielectric and magneto-dielectric grading profiles. The optimized design methods are applied to transformer (discrete) or taper (continuous) designs. From these methods, a subtractive and an additive manufacturing technique were established and are described. The additive method, dry powder dot deposition, enables three dimensional varying electromagnetic properties in a structural composite. Combining the methods and fabrication is shown in two applied methodologies. The first uses dry powder dot deposition to design one dimensionally graded electromagnetic profiles in a planar fiberglass composite. The second method simultaneously applies antireflective properties and adjusts directivity through a slab through the use of subwavelength structures to achieve a flat antireflective lens. The end result of this work is a complete set of methods, formulations, and fabrication techniques to achieve integrated electromagnetic properties in planar structures.

Polymer planar waveguide Bragg gratings: fabrication, characterization, and sensing applications

NASA Astrophysics Data System (ADS)

Rosenberger, M.; Hessler, S.; Pauer, H.; Girschikofsky, M.; Roth, G. L.; Adelmann, B.; Woern, H.; Schmauss, B.; Hellmann, R.

2017-02-01

In this contribution, we give a comprehensive overview of the fabrication, characterization, and application of integrated planar waveguide Bragg gratings (PPBGs) in cyclo-olefin copolymers (COC). Starting with the measurement of the refractive index depth profile of integrated UV-written structures in COC by phase shifting Mach-Zehnder- Interferometry, we analyze the light propagation using numerical simulations. Furthermore, we show the rapid fabrication of humidity insensitive polymer waveguide Bragg gratings in cyclo-olefin copolymers and discuss the influence of the UV-dosage onto the spectral characteristics and the transmission behavior of the waveguide. Based on these measurements we exemplify that our Bragg gratings exhibit a reflectivity of over 99 % and are highly suitable for sensing applications. With regard to a negligible affinity to absorb water and in conjunction with high temperature stability these polymer devices are ideal for mechanical deformation sensing. Since planar structures are not limited to tensile but can also be applied for measuring compressive strain, we manufacture different functional devices and corroborate their applicability as optical sensors. Exemplarily, we highlight a temperature referenced PPBG sensor written into a femtosecond-laser cut tensile test geometry for tensile and compressive strain sensing. Furthermore, a flexible polymer planar shape sensor is presented.

Parametric study of the mode coupling instability for a simple system with planar or rectilinear friction

NASA Astrophysics Data System (ADS)

Charroyer, L.; Chiello, O.; Sinou, J.-J.

2016-12-01

In this paper, the study of a damped mass-spring system of three degrees of freedom with friction is proposed in order to highlight the differences in mode coupling instabilities between planar and rectilinear friction assumptions. Well-known results on the effect of structural damping in the field of friction-induced vibration are extended to the specific case of a damped mechanical system with planar friction. It is emphasised that the lowering and smoothing effects are not so intuitive in this latter case. The stability analysis is performed by calculating the complex eigenvalues of the linearised system and by using the Routh-Hurwitz criterion. Parametric studies are carried out in order to evaluate the effects of various system parameters on stability. Special attention is paid to the understanding of the role of damping and the associated destabilisation paradox in mode-coupling instabilities with planar and rectilinear friction assumptions.

A strained silicon cold electron bolometer using Schottky contacts

NASA Astrophysics Data System (ADS)

Brien, T. L. R.; Ade, P. A. R.; Barry, P. S.; Dunscombe, C.; Leadley, D. R.; Morozov, D. V.; Myronov, M.; Parker, E. H. C.; Prest, M. J.; Prunnila, M.; Sudiwala, R. V.; Whall, T. E.; Mauskopf, P. D.

2014-07-01

We describe optical characterisation of a strained silicon cold electron bolometer (CEB), operating on a 350 mK stage, designed for absorption of millimetre-wave radiation. The silicon cold electron bolometer utilises Schottky contacts between a superconductor and an n++ doped silicon island to detect changes in the temperature of the charge carriers in the silicon, due to variations in absorbed radiation. By using strained silicon as the absorber, we decrease the electron-phonon coupling in the device and increase the responsivity to incoming power. The strained silicon absorber is coupled to a planar aluminium twin-slot antenna designed to couple to 160 GHz and that serves as the superconducting contacts. From the measured optical responsivity and spectral response, we calculate a maximum optical efficiency of 50% for radiation coupled into the device by the planar antenna and an overall noise equivalent power, referred to absorbed optical power, of 1.1×10-16 W Hz-1/2 when the detector is observing a 300 K source through a 4 K throughput limiting aperture. Even though this optical system is not optimized, we measure a system noise equivalent temperature difference of 6 mK Hz-1/2. We measure the noise of the device using a cross-correlation of time stream data, measured simultaneously with two junction field-effect transistor amplifiers, with a base correlated noise level of 300 pV Hz-1/2 and find that the total noise is consistent with a combination of photon noise, current shot noise, and electron-phonon thermal noise.

Microoptical System And Fabrication Method Therefor

DOEpatents

Sweatt, William C.; Christenson, Todd R.

2005-03-15

Microoptical systems with clear aperture of about one millimeter or less are fabricated from a layer of photoresist using a lithographic process to define the optical elements. A deep X-ray source is typically used to expose the photoresist. Exposure and development of the photoresist layer can produce planar, cylindrical, and radially symmetric micro-scale optical elements, comprising lenses, mirrors, apertures, diffractive elements, and prisms, monolithically formed on a common substrate with the mutual optical alignment required to provide the desired system functionality. Optical alignment can be controlled to better than one micron accuracy. Appropriate combinations of structure and materials enable optical designs that include corrections for chromatic and other optical aberrations. The developed photoresist can be used as the basis for a molding operation to produce microoptical systems made of a range of optical materials. Finally, very complex microoptical systems can be made with as few as three lithographic exposures.

A fast low-power optical memory based on coupled micro-ring lasers

NASA Astrophysics Data System (ADS)

Hill, Martin T.; Dorren, Harmen J. S.; de Vries, Tjibbe; Leijtens, Xaveer J. M.; den Besten, Jan Hendrik; Smalbrugge, Barry; Oei, Yok-Siang; Binsma, Hans; Khoe, Giok-Djan; Smit, Meint K.

2004-11-01

The increasing speed of fibre-optic-based telecommunications has focused attention on high-speed optical processing of digital information. Complex optical processing requires a high-density, high-speed, low-power optical memory that can be integrated with planar semiconductor technology for buffering of decisions and telecommunication data. Recently, ring lasers with extremely small size and low operating power have been made, and we demonstrate here a memory element constructed by interconnecting these microscopic lasers. Our device occupies an area of 18 × 40µm2 on an InP/InGaAsP photonic integrated circuit, and switches within 20ps with 5.5fJ optical switching energy. Simulations show that the element has the potential for much smaller dimensions and switching times. Large numbers of such memory elements can be densely integrated and interconnected on a photonic integrated circuit: fast digital optical information processing systems employing large-scale integration should now be viable.

Microoptical system and fabrication method therefor

DOEpatents

Sweatt, William C.; Christenson, Todd R.

2003-07-08

Microoptical systems with clear aperture of about one millimeter or less are fabricated from a layer of photoresist using a lithographic process to define the optical elements. A deep X-ray source is typically used to expose the photoresist. Exposure and development of the photoresist layer can produce planar, cylindrical, and radially symmetric micro-scale optical elements, comprising lenses, mirrors, apertures, diffractive elements, and prisms, monolithically formed on a common substrate with the mutual optical alignment required to provide the desired system functionality. Optical alignment can be controlled to better than one micron accuracy. Appropriate combinations of structure and materials enable optical designs that include corrections for chromatic and other optical aberrations. The developed photoresist can be used as the basis for a molding operation to produce microoptical systems made of a range of optical materials. Finally, very complex microoptical systems can be made with as few as three lithographic exposures.

Integrated all-optical logic discriminators based on plasmonic bandgap engineering

PubMed Central

Lu, Cuicui; Hu, Xiaoyong; Yang, Hong; Gong, Qihuang

2013-01-01

Optical computing uses photons as information carriers, opening up the possibility for ultrahigh-speed and ultrawide-band information processing. Integrated all-optical logic devices are indispensible core components of optical computing systems. However, up to now, little experimental progress has been made in nanoscale all-optical logic discriminators, which have the function of discriminating and encoding incident light signals according to wavelength. Here, we report a strategy to realize a nanoscale all-optical logic discriminator based on plasmonic bandgap engineering in a planar plasmonic microstructure. Light signals falling within different operating wavelength ranges are differentiated and endowed with different logic state encodings. Compared with values previously reported, the operating bandwidth is enlarged by one order of magnitude. Also the SPP light source is integrated with the logic device while retaining its ultracompact size. This opens up a way to construct on-chip all-optical information processors and artificial intelligence systems. PMID:24071647

Ambiguities of a Motion Field.

DTIC Science & Technology

1987-01-01

solutions in the case of planar surfaces has since been reported by Tsai et al. 11982], Waxman & Ullman [19851, Longuet-Higgins [1984], Maybank [1984], and... Maybank , SiJ. (1984) "The Angular Velocity Associated with the Optical Flow Field due to a Single Moving Rigid Plane,’ Proceedings of the Stzth European

Structure and Optical Bandgap Relationship of π-Conjugated Systems

PubMed Central

Botelho, André Leitão; Shin, Yongwoo; Liu, Jiakai; Lin, Xi

2014-01-01

In bulk heterojunction photovoltaic systems both the open-circuit voltage as well as the short-circuit current, and hence the power conversion efficiency, are dependent on the optical bandgap of the electron-donor material. While first-principles methods are computationally intensive, simpler model Hamiltonian approaches typically suffer from one or more flaws: inability to optimize the geometries for their own input; absence of general, transferable parameters; and poor performance for non-planar systems. We introduce a set of new and revised parameters for the adapted Su-Schrieffer-Heeger (aSSH) Hamiltonian, which is capable of optimizing geometries, along with rules for applying them to any -conjugated system containing C, N, O, or S, including non-planar systems. The predicted optical bandgaps show excellent agreement to UV-vis spectroscopy data points from literature, with a coefficient of determination , a mean error of −0.05 eV, and a mean absolute deviation of 0.16 eV. We use the model to gain insights from PEDOT, fused thiophene polymers, poly-isothianaphthene, copolymers, and pentacene as sources of design rules in the search for low bandgap materials. Using the model as an in-silico design tool, a copolymer of benzodithiophenes along with a small-molecule derivative of pentacene are proposed as optimal donor materials for organic photovoltaics. PMID:24497944

On the Accuracy Potential in Underwater/Multimedia Photogrammetry.

PubMed

Maas, Hans-Gerd

2015-07-24

Underwater applications of photogrammetric measurement techniques usually need to deal with multimedia photogrammetry aspects, which are characterized by the necessity of handling optical rays that are refracted at interfaces between optical media with different refractive indices according to Snell's Law. This so-called multimedia geometry has to be incorporated into geometric models in order to achieve correct measurement results. The paper shows a flexible yet strict geometric model for the handling of refraction effects on the optical path, which can be implemented as a module into photogrammetric standard tools such as spatial resection, spatial intersection, bundle adjustment or epipolar line computation. The module is especially well suited for applications, where an object in water is observed by cameras in air through one or more planar glass interfaces, as it allows for some simplifications here. In the second part of the paper, several aspects, which are relevant for an assessment of the accuracy potential in underwater/multimedia photogrammetry, are discussed. These aspects include network geometry and interface planarity issues as well as effects caused by refractive index variations and dispersion and diffusion under water. All these factors contribute to a rather significant degradation of the geometric accuracy potential in underwater/multimedia photogrammetry. In practical experiments, a degradation of the quality of results by a factor two could be determined under relatively favorable conditions.

Mineral shock signatures in rocks from Dhala (Mohar) impact structure, Shivpuri district, Madhya Pradesh, India

NASA Astrophysics Data System (ADS)

Roy, Madhuparna; Pandey, Pradeep; Kumar, Shailendra; Parihar, P. S.

2017-12-01

A concrete study combining optical microscopy, Raman spectroscopy and X-ray diffractometry, was carried out on subsurface samples of basement granite and melt breccia from Mohar (Dhala) impact structure, Shivpuri district, Madhya Pradesh, India. Optical microscopy reveals aberrations in the optical properties of quartz and feldspar in the form of planar deformation feature-like structures, lowered birefringence and mosaics in quartz, toasting, planar fractures and ladder texture in alkali feldspar and near-isotropism in bytownite. It also brings to light incidence of parisite, a radioactive rare mineral in shocked granite. Raman spectral pattern, peak positions, peak widths and multiplicity of peak groups of all minerals, suggest subtle structural/crystallographic deviations. XRD data further reveals minute deviations of unit cell parameters of quartz, alkali feldspar and plagioclase, with respect to standard α-quartz, high- and low albite and microcline. Reduced cell volumes in these minerals indicate compression due to pressure. The c0/a0 values indicate an inter-tetrahedral angle roughly between 120o and 144o, further pointing to a possible pressure maxima of around 12 GPa. The observed unit cell aberration of minerals may indicate an intermediate stage between crystalline and amorphous stages, thereby, signifying possible overprinting of decompression signatures over shock compression effects, from a shock recovery process.

Optical characterization of the new nanocomposite SBMA/Eu(TTA)3(Ph3PO)2

NASA Astrophysics Data System (ADS)

Bordian, Olga; Verlan, Victor; Culeac, Ion; Iovu, Mihail; Zubareva, Vera; Nistor, Iurie

2015-02-01

We describe a new nanocomposite material based on the copolymer of styrene with butyl methacrylate (1:1) (SBMA), and coordinating compound of Europium(III) Eu(TTA)3(Ph3PO)2. The SBMA/Eu(TTA)3(Ph3PO)2 nanocomposite was prepared by a simple technology and can be obtained in the form of optical fibers, thin films and planar waveguides on various substrates with large area. Experimental results on optical transmission and photoluminescence spectroscopy are presented. The nanocomposite exhibits a strong photoluminescence emission in the range 560-750 nm, with the main photoluminescence band at 613 nm.

Near field optical probe for critical dimension measurements

DOEpatents

Stallard, Brian R.; Kaushik, Sumanth

1999-01-01

A resonant planar optical waveguide probe for measuring critical dimensions on an object in the range of 100 nm and below. The optical waveguide includes a central resonant cavity flanked by Bragg reflector layers with input and output means at either end. Light is supplied by a narrow bandwidth laser source. Light resonating in the cavity creates an evanescent electrical field. The object with the structures to be measured is translated past the resonant cavity. The refractive index contrasts presented by the structures perturb the field and cause variations in the intensity of the light in the cavity. The topography of the structures is determined from these variations.

Optical position measurement for a Large Gap Magnetic Suspension System

NASA Technical Reports Server (NTRS)

Welch, Sharon S.; Shelton, Kevin J.; Clemmons, James I.

1991-01-01

This paper describes the design of an optical position measurement system which is being built as part of the NASA Langley Large Gap Magnetic Suspension System (LGMSS). The LGMSS is a five degree-of-freedom, large-gap magnetic suspension system which is being built for Langley Research Center as part of the Advanced Controls Test Facility (ACTF). The LGMSS consists of a planar array of electromagnets which levitate and position a cylindrically shaped model containing a permanent magnet core. The optical position measurement system provides information on the location and orientation of the model to the LGMSS control system to stabilize levitation of the model.

Transverse-structure electrostatic charged particle beam lens

DOEpatents

Moran, M.J.

1998-10-13

Electrostatic particle-beam lenses using a concentric co-planar array of independently biased rings can be advantageous for some applications. Traditional electrostatic lenses often consist of axial series of biased rings, apertures, or tubes. The science of lens design has devoted much attention to finding axial arrangements that compensate for the substantial optical aberrations of the individual elements. Thus, as with multi-element lenses for light, a multi-element charged-particle lens can have optical behavior that is far superior to that of the individual elements. Transverse multiple-concentric-ring lenses achieve high performance, while also having advantages in terms of compactness and optical versatility. 7 figs.

Transverse-structure electrostatic charged particle beam lens

DOEpatents

Moran, Michael J.

1998-01-01

Electrostatic particle-beam lenses using a concentric co-planar array of independently biased rings can be advantageous for some applications. Traditional electrostatic lenses often consist of axial series of biased rings, apertures, or tubes. The science of lens design has devoted much attention to finding axial arrangements that compensate for the substantial optical aberrations of the individual elements. Thus, as with multi-element lenses for light, a multi-element charged-particle lens can have optical behavior that is far superior to that of the individual elements. Transverse multiple-concentric-ring lenses achieve high performance, while also having advantages in terms of compactness and optical versatility.

Controlled waveguide coupling for photon emission from colloidal PbS quantum dot using tunable microcavity made of optical polymer and silicon

NASA Astrophysics Data System (ADS)

Nozaka, Takahiro; Mukai, Kohki

2016-04-01

A tunable microcavity device composed of optical polymer and Si with a colloidal quantum dot (QD) is proposed as a single-photon source for planar optical circuit. Cavity size is controlled by electrostatic micromachine behavior with the air bridge structure to tune timing of photon injection into optical waveguide from QD. Three-dimensional positioning of a QD in the cavity structure is available using a nanohole on Si processed by scanning probe microscope lithography. We fabricated the prototype microcavity with PbS-QD-mixed polymenthyl methacrylate on a SOI (semiconductor-on-insulator) substrate to show the tunability of cavity size as the shift of emission peak wavelength of QD ensemble.

Temporal waveguides for optical pulses

DOE PAGES

Plansinis, Brent W.; Donaldson, William R.; Agrawal, Govind P.

2016-05-12

Here we discuss, temporal total internal reflection (TIR), in analogy to the conventional TIR of an optical beam at a dielectric interface, is the total reflection of an optical pulse inside a dispersive medium at a temporal boundary across which the refractive index changes. A pair of such boundaries separated in time acts as the temporal analog of planar dielectric waveguides. We study the propagation of optical pulses inside such temporal waveguides, both analytically and numerically, and show that the waveguide supports a finite number of temporal modes. We also discuss how a single-mode temporal waveguide can be created inmore » practice. In contrast with the spatial case, the confinement can occur even when the central region has a lower refractive index.« less

Ta2O5/ Al2O3/ SiO2 - antireflective coating for non-planar optical surfaces by atomic layer deposition

NASA Astrophysics Data System (ADS)

Pfeiffer, K.; Schulz, U.; Tünnermann, A.; Szeghalmi, A.

2017-02-01

Antireflective coatings are essential to improve transmittance of optical elements. Most research and development of AR coatings has been reported on a wide variety of plane optical surfaces; however, antireflection is also necessary on nonplanar optical surfaces. Physical vapor deposition (PVD), a common method for optical coatings, often results in thickness gradients on strongly curved surfaces, leading to a failure of the desired optical function. In this work, optical thin films of tantalum pentoxide, aluminum oxide and silicon dioxide were prepared by atomic layer deposition (ALD), which is based on self-limiting surface reactions. The results demonstrate that ALD optical layers can be deposited on both vertical and horizontal substrate surfaces with uniform thicknesses and the same optical properties. A Ta2O5/Al2O3/ SiO2 multilayer AR coating (400-700 nm) was successfully applied to a curved aspheric glass lens with a diameter of 50 mm and a center thickness of 25 mm.

A nanostructure based on metasurfaces for optical interconnects

NASA Astrophysics Data System (ADS)

Lin, Shulang; Gu, Huarong

2017-08-01

Optical-electronic Integrated Neural Co-processor takes vital part in optical neural network, which is mainly realized by optical interconnects. Because of the accuracy requirement and long-term goal of integration, optical interconnects should be effective and pint-size. In traditional solutions of optical interconnects, holography built on crystalloid or law of Fresnel diffraction exploited on zone plate was used. However, holographic method cannot meet the efficiency requirement and zone plate is too bulk to make the optical neural unit miniaturization. Thus, this paper aims to find a way to replace holographic method or zone plate with enough diffraction efficiency and smaller size. Metasurfaces are composed of subwavelength-spaced phase shifters at an interface of medium. Metasurfaces allow for unprecedented control of light properties. They also have advanced optical technology of enabling versatile functionalities in a planar structure. In this paper, a nanostructure is presented for optical interconnects. The comparisons of light splitting ability and simulated crosstalk between nanostructure and zone plate are also made.

Method to improve optical parametric oscillator beam quality

DOEpatents

Smith, Arlee V.; Alford, William J.; Bowers, Mark S.

2003-11-11

A method to improving optical parametric oscillator (OPO) beam quality having an optical pump, which generates a pump beam at a pump frequency greater than a desired signal frequency, a nonlinear optical medium oriented so that a signal wave at the desired signal frequency and a corresponding idler wave are produced when the pump beam (wave) propagates through the nonlinear optical medium, resulting in beam walk off of the signal and idler waves, and an optical cavity which directs the signal wave to repeatedly pass through the nonlinear optical medium, said optical cavity comprising an equivalently even number of non-planar mirrors that produce image rotation on each pass through the nonlinear optical medium. Utilizing beam walk off where the signal wave and said idler wave have nonparallel Poynting vectors in the nonlinear medium and image rotation, a correlation zone of distance equal to approximately .rho.L.sub.crystal is created which, through multiple passes through the nonlinear medium, improves the beam quality of the OPO output.

Optical parametric osicllators with improved beam quality

DOEpatents

Smith, Arlee V.; Alford, William J.

2003-11-11

An optical parametric oscillator (OPO) having an optical pump, which generates a pump beam at a pump frequency greater than a desired signal frequency, a nonlinear optical medium oriented so that a signal wave at the desired signal frequency and a corresponding idler wave are produced when the pump beam (wave) propagates through the nonlinear optical medium, resulting in beam walk off of the signal and idler waves, and an optical cavity which directs the signal wave to repeatedly pass through the nonlinear optical medium, said optical cavity comprising an equivalently even number of non-planar mirrors that produce image rotation on each pass through the nonlinear optical medium. Utilizing beam walk off where the signal wave and said idler wave have nonparallel Poynting vectors in the nonlinear medium and image rotation, a correlation zone of distance equal to approximately .rho.L.sub.crystal is created which, through multiple passes through the nonlinear medium, improves the beam quality of the OPO output.

High frequency resolution terahertz time-domain spectroscopy

NASA Astrophysics Data System (ADS)

Sangala, Bagvanth Reddy

2013-12-01

A new method for the high frequency resolution terahertz time-domain spectroscopy is developed based on the characteristic matrix method. This method is useful for studying planar samples or stack of planar samples. The terahertz radiation was generated by optical rectification in a ZnTe crystal and detected by another ZnTe crystal via electro-optic sampling method. In this new characteristic matrix based method, the spectra of the sample and reference waveforms will be modeled by using characteristic matrices. We applied this new method to measure the optical constants of air. The terahertz transmission through the layered systems air-Teflon-air-Quartz-air and Nitrogen gas-Teflon-Nitrogen gas-Quartz-Nitrogen gas was modeled by the characteristic matrix method. A transmission coefficient is derived from these models which was optimized to fit the experimental transmission coefficient to extract the optical constants of air. The optimization of an error function involving the experimental complex transmission coefficient and the theoretical transmission coefficient was performed using patternsearch algorithm of MATLAB. Since this method takes account of the echo waveforms due to reflections in the layered samples, this method allows analysis of longer time-domain waveforms giving rise to very high frequency resolution in the frequency-domain. We have presented the high frequency resolution terahertz time-domain spectroscopy of air and compared the results with the literature values. We have also fitted the complex susceptibility of air to the Lorentzian and Gaussian functions to extract the linewidths.

Design of a nanopatterned long focal-length planar focusing collector for concentrated solar power

NASA Astrophysics Data System (ADS)

Ding, Qing; Choubal, Aakash; Toussaint, Kimani C.

2017-02-01

Concentrated solar power (CSP) facilities heavily utilize parabolic troughs to collect and concentrate sunlight onto receivers that deliver solar thermal energy to heat engines for generating electricity. However, parabolic troughs are bulky and heavy and result in a large capital investment for CSP plants, thereby making it difficult for CSP technology to be competitive with photovoltaics. We present the design of a planar focusing collector (PFC) with focal length beyond the micron scale. The PFC design is based on the use of a nanostructured silver surface for linearly polarized singlewavelength light. The designed PFC consists of metallic nanogrooves on a dielectric substrate. The geometric properties, namely the width and depth, of a single-unit nanogroove allows for full control of the optical phase at desired spatial coordinates along the nanogroove short-axis for a single wavelength. Moreover, we show numerically that such phase control can be used to construct a phase front that mimics that of a cylindrical lens. In addition, we determine the concentration ratio by comparing the width of our PFC design to the cross-sectional width of its focal spot. We also determine the conversion efficiency at long focal lengths by evaluating the ratio of the collected optical power to the incoming optical power. Finally, we examine the focusing behavior across multiple wavelengths and angles of incidence. Our work shows how nano-optics and plasmonics could contribute to this important area of CSP technology.

Gamma-insensitive optical sensor

DOEpatents

Kruger, Hans W.

1994-01-01

An ultra-violet/visible/infra-red gamma-insensitive gas avalanche focal plane array comprising a planar photocathode and a planar anode pad array separated by a gas-filled gap and across which is applied an electric potential. Electrons ejected from the photocathode are accelerated sufficiently between collisions with the gas molecules to ionize them, forming an electron avalanche. The gap acts like a proportional counter. The array of anode pad are mounted on the front of an anode plate and are connected to matching contact pads on the back of the anode via feed through wires. Connection of the anode to signal processing electronics is made from the contact pads using standard indium bump techniques, for example.

Design optimization of integrated BiDi triplexer optical filter based on planar lightwave circuit.

PubMed

Xu, Chenglin; Hong, Xiaobin; Huang, Wei-Ping

2006-05-29

Design optimization of a novel integrated bi-directional (BiDi) triplexer filter based on planar lightwave circuit (PLC) for fiber-to-the premise (FTTP) applications is described. A multi-mode interference (MMI) device is used to filter the up-stream 1310nm signal from the down-stream 1490nm and 1555nm signals. An array waveguide grating (AWG) device performs the dense WDM function by further separating the two down-stream signals. The MMI and AWG are built on the same substrate with monolithic integration. The design is validated by simulation, which shows excellent performance in terms of filter spectral characteristics (e.g., bandwidth, cross-talk, etc.) as well as insertion loss.

Design optimization of integrated BiDi triplexer optical filter based on planar lightwave circuit

NASA Astrophysics Data System (ADS)

Xu, Chenglin; Hong, Xiaobin; Huang, Wei-Ping

2006-05-01

Design optimization of a novel integrated bi-directional (BiDi) triplexer filter based on planar lightwave circuit (PLC) for fiber-to-the premise (FTTP) applications is described. A multi-mode interference (MMI) device is used to filter the up-stream 1310nm signal from the down-stream 1490nm and 1555nm signals. An array waveguide grating (AWG) device performs the dense WDM function by further separating the two down-stream signals. The MMI and AWG are built on the same substrate with monolithic integration. The design is validated by simulation, which shows excellent performance in terms of filter spectral characteristics (e.g., bandwidth, cross-talk, etc.) as well as insertion loss.

Surge Flow in a Centrifugal Compressor Measured by Digital Particle Image Velocimetry

NASA Technical Reports Server (NTRS)

Wernet, Mark P.

2000-01-01

A planar optical velocity measurement technique known as Particle Image Velocimetry (PIV) is being used to study transient events in compressors. In PIV, a pulsed laser light sheet is used to record the positions of particles entrained in a fluid at two instances in time across a planar region of the flow. Determining the recorded particle displacement between exposures yields an instantaneous velocity vector map across the illuminated plane. Detailed flow mappings obtained using PIV in high-speed rotating turbomachinery components are used to improve the accuracy of computational fluid dynamics (CFD) simulations, which in turn, are used to guide advances in state-of-the-art aircraft engine hardware designs.

Parabolic crossed planar polymeric x-ray lenses

NASA Astrophysics Data System (ADS)

Nazmov, V.; Reznikova, E.; Mohr, J.; Saile, V.; Vincze, L.; Vekemans, B.; Bohic, S.; Somogyi, A.

2011-01-01

The principles of design and manufacturing of the polymer planar x-ray lenses focusing in one and two directions, as well as the peculiarities of optical behaviors and the results of the lens test are reported in this paper. The methods of electron and deep x-ray lithography used in lens manufacturing allow the manufacture of ten or more x-ray lenses on one substrate; the lenses show focal lengths down to several centimeters for photon energies between 5 and 40 keV. The measured focus size was 105 nm for a linear lens with an intensity gain of about 407, and 300 × 770 nm for a crossed lens with an intensity gain of 6470.

A reusable evanescent wave immunosensor for highly sensitive detection of bisphenol A in water samples

NASA Astrophysics Data System (ADS)

Xiao-Hong, Zhou; Lan-Hua, Liu; Wei-Qi, Xu; Bao-Dong, Song; Jian-Wu, Sheng; Miao, He; Han-Chang, Shi

2014-04-01

This paper proposed a compact and portable planar waveguide evanescent wave immunosensor (EWI) for highly sensitive detection of BPA. The incident light is coupled into the planar waveguide chip via a beveled angle through undergoing total internal reflection, where the evanescent wave field forms and excites the binding fluorophore-tagged antibodies on the chip surface. Typical calibration curves obtained for BPA has detection limits of 0.03 μg/L. Linear response for BPA ranged from 0.124 μg/L-9.60 μg/L with 50% inhibition concentration for BPA of 1.09 +/- 0.25 μg/L. The regeneration of the planar optical waveguide chip allows the performance of more than 300 assay cycles within an analysis time of about 20 min for each assay cycle. By application of effective pretreatment procedure, the recoveries of BPA in real water samples gave values from 88.3% +/- 8.5% to 103.7% +/- 3.5%, confirming its application potential in the measurement of BPA in reality.

Surface Plasmon Polariton-Assisted Long-Range Exciton Transport in Monolayer Semiconductor Lateral Heterostructure

NASA Astrophysics Data System (ADS)

Shi, Jinwei; Lin, Meng-Hsien; Chen, Yi-Tong; Estakhri, Nasim Mohammadi; Tseng, Guo-Wei; Wang, Yanrong; Chen, Hung-Ying; Chen, Chun-An; Shih, Chih-Kang; Alã¹, Andrea; Li, Xiaoqin; Lee, Yi-Hsien; Gwo, Shangjr

Recently, two-dimensional (2D) semiconductor heterostructures, i.e., atomically thin lateral heterostructures (LHSs) based on transition metal dichalcogenides (TMDs) have been demonstrated. In an optically excited LHS, exciton transport is typically limited to a rather short spatial range ( 1 micron). Furthermore, additional losses may occur at the lateral interfacial regions. Here, to overcome these challenges, we experimentally implement a planar metal-oxide-semiconductor (MOS) structure by placing a monolayer of WS2/MoS2 LHS on top of an Al2O3 capped Ag single-crystalline plate. We found that the exciton transport range can be extended to tens of microns. The process of long-range exciton transport in the MOS structure is confirmed to be mediated by an exciton-surface plasmon polariton-exciton conversion mechanism, which allows a cascaded energy transfer process. Thus, the planar MOS structure provides a platform seamlessly combining 2D light-emitting materials with plasmonic planar waveguides, offering great potential for developing integrated photonic/plasmonic functionalities.

Shear-induced desorption of isolated polymer molecules from a planar wall

NASA Astrophysics Data System (ADS)

Dutta, Sarit; Dorfman, Kevin; Kumar, Satish

2014-03-01

Shear-induced desorption of isolated polymer molecules is studied using Brownian dynamics simulations. The polymer molecules are modeled as freely jointed bead-spring chains interacting with a planar wall via a short-range potential. The simulations include both intrachain and chain-wall hydrodynamic interactions. Shear flow is found to cause chain flattening, resulting at low shear rates in an increased fraction of chain segments bound to the wall. However, above a critical shear rate the chains desorb completely. The desorption process is nucleated by random protrusions in the shear gradient direction which evolve under the combined effect of drag, hydrodynamic interaction, and vorticity-induced rotation, and subsequently lead to recapture. Above the critical shear rate, these protrusions grow in length until the entire chain is peeled off the wall. For free-draining chains, the protrusions are not sustained and no desorption is observed even at shear rates much higher than the critical value. These simulations can help in interpreting experiments on shear-induced desorption of polymer films and brushes.

Measuring vertical oxygen profiles in the hyporheic zone using planar optodes

NASA Astrophysics Data System (ADS)

Vieweg, M.; Fleckenstein, J. H.; Schmidt, C.

2012-04-01

On of the key parameters, controlling biogeochemical reactions in the hyporheic zone (HZ) is the distribution of oxygen. A reliable measurement of the vertical oxygen distribution is an important tool to understand the dynamic fluctuations of the aerobic zone within the HZ. With repeated measurements of continuous profiles, mixing of surface water and groundwater as well as the consumption of oxygen can be evaluated. We present a novel approach for the in situ measurements of vertical oxygen distribution in the riverbed using a planar optode. The luminescence based optode measurement enables a non invasive measurement without consumption of oxygen, no creation of preferential flow paths and only minimal disturbance of the flow field. Possible atmospheric contamination by pumping pore water into a vessel can be avoided and the readings are independent of flow velocity. A self manufactured planar optode is wrapped around an acrylic tube and installed in the riverbed. The measurement is performed by vertically moving a profiler-piston inside the acrylic tube. The piston holds a robust polymer optical fibre which emits a modulated light signal through the acrylic glass to the optode-foil and transmits the induced luminescence signal back to a commercially available trace oxygen meter. Temperature compensation is accomplished using a depth-oriented temperature probe nearby and processing the raw data within a Matlab script. Robust and unbiased oxygen profiles are obtained by averaging multiple consecutive measurements. To ensure a constant velocity of the profiler for replicating the exact measuring depths, an electric motor device is used. First results at our test site show a variable oxygen profile down to 40 cm depth which is strongly influenced by stream level and upwelling groundwater conditions. The measured oxygen profiles will serve as input parameter for a 3D solute transport and chemical reaction subsurface model of the HZ.

Laser printed glass planar lightwave circuits with integrated fiber alignment structures

NASA Astrophysics Data System (ADS)

Desmet, A.; Radosavljevic, A.; Missinne, J.; Van Thourhout, D.; Van Steenberge, G.

2018-02-01

Femtosecond laser inscription allows straightforward manufacturing of glass planar lightwave circuits such as waveguides, interferometers, directional couplers, resonators and more complex structures. Fiber alignment structures are needed to facilitate communication with the glass planar lightwave circuit. In this study, a technique is described to create optical waveguides and alignment structures in the same laser exposure step. Using an industrial ytterbium-doped 1030 nm fiber laser pulses of 400 fs were focused into glass with a 0.4 NA objective causing permanent alteration of the material. Depending on laser parameters this modification allows direct writing of waveguides or the creation of channels after exposing the irradiated volumes to an etchant such as KOH. Writing of channels and waveguides with different laser powers, frequencies, polarisations, stage translation speeds and scan densities were investigated in fused silica and borosilicate glass. Waveguides with controlled dimensions were created, as well as etched U-grooves with a diameter of 126 μm and a sidewall roughness Ra of 255 nm. Cut back measurements were performed giving a waveguide propagation loss of 1.1 dB/cm in borosilicate glass. A coupling loss of 0.7 dB was measured for a transition between the waveguide and standard single mode fiber at 1550 nm, using index matching liquid. The described technique eliminates active alignment requirements and is useful for many applications such as microfluidic sensing, PLCs, fan-out connectors for multicore fibers and quantum optical networks.

Data Retrieval Algorithms for Validating the Optical Transient Detector and the Lightning Imaging Sensor

NASA Technical Reports Server (NTRS)

Koshak, W. J.; Blakeslee, R. J.; Bailey, J. C.

2000-01-01

A linear algebraic solution is provided for the problem of retrieving the location and time of occurrence of lightning ground strikes from an Advanced Lightning Direction Finder (ALDF) network. The ALDF network measures field strength, magnetic bearing, and arrival time of lightning radio emissions. Solutions for the plane (i.e., no earth curvature) are provided that implement all of these measurements. The accuracy of the retrieval method is tested using computer-simulated datasets, and the relative influence of bearing and arrival time data an the outcome of the final solution is formally demonstrated. The algorithm is sufficiently accurate to validate NASA:s Optical Transient Detector and Lightning Imaging Sensor. A quadratic planar solution that is useful when only three arrival time measurements are available is also introduced. The algebra of the quadratic root results are examined in detail to clarify what portions of the analysis region lead to fundamental ambiguities in sc)iirce location, Complex root results are shown to be associated with the presence of measurement errors when the lightning source lies near an outer sensor baseline of the ALDF network. For arbitrary noncollinear network geometries and in the absence of measurement errors, it is shown that the two quadratic roots are equivalent (no source location ambiguity) on the outer sensor baselines. The accuracy of the quadratic planar method is tested with computer-generated datasets, and the results are generally better than those obtained from the three-station linear planar method when bearing errors are about 2 deg.

Processing and optical properties of Nd3+-doped SiO2-TiO2-Al2O3 planar waveguides

NASA Astrophysics Data System (ADS)

Xiang, Qing; Zhou, Yan; Ooi, Boon Siew; Lam, Yee Loy; Chan, Yuen Chuen; Kam, Chan Hin

2000-05-01

We report here the processing and optical characterization of Nd3+-doped SiO2-TiO2-Al2O3 planar waveguides deposited on SOS substrates by the sol-gel route combined with spin-coating and rapid thermal annealing. The recipes used for preparing the solutions by sol-gel route are in mole ratio of 93SiO2:20AlO1.5: x ErO1.5. In order to verify the residual OH content in the films, FTIR spectra were measured and the morphology of the material by the XRD analysis. Five 2-layer films annealed at a maximum temperature of 500 degrees C, 700 degrees C, 900 degrees, 1000 degrees C, 1100 degrees C respectively were fabricated on silicon. The FTIR and XRD curves show that annealing at 1050 degrees C for 15s effectively removes the OH in the materia and keeps the material amorphous. The propagation loss of the planar waveguides was measured by using the method based on scattering in measurements and the result was obtained to be 1.54dB/cm. The fluorescence spectra were measured with 514nm wavelength of Ar+ laser by directly shining the pump beam on the film instead of prism coupling. The results show that the 1 mole Nd3+ content recipe has the strongest emission efficiency among the four samples investigated.

Hybrid two-dimensional navigator correction: a new technique to suppress respiratory-induced physiological noise in multi-shot echo-planar functional MRI

PubMed Central

Barry, Robert L.; Klassen, L. Martyn; Williams, Joy M.; Menon, Ravi S.

2008-01-01

A troublesome source of physiological noise in functional magnetic resonance imaging (fMRI) is due to the spatio-temporal modulation of the magnetic field in the brain caused by normal subject respiration. fMRI data acquired using echo-planar imaging is very sensitive to these respiratory-induced frequency offsets, which cause significant geometric distortions in images. Because these effects increase with main magnetic field, they can nullify the gains in statistical power expected by the use of higher magnetic fields. As a study of existing navigator correction techniques for echo-planar fMRI has shown that further improvements can be made in the suppression of respiratory-induced physiological noise, a new hybrid two-dimensional (2D) navigator is proposed. Using a priori knowledge of the slow spatial variations of these induced frequency offsets, 2D field maps are constructed for each shot using spatial frequencies between ±0.5 cm−1 in k-space. For multi-shot fMRI experiments, we estimate that the improvement of hybrid 2D navigator correction over the best performance of one-dimensional navigator echo correction translates into a 15% increase in the volume of activation, 6% and 10% increases in the maximum and average t-statistics, respectively, for regions with high t-statistics, and 71% and 56% increases in the maximum and average t-statistics, respectively, in regions with low t-statistics due to contamination by residual physiological noise. PMID:18024159

A dynamic magneto-optical trap for atom chips

NASA Astrophysics Data System (ADS)

Rushton, Jo; Roy, Ritayan; Bateman, James; Himsworth, Matt

2016-11-01

We describe a dynamic magneto-optical trap (MOT) suitable for the use with vacuum systems in which optical access is limited to a single window. This technique facilitates the long-standing desire of producing integrated atom chips, many of which are likely to have severely restricted optical access compared with conventional vacuum chambers. This ‘switching-MOT’ relies on the synchronized pulsing of optical and magnetic fields at audio frequencies. The trap’s beam geometry is obtained using a planar mirror surface, and does not require a patterned substrate or bulky optics inside the vacuum chamber. Central to the design is a novel magnetic field geometry that requires no external quadrupole or bias coils which leads toward a very compact system. We have implemented the trap for 85Rb and shown that it is capable of capturing 2 million atoms and directly cooling below the Doppler temperature.

Catenary optics for achromatic generation of perfect optical angular momentum

PubMed Central

Pu, Mingbo; Li, Xiong; Ma, Xiaoliang; Wang, Yanqin; Zhao, Zeyu; Wang, Changtao; Hu, Chenggang; Gao, Ping; Huang, Cheng; Ren, Haoran; Li, Xiangping; Qin, Fei; Yang, Jing; Gu, Min; Hong, Minghui; Luo, Xiangang

2015-01-01

The catenary is the curve that a free-hanging chain assumes under its own weight, and thought to be a “true mathematical and mechanical form” in architecture by Robert Hooke in the 1670s, with nevertheless no significant phenomena observed in optics. We show that the optical catenary can serve as a unique building block of metasurfaces to produce continuous and linear phase shift covering [0, 2π], a mission that is extremely difficult if not impossible for state-of-the-art technology. Via catenary arrays, planar optical devices are designed and experimentally characterized to generate various kinds of beams carrying orbital angular momentum (OAM). These devices can operate in an ultra-broadband spectrum because the anisotropic modes associated with the spin-orbit interaction are almost independent of the incident light frequency. By combining the optical and topological characteristics, our approach would allow the complete control of photons within a single nanometric layer. PMID:26601283

Free-space wavelength-multiplexed optical scanner demonstration.

PubMed

Yaqoob, Zahid; Riza, Nabeel A

2002-09-10

Experimental demonstration of a no-moving-parts free-space wavelength-multiplexed optical scanner (W-MOS) is presented. With fast tunable lasers or optical filters and planar wavelength dispersive elements such as diffraction gratings, this microsecond-speed scanner enables large several-centimeter apertures for subdegree angular scans. The proposed W-MOS design incorporates a unique optical amplifier and variable optical attenuator combination that enables the calibration and modulation of the scanner response, leading to any desired scanned laser beam power shaping. The experimental setup uses a tunable laser centered at 1560 nm and a 600-grooves/mm blazed reflection grating to accomplish an angular scan of 12.92 degrees as the source is tuned over an 80-nm bandwidth. The values for calculated maximum optical beam divergance, required wavelength resolution, beam-pointing accuracy, and measured scanner insertion loss are 1.076 mrad, 0.172 nm, 0.06 mrad, and 4.88 dB, respectively.

Real-Space Mapping of the Chiral Near-Field Distributions in Spiral Antennas and Planar Metasurfaces.

PubMed

Schnell, M; Sarriugarte, P; Neuman, T; Khanikaev, A B; Shvets, G; Aizpurua, J; Hillenbrand, R

2016-01-13

Chiral antennas and metasurfaces can be designed to react differently to left- and right-handed circularly polarized light, which enables novel optical properties such as giant optical activity and negative refraction. Here, we demonstrate that the underlying chiral near-field distributions can be directly mapped with scattering-type scanning near-field optical microscopy employing circularly polarized illumination. We apply our technique to visualize, for the first time, the circular-polarization selective nanofocusing of infrared light in Archimedean spiral antennas, and explain this chiral optical effect by directional launching of traveling waves in analogy to antenna theory. Moreover, we near-field image single-layer rosette and asymmetric dipole-monopole metasurfaces and find negligible and strong chiral optical near-field contrast, respectively. Our technique paves the way for near-field characterization of optical chirality in metal nanostructures, which will be essential for the future development of chiral antennas and metasurfaces and their applications.

Broadband high-efficiency dielectric metasurfaces for the visible spectrum

PubMed Central

Devlin, Robert C.; Khorasaninejad, Mohammadreza; Chen, Wei Ting; Oh, Jaewon; Capasso, Federico

2016-01-01

Metasurfaces are planar optical elements that hold promise for overcoming the limitations of refractive and conventional diffractive optics. Original dielectric metasurfaces are limited to transparency windows at infrared wavelengths because of significant optical absorption and loss at visible wavelengths. Thus, it is critical that new materials and nanofabrication techniques be developed to extend dielectric metasurfaces across the visible spectrum and to enable applications such as high numerical aperture lenses, color holograms, and wearable optics. Here, we demonstrate high performance dielectric metasurfaces in the form of holograms for red, green, and blue wavelengths with record absolute efficiency (>78%). We use atomic layer deposition of amorphous titanium dioxide with surface roughness less than 1 nm and negligible optical loss. We use a process for fabricating dielectric metasurfaces that allows us to produce anisotropic, subwavelength-spaced dielectric nanostructures with shape birefringence. This process is capable of realizing any high-efficiency metasurface optical element, e.g., metalenses and axicons. PMID:27601634

Catenary optics for achromatic generation of perfect optical angular momentum.

PubMed

Pu, Mingbo; Li, Xiong; Ma, Xiaoliang; Wang, Yanqin; Zhao, Zeyu; Wang, Changtao; Hu, Chenggang; Gao, Ping; Huang, Cheng; Ren, Haoran; Li, Xiangping; Qin, Fei; Yang, Jing; Gu, Min; Hong, Minghui; Luo, Xiangang

2015-10-01

The catenary is the curve that a free-hanging chain assumes under its own weight, and thought to be a "true mathematical and mechanical form" in architecture by Robert Hooke in the 1670s, with nevertheless no significant phenomena observed in optics. We show that the optical catenary can serve as a unique building block of metasurfaces to produce continuous and linear phase shift covering [0, 2π], a mission that is extremely difficult if not impossible for state-of-the-art technology. Via catenary arrays, planar optical devices are designed and experimentally characterized to generate various kinds of beams carrying orbital angular momentum (OAM). These devices can operate in an ultra-broadband spectrum because the anisotropic modes associated with the spin-orbit interaction are almost independent of the incident light frequency. By combining the optical and topological characteristics, our approach would allow the complete control of photons within a single nanometric layer.

Laser-based investigations in gas turbine model combustors

NASA Astrophysics Data System (ADS)

Meier, W.; Boxx, I.; Stöhr, M.; Carter, C. D.

2010-10-01

Dynamic processes in gas turbine (GT) combustors play a key role in flame stabilization and extinction, combustion instabilities and pollutant formation, and present a challenge for experimental as well as numerical investigations. These phenomena were investigated in two gas turbine model combustors for premixed and partially premixed CH4/air swirl flames at atmospheric pressure. Optical access through large quartz windows enabled the application of laser Raman scattering, planar laser-induced fluorescence (PLIF) of OH, particle image velocimetry (PIV) at repetition rates up to 10 kHz and the simultaneous application of OH PLIF and PIV at a repetition rate of 5 kHz. Effects of unmixedness and reaction progress in lean premixed GT flames were revealed and quantified by Raman scattering. In a thermo-acoustically unstable flame, the cyclic variation in mixture fraction and its role for the feedback mechanism of the instability are addressed. In a partially premixed oscillating swirl flame, the cyclic variations of the heat release and the flow field were characterized by chemiluminescence imaging and PIV, respectively. Using phase-correlated Raman scattering measurements, significant phase-dependent variations of the mixture fraction and fuel distributions were revealed. The flame structures and the shape of the reaction zones were visualized by planar imaging of OH distribution. The simultaneous OH PLIF/PIV high-speed measurements revealed the time history of the flow field-flame interaction and demonstrated the development of a local flame extinction event. Further, the influence of a precessing vortex core on the flame topology and its dynamics is discussed.

A study of fractography in the low-temperature brittle fracture of an 18Cr-18Mn-0.7N austenitic steel

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

Liu, S.C.; Hashida, T.; Takahashi, H.

1998-03-01

The fracture mode and crack propagation behavior of brittle fracture at 77 and 4 K in an 18Cr-18Mn-0.7N austenitic stainless were investigated using optical and scanning electron microscopy. The fracture path was examined by observing the side surface in a partially ruptured specimen. The relationship of the fracture facets to the microstructures were established by observing the fracture surface and the adjacent side surface simultaneously. Three kinds of fracture facets were identified at either temperature. The first is a smooth curved intergranular fracture facet with characteristic parallel lines on it. The second is a fairly planar facet formed by partingmore » along an annealing twin boundary, a real {l_brace}111{r_brace} plane. There are three sets of parallel lines on the facet and the lines in different sets intersect at 60 deg. The third is a lamellar transgranular fracture facet with sets of parallel steps on it. Fracture propagated by the formation of microcracks on a grain boundary, annealing twin boundary, and coalescence of these cracks. The observation suggests that the ease of crack initiation and propagation along the grain boundary and the annealing twin boundary may be the main reason for the low-temperature brittleness of this steel. A mechanism for grain boundary cracking, including annealing twin boundary parting, has been discussed based on the stress concentration induced by impinging planar deformation structures on the grain boundaries.« less

Modeling texture transitions in cholesteric liquid crystal droplets

NASA Astrophysics Data System (ADS)

Selinger, Robin; Gimenez-Pinto, Vianney; Lu, Shin-Ying; Selinger, Jonathan; Konya, Andrew

2012-02-01

Cholesteric liquid crystals can be switched reversibly between planar and focal-conic textures, a property enabling their application in bistable displays, liquid crystal writing tablets, e-books, and color switching ``e-skins.'' To explore voltage-pulse induced switching in cholesteric droplets, we perform simulation studies of director dynamics in three dimensions. Electrostatics calculations are solved at each time step using an iterative relaxation method. We demonstrate that as expected, a low amplitude pulse drives the transition from planar to focal conic, while a high amplitude pulse drives the transition from focal conic back to the planar state. We use the model to explore the effects of droplet shape, aspect ratio, and anchoring conditions, with the goal of minimizing both response time and energy consumption.

A planar lens based on the electrowetting of two immiscible liquids

NASA Astrophysics Data System (ADS)

Liu, Chao-Xuan; Park, Jihwan; Choi, Jin-Woo

2008-03-01

This paper reports the development and characterization of a planar liquid lens based on electrowetting. The working concept of electrowetting two immiscible liquids is demonstrated with measurement and characterization of contact angles with regard to externally applied electric voltages. Consequently, a planar liquid lens is designed and implemented based on this competitive electrowetting. A droplet of silicone oil confined in an aqueous solution (1% KCl) works as a liquid lens. Electrowetting then controls the shape of the confined silicone oil and the focal length of the liquid lens varies depending upon an applied dc voltage. A unique feature of this lens design is the double-ring planar electrodes beneath the hydrophobic substrate. While an outer ring electrode provides an initial boundary for the silicone oil droplet, an inner ring works as the actuation electrode for the lens. Further, the planar electrodes, instead of vertical or out-of-plane wall electrodes, facilitate the integration of liquid lenses into microfluidic systems. With the voltage applied in the range of 50-250 V, the confined silicone oil droplet changed its shape and the optical magnification of a 3 mm-diameter liquid lens was clearly demonstrated. Moreover, focal lengths of liquid lenses with diameters of 2 mm, 3 mm and 4 mm were characterized, respectively. The obtained results suggest that a larger lens diameter yields a longer focal length and a wider range of focal length change in response to voltage. The demonstrated liquid lens has a simple structure and is easy to fabricate.

Direct Electrical Probing of Periodic Modulation of Zinc-Dopant Distributions in Planar Gallium Arsenide Nanowires.

PubMed

Choi, Wonsik; Seabron, Eric; Mohseni, Parsian K; Kim, Jeong Dong; Gokus, Tobias; Cernescu, Adrian; Pochet, Pascal; Johnson, Harley T; Wilson, William L; Li, Xiuling

2017-02-28

Selective lateral epitaxial (SLE) semiconductor nanowires (NWs), with their perfect in-plane epitaxial alignment, ability to form lateral complex p-n junctions in situ, and compatibility with planar processing, are a distinctive platform for next-generation device development. However, the incorporation and distribution of impurity dopants in these planar NWs via the vapor-liquid-solid growth mechanism remain relatively unexplored. Here, we present a detailed study of SLE planar GaAs NWs containing multiple alternating axial segments doped with Si and Zn impurities by metalorganic chemical vapor deposition. The dopant profile of the lateral multi-p-n junction GaAs NWs was imaged simultaneously with nanowire topography using scanning microwave impedance microscopy and correlated with infrared scattering-type near-field optical microscopy. Our results provide unambiguous evidence that Zn dopants in the periodically twinned and topologically corrugated p-type segments are preferentially segregated at twin plane boundaries, while Si impurity atoms are uniformly distributed within the n-type segments of the NWs. These results are further supported by microwave impedance modulation microscopy. The density functional theory based modeling shows that the presence of Zn dopant atoms reduces the formation energy of these twin planes, and the effect becomes significantly stronger with a slight increase of Zn concentration. This implies that the twin formation is expected to appear when a threshold planar concentration of Zn is achieved, making the onset and twin periodicity dependent on both Zn concentration and nanowire diameter, in perfect agreement with our experimental observations.

Alkali-resistant low-temperature atomic-layer-deposited oxides for optical fiber sensor overlays

NASA Astrophysics Data System (ADS)

Kosiel, K.; Dominik, M.; Ściślewska, I.; Kalisz, M.; Guziewicz, M.; Gołaszewska, K.; Niedziółka-Jonsson, J.; Bock, W. J.; Śmietana, M.

2018-04-01

This paper presents an investigation of properties of selected metallic oxides deposited at a low temperature (100 °C) by atomic layer deposition (ALD) technique, relating to their applicability as thin overlays for optical fiber sensors resistant in alkaline environments. Hafnium oxide (Hf x O y with y/x approx. 2.70), tantalum oxide (Ta x O y with y/x approx. 2.75) and zirconium oxide (Zr x O y with y/x approx. 2.07), which deposition was based, respectively, on tetrakis(ethylmethyl)hafnium, tantalum pentachloride and tetrakis(ethylmethyl)zirconium with deionized water, were tested as thin layers on planar Si (100) and glass substrates. Growth per cycle (GPC) in the ALD processes was 0.133-0.150 nm/cycle. Run-to-run GPC reproducibility of the ALD processes was best for Hf x O y (0.145 ± 0.001 nm/cycle) and the poorest for Ta x O y (0.133 ± 0.003 nm/cycle). Refractive indices n of the layers were 2.00-2.10 (at the wavelength λ = 632 nm), with negligible k value (at λ for 240-930 nm). The oxides examined by x-ray diffractometry proved to be amorphous, with only small addition of crystalline phases for the Zr x O y . The surfaces of the oxides had grainy but smooth topographies with root-mean square roughness ˜0.5 nm (at 10 × 10 μm2 area) according to atomic force microscopy. Ellipsometric measurements, by contrast, suggest rougher surfaces for the Zr x O y layers. The surfaces were also slightly rougher on the glass-based samples than on the Si-based ones. Nanohardness and Young modules were 4.90-8.64 GPa and 83.7-104.4 GPa, respectively. The tests of scratch resistance revealed better tribological properties for the Hf x O y and the Ta x O y than for the Zr x O y . The surfaces were hydrophilic, with wetting angles of 52.5°-62.9°. The planar oxides on Si, being resistive even to concentrated alkali (pH 14), proved to be significantly more alkali-resistive than Al2O3. The Ta x O y overlay was deposited on long-period grating sensor induced in optical fiber. Thanks to such an overlay the sensor proved to be long-lasting resistant when exposed to alkaline environment with a pH 9. Thereby, it also proved that it has a potential to be repeatedly reused as a regenerable optical fiber biosensor.

Fabrication and demonstration of 1 × 8 silicon-silica multi-chip switch based on optical phased array

NASA Astrophysics Data System (ADS)

Katayose, Satomi; Hashizume, Yasuaki; Itoh, Mikitaka

2016-08-01

We experimentally demonstrated a 1 × 8 silicon-silica hybrid thermo-optic switch based on an optical phased array using a multi-chip integration technique. The switch consists of a silicon chip with optical phase shifters and two silica-based planar lightwave circuit (PLC) chips composed of optical couplers and fiber connections. We adopted a rib waveguide as the silicon waveguide to reduce the coupling loss and increase the alignment tolerance for coupling between silicon and silica waveguides. As a result, we achieved a fast switching response of 81 µs, a high extinction ratio of over 18 dB and a low insertion loss of 4.9-8.1 dB including a silicon-silica coupling loss of 0.5 ± 0.3 dB at a wavelength of 1.55 µm.

Mid-infrared integrated optics: versatile hot embossing of mid-infrared glasses for on-chip planar waveguides for molecular sensing

NASA Astrophysics Data System (ADS)

Seddon, Angela B.; Abdel-Moneim, Nabil S.; Zhang, Lian; Pan, Wei J.; Furniss, David; Mellor, Christopher J.; Kohoutek, Tomas; Orava, Jiri; Wagner, Tomas; Benson, Trevor M.

2014-07-01

The versatility of hot embossing for shaping photonic components on-chip for mid-infrared (IR) integrated optics, using a hard mold, is demonstrated. Hot embossing via fiber-on-glass (FOG), thermally evaporated films, and radio frequency (RF)-sputtered films on glass are described. Mixed approaches of combined plasma etching and hot embossing increase the versatility still further for engineering optical circuits on a single platform. Application of these methodologies for fabricating molecular-sensing devices on-chip is discussed with a view to biomedical sensing. Future prospects for using photonic integration for the new field of mid-IR molecular sensing are appraised. Also, common methods of measuring waveguide optical loss are critically compared, regarding their susceptibility to artifacts which tend artificially to depress, or enhance, the waveguide optical loss.

Optics and Nonlinear Buckling Mechanics in Large-Area, Highly Stretchable Arrays of Plasmonic Nanostructures.

PubMed

Gao, Li; Zhang, Yihui; Zhang, Hui; Doshay, Sage; Xie, Xu; Luo, Hongying; Shah, Deesha; Shi, Yan; Xu, Siyi; Fang, Hui; Fan, Jonathan A; Nordlander, Peter; Huang, Yonggang; Rogers, John A

2015-06-23

Large-scale, dense arrays of plasmonic nanodisks on low-modulus, high-elongation elastomeric substrates represent a class of tunable optical systems, with reversible ability to shift key optical resonances over a range of nearly 600 nm at near-infrared wavelengths. At the most extreme levels of mechanical deformation (strains >100%), nonlinear buckling processes transform initially planar arrays into three-dimensional configurations, in which the nanodisks rotate out of the plane to form linear arrays with "wavy" geometries. Analytical, finite-element, and finite-difference time-domain models capture not only the physics of these buckling processes, including all of the observed modes, but also the quantitative effects of these deformations on the plasmonic responses. The results have relevance to mechanically tunable optical systems, particularly to soft optical sensors that integrate on or in the human body.

The development of kilohertz planar laser diagnostics for applications in high power turbulent flames

NASA Astrophysics Data System (ADS)

Slabaugh, Carson Daniel

In modern gas-turbine combustors, flame stabilization is achieved by inducing exhaust gas circulation within the flame zone through swirl-induced vortex breakdown. Swirling flows exhibit strong shear regions resulting in high turbulence and effective mixing. In combustion, these flows are characterized by complex unsteady interactions between turbulent flow structures and chemical reactions. Developments in high-resolution, quantitative, experimental measurement techniques must continue to improve fundamental understanding and support modeling efforts. This work describes the development of a gas turbine combustion experiment to support the application of advanced optical measurement techniques in flames operating at realistic engine conditions. Facility requirements are addressed, including instrumentation and control needs for remote operation when working with high energy flows. The methodology employed in the design of the optically-accessible combustion chamber is elucidated, including window considerations and thermal management of the experimental hardware under extremely high heat loads. Experimental uncertainties are also quantified. The stable operation of the experiment is validated using multiple techniques and the boundary conditions are verified. The successful prediction of operating conditions by the design analysis is documented and preliminary data is shown to demonstrate the capability of the experiment to produce high-fidelity datasets for advanced combustion research. Building on this experimental infrastructure, simultaneous measurements of velocity and scalar fields were performed in turbulent nonpremixed flames at gas turbine engine operating conditions using 5 kHz Particle-Image Velocimetry (PIV) and OH Planar Laser Induced Fluorescence (OH-PLIF). The experimental systems and the challenges associated with acquiring useful data at high pressures and high thermal powers are discussed. The quality of the particle scattering images used in the two-dimensional, two-component velocity field measurements is discussed. The effects of high flame luminosity and particle defocusing on the signal-to-noise ratio are discussed. Laser sheet absorption effects, which have been reported to be severe in many previous high pressure OH-PLIF attempts, were not observed to be significant in this work. The time-averaged peak and (spatial) mean signal to noise ratios were 12.7 and 6.3, respectively, at the flame B operating condition; 550 kW total thermal power and 1.0 MPa combustion chamber pressure. Simultaneous 5 kHz PIV and OH-PLIF measurements showed good agreement between single-shot flow-flame interactions, but unresolved, out-of-plane velocity components restricted the interpretation of the temporal context. At a 5 kHz interrogation frequency, the temporal resolution of the measurements was found to be sufficient for only the largest scales within the turbulent flame. The development of an analysis library for the extraction of physical data from highly-resolved planar measurements is also described. The resolution of the measurements, in space and time, is described with respect to the integral scales of the flow. The mean flow structure and its resultant effect on flame behavior is discussed. A method to perform mass-weighted averaging of flow variables was developed for direct comparison of turbulent flow properties between experimental measurements and computations. Conditional statistical sampling and length-scale filtering were used to elucidate details of flow-flame interactions as they pertain to sub-grid modeling in large-eddy simulations.

Tartaric acid assisted hydrothermal synthesis of different flower-like ZnO hierarchical architectures with tunable optical and oxygen vacancy-induced photocatalytic properties

NASA Astrophysics Data System (ADS)

Liu, Tingzhi; Li, Yangyang; Zhang, Hao; Wang, Min; Fei, Xiaoyan; Duo, Shuwang; Chen, Ying; Pan, Jian; Wang, Wei

2015-12-01

Different flower-like ZnO hierarchical architectures were prepared by tartaric acid assisted hydrothermal synthesis, especially four flower-like ZnO nanostructures were obtained simultaneously under the same reaction condition. The cauliflower-like ZnO is assembled by spherical shaped nanoparticles, and the chrysanthemum-like and other flower-like ZnO nanostructures are assembled by hexagonal rods/prisms with from planar to semi-pyramid, and to pyramid tips. TA acts as a capping agent and structure-directing agent during the synthesis. All ZnO possess the hexagonal wurtzite structure. The PL spectra can be tuned by changing TA concentration. XRD, PL and Raman spectra confirmed that oxygen vacancies mainly come from the ZnO surface. The flower-like samples of 1:4.5 and 1:3 with the largest aspect ratios have highest photocatalytic performance. They decompose 85% MB within 60 min. Combining PL Gaussian fitting with K, the higher content of oxygen vacancy is, the higher photocatalytic activity is. The enhanced photocatalytic performance is mainly induced by oxygen vacancy of ZnO. The possible formation mechanism, growth and change process of flower-like ZnO were proposed.

Planar measurements of soot volume fraction and OH in a JP-8 pool fire

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

Henriksen, Tara L.; Ring, Terry A.; Eddings, Eric G.

2009-07-15

The simultaneous measurement of soot volume fraction by laser induced incandescence (LII) and qualitative imaging of OH by laser induced fluorescence (LIF) was performed in a JP-8 pool fire contained in a 152 mm diameter pan. Line of sight extinction was used to calibrate the LII system in a laminar flame, and to provide an independent method of measuring average soot volume fraction in the turbulent flame. The presence of soot in the turbulent flame was found to be approximately 50% probable, resulting in high levels of optical extinction, which increased slightly through the flame from approximately 30% near themore » base, to approximately 50% at the tip. This high soot loading pushes both techniques toward their detection limit. Nevertheless, useful accuracy was obtained, with the LII measurement of apparent extinction in the turbulent flame being approximately 21% lower than a direct measurement, consistent with the influence of signal trapping. The axial and radial distributions of soot volume fraction are presented, along with PDFs of volume fraction, and new insight into the behavior of soot sheets in pool fires are sought from the simultaneous measurements of OH and LII. (author)« less

Full 3D opto-electronic simulation tool for nanotextured solar cells (Conference Presentation)

NASA Astrophysics Data System (ADS)

Michallon, Jérôme; Collin, Stéphane

2017-04-01

Increasing efforts on the photovoltaics research have recently been devoted to material savings, leading to the emergence of new designs based on nanotextured and nanowire-based solar cells. The use of small absorber volumes, light-trapping nanostructures and unconventional carrier collection schemes (radial nanowire junctions, point contacts in planar structures,…) increases the impact of surfaces recombination and induces homogeneity in the photogenerated carrier concentrations. The investigation of their impacts on the device performances need to be addressed using full 3D coupled opto-electrical modeling. In this context, we have developed a new tool for full 3D opto-electrical simulation using the most advanced optical and electrical simulation techniques. We will present an overview of its simulation capabilities and the key issues that have been solved to make it fully operational and reliable. We will provide various examples of opto-electronic simulation of (i) nanostructured solar cells with localized contacts and (ii) nanowire solar cells. We will also show how opto-electronic simulation can be used to simulate light- and electron-beam induced current (LBIC/EBIC) experiments, targeting quantitative analysis of the passivation properties of surfaces.

Advanced Laser-Based Techniques for Gas-Phase Diagnostics in Combustion and Aerospace Engineering.

PubMed

Ehn, Andreas; Zhu, Jiajian; Li, Xuesong; Kiefer, Johannes

2017-03-01

Gaining information of species, temperature, and velocity distributions in turbulent combustion and high-speed reactive flows is challenging, particularly for conducting measurements without influencing the experimental object itself. The use of optical and spectroscopic techniques, and in particular laser-based diagnostics, has shown outstanding abilities for performing non-intrusive in situ diagnostics. The development of instrumentation, such as robust lasers with high pulse energy, ultra-short pulse duration, and high repetition rate along with digitized cameras exhibiting high sensitivity, large dynamic range, and frame rates on the order of MHz, has opened up for temporally and spatially resolved volumetric measurements of extreme dynamics and complexities. The aim of this article is to present selected important laser-based techniques for gas-phase diagnostics focusing on their applications in combustion and aerospace engineering. Applicable laser-based techniques for investigations of turbulent flows and combustion such as planar laser-induced fluorescence, Raman and Rayleigh scattering, coherent anti-Stokes Raman scattering, laser-induced grating scattering, particle image velocimetry, laser Doppler anemometry, and tomographic imaging are reviewed and described with some background physics. In addition, demands on instrumentation are further discussed to give insight in the possibilities that are offered by laser flow diagnostics.

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

Friberg, Ari T.; Visser, Taco D.; Wolf, Emil

A reciprocity inequality is derived, involving the effective size of a planar, secondary, Gaussian Schell-model source and the effective angular spread of the beam that the source generates. The analysis is shown to imply that a fully spatially coherent source of that class (which generates the lowest-order Hermite-Gaussian laser mode) has certain minimal properties. (c) 2000 Optical Society of America.

Preliminary Results Obtained in Integrated Safety Analysis of NASA Aviation Safety Program Technologies

NASA Technical Reports Server (NTRS)

2000-01-01

This is a quarterly listing of unclassified AGARD and RTO technical publications NASA received and announced in the NASA STI Database. Contents include 1) Sensor Data Fusion and Integration of the Human Element; 2) Planar Optical Measurement Methods for Gas Turbine Components; 3) RTO Highlights 1998, December 1998.

Light extraction in planar light-emitting diode with nonuniform current injection: model and simulation.

PubMed

Khmyrova, Irina; Watanabe, Norikazu; Kholopova, Julia; Kovalchuk, Anatoly; Shapoval, Sergei

2014-07-20

We develop an analytical and numerical model for performing simulation of light extraction through the planar output interface of the light-emitting diodes (LEDs) with nonuniform current injection. Spatial nonuniformity of injected current is a peculiar feature of the LEDs in which top metal electrode is patterned as a mesh in order to enhance the output power of light extracted through the top surface. Basic features of the model are the bi-plane computation domain, related to other areas of numerical grid (NG) cells in these two planes, representation of light-generating layer by an ensemble of point light sources, numerical "collection" of light photons from the area limited by acceptance circle and adjustment of NG-cell areas in the computation procedure by the angle-tuned aperture function. The developed model and procedure are used to simulate spatial distributions of the output optical power as well as the total output power at different mesh pitches. The proposed model and simulation strategy can be very efficient in evaluation of the output optical performance of LEDs with periodical or symmetrical configuration of the electrodes.

Absorption Filter Based Optical Diagnostics in High Speed Flows

NASA Technical Reports Server (NTRS)

Samimy, Mo; Elliott, Gregory; Arnette, Stephen

1996-01-01

Two major regimes where laser light scattered by molecules or particles in a flow contains significant information about the flow are Mie scattering and Rayleigh scattering. Mie scattering is used to obtain only velocity information, while Rayleigh scattering can be used to measure both the velocity and the thermodynamic properties of the flow. Now, recently introduced (1990, 1991) absorption filter based diagnostic techniques have started a new era in flow visualization, simultaneous velocity and thermodynamic measurements, and planar velocity measurements. Using a filtered planar velocimetry (FPV) technique, we have modified the optically thick iodine filter profile of Miles, et al., and used it in the pressure-broaden regime which accommodates measurements in a wide range of velocity applications. Measuring velocity and thermodynamic properties simultaneously, using absorption filtered based Rayleigh scattering, involves not only the measurement of the Doppler shift, but also the spectral profile of the Rayleigh scattering signal. Using multiple observation angles, simultaneous measurement of one component velocity and thermodynamic properties in a supersonic jet were measured. Presently, the technique is being extended for simultaneous measurements of all three components of velocity and thermodynamic properties.

Quasi-optical theory of relativistic surface-wave oscillators with one-dimensional and two-dimensional periodic planar structures

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

Ginzburg, N. S.; Zaslavsky, V. Yu.; Institute of Applied Physics of Russian Academy of Sciences, 46 Ulyanov St., Nizhny Novgorod 603950

2013-11-15

Within the framework of a quasi-optical approach, we develop 2D and 3D self-consistent theory of relativistic surface-wave oscillators. Presenting the radiation field as a sum of two counter-propagating wavebeams coupled on a shallow corrugated surface, we describe formation of an evanescent slow wave. Dispersion characteristics of the evanescent wave following from this method are in good compliance with those found from the direct cst simulations. Considering excitation of the slow wave by a sheet electron beam, we simulate linear and nonlinear stages of interaction, which allows us to determine oscillation threshold conditions, electron efficiency, and output coupling. The transition frommore » the model of surface-wave oscillator operating in the π-mode regime to the canonical model of relativistic backward wave oscillator is considered. We also described a modified scheme of planar relativistic surface-wave oscillators exploiting two-dimensional periodic gratings. Additional transverse propagating waves emerging on these gratings synchronize the emission from a wide sheet rectilinear electron beam allowing realization of a Cherenkov millimeter-wave oscillators with subgigawatt output power level.« less

Rapid assessment of mid-infrared refractive index anisotropy using a prism coupler: chemical vapor deposited ZnS

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

Qiao, Hong; Lipschultz, Kristen A.; Anheier, Norman C.

2012-04-01

A state-of-the-art mid-infrared prism coupler was used to study the refractive index properties of forward-looking-infrared (FLIR) grade zinc sulfide samples prepared with unique planar grain orientations and locations with respect to the CVD growth axis. This study was motivated by prior photoluminescence and x-ray diffraction measurements that suggested refractive index may vary according to grain orientation. Measurements were conducted to provide optical dispersion and thermal index (dn/dT) data at discrete laser wavelengths between 0.633 and 10.591 {mu}m at two temperature set points (30 C and 90 C). Refractive index measurements between samples exhibited an average standard deviation comparable to themore » uncertainty of the prism coupler measurement (0.0004 refractive index units), suggesting that the variation in refractive index as a function of planar grain orientation and CVD deposition time is negligible, and should have no impact on subsequent optical designs. Measured dispersion data at mid-infrared wavelengths was found to agree well with prior published measurements.« less

Ultra-precision fabrication of high density micro-optical backbone interconnections for data center and mobile application

NASA Astrophysics Data System (ADS)

Lohmann, U.; Jahns, J.; Wagner, T.; Werner, C.

2012-10-01

A microoptical 3D interconnection scheme and fabricated samples of this fiberoptical multi-channel interconnec- tion with an actual capacity of 144 channels were shown. Additionally the aspects of micrometer-fabrication of such microoptical interconnection modules in the view of alignment-tolerances were considered. For the realiza- tion of the interconnection schemes, the approach of planar-integrated free space optics (PIFSO) is used with its well known advantages. This approach offers the potential for complex interconnectivity, and yet compact size.

Low Noise 1.2 THz SIS Receiver

NASA Technical Reports Server (NTRS)

Karpov, A.; Miller, D.; Rice, F.; Zmuidzinas, J.; Stern, J. A.; Bumble, B.; LeDuc, H. G.

2001-01-01

We present the development of a low noise superconductor insulator superconductor (SIS) mixer for the 1.1 - 1.25 THz heterodyne receiver of FIRST space radiotelescope. The quasi-optical SIS mixer has two NbTiN/AlN/Nb junctions with critical current density 30 kA/sq cm. The individual junction area is close to 0.65 square micrometers. The SIS junctions are coupled to the optical input beam through a planar double slot antenna and a Si hyperhemispherical lens. The minimum DSB receiver noise temperature is 650 K, about 12 hv/k.

Waveguide-based optical chemical sensor

DOEpatents

Grace, Karen M [Ranchos de Taos, NM; Swanson, Basil I [Los Alamos, NM; Honkanen, Seppo [Tucson, AZ

2007-03-13

The invention provides an apparatus and method for highly selective and sensitive chemical sensing. Two modes of laser light are transmitted through a waveguide, refracted by a thin film host reagent coating on the waveguide, and analyzed in a phase sensitive detector for changes in effective refractive index. Sensor specificity is based on the particular species selective thin films of host reagents which are attached to the surface of the planar optical waveguide. The thin film of host reagents refracts laser light at different refractive indices according to what species are forming inclusion complexes with the host reagents.

Sm 3+-doped polymer optical waveguide amplifiers

NASA Astrophysics Data System (ADS)

Huang, Lihui; Tsang, Kwokchu; Pun, Edwin Yue-Bun; Xu, Shiqing

2010-04-01

Trivalent samarium ion (Sm 3+) doped SU8 polymer materials were synthesized and characterized. Intense red emission at 645 nm was observed under UV laser light excitation. Spectroscopic investigations show that the doped materials are suitable for realizing planar optical waveguide amplifiers. About 100 μm wide multimode Sm 3+-doped SU8 channel waveguides were fabricated using a simple UV exposure process. At 250 mW, 351 nm UV pump power, a signal enhancement of ˜7.4 dB at 645 nm was obtained for a 15 mm long channel waveguide.

Aberration-free ultrathin flat lenses and axicons at telecom wavelengths based on plasmonic metasurfaces.

PubMed

Aieta, Francesco; Genevet, Patrice; Kats, Mikhail A; Yu, Nanfang; Blanchard, Romain; Gaburro, Zeno; Capasso, Federico

2012-09-12

The concept of optical phase discontinuities is applied to the design and demonstration of aberration-free planar lenses and axicons, comprising a phased array of ultrathin subwavelength-spaced optical antennas. The lenses and axicons consist of V-shaped nanoantennas that introduce a radial distribution of phase discontinuities, thereby generating respectively spherical wavefronts and nondiffracting Bessel beams at telecom wavelengths. Simulations are also presented to show that our aberration-free designs are applicable to high-numerical aperture lenses such as flat microscope objectives.

The large-area hybrid-optics RICH detector for the CLAS12 spectrometer

NASA Astrophysics Data System (ADS)

Mirazita, M.; Angelini, G.; Balossino, I.; Barion, L.; Bailey, K.; Benmokhtar, F.; Brooks, W.; Cisbani, E.; Contalbrigo, M.; Cuevas, C.; Hafidi, K.; Kim, A.; Kubarovsky, V.; Lucherini, V.; Malaguti, R.; Montgomery, R.; Movsisyan, A.; Musico, P.; O'Connor, T.; Orecchini, D.; Pappalardo, L.; Perrino, R.; Pisano, S.; Raydo, B.; Rossi, P.; Squerzanti, S.; Tomassini, S.; Turisini, M.

2017-12-01

A large area imaging Cherenkov detector is under construction to provide hadron identification in the momentum range between 3 and 8 GeV/c for the CLAS12 exeperiment at the new 12 GeV electron beam of the Jefferson Laboratory (JLab). The detector adopts a hybrid optics solution with aerogel radiator, light planar and spherical mirrors and highly-segmented photon detectors. Cherenkov photons will be imaged either directly (for forward tracks) or after two mirror reflections (large angle tracks). The status of the detector construction is here reported.

Three-dimensional, time-dependent simulation of free-electron lasers with planar, helical, and elliptical undulators

NASA Astrophysics Data System (ADS)

Freund, H. P.; van der Slot, P. J. M.; Grimminck, D. L. A. G.; Setija, I. D.; Falgari, P.

2017-02-01

Free-electron lasers (FELs) have been built ranging in wavelength from long-wavelength oscillators using partial wave guiding through ultraviolet through hard x-ray that are either seeded or start from noise. In addition, FELs that produce different polarizations of the output radiation ranging from linear through elliptic to circular polarization are currently under study. In this paper, we develop a three-dimensional, time-dependent formulation that is capable of modeling this large variety of FEL configurations including different polarizations. We employ a modal expansion for the optical field, i.e., a Gaussian expansion with variable polarization for free-space propagation. This formulation uses the full Newton-Lorentz force equations to track the particles through the optical and magnetostatic fields. As a result, arbitrary three-dimensional representations for different undulator configurations are implemented, including planar, helical, and elliptical undulators. In particular, we present an analytic model of an APPLE-II undulator to treat arbitrary elliptical polarizations, which is used to treat general elliptical polarizations. To model oscillator configurations, and allow propagation of the optical field outside the undulator and interact with optical elements, we link the FEL simulation with the optical propagation code OPC. We present simulations using the APPLE-II undulator model to produce elliptically polarized output radiation, and present a detailed comparison with recent experiments using a tapered undulator configuration at the Linac Coherent Light Source. Validation of the nonlinear formation is also shown by comparison with experimental results obtained in the Sorgente Pulsata Auto-amplificata di Radiazione Coerente SASE FEL experiment at ENEA Frascati, a seeded tapered amplifier experiment at Brookhaven National Laboratory, and the 10 kW upgrade oscillator experiment at the Thomas Jefferson National Accelerator Facility.

Nondestructive determination of the depth of planar p-n junctions by scanning electron microscopy

NASA Technical Reports Server (NTRS)

Chi, J.-Y.; Gatos, H. C.

1977-01-01

A method was developed for measuring nondestructively the depth of planar p-n junctions in simple devices as well as in integrated-circuit structures with the electron-beam induced current (EBIC) by scanning parallel to the junction in a scanning electron microscope (SEM). The results were found to be in good agreement with those obtained by the commonly used destructive method of lapping at an angle to the junction and staining to reveal the junction.

Formation of gallium nitride templates and freestanding substrates by hydride vapor phase epitaxy for homoepitaxial growth of III-nitride devices

NASA Astrophysics Data System (ADS)

Williams, Adrian Daniel

Gallium nitride (GaN) is a direct wide band gap semiconductor currently under heavy development worldwide due to interest in its applications in ultra-violet optoelectronics, power electronics, devices operating in harsh environments (high temperature or corrorsive), etc. While a number of devices have been demonstrated with this material and its related alloys, the unavailability of GaN substrates is seen as one of the current major bottlenecks to both material quality and device performance. This dissertation is concerned with the synthesis of high quality GaN substrates by the hydride vapor phase epitaxy method (HVPE). In this work, the flow of growth precursors in a home-built HVPE reactor was modeled by the Navier-Stokes equation and solved by finite element analysis to promote uniformity of GaN on 2'' sapphire substrates. Kinetics of growth was studied and various regimes of growth were identified to establish a methodology for HVPE GaN growth, independent of reactor geometry. GaN templates as well as bulk substrates were fabricated in this work. Realization of freestanding GaN substrates was achieved through discovery of a natural stress-induced method of separating bulk GaN from sapphire via mechanical failure of a low-temperature GaN buffer layer. Such a process eliminates the need for pre- or post-processing of sapphire substrates, as is currently the standard. Stress in GaN-on-sapphire is discussed, with the dominant contributor identified as thermal stress due to thermal expansion coefficient mismatch between the two materials. This thermal stress is analyzed using Stoney's equation and conditions for crack-free growth of thick GaN substrates were identified. An etch-back process for planarizing GaN templates was also developed and successfully applied to rough GaN templates. The planarization of GaN has been mainly addressed by chemo-mechanical polishing (CMP) methods in the literature, with notable shortcomings including the inability to effectively planarize gallium-polar GaN, the preferred growth plane for devices. The process developed in this work bypasses the constraints of CMP, allowing for the planarization of all surfaces of GaN irrespective of crystal orientation. The GaN samples grown for this dissertation were studied by various techniques to characterize their structural, optical, and electrical properties.

New Planar Wire Array Experiments on the LTD Generator at U Michigan

NASA Astrophysics Data System (ADS)

Weller, M. E.; Safronova, A. S.; Kantsyrev, V. L.; Shrestha, I.; Shlyaptseva, V. V.; Cooper, M. C.; Lorance, M. Y.; Stafford, A.; Petkov, E. E.; Jordan, N. M.; Patel, S. G.; Steiner, A. M.; Yager-Elorriaga, D. A.; Gilgenbach, R. M.

2014-10-01

Experiments on planar wire array z-pinches have been carried out on the MAIZE Linear Transformer Driver (LTD) generator at the University of Michigan (UM) for the first time. Specifically, Al (Al 5056, 95% Al, 5% Mg) double planar wire arrays (DPWAs) comprising six wires in each plane with interplanar gaps of 3.0 mm and 6.0 mm and interwire gaps of 0.7 mm and 1.0 mm were imploded with x-ray time-integrated spectra indicating electron temperatures of over 450 eV for K-shell Al and Mg, while producing mostly optically thin lines. In addition to x-ray time-integrated spectra, the diagnostics included x-ray time-integrated pinhole cameras, two silicon diodes, and shadowgraphy, which are analyzed and compared. The MAIZE LTD is capable of supplying up 1.0 MA, 100 kV pulses with 100 ns rise time into a matched load. However, for these experiments the LTD was charged to +-70 kV resulting in up to 0.5 MA with a current rise time of approximately 150 ns. Future experiments and the importance of studying planar wire arrays on LTD devices are discussed. This work supported by NNSA under DOE Cooperative Agreement DE-NA0001984. S. Patel & A. Steiner supported by Sandia. D. Yager-Elorriaga supported by NSF GF.

Ultrafast carrier dynamics in GaN/InGaN multiple quantum wells nanorods

NASA Astrophysics Data System (ADS)

Chen, Weijian; Wen, Xiaoming; Latzel, Michael; Yang, Jianfeng; Huang, Shujuan; Shrestha, Santosh; Patterson, Robert; Christiansen, Silke; Conibeer, Gavin

2018-01-01

GaN/InGaN multiple quantum wells (MQW) is a promising material for high-efficiency solid-state lighting. Ultrafast optical pump-probe spectroscopy is an important characterization technique for examining fundamental phenomena in semiconductor nanostructure with sub-picosecond resolution. In this study, ultrafast exciton and charge carrier dynamics in GaN/InGaN MQW planar layer and nanorod are investigated using femtosecond transient absorption (TA) techniques at room temperature. Here nanorods are fabricated by etching the GaN/InGaN MQW planar layers using nanosphere lithography and reactive ion etching. Photoluminescence efficiency of the nanorods have been proved to be much higher than that of the planar layers, but the mechanism of the nanorod structure improvement of PL efficiency is not adequately studied. By comparing the TA profile of the GaN/InGaN MQW planar layers and nanorods, the impact of surface states and nanorods lateral confinement in the ultrafast carrier dynamics of GaN/InGaN MQW is revealed. The nanorod sidewall surface states have a strong influence on the InGaN quantum well carrier dynamics. The ultrafast relaxation processes studied in this GaN/InGaN MQW nanostructure is essential for further optimization of device application.

Two-dimensional numerical simulation of boron diffusion for pyramidally textured silicon

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

Ma, Fa-Jun, E-mail: Fajun.Ma@nus.edu.sg; Duttagupta, Shubham; Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576

2014-11-14

Multidimensional numerical simulation of boron diffusion is of great relevance for the improvement of industrial n-type crystalline silicon wafer solar cells. However, surface passivation of boron diffused area is typically studied in one dimension on planar lifetime samples. This approach neglects the effects of the solar cell pyramidal texture on the boron doping process and resulting doping profile. In this work, we present a theoretical study using a two-dimensional surface morphology for pyramidally textured samples. The boron diffusivity and segregation coefficient between oxide and silicon in simulation are determined by reproducing measured one-dimensional boron depth profiles prepared using different boronmore » diffusion recipes on planar samples. The established parameters are subsequently used to simulate the boron diffusion process on textured samples. The simulated junction depth is found to agree quantitatively well with electron beam induced current measurements. Finally, chemical passivation on planar and textured samples is compared in device simulation. Particularly, a two-dimensional approach is adopted for textured samples to evaluate chemical passivation. The intrinsic emitter saturation current density, which is only related to Auger and radiative recombination, is also simulated for both planar and textured samples. The differences between planar and textured samples are discussed.« less

Self-induced redox cycling coupled luminescence on nanopore recessed disk-multiscale bipolar electrodes

DOE PAGES

Ma, Chaoxiong; Zaino III, Lawrence P.; Bohn, Paul W.

2015-03-25

Self-induced redox cycling at nanopore ring-disk electrodes is coupled, through a bipolar electrode, to a remote fluorigenic reporter reaction. We present a new configuration for coupling fluorescence microscopy and voltammetry using self-induced redox cycling for ultrasensitive electrochemical measurements. An array of nanopores, each supporting a recessed disk electrode separated by 100 nm in depth from a planar multiscale bipolar top electrode, was fabricated using multilayer deposition, nanosphere lithography, and reactive-ion etching. Self-induced redox cycling was induced on the disk electrode producing ~30× current amplification, which was independently confirmed by measuring induced electrogenerated chemiluminescence from Ru(bpy) 3 2/3+/tri-n-propylamine on the floatingmore » bipolar electrode. In this design, redox cycling occurs between the recessed disk and the top planar portion of a macroscopic thin film bipolar electrode in each nanopore. Electron transfer also occurs on a remote (mm-distance) portion of the planar bipolar electrode to maintain electroneutrality. This couples the electrochemical reactions of the target redox pair in the nanopore array with a reporter, such as a potential-switchable fluorescent indicator, in the cell at the distal end of the bipolar electrode. Oxidation or reduction of reversible analytes on the disk electrodes were accompanied by reduction or oxidation, respectively, on the nanopore portion of the bipolar electrode and then monitored by the accompanying oxidation of dihydroresorufin or reduction of resorufin at the remote end of the bipolar electrode, respectively. In both cases, changes in fluorescence intensity were triggered by the reaction of the target couple on the disk electrode, while recovery was largely governed by diffusion of the fluorescent indicator. Reduction of 1 nM of Ru(NH 3) 6 3+ on the nanoelectrode array was detected by monitoring the fluorescence intensity of resorufin, demonstrating high sensitivity fluorescence-mediated electrochemical sensing coupled to self-induced redox cycling.« less

Self-induced redox cycling coupled luminescence on nanopore recessed disk-multiscale bipolar electrodes

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

Ma, Chaoxiong; Zaino III, Lawrence P.; Bohn, Paul W.

Self-induced redox cycling at nanopore ring-disk electrodes is coupled, through a bipolar electrode, to a remote fluorigenic reporter reaction. We present a new configuration for coupling fluorescence microscopy and voltammetry using self-induced redox cycling for ultrasensitive electrochemical measurements. An array of nanopores, each supporting a recessed disk electrode separated by 100 nm in depth from a planar multiscale bipolar top electrode, was fabricated using multilayer deposition, nanosphere lithography, and reactive-ion etching. Self-induced redox cycling was induced on the disk electrode producing ~30× current amplification, which was independently confirmed by measuring induced electrogenerated chemiluminescence from Ru(bpy) 3 2/3+/tri-n-propylamine on the floatingmore » bipolar electrode. In this design, redox cycling occurs between the recessed disk and the top planar portion of a macroscopic thin film bipolar electrode in each nanopore. Electron transfer also occurs on a remote (mm-distance) portion of the planar bipolar electrode to maintain electroneutrality. This couples the electrochemical reactions of the target redox pair in the nanopore array with a reporter, such as a potential-switchable fluorescent indicator, in the cell at the distal end of the bipolar electrode. Oxidation or reduction of reversible analytes on the disk electrodes were accompanied by reduction or oxidation, respectively, on the nanopore portion of the bipolar electrode and then monitored by the accompanying oxidation of dihydroresorufin or reduction of resorufin at the remote end of the bipolar electrode, respectively. In both cases, changes in fluorescence intensity were triggered by the reaction of the target couple on the disk electrode, while recovery was largely governed by diffusion of the fluorescent indicator. Reduction of 1 nM of Ru(NH 3) 6 3+ on the nanoelectrode array was detected by monitoring the fluorescence intensity of resorufin, demonstrating high sensitivity fluorescence-mediated electrochemical sensing coupled to self-induced redox cycling.« less

Semiclassical analysis of spectral singularities and their applications in optics

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

Mostafazadeh, Ali

2011-08-15

Motivated by possible applications of spectral singularities in optics, we develop a semiclassical method of computing spectral singularities. We use this method to examine the spectral singularities of a planar slab gain medium whose gain coefficient varies due to the exponential decay of the intensity of the pumping beam inside the medium. For both singly and doublypumped samples, we obtain universal upper bounds on the decay constant beyond which no lasing occurs. Furthermore, we show that the dependence of the wavelength of the spectral singularities on the value of the decay constant is extremely mild. This is an indication ofmore » the stability of optical spectral singularities.« less

Prototype Focal-Plane-Array Optoelectronic Image Processor

NASA Technical Reports Server (NTRS)

Fang, Wai-Chi; Shaw, Timothy; Yu, Jeffrey

1995-01-01

Prototype very-large-scale integrated (VLSI) planar array of optoelectronic processing elements combines speed of optical input and output with flexibility of reconfiguration (programmability) of electronic processing medium. Basic concept of processor described in "Optical-Input, Optical-Output Morphological Processor" (NPO-18174). Performs binary operations on binary (black and white) images. Each processing element corresponds to one picture element of image and located at that picture element. Includes input-plane photodetector in form of parasitic phototransistor part of processing circuit. Output of each processing circuit used to modulate one picture element in output-plane liquid-crystal display device. Intended to implement morphological processing algorithms that transform image into set of features suitable for high-level processing; e.g., recognition.

Enhanced Optical Transmission Mediated by Localized Plasmons in Anisotropic, 3D Nanohole Arrays

PubMed Central

Yang, Jiun-Chan; Gao, Hanwei; Suh, Jae Yong; Zhou, Wei; Lee, Min Hyung; Odom, Teri W.

2010-01-01

This paper describes 3D nanohole arrays whose high optical transmission is mediated more by localized surface plasmon (LSP) excitations than by surface plasmon polaritons (SPPs). First, LSPs on 3D hole arrays lead to optical transmission an order of magnitude higher than 2D planar hole arrays. Second, LSP-mediated transmission is broadband and more tunable than SPP-enhanced transmission which is restricted by Bragg coupling. Third, for the first time, two types of surface plasmons can be selectively excited and manipulated on the same plasmonic substrate. This new plasmonic substrate fabricated by high-throughput nanolithography techniques paves the way for cutting-edge optoelectronic and biomedical applications. PMID:20698633