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Sample records for laser triggered single

  1. High on/off ratio nanosecond laser pulses for a triggered single-photon source

    NASA Astrophysics Data System (ADS)

    Jin, Gang; Liu, Bei; He, Jun; Wang, Junmin

    2016-07-01

    An 852 nm nanosecond laser pulse chain with a high on/off ratio is generated by chopping a continuous-wave laser beam using a Mach–Zehnder-type electro-optic intensity modulator (MZ-EOIM). The detailed dependence of the MZ-EOIM’s on/off ratio on various parameters is characterized. By optimizing the incident beam polarization and stabilizing the MZ-EOIM temperature, a static on/off ratio of 12600:1 is achieved. The dynamic on/off ratios versus the pulse repetition rate and the pulse duty cycle are measured and discussed. The high-on/off-ratio nanosecond pulsed laser system was used in a triggered single-photon source based on a trapped single cesium atom, which reveals clear antibunching.

  2. Laser-triggered vacuum switch

    DOEpatents

    Brannon, Paul J.; Cowgill, Donald F.

    1990-01-01

    A laser-triggered vacuum switch has a material such as a alkali metal halide on the cathode electrode for thermally activated field emission of electrons and ions upon interaction with a laser beam, the material being in contact with the cathode with a surface facing the discharge gap. The material is preferably a mixture of KCl and Ti powders. The laser may either shine directly on the material, preferably through a hole in the anode, or be directed to the material over a fiber optic cable.

  3. XI UV Laser Trigger System

    SciTech Connect

    Brickeen, B.K.; Morelli, G.L.; Paiva, R.A.; Powell, C.A.; Sundvold, P.D.

    1999-01-26

    The X1 accelerator project at Sandia National Laboratory/New Mexico utilizes SF6 insulated, multi-stage, UV laser triggered gas switches. A 265 nm UV laser system was designed and built to generate eight simultaneous output pulses of 10 mJ each with a 13 nsec pulse width. A 1061 nm solid-state Nd:Cr:GSGG laser was frequency quadrupled using a two-stage doubling process. The 1061 nm fundamental laser energy was frequency doubled with a KTP crystal to 530 nm, achieving 65% conversion efficiency. The 530 nm output was frequency doubled with KD*P crystal to 265 nm, achieving conversion efficiency of 31%. The 265 nm beam pulse was split into eight parallel channels with a system of partially reflecting mirrors. Low timing jitter and stable energy output were achieved. The entire optical system was packaged into a rugged, o-ring sealed, aluminum structure 10''x19''x2.75''. The size of the electronics was 12''x8''x8''. Subsequent accelerator system requirements dictated a redesign of the triggering system for an output beam with less angular divergence. An unstable, crossed porro prism resonator was designed and incorporated into the system. The beam divergence of the redesigned system was successfully decreased to 0.97 mrad in the UV. The resulting frequency doubling efficiencies were 55% to 530 nm and 25% to 265 nm. The optical output remained at 10 mJ in each channel with an 11 nsec pulse width.

  4. Photoconductive semiconductor switches: Laser Q-switch trigger and switch-trigger laser integration

    SciTech Connect

    Loubriel, G.M.; Mar, A.; Hamil, R.A.; Zutavern, F.J.; Helgeson, W.D.

    1997-12-01

    This report provides a summary of the Pulser In a Chip 9000-Discretionary LDRD. The program began in January of 1997 and concluded in September of 1997. The over-arching goal of this LDRD is to study whether laser diode triggered photoconductive semiconductor switches (PCSS) can be used to activate electro-optic devices such as Q-switches and Pockels cells and to study possible laser diode/switch integration. The PCSS switches we used were high gain GaAs switches because they can be triggered with small amounts of laser light. The specific goals of the LDRD were to demonstrate: (1) that small laser diode arrays that are potential candidates for laser-switch integration will indeed trigger the PCSS switch, and (2) that high gain GaAs switches can be used to trigger optical Q-switches in lasers such as the lasers to be used in the X-1 Advanced Radiation Source and the laser used for direct optical initiation (DOI) of explosives. The technology developed with this LDRD is now the prime candidate for triggering the Q switch in the multiple lasers in the laser trigger system of the X-1 Advanced Radiation Source and may be utilized in other accelerators. As part of the LDRD we developed a commercial supplier. To study laser/switch integration we tested triggering the high gain GaAs switches with: edge emitting laser diodes, vertical cavity surface emitting lasers (VCSELs), and transverse junction stripe (TJS) lasers. The first two types of lasers (edge emitting and VCSELs) did activate the PCSS but are harder to integrate with the PCSS for a compact package. The US lasers, while easier to integrate with the switch, did not trigger the PCSS at the US laser power levels we used. The PCSS was used to activate the Q-switch of the compact laser to be used in the X-1 Advanced Radiation Source.

  5. Laser trigger system for the Jupiter module

    SciTech Connect

    Paiva, R.; Sundvoid, S.; Morelli, G.; Powell, C.; Hamil, R.; Corley, J.; Pankuch, P.; Law, K.; Alexander, J.

    1995-10-01

    A UV laser trigger system has been designed to trigger the eight SF6 filled high voltage switches in the Jupiter module. The system is compact and modular, allowing for approximately thirty lasers to be triggered simultaneously in the full Jupiter design. The laser will be kinematically mounted near the high voltage section to minimize the path length to the high voltage switches and decrease the sensitivity to misalignment. The laser system is specifically built for the purpose of triggering the Jupiter module. It is a 265 nm UV laser system designed to generate eight simultaneous laser pulses of 10 mJ each with a 13 nsec pulsewidth. A 1061 nm solid-state Nd:Cr:GSGG laser is frequency quadrupled with a two stage doubling process. The 1061 nm fundamental laser energy is frequency doubled with a type II KTP crystal to generate 530 nm energy. The 530 nm output is frequency doubled with a type I KD*P crystal to generate 265 nm energy. The 265 nm pulse is split into eight parallel channels with a system of partially reflecting mirrors. Low timing jitter and a stable energy output level for the system were achieved. The entire optical system was packaged in a rugged, sealed aluminum structure 10 in. {times} 19 in. {times} 2.75 in. The size of the laser electronics unit is 7 in. {times} 8 in. {times} 8 in.

  6. Investigation of UV Laser Triggered, Nanosecond, Surface Flashover Switches

    SciTech Connect

    Nunnally, W C; Neurath, R; Holmes, C; Sampayan, S; Caporaso, G

    2003-06-03

    Triggered, multi-channel, surface discharges or surface flashover switching have been investigated as a low inductance, low pulse rate switch for conducting large currents. This paper discusses the investigation of UV (355 nm) laser triggered, single channel, low inductance, ns closure and sub-ns jitter switches for applications in switching high dielectric constant, compact pulse forming lines into accelerator loads. The experimental arrangement for evaluating the switch performance and for measuring the high field dielectric constant of the pulse forming lines is presented. Experimental results of delay and jitter measurements versus optical energy on the flashover surface and dc electric field charge.

  7. Single-photon emission at a rate of 143 MHz from a deterministic quantum-dot microlens triggered by a mode-locked vertical-external-cavity surface-emitting laser

    NASA Astrophysics Data System (ADS)

    Schlehahn, A.; Gaafar, M.; Vaupel, M.; Gschrey, M.; Schnauber, P.; Schulze, J.-H.; Rodt, S.; Strittmatter, A.; Stolz, W.; Rahimi-Iman, A.; Heindel, T.; Koch, M.; Reitzenstein, S.

    2015-07-01

    We report on the realization of a quantum dot (QD) based single-photon source with a record-high single-photon emission rate. The quantum light source consists of an InGaAs QD which is deterministically integrated within a monolithic microlens with a distributed Bragg reflector as back-side mirror, which is triggered using the frequency-doubled emission of a mode-locked vertical-external-cavity surface-emitting laser (ML-VECSEL). The utilized compact and stable laser system allows us to excite the single-QD microlens at a wavelength of 508 nm with a pulse repetition rate close to 500 MHz at a pulse width of 4.2 ps. Probing the photon statistics of the emission from a single QD state at saturation, we demonstrate single-photon emission of the QD-microlens chip with g(2)(0) < 0.03 at a record-high single-photon flux of (143 ± 16) MHz collected by the first lens of the detection system. Our approach is fully compatible with resonant excitation schemes using wavelength tunable ML-VECSELs, which will optimize the quantum optical properties of the single-photon emission in terms of photon indistinguishability.

  8. Single-photon emission at a rate of 143 MHz from a deterministic quantum-dot microlens triggered by a mode-locked vertical-external-cavity surface-emitting laser

    SciTech Connect

    Schlehahn, A.; Gschrey, M.; Schnauber, P.; Schulze, J.-H.; Rodt, S.; Strittmatter, A.; Heindel, T. Reitzenstein, S.; Gaafar, M.; Vaupel, M.; Stolz, W.; Rahimi-Iman, A.; Koch, M.

    2015-07-27

    We report on the realization of a quantum dot (QD) based single-photon source with a record-high single-photon emission rate. The quantum light source consists of an InGaAs QD which is deterministically integrated within a monolithic microlens with a distributed Bragg reflector as back-side mirror, which is triggered using the frequency-doubled emission of a mode-locked vertical-external-cavity surface-emitting laser (ML-VECSEL). The utilized compact and stable laser system allows us to excite the single-QD microlens at a wavelength of 508 nm with a pulse repetition rate close to 500 MHz at a pulse width of 4.2 ps. Probing the photon statistics of the emission from a single QD state at saturation, we demonstrate single-photon emission of the QD-microlens chip with g{sup (2)}(0) < 0.03 at a record-high single-photon flux of (143 ± 16) MHz collected by the first lens of the detection system. Our approach is fully compatible with resonant excitation schemes using wavelength tunable ML-VECSELs, which will optimize the quantum optical properties of the single-photon emission in terms of photon indistinguishability.

  9. Deterministic Single-Phonon Source Triggered by a Single Photon

    NASA Astrophysics Data System (ADS)

    Söllner, Immo; Midolo, Leonardo; Lodahl, Peter

    2016-06-01

    We propose a scheme that enables the deterministic generation of single phonons at gigahertz frequencies triggered by single photons in the near infrared. This process is mediated by a quantum dot embedded on chip in an optomechanical circuit, which allows for the simultaneous control of the relevant photonic and phononic frequencies. We devise new optomechanical circuit elements that constitute the necessary building blocks for the proposed scheme and are readily implementable within the current state-of-the-art of nanofabrication. This will open new avenues for implementing quantum functionalities based on phonons as an on-chip quantum bus.

  10. Deterministic Single-Phonon Source Triggered by a Single Photon.

    PubMed

    Söllner, Immo; Midolo, Leonardo; Lodahl, Peter

    2016-06-10

    We propose a scheme that enables the deterministic generation of single phonons at gigahertz frequencies triggered by single photons in the near infrared. This process is mediated by a quantum dot embedded on chip in an optomechanical circuit, which allows for the simultaneous control of the relevant photonic and phononic frequencies. We devise new optomechanical circuit elements that constitute the necessary building blocks for the proposed scheme and are readily implementable within the current state-of-the-art of nanofabrication. This will open new avenues for implementing quantum functionalities based on phonons as an on-chip quantum bus. PMID:27341236

  11. Compact 180-kV Marx generator triggered in atmospheric air by femtosecond laser filaments

    NASA Astrophysics Data System (ADS)

    Arantchouk, L.; Point, G.; Brelet, Y.; Larour, J.; Carbonnel, J.; André, Y.-B.; Mysyrowicz, A.; Houard, A.

    2014-03-01

    We developed a compact Marx generator triggered in atmospheric air by a single femtosecond laser beam undergoing filamentation. Voltage pulses of 180 kV could be generated with a subnanosecond jitter. The same laser beam was also used to initiate simultaneously guided discharges up to 21 cm long at the output of the generator.

  12. Compact 180-kV Marx generator triggered in atmospheric air by femtosecond laser filaments

    SciTech Connect

    Arantchouk, L. Larour, J.; Point, G.; Brelet, Y.; Carbonnel, J.; André, Y.-B.; Mysyrowicz, A.; Houard, A.

    2014-03-10

    We developed a compact Marx generator triggered in atmospheric air by a single femtosecond laser beam undergoing filamentation. Voltage pulses of 180 kV could be generated with a subnanosecond jitter. The same laser beam was also used to initiate simultaneously guided discharges up to 21 cm long at the output of the generator.

  13. Dual channel formation in a laser-triggered spark gap

    NASA Astrophysics Data System (ADS)

    Kushner, M. J.; Kimura, W. D.; Ford, D. H.; Byron, S. R.

    1985-12-01

    During self-break in spark-gap switches, multiple streamers can form in close proximity to one another. The rate of expansion of these streamers is sufficiently fast that they can interact during the current pulse. To help understand how these closely spaced, expanding spark columns interact, a laser-triggered spark gap has been studied in which two parallel columns (separation 1.3 mm) are simultaneously preionized, resulting in a pair of nearly identical, axisymmetric spark columns. The spark gap (electrode separation 1.2 cm) switches a 100 ns, 40-60 kV, 12-20 kA, 1.5 Ω waterline. Interferograms of the expanding arc channels are obtained with a laser interferometer having a time and spatial resolution of 5 ns and 10 μm, respectively. Voltage and current were measured with an internal capacitive-voltage divider and a current viewing resistor. The interferograms show that for initially identical axisymmetric columns, the individual channels do not merge into a single larger axisymmetric spark column. Instead, regions of high gas density remain inside the combined column long into the recovery period. The columns also do not remain axisymmetric as they grow, indicating a long-range interaction between the channels. The voltage drop and resistance of the dual channel spark gaps changes by less than 15% from that of a single spark channel. A scaling model is presented to explain the resistance measurements and to predict the change in resistance for multichannel spark gaps.

  14. Single element laser beam shaper

    DOEpatents

    Zhang, Shukui; Michelle D. Shinn

    2005-09-13

    A single lens laser beam shaper for converting laser beams from any spatial profile to a flat-top or uniform spatial profile. The laser beam shaper includes a lens having two aspheric surfaces. The beam shaper significantly simplifies the overall structure in comparison with conventional 2-element systems and therefore provides great ease in alignment and reduction of cost.

  15. Microwave Triggered Laser Ionization of Air

    NASA Astrophysics Data System (ADS)

    Vadiee, Ehsan; Prasad, Sarita; Jerald Buchenauer, C.; Schamiloglu, Edl

    2012-10-01

    The goal of this work is to study the evolution and dynamics of plasma expansion when a high power microwave (HPM) pulse is overlapped in time and space on a very small, localized region of plasma formed by a high energy laser pulse. The pulsed Nd:YAG laser (8 ns, 600mJ, repetition rate 10 Hz) is focused to generate plasma filaments in air with electron density of 10^17/cm^3. When irradiated with a high power microwave pulse these electrons would gain enough kinetic energy and further escalate avalanche ionization of air due to elastic electron-neutral collisions thereby causing an increased volumetric discharge region. An X-band relativistic backward wave oscillator(RBWO) at the Pulsed Power,Beams and Microwaves laboratory at UNM is constructed as the microwave source. The RBWO produces a microwave pulse of maximum power 400 MW, frequency of 10.1 GHz, and energy of 6.8 Joules. Special care is being given to synchronize the RBWO and the pulsed laser system in order to achieve a high degree of spatial and temporal overlap. A photodiode and a microwave waveguide detector will be used to ensure the overlap. Also, a new shadowgraph technique with a nanosecond time resolution will be used to detect changes in the shock wave fronts when the HPM signal overlaps the laser pulse in time and space.

  16. Single mode cavity laser

    SciTech Connect

    Martin, D.W.; Levy, J.L.

    1984-01-17

    This external cavity laser utilizes an unstable resonator in conjuction with a high reflectivity stripe end mirror which is oriented substantially parallel to the plane of the maximum divergence of the laser diode output beam and whose axis is substantially parallel to the plane of the junction of the laser diode. This configuration operates with high efficiency to select only the fundamental mode of the laser diode with a minimal divergence in the output beam.

  17. Design of a timing circuit for random laser triggering on aerosol particles

    NASA Astrophysics Data System (ADS)

    Mysak, Erin R.; Dessiaterik, Yury N.; McKinney, C. J.; Miller, Roger E.; Baer, Tomas

    2006-01-01

    A versatile timing device has been developed that permits a variety of lasers, including Nd :YAG (yttrium aluminum garnet), excimer, and CO2 lasers, to be triggered at random times. The present application is to single-particle mass spectrometry, where the corresponding arrival times are random and signaled by a laser light-scattering apparatus. The timing circuit triggers the Nd :YAG laser flashlamps approximately 200μs prior to the desired laser output pulse, followed by the Q-switch triggering pulses, which can also be used to control other lasers and/or the ion extraction optics. The flashlamps are discharged ten times per second to maintain the proper heat load on the Nd :YAG laser flashlamps. If fewer than 10particles/s are detected by light-scattering apparatus, the unit sends substitute pulses to maintain the average of 10discharges/s. When the particle flux is higher than ten per second, the circuit is designed to ignore the extra particle events. A simpler version of the circuit is also described, which accepts two timing inputs and outputs a pulse for ion extraction at a preselected time.

  18. Plasmonic nanoantenna based triggered single-photon source

    NASA Astrophysics Data System (ADS)

    Straubel, J.; Filter, R.; Rockstuhl, C.; Słowik, K.

    2016-05-01

    Highly integrated single-photon sources are key components in future quantum-optical circuits. Whereas the probabilistic generation of single photons can routinely be done by now, their triggered generation is a much greater challenge. Here, we describe the triggered generation of single photons in a hybrid plasmonic device. It consists of a lambda-type quantum emitter coupled to a multimode optical nanoantenna. For moderate interaction strengths between the subsystems, the description of the quantum optical evolution can be simplified by an adiabatic elimination of the electromagnetic fields of the nanoantenna modes. This leads to an insightful analysis of the emitter's dynamics, entails the opportunity to understand the physics of the device, and to identify parameter regimes for a desired operation. Even though the approach presented in this work is general, we consider a simple exemplary design of a plasmonic nanoantenna, made of two silver nanorods, suitable for triggered generation of single photons. The investigated device realizes single photons, triggered, potentially at high rates, and using low device volumes.

  19. Pulsed Single Frequency Fiber Lasers

    NASA Astrophysics Data System (ADS)

    Jiang, Shibin

    2016-06-01

    Pulsed single frequency fiber lasers with mJ level near 1 micron, 1.55 micron and 2 micron wavelengths were demonstrated by using our proprietary highly doped fibers. These fiber lasers exhibit excellent long term stable operation with M2<1.2.

  20. Single laser beam photothermal microscopy

    NASA Astrophysics Data System (ADS)

    Heber, Andre; Selmke, Markus; Braun, Marco; Cichos, Frank

    2015-03-01

    Fluorescence microscopy provides a tool to study dynamics in softmatter materials on a molecular level. However, the observation time for fluorescent objects is limited due to bleaching. One way to overcome this limitation is the use of gold nanoparticles as labels. They are chemically inert under typical situations. These particles are selectively imaged using a modulated heating laser and a non-absorbed detection laser even in the presence of background scatterers. The absorbed power results in a localised temperature profile and to a refractive index change which only occurs for absorption. For finite thermal diffusivities the temperature profile does not instantly follow temperature changes present on the nanoparticle's surface. This results in an out-of-phase modulation of the detection laser. By exploiting the limited thermal diffusivity we show that a single laser beam being intensity modulated is enough to selectively image and quantify absorption. The use of a single laser makes photothermal microscopy easier to implement into existing microscopy setups.

  1. Triggering Excimer Lasers by Photoionization from Corona Discharges

    NASA Astrophysics Data System (ADS)

    Xiong, Zhongmin; Duffey, Thomas; Brown, Daniel; Kushner, Mark

    2009-10-01

    High repetition rate ArF (192 nm) excimer lasers are used for photolithography sources in microelectronics fabrication. In highly attaching gas mixtures, preionization is critical to obtaining stable, reproducible glow discharges. Photoionization from a separate corona discharge is one technique for preionization which triggers the subsequent electron avalanche between the main electrodes. Photoionization triggering of an ArF excimer laser sustained in multi-atmosphere Ne/Ar/F2/Xe gas mixtures has been investigated using a 2-dimensional plasma hydrodynamics model including radiation transport. Continuity equations for charged and neutral species, and Poisson's equation are solved coincident with the electron temperature with transport coefficients obtained from solutions of Boltzmann's equation. Photoionizing radiation is produced by a surface discharge which propagates along a corona-bar located adjacent to the discharge electrodes. The consequences of pulse power waveform, corona bar location, capacitance and gas mixture on uniformity, symmetry and gain of the avalanche discharge will be discussed.

  2. High voltage switch triggered by a laser-photocathode subsystem

    DOEpatents

    Chen, Ping; Lundquist, Martin L.; Yu, David U. L.

    2013-01-08

    A spark gap switch for controlling the output of a high voltage pulse from a high voltage source, for example, a capacitor bank or a pulse forming network, to an external load such as a high gradient electron gun, laser, pulsed power accelerator or wide band radar. The combination of a UV laser and a high vacuum quartz cell, in which a photocathode and an anode are installed, is utilized as triggering devices to switch the spark gap from a non-conducting state to a conducting state with low delay and low jitter.

  3. An optically-triggered semiconductor switch for high power laser beams

    SciTech Connect

    Chow, Weng W.; Warren, M.E.

    1995-04-01

    The work involves research leading to an optically triggered switch for a high power laser pulse. The switch uses a semiconductor heterostructure whose optical properties are modified by a low power laser trigger such as a laser diode. Potential applications include optical control of pulsed power systems, control of medical lasers and implementation of security features in optical warhead architectures.

  4. Effect of helium-neon laser on musculoskeletal trigger points

    SciTech Connect

    Snyder-Mackler, L.; Bork, C.; Bourbon, B.; Trumbore, D.

    1986-07-01

    Cold lasers have been proposed recently as a therapeutic tool for treating a wide variety of pathological conditions, including wounds, arthritis, orthopedic problems, and pain. These proposed therapeutic effects largely have been unsubstantiated by research. A randomized, double blind study was undertaken to ascertain the effect of a helium-neon (He-Ne) laser on the resistance of areas of skin overlying musculoskeletal trigger points. These areas usually demonstrate decreased skin resistance when compared with the surrounding tissue. Thirty patients with musculoskeletal trigger points were assigned randomly to either an experimental or a placebo group. In addition to standard physical therapy, each patient received three 15-second applications of a He-Ne laser or placebo stimulation from an identical unit that did not emit a laser. The results of a two-way analysis of covariance with one repeated measure showed a statistically significant increase (p less than .007) in skin resistance. This increase in an abnormal skin resistance pattern may accompany the resolution of pathological conditions.

  5. Single-cell biological lasers

    NASA Astrophysics Data System (ADS)

    Gather, Malte C.; Yun, Seok Hyun

    2011-07-01

    Since their invention some 50 years ago, lasers have made a tremendous impact on modern science and technology. Nevertheless, lasing has so far relied on artificial or engineered optical gain materials, such as doped crystals, semiconductors, synthetic dyes and purified gases. Here, we show that fluorescent proteins in cells are a viable gain medium for optical amplification, and report the first successful realization of biological cell lasers based on green fluorescent protein (GFP). We demonstrate in vitro protein lasers using recombinant GFP solutions and introduce a laser based on single live cells expressing GFP. On optical pumping with nanojoule/nanosecond pulses, individual cells in a high-Q microcavity produce bright, directional and narrowband laser emission, with characteristic longitudinal and transverse modes. Lasing cells remained alive even after prolonged lasing action. Light amplification and lasing from and within biological systems pave the way to new forms of intracellular sensing, cytometry and imaging.

  6. Laser Triggered Electron Injection into a Channel Guided Wakefield Accelerator

    NASA Astrophysics Data System (ADS)

    Nakamura, K.; Filip, C.

    2005-10-01

    Laser-plasma accelerators have demonstrated the generation of narrow energy spread (˜ few %) electron beams with considerable amount of charge (>100 pC). Stability of laser-plasma accelerators, as in the conventional accelerators, requires highly synchronized injection of electrons into the structured accelerating field. The Colliding Pulse Method[1] with pre-formed plasma channel guiding [2] can result in jitter-free injection in a dark-current-free accelerating structure. We report on experimental progress of laser triggered injection of electrons into a laser wakefield, where an intense laser pulse is guided by a pre-formed plasma channel. The experiments use the multi-beam, multi-terawatt Ti:Al2O3 laser at LOASIS facility of LBNL. The ignitor-heater method is used to first produce a pre-formed plasma channel in a hydrogen gas jet. Two counter propagating beams (wakefield driver:100-500mJ-50fs, injector:50-300mJ-50fs) then are focused onto the entrance of the channel. Preliminary results indicate that electron beam properties are affected by the second beam. Details of the experiment will be presented. [1]G.Fubiani, et al, Phys. Rev. E 70, 016402 (2004). [2]C.G.R. Geddes et al, Nature 431, 538 (2004). This work is supported by DoE under contract DE-AC02-05CH11231.

  7. Pulsed laser triggered high speed microfluidic fluorescence activated cell sorter†‡

    PubMed Central

    Wu, Ting-Hsiang; Chen, Yue; Park, Sung-Yong; Hong, Jason; Teslaa, Tara; Zhong, Jiang F.; Di Carlo, Dino; Teitell, Michael A.

    2014-01-01

    We report a high speed and high purity pulsed laser triggered fluorescence activated cell sorter (PLACS) with a sorting throughput up to 20 000 mammalian cells s−1 with 37% sorting purity, 90% cell viability in enrichment mode, and >90% purity in high purity mode at 1500 cells s−1 or 3000 beads s−1. Fast switching (30 μs) and a small perturbation volume (~90 pL) is achieved by a unique sorting mechanism in which explosive vapor bubbles are generated using focused laser pulses in a single layer microfluidic PDMS channel. PMID:22361780

  8. Triggering GaAs lock-on switches with laser diode arrays

    SciTech Connect

    Loubriel, G.M.; Buttram, M.T.; Helgeson, W.D.; McLaughlin, D.L.; O'Malley, M.W.; Zutavern, F.J. ); Rosen, A.; Stabile, P.J. )

    1990-01-01

    Laser diode arrays have been used to trigger GaAs Photoconducting Semiconductor Switches (PCSS) charged to voltages of up to 60 kV and conducting currents of 580 A. The driving forces behind the use of laser diode arrays are compactness, elimination of complicated optics, and the ability to run at high repetition rates. Laser diode arrays are compactness, elimination of complicated optics, and the ability to run at high repetition rates. Laser diode arrays can trigger GaAs at high fields as the result of a new switching mode (lock-on) with very high carrier number gain. We have achieved switching of up to 10 MW in a 60 {Omega} system, with a pulse rise time of 500 ps. At 1.2 MW we have achieved repetition rates of 1 kHz with switch rise time of 500 ps for 10{sup 5} shots. The laser diode array used for these experiments delivers a 166 W pulse. In a single shot mode we have switched 4 kA with a flash lamp pumped laser and 600 A with the 166 W array. 7 refs., 5 figs.

  9. Improvement of the atmospheric discharge laser-triggered ability using multiple pulses from a kilohertz KrF laser

    SciTech Connect

    Yamaura, Michiteru

    2005-08-15

    The potential ability of lasers to control lightning can be improved by using a train of pulses with submillisecond separations. Laser-triggered experiments in a small-scale (10-mm gap) atmospheric discharge facility show that the triggering is dramatically enhanced when a five-pulse train of sub-Joule energy is used instead of a single pulse. This effect increases rapidly as the pulse interval is reduced. It appears that at a submillisecond pulse interval, sufficient positive and negative ions survive in subsequent pulses, thus enabling easy deionization. Hence, significant plasma buildup occurs from one pulse to the next. However, this persistence of ions would appear to imply that the rate of recombination (effectively a charge transfer between ions) is considerably lower than previously believed.

  10. Laser-assisted vacuum arc extreme ultraviolet source: a comparison of picosecond and nanosecond laser triggering

    NASA Astrophysics Data System (ADS)

    Beyene, Girum A.; Tobin, Isaac; Juschkin, Larissa; Hayden, Patrick; O’Sullivan, Gerry; Sokell, Emma; Zakharov, Vassily S.; Zakharov, Sergey V.; O’Reilly, Fergal

    2016-06-01

    Extreme ultraviolet (EUV) light generation by hybrid laser-assisted vacuum arc discharge plasmas, utilizing Sn-coated rotating-disc-electrodes, was investigated. The discharge was initiated by localized ablation of the liquid tin coating of the cathode disc by a laser pulse. The laser pulse, at 1064 nm, was generated by Nd:YAG lasers with variable energy from 1 to 100 mJ per pulse. The impact of shortening the laser pulse from 7 ns to 170 ps on the EUV generation has been investigated in detail. The use of ps pulses resulted in an increase in emission of EUV radiation. With a fixed discharge energy of ~4 J, the EUV conversion efficiency tends to plateau at ~2.4  ±  0.25% for the ps laser pulses, while for the ns pulses, it saturates at ~1.7  ±  0.3%. Under similar discharge and laser energy conditions, operating the EUV source with the ps-triggering resulted also in narrower spectral profiles of the emission in comparison to ns-triggering. The results indicate an advantage in using ps-triggering in laser-assisted discharges to produce brighter plasmas required for applications such as metrology.

  11. Single mode pulsed dye laser oscillator

    DOEpatents

    Hackel, Richard P.

    1992-01-01

    A single mode pulsed dye laser oscillator is disclosed. The dye laser oscillator provides for improved power efficiency by reducing the physical dimensions of the overall laser cavity, which improves frequency selection capability.

  12. Single mode pulsed dye laser oscillator

    DOEpatents

    Hackel, R.P.

    1992-11-24

    A single mode pulsed dye laser oscillator is disclosed. The dye laser oscillator provides for improved power efficiency by reducing the physical dimensions of the overall laser cavity, which improves frequency selection capability. 6 figs.

  13. Single lens laser beam shaper

    DOEpatents

    Liu, Chuyu; Zhang, Shukui

    2011-10-04

    A single lens bullet-shaped laser beam shaper capable of redistributing an arbitrary beam profile into any desired output profile comprising a unitary lens comprising: a convex front input surface defining a focal point and a flat output portion at the focal point; and b) a cylindrical core portion having a flat input surface coincident with the flat output portion of the first input portion at the focal point and a convex rear output surface remote from the convex front input surface.

  14. Single gallium nitride nanowire lasers.

    PubMed

    Johnson, Justin C; Choi, Heon-Jin; Knutsen, Kelly P; Schaller, Richard D; Yang, Peidong; Saykally, Richard J

    2002-10-01

    There is much current interest in the optical properties of semiconductor nanowires, because the cylindrical geometry and strong two-dimensional confinement of electrons, holes and photons make them particularly attractive as potential building blocks for nanoscale electronics and optoelectronic devices, including lasersand nonlinear optical frequency converters. Gallium nitride (GaN) is a wide-bandgap semiconductor of much practical interest, because it is widely used in electrically pumped ultraviolet-blue light-emitting diodes, lasers and photodetectors. Recent progress in microfabrication techniques has allowed stimulated emission to be observed from a variety of GaN microstructures and films. Here we report the observation of ultraviolet-blue laser action in single monocrystalline GaN nanowires, using both near-field and far-field optical microscopy to characterize the waveguide mode structure and spectral properties of the radiation at room temperature. The optical microscope images reveal radiation patterns that correlate with axial Fabry-Perot modes (Q approximately 10(3)) observed in the laser spectrum, which result from the cylindrical cavity geometry of the monocrystalline nanowires. A redshift that is strongly dependent on pump power (45 meV microJ x cm(-2)) supports the idea that the electron-hole plasma mechanism is primarily responsible for the gain at room temperature. This study is a considerable advance towards the realization of electron-injected, nanowire-based ultraviolet-blue coherent light sources. PMID:12618824

  15. 3D pulsed laser-triggered high-speed microfluidic fluorescence-activated cell sorter.

    PubMed

    Chen, Yue; Wu, Ting-Hsiang; Kung, Yu-Chun; Teitell, Michael A; Chiou, Pei-Yu

    2013-11-12

    We report a 3D microfluidic pulsed laser-triggered fluorescence-activated cell sorter capable of sorting at a throughput of 23 000 cells per s with 90% purity in high-purity mode and at a throughput of 45 000 cells per s with 45% purity in enrichment mode in one stage and in a single channel. This performance is realized by exciting laser-induced cavitation bubbles in a 3D PDMS microfluidic channel to generate high-speed liquid jets that deflect detected fluorescent cells and particles focused by 3D sheath flows. The ultrafast switching mechanism (20 μs complete on-off cycle), small liquid jet perturbation volume, and three-dimensional sheath flow focusing for accurate timing control of fast (1.5 m s(-1)) passing cells and particles are three critical factors enabling high-purity sorting at high-throughput in this sorter. PMID:23844418

  16. Infrared laser pulse triggers increased singlet oxygen production in tumour cells

    NASA Astrophysics Data System (ADS)

    Sokolovski, S. G.; Zolotovskaya, S. A.; Goltsov, A.; Pourreyron, C.; South, A. P.; Rafailov, E. U.

    2013-12-01

    Photodynamic therapy (PDT) is a technique developed to treat the ever-increasing global incidence of cancer. This technique utilises singlet oxygen (1O2) generation via a laser excited photosensitiser (PS) to kill cancer cells. However, prolonged sensitivity to intensive light (6-8 weeks for lung cancer), relatively low tissue penetration by activating light (630 nm up to 4 mm), and the cost of PS administration can limit progressive PDT applications. The development of quantum-dot laser diodes emitting in the highest absorption region (1268 nm) of triplet oxygen (3O2) presents the possibility of inducing apoptosis in tumour cells through direct 3O2 --> 1O2 transition. Here we demonstrate that a single laser pulse triggers dose-dependent 1O2 generation in both normal keratinocytes and tumour cells and show that tumour cells yield the highest 1O2 far beyond the initial laser pulse exposure. Our modelling and experimental results support the development of direct infrared (IR) laser-induced tumour treatment as a promising approach in tumour PDT.

  17. Bidirectional laser triggering in highly-resistive vanadium-dioxide thin films by using a 966-nm pump laser diode

    NASA Astrophysics Data System (ADS)

    Kim, Jihoon; Kim, Bong-Jun; Yu, Bong-Ahn; Kang, Hyun Wook; Nam, Seung Yun; Oh, Junghwan; Lee, Yong Wook

    2016-01-01

    By incorporating a 966-nm pump laser diode, we realized bidirectional laser triggering in a twoterminal planar device based on a highly-resistive vanadium-dioxide (VO2) thin film grown by using the pulsed laser deposition method. Bidirectional laser triggering of up to 10 mA was achieved by directly illuminating the VO2 film with a focused infrared laser beam, and the transient responses of the laser-triggered currents were analyzed. A switching contrast between the off-state and the on-state currents was measured as ˜3571, and the rising and the falling times were measured as ˜40 and ˜20 ms, respectively, when laser pulses with a pulse width of 100 ms excited the VO2-based device.

  18. Laser triggering of water switches in terrawatt-class pulse power accelerators.

    SciTech Connect

    Woodworth, Joseph Ray; Johnson, David Lee (Titan Pulse Sciences, San Leandro, CA); Wilkins, Frank (Bechtel Nevada, Las Vegas, NV); Van De Valde, David (EG&G Technical Services, Albuquerque, NM); Sarkisov, Gennady Sergeevich; Zameroski, Nathan D.; Starbird, Robert L.

    2005-12-01

    Focused Beams from high-power lasers have been used to command trigger gas switches in pulse power accelerators for more than two decades. This Laboratory-Directed Research and Development project was aimed at determining whether high power lasers could also command trigger water switches on high-power accelerators. In initial work, we determined that focused light from three harmonics of a small pulsed Nd:YAG laser at 1064 nm, 532 nm, and 355 nm could be used to form breakdown arcs in water, with the lowest breakdown thresholds of 110 J/cm{sup 2} or 14 GW/cm{sup 2} at 532 nm in the green. In laboratory-scale laser triggering experiments with a 170-kV pulse-charged water switch with a 3-mm anode-cathode gap, we demonstrated that {approx}90 mJ of green laser energy could trigger the gap with a 1-{sigma} jitter of less than 2ns, a factor of 10 improvement over the jitter of the switch in its self breaking mode. In the laboratory-scale experiments we developed optical techniques utilizing polarization rotation of a probe laser beam to measure current in switch channels and electric field enhancements near streamer heads. In the final year of the project, we constructed a pulse-power facility to allow us to test laser triggering of water switches from 0.6- MV to 2.0 MV. Triggering experiments on this facility using an axicon lens for focusing the laser and a switch with a 740 kV self-break voltage produced consistent laser triggering with a {+-} 16-ns 1-{sigma} jitter, a significant improvement over the {+-} 24-ns jitter in the self-breaking mode.

  19. Trigger effect of infrared femtosecond laser irradiation on neoplasm in experimental cervical cancer

    NASA Astrophysics Data System (ADS)

    Gening, Tatyana; Voronova, Olga; Zolotovskii, Igor; Sysoliatin, Alexey; Dolgova, Dinara; Abakumova, Tatyana

    2013-02-01

    The present work discusses effect of infrared (IR) femtosecond laser irradiation on neoplasm of white mice with experimental cervical cancer- 5 (CC-5 on the 20th and 30th days after tumor transplantation). Tumor tissue was irradiated by femtosecond erbium doped fiber laser: the wavelength is 1.55 μm, average and peak powers are1,25 mW and 6kW, respectively, irradiation trials n=10. The average energy density (energy dose) on a tissue for two groups of animals was 0,24 J/cm2 and 0,36 J/cm2 for a single trial. Irradiation was followed by biochemical determination of LPO AOS parameters ("Lipid peroxidation-antioxidants" system): malondialdehyde (MDA), activity of superoxide dismutase (SOD), catalase and glutathione-reductase (GR), glutathione-S-transferase (GST). A subsequent morphological study of tumor tissue was performed. Mathematical analysis of data demonstrates a weak dependence of the studied parameters on energy dose. The latter implies the trigger effect of IR femtosecond laser irradiation on redox-dependent processes in neoplasm at experimental cervical cancer.

  20. Kinetic simulation studies of laser-triggering in the Z gas switch

    NASA Astrophysics Data System (ADS)

    Welch, D. R.; Rose, D. V.; Thoma, C.; Clark, R. E.; Miller, C.; Madrid, E. A.; Zimmerman, W. R.; Rambo, P. K.; Schwarz, J.; Savage, M.; Atherton, B. W.

    2013-08-01

    Advanced z-pinch accelerators require precise timing of multiple mega-ampere drivers to deliver terawatt power. The triggering of these drivers is now largely initiated by laser ionization of gas switches. In this paper, we discuss detailed fully kinetic simulation of the Z laser-triggered gas switch involving detailed finite-difference time-domain particle-in-cell Monte Carlo modeling of the trigger section of the switch. Other components of the accelerator from the Marx bank through the pulse-forming line are described as circuit elements. The simulations presented here build on a recently developed model of electro-negative gas breakdown and streamer propagation that included photons produced from de-excited neutrals. New effects include multi-photon ionization of the gas in a prescribed laser field. The simulations show the sensitivity of triggering to laser parameters including focal plane within the anode-cathode gap of the trigger section of the switch, intensity at focus, and laser pulse length. Detailed electromagnetic simulations of the trigger section with circuit modeling of the upstream and downstream components are largely in agreement with Z data and demonstrate a new capability.

  1. Kinetic simulation studies of laser-triggering in the Z gas switch

    SciTech Connect

    Welch, D. R.; Rose, D. V.; Thoma, C.; Clark, R. E.; Miller, C.; Madrid, E. A.; Zimmerman, W. R.; Rambo, P. K.; Schwarz, J.; Savage, M.; Atherton, B. W.

    2013-08-15

    Advanced z-pinch accelerators require precise timing of multiple mega-ampere drivers to deliver terawatt power. The triggering of these drivers is now largely initiated by laser ionization of gas switches. In this paper, we discuss detailed fully kinetic simulation of the Z laser-triggered gas switch involving detailed finite-difference time-domain particle-in-cell Monte Carlo modeling of the trigger section of the switch. Other components of the accelerator from the Marx bank through the pulse-forming line are described as circuit elements. The simulations presented here build on a recently developed model of electro-negative gas breakdown and streamer propagation that included photons produced from de-excited neutrals. New effects include multi-photon ionization of the gas in a prescribed laser field. The simulations show the sensitivity of triggering to laser parameters including focal plane within the anode-cathode gap of the trigger section of the switch, intensity at focus, and laser pulse length. Detailed electromagnetic simulations of the trigger section with circuit modeling of the upstream and downstream components are largely in agreement with Z data and demonstrate a new capability.

  2. Photothermal single particle microscopy using a single laser beam

    SciTech Connect

    Selmke, Markus; Heber, André; Braun, Marco; Cichos, Frank

    2014-07-07

    We introduce a single-laser-beam photothermal microscopy scheme for the detection of single absorbing nano-objects. Here, a modulated incident laser beam with a constant intensity offset serves as pump and probe beam at the same time. Using the out-of-phase scattering response of the retarded thermorefractive wave field, the method provides a selective contrast for absorbers over a possible background of scatterers. The use of a single wavelength and a single beam, considerably simplifies the setup and integration of photothermal detection in existing microscopy schemes.

  3. Multifrequency, single pass free electron laser

    DOEpatents

    Szoke, Abraham; Prosnitz, Donald

    1985-01-01

    A method for simultaneous amplification of laser beams with a sequence of frequencies in a single pass, using a relativistic beam of electrons grouped in a sequence of energies corresponding to the sequence of laser beam frequencies. The method allows electrons to pass from one potential well or "bucket" to another adjacent bucket, thus increasing efficiency of trapping and energy conversion.

  4. Optical breakdown of air triggered by femtosecond laser filaments

    NASA Astrophysics Data System (ADS)

    Polynkin, Pavel; Moloney, Jerome V.

    2011-10-01

    We report experiments on the generation of dense plasma channels in ambient air using a dual laser pulse excitation scheme. The dilute plasma produced through the filamentation of an ultraintense femtosecond laser pulse is densified via avalanche ionization driven by a co-propagating multi-Joule nanosecond pulse.

  5. Single-Event-Upset Laser Scanner With Optical Bias

    NASA Technical Reports Server (NTRS)

    Kim, Quiesup

    1992-01-01

    Light-assisted microelectronic advanced laser scanner (LAMEALS) is augmented version of microelectronic advanced laser scanner (MEALS) described in article, "Laser Scanner Tests For Single-Event Upsets", (NPO-18216). Only major difference, steady illumination from helium/neon laser, argon-ion laser, and/or other source(s) combined with pulsed dye-laser illumination of MEALS into single illuminating beam.

  6. Low-jitter, high-voltage, infrared, laser-triggered, vacuum switch

    SciTech Connect

    Earley, L.M.; Barnes, G.A.

    1991-01-01

    A laser-triggered, high-voltage vacuum switch using a triggering pellet embedded in the cathode has been developed. The switch was constructed with tungsten electrodes and used either KC1 or Poco graphite pellets. An aperture in the anode allowed the laser beam to strike the pellet on the cathode surface. Reliable triggering was achieved with only 200 {mu}J of laser energy at a wavelength of 1064 nm. The switch was operated with an A-K gap voltage ranging from 5- to 30-kV with switching currents up to 15 kA peak. The delay time of the switch vaired from 70 {plus minus} 3 ns at 25 kv to 500 {plus minus} 100 ns at 5 kV. 6 refs., 6 figs., 2 tabs.

  7. LASER TRIGGERED GAS SWITCHES UTILIZING BEAM TRANSPORT THROUGH 1 MO-cm DEIONIZED WATER.

    SciTech Connect

    Woodworth, Joseph Ray; Lehr, Jane; Blickem, James R.; Wallace, Zachariah R.; Anaya, Victor Jr; Corley, John P; Lott, John; Hodge, Keith; Zameroski, Nathan D.

    2005-11-01

    We report on the successful attempts to trigger high voltage pressurized gas switches by utilizing beam transport through 1 MO-cm deionized water. The wavelength of the laser radiation was 532 nm. We have investigated Nd: YAG laser triggering of a 6 MV, SF6 insulated gas switch for a range of laser and switch parameters. Laser wavelength of 532 nm with nominal pulse lengths of 10 ns full width half maximum (FWHM) were used to trigger the switch. The laser beam was transported through 67 cm-long cell of 1 MO-cm deionized water constructed with anti reflection UV grade fused silica windows. The laser beam was then focused to form a breakdown arc in the gas between switch electrodes. Less than 10 ns jitter in the operation of the switch was obtained for laser pulse energies of between 80-110 mJ. Breakdown arcs more than 35 mm-long were produced by using a 70 cm focusing optic.

  8. Experimental study on artificially triggered lightning using high power lasers

    SciTech Connect

    Uchida, S.; Shimada, Y.; Yasuda, H.; Yamanaka, C.; Fujita, H.; Izawa, Y.; Yamanaka, T.; Wang, D.; Kawasaki, Z.; Matsu-ura, K.; Ishikubo, Y.; Adachi, M.

    1996-05-01

    A series of laboratory experiments has been conducted to investigate the initiating effects of laser plasma channel on electrical discharge. It was confirmed that the plasma channels reduce the required electrical field strength for electrical discharges to occur by a factor of 6. A field experimental site targeting natural lightning is being prepared. The thunderstorm monitoring system and the laser and optical systems have been developed and tested against various weather conditions. The results from the laboratory experiments and field experiments will be discussed. {copyright} {ital 1996 American Institute of Physics.}

  9. Laser light triggered-activated carbon nanosystem for cancer therapy.

    PubMed

    Chu, Maoquan; Peng, Jinliang; Zhao, Jiajia; Liang, Shanlu; Shao, Yuxiang; Wu, Qiang

    2013-02-01

    Among carbon-based nanomaterials, activated carbon (AC) may be an ideal candidate as a carrier for tumor therapeutic agents. Here we found a new property of nanoscale activated carbon (NAC) with narrow size distribution, namely the rapid conversion of light to thermal energy both in vitro and in vivo. An aqueous suspension of 200 μL of NAC (1 mg/mL) exhibited a rapid temperature increase of more than 35 °C after irradiation for 20 min with a 655-nm laser; this was within the temperature range for effective tumor treatment. We demonstrated that lung cancer cells (H-1299) incubated with bamboo nano-AC (BNAC) were killed with high efficiency after laser irradiation. In addition, mouse tumors with sizes smaller than the laser spot that had been injected with BNAC disappeared after irradiation. For tumors larger than the laser spot area, the incorporation of the photosensitizer ZnPc obviously increased the tumor growth inhibition efficiency of BNAC. BNAC-ZnPc was found to exhibit a synergistic effect when photothermal and photodynamic therapies were administered in combination. These results indicated that NAC can be used for high efficiency cancer phototherapy. PMID:23228422

  10. Measurement of laser power for photo-triggered drug delivery in vivo

    NASA Astrophysics Data System (ADS)

    Wang, R.; Zhang, X. L.; Liu, F.; Zhang, Z. L.; Chen, Y. J.; Zhao, E. M.; Liu, L.

    2016-07-01

    Thus far, despite many investigations have been carried out for photo-triggered drug delivery systems, most of them suffer from an intrinsic drawback of without real-time monitoring mechanism. Incident intensity of light is a feasible parameter to monitor the drug release profiles. However, it is difficult to measure the incident laser power irradiated onto the photo-triggered carriers in drug delivery systems during in vivo therapy. We design an online measurement method based on the fluorescence intensity ratio (FIR) technique through upconversion nanoparticles. FIR value varies with temperature of sample due to the thermal effect induced by the incident laser, which validates the laser power measurement. Effects of rare earth doping concentration, as well as experimental conditions including laser spots and wavelengths on the measurement behavior were also investigated.

  11. Laser simulation of single event upsets

    SciTech Connect

    Buchner, S.P.; Wilson, D.; Kang, K.; Gill, D.; Mazer, J.A.; Raburn, W.D.; Campbell, A.B.; Knudson, A.R.

    1987-12-01

    A pulsed picosecond laser was used to produce upsets in both a commercial bipolar logic circuit and a specially designed CMOS SRAM test structure. Comparing the laser energy necessary for producing upsets in transistors that have different upset sensitivities with the single event upset (SEU) level predicted from circuit analysis showed that a picosecond laser could measure circuit sensitivity to SEUs. The technique makes it possible not only to test circuits rapidly for upset sensitivity but also, because the beam can be focussed down to a small spot size, to identify sensitive transistors.

  12. Single mode optofluidic distributed feedback dye laser

    NASA Astrophysics Data System (ADS)

    Li, Zhenyu; Zhang, Zhaoyu; Emery, Teresa; Scherer, Axel; Psaltis, Demetri

    2006-01-01

    Single frequency lasing from organic dye solutions on a monolithic poly(dimethylsiloxane) (PDMS) elastomer chip is demonstrated. The laser cavity consists of a single mode liquid core/PDMS cladding channel waveguide and a phase shifted 15th order distributed feedback (DFB) structure. A 1mM solution of Rhodamine 6G in a methanol and ethylene glycol mixture was used as the gain medium. Using 6 nanosecond 532nm Nd:YAG laser pulses as the pump light, we achieved threshold pump fluence of ~0.8mJ/cm2 and single-mode operation at pump levels up to ten times the threshold. This microfabricated dye laser provides a compact and inexpensive coherent light source for microfluidics and integrated optics covering from near UV to near IR spectral region.

  13. Single-frequency glass waveguide lasers

    NASA Astrophysics Data System (ADS)

    Taccheo, S.; Della Valle, G.; Milanese, D.

    2008-10-01

    We report results on a single-end pumped waveguide laser for sensing applications Output power in excess of 20 mW with 17% slope efficiency in robust single-frequency operation at 1533.5 nm is demonstrated. The overall laser cavity laser was 60-mm long but the active medium, an Er:Yb-doped phosphate glass, was only 9-mm long. The waveguide was fabricated by two-step Ag-Na ion-exchange technique. The overall cavity length including butt-coupled fiber- Bragg-grating mirrors was <60 mm. We also reports on recent work to reach 100-mW single-frequency output power. To extend the operation wavelength to 2-micron wavelength region we also developed new tellurite glasses. Preliminary results on glass investigation are also reported.

  14. Adsorption and Unfolding of a Single Protein Triggers Nanoparticle Aggregation

    PubMed Central

    2016-01-01

    The response of living systems to nanoparticles is thought to depend on the protein corona, which forms shortly after exposure to physiological fluids and which is linked to a wide array of pathophysiologies. A mechanistic understanding of the dynamic interaction between proteins and nanoparticles and thus the biological fate of nanoparticles and associated proteins is, however, often missing mainly due to the inadequacies in current ensemble experimental approaches. Through the application of a variety of single molecule and single particle spectroscopic techniques in combination with ensemble level characterization tools, we identified different interaction pathways between gold nanorods and bovine serum albumin depending on the protein concentration. Overall, we found that local changes in protein concentration influence everything from cancer cell uptake to nanoparticle stability and even protein secondary structure. We envision that our findings and methods will lead to strategies to control the associated pathophysiology of nanoparticle exposure in vivo. PMID:26751094

  15. Adsorption and Unfolding of a Single Protein Triggers Nanoparticle Aggregation.

    PubMed

    Dominguez-Medina, Sergio; Kisley, Lydia; Tauzin, Lawrence J; Hoggard, Anneli; Shuang, Bo; D S Indrasekara, A Swarnapali; Chen, Sishan; Wang, Lin-Yung; Derry, Paul J; Liopo, Anton; Zubarev, Eugene R; Landes, Christy F; Link, Stephan

    2016-02-23

    The response of living systems to nanoparticles is thought to depend on the protein corona, which forms shortly after exposure to physiological fluids and which is linked to a wide array of pathophysiologies. A mechanistic understanding of the dynamic interaction between proteins and nanoparticles and thus the biological fate of nanoparticles and associated proteins is, however, often missing mainly due to the inadequacies in current ensemble experimental approaches. Through the application of a variety of single molecule and single particle spectroscopic techniques in combination with ensemble level characterization tools, we identified different interaction pathways between gold nanorods and bovine serum albumin depending on the protein concentration. Overall, we found that local changes in protein concentration influence everything from cancer cell uptake to nanoparticle stability and even protein secondary structure. We envision that our findings and methods will lead to strategies to control the associated pathophysiology of nanoparticle exposure in vivo. PMID:26751094

  16. Design and investigation of a multichannel laser-triggered vacuum switch

    NASA Astrophysics Data System (ADS)

    Fan, Wenfang; He, Zhenghao; Mao, Xiaopo

    2016-03-01

    A laser-triggered vacuum switch (LTVS) is an advanced closing switch with nanosecond delay and jitter. In order to enhance hold-off voltage and extend the service lifetime of an LTVS, we designed a multichannel laser-triggered vacuum switch (MLTVS) utilizing a cone-shaped target electrode placed on the cathode platform. The fabrication and testing of the MLTVS is described in this paper. Experimental results show that the working voltage of the MLTVS with a gap distance of 12 mm is from 30 V to 20 kV. The threshold energy for triggering the switch is 0.4 mJ corresponding to a peak power density of 27.9 MW/cm2. The triggering lifetime of a spot can reach up to 18 000 shots. In addition, the relationship between triggering lifetime and target materials is analyzed using a field emission scanning electron microscope. A hypothesis of the vacuum gap's triggering mechanism is discussed based on the measured results.

  17. Experimental Characterization of a Laser-Triggered, Gas-Insulated, Spark-Gap Switch

    NASA Astrophysics Data System (ADS)

    Camacho, J. F.; Brown, D. J.; Domonkos, M. T.; Ruden, E. L.; Schmitt-Sody, A.; Lucero, A. P.; Canright, J. P.; Miner, R. L.

    2015-11-01

    We have developed an experimental test bed to characterize the performance of a laser-triggered spark-gap switch as it transitions from photoionization to current conduction. The discharge of current through the switch is triggered by a focused 532-nm wavelength beam from a Q-switched Nd:YAG laser with a pulse duration of about 10 ns. The trigger pulse is delivered along the longitudinal axis of the switch, and the focal spot can be placed anywhere along the axis of the 5-mm, gas-insulated gap between the switch electrodes. The test bed is designed to support a variety of working gases (e.g., Ar, N2, He, H2) over a range of pressures. Electrical and optical diagnostics are used to measure switch performance as a function of parameters such as charge voltage, trigger pulse energy, insulating gas pressure, and gas species. Data from our experiments will be used to determine the minimum conditions necessary to induce the breakdown and conduction of a gas-insulated electrode gap in the presence of laser-induced photoionization. The electromagnetic particle-in-cell code ICEPIC will be used to produce numerical simulations of the laser-initiated arc discharge, and the experimental data will be used to validate the calculations.

  18. A nanoscale vacuum-tube diode triggered by few-cycle laser pulses

    NASA Astrophysics Data System (ADS)

    Higuchi, Takuya; Maisenbacher, Lothar; Liehl, Andreas; Dombi, Péter; Hommelhoff, Peter

    2015-02-01

    We propose and demonstrate a nanoscale vacuum-tube diode triggered by few-cycle near-infrared laser pulses. It represents an ultrafast electronic device based on light fields, exploiting near-field optical enhancement at surfaces of two metal nanotips. The sharper of the two tips displays a stronger field-enhancement, resulting in larger photoemission yields at its surface. One laser pulse with a peak intensity of 4.7 × 1011 W/cm2 triggers photoemission of ˜16 electrons from the sharper cathode tip, while emission from the blunter anode tip is suppressed by 19 dB to ˜0.2 electrons per pulse. Thus, the laser-triggered current between two tips exhibit a rectifying behavior, in analogy to classical vacuum-tube diodes. According to the kinetic energy of the emitted electrons and the distance between the tips, the total operation time of this laser-triggered nanoscale diode is estimated to be below 1 ps.

  19. A nanoscale vacuum-tube diode triggered by few-cycle laser pulses

    SciTech Connect

    Higuchi, Takuya Hommelhoff, Peter; Maisenbacher, Lothar; Liehl, Andreas; Dombi, Péter

    2015-02-02

    We propose and demonstrate a nanoscale vacuum-tube diode triggered by few-cycle near-infrared laser pulses. It represents an ultrafast electronic device based on light fields, exploiting near-field optical enhancement at surfaces of two metal nanotips. The sharper of the two tips displays a stronger field-enhancement, resulting in larger photoemission yields at its surface. One laser pulse with a peak intensity of 4.7 × 10{sup 11 }W/cm{sup 2} triggers photoemission of ∼16 electrons from the sharper cathode tip, while emission from the blunter anode tip is suppressed by 19 dB to ∼0.2 electrons per pulse. Thus, the laser-triggered current between two tips exhibit a rectifying behavior, in analogy to classical vacuum-tube diodes. According to the kinetic energy of the emitted electrons and the distance between the tips, the total operation time of this laser-triggered nanoscale diode is estimated to be below 1 ps.

  20. EXPERIMENTS WITH UV LASER TRIGGERED SPARK GAPS IN A STACKED BLUMLEIN SYSTEM

    SciTech Connect

    Nunnally, W; Lewis, R; Allen, F; Hawkins, S; Holmes, C; Sampayan, S; Caporaso, G

    2005-05-26

    This paper discusses switch requirements from basic circuit analysis and the experimental setup, parameters, and results of an experiment to investigate the feasibility of UV laser triggering of up to 40 Blumlein lines in a very compact Stacked Blumlein Line System. In addition, the method of fabricating a very compact SBL transmission lines is presented. Then the behavior of the switch parameters in the stack when closure is initiated with a UV laser pulse is presented. Specifically, the time varying inductance and resistance of the laser initiated gas discharge channel is presented and compared with a circuit model to elucidate the switch performance.

  1. Improved laser triggering and guiding of meqavolt discharges with dual fs-ns pulses

    SciTech Connect

    Mejean, Guillaume; Ackermann, Roland; Kasparian, Jerome; Salmon, Estelle; Yu Jin; Wolf, Jean-Pierre; Rethmeier, Kay; Kalkner, Wilfried; Rohwetter, Philipp; Stelmaszczyk, Kamil; Woeste, Ludger

    2006-01-09

    We demonstrate that the capacity of ultrashort high-power laser pulses to trigger and guide high-voltage discharges can be significantly enhanced by a subsequent visible nanosecond laser pulse. The femtosecond pulse induces a bundle of filaments, which creates a conducting channel of low density and cold plasma connecting the electrodes. The subsequent laser pulse photodetaches electrons from O{sub 2}{sup -} ions in the electrode leader. The resulting electrons allow efficient heating by Joule effect in a retroaction loop, resulting in a 5% reduction of the breakdown voltage.

  2. An electrically triggered 200 kV rail-gap switch for wide aperture excimer lasers

    NASA Astrophysics Data System (ADS)

    Endoh, A.; Watanabe, S.; Watanabe, M.

    1984-03-01

    A wide aperture (7 x 7 sq cm), high output energy (5 J in KrF and 13.8 J in XeCl), UV preionized excimer laser is described. A self-breakdown rail gap was employed as an output switch with the maximum voltage and current up to 230 kV and 300 kA, respectively. To solve the switching jitter problem associated with the self-breakdown, an electrical triggering was investigated. The measured minimum switching time delay and gap closing time were 40 and 10 ns, respectively. The number of channels up to 50 was observed with a uniform distribution over the 80-cm electrode length. The triggering jitter was measured to be less than a nanosecond. The maximum operation voltage of the triggered rail gap was 200 kV. The successful trigger operation was obtained in the range 30-98 percent of the self-breakdown voltage.

  3. Observation of temporal evolution following laser triggered rf breakdown in vacuum

    NASA Astrophysics Data System (ADS)

    Shao, Jiahang; Chen, Huaibi; Du, Yingchao; Gai, Wei; Huang, Wenhui; Jing, Chunguang; Shi, Jiaru; Tang, Chuanxiang; Wang, Faya; Yan, Lixin

    2014-07-01

    Radio frequency breakdown is one of the fundamental phenomena that limits the operational performance of most of high power and high gradient vacuum rf devices. We report on experimental results of rf breakdown in an S-band photocathode gun triggered by an intensity controlled laser. Through measurement and analysis of the time dependence of the collected current at the gun exit and the stored rf energy in the cavity, one can gain insight into the time evolution of the rf breakdown process. Multiple breakdowns were observed within one rf pulse due to power flow between cells after the initial emission. Similarities of the laser-triggered breakdowns to those occurring in the course of cavity conditioning and normal operation are found by comparing the postbreakdown signals in both cases. It is shown that an intense laser can offer a more controllable and flexible method for rf breakdown studies.

  4. Power Oscillator Circuit Modeling And Redesign For The Particle Beam Fusion Accelerator II (PBFA-II) Switch Trigger Laser

    NASA Astrophysics Data System (ADS)

    Smith, David L.; Hamil, Roy A.; Prestwich, Kenneth R.; Rohwein, Gerald J.; Donovan, Guy L.; Schaub, Charles M.

    1987-05-01

    The energy output and reliability of the multi-joule, injection-locked KrF laser used to trigger the PBFA II accelerator gas switches were improved through modifications identified in modeling the Blumlein driver circuit for the power oscillator. A combination of the SCEPTRE1 network solver code and JASON2 electrostatic field code were used to model the laser pulse-forming circuit in its single-channel rail gap configuration and modified versions with three or five discrete switches across the 1.45-m-wide, water-insulated transmission line. Three regularly spaced trigatron spark gaps resulted in a more uniformly driven laser volume with lower variations in voltages (10%) and rise times (9%) along its length. With the new configuration, over 3000 shots have been recorded without a single misfire compared to an average of ---25 shots before a prefire with the original design. The gas mix and pressure had to be optimized to match a given driver pulse voltage and rise time to achieve maximum performance from the laser. We summarize the model results which led to our decision to change the Blumlein switch configuration.

  5. Single-cell and single-molecule laser biotechnology

    NASA Astrophysics Data System (ADS)

    Greulich, Karl O.; Bauer, Eckhard; Fiedler, Ursula; Hoyer, Carsten; Koenig, Karsten; Monajembashi, Shamci

    1996-01-01

    While lasers have found a wide field of application in the analysis of cells and biomolecules, their use in manipulation is less common. Now, new applications of lasers are emerging, which aim at cells and even molecules as biotechnological individuals: For example, in single cell gel electrophoresis individual cells are irradiated by UV laser pulses which cause radiation damage to DNA. When the whole cell is positioned in an electric field and the UV induced damages are converted into DNA strand breaks, the resulting DNA fragments are eluted out of the cell nucleus. Small fragments are running further than large ones. After staining of the DNA fragments, the cell has the appearance like a comet (therefore comet assay). The tail moment, a parameter quantifying the shape of the tail, gives information on the degree of DNA damage. The kinetics of DNA damage induction can be described by a type of exponential law with parameters which are related to radiation sensitivity of the DNA. A further emerging technique aims at DNA as a molecular individuum. One pivotal step for single molecule DNA analysis is single molecule handling. For that purpose, a DNA molecule is coupled to a micrometer sized polystyrene bead, either via an avidin-biotin bridge or, more specifically, by strand recognition, and labeled with fluorescence dyes such as DAPI. In order to visualize the dynamics of individual DNA molecules, highly sensitive video processing and single photon counting is required. Moving the polystyrene bead using optical tweezers, the molecule can be deformed, i.e., bent, turned or stretched. Using a laser microbeam, the same individual molecule can be cut into smaller portions.

  6. Affirmation of triggered Jovian radio emissions and their attribution to corotating radio lasers

    NASA Technical Reports Server (NTRS)

    Calvert, W.

    1985-01-01

    It is argued that the original statistical evidence for the existence of triggered radio emissions and corotating radio lasers on Jupiter remains valid notwithstanding the critique of Desch and Kaiser (1985). The Voyager radio spectrograms used to identify the triggered emissions are analyzed and the results are discussed. It is shown that the critique by Desch and Kaiser is unjustified because it is not based on the original event criteria, i.e., the correlation between the occurrence of Jovian auroral kilometric radiation and fast-drift type III solar bursts in the same frequency.

  7. Commissioning of the ATLAS High Level Trigger with single beam and cosmic rays

    NASA Astrophysics Data System (ADS)

    Di Mattia, A.; ATLAS Collaboration

    2010-04-01

    ATLAS is one of the two general-purpose detectors at the Large Hadron Collider (LHC). The trigger system is responsible for making the online selection of interesting collision events. At the LHC design luminosity of 1034 cm-2s-1 it will need to achieve a rejection factor of the order of 10-7 against random proton-proton interactions, while selecting with high efficiency events that are needed for physics analyses. After a first processing level using custom electronics based on FPGAs and ASICs, the trigger selection is made by software running on two processor farms, containing a total of around two thousand multi-core machines. This system is known as the High Level Trigger (HLT). To reduce the network data traffic and the processing time to manageable levels, the HLT uses seeded, step-wise reconstruction, aiming at the earliest possible rejection of background events. The recent LHC startup and short single-beam run provided a "stress test" of the system and some initial calibration data. Following this period, ATLAS continued to collect cosmic-ray events for detector alignment and calibration purposes. After giving an overview of the trigger design and its innovative features, this paper focuses on the experience gained from operating the ATLAS trigger with single LHC beams and cosmic-rays.

  8. A Proposal of a Single Chip Surface Detector Trigger Based on Altera CycloneTM Family

    NASA Astrophysics Data System (ADS)

    Szadkowski, Z.; Pierre Auger Collaboration

    2003-07-01

    In May 2003 the new Altera r PLD family CycloneT M appears on the market. The new chip allows significantly simplifying the construction of the surface detector trigger as well as decreasing the total costs and improving parameters. In comparison with currently approved ACEX r chips, Cyclone chips contain much bigger internal memory (a possibility of implementation of slow memory inside the PLD chip or extension of fast buffers). 1.5 V supplies the core (reduction of power consumption). The single chip allows implementing interleaving DMA mode and avoiding problems with chips synchronization. The register performance indicated by compiler is on the level 130 MHz. Such a high internal speed allows increasing the sampling frequency, which could improve a time resolution of the trigger. More resources allow implementing new kind of triggers based up on Power Spectrum Density. MegaCore r library offers DSP routies as FFT, which may be useful to recognize type of events.

  9. Gene silencing by gold nanoshell-mediated delivery and laser-triggered release of antisense oligonucleotide and siRNA.

    PubMed

    Huschka, Ryan; Barhoumi, Aoune; Liu, Qing; Roth, Jack A; Ji, Lin; Halas, Naomi J

    2012-09-25

    RNA interference (RNAi)--using antisense DNA or RNA oligonucleotides to silence activity of a specific pathogenic gene transcript and reduce expression of the encoded protein--is very useful in dissecting genetic function and holds significant promise as a molecular therapeutic. A major obstacle in achieving gene silencing with RNAi technology is the systemic delivery of therapeutic oligonucleotides. Here we demonstrate an engineered gold nanoshell (NS)-based therapeutic oligonucleotide delivery vehicle, designed to release its cargo on demand upon illumination with a near-infrared (NIR) laser. A poly-L-lysine peptide (PLL) epilayer covalently attached to the NS surface (NS-PLL) is used to capture intact, single-stranded antisense DNA oligonucleotides, or alternatively, double-stranded short-interfering RNA (siRNA) molecules. Controlled release of the captured therapeutic oligonucleotides in each case is accomplished by continuous wave NIR laser irradiation at 800 nm, near the resonance wavelength of the nanoshell. Fluorescently tagged oligonucleotides were used to monitor the time-dependent release process and light-triggered endosomal release. A green fluorescent protein (GFP)-expressing human lung cancer H1299 cell line was used to determine cellular uptake and gene silencing mediated by the NS-PLL carrying GFP gene-specific single-stranded DNA antisense oligonucleotide (AON-GFP), or a double-stranded siRNA (siRNA-GFP), in vitro. Light-triggered delivery resulted in ~47% and ~49% downregulation of the targeted GFP expression by AON-GFP and siRNA-GFP, respectively. Cytotoxicity induced by both the NS-PLL delivery vector and by laser irradiation is minimal, as demonstrated by a XTT cell proliferation assay. PMID:22862291

  10. Gene Silencing by Gold Nanoshell-Mediated Delivery and Laser-Triggered Release of Antisense Oligonucleotide and siRNA

    PubMed Central

    Huschka, Ryan; Barhoumi, Aoune; Liu, Qing; Roth, Jack A.; Ji, Lin; Halas, Naomi J.

    2013-01-01

    The approach of RNA interference (RNAi)- using antisense DNA or RNA oligonucleotides to silence activity of a specific pathogenic gene transcript and reduce expression of the encoded protein- is very useful in dissecting genetic function and holds significant promise as a molecular therapeutic. A major obstacle in achieving gene silencing with RNAi technology is the systemic delivery of therapeutic oligonucleotides. Here we demonstrate an engineered gold nanoshell (NS)-based therapeutic oligonucleotide delivery vehicle, designed to release its cargo on demand upon illumination with a near-infrared (NIR) laser. A poly(L)lysine peptide (PLL) epilayer covalently attached to the NS surface (NS-PLL) is used to capture intact, single-stranded antisense DNA oligonucleotides, or alternatively, double-stranded short-interfering RNA (siRNA) molecules. Controlled release of the captured therapeutic oligonucleotides in each case is accomplished by continuous wave NIR laser irradiation at 800 nm, near the resonance wavelength of the nanoshell. Fluorescently tagged oligonucleotides were used to monitor the time-dependent release process and light-triggered endosomal release. A green fluorescent protein (GFP)-expressing human lung cancer H1299 cell line was used to determine cellular uptake and gene silencing mediated by the NS-PLL carrying GFP gene-specific single-stranded DNA antisense oligonucleotide (AON-GFP), or a double-stranded siRNA (siRNA-GFP), in vitro. Light-triggered delivery resulted in ∼ 47% and ∼49% downregulation of the targeted GFP expression by AON-GFP and siRNA-GFP, respectively. Cytotoxicity induced by both the NS-PLL delivery vector and by laser irradiation is minimal, as demonstrated by a XTT cell proliferation assay. PMID:22862291

  11. Suppression of single-cesium-atom heating in a microscopic optical dipole trap for demonstration of an 852-nm triggered single-photon source

    NASA Astrophysics Data System (ADS)

    Liu, Bei; Jin, Gang; He, Jun; Wang, Junmin

    2016-07-01

    We investigate single-cesium-atom heating owing to the momentum accumulation process induced by the resonant pulsed excitation in a microscopic optical dipole trap formed by a strongly focused 1064-nm laser beam. The heating depends on the trap frequency, which restricts the maximum repetition rate of the pulsed excitation. We experimentally verify the heating of a single atom and then demonstrate how to suppress it with an optimized pulsed excitation and cooling method. The typical trap lifetime of a single cesium atom is extended from 108 ±6 μ s to 2536 ±31 ms , and the corresponding number of excitations increases from ˜108 to ˜360 000 . In applying this faster cooling method, we use the trapped single cesium atom as a triggered single-photon source at an excitation repetition rate of 10 MHz. The second-order intensity correlations of the emitted single photons are characterized by implementing a Hanbury Brown and Twiss setup, and a clear antibunching effect has been observed.

  12. Single event effects and laser simulation studies

    NASA Technical Reports Server (NTRS)

    Kim, Q.; Schwartz, H.; Mccarty, K.; Coss, J.; Barnes, C.

    1993-01-01

    The single event upset (SEU) linear energy transfer threshold (LETTH) of radiation hardened 64K Static Random Access Memories (SRAM's) was measured with a picosecond pulsed dye laser system. These results were compared with standard heavy ion accelerator (Brookhaven National Laboratory (BNL)) measurements of the same SRAM's. With heavy ions, the LETTH of the Honeywell HC6364 was 27 MeV-sq cm/mg at 125 C compared with a value of 24 MeV-sq cm/mg obtained with the laser. In the case of the second type of 64K SRAM, the IBM640lCRH no upsets were observed at 125 C with the highest LET ions used at BNL. In contrast, the pulsed dye laser tests indicated a value of 90 MeV-sq cm/mg at room temperature for the SEU-hardened IBM SRAM. No latchups or multiple SEU's were observed on any of the SRAM's even under worst case conditions. The results of this study suggest that the laser can be used as an inexpensive laboratory SEU prescreen tool in certain cases.

  13. Laser-Assisted Single Molecule Refolding

    NASA Astrophysics Data System (ADS)

    Zhao, Rui; Marshall, Myles; Aleman, Elvin; Lamichhane, Rajan; Rueda, David

    2010-03-01

    In vivo, many RNA molecules can adopt multiple conformations depending on their biological context such as the HIV Dimerization Initiation Sequence (DIS) or the DsrA RNA in bacteria. It is quite common that the initial interaction between the two RNAs takes place via complementary unpaired regions, thus forming a so-called kissing complex. However, the exact kinetic mechanism by which the two RNA molecules reach the dimerized state is still not well understood. To investigate the refolding energy surface of RNA molecules, we have developed new technology based on the combination of single molecule spectroscopy with laser induced temperature jump kinetics, called Laser Assisted Single-molecule Refolding (LASR). LASR enables us to induce folding reactions of otherwise kinetically trapped RNAs at the single molecule level, and to characterize their folding landscape. LASR provides an exciting new approach to study molecular memory effects and kinetically trapped RNAs in general. LASR should be readily applicable to study DNA and protein folding as well.

  14. Percutaneous Release of Trigger Fingers: Comparing Multiple Digits with Single Digit Involvement

    PubMed Central

    Saremi, Hossein; Hakhamaneshi, Elham; Rabiei, Mohamad Ali Seif

    2016-01-01

    Background: To evaluate safety and efficacy of percutaneous release of trigger finger in multiple digits involvement in comparison with single digit involvement. Method: A number of 100 patients (131 fingers) were treated by percutaneous release and divided into two groups: single digit (group A) and multiple digits (group B). They were followed up for one year. Success rate, pain, complications and duration of analgesic use were studied and then compared in both groups. Results: All patients in both groups were treated successfully without any recurrence in a one-year follow-up. No complication was observed, but postoperative duration of pain was significantly different between the two groups. Period of painkiller use was also different between the two groups. Conclusion: Percutaneous release is a safe and effective treatment for trigger fingers even if multiple digits are involved. It is also safe in thumb and index finger involvement and diabetic patients.

  15. Self-triggered method for characterization of single-photon detectors.

    PubMed

    Ferreira da Silva, Thiago

    2016-03-01

    Single-photon avalanche photodiodes (SPADs) are instruments capable of measuring light at the single-photon level. Some important features of these devices must be correctly characterized for reliable application. In this paper, I present a high-resolution self-triggered method for characterization of SPADs based on the analysis of the time intervals between consecutive detection events with the detector under continuous-wave illumination. The self-triggered method is employed for characterization of the detection dead time-a limiting feature for the maximum counting rate achievable under free-running or gated modes-and of the temporal gate width-an important parameter when the detector is operated under gated mode. The measurement results are presented and the method is experimentally validated. PMID:26974614

  16. Laser triggered injection of electrons in a laser wakefield accelerator with the colliding pulse method

    SciTech Connect

    Nakamura, K.; Fubiani, G.; Geddes, C.G.R.; Michel, P.; van Tilborg, J.; Toth, C.; Esarey, E.; Schroeder, C.B.; Leemans, W.P.

    2004-10-22

    An injection scheme for a laser wakefield accelerator that employs a counter propagating laser (colliding with the drive laser pulse, used to generate a plasma wake) is discussed. The threshold laser intensity for electron injection into the wakefield was analyzed using a heuristic model based on phase-space island overlap. Analysis shows that the injection can be performed using modest counter propagating laser intensity a{sub 1} < 0.5 for a drive laser intensity of a{sub 0} = 1.0. Preliminary experiments were preformed using a drive beam and colliding beam. Charge enhancement by the colliding pulse was observed. Increasing the signal-to-noise ratio by means of a preformed plasma channel is discussed.

  17. Single-mode tapered quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Rauter, Patrick; Menzel, Stefan; Gokden, B.; K. Goyal, Anish; Wang, Christine A.; Sanchez, Antonio; Turner, George; Capasso, Federico

    2013-05-01

    We demonstrate tapered quantum cascade lasers monolithically integrated with a distributed Bragg reflector acting as both a wavelength-selective back mirror and a transverse mode filter. Each of the 14 devices operates at a different wavelength between 9.2 and 9.7 μm, where nine devices feature single-mode operation at peak powers between 0.3 and 1.6 W at room temperature. High output power and excellent beam quality with peak brightness values up to 1.6 MW cm-2 sr-1 render these two-terminal devices highly suitable for stand-off spectroscopy applications.

  18. Triggering Mechanism for Neutron Induced Single-Event Burnout in Power Devices

    NASA Astrophysics Data System (ADS)

    Shoji, Tomoyuki; Nishida, Shuichi; Hamada, Kimimori

    2013-04-01

    Cosmic ray neutrons can trigger catastrophic failures in power devices. It has been reported that parasitic transistor action causes single-event burnout (SEB) in power metal-oxide-semiconductor field-effect transistors (MOSFETs) and insulated gate bipolar transistors (IGBTs). However, power diodes do not have an inherent parasitic transistor. In this paper, we describe the mechanism triggering SEB in power diodes for the first time using transient device simulation. Initially, generated electron-hole pairs created by incident recoil ions generate transient current, which increases the electron density in the vicinity of the n-/n+ boundary. The space charge effect of the carriers leads to an increase in the strength of the electric field at the n-/n+ boundary. Finally, the onset of impact ionization at the n-/n+ boundary can trigger SEB. Furthermore, this failure is closely related to diode secondary breakdown. It was clarified that the impact ionization at the n-/n+ boundary is a key point of the mechanism triggering SEB in power devices.

  19. Effect of triggered discharge using an excimer laser with high-repetition-rate of the order of kilohertz

    SciTech Connect

    Yamaura, Michiteru; Watanabe, Takashi; Hayashi, Nobuya; Ihara, Satoshi

    2005-03-28

    The triggering ability of the laser-triggered lightning method is improved by using a KrF excimer laser with a high-repetition-rate of the order of kHz order. It is clarified that the effect of a triggered discharge is considerably enhanced when the plasma density is greater than 10{sup 13} cm{sup -3}. Thus far, the laser-triggered lightning method has not been expected to display a triggering ability since one pulse of an excimer laser possesses energy of less than 1 J, and the produced plasma has a low density of 10{sup 12} cm{sup -3}, its plasma density is one order lower than that required for its application in the triggering and guiding of lightning discharge. The enhancement of plasma density achieved by utilizing the accumulation effect of charged particles generated by the high-repetition-rate laser was 10{sup 13} cm{sup -3}. This led to an effective a 50% reduction in the self-breakdown voltage.

  20. Single-frequency tunable laser for pumping cesium frequency standards

    SciTech Connect

    Zhuravleva, O V; Ivanov, Andrei V; Leonovich, A I; Kurnosov, V D; Kurnosov, K V; Chernov, Roman V; Shishkov, V V; Pleshanov, S A

    2006-08-31

    A single-frequency tunable laser for pumping the cesium frequency standard is studied. It is shown experimentally that the laser emits at a single frequency despite the fact that a few longitudinal modes of the external cavity fall within the reflection band of a fibre Bragg grating (FBG) written in the optical fibre. The laser wavelength can be tuned by varying the pump current of the laser, its temperature, and the FBG temperature. The laser linewidth does not exceed 2 MHz for 10 mW of output power. (lasers)

  1. Laser-triggered intraocular implant to induce photodynamic therapy for posterior capsule opacification prevention.

    PubMed

    Zhang, Zhaoguo; Huang, Wenyong; Lei, Ming; He, Yuanfeng; Yan, Mina; Zhang, Xuefei; Zhao, Chunshun

    2016-02-10

    Posterior capsule opacification (PCO) is one of the main reasons for loss of vision again after cataract surgery. In this study, intraocular lenses were modified with indocyanine green (ICG) and sealed up with PLGA to form long-term intraocular implants (ICG-IOL). When triggered by laser, ICG-IOL would induce photodynamic therapy (PDT). In-vitro cell viability assay and scratch wound healing assay demonstrated that ICG-IOL could effectively inhibit HLEpiC proliferation and migration without causing damage to the cells far away from it. Laser attenuation test indicated that ICG-IOL could be applied in vivo. In-vivo pharmacodynamics and safety study showed that ICG-IOL could significantly prevent the occurrence of PCO and was safe for intraocular normal tissue. All these results suggested that ICG-IOL would be a very promising candidate for PCO prevention. PMID:26456263

  2. Single-trapped-ion vibronic Raman laser

    NASA Astrophysics Data System (ADS)

    di Fidio, C.; Vogel, W.; de Matos Filho, R. L.; Davidovich, L.

    2002-01-01

    We propose a model for a single-trapped-ion vibronic Raman laser and study its dynamics by using quantum-trajectory methods. In our treatment, it is essential that both the cavity field of the high-finesse optical cavity and the center-of-mass vibrational motion of the trapped ion be quantized. A transition from a super-Poissonian light source to a Poissonian lasing regime is obtained by increasing the Raman coupling constant. Furthermore, we demonstrate that a nonclassical regime can be realized, where the photon statistics becomes sub-Poissonian and the photons leak out of the cavity in an antibunched manner. This is achieved by exploiting nonlinear Stark shifts inherent in the model, which depend on both the number of cavity photons and the number of vibrational quanta.

  3. Laser tweezers Raman spectroscopy of single cells

    NASA Astrophysics Data System (ADS)

    Chen, De

    Raman scattering is an inelastic collision between the vibrating molecules inside the sample and the incident photons. During this process, energy exchange takes place between the photon and the scattering molecule. By measuring the energy change of the photon, the molecular vibration mode can be probed. The vibrational spectrum contains valuable information about the disposition of atomic nuclei and chemical bonds within a molecule, the chemical compositions and the interactions between the molecule and its surroundings. In this dissertation, laser tweezers Raman spectroscopy (LTRS) technique is applied for the analysis of biological cells and human cells at single cell level. In LTRS, an individual cell is trapped in aqueous medium with laser tweezers, and Raman scattering spectra from the trapped cell are recorded in real-time. The Raman spectra of these cells can be used to reveal the dynamical processes of cell growth, cell response to environment changes, and can be used as the finger print for the identification of a bacterial cell species. Several biophysical experiments were carried out using LTRS: (1) the dynamic germination process of individual spores of Bacillus thuringiensis was detected via Ca-DPA, a spore-specific biomarker molecule; (2) inactivation and killing of Bacillus subtilis spores by microwave irradiation and wet heat were studied at single cell level; (3) the heat shock activation process of single B. subtilis spores were analyzed, in which the reversible transition from glass-like state at low temperature to liquid-like state at high temperature in spore was revealed at the molecular level; (4) the kinetic processes of bacterial cell lysis of E. coli by lysozyme and by temperature induction of lambda phage were detected real-time; (5) the fixation and rehydration of human platelets were quantitatively evaluated and characterized with Raman spectroscopy method, which provided a rapid way to quantify the quality of freeze-dried therapeutic

  4. Triggered generation of single guided photons from a single atom in a nanofiber cavity

    SciTech Connect

    Le Kien, Fam; Hakuta, K.

    2011-04-15

    We study the deterministic generation of single guided-mode photons from an atom in the vicinity of a nanofiber with two fiber-Bragg-grating (FBG) mirrors. The technique is based on a cavity-enhanced Raman scattering process involving an adiabatic passage. We take into account the scattering of the pump field from the fiber, the multilevel structure of the atom, and the surface-induced van der Waals potential in describing the photon generation process. We find that, due to the confinement of the cavity field in the transverse plane of the fiber and in the space between the FBG mirrors, the probability of the generation of a single guided-mode photon can be close to unity even when the finesse of the nanofiber cavity is moderate. We show the possibilities of saturation and power broadening in the behavior of the number of photons emitted into the nanofiber.

  5. Optical triggering of a Q-switched Nd:YAG laser via transverse bleaching of a Cr:YAG saturable absorber.

    PubMed

    Cole, Brian; Lei, Jonathan; DiLazaro, Tom; Schilling, Bradley; Goldberg, Lew

    2009-11-01

    Optical triggering via direct bleaching of a Cr:YAG saturable absorber was applied to a monolithic Nd:YAG/Cr:YAG laser crystal. The method uses a single laser diode bar to bleach a thin sheet within the saturable absorber from a direction orthogonal to the lasing axis. By placing the Q-switch at the time corresponding to the steepest slope (dT/dt) for change in transmission during bleaching, the pulse-to-pulse timing jitter showed a 13.2x reduction in standard deviation, from 132 ns for free-running operation to 10 ns with optical triggering. We measured that a fluence of 60 kW/cm(2) was sufficient to enable optical triggering, where a diode appropriately sized for the length of the Cr:YAG (approximately 3 mm) would then require only approximately 150 W of optical power over a 1-2 micros duration to enable effective jitter reduction. Additionally, we measured an increase in optical-to-optical efficiency with optical triggering, where the efficiency improved from 12% to 13.5%. PMID:19881668

  6. Linearly aligned superradiant Bose-Einstein condensates diffracted by a single short laser pulse

    NASA Astrophysics Data System (ADS)

    Inano, Ichiro; Nakamura, Keisuke; Morinaga, Atsuo

    2013-04-01

    Multiorder bidirectional superradiant Bose-Einstein condensates (BECs) were generated in a straight line by an irradiation of a single unidirectional short laser pulse along the long axis of a cigar-shaped sodium BEC in a magnetic trap. The probabilities of the diffracted BECs as a function of the laser intensity were well explained by the square of the Bessel functions and it was estimated that the intensity of the end-fire beam was 25% of the laser intensity. The backward diffractions disappeared at pulse duration longer than 5 μs because of energy conservation. The probability for the +first-order diffraction grew exponentially with pulse duration when the backward diffractions disappeared. We observed the linearly aligned diffracted BECs along the propagation direction of the laser beam, regardless of the aspect ratio of the condensates. This fact indicates that the end-fire beam is triggered by the small backreflection from the vacuum window.

  7. Single photon detection and timing in the Lunar Laser Ranging Experiment.

    NASA Technical Reports Server (NTRS)

    Poultney, S. K.

    1972-01-01

    The goals of the Lunar Laser Ranging Experiment lead to the need for the measurement of a 2.5 sec time interval to an accuracy of a nanosecond or better. The systems analysis which included practical retroreflector arrays, available laser systems, and large telescopes led to the necessity of single photon detection. Operation under all background illumination conditions required auxiliary range gates and extremely narrow spectral and spatial filters in addition to the effective gate provided by the time resolution. Nanosecond timing precision at relatively high detection efficiency was obtained using the RCA C31000F photomultiplier and Ortec 270 constant fraction of pulse-height timing discriminator. The timing accuracy over the 2.5 sec interval was obtained using a digital interval with analog vernier ends. Both precision and accuracy are currently checked internally using a triggerable, nanosecond light pulser. Future measurements using sub-nanosecond laser pulses will be limited by the time resolution of single photon detectors.

  8. A stochastic single-molecule event triggers phenotype switching of a bacterial cell.

    PubMed

    Choi, Paul J; Cai, Long; Frieda, Kirsten; Xie, X Sunney

    2008-10-17

    By monitoring fluorescently labeled lactose permease with single-molecule sensitivity, we investigated the molecular mechanism of how an Escherichia coli cell with the lac operon switches from one phenotype to another. At intermediate inducer concentrations, a population of genetically identical cells exhibits two phenotypes: induced cells with highly fluorescent membranes and uninduced cells with a small number of membrane-bound permeases. We found that this basal-level expression results from partial dissociation of the tetrameric lactose repressor from one of its operators on looped DNA. In contrast, infrequent events of complete dissociation of the repressor from DNA result in large bursts of permease expression that trigger induction of the lac operon. Hence, a stochastic single-molecule event determines a cell's phenotype. PMID:18927393

  9. A Stochastic Single-Molecule Event Triggers Phenotype Switching of a Bacterial Cell

    NASA Astrophysics Data System (ADS)

    Xie, Sunney; Choi, Paul; Cai, Long

    2009-03-01

    By monitoring fluorescently labeled lactose permease with single-molecule sensitivity, we investigated the molecular mechanism of how an Escherichia coli cell with the lac operon switches from one phenotype to another. At intermediate inducer concentrations, a population of genetically identical cells exhibits two phenotypes: induced cells with highly fluorescent membranes and uninduced cells with a small number of membrane-bound permeases. We found that this basal-level expression results from partial dissociation of the tetrameric lactose repressor from one of its operators on looped DNA. In contrast, infrequent events of complete dissociation of the repressor from DNA result in large bursts of permease expression that trigger induction of the lac operon. Hence, a stochastic single-molecule event determines a cell's phenotype.

  10. Characterization of the cellular response triggered by gold nanoparticle-mediated laser manipulation.

    PubMed

    Kalies, Stefan; Keil, Sebastian; Sender, Sina; Hammer, Susanne C; Antonopoulos, Georgios C; Schomaker, Markus; Ripken, Tammo; Murua Escobar, Hugo; Meyer, Heiko; Heinemann, Dag

    2015-11-01

    Laser-based transfection techniques have proven high applicability in several cell biologic applications. The delivery of different molecules using these techniques has been extensively investigated. In particular, new high-throughput approaches such as gold nanoparticle–mediated laser transfection allow efficient delivery of antisense molecules or proteins into cells preserving high cell viabilities. However, the cellular response to the perforation procedure is not well understood. We herein analyzed the perforation kinetics of single cells during resonant gold nanoparticle–mediated laser manipulation with an 850-ps laser system at a wavelength of 532 nm. Inflow velocity of propidium iodide into manipulated cells reached a maximum within a few seconds. Experiments based on the inflow of FM4-64 indicated that the membrane remains permeable for a few minutes for small molecules. To further characterize the cellular response postmanipulation, we analyzed levels of oxidative heat or general stress. Although we observed an increased formation of reactive oxygen species by an increase of dichlorofluorescein fluorescence, heat shock protein 70 was not upregulated in laser-treated cells. Additionally, no evidence of stress granule formation was visible by immunofluorescence staining. The data provided in this study help to identify the cellular reactions to gold nanoparticle–mediated laser manipulation. PMID:26562032

  11. Characterization of the cellular response triggered by gold nanoparticle-mediated laser manipulation

    NASA Astrophysics Data System (ADS)

    Kalies, Stefan; Keil, Sebastian; Sender, Sina; Hammer, Susanne C.; Antonopoulos, Georgios C.; Schomaker, Markus; Ripken, Tammo; Escobar, Hugo Murua; Meyer, Heiko; Heinemann, Dag

    2015-11-01

    Laser-based transfection techniques have proven high applicability in several cell biologic applications. The delivery of different molecules using these techniques has been extensively investigated. In particular, new high-throughput approaches such as gold nanoparticle-mediated laser transfection allow efficient delivery of antisense molecules or proteins into cells preserving high cell viabilities. However, the cellular response to the perforation procedure is not well understood. We herein analyzed the perforation kinetics of single cells during resonant gold nanoparticle-mediated laser manipulation with an 850-ps laser system at a wavelength of 532 nm. Inflow velocity of propidium iodide into manipulated cells reached a maximum within a few seconds. Experiments based on the inflow of FM4-64 indicated that the membrane remains permeable for a few minutes for small molecules. To further characterize the cellular response postmanipulation, we analyzed levels of oxidative heat or general stress. Although we observed an increased formation of reactive oxygen species by an increase of dichlorofluorescein fluorescence, heat shock protein 70 was not upregulated in laser-treated cells. Additionally, no evidence of stress granule formation was visible by immunofluorescence staining. The data provided in this study help to identify the cellular reactions to gold nanoparticle-mediated laser manipulation.

  12. Photo-triggering and secondary electron produced ionization in electric discharge ArF* excimer lasers

    NASA Astrophysics Data System (ADS)

    Xiong, Zhongmin; Kushner, Mark J.

    2011-10-01

    Electric discharge excimer lasers are sustained in multi-atmosphere attaching gas mixtures that are typically preionized to enable a reproducible, uniform glow, which maximizes optical quality and gain. This preionization is often accomplished using UV light produced by a corona discharge within the plasma cavity. To quantify the relationship between corona discharge properties and those of the laser discharge, the triggering of electron avalanche by preionizing UV light in an electric discharge-pumped ArF* excimer laser was numerically investigated using a two-dimensional model. The preionizing UV fluxes were generated by a corona-bar discharge driven by the same voltage pulse as the main discharge sustained in a multi-atmospheric Ne/Ar/Xe/F2 gas mixture. The resulting peak photo-electron density in the inter-electrode spacing is around 108 cm-3, and its distribution is biased toward the UV source. The preionization density increases with increasing dielectric constant and capacitance of the corona bar. The symmetry and uniformity of the discharge are, however, improved significantly once the main avalanche develops. In addition to bulk electron impact ionization, the ionization generated by sheath accelerated secondary electrons was found to be important in sustaining the discharge current at experimentally observed values. At peak current, the magnitude of the ionization by sheath accelerated electrons is comparable to that from bulk electron impact in the vicinity of the cathode.

  13. Movement of magnetic domain walls induced by single femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Sandig, O.; Shokr, Y. A.; Vogel, J.; Valencia, S.; Kronast, F.; Kuch, W.

    2016-08-01

    We present a microscopic investigation of how the magnetic domain structure in ultrathin films changes after direct excitation by single ultrashort laser pulses. Using photoelectron emission microscopy in combination with x-ray magnetic circular dichroism in the resonant absorption of soft x rays, we find that individual laser pulses of ≈60 fs duration and a central wavelength of 800 nm lead to clear changes in the domain structure of a Co layer of three atomic monolayers thickness in an epitaxial Co/Cu/Ni trilayer on a Cu(001) single-crystal substrate. A relatively small enhancement of the sample base temperature by 40 K is sufficient to lower the threshold of laser fluence for domain wall motion by about a factor of two. Pump-probe measurements with a laser fluence just below this threshold indicate that the laser-induced demagnetization of the sample is far from complete in these experiments. Although the domain wall motion appears similar to thermal domain wall fluctuations, quantitatively it cannot be explained by pure thermal activation of domain wall motion by the transient rise of sample temperature after the laser pulse, but it is likely to be triggered by a laser-induced depinning of domain walls.

  14. Investigating MALDI MSI parameters (Part 2) - On the use of a mechanically shuttered trigger system for improved laser energy stability.

    PubMed

    Steven, Rory T; Dexter, Alex; Bunch, Josephine

    2016-07-15

    Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) is now widely used to desorb, ionize and detect molecules from complex samples and tissue sections. The detected ion intensity within MALDI MS and MSI is intimately linked to the laser energy per pulse incident upon the sample during analysis. Laser energy/power stability can be significantly affected by the manner in which the laser is operated. High-repetition rate diode-pumped solid-state (DPSS) lasers are being increasingly adopted to enable high-throughput MALDI MSI analysis. Within this work two different laser-triggering setups are used to demonstrate the effect of laser energy instabilities due to spiking and thermal control phenomena and a setup with a shutter to remove these effects. The effect of non-equilibrium laser operation on MALDI MSI data versus the more stable laser pulse energy of the shutter-triggered system is demonstrated in thin films of α-cyano-4-hydroxycinnamic acid (CHCA) and for imaging of murine brain tissue sections. Significant unwanted variations in absolute and relative detected ion intensity are shown where energy variation is introduced by these phenomena, which return to equilibrium within the setup employed here over timescales relevant to MALDI MS analysis. PMID:27090002

  15. Live single-cell laser tag

    PubMed Central

    Binan, Loïc; Mazzaferri, Javier; Choquet, Karine; Lorenzo, Louis-Etienne; Wang, Yu Chang; Affar, El Bachir; De Koninck, Yves; Ragoussis, Jiannis; Kleinman, Claudia L.; Costantino, Santiago

    2016-01-01

    The ability to conduct image-based, non-invasive cell tagging, independent of genetic engineering, is key to cell biology applications. Here we introduce cell labelling via photobleaching (CLaP), a method that enables instant, specific tagging of individual cells based on a wide array of criteria such as shape, behaviour or positional information. CLaP uses laser illumination to crosslink biotin onto the plasma membrane, coupled with streptavidin conjugates to label individual cells for genomic, cell-tracking, flow cytometry or ultra-microscopy applications. We show that the incorporated mark is stable, non-toxic, retained for several days, and transferred by cell division but not to adjacent cells in culture. To demonstrate the potential of CLaP for genomic applications, we combine CLaP with microfluidics-based single-cell capture followed by transcriptome-wide next-generation sequencing. Finally, we show that CLaP can also be exploited for inducing transient cell adhesion to substrates for microengineering cultures with spatially patterned cell types. PMID:27198043

  16. Live single-cell laser tag.

    PubMed

    Binan, Loïc; Mazzaferri, Javier; Choquet, Karine; Lorenzo, Louis-Etienne; Wang, Yu Chang; Affar, El Bachir; De Koninck, Yves; Ragoussis, Jiannis; Kleinman, Claudia L; Costantino, Santiago

    2016-01-01

    The ability to conduct image-based, non-invasive cell tagging, independent of genetic engineering, is key to cell biology applications. Here we introduce cell labelling via photobleaching (CLaP), a method that enables instant, specific tagging of individual cells based on a wide array of criteria such as shape, behaviour or positional information. CLaP uses laser illumination to crosslink biotin onto the plasma membrane, coupled with streptavidin conjugates to label individual cells for genomic, cell-tracking, flow cytometry or ultra-microscopy applications. We show that the incorporated mark is stable, non-toxic, retained for several days, and transferred by cell division but not to adjacent cells in culture. To demonstrate the potential of CLaP for genomic applications, we combine CLaP with microfluidics-based single-cell capture followed by transcriptome-wide next-generation sequencing. Finally, we show that CLaP can also be exploited for inducing transient cell adhesion to substrates for microengineering cultures with spatially patterned cell types. PMID:27198043

  17. Injection seeded single mode alexandrite ring laser for lidar applications

    NASA Technical Reports Server (NTRS)

    Lee, H. Sang; Notari, Anthony

    1992-01-01

    Along with many spectroscopic applications, atmospheric lidar measurements require a tunable, narrow band laser with a very high degree of spectral purity. A standing wave pulsed alexandrite laser tuned by injection seeding with an AlGaAs laser diode has demonstrated high stability. The standing wave cavity, however, poses several difficulties in light of the single mode operation and efficient seeding beam into the cavity. In order to overcome these problems and to operate the high power alexandrite laser in a single axial mode with a high spectral purity, a new ring laser system is being developed. The design features of the ring laser and some measurements of the laser characteristics are presented.

  18. Laser triggered Z-pinch broadband extreme ultraviolet source for metrology

    SciTech Connect

    Tobin, I.; Lunney, J. G.; Juschkin, L.; Sidelnikov, Y.; O'Reilly, F.; Sokell, E.; Sheridan, P.

    2013-05-20

    We compare the extreme ultraviolet emission characteristics of tin and galinstan (atomic %: Ga: 78.35, In: 14.93, Sn: 6.72) between 10 nm and 18 nm in a laser-triggered discharge between liquid metal-coated electrodes. Over this wavelength range, the energy conversion efficiency for galinstan is approximately half that of tin, but the spectrum is less strongly peaked in the 13-15 nm region. The extreme ultraviolet source dimensions were 110 {+-} 25 {mu}m diameter and 500 {+-} 125 {mu}m length. The flatter spectrum, and -19 Degree-Sign C melting point, makes this galinstan discharge a relatively simple high radiance extreme ultraviolet light source for metrology and scientific applications.

  19. Two-color interferometer for the study of laser filamentation triggered electric discharges in air

    SciTech Connect

    Point, Guillaume Brelet, Yohann; Arantchouk, Leonid; Carbonnel, Jérôme; Prade, Bernard; Mysyrowicz, André; Houard, Aurélien

    2014-12-15

    We present a space and time resolved interferometric plasma diagnostic for use on plasmas where neutral-bound electron contribution to the refractive index cannot be neglected. By recording simultaneously the plasma optical index at 532 and 1064 nm, we are able to extract independently the neutral and free electron density profiles. We report a phase resolution of 30 mrad, corresponding to a maximum resolution on the order of 4×10{sup 22} m{sup −3} for the electron density, and of 10{sup 24} m{sup −3} for the neutral density. The interferometer is demonstrated on centimeter-scale sparks triggered by laser filamentation in air with typical currents of a few tens of A.

  20. Laser head for simultaneous optical pumping of several dye lasers. [with single flash lamp

    NASA Technical Reports Server (NTRS)

    Mumola, P. B.; Mcalexander, B. T. (Inventor)

    1975-01-01

    The invention is a laser head for simultaneous pumping several dye lasers with a single flash lamp. The laser head includes primarily a multi-elliptical cylinder cavity with a single flash lamp placed along the common focal axis of the cavity and with capillary tube dye cells placed along each of the other focal axes of the cavity. The inside surface of the cavity is polished. Hence, the single flash lamp supplies the energy to the several dye cells.

  1. Laser microirradiation of single nerve cell

    NASA Astrophysics Data System (ADS)

    Uzdensky, Anatoly B.

    1993-07-01

    Isolated crayfish mechanoreceptor neuron was microirradiated into its different region with various lasers (mainly with helium-cadmium laser, 441.6 nm). Laser microbeam was about 5 - 9 micrometers , intensity varied from 101 to 1.5(DOT)104 W/cm2, and wavelength--from 454 to 633 nm. Polyphasic neuron response on laser microirradiation (impulse frequency acceleration, then inhibition, new acceleration, and sudden irreversible impulsation ceasing) was described and its dependence on intensity, wavelength and localization was investigated. Complex electrophysiological, ultrastructural and cytochemical study along with results of neuron response modification with supravital stains, bioenergetic inhibitors, antioxidants gave evidences that impulsation acceleration phases were caused by laser effect on neuronal membrane, but inhibition phase--on mitochondria. Main intracellular laser radiation photoreceptors were probably flavins.

  2. Discretely tunable single-frequency fibre Bragg grating diode laser

    SciTech Connect

    Duraev, V P; Lutts, G B; Nedelin, E T; Sumarokov, M A; Medvedkov, O I; Vasil'ev, S A

    2007-12-31

    The results of the development of discretely tunable single-frequency semiconductor lasers with the external cavity based on fibre Bragg gratings (FBGs) written in a single-mode fibre are presented. It is shown, in particular, that, by using an external cavity semiconductor laser with the output mirror representing a superposition of several FBGs with different resonance wavelengths, it is possible to obtain lasing at one or several wavelengths simultaneously by varying the injection current and (or) the temperature of the active area of the laser diode. (lasers)

  3. Laser-initiated iodine radical chemistry in single microdroplets

    NASA Astrophysics Data System (ADS)

    Vaughn, Bartholomew S.; Tracey, Phillip J.; Trevitt, Adam J.

    2012-11-01

    Iodine radical reactions in single free-falling microdroplets of iodododecane, initiated using UV laser photolysis, are probed using Raman spectroscopy. Stimulated Raman spectra, with 532 nm laser excitation, are recorded at varying time delays from the UV pulse. I atom recombination reactions lead to I2 that changes the optical properties of the microdroplet ultimately quenching the Raman signal. This quenching is observed over ˜10 ns, which is about the time resolution of the two-laser experiment. Although the kinetics are too rapid to be measured in current laser configuration, it demonstrates that radical kinetics can be followed in single microdroplets.

  4. Interferometric and schlieren characterization of the plasmas and shock wave dynamics during laser-triggered discharge in atmospheric air

    SciTech Connect

    Wei, Wenfu; Li, Xingwen Wu, Jian; Yang, Zefeng; Jia, Shenli; Qiu, Aici

    2014-08-15

    This paper describes our efforts to reveal the underlying physics of laser-triggered discharges in atmospheric air using a Mach-Zehnder interferometer and schlieren photography. Unlike the hemispherical shock waves that are produced by laser ablation, bell-like morphologies are observed during laser-triggered discharges. Phase shifts are recovered from the interferograms at a time of 1000 ns by the 2D fast Fourier transform method, and then the values of the refractive index are deduced using the Abel inversion. An abundance of free electrons is expected near the cathode surface. The schlieren photographs visualize the formation of stagnation layers at ∼600 ns in the interaction zones of the laser- and discharge-produced plasmas. Multiple reflected waves are observed at later times with the development of shock wave propagations. Estimations using the Taylor-Sedov self-similar solution indicated that approximately 45.8% and 51.9% of the laser and electrical energies are transferred into the gas flow motions, respectively. Finally, numerical simulations were performed, which successfully reproduced the main features of the experimental observations, and provided valuable insights into the plasma and shock wave dynamics during the laser-triggered discharge.

  5. Feedback stabilization system for pulsed single longitudinal mode tunable lasers

    DOEpatents

    Esherick, Peter; Raymond, Thomas D.

    1991-10-01

    A feedback stabilization system for pulse single longitudinal mode tunable lasers having an excited laser medium contained within an adjustable length cavity and producing a laser beam through the use of an internal dispersive element, including detection of angular deviation in the output laser beam resulting from detuning between the cavity mode frequency and the passband of the internal dispersive element, and generating an error signal based thereon. The error signal can be integrated and amplified and then applied as a correcting signal to a piezoelectric transducer mounted on a mirror of the laser cavity for controlling the cavity length.

  6. Single-domain flavoenzymes trigger lytic polysaccharide monooxygenases for oxidative degradation of cellulose

    PubMed Central

    Garajova, Sona; Mathieu, Yann; Beccia, Maria Rosa; Bennati-Granier, Chloé; Biaso, Frédéric; Fanuel, Mathieu; Ropartz, David; Guigliarelli, Bruno; Record, Eric; Rogniaux, Hélène; Henrissat, Bernard; Berrin, Jean-Guy

    2016-01-01

    The enzymatic conversion of plant biomass has been recently revolutionized by the discovery of lytic polysaccharide monooxygenases (LPMOs) that carry out oxidative cleavage of polysaccharides. These very powerful enzymes are abundant in fungal saprotrophs. LPMOs require activation by electrons that can be provided by cellobiose dehydrogenases (CDHs), but as some fungi lack CDH-encoding genes, other recycling enzymes must exist. We investigated the ability of AA3_2 flavoenzymes secreted under lignocellulolytic conditions to trigger oxidative cellulose degradation by AA9 LPMOs. Among the flavoenzymes tested, we show that glucose dehydrogenase and aryl-alcohol quinone oxidoreductases are catalytically efficient electron donors for LPMOs. These single-domain flavoenzymes display redox potentials compatible with electron transfer between partners. Our findings extend the array of enzymes which regulate the oxidative degradation of cellulose by lignocellulolytic fungi. PMID:27312718

  7. Single-domain flavoenzymes trigger lytic polysaccharide monooxygenases for oxidative degradation of cellulose.

    PubMed

    Garajova, Sona; Mathieu, Yann; Beccia, Maria Rosa; Bennati-Granier, Chloé; Biaso, Frédéric; Fanuel, Mathieu; Ropartz, David; Guigliarelli, Bruno; Record, Eric; Rogniaux, Hélène; Henrissat, Bernard; Berrin, Jean-Guy

    2016-01-01

    The enzymatic conversion of plant biomass has been recently revolutionized by the discovery of lytic polysaccharide monooxygenases (LPMOs) that carry out oxidative cleavage of polysaccharides. These very powerful enzymes are abundant in fungal saprotrophs. LPMOs require activation by electrons that can be provided by cellobiose dehydrogenases (CDHs), but as some fungi lack CDH-encoding genes, other recycling enzymes must exist. We investigated the ability of AA3_2 flavoenzymes secreted under lignocellulolytic conditions to trigger oxidative cellulose degradation by AA9 LPMOs. Among the flavoenzymes tested, we show that glucose dehydrogenase and aryl-alcohol quinone oxidoreductases are catalytically efficient electron donors for LPMOs. These single-domain flavoenzymes display redox potentials compatible with electron transfer between partners. Our findings extend the array of enzymes which regulate the oxidative degradation of cellulose by lignocellulolytic fungi. PMID:27312718

  8. Self-seeded single-frequency laser peening method

    DOEpatents

    Dane, C. Brent; Hackel, Lloyd; Harris, Fritz B.

    2009-08-11

    A method of operating a laser to obtain an output pulse having a single wavelength, comprises inducing an intracavity loss into a laser resonator having an amount that prevents oscillation during a time that energy from the pump source is being stored in the gain medium. Gain is built up in the gain medium with energy from the pump source until formation of a single-frequency relaxation oscillation pulse in the resonator. Upon detection of the onset of the relaxation oscillation pulse, the intracavity loss is reduced, such as by Q-switching, so that the built-up gain stored in the gain medium is output from the resonator in the form of an output pulse at a single frequency. An electronically controllable output coupler is controlled to affect output pulse characteristics. The laser acts a master oscillator in a master oscillator power amplifier configuration. The laser is used for laser peening.

  9. Self-seeded single-frequency laser peening method

    DOEpatents

    DAne, C.Brent; Hackey, Lloyd A.; Harris, Fritz B.

    2012-06-26

    A method of operating a laser to obtain an output pulse having a single wavelength, comprises inducing an intracavity loss into a laser resonator having an amount that prevents oscillation during a time that energy from the pump source is being stored in the gain medium. Gain is built up in the gain medium with energy from the pump source until formation of a single-frequency relaxation oscillation pulse in the resonator. Upon detection of the onset of the relaxation oscillation pulse, the intracavity loss is reduced, such as by Q-switching, so that the built-up gain stored in the gain medium is output from the resonator in the form of an output pulse at a single frequency. An electronically controllable output coupler is controlled to affect output pulse characteristics. The laser acts a master oscillator in a master oscillator power amplifier configuration. The laser is used for laser peening.

  10. High-power single-frequency fiber lasers

    NASA Astrophysics Data System (ADS)

    Guan, Weihua

    Single frequency laser sources are desired in many applications. Various architectures for achieving high power single frequency fiber laser outputs have been investigated and demonstrated. Axial gain apodization can affect the lasing threshold and spectral modal discrimination of DFB lasers. Modeling results show that if properly tailored, the lasing threshold can be reduced by 21% without sacrificing modal discrimination, while simultaneously increasing the differential output power between both ends of the laser. A dual-frequency 2 cm silica fiber laser with a wavelength spacing of 0.3 nm was demonstrated using a polarization maintaining (PM) fiber Bragg grating (FBG) reflector. The output power reached 43 mW with the optical signal to noise ratio (OSNR) greater than 60 dB. By thermally tuning the overlap between the spectra of PM FBG and SM FBG, a single polarisation, single frequency fibre laser was also demonstrated with an output power of 35 mW. From the dual frequency fiber laser, dual frequency switching was achieved by tuning the pump power of the laser. The dual frequency switching was generated by the thermal effects of the absorbed pump in the ytterbium doped fiber. Suppression and elimination of self pulsing in a watt level, dual clad ytterbium doped fiber laser was demonstrated. Self pulsations are caused by the dynamic interaction between the photon population and the population inversion. The addition of a long section of passive fiber in the laser cavity makes the gain recovery faster than the self pulsation dynamics, allowing only stable continuous wave lasing. A single frequency, hybrid Brillouin/ytterbium fiber laser was demonstrated in a 12 m ring cavity The output power reached 40 mW with an OSNR greater than 50 dB. To scale up the output power, a dual clad hybrid Brillouin/ytterbium fiber laser was studied. A numerical model including third order SBS was used to calculate the laser power performance. Simulation shows that 5 W single

  11. Electromotive Triggering and Single Sweep Analysis of Vestibular Evoked Myogenic Potentials (VEMPs).

    PubMed

    Hecker, Dietmar J; Lohscheller, Joerg; Schorn, Bianca; Koch, Klaus Peter; Schick, Bernhard; Dlugaiczyk, Julia

    2014-01-01

    Cervical (c) and ocular (o) vestibular evoked myogenic potentials (VEMPs) provide important tools for measuring otolith function. However, two major drawbacks of this method are encountered in clinical practice. First, recording of oVEMPs is compromised by small n10 amplitudes. Second, VEMP analysis is currently based on the averaging technique, resulting in a loss of information compared to single sweep analysis. Here, we: 1) developed a novel electromotive trigger mechanism for evoking VEMPs by bone-conducted vibration to the forehead and 2) established maximum entropy extraction of complex wavelet transforms for calculation of phase synchronization between VEMP single sweeps. Both c- and oVEMPs were recorded for n=10 healthy individuals. The oVEMP n10 amplitude was consistently higher (right: 24.84±9.71 μV; left: 27.40±14.55 μV) than previously described. Stable VEMP signals were reached after a smaller number of head taps (oVEMPs 6; cVEMPs 11) compared to current recommendations. Phase synchronization vectors and phase shift values were successfully determined for simulated and clinically recorded VEMPs, providing information about the impact of noise and phase jitter on the VEMP signal. Thus, the proposed method constitutes an easy-to-use approach for the fast detection and analysis of VEMPs in clinical practice. PMID:23529108

  12. More About Laser Scanner Tests For Single-Event Upsets

    NASA Technical Reports Server (NTRS)

    Kim, Quiesup; Edmonds, Larry D.; Zoutendyk, John A.; Schwartz, Harvey R.

    1993-01-01

    Two reports describe preliminary theoretical and experimental studies based on method described in "Laser Scanner Tests For Single-Event Upsets" (NPO-18216). Laser-scan and heavy-ion data found correlated within factor of two. Method of testing for single-event upsets intended to overcome disadvantages of, complement, and/or substitute for more-expensive cyclotron-testing method, which does not provide spatial resolution.

  13. Development of a laser-induced breakdown spectroscopy instrument for detection and classification of single-particle aerosols in real-time

    NASA Astrophysics Data System (ADS)

    Tjärnhage, Torbjörn; Gradmark, Per-Åke; Larsson, Anders; Mohammed, Abdelsalam; Landström, Lars; Sagerfors, Eva; Jonsson, Per; Kullander, Fredrik; Andersson, Magnus

    2013-06-01

    Detection of aerosolized biological warfare agents by means of LIBS commonly operate with pulsed lasers running at constant repetition rate, resulting in very low hit rates. In this paper, we present a prototype where the LIBS laser is only fired if a particle is expected in the focal zone. A significantly improved hit rate for detection and classification of μm sized single particles in real-time is achieved. Hit rates of 40% and 70% for NaCl particles of sizes 3 and 7.0 μm, respectively, can be reached in triggered configuration, as compared to 1% and 2% when the laser is un-triggered.

  14. Ring laser having an output at a single frequency

    DOEpatents

    Hackell, Lloyd A.

    1991-01-01

    A ring laser is disclosed that produces a single frequency of laser radiation in either the pulsed mode of operation or the continuous waveform (cw) mode of operation. The laser comprises a ring laser in a bowtie configuration, a birefringent gain material such as Nd:YLF, an improved optical diode that supports laser oscillation having a desired direction of travel and linear polarization, and a Q-switch. An output coupler (mirror) having a high reflectivity, such as 94%, is disclosed. Also disclosed is a self-seeded method of operation in which the laser can provide a pulse or a series of pulses of high power laser radiation at a consistent single frequency with a high degree of amplitude stability and temporal stability. In operation, the laser is operated in continuous waveform (cw) at a low power output with the Q-switch introducing a loss into the resonating cavity. Pumping is continued at a high level, causing the gain material to store energy. When a pulse is desired, the Q-switch is actuated to substantially reduce the losses so that a pulse can build up based on the low level cw oscillation. The pulse quickly builds, using the stored energy in the gain medium to provide a high power output pulse. The process may be repeated to provide a series of high power pulses of a consistent single frequency.

  15. Despeckling fly's eye homogenizer for single mode laser diodes.

    PubMed

    Mizuyama, Yosuke; Harrison, Nathan; Leto, Riccardo

    2013-04-01

    A novel fly's eye homogenizer for single mode laser diodes is presented. This technology overcomes the speckle problem that has been unavoidable for fly's eye homogenizers used with coherent light sources such as single mode laser diodes. Temporal and spatial coherence are reduced simultaneously by introducing short pulse driving of the injection current and a staircase element. Speckle has been dramatically reduced to 5% from 87% compared to a conventional system and a uniform laser line illumination was obtained by the proposed fly's eye homogenizer with a single mode UV-blue laser diode for the first time. A new spatial coherence function was mathematically formulated to model the proposed system and was applied to a partially coherent intensity formula that was newly developed in this study from Wolf's theory to account for the results. PMID:23571997

  16. Laser ablation process for single-walled carbon nanotube production

    NASA Technical Reports Server (NTRS)

    Arepalli, Sivaram

    2004-01-01

    Different types of lasers are now routinely used to prepare single-walled carbon nanotubes. The original method developed by researchers at Rice University used a "double-pulse laser oven" process. Several researchers have used variations of the lasers to include one-laser pulse (green or infrared), different pulse widths (ns to micros as well as continuous wave), and different laser wavelengths (e.g., CO2, or free electron lasers in the near to far infrared). Some of these variations are tried with different combinations and concentrations of metal catalysts, buffer gases (e.g., helium), oven temperatures, flow conditions, and even different porosities of the graphite targets. This article is an attempt to cover all these variations and their relative merits. Possible growth mechanisms under these different conditions will also be discussed.

  17. Dependence of current rise time on laser-triggered discharge plasma

    NASA Astrophysics Data System (ADS)

    Lim, Soowon; Kamohara, Takashi; Hosseini, S. Hamid R.; Katsuki, Sunao

    2016-07-01

    A powerful, stable extreme ultraviolet (EUV) source is the most important component for EUV lithography and EUV mask inspection. Here, we investigate the characteristics of laser-triggered discharge plasma at three different current rise times, fast, middle and slow. A height-adjustable coaxial birdcage was used to change circuit inductance. The rise time was varied between 30 ns–55 ns with peak current of 10 kA. The time-integrated EUV (at 13.5 nm in 2% bandwidth) intensity for the fast rise time was found to be 55% stronger than that of the slow rise time despite its lower energy. A high-speed Mach–Zehnder interferogram and visible imaging of the pinch plasma were employed to discuss plasma compression processes qualitatively and quantitatively. Also discharge produced debris was investigated using a silicon-crystal witness plate. The fast rise current was found to have advantages such as lower debris, higher EUV intensity, and possibility of suppressing instability in comparison with the slow rise time. As expected, total debris amounts lessened proportionally to the primary charged energy, as found from a comparison of fast and slow rise currents.

  18. Laser-triggered hollow-cathode plasma process for film growth

    SciTech Connect

    Witanachchi, S.; Mahawela, P.; Mukherjee, P.

    2004-09-01

    A method of generating a pulsed plasma plume of metallic species using a hollow-cathode arc discharge arrangement is presented. Electrical energy from a pulse-forming network (PFN) generates the transient plasma that evaporates material from the anode that is placed inside a hollow cathode. The discharge is triggered by thermionic electrons produced by a CO{sub 2} laser pulse that impinges on one of the electrodes. This plasma process has been used to deposit carbon films in a low-pressure argon or nitrogen ambient. Current pulses of 4-10 ms in duration with peak currents of 350 A have been produced by the PFN. Characteristics of the produced plasma have been studied by optical emission spectroscopy. The amount of energy imparted to the argon plasma is more than that for a nitrogen plasma. Comparison of on-axis intensity for the 426.9 nm line of C{sup +} for the two plasmas shows that the density of carbon ions generated in the nitrogen plasma is higher than that in the argon plasma. Films deposited by this method have fairly uniform thickness profiles that are of the form cos{sup 0.4} {theta} for the argon plasma and cos{sup 2.2} {theta} for the nitrogen plasma. This indicates that the nitrogen plasma is more forward directed than the argon plasma. Deposition rates of about 10-16 A /pulse have been obtained for carbon films.

  19. Formation of nanowires via single particle-triggered linear polymerization of solid-state aromatic molecules.

    PubMed

    Horio, Akifumi; Sakurai, Tsuneaki; Lakshmi, G B V S; Kumar Avasthi, Devesh; Sugimoto, Masaki; Yamaki, Tetsuya; Seki, Shu

    2016-08-11

    Nanowires occupy a prestigious place in nanoelectronics, nanomechanics, and biomimetics. Although there are notable methods to grow nanowires via self-assembly, there is a key drawback in the need to find out the specific conditions appropriate for each system. In this sense, universal techniques to fabricate such nanowires from various organic materials have been sought for the continued progress of the related research field. Here we report one of the promising and facile methodologies to quantitatively produce nanowires with controlled geometrical parameters. In this method, referred to as "Single Particle-Triggered Linear Polymerization (STLiP)", organic thin films on a supporting substrate were irradiated with high-energy charged particles, accelerated by particle accelerators. Each particle penetrates from the top of the films to the substrate while gradually releasing kinetic energy along its trajectory (ion track), generating reactive intermediates such as radical species that eventually induce propagation reactions. The resulting polymerized products were integrated into nanowires with uniform diameter and length that can be isolated via development with appropriate organic solvents. Considering the widely applicable nature of STLiP to organic materials, the present technique opens a new door for access to a number of functional nanowires and their assembly. PMID:27355341

  20. A High Power Amplifier for a Single Mode 1064 Laser

    NASA Astrophysics Data System (ADS)

    Stites, R. W.; O'Hara, K. M.

    2011-05-01

    We report on the construction of a high power amplifier system for a single mode 1064 nm laser. At the heart of this device is a 0.27% neodymium doped yttrium orthovanadate crystal that is double end pumped by two 30 Watt broadband diode arrays at 808 nm. For a 50 Watt TEM00 single freqency seed laser, we have observed an amplified power output in excess of 60 Watts for single pass configuration. A further increase in output power can be attained by retroreflecting the beam back through the crystal a second time. Such a device has direct application in the construction of optical lattices where high power single frequency lasers are required.

  1. 337 nm matrix-assisted laser desorption/ionization of single aerosol particles.

    PubMed

    He, L; Murray, K K

    1999-09-01

    Matrix-assisted laser desorption/ionization (MALDI) mass spectra were obtained from single particles injected directly into a time-of-flight mass spectrometer. Aerosol particles were generated at atmospheric pressure using a piezoelectric single-particle generator or a pneumatic nebulizer and introduced into the mass spectrometer through a series of narrow-bore tubes. Particles were detected by light scattering that was used to trigger a 337 nm pulsed nitrogen laser and the ions produced by laser desorption were mass separated in a two-stage reflectron time-of-flight mass spectrometer. MALDI mass spectra of single particles containing bradykinin, angiotensin II, gramicidin S, vitamin B(12) or gramicidin D were obtained at mass resolutions greater than 400 FWHM. For the piezoelectric particle generator, the efficiency of particle delivery was estimated to be approximately 0.02%, and 50 pmol of sample were consumed for each mass spectrum. For the pneumatic nebulizer, mass spectra could be obtained from single particles containing less than 100 amol of analyte, although the sample consumption for a typical mass spectrum was over 400 pmol. PMID:10491586

  2. Single-mode properties of distributed-reflector lasers

    SciTech Connect

    Komori, K.; Arai, S.; Suematsu, Y.; Arima, Y.; Aoki, M.

    1989-06-01

    The fundamental properties of a distributed-reflector (DR) laser, consisting of an active section and a passive distributed reflector section are theoretically investigated. The DR laser, in principle, has the properties of high efficiency and high-power performance in dynamic-single-mode operation, thus eliminating the problems of low device efficiency in DFB lasers and low output power in DBR lasers. The effective length of a distributed reflector including gain and loss is introduced as a novel concept and is applied for the analytical determination of the lasing condition. The conditions required for dynamic-single-mode operation with one-facet output are given in terms of the propagation constant difference between the active and passive regions related to the coupling coefficient of the passive reflector. This condition is experimentally found to be attainable by utilizing a conventional fabrication process.

  3. Angular ion emission characteristics of a laser triggered tin vacuum arc as light source for extreme ultraviolet lithography

    NASA Astrophysics Data System (ADS)

    Verbraak, Harald; Küpper, Felix; Jonkers, Jeroen; Bergmann, Klaus

    2010-11-01

    The angular resolved emission of tin ions from a laser triggered vacuum arc to be used as light source for extreme ultraviolet lithography is presented. Ion energies of more than 200 keV for emission angles up to 50° with respect to the optical axis are observed. The angular emission characteristic is strongly anisotropic with a pronounced peak for fast ions into a cone with an opening angle of roughly 10° at an angle of 35° with respect to the optical axis. These ions also exhibit a distinct energy distribution function compared to the more isotropic emitted bulk of ions, which can be referred to different mechanisms of production. Looking at the discharge current parameters, the production of the directed fast ions can be connected with a peaked increase in the impedance, which gives hint to a plasma instability as origin of those ions. The emission of isotropic emitted ions is in agreement with a model of plasma expansion into vacuum. The emission characteristic is also strongly dependent on the parameter of the trigger laser. It is shown that using a double trigger laser pulse the fast ion production can be suppressed by more than one order of magnitude.

  4. Simple Laser-Ultrasonic System Using a Single-Frequency Pulsed Laser Oscillator

    NASA Astrophysics Data System (ADS)

    Blouin, A.; Carrion, L.; Padioleau, C.; Bouchard, P.; Monchalin, J.-P.

    2005-04-01

    We present a new pulsed laser oscillator and system for the optical detection of ultrasound in materials using a flashlamp-pumped dual Nd:YAG rod configuration. A single-frequency laser oscillator based on one rod inside a ring cavity is proposed. The second rod can be used as an amplifier for the oscillator or as a generation laser. Performance of the system is investigated with a two-wave mixing phase demodulator. Tests on metallic samples are presented.

  5. Single electron beam rf feedback free electron laser

    DOEpatents

    Brau, C.A.; Stein, W.E.; Rockwood, S.D.

    1981-02-11

    A free electron laser system and electron beam system for a free electron laser which uses rf feedback to enhance efficiency are described. Rf energy is extracted from a single electron beam by decelerating cavities and energy is returned to accelerating cavities using rf returns, such as rf waveguides, rf feedthroughs, resonant feedthroughs, etc. This rf energy is added to rf klystron energy to reduce the required input energy and thereby enhance energy efficiency of the system.

  6. Single shot cell irradiations with laser-driven protons

    SciTech Connect

    Humble, N.; Schmid, T. E.; Zlobinskaya, O.; Wilkens, J. J.; Allinger, K.; Hilz, P.; Ma, W.; Reinhardt, S.; Bin, J.; Kiefer, D.; Schreiber, J.; Drexler, G. A.; Friedl, A.

    2013-07-26

    Ion beams are relevant for radiobiological studies in basic research and for application in tumor therapy. Here we present a method to generate nanosecond proton bunches with single shot doses of up to 7 Gray by a tabletop high-power laser. Although in their infancy, laser-ion accelerators allow studying fast radiobiological processes at small-scale laboratories as exemplarily demonstrated by measurements of the relative biological effectiveness of protons in human tumor cells.

  7. Single shot cell irradiations with laser-driven protons

    NASA Astrophysics Data System (ADS)

    Humble, N.; Allinger, K.; Bin, J.; Drexler, G. A.; Friedl, A.; Hilz, P.; Kiefer, D.; Ma, W.; Reinhardt, S.; Schmid, T. E.; Zlobinskaya, O.; Schreiber, J.; Wilkens, J. J.

    2013-07-01

    Ion beams are relevant for radiobiological studies in basic research and for application in tumor therapy. Here we present a method to generate nanosecond proton bunches with single shot doses of up to 7 Gray by a tabletop high-power laser. Although in their infancy, laser-ion accelerators allow studying fast radiobiological processes at small-scale laboratories as exemplarily demonstrated by measurements of the relative biological effectiveness of protons in human tumor cells.

  8. Bidirectional current triggering in planar devices based on serially connected VO2 thin films using 965 nm laser diode.

    PubMed

    Kim, Jihoon; Park, Kyongsoo; Kim, Bong-Jun; Lee, Yong Wook

    2016-08-01

    By incorporating a 965 nm laser diode, the bidirectional current triggering of up to 30 mA was demonstrated in a two-terminal planar device based on serially connected vanadium dioxide (VO2) thin films grown by pulsed laser deposition. The bidirectional current triggering was realized by using the focused beams of laser pulses through the photo-thermally induced phase transition of VO2. The transient responses of laser-triggered currents were also investigated when laser pulses excited the device at a variety of pulse widths and repetition rates of up to 4.0 Hz. A switching contrast between off- and on-state currents was obtained as ~8333, and rising and falling times were measured as ~39 and ~29 ms, respectively, for 50 ms laser pulses. PMID:27505740

  9. Tunable Single-Frequency Near IR Lasers for DIAL Applications

    NASA Technical Reports Server (NTRS)

    Henderson, Sammy W.; Marquardt, John H.; Carrig, Timothy J.; Gatt, Phil; Smith, Duane D.; Hale, Charley P.

    2000-01-01

    Tunable single-frequency sources in the 2-4 micron wavelength region are useful for remote DIAL measurements of chemicals and pollutants. We are developing tunable single-frequency transmitters and receivers for both direct and coherent detection lidar measurement applications. We have demonstrated a direct-diode-pumped PPLN-based OPO that operates single frequency, produces greater than 10 mW cw and is tunable over the 2.5 - 3.9 micron wavelength region. This laser has been used to injection seed a pulsed PPLN OPO, pumped by a 1.064 micron Nd:YAG laser, producing 50-100 microJoule single-frequency pulses at 100 Hz PRF near 3.6 micron wavelength. In addition, we have demonstrated a cw Cr:ZnSe laser that is tunable over the 2.1 - 2.8 micron wavelength region. This laser is pumped by a cw diode-pumped Tm:YALO laser and has produced over 1.8 W cw. Tm- and Tm, Ho-doped single-frequency solid-state lasers that produce over 50 mW cw and are tunable over approximately 10 nm in the 2 -2.1 micron band with fast PZT tuning have also been demonstrated. A fast PZT-tunable Tm, Ho:YLF laser was used for a direct-detection column content DIAL measurement of atmospheric CO2. Modeling shows that that all these cw and pulsed sources are useful for column-content coherent DIAL measurements at several km range using topographic targets.

  10. Tunable ring laser using a tapered single mode fiber tip.

    PubMed

    Wang, Xiaozhen; Li, Yi; Bao, Xiaoyi

    2009-12-10

    A tunable ring laser using a tapered single mode fiber tip as a bandpass filter has been proposed and demonstrated for the first time to our knowledge. This is a simple and cost-effective tunable source. It is found that the tuning range and bandwidth of the laser are related to the relaxation time of the optical amplifier, the current of the amplifier, and the steepness of the tip shape. The calculations and experimental results show that the laser has a tuning range of 9 nm in the L-band and the spectral linewidth can be varied from 0.06 nm to 0.17 nm. PMID:20011024

  11. Coherence properties of a single-mode polariton laser

    NASA Astrophysics Data System (ADS)

    Kim, Seonghoon; Zhang, Bo; Wang, Zhaorong; Deng, Hui; Fischer, Julian; Brodbeck, Sebastian; Kamp, Martin; Schneider, Christian; Hofling, Sven; Univ of Michigan-Ann Arbor Collaboration; Univ of Wuerzberg Collaboration

    2016-05-01

    Exciton-polariton condensation is a promising low threshold coherent light source, namely a polariton laser. However, first- and second-order coherences of a polariton laser has been poor and not well understood in two dimensional microcavity systems. Here, we show experimentally that full second-order coherence is established in a single-mode polariton laser and maintained far above the lasing threshold. The coherence time of first-order coherence functions increases initially and then reduces as the number of polaritons in a ground state increases due to the polariton-polariton interaction. Moreover, a transition in spectral lineshape from Lorentzian to Gaussian was observed as the occupation number increases as a result of the large interaction energy. These results are in very good agreement with a single-mode atom laser theory. The single-mode polariton laser was realized by designing a subwavelength grating (SWG) mirror which provides strong lateral confinement for discrete polariton states and polarization-selective reflectance for lifted spin-degeneracy. The results would be important for making fully coherent polariton lasers, as well as nonlinear polariton devices.

  12. Improved operation of a microwave pulse compressor with a laser-triggered high-pressure gas plasma switch

    NASA Astrophysics Data System (ADS)

    Shlapakovski, A.; Gorev, S.; Krasik, Ya. E.

    2016-08-01

    The influence of laser beam parameters on the output pulses of a resonant microwave compressor with a laser-triggered plasma switch was investigated. The S-band compressor, consisting of a rectangular waveguide-based cavity and H-plane waveguide tee with a shorted side arm, was filled with pressurized dry air and pumped by 1.8-μs-long microwave pulses of up to 450 kW power. A Nd:YAG laser was used to ignite the gas discharge in the tee side arm for output pulse extraction. The laser beam (at 213 nm or 532 nm) was directed along the RF electric field lines. It was found that the compressor operated most effectively when the laser beam was focused at the center of the switch waveguide cross-section. In this case, the power extraction efficiency reached ˜47% at an output power of ˜14 MW, while when the laser beam was not focused the maximal extraction efficiency was only ˜20% at ˜6 MW output power. Focusing the laser beam resulted also in a dramatic decrease (down to <1 ns) in the delay of the output pulses' appearance with respect to the time of the beam's entrance into the switch, and the jitter of the output pulses' appearance was minimized. In addition, the quality of the output pulses' waveform was significantly improved.

  13. Single-shot diffusion measurement in laser-polarized Gas

    NASA Technical Reports Server (NTRS)

    Peled, S.; Tseng, C. H.; Sodickson, A. A.; Mair, R. W.; Walsworth, R. L.; Cory, D. G.

    1999-01-01

    A single-shot pulsed gradient stimulated echo sequence is introduced to address the challenges of diffusion measurements of laser polarized 3He and 129Xe gas. Laser polarization enhances the NMR sensitivity of these noble gases by >10(3), but creates an unstable, nonthermal polarization that is not readily renewable. A new method is presented which permits parallel acquisition of the several measurements required to determine a diffusive attenuation curve. The NMR characterization of a sample's diffusion behavior can be accomplished in a single measurement, using only a single polarization step. As a demonstration, the diffusion coefficient of a sample of laser-polarized 129Xe gas is measured via this method. Copyright 1999 Academic Press.

  14. Polyelectrolyte/carbon nanotube composite microcapsules and drug release triggered by laser irradiation

    NASA Astrophysics Data System (ADS)

    Saito, Haruyuki; Kato, Noritaka

    2016-03-01

    The fabrication of stimuli-responsive capsules is one of the hot topics in the research field of drug delivery systems. Near-infrared (NIR) light is one of the promising stimuli, because of its high transparency to biological tissues, and NIR-responsive capsules have been fabricated using various NIR-adsorbing materials. Here, we employed single-walled carbon nanotubes (SWCNTs) as the NIR-adsorbing material, and microcapsules containing SWCNTs were fabricated by a combination of the layer-by-layer and template-assisted methods. The anti-cancer drug was loaded into the capsules, and the release rates in the dark and under NIR laser irradiation were compared. Distinct release was confirmed in the latter case, whereas almost no release was detected in the former case, indicating that the SWCNT molecule is a suitable light absorber for use with optically addressable drug carriers.

  15. 6.1-MV, 0.79-MA laser-triggered gas switch for multimodule, multiterawatt pulsed-power accelerators

    NASA Astrophysics Data System (ADS)

    Lechien, K. R.; Stygar, W. A.; Savage, M. E.; Wakeland, P. E.; Anaya, V.; Artery, D. S.; Baremore, M. J.; Bliss, D. E.; Chavez, R.; Coombs, G. D.; Corley, J. P.; Jones, P. A.; Kipp, A. K.; Lewis, B. A.; Lott, J. A.; Lynch, J. J.; McKee, G. R.; Ploor, S. D.; Prestwich, K. R.; Roznowski, S. A.; Spencer, D. C.; White, S. D.; Woodworth, J. R.

    2010-03-01

    A 6.1-MV, 0.79-MA laser-triggered gas switch (LTGS) is used to synchronize the 36 modules of the Z machine at Sandia National Laboratories. Each module includes one switch, which serves as the last command-fired switch of the module, and hence is used to determine the time at which each module electrically closes relative to the other modules. The switch is ˜81-cm in length, ˜45-cm in diameter, and is immersed in mineral oil. The outer switch envelope consists of six corrugated monomer-cast acrylic insulators and five contoured stainless-steel rings. The trigger electrodes are fabricated from copper-infused tungsten. The switch is pressurized with several atmospheres of sulfur hexafluoride (SF6), which is turbulently purged within 2 seconds after every shot. Each switch is powered from a 6-MV, 0.78-MJ Marx generator which pulse charges a 24-nF intermediate-store water capacitor in 1.4-μs. Closure of the switch allows power to flow into pulse-forming transmission lines. The power pulse is subsequently compressed by water switches, which results in a total accelerator output power in excess of 70-TW. A previous version of the LTGS performed exceptionally at a 5.4-MV, 0.7-MA level on an engineering test module used for switch development. It exhibited a 1-σ jitter of ˜5ns, a prefire and flashover rate less than 0.1%, and a lifetime in excess of 150 shots. When installed on the Z accelerator, however, the switch exhibited a prefire probability of ˜3%, a flashover probability of ˜7%, and a 15-ns jitter. The difference in performance is attributed to several factors such as higher total charge transfer, exposure to more debris, and more stressful dynamic mechanical loading upon machine discharge. Under these conditions, the replacement lifetime was less than ten shots. Since refurbishment of Z in October 2007, there have been three LTGS design iterations to improve the performance at 6.1-MV. The most recent design exhibits a prefire rate of less than 0.1%, a

  16. 1540-nm single frequency single-mode pulsed all fiber laser for coherent Doppler lidar

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Diao, Weifeng; Liu, Yuan; Liu, Jiqiao; Hou, Xia; Chen, Weibiao

    2015-02-01

    A single-mode single frequency eye-safe pulsed all fiber laser based on master oscillator power amplification structure is presented. This laser is composed of a narrow linewidth distributed laser diode seed laser and two-stage cascade amplifiers. 0.8 m longitudinally gradient strained erbium/ytterbium co-doped polarization-maintaining fiber with a core diameter of 10 μm is used as the gain fiber and two acoustic-optics modulators are adopted to enhance pulse extinction ratio. A peak power of 160 W and a pulse width of 200 ns at 10 kHz repetition rate are achieved with transform-limited linewidth and diffraction-limited beam quality. This laser will be employed in a compact short range coherent Doppler wind lidar.

  17. Ultraviolet Laser-induced ignition of RDX single crystal

    NASA Astrophysics Data System (ADS)

    Yan, Zhonghua; Zhang, Chuanchao; Liu, Wei; Li, Jinshan; Huang, Ming; Wang, Xuming; Zhou, Guorui; Tan, Bisheng; Yang, Zongwei; Li, Zhijie; Li, Li; Yan, Hongwei; Yuan, Xiaodong; Zu, Xiaotao

    2016-02-01

    The RDX single crystals are ignited by ultraviolet laser (355 nm, 6.4 ns) pulses. The laser-induced damage morphology consisted of two distinct regions: a core region of layered fracture and a peripheral region of stripped material surrounding the core. As laser fluence increases, the area of the whole crack region increases all the way, while both the area and depth of the core region increase firstly, and then stay stable over the laser fluence of 12 J/cm2. The experimental details indicate the dynamics during laser ignition process. Plasma fireball of high temperature and pressure occurs firstly, followed by the micro-explosions on the (210) surface, and finally shock waves propagate through the materials to further strip materials outside and yield in-depth cracks in larger surrounding region. The plasma fireball evolves from isotropic to anisotropic under higher laser fluence resulting in the damage expansion only in lateral direction while maintaining the fixed depth. The primary insights into the interaction dynamics between laser and energetic materials can help developing the superior laser ignition technique.

  18. Ultraviolet Laser-induced ignition of RDX single crystal.

    PubMed

    Yan, Zhonghua; Zhang, Chuanchao; Liu, Wei; Li, Jinshan; Huang, Ming; Wang, Xuming; Zhou, Guorui; Tan, Bisheng; Yang, Zongwei; Li, Zhijie; Li, Li; Yan, Hongwei; Yuan, Xiaodong; Zu, Xiaotao

    2016-01-01

    The RDX single crystals are ignited by ultraviolet laser (355 nm, 6.4 ns) pulses. The laser-induced damage morphology consisted of two distinct regions: a core region of layered fracture and a peripheral region of stripped material surrounding the core. As laser fluence increases, the area of the whole crack region increases all the way, while both the area and depth of the core region increase firstly, and then stay stable over the laser fluence of 12 J/cm(2). The experimental details indicate the dynamics during laser ignition process. Plasma fireball of high temperature and pressure occurs firstly, followed by the micro-explosions on the (210) surface, and finally shock waves propagate through the materials to further strip materials outside and yield in-depth cracks in larger surrounding region. The plasma fireball evolves from isotropic to anisotropic under higher laser fluence resulting in the damage expansion only in lateral direction while maintaining the fixed depth. The primary insights into the interaction dynamics between laser and energetic materials can help developing the superior laser ignition technique. PMID:26847854

  19. Ultraviolet Laser-induced ignition of RDX single crystal

    PubMed Central

    Yan, Zhonghua; Zhang, Chuanchao; Liu, Wei; Li, Jinshan; Huang, Ming; Wang, Xuming; Zhou, Guorui; Tan, Bisheng; Yang, Zongwei; Li, Zhijie; Li, Li; Yan, Hongwei; Yuan, Xiaodong; Zu, Xiaotao

    2016-01-01

    The RDX single crystals are ignited by ultraviolet laser (355 nm, 6.4 ns) pulses. The laser-induced damage morphology consisted of two distinct regions: a core region of layered fracture and a peripheral region of stripped material surrounding the core. As laser fluence increases, the area of the whole crack region increases all the way, while both the area and depth of the core region increase firstly, and then stay stable over the laser fluence of 12 J/cm2. The experimental details indicate the dynamics during laser ignition process. Plasma fireball of high temperature and pressure occurs firstly, followed by the micro-explosions on the (210) surface, and finally shock waves propagate through the materials to further strip materials outside and yield in-depth cracks in larger surrounding region. The plasma fireball evolves from isotropic to anisotropic under higher laser fluence resulting in the damage expansion only in lateral direction while maintaining the fixed depth. The primary insights into the interaction dynamics between laser and energetic materials can help developing the superior laser ignition technique. PMID:26847854

  20. Transient Sub-Poissonian Distribution for Single-Mode Lasers

    NASA Technical Reports Server (NTRS)

    Zang, J. Y.; Gu, Q.; Tian, L. K.

    1996-01-01

    In this paper, the transient photon statistics for single-mode lasers is investigated by making use of the theory of quantum electrodynamics. By taking into account of the transitive time l,we obtain the master equation for Jaynes-Cummings model. The relation between the Mandel factor and the time is obtained by directly solving the master equation. The result shows that a transient phenomenon from the transient super-Poissonian distribution to the transient sub-Poissonian distribution occurs for single-mode lasers. In addition, the influences of the thermal light field and the cavity loss on the transient sub-Poissonian distribution are also studied.

  1. High efficiency single-mode-multimode-single-mode fiber laser with diffraction-limited beam output.

    PubMed

    Zhou, Jiaqi; He, Bing; Feng, Yan; Gu, Xijia

    2014-08-20

    We designed and tested an all-fiber, high efficiency Yb-doped laser operating at 1088 nm with a single-mode-multimode-single-mode (SMS) structure. A larger-mode-area gain fiber of 1.5 m length, with 20/130 μm core/cladding diameters was used to increase the absorption, and a diffraction-limited Gaussian output beam was obtained from the single-mode output fiber. Using a 976 nm laser diode as the pump source, the laser generated an output power up to 38.5 W with a slope efficiency of 70%. The output beam qualities, with and without SMS structure, were compared and showed that the fiber laser with the SMS structure can achieve high gain, short fiber length, and excellent beam quality. PMID:25321133

  2. Improving interaction in navigated surgery by combining a pan-tilt mounted laser and a pointer with triggering

    NASA Astrophysics Data System (ADS)

    Ojdanic, D.; Chen, L.; Peitgen, H.-O.

    2012-02-01

    User interaction during navigated surgery is often a critical issue in the overall procedure, as several complex aspects must be considered, such as sterility, workflow, field of view, and cognitive load. This work introduces a new approach for intraoperative interaction that seamlessly fits the high surgical requirements. A navigation system, typically consisting of a tracking system and a monitor for 3D virtual models, is augmented with a tracked pointer with triggering functionality and a pan-tilt mounted laser. The pointer, which is sterile and can be applied for landmark-based organ registration, is used for wireless interaction with the monitor scene. The laser system enables the calibration of the monitor, which is out of the tracking system's range. Moreover, the laser beam can focus on any organ point defined on the virtual model, which improves targeting or visual feedback during intervention. The calibration of the laser system, monitor, and triggered pointer is achieved by an effective procedure, which can be easily repeated in operating room. The mathematical background of the calibration is based on the Levenberg-Marquardt and Umeyama's algorithms.

  3. Single-Polarisation, Single-Frequency, 2 cm Ytterbium-Doped Fibre Laser

    SciTech Connect

    Guan, W.; Marciante, J.R.

    2007-05-23

    A single-polarisation, single-frequency, ytterbium-doped silica fibre laser has been demonstrated in a 2 cm linear cavity. The output power reaches 35 mW with an optical signal-to-noise ratio greater than 65 dB. A polarisation-maintaining fibre Bragg grating is used as the polarisation-dependent reflector to generate the single-polarisation output with the polarisation extinction ratio greater than 20 dB. The laser works stably for two hours under laboratory conditions.

  4. 250 W single-crystal fiber Yb:YAG laser.

    PubMed

    Délen, Xavier; Piehler, Stefan; Didierjean, Julien; Aubry, Nicolas; Voss, Andreas; Ahmed, Marwan Abdou; Graf, Thomas; Balembois, Francois; Georges, Patrick

    2012-07-15

    We demonstrate an Yb:YAG single-crystal fiber laser with 251 W output power in continuous-wave and an optical efficiency of 44%. This performance can be explained by the high overlap between pump and signal beams brought by the pump guiding and by the good thermal management provided by the single-crystal fiber geometry. The oscillator performance with a reflectivity of the output coupler as low as 20% also shows high potential for power amplification. PMID:22825171

  5. Single, composite, and ceramic Nd:YAG 946-nm lasers

    NASA Astrophysics Data System (ADS)

    Lan, Rui-Jun; Yang, Guang; Zheng-Ping, Wang

    2015-06-01

    Single, composite crystal and ceramic continuous wave (CW) 946-nm Nd:YAG lasers are demonstrated, respectively. The ceramic laser behaves better than the crystal laser. With 5-mm long ceramic, a CW output power of 1.46 W is generated with an optical conversion efficiency of 13.9%, while the slope efficiency is 17.9%. The optimal ceramic length for a 946-nm laser is also calculated. Project supported by the National Natural Science Foundation of China (Grant No. 61405171), the Natural Science Foundation of Shandong Province, China (Grant No. ZR2012FQ014), and the Science and Technology Program of the Shandong Higher Education Institutions of China (Grant No. J13LJ05).

  6. Laser-induced microbubble poration of localized single cells.

    PubMed

    Fan, Qihui; Hu, Wenqi; Ohta, Aaron T

    2014-05-01

    Laser-induced microbubbles were used to porate the cell membranes of localized single NIH/3T3 fibroblasts. Microsecond laser pulses were focused on an optically absorbent substrate, creating a vapour microbubble that oscillated in size at the laser focal point in a fluidic chamber. The shear stress accompanying the bubble size oscillation was able to porate nearby cells. Cell poration was demonstrated with the delivery of FITC-dextran dye with various molecular weights. Under optimal poration conditions, the cell poration efficiency was up to 95.2 ± 4.8%, while maintaining 97.6 ± 2.4% cell viability. The poration system is able to target a single cell without disturbing surrounding cells. PMID:24632785

  7. Laser Scanner Tests For Single-Event Upsets

    NASA Technical Reports Server (NTRS)

    Kim, Quiesup; Soli, George A.; Schwartz, Harvey R.

    1992-01-01

    Microelectronic advanced laser scanner (MEALS) is opto/electro/mechanical apparatus for nondestructive testing of integrated memory circuits, logic circuits, and other microelectronic devices. Multipurpose diagnostic system used to determine ultrafast time response, leakage, latchup, and electrical overstress. Used to simulate some of effects of heavy ions accelerated to high energies to determine susceptibility of digital device to single-event upsets.

  8. Separation of a single cell by red-laser manipulation

    NASA Astrophysics Data System (ADS)

    Shikano, Shuji; Horio, Koji; Ohtsuka, Yoshihiro; Eto, Yuzuro

    1999-10-01

    A single cell of yeast was separated from a bulk sample of yeast without causing damage to the cell. A focused red-laser light beam was used for trapping and transporting the cell. A specially designed microchannel separator played an essential role in the success of the separation.

  9. Single-frequency, single-polarization holmium-doped ZBLAN fiber laser

    NASA Astrophysics Data System (ADS)

    Zhu, X.; Zong, J.; Miller, A.; Wiersma, K.; Norwood, R. A.; Prasad, N. S.; Chavez-Pirson, A.; Peyghambarian, N.

    2013-02-01

    We present the performance of a single frequency, single-polarization holmium (Ho3+)-doped ZBLAN (ZrF4-BaF2-LaF3- AlF3-NaF) fiber laser at 1200 nm. This distributed Bragg reflector (DBR) fiber laser was developed by splicing a 22 mm long highly Ho3+-doped ZBLAN fiber to a pair of silica fiber Bragg gratings (FBG). The successful fusion splicing of silica fiber to ZBLAN fiber, with their very different melting temperatures, was accomplished by using NP Photonics proprietary splicing technique. The 3 mol% Ho3+-doped ZBLAN fiber had a core diameter of 6.5 μm and a cladding diameter of 125 μm. The threshold of this laser was seen to be about 260 mW, and when the pump power was 520 mW, the output power was about 10 mW. The efficiency of the 1200 nm single-frequency fiber laser, i.e. the ratio of the output power to the launched pump power, was about 3.8%. The linewidth of the 1200 nm single-frequency fiber laser was estimated to be about 100 kHz by comparing the measured frequency noise of the 1200 nm single-frequency fiber laser with that of 1 μm NP Photonics single-frequency fiber lasers whose linewidths have been measured to be in the 1- 10 kHz range. The relative intensity noise of this DBR all-fiber laser was measured to be < 110 dB/Hz at the relaxation oscillation peak and the polarization extinction ratio was measured to be > 19 dB. Due to its low phonon energy and long radiative lifetimes, rare-earth-doped ZBLAN allows various transitions that are typically terminated in silica glass, resulting in ultraviolet, visible, and infrared rare-earth doped ZBLAN lasers. Therefore, our results highlight the exciting prospect that the accessible wavelength range of single-frequency DBR fiber lasers can be expanded significantly by using rare-earth-doped ZBLAN fibers.

  10. Single photon laser altimeter data processing, analysis and experimental validation

    NASA Astrophysics Data System (ADS)

    Vacek, Michael; Peca, Marek; Michalek, Vojtech; Prochazka, Ivan

    2015-10-01

    Spaceborne laser altimeters are common instruments on-board the rendezvous spacecraft. This manuscript deals with the altimeters using a single photon approach, which belongs to the family of time-of-flight range measurements. Moreover, the single photon receiver part of the altimeter may be utilized as an Earth-to-spacecraft link enabling one-way ranging, time transfer and data transfer. The single photon altimeters evaluate actual altitude through the repetitive detections of single photons of the reflected laser pulses. We propose the single photon altimeter signal processing and data mining algorithm based on the Poisson statistic filter (histogram method) and the modified Kalman filter, providing all common altimetry products (altitude, slope, background photon flux and albedo). The Kalman filter is extended for the background noise filtering, the varying slope adaptation and the non-causal extension for an abrupt slope change. Moreover, the algorithm partially removes the major drawback of a single photon altitude reading, namely that the photon detection measurement statistics must be gathered. The developed algorithm deduces the actual altitude on the basis of a single photon detection; thus, being optimal in the sense that each detected signal photon carrying altitude information is tracked and no altitude information is lost. The algorithm was tested on the simulated datasets and partially cross-probed with the experimental data collected using the developed single photon altimeter breadboard based on the microchip laser with the pulse energy on the order of microjoule and the repetition rate of several kilohertz. We demonstrated that such an altimeter configuration may be utilized for landing or hovering a small body (asteroid, comet).

  11. Next generation 8xx nm laser bars and single emitters

    NASA Astrophysics Data System (ADS)

    Strauss, Uwe; Müller, Martin; Swietlik, Tomasz; Fehse, Robin; Lauer, Christian; Grönninger, Günther; König, Harald; Keidler, Markus; Fillardet, Thierry; Kohl, Andreas; Stoiber, Michael; Scholl, Iris; Biesenbach, Jens; Baeumler, Martina; Konstanzer, Helmer

    2011-03-01

    Semiconductor lasers with emission in the range 790 - 880 nm are in use for a variety of application resulting in different laser designs to fulfill requirements in output power, operation temperature and lifetimes. The output power is limited by self heating and catastrophic optical mirror damage at the laser facet (COMD). Now we present data on bars fabricated with our new facet technology, which enables us to double the maximum facet load. We present q-cw laser bar with 80% fill factor with increased power level to 350W in long term operation at 200μs and 100Hz. The COMD limit of the bar is as high as 680W. Using Quantel's optimized packaging stacks with 11 bars of 5mm widths are tested at up to 120A resulting over 66% power conversion efficiency at 1600W output power. Laser bars for continuous wave operation like 50% fill factor bars had an COMD limit of approx. 250W with conventional facet technology, the value is equivalent to 10W per 200μm emitter (conditions: 200μs). The new facet technology pushes the facet stability to 24W/emitter. The new process and an improved design enable us to shift continuous wave operation at 808nm from 100W to 150W/bar with lifetimes of several thousand hours at 30°C using DILAS mounting technology. Higher power is possible depending on lifetime requirements. The power conversion efficiency of the improved devices is as high as 62% at 200W cw. The next limitation of 8xxnm lasers is high temperature operation: Values of 60-80°C are common for consumer applications of single emitters. Therefore Osram developed a new epitaxial design which reduced the generation of bulk defects. The corresponding Osram single emitters operate at junction temperatures up to 95°C, a value which corresponds to 80°C heat sink temperature for lasers soldered on C-mount or 65°C case temperature for lasers mounted in TO can. Current densities of the single emitter broad area lasers are as high as 1.4kA/cm2 at 850nm emission wavelength.

  12. Laser to single-mode-fiber coupling: A laboratory guide

    NASA Technical Reports Server (NTRS)

    Ladany, I.

    1992-01-01

    All the information necessary to achieve reasonably efficient coupling of semiconductor lasers to single mode fibers is collected from the literature, reworked when necessary, and presented in a mostly tabular form. Formulas for determining the laser waist radius and the fiber mode radius are given. Imaging relations connecting these values with the object and image distances are given for three types of lenses: ball, hemisphere, and Gradient Index (GRIN). Sources for these lenses are indicated, and a brief discussion is given about ways of reducing feedback effects.

  13. Ultrasharp-front laser pulses generated by energetic-electron flux triggering of laser propagation in overdense plasmas

    NASA Astrophysics Data System (ADS)

    Li, Xiao-Ya; Yu, Yong; Shen, Bai-Fei; Wang, Jia-Xiang; Zhu, Wen-Jun; Chen, Zi-Yu; Ye, Yan

    2013-08-01

    This paper reports that an initially opaque plasma foil, irradiated by a laser pulse with intensity below the self-induced transparency (SIT) threshold, will become transparent, if a flux of energetic electrons is present. Based on this phenomenon, named flux-induced transparency (FIT), an approach to obtaining ultrasharp-front laser pulses is proposed. With the presence of an energetic-electron flux generated by a p-polarized laser irradiating an overdense plasma foil from the rear side, the propagation of an s-polarized laser irradiating the front surface of the foil can be manipulated. The transmitted s-polarized laser pulse has an ultrasharp front which rises by three orders of magnitude within a few laser cycles. The profile of the transmitted pulse is tunable by controlling the time at which the energetic-electron flux arrives at the front surface.

  14. Measurement of Raman spectra of single airborne absorbing particles trapped by a single laser beam.

    PubMed

    Ling, Lin; Li, Yong-qing

    2013-02-15

    We demonstrate a method for optical trapping and Raman spectroscopy of micron-sized, airborne absorbing particles using a single focused laser beam. A single Gaussian beam at 532 nm is used to trap and precisely manipulate absorbing airborne particles. The fluctuation of the position of the trapped particles is substantially reduced by controlling the power of the laser beam with a position-sensitive detector and a locking circuit. Raman spectra of the position-stabilized particles or clusters are then measured with an objective and CCD spectrograph. PMID:23455087

  15. Thrust Generating Mechanism of Nozzle Powered by Single Laser Pulse

    NASA Astrophysics Data System (ADS)

    Li, Qian; Hong, Yanji; She, Jinhu; Cao, Zhengrui; Wang, Junhua

    2006-05-01

    Using Sedov's strong explosion theory, the process of gas dynamics after air is broken down under the irradiation of single laser pulse is analyzed, and the analytic formulas of the fluid field parameters of the gas disturbed by shock wave inside the nozzle are educed. The theoretical values are validated by numerical simulation, and the thrust generating mechanism is disclosed. The result indicates that the thrust generated by the interaction of laser induced shock wave and nozzle is equal to the one generated by the reactive jet on nozzle exit during a period, but the trends of the thrust-time evolvement are different, which provides some available information for further study of the mechanism of air-breathing laser propulsion.

  16. Imaging Single ZnO Vertical Nanowire Laser Cavities using UV-Laser Scanning Confocal Microscopy

    SciTech Connect

    Gargas, D.J.; Toimil-Molares, M.E.; Yang, P.

    2008-11-17

    We report the fabrication and optical characterization of individual ZnO vertical nanowire laser cavities. Dilute nanowire arrays with interwire spacing>10 ?m were produced by a modified chemical vapor transport (CVT) method yielding an ideal platform for single nanowire imaging and spectroscopy. Lasing characteristics of a single vertical nanowire are presented, as well as high-resolution photoluminescence imaging by UV-laser scanning confocal microscopy. In addition, three-dimensional (3D) mapping of the photoluminescence emission performed in both planar and vertical dimensions demonstrates height-selective imaging useful for vertical nanowires and heteronanostructures emerging in the field of optoelectronics and nanophotonics.

  17. Development of Extreme Ultraviolet Radiation Source using Laser Triggered Vacuum Spark Discharge Plasma

    SciTech Connect

    Watanabe, Masato; Yamada, Junzaburo; Zhu Qiushi; Hotta, Eiki

    2009-01-21

    A laser triggerd discharge produced Sn plasma light source has been developed. Experimental parameters such as electrode separation and laser irradiation power are varied to optimize EUV emission power. It is clear that the maximum EUV radiation was occurred in the position where the pinch was observed.

  18. Research on synchronization of 15 parallel high gain photoconductive semiconductor switches triggered by high power pulse laser diodes

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Xia, Liansheng; Chen, Yi; Liu, Yi; Yang, Chao; Ye, Mao; Deng, Jianjun

    2015-01-01

    The synchronization of 15 parallel high gain gallium arsenide photoconductive semiconductor switches (GaAs PCSS) has been researched aiming to get higher output voltage. Each PCSS is triggered independently by a high power pulse laser diode. The pulse width, energy, peak power, and central wavelength of the laser pulse are approximately 18 ns, 360 μJ, 20 kW, and 905 nm, respectively. In the stacked Blumlein transmission lines structure, the synchronous conduction of 15 parallel GaAs PCSSs has been achieved by offering optimized bias voltage and laser parameters. The method of synchronization calculation is given, and the synchronization of the 15 parallel GaAs PCSSs is measured as 775 ps. Furthermore, influences of the bias voltage, laser parameters on the synchronization are analyzed. In the output terminal, superimposed by the output voltages of 15 Blumlein transmission lines, the total output voltage reaches up to 328 kV, which is the highest output voltage of GaAs PCSSs that has been reported so far.

  19. Single-mode operation of mushroom structure surface emitting lasers

    SciTech Connect

    Wang, Y.J.; Dziura, T.G.; Wang, S.C. ); Du, G.; Wang, S. )

    1991-01-01

    Mushroom structure vertical cavity surface emitting lasers with a 0.6 {mu}m GaAs active layer sandwiched by two Al{sub 0.6{sup {minus}}}Ga{sub 0.4}As-Al{sub 0.08}Ga{sub 0.92}As multilayers as top and bottom mirrors exhibit 15 mA pulsed threshold current at 880 nm. Single longitudinal and single transverse mode operation was achieved on lasers with a 5 {mu}m diameter active region at current levels near 2 {times} I{sub th}. The light output above threshold current was linearly polarized with a polarization ratio of 25:1.

  20. Stable multiwavelength single longitudinal mode dual ring Brillouin fiber laser

    NASA Astrophysics Data System (ADS)

    Liu, Yi; Yu, Jin-Long; Wang, Wen-Rui; Pan, Hong-Gang; Yang, En-Ze

    2015-04-01

    A novel stable multiwavelength single longitudinal mode (SLM) dual ring Brillouin fiber laser is proposed and demonstrated. Dual ring configuration with 100 and 10 m length of single mode fiber guarantees each Stokes and anti-Stokes waves in SLM status. Linewidth of the first Stokes wave is below 4 kHz with 60 dB sidemode suppression value. 7 stable SLM lasing wavelengths including the pump with a 5 dB bandwidth of 0.5, 0.084 nm wavelength spacing and 15 dB average optical signal-to-noise ratio are generated through the cascaded SBS and degenerate FWM process. The laser can freely be tuned 30 nm range from 1535 to 1565 nm. The power fluctuation of the first Stokes wave is about 8 % measured by Data Acquisition System in 1 h.

  1. Passively mode-locked single-polarization microstructure fiber laser.

    PubMed

    Ortaç, B; Lecaplain, C; Hideur, A; Schreiber, T; Limpert, J; Tünnermann, A

    2008-02-01

    The generation of high-power and stable ultra-short pulses from a passively mode-locked purely normal dispersion fiber laser is reported using the unique combination of a photonic crystal fiber featuring single-polarization, single-mode, and low nonlinearity with a high modulation depth semiconductor saturable absorber mirror. The environmentally-stable, self-starting fiber laser generates 1.6 W of average power at a repetition rate of 63 MHz, corresponding to a pulse energy of 25 nJ. The emitted pulses are positively chirped with a pulse duration of 3.7 ps. They are compressible down to a near transform-limited duration of 750 fs. Numerical simulations are in good agreement with the experimental results. PMID:18542292

  2. Optofluidic lasers with a single molecular layer of gain

    PubMed Central

    Chen, Qiushu; Ritt, Michael; Sivaramakrishnan, Sivaraj; Sun, Yuze; Fan, Xudong

    2014-01-01

    We achieve optofluidic lasers with a single molecular layer of gain, in which green fluorescent protein, dye-labeled bovine serum albumin, and dye-labeled DNA are respectively used as the gain medium and attached to the surface of a ring resonator via surface immobilization biochemical methods. It is estimated that the surface density of the gain molecules is on the order of 1012/cm2, sufficient for lasing under pulsed optical excitation. It is further shown that the optofluidic laser can be tuned by energy transfer mechanisms through biomolecular interactions. This work not only opens a door to novel photonic devices that can be controlled at the level of a single molecular layer, but also provides a promising sensing platform to analyze biochemical processes at the solid-liquid interface. PMID:25312306

  3. Mode Selection for a Single-Frequency Fiber Laser

    NASA Technical Reports Server (NTRS)

    Liu, Jian

    2010-01-01

    A superstructured fiber-grating-based mode selection filter for a single-frequency fiber laser eliminates all free-space components, and makes the laser truly all-fiber. A ring cavity provides for stable operations in both frequency and power. There is no alignment or realignment required. After the fibers and components are spliced together and packaged, there is no need for specially trained technicians for operation or maintenance. It can be integrated with other modules, such as telescope systems, without extra optical alignment due to the flexibility of the optical fiber. The filter features a narrow line width of 1 kHz and side mode suppression ratio of 65 dB. It provides a high-quality laser for lidar in terms of coherence length and signal-to-noise ratio, which is 20 dB higher than solid-state or microchip lasers. This concept is useful in material processing, medical equipment, biomedical instrumentation, and optical communications. The pulse-shaping fiber laser can be directly used in space, airborne, and satellite applications including lidar, remote sensing, illuminators, and phase-array antenna systems.

  4. A single comb laser source for short reach WDM interconnects

    NASA Astrophysics Data System (ADS)

    Wojcik, Gregory L.; Yin, Dongliang; Kovsh, Alexey R.; Gubenko, Alexey E.; Krestnikov, Igor L.; Mikhrin, Sergey S.; Livshits, Daniil A.; Fattal, David A.; Fiorentino, Marco; Beausoleil, Raymond G.

    2009-02-01

    High-channel-count WDM will eventually be used for short reach optical interconnects since it maximizes link bandwidth and efficiency. An impediment to adoption is the fact that each WDM wavelength currently requires its own DFB laser. The alternative is a single, multi-wavelength laser, but noise, size and/or expense make existing options impractical. In contrast, a new low-noise, diode comb laser based on InAs/GaAs quantum dots provides a practical and timely alternative, albeit in the O-band. Samples are being evaluated in short reach WDM development systems. Tests show this type of Fabry-Perot laser permits >10 Gb/s error-free modulation of 10 to over 50 separate channels, as well as potential for 1.25 Gb/s direct modulation. The paper describes comb laser requirements, noise measurements for external and direct modulation, O-band issues, transmitter photonic circuitry and components, future CMP applications, and optical couplers that may help drive down packaging costs to below a dollar.

  5. Holograms for laser diode: Single mode optical fiber coupling

    NASA Technical Reports Server (NTRS)

    Fuhr, P. L.

    1982-01-01

    The low coupling efficiency of semiconductor laser emissions into a single mode optical fibers place a severe restriction on their use. Associated with these conventional optical coupling techniques are stringent alignment sensitivities. Using holographic elements, the coupling efficiency may be increased and the alignment sensitivity greatly reduced. Both conventional and computer methods used in the generation of the holographic couplers are described and diagrammed. The reconstruction geometries used are shown to be somewhat restrictive but substantially less rigid than their conventional optical counterparts. Single and double hologram techniques are examined concerning their respective ease of fabrication and relative merits.

  6. Laser direct micro-machining with top-hat-converted single mode lasers

    NASA Astrophysics Data System (ADS)

    Homburg, O.; Toennissen, F.; Mitra, T.; Lissotschenko, V.

    2008-02-01

    Laser direct micro-machining processes are used in a variety of industries like inkjet printing, semiconductor processing, solar technology, flat-panel display production and medicine. Various kinds of materials, e.g. ceramics, metals, isolators, oxides, organics and semiconductors are being structured. In most cases pulsed single mode solid state lasers with an inhomogeneous Gaussian beam profile are employed, like YAG lasers and their harmonics. However, the quality and functionality of the generated structures and micro-systems as well as the speed of the process can be improved by the utilization of homogeneous top hat profiles. The beam shaping principle of refractive Gaussian-to-top-hat converters is shown. Compact beam shaper modules based on this principle have been developed - supporting most direct laser micro-machining applications. The resulting process advantages are demonstrated by selected application results, namely the drilling of holes and patterning of trenches for different kinds of materials.

  7. Photothermic regulation of gene expression triggered by laser-induced carbon nanohorns

    PubMed Central

    Miyako, Eijiro; Deguchi, Tomonori; Nakajima, Yoshihiro; Yudasaka, Masako; Hagihara, Yoshihisa; Horie, Masanori; Shichiri, Mototada; Higuchi, Yuriko; Yamashita, Fumiyoshi; Hashida, Mitsuru; Shigeri, Yasushi; Yoshida, Yasukazu; Iijima, Sumio

    2012-01-01

    The development of optical methods to control cellular functions is important for various biological applications. In particular, heat shock promoter-mediated gene expression systems by laser light are attractive targets for controlling cellular functions. However, previous approaches have considerable technical limitations related to their use of UV, short-wavelength visible (vis), and infrared (IR) laser light, which have poor penetration into biological tissue. Biological tissue is relatively transparent to light inside the diagnostic window at wavelengths of 650–1,100 nm. Here we present a unique optical biotechnological method using carbon nanohorn (CNH) that transforms energy from diagnostic window laser light to heat to control the expression of various genes. We report that with this method, laser irradiation within the diagnostic window resulted in effective heat generation and thus caused heat shock promoter-mediated gene expression. This study provides an important step forward in the development of light-manipulated gene expression technologies. PMID:22529368

  8. Efficient femtosecond Yb:YAG laser pumped by a single-mode laser diode

    NASA Astrophysics Data System (ADS)

    Agnesi, Antonio; Greborio, Alessandro; Pirzio, Federico; Reali, Giancarlo

    2011-08-01

    Single-mode diodes enable a particularly simple, compact and effective pumping of solid-state laser devices for many specialized applications. We investigated a single-mode, 300-mW laser diode for pumping at 935 nm a Yb:YAG laser passively mode-locked by a semiconductor saturable absorber. Relatively short pulse generation (156 fs), tunable across 1033-1059 nm has been demonstrated. An optical-to-optical efficiency of about 28% has been obtained with 320 fs long pulses. Therefore, contrarily to what previously believed, compact diode-pumped ultrafast Yb:YAG oscillators can reliably and efficiently deliver pulses in the range of ≈ 100-200 fs with few tens of mW, which are very appealing for bio-diagnostics and amplifier seeding applications.

  9. Full-Duplex Digital Communication on a Single Laser Beam

    NASA Technical Reports Server (NTRS)

    Hazzard, D. A.; MacCannell, J. A.; Lee, G.; Selves, E. R.; Moore, D.; Payne, J. A.; Garrett, C. D.; Dahlstrom, N.; Shay, T. M.

    2006-01-01

    A proposed free-space optical communication system would operate in a full-duplex mode, using a single constant-power laser beam for transmission and reception of binary signals at both ends of the free-space optical path. The system was conceived for two-way data communication between a ground station and a spacecraft in a low orbit around the Earth. It has been estimated that in this application, a data rate of 10 kb/s could be achieved at a ground-station-to-spacecraft distance of 320 km, using a laser power of only 100 mW. The basic system concept is also applicable to terrestrial free-space optical communications. The system (see figure) would include a diode laser at one end of the link (originally, the ground station) and a liquid-crystal- based retroreflecting modulator at the other end of the link (originally, the spacecraft). At the laser end, the beam to be transmitted would be made to pass through a quarter-wave plate, which would convert its linear polarization to right circular polarization. For transmission of data from the laser end to the retroreflector end, the laser beam would be modulated with subcarrier phase-shift keying (SC-PSK). The transmitted beam would then pass through an aperture- sharing element (ASE) - basically, a mirror with a hole in it, used to separate the paths of the transmitted and received light beams. The transmitted beam would continue outward through a telescope (which, in the original application, would be equipped with a spacecraft-tracking system) that would launch the transmitted beam along the free-space optical path to the retroreflector end.

  10. High-frequency trigger generators for CuBr-laser high voltage pumping source

    NASA Astrophysics Data System (ADS)

    Torgaev, S.; Kozhemyak, O.; Yaroslavtsev, E.; Trigub, M.; Musorov, I.; Chertikhina, D.

    2016-04-01

    In this paper the circuits of high frequency trigger generators of pulses of the nanosecond duration are presented. A detailed study of a generator based on the avalanche transistor with the use of a coaxial cable instead of a capacitor is described. This circuit showed advanced characteristics of the output pulses. A circuit of a generator built on high-speed digital components is also considered. The basic advantages and disadvantages of both generators are presented in this paper.

  11. Single crystals popping under UV light: a photosalient effect triggered by a [2+2] cycloaddition reaction.

    PubMed

    Medishetty, Raghavender; Husain, Ahmad; Bai, Zhaozhi; Runčevski, Tomče; Dinnebier, Robert E; Naumov, Panče; Vittal, Jagadese J

    2014-06-01

    The extremely rare examples of dynamic single crystals where excitation by light or heat induces macroscopic motility present not only a visually appealing demonstration of the utility of molecular materials for conversion of energy to work, but they also provide a unique opportunity to explore the mechanistic link between collective molecular processes and their consequences at a macroscopic level. Here, we report the first example of a photosalient effect (photoinduced leaping) observed with crystals of three coordination complexes which is induced by a [2+2] photocycloaddition reaction. Unlike a plethora of other dimerization reactions, when exposed to even weak UV light, single crystals of these materials burst violently, whereby they are propelled to travel several millimeters. The results point to a multistep mechanism where the strain energy that has been accumulated during the dimerization triggers a rapid structure transformation which ultimately results in crystal disintegration. PMID:24664890

  12. Velocity measurements by laser resonance fluorescence. [single atom diffusional motion

    NASA Technical Reports Server (NTRS)

    She, C. Y.; Fairbank, W. M., Jr.

    1980-01-01

    The photonburst correlation method was used to detect single atoms in a buffer gas. Real time flow velocity measurements with laser induced resonance fluorescence from single or multiple atoms was demonstrated and this method was investigated as a tool for wind tunnel flow measurement. Investigations show that single atoms and their real time diffusional motion on a buffer gas can be measured by resonance fluorescence. By averaging over many atoms, flow velocities up to 88 m/s were measured in a time of 0.5 sec. It is expected that higher flow speeds can be measured and that the measurement time can be reduced by a factor of 10 or more by careful experimental design. The method is clearly not ready for incorporation in high speed wind tunnels because it is not yet known whether the stray light level will be higher or lower, and it is not known what detection efficiency can be obtained in a wind tunnel situation.

  13. Tunable single-mode slot waveguide quantum cascade lasers

    SciTech Connect

    Meng, Bo; Tao, Jin; Quan Zeng, Yong; Wu, Sheng; Jie Wang, Qi

    2014-05-19

    We report experimental demonstration of tunable, monolithic, single-mode quantum cascade lasers (QCLs) at ∼10 μm with a two-section etched slot structure. A single-mode tuning range of 77 cm{sup −1} (785 nm), corresponding to ∼7.8% of the relative tuning range, was realized with a ∼20 dB side mode suppression ratio within the whole tuning range. Compared with integrated distributed feedback QCLs, our devices have the advantages of easy fabrication and a broader tuning range. Further theoretical analyses and numerical simulations show that it is possible to achieve a broad continuous tuning range by optimizing the slot structures. The proposed slot-waveguide design could provide an alternative but simple approach to the existing tuning schemes for realizing broadly continuous tunable single-mode QCLs.

  14. Single-Frequency Narrow Linewidth 2 Micron Fiber Laser

    NASA Technical Reports Server (NTRS)

    Jiang, Shibin (Inventor); Spiegelberg, Christine (Inventor); Luo, Tao (Inventor)

    2006-01-01

    A compact single frequency, single-mode 2 .mu.m fiber laser with narrow linewidth, <100 kHz and preferably <100 kHz, is formed with a low phonon energy glass doped with triply ionized rare-earth thulium and/or holmium oxide and fiber gratings formed in sections of passive silica fiber and fused thereto. Formation of the gratings in passive silica fiber both facilitates splicing to other optical components and reduces noise thus improving linewidth. An increased doping concentration of 0.5 to 15 wt. % for thulium, holmium or mixtures thereof produces adequate gain, hence output power levels for fiber lengths less than 5 cm and preferably less than 3 cm to enable single-frequency operation.

  15. Multiple Isotope Magneto Optical Trap from a single diode laser

    NASA Astrophysics Data System (ADS)

    Gomez, Eduardo; Valenzuela, Victor; Hamzeloui, Saeed; Gutierrez, Monica

    2013-05-01

    We present a simple design for a Dual Isotope Magneto Optical Trap. The system requires a single diode laser, a fiber modulator and a tapered amplifier to trap and completely control both 85Rb and 87Rb. We generate all the frequencies needed for trapping both species using the fiber intensity modulator. All the frequencies are amplified simultaneously with the tapered amplifier. The position and power of each frequency is now controlled independently on the RF rather than on the optical side. This introduces an enormous simplification for laser cooling that often requires an acousto-optic modulator for each frequency. The range of frequency changes is much bigger than what is available with acousto-optic modulators since in our case is determined by the modulator bandwidth (10 GHz). Additional isotopes can be simply added by including additional RF frequencies to the modulator and extra beams for other uses can be produced the same way. Support from CONACYT, PROMEP and UASLP.

  16. Parametric four-wave mixing using a single cw laser.

    PubMed

    Brekke, E; Alderson, L

    2013-06-15

    Four-wave mixing can be used to generate coherent output beams, with frequencies difficult to acquire in commercial lasers. Here, a single narrow external cavity diode laser locked to the two photon 5s-5d transition in rubidium is combined with a tapered amplifier system to produce a high power cw beam at 778 nm and used to generate coherent light at 420 nm through parametric four-wave mixing. This process is analyzed in terms of the intensity and frequency of the incoming beam as well as the atomic density of the sample. The efficiency of the process is currently limited when on resonance due to the absorption of the 420 nm beam, and modifications should allow a significant increase in output power. PMID:23939005

  17. Optical diagnostics of vascular reactions triggered by weak allergens using laser speckle-contrast imaging technique

    SciTech Connect

    Kuznetsov, Yu L; Kalchenko, V V; Astaf'eva, N G; Meglinski, I V

    2014-08-31

    The capability of using the laser speckle contrast imaging technique with a long exposure time for visualisation of primary acute skin vascular reactions caused by a topical application of a weak contact allergen is considered. The method is shown to provide efficient and accurate detection of irritant-induced primary acute vascular reactions of skin. The presented technique possesses a high potential in everyday diagnostic practice, preclinical studies, as well as in the prognosis of skin reactions to the interaction with potentially allergenic materials. (laser biophotonics)

  18. Single photon triggered dianion formation in TCNQ and F4TCNQ crystals

    PubMed Central

    Ma, Lin; Hu, Peng; Jiang, Hui; Kloc, Christian; Sun, Handong; Soci, Cesare; Voityuk, Alexander A.; Michel-Beyerle, Maria E.; Gurzadyan, Gagik G.

    2016-01-01

    Excited state dynamics in two strong organic electron acceptor systems, TCNQ and F4TCNQ single crystals, was studied. After absorption of a single photon, dianions are formed in both crystals on ultrashort timescale: TCNQ τ < 50 fs, F4TCNQ τ = 4 ps. By use of transient absorption spectroscopy, we demonstrate that the dianion formation in F4TCNQ is mediated by the radical anion precursor which is described by a two-step model. Our measurements show the phenomenon that in this quinoid acceptor crystals in the absence of additional donor molecule, it is possible to resolve the two step formation of a doubly charged anion upon absorption of a single low energy photon (2.6 eV). PMID:27346797

  19. Robust single trial identification of conscious percepts triggered by sensory events of variable saliency.

    PubMed

    Teixeira, Marta; Pires, Gabriel; Raimundo, Miguel; Nascimento, Sérgio; Almeida, Vasco; Castelo-Branco, Miguel

    2014-01-01

    The neural correlates of visual awareness are elusive because of its fleeting nature. Here we have addressed this issue by using single trial statistical "brain reading" of neurophysiological event related (ERP) signatures of conscious perception of visual attributes with different levels of saliency. Behavioral reports were taken at every trial in 4 experiments addressing conscious access to color, luminance, and local phase offset cues. We found that single trial neurophysiological signatures of target presence can be observed around 300 ms at central parietal sites. Such signatures are significantly related with conscious perception, and their probability is related to sensory saliency levels. These findings identify a general neural correlate of conscious perception at the single trial level, since conscious perception can be decoded as such independently of stimulus salience and fluctuations of threshold levels. This approach can be generalized to successfully detect target presence in other individuals. PMID:24465957

  20. The triggering of steam explosions of single drops of pure and alloyed molten aluminum

    SciTech Connect

    Nelson, L.S.; Fuketa, T.; Eatough, M.J.; Vigil, F.J. )

    1990-06-01

    When a hot liquid (fuel) comes into contact with a cold liquid (coolant), a variety of different fuel/coolant interactions (FCIs) can occur. For certain research on production reactors, the coolant of interest is water (either H{sub 2}O or D{sub 2}O), while the fuel is a molten alloy based mainly on aluminum and uranium. Aluminum-based melts have been shown to be explosive in many experiments performed by the aluminum industry and in several reactor experiments and accidents including NRX, SPERT, BORAX, etc. In the aluminum industry, steam explosions continue to result in property damage, personal injuries, and deaths. It is also known that certain alloying components, notably lithium, can enhance the strength of the explosions as well as the probability of their occurrence. To obtain quantitative information relating to the FCIs that might occur with uranium-aluminum fuel, a laboratory-scale experimental scoping study was begun at Sandia National Laboratories. The overall objective of this research program is to provide an understanding of the mechanism of steam explosions with the melt compositions expected in various hypothetical core meltdown accident scenarios in production reactors. In this program, it has been demonstrated that reproducible triggering of steam explosions with pure and alloyed aluminum can be achieved with both focused and unfocused shock waves generated with underwater electrical discharges.

  1. A single homeobox gene triggers phase transition, embryogenesis and asexual reproduction.

    PubMed

    Horst, Nelly A; Katz, Aviva; Pereman, Idan; Decker, Eva L; Ohad, Nir; Reski, Ralf

    2016-01-01

    Plants characteristically alternate between haploid gametophytic and diploid sporophytic stages. Meiosis and fertilization respectively initiate these two different ontogenies(1). Genes triggering ectopic embryo development on vegetative sporophytic tissues are well described(2,3); however, a genetic control of embryo development from gametophytic tissues remains elusive. Here, in the moss Physcomitrella patens we show that ectopic overexpression of the homeobox gene BELL1 induces embryo formation and subsequently reproductive diploid sporophytes from specific gametophytic cells without fertilization. In line with this, BELL1 loss-of-function mutants have a wild-type phenotype, except that their egg cells are bigger and unable to form embryos. Our results identify BELL1 as a master regulator for the gametophyte-to-sporophyte transition in P. patens and provide mechanistic insights into the evolution of embryos that can generate multicellular diploid sporophytes. This developmental innovation facilitated the colonization of land by plants about 500 million years ago(4) and thus shaped our current ecosystems. PMID:27250874

  2. Triggered Jovian radio emissions

    NASA Technical Reports Server (NTRS)

    Calvert, W.

    1985-01-01

    Certain Jovian radio emissions seem to be triggered from outside, by much weaker radio waves from the sun. Recently found in the Voyager observations near Jupiter, such triggering occurs at hectometric wavelengths during the arrival of solar radio bursts, with the triggered emissions lasting sometimes more than an hour as they slowly drifted toward higher frequencies. Like the previous discovery of similar triggered emissions at the earth, this suggests that Jupiter's emissions might also originate from natural radio lasers.

  3. Shock wave interaction with laser-generated single bubbles.

    PubMed

    Sankin, G N; Simmons, W N; Zhu, S L; Zhong, P

    2005-07-15

    The interaction of a lithotripter shock wave (LSW) with laser-generated single vapor bubbles in water is investigated using high-speed photography and pressure measurement via a fiber-optic probe hydrophone. The interaction leads to nonspherical collapse of the bubble with secondary shock wave emission and microjet formation along the LSW propagation direction. The maximum pressure amplification is produced during the collapse phase of the bubble oscillation when the compressive pulse duration of the LSW matches with the forced collapse time of the bubble. PMID:16090745

  4. Shock Wave Interaction with Laser-Generated Single Bubbles

    NASA Astrophysics Data System (ADS)

    Sankin, G. N.; Simmons, W. N.; Zhu, S. L.; Zhong, P.

    2005-07-01

    The interaction of a lithotripter shock wave (LSW) with laser-generated single vapor bubbles in water is investigated using high-speed photography and pressure measurement via a fiber-optic probe hydrophone. The interaction leads to nonspherical collapse of the bubble with secondary shock wave emission and microjet formation along the LSW propagation direction. The maximum pressure amplification is produced during the collapse phase of the bubble oscillation when the compressive pulse duration of the LSW matches with the forced collapse time of the bubble.

  5. Pseudomorphic Single-Quantum-Well Lasers Emit At 980 Nm

    NASA Technical Reports Server (NTRS)

    Larsson, Anders; Forouhar, Siamak; Cody, Jeffrey G.; Lang, Robert J.; Andrekson, Peter A.

    1992-01-01

    Narrow-stripe semiconductor lasers emitting at 980 nm include pseudomorphic In0.2Ga0.8As/GaAs/AlxGa1-xAs graded-index-of-refraction, separate-confinement-heterostructure single quantum well(GRINSCH SQW) with overlaid ridge waveguide. 980 nm chosen as one that yields most efficient pumping because there is no absorption in excited states at this wavelength. Suitable for pumping Er(Sup3+)-doped optical-fiber amplifiers in optical-fiber communication systems and optical phased-array ranging systems.

  6. ECG-triggering of the laser Doppler signal: an approach for perfusion imaging on the beating calf heart

    NASA Astrophysics Data System (ADS)

    Wardell, Karin; Karlsson, Daniel M.; Loenn, Urban; Traff, Stefan; Casimir-Ahn, Henrik

    2001-06-01

    Laser Doppler perfusion imaging (LDPI) has successfully been used to map the myocardial perfusion on patients undergoing coronary bypass surgery on the arrested heart. The need for intra-operative evaluation of graft function is obvious in routine surgery but even more imperative when adapting new surgical techniques where the procedure is performed on the beating heart. When using LDPI on the beating heart, artifacts originating from the movement of the heart are superimposed on the Doppler signal. We have investigated a method to reduce these artifacts by controlling the sampling sequence with ECG-triggering. The method has been assessed in an animal model on the beating calf heart. After sternotomy, an area covering 1 cm2 was imaged at the anterior wall of the left ventricle. In this area, six perfusion images were captured each of them recorded at fixed, but different time intervals in the cardiac cycle. In addition continuous measurements at one spot was done during 1 - 2 minutes. The signal recorded during pumping action was high compared to measurements performed in the same muscle area during infusion of blood with a syringe pump. Repeated measurements captured at a fixed delay time from the R-peak in the same areas at the same heart frequency showed reproducibility. ECG-triggering of the laser Doppler signal is the first step in our attempts to adapt LDPI to enabling assessment of myocardial perfusion on the beating heart. Further technical achievements and in-vivo investigations are, however, needed and will be performed by our research team in future studies.

  7. Fundamental science investigations to develop a 6-MV laser triggered gas switch for ZR: first annual report.

    SciTech Connect

    Warne, Larry Kevin; Van Den Avyle, James A.; Lehr, Jane Marie; Rose, David; Krompholz, Hermann G.; Vela, Russell; Jorgenson, Roy Eberhardt; Timoshkin, Igor (University of Strathclyde, Glasgow, Scotland); Woodworth, Joseph Ray; Prestwich, Kenneth Randel (Voss Scientific, Albuquerque, NM); Krile, John; Given, Martin (University of Strathclyde, Glasgow, Scotland); McKee, G. Randall; Rosenthal, Stephen Edgar; Struve, Kenneth William; Welch, Dale Robert (Voss Scientific, Albuquerque, NM); Benwell, Andrew L. (University of Missouri-Columbia, Columbia, Missouri); Kovaleski, Scott; LeChien, Keith, R.; Johnson, David (Titan Pulse Sciences Division); Fouracre, R.A. (University of Strathclyde, Glasgow, Scotland); Yeckel, Chris (University of Missouri-Columbia, Columbia, Missouri); Wakeland, Peter Eric; Miller, A. R. (Titan Pulse Sciences Division); Hodge, Keith Conquest (Ktech Corporation, Albuquerque, NM); Pasik, Michael Francis; Savage, Mark Edward; Maenchen, John Eric; Curry, Randy D.; Feltz, Greg; Bliss, David Emery; MacGregor, Scott (University of Strathclyde, Glasgow, Scotland); Corley, J. P. (Ktech Corporation, Albuquerque, NM); Anaya, Victor (Ktech Corporation, Albuquerque, NM); Wallace, Zachariah (Ktech Corporation, Albuquerque, NM); Thoma, Carsten (Voss Scientific, Albuquerque, NM); Neuber, Andreas. (Texas Tech University, Lubbock, TX)

    2007-03-01

    In October 2005, an intensive three-year Laser Triggered Gas Switch (LTGS) development program was initiated to investigate and solve observed performance and reliability issues with the LTGS for ZR. The approach taken has been one of mission-focused research: to revisit and reassess the design, to establish a fundamental understanding of LTGS operation and failure modes, and to test evolving operational hypotheses. This effort is aimed toward deploying an initial switch for ZR in 2007, on supporting rolling upgrades to ZR as the technology can be developed, and to prepare with scientific understanding for the even higher voltage switches anticipated needed for future high-yield accelerators. The ZR LTGS was identified as a potential area of concern quite early, but since initial assessments performed on a simplified Switch Test Bed (STB) at 5 MV showed 300-shot lifetimes on multiple switch builds, this component was judged acceptable. When the Z{sub 20} engineering module was brought online in October 2003 frequent flashovers of the plastic switch envelope were observed at the increased stresses required to compensate for the programmatically increased ZR load inductance. As of October 2006, there have been 1423 Z{sub 20} shots assessing a variety of LTGS designs. Numerous incremental and fundamental switch design modifications have been investigated. As we continue to investigate the LTGS, the basic science of plastic surface tracking, laser triggering, cascade breakdown, and optics degradation remain high-priority mission-focused research topics. Significant progress has been made and, while the switch does not yet achieve design requirements, we are on the path to develop successively better switches for rolling upgrade improvements to ZR. This report summarizes the work performed in FY 2006 by the large team. A high-level summary is followed by detailed individual topical reports.

  8. Daily Stress as a Trigger of Migraine Attacks: Results of Thirteen Single-Subject Studies.

    ERIC Educational Resources Information Center

    Kohler, Thomas; Haimerl, Christianne

    1990-01-01

    Six-month longitudinal study examined whether migraine attacks were preceded by or occurred on stressful days. Every evening, 13 patients completed questionnaires assessing daily stress. Analyses on single-subject level tested when attacks occurred. Increased stress was generally not found for Days 2 and 3 before an attack, but often for Day 1 and…

  9. Prolongation of the lifetime of guided discharges triggered in atmospheric air by femtosecond laser filaments up to 130 μs

    NASA Astrophysics Data System (ADS)

    Arantchouk, L.; Honnorat, B.; Thouin, E.; Point, G.; Mysyrowicz, A.; Houard, A.

    2016-04-01

    The triggering and guiding of electric discharges produced in atmospheric air by a compact 100 kV Marx generator is realized in laboratory using an intense femtosecond laser pulse undergoing filamentation. We describe here an approach allowing extending the lifetime of the discharges by injecting a current with an additional circuit. Laser guiding discharges with a length of 8.5 cm and duration of 130 μs were obtained.

  10. Laser light triggers increased Raman amplification in the regime of nonlinear Landau damping.

    PubMed

    Depierreux, S; Yahia, V; Goyon, C; Loisel, G; Masson-Laborde, P-E; Borisenko, N; Orekhov, A; Rosmej, O; Rienecker, T; Labaune, C

    2014-01-01

    Stimulated Raman backscattering (SRS) has many unwanted effects in megajoule-scale inertially confined fusion (ICF) plasmas. Moreover, attempts to harness SRS to amplify short laser pulses through backward Raman amplification have achieved limited success. In high-temperature fusion plasmas, SRS usually occurs in a kinetic regime where the nonlinear response of the Langmuir wave to the laser drive and its host of complicating factors make it difficult to predict the degree of amplification that can be achieved under given experimental conditions. Here we present experimental evidence of reduced Landau damping with increasing Langmuir wave amplitude and determine its effects on Raman amplification. The threshold for trapping effects to influence the amplification is shown to be very low. Above threshold, the complex SRS dynamics results in increased amplification factors, which partly explains previous ICF experiments. These insights could aid the development of more efficient backward Raman amplification schemes in this regime. PMID:24938756

  11. Laser light triggers increased Raman amplification in the regime of nonlinear Landau damping

    PubMed Central

    Depierreux, S.; Yahia, V.; Goyon, C.; Loisel, G.; Masson-Laborde, P. -E.; Borisenko, N.; Orekhov, A.; Rosmej, O.; Rienecker, T.; Labaune, C.

    2014-01-01

    Stimulated Raman backscattering (SRS) has many unwanted effects in megajoule-scale inertially confined fusion (ICF) plasmas. Moreover, attempts to harness SRS to amplify short laser pulses through backward Raman amplification have achieved limited success. In high-temperature fusion plasmas, SRS usually occurs in a kinetic regime where the nonlinear response of the Langmuir wave to the laser drive and its host of complicating factors make it difficult to predict the degree of amplification that can be achieved under given experimental conditions. Here we present experimental evidence of reduced Landau damping with increasing Langmuir wave amplitude and determine its effects on Raman amplification. The threshold for trapping effects to influence the amplification is shown to be very low. Above threshold, the complex SRS dynamics results in increased amplification factors, which partly explains previous ICF experiments. These insights could aid the development of more efficient backward Raman amplification schemes in this regime. PMID:24938756

  12. Laser cutting of carbon fiber reinforced thermo-plastics (CFRTP) by single-mode fiber laser irradiation

    NASA Astrophysics Data System (ADS)

    Niino, Hiroyuki; Kawaguchi, Yoshizo; Sato, Tadatake; Narazaki, Aiko; Kurosaki, Ryozo; Muramatsu, Mayu; Harada, Yoshihisa; Anzai, Kenji; Aoyama, Mitsuaki; Matsushita, Masafumi; Furukawa, Koichi; Nishino, Michiteru; Fujisaki, Akira; Miyato, Taizo; Kayahara, Takashi

    2014-03-01

    We report on the laser cutting of carbon fiber reinforced thermo-plastics (CFRTP) with a cw IR fiber laser (single-mode fiber laser, average power: 350 W). CFRTP is a high strength composite material with a lightweight, and is increasingly being used various applications. A well-defined cutting of CFRTP which were free of debris and thermal-damages around the grooves, were performed by the laser irradiation with a fast beam galvanometer scanning on a multiple-scanpass method.

  13. Laser-induced single point nanowelding of silver nanowires

    NASA Astrophysics Data System (ADS)

    Dai, Shuowei; Li, Qiang; Liu, Guoping; Yang, Hangbo; Yang, Yuanqing; Zhao, Ding; Wang, Wei; Qiu, Min

    2016-03-01

    Nanowelding of nanomaterials opens up an emerging set of applications in transparent conductors, thin-film solar cells, nanocatalysis, cancer therapy, and nanoscale patterning. Single point nanowelding (SPNW) is highly demanded for building complex nanostructures. In this letter, the precise control of SPNW of silver nanowires is explored in depth, where the nanowelding is laser-induced through the plasmonic resonance enhanced photothermal effect. It is shown that the illumination position is a critical factor for the nanowelding process. As an example of performance enhancement, output at wire end can be increased by 65% after welding for a plasmonic nanocoupler. Thus, single point nanowelding technique shows great potentials for high-performance electronic and photonic devices based on nanowires, such as nanoelectronic circuits and plasmonic nanodevices.

  14. Parametric Four-Wave Mixing Using a Single cw Laser

    NASA Astrophysics Data System (ADS)

    Brekke, Erik; Herman, Emily; Alderson, Laura

    2014-05-01

    We present progress in using parametric four-wave mixing in a rubidium cell for the generation of coherent emission at 420 nm and 5.4 μm. A simple system using a single external cavity diode laser at 778 nm and a tapered amplifier supplies the needed optical beams. The efficiency is limited by absorption of the 420 nm beam, with single pass outputs of 40 μW. Optical pumping presents a possibility for increased output powers, but radiation trapping must be overcome at high densities. Several methods for increasing the effectiveness of the process are currently underway. The resulting beam at 420 nm presents an intriguing alternative method of exciting Rydberg states in Rubidium atoms.

  15. Single- and multiphoton infrared laser spectroscopy of atomic negative ions

    NASA Astrophysics Data System (ADS)

    Scheer, Michael

    A pulsed, tunable infrared laser source (0.6-5.2 μm) has been developed on the basis of a commercial dye laser and non-linear optical conversion techniques. This laser source was combined with a keV negative ion beam apparatus in a crossed-beam geometry, with the aim to systematically study several atomic negative ions through a variety of single- and multiphoton detachment experiments. Photodetachment threshold spectra of 21 ionic species (B- , C-, O-, Al- , Si-, Cr-, Co- , Ni-, Cu-, Ge- , Mo-, Rh-, Pd- , Ag-, Sn-, Sb- , Te-, Cs-, Ir- , Pt-, and Bi-) have been recorded, in most cases resulting in very accurate determinations of ionic binding energies, marking substantial improvements over previous experimental values. In fact, several ionic states investigated here had not been observed previously. Different schemes for resonant multiphoton detachment of atomic negative ions were demonstrated for the first time. These studies were conducted with several anions (Si-, Sri- , Sb-, Te-, Ir- , and Pt-) providing highly accurate ionic energy level splittings and clearly demonstrating that multiphoton probes are generally applicable to negative ion structure.

  16. Stepwise Unfolding of Single-Chain Nanoparticles by Chemically Triggered Gates.

    PubMed

    Fischer, Tobias S; Schulze-Sünninghausen, David; Luy, Burkhard; Altintas, Ozcan; Barner-Kowollik, Christopher

    2016-09-01

    The orthogonal, stepwise, and order-independent unfolding of single-chain nanoparticles (SCNPs) is introduced as a key step towards actively controlling the folding dynamics of SCNPs. The SCNPs are compacted by multiple hydrogen bonds and host-guest interactions. Well-defined diblock (AB) and tetrablock (ABCD) copolymers are equipped with orthogonal recognition motifs via modular ligation along the lateral chain. Initially, single-chain folding of the diblock copolymer was induced by the host-guest complexation of benzo-21-crown-7 (B21C7, host) and a secondary ammonium salt (AS, guest), representing an efficient avenue for single-chain collapse. Next, both orthogonal Hamilton wedge (HW) and cyanuric acid (CA) as well as B21C7-AS motifs were employed to generate SCNPs based on the ABCD polymer system. Subsequently, the stepwise dual-gated and order-independent unfolding of the SCNPs was investigated by the addition of external stimuli. The folding and unfolding were explored by 1D (1) H NMR spectroscopy, dynamic light scattering (DLS), and diffusion-ordered NMR spectroscopy (DOSY). PMID:27357944

  17. Single photon laser altimeter simulator and statistical signal processing

    NASA Astrophysics Data System (ADS)

    Vacek, Michael; Prochazka, Ivan

    2013-05-01

    Spaceborne altimeters are common instruments onboard the deep space rendezvous spacecrafts. They provide range and topographic measurements critical in spacecraft navigation. Simultaneously, the receiver part may be utilized for Earth-to-satellite link, one way time transfer, and precise optical radiometry. The main advantage of single photon counting approach is the ability of processing signals with very low signal-to-noise ratio eliminating the need of large telescopes and high power laser source. Extremely small, rugged and compact microchip lasers can be employed. The major limiting factor, on the other hand, is the acquisition time needed to gather sufficient volume of data in repetitive measurements in order to process and evaluate the data appropriately. Statistical signal processing is adopted to detect signals with average strength much lower than one photon per measurement. A comprehensive simulator design and range signal processing algorithm are presented to identify a mission specific altimeter configuration. Typical mission scenarios (celestial body surface landing and topographical mapping) are simulated and evaluated. The high interest and promising single photon altimeter applications are low-orbit (˜10 km) and low-radial velocity (several m/s) topographical mapping (asteroids, Phobos and Deimos) and landing altimetry (˜10 km) where range evaluation repetition rates of ˜100 Hz and 0.1 m precision may be achieved. Moon landing and asteroid Itokawa topographical mapping scenario simulations are discussed in more detail.

  18. Laser phototherapy triggers the production of reactive oxygen species in oral epithelial cells without inducing DNA damage.

    PubMed

    Dillenburg, Caroline Siviero; Almeida, Luciana Oliveira; Martins, Manoela Domingues; Squarize, Cristiane Helena; Castilho, Rogerio Moraes

    2014-04-01

    Laser phototherapy (LPT) is widely used in clinical practice to accelerate healing. Although the use of LPT has advantages, the molecular mechanisms involved in the process of accelerated healing and the safety concerns associated with LPT are still poorly understood. We investigated the physiological effects of LPT irradiation on the production and accumulation of reactive oxygen species (ROS), genomic instability, and deoxyribose nucleic acid (DNA) damage in human epithelial cells. In contrast to a high energy density (20  J/cm²), laser administered at a low energy density (4  J/cm²) resulted in the accumulation of ROS. Interestingly, 4  J/cm² of LPT did not induce DNA damage, genomic instability, or nuclear influx of the BRCA1 DNA damage repair protein, a known genome protective molecule that actively participates in DNA repair. Our results suggest that administration of low energy densities of LPT induces the accumulation of safe levels of ROS, which may explain the accelerated healing results observed in patients. These findings indicate that epithelial cells have an endowed molecular circuitry that responds to LPT by physiologically inducing accumulation of ROS, which triggers accelerated healing. Importantly, our results suggest that low energy densities of LPT can serve as a safe therapy to accelerate epithelial healing. PMID:24781593

  19. Markovian Statistical Data Analysis of Single-Event Upsets Triggered by High Intensity Neutrons

    NASA Technical Reports Server (NTRS)

    Lakdawala, Anushka V.; Zhang, Hong; Gonzalex, Oscar R.; Gray, W. Steven

    2006-01-01

    This paper analyzes data from a single-event upset experiment conducted at the Los Alamos National Laboratory. Statistical tools, based on well-known x(sup 2) hypothesis testing theory, are used to determine if sequences of upsets can be modeled as a homogeneous Markov chain of a specific order. The experiment consisted of radiating a new experimental flight control computer (FCC) with a high intensity neutron beam while the FCC controlled a simulation of a Boeing 737. The analyzed data is a sequence of states that indicates when the FCC is under an upset condition.

  20. A single peptide-major histocompatibility complex ligand triggers digital cytokine secretion in CD4(+) T cells.

    PubMed

    Huang, Jun; Brameshuber, Mario; Zeng, Xun; Xie, Jianming; Li, Qi-jing; Chien, Yueh-hsiu; Valitutti, Salvatore; Davis, Mark M

    2013-11-14

    We have developed a single-molecule imaging technique that uses quantum-dot-labeled peptide-major histocompatibility complex (pMHC) ligands to study CD4(+) T cell functional sensitivity. We found that naive T cells, T cell blasts, and memory T cells could all be triggered by a single pMHC to secrete tumor necrosis factor-α (TNF-α) and interleukin-2 (IL-2) cytokines with a rate of ∼1,000, ∼10,000, and ∼10,000 molecules/min, respectively, and that additional pMHCs did not augment secretion, indicating a digital response pattern. We also found that a single pMHC localized to the immunological synapse induced the slow formation of a long-lasting T cell receptor (TCR) cluster, consistent with a serial engagement mechanism. These data show that scaling up CD4(+) T cell cytokine responses involves increasingly efficient T cell recruitment rather than greater cytokine production per cell. PMID:24120362

  1. Triggering the Growth of Large Single Crystal Graphene by Chemical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Wu, Tianru; Wang, Haomin; Ding, Guqiao; Jiang, Da; Xie, Xiaoming; Jiang, Mianheng

    2013-03-01

    Graphene, a monolayer of sp2 carbon atoms, has been attracting great interests as an ideal two dimensional crystalline material. Fabrication technique for wafer scale graphene via chemical vapor deposition (CVD) was developed several years ago. However, large scale graphene films from CVD method so far are found to be polycrystalline, consisting of numerous grain boundaries, which greatly degrade the electrical and mechanical properties of graphene. Recently, we obtained hexagonal-shaped single-crystal monolayer graphene domains (~1.2 mm). We adapted a strategy to synthesize larger size single crystal grains by regulating the supply of reactants and hytrogen. Nucleation density can be decreased to less than 1000 nuclei /m2. Gradually increase in the supply of reactants could break the equilibrium of growth and etching at the edge of hexagonal-shaped graphene grains. It drives the reaction toward quick growth of graphene domains during the whole CVD process. The graphene grains we obtained show high crystalline quality with high mobility of ~13000 cm2V-1s-1, which is comparable to that of exfoliated graphene. The results achieved will definitely benefit for further practical application of graphene electronics.

  2. Single longitudinal mode operation of semiconductor laser arrays with etalon control

    NASA Technical Reports Server (NTRS)

    Hemmati, H.

    1986-01-01

    A simple method is devised to obtain a single longitudinal output beam from high-power multilongitudinal mode diode laser arrays. Mode control is achieved by simply placing a thin etalon in front of the laser. The three-cavity laser formed by addition of the etalon favors a single longitudinal mode. This technique is applicable to both continuous wave and pulsed laser modes of operation. Experimental results demonstrating the technique along with future work and possible applications are discussed.

  3. Thermally triggered fiber lasers based on secondary-type-In Bragg gratings.

    PubMed

    Feng, Fu-Rong; Ran, Yang; Liang, Yi-Zhi; Gao, Shuai; Feng, Yuan-Hua; Jin, Long; Guan, Bai-Ou

    2016-06-01

    The secondary-type-In grating formed in a small-core photosensitivity active fiber is discovered and investigated. Due to the different grating types, the transmission dip of a secondary grating structure chases and integrates with the type-In grating structure as the temperature increases, which strengthens the reflectivity of the grating. By use of these secondary-type-In gratings as Bragg reflectors, a thermally activated distributed Bragg reflector (DBR) fiber laser is proposed, which can be potentially used in high-temperature alarms and sensors. PMID:27244391

  4. Single-frequency distributed Bragg reflector Nd doped silica fiber laser at 930 nm.

    PubMed

    Fang, Qiang; Xu, Yang; Fu, Shijie; Shi, Wei

    2016-04-15

    We report a single-frequency distributed Bragg reflector (DBR) fiber laser at 930 nm for the first time, to the best of our knowledge. A ∼2.5 cm long commercial highly neodymium-doped silica fiber was utilized as the gain medium to achieve ∼1.9 mW laser output. The single longitudinal mode operation of this laser was verified by a scanning Fabry-Perot interferometer. This fiber laser is suited for seeding high-power 930 nm narrow-linewidth laser amplifiers, which can be used to generate coherent single-frequency pure blue light through frequency doubling. PMID:27082356

  5. Solvent triggered structural diversity of triple-stranded helicates: single molecular magnets.

    PubMed

    Li, Hongfeng; Chen, Peng; Sun, Wenbin; Zhang, Lei; Yan, Pengfei

    2016-02-21

    Multiple-stranded helicates are of interest in respect of their simplicity in geometry and significance in biology and materials. Bis-β-diketones have shown their advantage in terms of structure and geometry in the construction of multiple-stranded helicates, but further studies on their properties are limited due to their poor crystallization. In this study, solvents are found to play a decisive role in the crystallization of triple-stranded helicates. [Dy2(BTB)3(H2O)4] is used as a precursor to solvent-dependently crystallize three complexes [Dy2(BTB)3(CH3OH)4]·3CH3OH (1), [Dy2(BTB)3(DME)2] (2) and [Dy2(BTB)3(DOA)(H2O)2]·4.5DOA (3) (BTB = 3,3'-bis(4,4,4-trifluoro-1,3-dioxobutyl)biphenyl), where the key structural motif of the triple-stranded helicate, [Dy2(BTB)3], is retained. Four methanol molecules are found to ligate to Dy(3+) ions in 1, while each Dy(3+) ion is chelated by one DME molecule in 2. Interestingly, it is observed that 1,4-dioxane as a bridge ligates to two adjacent Dy(3+) ions, giving rise to the formation of a 1D chain structure. Magnetic measurement shows that 1 and 2 display slow magnetic relaxation under zero dc field, while single molecular magnet behavior is obtained for 3 under an applied dc field of 2000 Oe. PMID:26781997

  6. Nanoscale Electron Bunching in Laser-Triggered Ionization Injection in Plasma Accelerators.

    PubMed

    Xu, X L; Pai, C-H; Zhang, C J; Li, F; Wan, Y; Wu, Y P; Hua, J F; Lu, W; An, W; Yu, P; Joshi, C; Mori, W B

    2016-07-15

    Ionization injection is attractive as a controllable injection scheme for generating high quality electron beams using plasma-based wakefield acceleration. Because of the phase-dependent tunneling ionization rate and the trapping dynamics within a nonlinear wake, the discrete injection of electrons within the wake is nonlinearly mapped to a discrete final phase space structure of the beam at the location where the electrons are trapped. This phenomenon is theoretically analyzed and examined by three-dimensional particle-in-cell simulations which show that three-dimensional effects limit the wave number of the modulation to between >2k_{0} and about 5k_{0}, where k_{0} is the wave number of the injection laser. Such a nanoscale bunched beam can be diagnosed by and used to generate coherent transition radiation and may find use in generating high-power ultraviolet radiation upon passage through a resonant undulator. PMID:27472116

  7. Nanoscale Electron Bunching in Laser-Triggered Ionization Injection in Plasma Accelerators

    NASA Astrophysics Data System (ADS)

    Xu, X. L.; Pai, C.-H.; Zhang, C. J.; Li, F.; Wan, Y.; Wu, Y. P.; Hua, J. F.; Lu, W.; An, W.; Yu, P.; Joshi, C.; Mori, W. B.

    2016-07-01

    Ionization injection is attractive as a controllable injection scheme for generating high quality electron beams using plasma-based wakefield acceleration. Because of the phase-dependent tunneling ionization rate and the trapping dynamics within a nonlinear wake, the discrete injection of electrons within the wake is nonlinearly mapped to a discrete final phase space structure of the beam at the location where the electrons are trapped. This phenomenon is theoretically analyzed and examined by three-dimensional particle-in-cell simulations which show that three-dimensional effects limit the wave number of the modulation to between >2 k0 and about 5 k0, where k0 is the wave number of the injection laser. Such a nanoscale bunched beam can be diagnosed by and used to generate coherent transition radiation and may find use in generating high-power ultraviolet radiation upon passage through a resonant undulator.

  8. Single low-dose rHuIL-12 safely triggers multilineage hematopoietic and immune-mediated effects

    PubMed Central

    2014-01-01

    Background Recombinant human interleukin 12 (rHuIL-12) regulates hematopoiesis and cell-mediated immunity. Based on these hematopoietic and immunomodulatory activities, a recombinant human IL-12 (rHuIL-12) is now under development to address the unmet need for a medical countermeasure against the hematopoietic syndrome of the acute radiation syndrome (HSARS) that occurs in individuals exposed to lethal radiation, and also to serve as adjuvant therapy that could provide dual hematopoietic and immunotherapeutic benefits in patients with cancer receiving chemotherapy. We sought to demonstrate in healthy subjects the safety of rHuIL-12 at single, low doses that are appropriate for use as a medical countermeasure for humans exposed to lethal radiation and as an immunomodulatory anti-cancer agent. Methods Two placebo-controlled, double-blinded studies assessed the safety, tolerability, pharmacokinetics and pharmacodynamics of rHuIL-12. The first-in-human (FIH) dose-escalation study randomized subjects to single subcutaneous injections of placebo or rHuIL-12 at 2, 5, 10, and 20 μg doses. Due to toxicity, dose was reduced to 15 μg and then to 12 μg. The phase 1b expansion study randomized subjects to the highest safe and well tolerated dose of 12 μg. Results Thirty-two subjects were enrolled in the FIH study: 4 active and 2 placebo at rHuIL-12 doses of 2, 5, 10, 12, and 15 μg; 1 active and 1 placebo at 20 μg. Sixty subjects were enrolled in the expansion study: 48 active and 12 placebo at 12 μg dose of rHuIL-12. In both studies, the most common adverse events (AEs) related to rHuIL-12 were headache, dizziness, and chills. No immunogenicity was observed. Elimination of rHuIL-12 was biphasic, suggesting significant distribution into extravascular spaces. rHuIL-12 triggered transient changes in neutrophils, platelets, reticulocytes, lymphocytes, natural killer cells, and CD34+ hematopoietic progenitor cells, and induced increases in interferon-γ and C-X-C motif

  9. Imaging the recruitment and loss of proteins and lipids at single sites of calcium-triggered exocytosis.

    PubMed

    Trexler, Adam J; Sochacki, Kem A; Taraska, Justin W

    2016-08-01

    How and when the dozens of molecules that control exocytosis assemble in living cells to regulate the fusion of a vesicle with the plasma membrane is unknown. Here we image with two-color total internal reflection fluorescence microscopy the local changes of 27 proteins at single dense-core vesicles undergoing calcium-triggered fusion. We identify two broad dynamic behaviors of exocytic molecules. First, proteins enriched at exocytic sites are associated with DCVs long before exocytosis, and near the time of membrane fusion, they diffuse away. These proteins include Rab3 and Rab27, rabphilin3a, munc18a, tomosyn, and CAPS. Second, we observe a group of classical endocytic proteins and lipids, including dynamins, amphiphysin, syndapin, endophilin, and PIP2, which are rapidly and transiently recruited to the exocytic site near the time of membrane fusion. Dynamin mutants unable to bind amphiphysin were not recruited, indicating that amphiphysin is involved in localizing dynamin to the fusion site. Expression of mutant dynamins and knockdown of endogenous dynamin altered the rate of cargo release from single vesicles. Our data reveal the dynamics of many key proteins involved in exocytosis and identify a rapidly recruited dynamin/PIP2/BAR assembly that regulates the exocytic fusion pore of dense-core vesicles in cultured endocrine beta cells. PMID:27307587

  10. Mars laser altimeter based on a single photon ranging technique

    NASA Technical Reports Server (NTRS)

    Prochazka, Ivan; Hamal, Karel; Sopko, B.; Pershin, S.

    1993-01-01

    The Mars 94/96 Mission will carry, among others things, the balloon probe experiment. The balloon with the scientific cargo in the gondola underneath will drift in the Mars atmosphere, its altitude will range from zero, in the night, up to 5 km at noon. The accurate gondola altitude will be determined by an altimeter. As the Balloon gondola mass is strictly limited, the altimeter total mass and power consumption are critical; maximum allowed is a few hundred grams a few tens of mWatts of average power consumption. We did propose, design, and construct the laser altimeter based on the single photon ranging technique. Topics covered include the following: principle of operation, altimeter construction, and ground tests.

  11. Laser ablation of single-crystalline silicon by radiation of pulsed frequency-selective fiber laser

    NASA Astrophysics Data System (ADS)

    Veiko, V. P.; Skvortsov, A. M.; Huynh, C. T.; Petrov, A. A.

    2015-07-01

    We have studied the process of destruction of the surface of a single-crystalline silicon wafer scanned by the beam of a pulsed ytterbium-doped fiber laser radiation with a wavelength of λ = 1062 nm. It is established that the laser ablation can proceed without melting of silicon and the formation of a plasma plume. Under certain parameters of the process (radiation power, beam scan velocity, and beam overlap density), pronounced oxidation of silicon microparticles with the formation of a characteristic loose layer of fine powdered silicon dioxide has been observed for the first time. The range of lasing and beam scanning regimes in which the growth of SiO2 layer takes place is determined.

  12. Laser-triggered degelation control of gold nanoparticle embedded peptide organogels.

    PubMed

    Erdogan, Hakan; Sakalak, Huseyin; Yavuz, Mustafa S; Demirel, Gokhan

    2013-06-11

    Further understanding of the interactions between nanoparticles (NPs) and biological molecules offers new possibilities in the applications of nanomedicine and nanodiagnostics. The properties of NPs, including size, shape, and surface functionality, play a decisive role in these interactions. Herein, we evaluated the influences of gold NPs (AuNPs) with different sizes (5-60 nm) and shapes (i.e., spherical, rod, and cage) on the self-assembly of diphenylalanine (Phe-Phe) dipeptides. We found that the size of AuNPs smaller than 10 nm did not affect the self-assembly process of Phe-Phe, while bigger AuNPs (>10 nm) caused the formation of starlike peptide morphologies connected to one center. In the case of shape differences, nanorod and nanocage morphologies acted differently than spherical ones and caused the formation of densely packed, networklike dipeptide morphologies. In addition to these experiments, by combining photothermal properties of AuNPs with a Phe-Phe-based organogel having a thermo-responsive property, we demonstrated that the degelation process of AuNPs embedded organogels may be controlled by laser illumination. Complete degelation was achieved in about 10 min. We believe that such control may open the door to new opportunities for a number of applications, such as controlled release of drugs and tissue engineering. PMID:23706149

  13. Rational design of a comprehensive cancer therapy platform using temperature-sensitive polymer grafted hollow gold nanospheres: simultaneous chemo/photothermal/photodynamic therapy triggered by a 650 nm laser with enhanced anti-tumor efficacy.

    PubMed

    Deng, Xiaoran; Chen, Yinyin; Cheng, Ziyong; Deng, Kerong; Ma, Ping'an; Hou, Zhiyao; Liu, Bei; Huang, Shanshan; Jin, Dayong; Lin, Jun

    2016-03-28

    Combining multi-model treatments within one single system has attracted great interest for the purpose of synergistic therapy. In this paper, hollow gold nanospheres (HAuNs) coated with a temperature-sensitive polymer, poly(oligo(ethylene oxide) methacrylate-co-2-(2-methoxyethoxy)ethyl methacrylate) (p(OEGMA-co-MEMA)), co-loaded with DOX and a photosensitizer Chlorin e6 (Ce6) were successfully synthesized. As high as 58% DOX and 6% Ce6 by weight could be loaded onto the HAuNs-p(OEGMA-co-MEMA) nanocomposites. The grafting polymer brushes outside the HAuNs play the role of "gate molecules" for controlled drug release by 650 nm laser radiation owing to the temperature-sensitive property of the polymer and the photothermal effect of HAuNs. The HAuNs-p(OEGMA-co-MEMA)-Ce6-DOX nanocomposites with 650 nm laser radiation show effective inhibition of cancer cells in vitro and enhanced anti-tumor efficacy in vivo. In contrast, control groups without laser radiation show little cytotoxicity. The nanocomposite demonstrates a way of "killing three birds with one stone", that is, chemotherapy, photothermal and photodynamic therapy are triggered simultaneously by the 650 nm laser stimulation. Therefore, the nanocomposites show the great advantages of multi-modal synergistic effects for cancer therapy by a remote-controlled laser stimulus. PMID:26956400

  14. Simultaneous measurement of two ultrashort laser pulses from a single spectrogram in a single shot

    SciTech Connect

    Kane, D.J.; Rodriguez, G.; Taylor, A.J.; Clement, T.S. ||

    1997-04-01

    Frequency-resolved optical gating (FROG) is a technique that produces a spectrogram of an ultrashort laser pulse. The intensity and phase of the ultrashort laser pulse can be determined through solving for the phase of the spectrogram with an iterative, phase-retrieval algorithm. This work presents a new phase-retrieval algorithm that retrieves both the probe and the gate pulses independently by converting the FROG phase-retrieval problem to an eigenvector problem. The new algorithm is robust and general. It is tested theoretically by use of synthetic data sets and experimentally by use of single-shot, polarization-gate FROG. We independently and simultaneously characterize the electric field amplitude and phase of a pulse (probe) that was passed though 200 mm of BK7 glass and the amplitude of an unchanged pulse (gate) from an amplified Ti:sapphire laser. When the effect of the 200 mm of BK7 glass was removed mathematically from the probe, there was good agreement between the measured gate and the calculated, prechirped probe. {copyright} 1997 Optical Society of America

  15. Low-Cost, Single-Frequency Sources for Spectroscopy Using Conventional Fabry-Perot Diode Lasers

    NASA Technical Reports Server (NTRS)

    Krainak, Michael A.; Duerksen, Gary L.

    1999-01-01

    Commercial (uncoated) Fabry-Perot laser diodes are converted to single-frequency spectroscopy sources by passively locking the laser frequency to the band edge of a fiber Bragg grating, which phase-locks the laser oscillations through self-injection seeding.

  16. Low-Cost, Single-Frequency Sources for Spectroscopy using Conventional Fabry-Perot Diode Lasers

    NASA Technical Reports Server (NTRS)

    Duerksen, Gary L.; Krainak, Michael A.

    1999-01-01

    Commercial (uncoated) Fabry-Perot laser diodes are converted to single-frequency spectroscopy sources by passively locking the laser frequency to the band edge of a fiber Bragg grating, which phase-locks the laser oscillations through self-injection seeding.

  17. Contractions induced by a calcium-triggered release of calcium from the sarcoplasmic reticulum of single skinned cardiac cells.

    PubMed Central

    Fabiato, A; Fabiato, F

    1975-01-01

    1. Fragments of single cardiac cells were obtained by homogenization of ventricular tissue from adult rats. Remaining pieces of sacrolemma were removed by micro-dissection. Tension was recorded from the ends of the skinned (sarcolemma-free) cells with a photodiode force transducer. 2. In the presence of a strong buffering of the free [Ca2+] with 4-0 mM total EGTA, a tonic tension was obtained that increased according to t sigmoid curve when the free ([Ca2+] was increased from 10(-6-75)M to 10(-5-0)M. This curve was not modified by the destruction of the sarcoplasmic reticulum (SR) by the detergent Brij 58. Therefore, the tonic tension corresponded to the direct effect of the free [Ca2+] present in the buffer on the myofilaments. 3. In the presence of a slight buffering of the free [Ca2+] with 0-050 mM total EGTA, cyclic contractions were observed that were attributed to cyclic releases and re-sequestrations of Ca2+ by the SR. The absence of effect of azide and ruthenium red on the cyclic contractions obtained at a free [Ca2+] lower than 10(-6-50)M demonstrated that the mitochondria played no role in the triggering of these contractions. 4. Cyclic contractions were induced by a slight variation of free [Ca2+] in the buffer from 10(-7-65)M to 10(-7-40)M. Their amplitude at 10(-7-40)M free Ca2+ was equal to the tonic tension developed by a free [Ca2+] 20 times higher applied to the myofilaments when the SR was destroyed by detergent or functionally inhibited by high total [EGTA]. It was concluded that these cyclic contractions corresponded to a Ca2+-triggered release of Ca2+ from the SR. 5. The cyclic contractions were induced by the filling of the SR with Ca2+ to a critical level at which it released a fraction of the Ca2+ it contained. Each contraction was followed by a re-sequestration of Ca2+, the kinetics of which conditioned the duration of the cycles. 6. The amplitude of the cyclic contractions increased when the free [Ca2+] that triggered them was increased

  18. Single frequency and wavelength stabilized near infrared laser source for water vapor DIAL remote sensing application

    NASA Astrophysics Data System (ADS)

    Chuang, Ti; Walters, Brooke; Shuman, Tim; Losee, Andrew; Schum, Tom; Puffenberger, Kent; Burnham, Ralph

    2015-02-01

    Fibertek has demonstrated a single frequency, wavelength stabilized near infrared laser transmitter for NASA airborne water vapor DIAL application. The application required a single-frequency laser transmitter operating at 935 nm near infrared (NIR) region of the water vapor absorption spectrum, capable of being wavelength seeded and locked to a reference laser source and being tuned at least 100 pm across the water absorption spectrum for DIAL on/off measurements. Fibertek is building a laser transmitter system based on the demonstrated results. The laser system will be deployed in a high altitude aircraft (ER-2 or UAV) to autonomously perform remote, long duration and high altitude water vapor measurements.

  19. Realization and characterization of single-frequency tunable 637.2 nm high-power laser

    NASA Astrophysics Data System (ADS)

    Wang, Jieying; Bai, Jiandong; He, Jun; Wang, Junmin

    2016-07-01

    We report the preparation of narrow-linewidth 637.2 nm laser device by single-pass sum-frequency generation (SFG) of two infrared lasers at 1560.5 nm and 1076.9 nm in PPMgO:LN crystal. Over 8.75 W of single-frequency continuously tunable 637.2 nm laser is realized, and corresponding optical-optical conversion efficiency is 38.0%. We study the behavior of crystals with different poling periods. The detailed experiments show that the output red lasers have very good power stability and beam quality. This high-performance 637.2 nm laser is significant for the realization of high power ultra-violet (UV) 318.6 nm laser via cavity-enhanced frequency doubling. Narrow-linewidth 318.6 nm laser is important for Rydberg excitation of cesium atoms via single-photon transition.

  20. 2μm single frequency fiber laser based on thulium-doped silica fiber

    NASA Astrophysics Data System (ADS)

    Fu, Shijie; Shi, Wei; Lin, Jichao; Fang, Qiang; Sheng, Quan; Zhang, Haiwei; Wen, Jinwei; Yao, Jianquan

    2016-03-01

    Single-frequency fiber laser operating at 1950 nm has been demonstrated in an all-fiber distributed Bragg reflection (DBR) laser cavity by using a 1.9-cm commercial available Thulium-doped silica fiber, for the first time. The laser was pumped by a 793-nm single-mode diode laser and had a threshold pump power of 75 mW. The maximum output power of the single longitudinal mode laser was 18 mW and the slope efficiency with respect to the launched pump power was 11%. Moreover, the linewidth and relative intensity noise (RIN) at different pump power has been measured and analyzed. The successful demonstration with the Thulium-doped silica fiber used here is considered to further promote the commercialization of single frequency fiber laser at 2 μm.

  1. Combined single-pulse holography and time-resolved laser schlieren for flow visualization

    NASA Technical Reports Server (NTRS)

    Burner, A. W.; Goad, W. K.

    1981-01-01

    A pulsed ruby laser and continuous-wave argon ion laser were used in a combined setup at the Langley Expansion Tube for single pulse holography and time resolved laser schlieren with a common optical axis. The systems can be operated simultaneously for a single run. For a single frame, the pulsed holographic setup offers the options of shadowgraph, Schlieren, and interferometry from the reconstructed hologram as well as the advantage of post-run sensitivity adjustments. For flow establishment studies the time resolved laser Schlieren provides visualization of the flow field every 12.5 microns for up to 80 frames with an exposure time per frame of 5.4 microns.

  2. Femtosecond laser ablation of sapphire on different crystallographic facet planes by single and multiple laser pulses irradiation

    NASA Astrophysics Data System (ADS)

    Qi, Litao; Nishii, Kazuhiro; Yasui, Motohiro; Aoki, Hikoharu; Namba, Yoshiharu

    2010-10-01

    Ablation of sapphire on different crystallographic facet planes by single and multiple laser pulses irradiation was carried out with a femtosecond pulsed laser operating at a wavelength of 780 nm and a pulse width of 164 fs. The quality and morphology of the laser ablated sapphire surface were evaluated by scanning electron microscopy and atomic force microscopy. For single laser pulse irradiation, two ablation phases were observed, which have a strong dependency on the pulse energy. The volume of the ablated craters kept an approximately linear relationship with the pulse energy. The threshold fluences of the two ablation phases on different crystallographic facet planes were calculated from the relationship between the squared diameter of the craters and pulse energy. With multiple laser pulses irradiation, craters free of cracks were obtained in the 'gentle' ablation phase. The threshold fluence for N laser pulses was calculated and found to decrease inversely to the number of laser pulses irradiating on the substrate surface due to incubation effect. The depth of the craters increased with the number of laser pulses until reaching a saturation value. The mechanism of femtosecond laser ablation of sapphire in two ablation phases was discussed and identified as either phase explosion, Coulomb explosion or particle vaporization. The choice of crystallographic facet plane has little effect on the process of femtosecond laser ablation of sapphire when compared with the parameters of the femtosecond laser pulses, such as pulse energy and number of laser pulses. In the 'gentle' ablation phase, laser-induced periodic surface structures (LIPSS) with a spatial period of 340 nm were obtained and the mechanism of the LIPSS formation is discussed. There is a potential application of the femtosecond laser ablation to the fabrication of sapphire-based devices.

  3. Single laser detection of CO and OH via laser-induced fluorescence

    NASA Astrophysics Data System (ADS)

    Mosburger, M.; Sick, V.

    2010-04-01

    Two-photon laser-induced fluorescence detection of carbon monoxide with excitation in the Fourth Positive System near 280 nm is demonstrated in carbon monoxide/nitrogen mixtures at ambient conditions and in a methane/air Bunsen flame. Fully resolved rotational spectra are presented for the A-X (5,0) and (4,0) bands near 279 and 284 nm, respectively. Energy transfer from excited molecular nitrogen to carbon monoxide with subsequent fluorescence from carbon monoxide that was reported for low pressure conditions in the literature has also been observed at atmospheric conditions. It was further demonstrated that overlaps of some CO A-X (4,0) rotational lines with OH A-X (1,0) rotational lines allow simultaneous excitation of both species with a single laser. The fluorescence bands are completely separated, enabling detection without crosstalk. Detection limits are adequate to detect CO in nascent state in a flame and it is expected that for application in high-pressure, low-temperature combustion environments, where high quantities of CO are present, this approach can provide advantages compared to the excitation of CO at shorter wavelengths due to decreased laser beam attenuation.

  4. Single methylation of 23S rRNA triggers late steps of 50S ribosomal subunit assembly.

    PubMed

    Arai, Taiga; Ishiguro, Kensuke; Kimura, Satoshi; Sakaguchi, Yuriko; Suzuki, Takeo; Suzuki, Tsutomu

    2015-08-25

    Ribosome biogenesis requires multiple assembly factors. In Escherichia coli, deletion of RlmE, the methyltransferase responsible for the 2'-O-methyluridine modification at position 2552 (Um2552) in helix 92 of the 23S rRNA, results in slow growth and accumulation of the 45S particle. We demonstrate that the 45S particle that accumulates in ΔrlmE is a genuine precursor that can be assembled into the 50S subunit. Indeed, 50S formation from the 45S precursor could be promoted by RlmE-mediated Um2552 formation in vitro. Ribosomal protein L36 (encoded by rpmJ) was completely absent from the 45S precursor in ΔrlmE, and we observed a strong genetic interaction between rlmE and rpmJ. Structural probing of 23S rRNA and high-salt stripping of 45S components revealed that RlmE-mediated methylation promotes interdomain interactions via the association between helices 92 and 71, stabilized by the single 2'-O-methylation of Um2552, in concert with the incorporation of L36, triggering late steps of 50S subunit assembly. PMID:26261349

  5. Single methylation of 23S rRNA triggers late steps of 50S ribosomal subunit assembly

    PubMed Central

    Arai, Taiga; Ishiguro, Kensuke; Kimura, Satoshi; Sakaguchi, Yuriko; Suzuki, Takeo; Suzuki, Tsutomu

    2015-01-01

    Ribosome biogenesis requires multiple assembly factors. In Escherichia coli, deletion of RlmE, the methyltransferase responsible for the 2′-O-methyluridine modification at position 2552 (Um2552) in helix 92 of the 23S rRNA, results in slow growth and accumulation of the 45S particle. We demonstrate that the 45S particle that accumulates in ΔrlmE is a genuine precursor that can be assembled into the 50S subunit. Indeed, 50S formation from the 45S precursor could be promoted by RlmE-mediated Um2552 formation in vitro. Ribosomal protein L36 (encoded by rpmJ) was completely absent from the 45S precursor in ΔrlmE, and we observed a strong genetic interaction between rlmE and rpmJ. Structural probing of 23S rRNA and high-salt stripping of 45S components revealed that RlmE-mediated methylation promotes interdomain interactions via the association between helices 92 and 71, stabilized by the single 2′-O-methylation of Um2552, in concert with the incorporation of L36, triggering late steps of 50S subunit assembly. PMID:26261349

  6. Continuously tunable single-frequency 1.52-{mu}m diode laser for gas analysis

    SciTech Connect

    Gladyshev, A V; Belovolov, M I; Vasil'ev, Sergei A; Medvedkov, O I; Duraev, V P; Nedelin, E T; Nadezhdinskii, Aleksandr I; Ponurovskii, Ya Ya

    2005-03-31

    A single-frequency continuously tunable diode laser with a hybrid fibre Bragg grating resonator (hybrid laser) is built for recording the absorption line of ammonia. The continuous tuning within 40 GHz (1.33 cm{sup -1}) was achieved for the first time for a hybrid laser emitting 5 mW in the line of width {delta}{nu} {<=} 15 MHz (0.0005 cm{sup -1}) with the side-mode suppression exceeding 20 dB. (lasers)

  7. Study of the parameters of a single-frequency laser for pumping cesium frequency standards

    SciTech Connect

    Zhuravleva, O V; Ivanov, A V; Kurnosov, V D; Kurnosov, K V; Mustafin, I R; Simakov, V A; Chernov, R V; Pleshanov, S A

    2008-04-30

    A model for calculating the parameters of a laser diode with an external fibre cavity containing a fibre Bragg grating (FBG) is presented. It is shown that by using this model, it is possible to obtain single-mode lasing by neglecting the spectral burning of carriers. The regions of the laser-diode current and temperature and the FBG temperature in which the laser can be tuned to the D{sub 2} line of cesium are determined experimentally. (lasers and amplifiers)

  8. Single-mode and tunable microfluidic dye lasers

    NASA Astrophysics Data System (ADS)

    Kristensen, A.; Balslev, S.; Gersborg-Hansen, M.; Bilenberg, B.; Rasmussen, T.; Nilsson, D.

    2006-08-01

    We present a technology for miniaturized, chip-based liquid dye lasers, which may be integrated with microfluidic networks and planar waveguides without addition of further process steps. The microfluidic dye lasers consist of a microfluidic channel with an embedded optical resonator. The lasers are operated with Rhodamine 6G laser dye dissolved in a suitable solvent, such as ethanol or ethylene glycol, and optically pumped at 532 nm with a pulsed, frequency doubled Nd:YAG laser. Both vertically and laterally emitting devices are realized. A vertically emitting Fabry-Perot microcavity laser is integrated with a microfluidic mixer, to demonstrate realtime wavelength tunability. Two major challenges of this technology are addressed: lasing threshold and fluidic handling. Low threshold, in-plane emission and integration with polymer waveguides and microfluidic networks is demonstrated with distributed feed-back lasers. The challenge of fluidic handling is addressed by hybridization with mini-dispensers, and by applying capillary filling of the laser devices.

  9. High brightness fiber laser pump sources based on single emitters and multiple single emitters

    NASA Astrophysics Data System (ADS)

    Scheller, Torsten; Wagner, Lars; Wolf, Jürgen; Bonati, Guido; Dörfel, Falk; Gabler, Thomas

    2008-02-01

    Driven by the potential of the fiber laser market, the development of high brightness pump sources has been pushed during the last years. The main approaches to reach the targets of this market had been the direct coupling of single emitters (SE) on the one hand and the beam shaping of bars and stacks on the other hand, which often causes higher cost per watt. Meanwhile the power of single emitters with 100μm emitter size for direct coupling increased dramatically, which also pushed a new generation of wide stripe emitters or multi emitters (ME) of up to 1000μm emitter size respectively "minibars" with apertures of 3 to 5mm. The advantage of this emitter type compared to traditional bars is it's scalability to power levels of 40W to 60W combined with a small aperture which gives advantages when coupling into a fiber. We show concepts using this multiple single emitters for fiber coupled systems of 25W up to 40W out of a 100μm fiber NA 0.22 with a reasonable optical efficiency. Taking into account a further efficiency optimization and an increase in power of these devices in the near future, the EUR/W ratio pushed by the fiber laser manufacturer will further decrease. Results will be shown as well for higher power pump sources. Additional state of the art tapered fiber bundles for photonic crystal fibers are used to combine 7 (19) pump sources to output powers of 100W (370W) out of a 130μm (250μm) fiber NA 0.6 with nominal 20W per port. Improving those TFB's in the near future and utilizing 40W per pump leg, an output power of even 750W out of 250μm fiber NA 0.6 will be possible. Combined Counter- and Co-Propagated pumping of the fiber will then lead to the first 1kW fiber laser oscillator.

  10. Single-longitudinal-mode Ho:LuAG laser at 2.1 μm

    NASA Astrophysics Data System (ADS)

    Liu, W.; Ju, Y. L.; Dai, T. Y.; Cui, Z.; Wu, J.; Yao, B. Q.; Duan, X. M.; Shen, Y. J.; Wang, Y. Z.

    2016-02-01

    In this letter we report a continuous wave Ho:LuAG laser running on single-longitudinal-mode operation. Two Fabry-Perot etalons were used to narrow the laser line-width. By regulating the angle of the etalons, single-longitudinal-mode lasing was achieved at a wavelength of 2100.65 nm. The maximum power and the slope efficiency of single-longitudinal-mode Ho:LuAG output are 264 mW and 14.5%, respectively. To our knowledge, this is the first time a Ho:LuAG laser with single-longitudinal-mode operation has been obtained.

  11. Single longitudinal mode operation of semiconductor laser arrays with etalon feedback

    NASA Technical Reports Server (NTRS)

    Hemmati, H.

    1987-01-01

    The multiple longitudinal mode output of high-power diode-laser arrays is converted into single mode with 97 percent efficiency by optical feedback from a thin (less than 200-micron thick) etalon external to the laser. The coupled cavities formed by addition of the etalon favor a single longitudinal mode. Single-mode operation is retained at 0.1 MHz pulsed rates. Both the near-field and the far-field patterns of the laser array remain nearly unchanged while the array operates in a single longitudinal mode.

  12. Laser patterning for the study of MSC cardiogenic differentiation at the single-cell level

    PubMed Central

    Ma, Zhen; Liu, Qiuying; Yang, Huaxiao; Runyan, Raymond B; Eisenberg, Carol A; Xu, Meifeng; Borg, Thomas K; Markwald, Roger; Wang, Yifei; Gao, Bruce Z

    2013-01-01

    Mesenchymal stem cells (MSCs) have been cited as contributors to heart repair through cardiogenic differentiation and multiple cellular interactions, including the paracrine effect, cell fusion, and mechanical and electrical couplings. Due to heart–muscle complexity, progress in the development of knowledge concerning the role of MSCs in cardiac repair is heavily based on MSC–cardiomyocyte coculture. In conventional coculture systems, however, the in vivo cardiac muscle structure, in which rod-shaped cells are connected end-to-end, is not sustained; instead, irregularly shaped cells spread randomly, resulting in randomly distributed cell junctions. Consequently, contact-mediated cell–cell interactions (e.g., the electrical triggering signal and the mechanical contraction wave that propagate through MSC–cardiomyocyte junctions) occur randomly. Thus, the data generated on the beneficial effects of MSCs may be irrelevant to in vivo biological processes. In this study, we explored whether cardiomyocyte alignment, the most important phenotype, is relevant to stem cell cardiogenic differentiation. Here, we report (i) the construction of a laser-patterned, biochip-based, stem cell–cardiomyocyte coculture model with controlled cell alignment; and (ii) single-cell-level data on stem cell cardiogenic differentiation under in vivo-like cardiomyocyte alignment conditions. PMID:24527266

  13. Single and Multiphoton Infrared Laser Sectroscopy of Atomic Negative Ions

    NASA Astrophysics Data System (ADS)

    Bilodeau, René C.; Scheer, Michael; Brodie, Cicely A.; Haugen, Harold K.

    1998-05-01

    We have investigated several atomic negative ion species with the aid of a pulsed, tunable infrared laser source (M. Scheer, H.K. Haugen, and D.R. Beck, Phys. Rev. Lett. 79), 4104 (1997); M. Scheer et al, Phys. Rev. Lett. 80, 684 (1998).. In a comprehensive study of the carbon group negative ions (C^-, Si^-, Ge^-, Sn^-, Pb^-) a combination of single and multiphoton techniques was utilized to determine the bound terms and fine structure levels of the p^3 (ground state) configuration. The results comprise accurate electron affinities and the first experimental data on the fine structure of the ^2DJ terms in Si^-, Ge^-, and Sn^-. In addition, photodetachment threshold spectroscopy provided significantly impoved electron affinities for B, Cr, Mo, Ru, Rh, W, and Bi. The detachment cross section of B^-(^3P_J) appeared as a sequence of closely spaced thresholds which enabled the first experimental determination of the ionic fine structure. The detachment cross section of W^- indicates the presence of unexpected and previously unobserved resonances just below the W(5d^56s ^7S_3) threshold.

  14. Optical injection probing of single ZnO tetrapod lasers

    SciTech Connect

    Szarko, Jodi M.; Song, Jae Kyu; Blackledge, Charles Wesley; Swart, Ingmar; Leone, Stephen R.; Li, Shihong; Zhao, Yiping

    2004-11-23

    The properties of zinc oxide (ZnO) nanotetrapod lasers are characterized by a novel ultrafast two-color pump/stimulated emission probe technique. Single legs of tetrapod species are isolated by a microscope objective, pumped by 267 nm pulses, and subjected to a time-delayed 400 nm optical injection pulse, which permits investigation of the ultrafast carrier dynamics in the nanosize materials. With the optical injection pulse included, a large increase in the stimulated emission at 400 nm occurs, which partially depletes the carriers at this wavelength and competes with the normal 390 nm lasing. At the 390 nm lasing wavelengths, the optical injection causes a decrease in the stimulated emission due to the energetic redistribution of the excited carrier depletion, which occurs considerably within the time scale of the subpicosecond duration of the injection pulse. The effects of the optical injection on the spectral gain are employed to probe the lasing dynamics, which shows that the full width at half maximum of the lasing time is 3 ps.

  15. Single-frequency linearly-polarized 1083 nm all fiber nanosecond laser

    NASA Astrophysics Data System (ADS)

    Su, Rongtao; Xu, Jiangmin; Zhou, Pu; Ji, Xiang; Xu, Xiaojun

    2012-12-01

    Single-frequency linearly-polarized 1083 nm all fiber nanosecond master-oscillator power amplifier laser system is demonstrated. A ring laser, whose key components are one saturable absorber and two polarization controllers, delivers a single-frequency continuous wave laser. Using an electro-optic modulator as the modulator, the pulse laser seed is obtained by modulating the CW laser. By amplifying the pulse seed to the average power of 61.6 W in three stages, a single-frequency linearly-polarized laser with pulse duration of 16 ns, repetition rate of 10 MHz and pulse energy of 6.16 μJ is obtained. No nonlinear effect is observed in our experiment. Higher output power can be obtained by increasing LDs of the main amplifier.

  16. Reconfigurable Computing As an Enabling Technology for Single-Photon-Counting Laser Altimetry

    NASA Technical Reports Server (NTRS)

    Powell, Wesley; Hicks, Edward; Pinchinat, Maxime; Dabney, Philip; McGarry, Jan; Murray, Paul

    2003-01-01

    Single-photon-counting laser altimetry is a new measurement technique offering significant advantages in vertical resolution, reducing instrument size, mass, and power, and reducing laser complexity as compared to analog or threshold detection laser altimetry techniques. However, these improvements come at the cost of a dramatically increased requirement for onboard real-time data processing. Reconfigurable computing has been shown to offer considerable performance advantages in performing this processing. These advantages have been demonstrated on the Multi-KiloHertz Micro-Laser Altimeter (MMLA), an aircraft based single-photon-counting laser altimeter developed by NASA Goddard Space Flight Center with several potential spaceflight applications. This paper describes how reconfigurable computing technology was employed to perform MMLA data processing in real-time under realistic operating constraints, along with the results observed. This paper also expands on these prior results to identify concepts for using reconfigurable computing to enable spaceflight single-photon-counting laser altimeter instruments.

  17. Comparison of High Rate Laser Ablation and Resulting Structures Using Continuous and Pulsed Single Mode Fiber Lasers

    NASA Astrophysics Data System (ADS)

    Knebel, T.; Streek, A.; Exner, H.

    This paper compares high rate laser ablation and resulting structures of aluminum by using both a continuous wave and a ns-pulsed single mode fiber laser of high average laser power. Two different scan technologies were applied for fast deflection of the laser beams. In this work, 2.5D laser processing was studied by using a high aperture galvanometer scanner with a maximum scan speed of 18 m/s. By contrast, considerably higher scan speeds up to 1,000 m/s were achieved by using the in-house developed polygon scanner system. The ablation rates and the processing rates per unit area were analyzed by means of the depths of line-scan ablation tracks and laser processed cavities. In addition, SEM photograph of the machining samples will be presented in order to evaluate the machining quality. Finally the feasibility of this high rate technology for industrial application is demonstrated by machining examples.

  18. Developing a pulse trigger generator for a three-electrode spark-gap switch in a transversely excited atmospheric CO2 laser.

    PubMed

    Wang, Jingyuan; Guo, Lihong; Zhang, Xingliang

    2016-04-01

    To improve the probability and stability of breakdown discharge in a three-electrode spark-gap switch for a high-power transversely excited atmospheric CO2 laser and to improve the efficiency of its trigger system, we developed a high-voltage pulse trigger generator based on a two-transistor forward converter topology and a multiple-narrow-pulse trigger method. Our design uses a narrow high-voltage pulse (10 μs) to break down the hyperbaric gas between electrodes of the spark-gap switch; a dry high-voltage transformer is used as a booster; and a sampling and feedback control circuit (mainly consisting of a SG3525 and a CD4098) is designed to monitor the spark-gap switch and control the frequency and the number of output pulses. Our experimental results show that this pulse trigger generator could output high-voltage pulses (number is adjusted) with an amplitude of >38 kV and a width of 10 μs. Compared to a conventional trigger system, our design had a breakdown probability increased by 2.7%, an input power reduced by 1.5 kW, an efficiency increased by 0.12, and a loss reduced by 1.512 kW. PMID:27131693

  19. Developing a pulse trigger generator for a three-electrode spark-gap switch in a transversely excited atmospheric CO2 laser

    NASA Astrophysics Data System (ADS)

    Wang, Jingyuan; Guo, Lihong; Zhang, Xingliang

    2016-04-01

    To improve the probability and stability of breakdown discharge in a three-electrode spark-gap switch for a high-power transversely excited atmospheric CO2 laser and to improve the efficiency of its trigger system, we developed a high-voltage pulse trigger generator based on a two-transistor forward converter topology and a multiple-narrow-pulse trigger method. Our design uses a narrow high-voltage pulse (10 μs) to break down the hyperbaric gas between electrodes of the spark-gap switch; a dry high-voltage transformer is used as a booster; and a sampling and feedback control circuit (mainly consisting of a SG3525 and a CD4098) is designed to monitor the spark-gap switch and control the frequency and the number of output pulses. Our experimental results show that this pulse trigger generator could output high-voltage pulses (number is adjusted) with an amplitude of >38 kV and a width of 10 μs. Compared to a conventional trigger system, our design had a breakdown probability increased by 2.7%, an input power reduced by 1.5 kW, an efficiency increased by 0.12, and a loss reduced by 1.512 kW.

  20. Monolithic 626 nm single-mode AlGaInP DBR diode laser.

    PubMed

    Blume, G; Nedow, O; Feise, D; Pohl, J; Paschke, K

    2013-09-01

    Single-mode lasers below 630 nm are still realized using complex laser systems. We present distributed Bragg reflector (DBR) ridge waveguide lasers (RWL) based on AlGaInP. When packaged into sealed TO-3 housings and cooled internally to about 0°C the DBR-RWL emit more than 50 mW at a wavelength of 626.0 nm into a nearly diffraction-limited single longitudinal mode with a spectral width below 1 MHz. These new monolithic diode lasers have the potential to drastically miniaturize existing set-ups e.g. for quantum information processing. PMID:24104041

  1. Beam pen lithography based on focused laser diode beam with single microlens fabricated by excimer laser.

    PubMed

    Hasan, Md Nazmul; Lee, Yung-Chun

    2015-02-23

    A method is proposed to minimize the focused spot size of an elliptically-diverging laser diode beam by means of a circular aperture and a single plano-convex aspherical microlens. The proposed microlens is fabricated using an excimer laser dragging method and has two different profiles in the x- and y-axis directions. The focused spot size of the beam is examined both numerically and experimentally. The feasibility of the proposed approach for beam pen lithography applications is demonstrated by patterning dotted, straight-line and spiral features on a photo resist layer followed by thin gold layer deposition and metal lift-off. The minimum feature size for dotted pattern is around 2.57 μm, while the minimum line-widths for straight-line and spiral pattern are 3.05 μm and 4.35 μm, respectively. Thus, the technique can be applied to write any arbitrary pattern for high-resolution lithography. PMID:25836486

  2. Coilable single crystals fibers of doped-YAG for high power laser applications

    NASA Astrophysics Data System (ADS)

    Soleimani, Nazila; Ponting, Bennett; Gebremichael, Eminet; Ribuot, Antoine; Maxwell, Gisele

    2014-05-01

    Single crystal fibers are an intermediate between laser crystals and doped glass fibers. They have the advantages of both guiding laser light and matching efficiencies found in bulk crystals, which make them ideal candidates for high-power laser and fiber laser applications. This work focuses on the growth of a flexible fiber with a core of dopant (Er, Nd, Yb, etc.) that will exhibit good wave guiding properties. Direct growth or a combination of growth and cladding experiments are described. Scattering loss measurements at visible wavelengths along with dopant profile characterization are also presented. Laser characterization for these fibers is in progress.

  3. Coilable single crystals fibers of doped-YAG for high power laser applications

    NASA Astrophysics Data System (ADS)

    Soleimani, Nazila; Ponting, Bennett; Gebremichael, Eminet; Ribuot, Antoine; Maxwell, Gisele

    2014-02-01

    Single crystal fibers are an intermediate between laser crystals and doped glass fibers. They have the advantages of both guiding laser light and matching the efficiencies found in bulk crystals, which is making them ideal candidates for high-power laser and fiber laser applications. This work focuses on the growth of a flexible fiber with a core of dopant (Er, Nd, Yb, etc…) that will exhibit good wave guiding properties. Direct growth or a combination of growth and cladding experiments are described. Scattering loss measurements at visible wavelengths along with dopant profile characterization are also presented. Laser characterization for these fibers is in progress.

  4. Single-mode quantum cascade lasers employing a candy-cane shaped monolithic coupled cavity

    NASA Astrophysics Data System (ADS)

    Liu, Peter Q.; Sladek, Kamil; Wang, Xiaojun; Fan, Jen-Yu; Gmachl, Claire F.

    2011-12-01

    We demonstrate single-mode quantum cascade lasers emitting at ˜4.5 μm by employing a monolithic "candy-cane" shaped coupled-cavity consisting of a straight section connecting at one end to a spiral section. The fabrication process is identical to those for simple Fabry-Perot-type ridge lasers. Continuously tunable single-mode emission across ˜8 cm-1 with side mode suppression ratio up to ˜25 dB and a single-mode operating current range of more than 70% above the threshold current is achieved when the lasers are operated in pulsed-mode from 80 K to 155 K.

  5. A stable wavelength-tunable single frequency and single polarization linear cavity erbium-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Feng, T.; Yan, F. P.; Li, Q.; Peng, W. J.; Tan, S. Y.; Feng, S. C.; Liu, P.; Wen, X. D.

    2013-02-01

    We report the configuration and operation of a wavelength-tunable single frequency and single polarization erbium-doped fiber laser (EDFL) with a stable and high optical signal to noise ratio (OSNR) laser output. A narrow-band fiber Bragg grating (NBFBG), a FBG-based Fabry-Perot (FP) filter, a polarization controller (PC) and an unpumped erbium-doped fiber (EDF) as a saturable absorber (SA) are employed to realize stable single frequency lasing operation. An all-fiber polarizer (AFP) is introduced to suppress mode hopping and ensure the single polarization mode operation. By adjusting the length of the NBFBG using a stress adjustment module (SAM), four stable single frequency and single polarization laser outputs at wavelengths of 1544.946, 1545.038, 1545.118 and 1545.182 nm are obtained. At room temperature, performance with an OSNR of larger than 60 dB, power fluctuation of less than 0.04 dB, wavelength variation of less than 0.01 nm for about 5 h measurement, and degree of polarization (DOP) of close to 100% has been experimentally demonstrated for the fiber laser operating at these four wavelengths.

  6. Single-frequency, injection-seeded Er:YAG laser based on a bow-tie ring slave resonator

    NASA Astrophysics Data System (ADS)

    Yao, B. Q.; Deng, Yu; Dai, T. Y.; Duan, X. M.; You-Lun, Ju; Wang, Y. Z.

    2015-08-01

    A diode pumped, injection-seeded Q-switched Er:YAG laser at 1645.2 nm is demonstrated. A single frequency Er:YAG monolithic nonplanar ring oscillator (NPRO) laser emitting at 1645.24 nm with a maximum output power of 500 mW is used as a seed laser. The seed laser output is injected into a bow-tie slave laser, obtaining stable single-frequency Q-switched operation of the Er:YAG laser. The maximum single-frequency Q-switched Er:YAG laser output energy is 2.9 mJ at 100 Hz with a pulse duration of 160 ns.

  7. Self-seeded single-frequency solid-state ring laser and system using same

    DOEpatents

    Dane, C. Brent; Hackel, Lloyd; Harris, Fritz B.

    2007-02-20

    A method of operating a laser to obtain an output pulse having a single wavelength, comprises inducing an intracavity loss into a laser resonator having an amount that prevents oscillation during a time that energy from the pump source is being stored in the gain medium. Gain is built up in the gain medium with energy from the pump source until formation of a single-frequency relaxation oscillation pulse in the resonator. Upon detection of the onset of the relaxation oscillation pulse, the intracavity loss is reduced, such as by Q-switching, so that the built-up gain stored in the gain medium is output from the resonator in the form of an output pulse at a single frequency. An electronically controllable output coupler is controlled to affect output pulse characteristics. The laser acts a master oscillator in a master oscillator power amplifier configuration. The laser is used for laser peening.

  8. Single-mode operation of a zig-zag dye laser

    SciTech Connect

    Mandl, A.; Klimek, D.E.

    1995-05-01

    The authors report single-mode operations of a laser pumped zig-zag dye laser for pulse length {gt}1{mu}s with beam quality close to the diffraction limit. A unique linear optical cavity using counter-propagating orthogonally polarized waves was used. Laser efficiency measurements performed with a stable cavity had outputs of greater than 1.7 J at 568 nm using Pyrromethene-567 dye. The intrinsic laser efficiency was 55% with a slope efficiency of 77%. Single-mode operation was achieved using an unstable resonator with intra-cavity etalons to control the free running modes of the cavity and seeding with a single-mode Kr-ion laser operating at 568 nm. Heterodyne measurements were used to determine that the bandwidth was near the transform limit with the frequency chirping at a rate {approximately}60 MHz/{mu}s. Far-field measurements of the beam quality indicated close to diffraction limited output.

  9. Single-frequency fiber laser at 1950 nm based on thulium-doped silica fiber.

    PubMed

    Fu, Shijie; Shi, Wei; Lin, Jichao; Fang, Qiang; Sheng, Quan; Zhang, Haiwei; Wen, Jinwei; Yao, Jianquan

    2015-11-15

    A single-frequency fiber laser operating at 1950 nm has been demonstrated in an all-fiber distributed Bragg reflection laser cavity by using a 1.9 cm commercially available thulium-doped silica fiber, for the first time, to the best of our knowledge. The laser was pumped by a 793 nm single-mode diode laser and had a threshold pump power of 75 mW. The maximum output power of the single longitudinal mode laser was 18 mW and the slope efficiency with respect to the launched pump power was 11%. Moreover, the linewidth and relative intensity noise at different pump power have been measured and analyzed. PMID:26565855

  10. A tunable and single-longitudinal-mode Ho:YLF laser

    NASA Astrophysics Data System (ADS)

    Dai, T. Y.; Wu, J.; Ju, L.; Zhang, Z. G.; Xu, L. W.; Yao, B. Q.; Wang, Y. Z.

    2016-07-01

    A 1.94 μm Tm-doped fiber laser pumped tunable single-longitudinal-mode Ho:YLF laser with double etalons was reported for the first time. The maximum single-longitudinal-mode output power of 345 mW at 2051.6 nm was achieved at the absorbed pump power of 11.9 W, corresponding to a slope efficiency of 5.5% and an optical conversion efficiency of 2.9%. By regulating the angle of the F-P etalons, the output wavelength of the laser can be tuned from 2051.6 nm to 2063.3 nm. The single-longitude-mode Ho:YLF laser operating at 2 μm can be used as the seed laser source of coherent Doppler lidar, differential absorption lidar and so on.

  11. Optical trapping and surgery of living yeast cells using a single laser

    NASA Astrophysics Data System (ADS)

    Ando, Jun; Bautista, Godofredo; Smith, Nicholas; Fujita, Katsumasa; Daria, Vincent Ricardo

    2008-10-01

    We present optical trapping and surgery of living yeast cells using two operational modes of a single laser. We used a focused laser beam operating in continuous-wave mode for noninvasive optical trapping and manipulation of single yeast cell. We verified that such operational mode of the laser does not cause any destructive effect on yeast cell wall. By changing the operation of the laser to femtosecond-pulsed mode, we show that a tightly focused beam dissects the yeast cell walls via nonlinear absorption. Lastly, using the combined technique of optical microsurgery and trapping, we demonstrate intracellular organelle extraction and manipulation from a yeast cell. The technique established here will be useful as an efficient method for both surgery and manipulation of living cells using a single laser beam.

  12. Single-frequency Yb-doped fiber laser with distributed feedback based on a random FBG

    NASA Astrophysics Data System (ADS)

    Abdullina, S. R.; Vlasov, A. A.; Lobach, I. A.; Belai, O. V.; Shapiro, D. A.; Babin, S. A.

    2016-07-01

    Single-frequency operation of a 1.03 μm fiber laser with random distributed feedback (RDFB) is demonstrated. The laser cavity is based on a 4 cm long fiber Bragg grating (FBG) consisting of 10 homogeneous subgratings with random phase and amplitude of refractive index modulation inscribed in a polarization maintaining (PM) Yb-doped fiber. Such RDFB laser generates single longitudinal mode with output power up to 25 mW, which is 3.5 times higher than that for a DFB laser based on regular π-shifted FBG of the same length in the same fiber. The single-frequency linewidth is measured to be  <100 kHz in both cases. The observed difference of the DFB and RDFB lasers is confirmed by numerical simulation showing different longitudinal distribution of intra-cavity radiation in these cases, analogous to those in the experiment.

  13. Detection of zinc and lead in water using evaporative preconcentration and single-particle laser-induced breakdown spectroscopy

    NASA Astrophysics Data System (ADS)

    Järvinen, Samu T.; Saarela, Jaakko; Toivonen, Juha

    2013-08-01

    A novel laser-induced breakdown spectroscopy (LIBS)-based measurement method for metals in water is demonstrated. In the presented technology a small amount of sodium chloride is dissolved in the sample solution before spraying the sample into a tubular oven. After water removal monodisperse dry NaCl aerosol particles are formed where trace metals are present as additives. A single-particle LIBS analysis is then triggered with a scattering based particle detection system. Benefits are the highly increased metal concentration in the LIBS focal volume and the static NaCl-matrix which can be exploited in the signal processing procedure. Emitted light from the emerged plasma plume is collected with wide angle optics and dispersed with a grating spectrometer. In an aqueous solution, the respective limits of detection for zinc and lead were 0.3 ppm and 0.1 ppm using a relatively low 14 mJ laser pulse energy. Zn/Na peak intensity ratio calibration curve for zinc concentration was also determined and LIBS signal dependence on laser pulse energy was investigated.

  14. All-fiber, narrow linewidth and linearly polarized fiber laser in a single-mode-multimode-single-mode cavity.

    PubMed

    Jiang, Man; Xu, Haiyang; Zhou, Pu; Zhao, Guomin; Gu, Xijia

    2016-08-01

    We report the design of an all-fiber, linearly polarized Yb-doped fiber laser at 1064 nm with a narrow linewidth and high output power required by the master oscillator of the amplifier for high-power spectral beam combining. The laser has achieved linearly polarized output with a polarization extinction ratio of 23 dB, a narrow linewidth of ≤52  pm, and an output power of 32.7 W. Such performance was obtained by the cavity design that incorporated a wavelength-shifted PM fiber Bragg grating pair and single-mode-multimode-single-mode structure. PMID:27505397

  15. Diffractive Combiner of Single-Mode Pump Laser-Diode Beams

    NASA Technical Reports Server (NTRS)

    Liu, Duncan; Wilson, Daniel; Qiu, Yueming; Forouhar, Siamak

    2007-01-01

    An optical beam combiner now under development would make it possible to use the outputs of multiple single-mode laser diodes to pump a neodymium: yttrium aluminum garnet (Nd:YAG) nonplanar ring oscillator (NPRO) laser while ensuring that the laser operates at only a single desired frequency. Heretofore, an Nd:YAG NPRO like the present one has been pumped by a single multimode laser-diode beam delivered via an optical fiber. It would be desirable to use multiple pump laser diodes to increase reliability beyond that obtainable from a single pump laser diode. However, as explained below, simplistically coupling multiple multimode laser-diode beams through a fiber-optic combiner would entail a significant reduction in coupling efficiency, and lasing would occur at one or more other frequencies in addition to the single desired frequency. Figure 1 schematically illustrates the principle of operation of a laser-diode-pumped Nd:YAG NPRO. The laser beam path is confined in a Nd:YAG crystal by means of total internal reflections on the three back facets and a partial-reflection coating on the front facet. The wavelength of the pump beam - 808 nm - is the wavelength most strongly absorbed by the Nd:YAG crystal. The crystal can lase at a wavelength of either 1,064 nm or 1,319 nm - which one depending on the optical coating on the front facet. A thermal lens effect induced by the pump beam enables stable lasing in the lowest-order transverse electromagnetic mode (the TEM00 mode). The frequency of this laser is very stable because of the mechanical stability of the laser crystal and the unidirectional nature of the lasing. The unidirectionality is a result of the combined effects of (1) a Faraday rotation induced by an externally applied magnetic field and (2) polarization associated with non-normal incidence and reflection on the front facet.

  16. Single-mode operation of a long-pulse flashlamp pumped dye laser

    SciTech Connect

    Mandl, A.; Klimek, D.E.; Chou, H.P.; Litzenberger, L.; Wang, Y.

    1995-02-01

    The authors describe the achievement of single-mode operation of a flashlamp pumped long-pulse, {approximately} 700 ns dye laser, with output energy of about 350 mJ using a linear optical cavity with a ``twisted mode`` configuration. Measurements indicate that the laser frequency chirps by about 40 MHz over the entire pulse. Homodyne measurements indicate that the instantaneous bandwidth is close to the transform limit. This represents a significant advance in dye laser performance.

  17. Nanostructuring of single-crystal silicon carbide by picosecond UV laser radiation

    SciTech Connect

    Barmina, E V; Serkov, A A; Shafeev, G A

    2013-12-31

    Surface nanostructures are produced on single-crystal 4H-SiC by laser ablation in water using a Nd : YAG laser (355-nm wavelength, 10-ps pulse duration) as a radiation source. The morphology of the nanostructured surface and the nanostructure size distribution are examined in relation to the energy density of the incident laser beam. The potential of the described process for improving the luminosity of light-emitting diodes on silicon carbide substrates is discussed. (letters)

  18. 7-W single-mode thulium-doped fibre laser pumped at 1230 nm

    SciTech Connect

    Kravtsov, K S; Bufetov, Igor' A; Medvedkov, O I; Dianov, Evgenii M; Yashkov, M V; Gur'yanov, A N

    2005-07-31

    An efficient thulium-doped fibre laser emitting at {approx}2 {mu}m upon pumping into the long-wavelength {sup 3}H{sub 6} {yields} {sup 3}H{sub 5} absorption band of Tm{sup 3+} ions is developed. The maximum output power of the single-mode thulium laser pumped at 1230 nm was 7 W at 1956 nm for a pump conversion efficiency of 35%. (lasers)

  19. Experimental Performance of a Single-Mode Ytterbium-doped Fiber Ring Laser with Intracavity Modulator

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Camp, Jordan

    2012-01-01

    We have developed a linearly polarized Ytterbium-doped fiber ring laser with a single longitudinal mode output at 1064 run. A fiber-coupled intracavity phase modulator ensured mode-hop free operation and allowed fast frequency tuning. The fiber laser was locked with high stability to an iodine-stabilized laser, showing a frequency noise suppression of a factor approx 10 (exp 5) at 1 mHz

  20. Compact, multipass, single transverse mode CO/sub 2/ laser

    SciTech Connect

    Xin, J.G.; Hall, D.R.

    1987-08-17

    We report the design and basic operating characteristics of a co-axial radio-frequency discharge carbon dioxide laser which employs a multipass Herriott cell folding system within a linear resonator. A continuous wave laser power output of 65 W was obtained from a device 35 cm in length in a high-quality TEM/sub 00/ mode without gas flow. The characteristics of transverse rf discharges and the image rotation properties of such resonators indicate that this approach may be scalable to provide much higher laser powers with excellent transverse mode properties.

  1. Applications of a single-longitudinal-mode alexandrite laser for diagnostics of parameters of combustion interest

    NASA Astrophysics Data System (ADS)

    Li, Z. S.; Afzelius, M.; Zetterberg, J.; Aldén, M.

    2004-10-01

    We report on the applications of a single-longitudinal-mode (SLM) pulsed alexandrite laser system for diagnostics of parameters of flow/combustion interest. The laser system is characterized by its narrow linewidth, high peak power, and broad tunablity. The absolute frequency of the laser output was monitored by a wavelength diagnostic system, which included a high-resolution confocal etalon and a molecular iodine laser-induced fluorescence (LIF) detection system. Different nonlinear frequency conversion schemes were used to cover a large frequency range from the infrared to the deep UV. The versatility of the laser system for flow/combustion diagnostics is demonstrated in three applications, namely filtered Rayleigh scattering, high-resolution Doppler-free two-photon LIF of CO, and infrared LIF and polarization spectroscopy of CO2. The potential impacts of using this SLM laser system in laser flow/combustion diagnostic applications are discussed.

  2. A Single-Lens Laser Beam Shaper for Uniform Flat-Top Profiles

    SciTech Connect

    Zhang, Shukui; Neil, George; Michelle D. Shinn

    2006-01-01

    A novel design is presented for a simple laser beam shaping system. Unlike earlier reports and designs, we prove it is possible to convert a laser beam from a non-uniform profile to a uniform flat-top distribution with a single aspherical lens.

  3. Single-frequency ytterbium-doped fiber laser at 976 nm

    NASA Astrophysics Data System (ADS)

    Zhu, X.; Shi, W.; Zong, J.; Nguyen, D.; Norwood, R. A.; Chavez-Pirson, A.; Peyghambarian, N.

    2013-02-01

    Linearly polarized wavelength stable single frequency ytterbium (Yb3+) doped fiber lasers below 1 μm, namely threelevel Yb3+ fiber lasers, are highly demanded for nonlinear wavelength conversion to generate coherent blue light or even deep ultraviolet coherent sources. We present performance of a 976 nm single-frequency core-pumped distributed Bragg reflector (DBR) fiber laser consisting of a 2-cm long highly ytterbium-doped phosphate fiber and a pair of silica fiber Bragg gratings (FBGs) and their use for frequency doubling experiment. The high reflection (HR > 99%) and partial reflection (PR = 60%) FBGs were cleaved very close to the index modulation region and directly spliced to a 2-cm-long highly Yb3+-doped phosphate fiber. Over 100 mW of linearly polarized output with a linewidth less than 2 kHz can be obtained when the launched pump power is about 450 mW. The efficiency of the 976 nm single-frequency fiber laser (the output power vs the launched pump power) is about 25%. The relative intensity noise was measured to be -110 dB/Hz at 1 MHz and the variation of the center wavelength is less than 0.0005 nm during a measurement period of 2.5 hours. This single-frequency fiber laser has an SNR of over 50 dB and there is no strong ASE or spurious lasing at long wavelengths even at the maximum pump power. This all-fiber single-frequency DBR laser with attractive features can be used for efficient blue and UV generation through nonlinear frequency conversion. Moreover, this high-performance 976 nm single-frequency fiber laser can be used as a single-frequency, low RIN pump laser for long wavelength Yb3+-, Er3+-, or Yb3+/Er3+-doped fiber lasers and amplifiers.

  4. Continuous operation of monolithic dynamic-single-mode coupled-cavity lasers

    SciTech Connect

    Coldren, L.A.; Ebeling, K.J.; Rentschler, J.A.; Burrus, C.A.; Wilt, D.P.

    1984-02-15

    The first cw monolithic two-section lasers were fabricated using reactive-ion-etched grooves in buried-crescent wafers. Tunable single-mode selection with spurious mode levels down approx.20 dB was demonstrated under modulation.

  5. Rational design of a comprehensive cancer therapy platform using temperature-sensitive polymer grafted hollow gold nanospheres: simultaneous chemo/photothermal/photodynamic therapy triggered by a 650 nm laser with enhanced anti-tumor efficacy

    NASA Astrophysics Data System (ADS)

    Deng, Xiaoran; Chen, Yinyin; Cheng, Ziyong; Deng, Kerong; Ma, Ping'an; Hou, Zhiyao; Liu, Bei; Huang, Shanshan; Jin, Dayong; Lin, Jun

    2016-03-01

    Combining multi-model treatments within one single system has attracted great interest for the purpose of synergistic therapy. In this paper, hollow gold nanospheres (HAuNs) coated with a temperature-sensitive polymer, poly(oligo(ethylene oxide) methacrylate-co-2-(2-methoxyethoxy)ethyl methacrylate) (p(OEGMA-co-MEMA)), co-loaded with DOX and a photosensitizer Chlorin e6 (Ce6) were successfully synthesized. As high as 58% DOX and 6% Ce6 by weight could be loaded onto the HAuNs-p(OEGMA-co-MEMA) nanocomposites. The grafting polymer brushes outside the HAuNs play the role of ``gate molecules'' for controlled drug release by 650 nm laser radiation owing to the temperature-sensitive property of the polymer and the photothermal effect of HAuNs. The HAuNs-p(OEGMA-co-MEMA)-Ce6-DOX nanocomposites with 650 nm laser radiation show effective inhibition of cancer cells in vitro and enhanced anti-tumor efficacy in vivo. In contrast, control groups without laser radiation show little cytotoxicity. The nanocomposite demonstrates a way of ``killing three birds with one stone'', that is, chemotherapy, photothermal and photodynamic therapy are triggered simultaneously by the 650 nm laser stimulation. Therefore, the nanocomposites show the great advantages of multi-modal synergistic effects for cancer therapy by a remote-controlled laser stimulus.Combining multi-model treatments within one single system has attracted great interest for the purpose of synergistic therapy. In this paper, hollow gold nanospheres (HAuNs) coated with a temperature-sensitive polymer, poly(oligo(ethylene oxide) methacrylate-co-2-(2-methoxyethoxy)ethyl methacrylate) (p(OEGMA-co-MEMA)), co-loaded with DOX and a photosensitizer Chlorin e6 (Ce6) were successfully synthesized. As high as 58% DOX and 6% Ce6 by weight could be loaded onto the HAuNs-p(OEGMA-co-MEMA) nanocomposites. The grafting polymer brushes outside the HAuNs play the role of ``gate molecules'' for controlled drug release by 650 nm laser radiation

  6. Modeling and optimization of single-pass laser amplifiers for high-repetition-rate laser pulses

    SciTech Connect

    Ozawa, Akira; Udem, Thomas; Zeitner, Uwe D.; Haensch, Theodor W.; Hommelhoff, Peter

    2010-09-15

    We propose a model for a continuously pumped single-pass amplifier for continuous and pulsed laser beams. The model takes into account Gaussian shape and focusing geometry of pump and seed beam. As the full-wave simulation is complex we have developed a largely simplified numerical method that can be applied to rotationally symmetric geometries. With the tapered-shell model we treat (focused) propagation and amplification of an initially Gaussian beam in a gain crystal. The implementation can be done with a few lines of code that are given in this paper. With this code, a numerical parameter optimization is straightforward and example results are shown. We compare the results of our simple model with those of a full-wave simulation and show that they agree well. A comparison of model and experimental data also shows good agreement. We investigate in detail different regimes of amplification, namely the unsaturated, the fully saturated, and the intermediate regime. Because the amplification process is affected by spatially varying saturation and exhibits a nonlinear response against pump and seed power, no analytical expression for the expected output is available. For modeling of the amplification we employ a four-level system and show that if the fluorescence lifetime of the gain medium is larger than the inverse repetition rate of the seed beam, continuous-wave amplification can be employed to describe the amplification process of ultrashort pulse trains. We limit ourselves to this regime, which implies that if titanium:sapphire is chosen as gain medium the laser repetition rate has to be larger than a few megahertz. We show detailed simulation results for titanium:sapphire for a large parameter set.

  7. Gravitational Wave Detection with Single-Laser Atom Interferometers

    NASA Technical Reports Server (NTRS)

    Yu, Nan; Tinto, Massimo

    2011-01-01

    A new design for a broadband detector of gravitational radiation relies on two atom interferometers separated by a distance L. In this scheme, only one arm and one laser are used for operating the two atom interferometers. The innovation here involves the fact that the atoms in the atom interferometers are not only considered as perfect test masses, but also as highly stable clocks. Atomic coherence is intrinsically stable, and can be many orders of magnitude more stable than a laser.

  8. UV-Triggered Self-Healing of a Single Robust SiO2 Microcapsule Based on Cationic Polymerization for Potential Application in Aerospace Coatings.

    PubMed

    Guo, Wanchun; Jia, Yin; Tian, Kesong; Xu, Zhaopeng; Jiao, Jiao; Li, Ruifei; Wu, Yuehao; Cao, Ling; Wang, Haiyan

    2016-08-17

    UV-triggered self-healing of single microcapsules has been a good candidate to enhance the life of polymer-based aerospace coatings because of its rapid healing process and healing chemistry based on an accurate stoichiometric ratio. However, free radical photoinitiators used in single microcapsules commonly suffer from possible deactivation due to the presence of oxygen in the space environment. Moreover, entrapment of polymeric microcapsules into coatings often involves elevated temperature or a strong solvent, probably leading to swelling or degradation of polymer shell, and ultimately the loss of active healing species into the host matrix. We herein describe the first single robust SiO2 microcapsule self-healing system based on UV-triggered cationic polymerization for potential application in aerospace coatings. On the basis of the similarity of solubility parameters of the active healing species and the SiO2 precursor, the epoxy resin and cationic photoinitiator are successfully encapsulated into a single SiO2 microcapsule via a combined interfacial/in situ polymerization. The single SiO2 microcapsule shows solvent resistance and thermal stability, especially a strong resistance for thermal cycling in a simulated space environment. In addition, the up to 89% curing efficiency of the epoxy resin in 30 min, and the obvious filling of scratches in the epoxy matrix demonstrate the excellent UV-induced healing performance of SiO2 microcapsules, attributed to a high load of healing species within the capsule (up to 87 wt %) and healing chemistry based on an accurate stoichiometric ratio of the photoinitiator and epoxy resin at 9/100. More importantly, healing chemistry based on a UV-triggered cationic polymerization mechanism is not sensitive to oxygen, extremely facilitating future embedment of this single SiO2 microcapsule in spacecraft coatings to achieve self-healing in a space environment with abundant UV radiation and oxygen. PMID:27463101

  9. Generation of single longitudinal mode in a pulsed passively Q -switched Nd:YAG laser

    SciTech Connect

    Hariri, A.; Soltanmoradi, F.; Nayeri, M. )

    1990-08-01

    It is shown that a single longitudinal mode in a passively {ital Q}-switch Nd:YAG laser can be obtained by adjusting an intracavity saturable absorber gelatin film (BDN) to work as a mirror in a three-mirror Fabry--Perot resonator. With a 0.13-mm-thick gelatin film of 40% unsaturated transmission, a temporally smooth single-laser pulse of {similar to}10 ns duration has been obtained.

  10. A 980 nm pseudomorphic single quantum well laser for pumping erbium-doped optical fiber amplifiers

    NASA Technical Reports Server (NTRS)

    Larsson, A.; Forouhar, S.; Cody, J.; Lang, R. J.; Andrekson, P. A.

    1990-01-01

    The authors have fabricated ridge waveguide pseudomorphic InGaAs/GaAs/AlGaAs GRIN-SCH SQW (graded-index separate-confinement-heterostructure single-quantum-well) lasers, emitting at 980 nm, with a maximum output power of 240 mW from one facet and a 22 percent coupling efficiency into a 1.55-micron single-mode optical fiber. These lasers satisfy the requirements on efficient and compact pump sources for Er3+-doped fiber amplifiers.

  11. Single Longitudinal Mode, High Repetition Rate, Q-switched Ho:YLF Laser for Remote Sensing

    NASA Technical Reports Server (NTRS)

    Bai, Yingxin; Yu, Jirong; Petzar, Paul; Petros, M.; Chen, Songsheng; Trieu, Bo; Lee, Nyung; Singh, U.

    2009-01-01

    Ho:YLF/LuLiF lasers have specific applications for remote sensing such as wind-speed measurement and carbon dioxide (CO2) concentration measurement in the atmosphere because the operating wavelength (around 2 m) is located in the eye-safe range and can be tuned to the characteristic lines of CO2 absorption and there is strong backward scattering signal from aerosol (Mie scattering). Experimentally, a diode pumped Ho:Tm:YLF laser has been successfully used as the transmitter of coherent differential absorption lidar for the measurement of with a repetition rate of 5 Hz and pulse energy of 75 mJ [1]. For highly precise CO2 measurements with coherent detection technique, a laser with high repetition rate is required to averaging out the speckle effect [2]. In addition, laser efficiency is critically important for the air/space borne lidar applications, because of the limited power supply. A diode pumped Ho:Tm:YLF laser is difficult to efficiently operate in high repetition rate due to the large heat loading and up-conversion. However, a Tm:fiber laser pumped Ho:YLF laser with low heat loading can be operated at high repetition rates efficiently [3]. No matter whether wind-speed or carbon dioxide (CO2) concentration measurement is the goal, a Ho:YLF/LuLiF laser as the transmitter should operate in a single longitudinal mode. Injection seeding is a valid technique for a Q-switched laser to obtain single longitudinal mode operation. In this paper, we will report the new results for a single longitudinal mode, high repetition rate, Q-switched Ho:YLF laser. In order to avoid spectral hole burning and make injection seeding easier, a four mirror ring cavity is designed for single longitudinal mode, high repetition rate Q-switched Ho:YLF laser. The ramp-fire technique is chosen for injection seeding.

  12. Technology and engineering aspects of high power pulsed single longitudinal mode dye lasers

    NASA Astrophysics Data System (ADS)

    Rawat, V. S.; Mukherjee, Jaya; Gantayet, L. M.

    2015-09-01

    Tunable single mode pulsed dye lasers are capable of generating optical radiations in the visible range having very small bandwidths (transform limited), high average power (a few kW) at a high pulse repetition rate (a few tens of kHz), small beam divergence and relatively higher efficiencies. These dye lasers are generally utilized laser dyes dissolved in solvents such as water, heavy water, ethanol, methanol, etc. to provide a rapidly flowing gain medium. The dye laser is a versatile tool, which can lase either in the continuous wave (CW) or in the pulsed mode with pulse duration as small as a few tens of femtoseconds. In this review, we have examined the several cavity designs, various types of gain mediums and numerous types of dye cell geometries for obtaining the single longitudinal mode pulsed dye laser. Different types of cavity configuration, such as very short cavity, short cavity with frequency selective element and relatively longer cavity with multiple frequency selective elements were reviewed. These single mode lasers have been pumped by all kinds of pumping sources such as flash lamps, Excimer, Nitrogen, Ruby, Nd:YAG, Copper Bromide and Copper Vapor Lasers. The single mode dye lasers are either pumped transversely or longitudinally to the resonator axis. The pulse repletion rate of these pump lasers were ranging from a few Hz to a few tens of kHz. Physics technology and engineering aspects of tuning mechanism, mode hop free scanning and dye cell designs are also presented in this review. Tuning of a single mode dye laser with a resolution of a few MHz per step is a technologically challenging task, which is discussed here.

  13. 11 W single gain-chip dilute nitride disk laser emitting around 1180 nm.

    PubMed

    Korpijärvi, Ville-Markus; Leinonen, Tomi; Puustinen, Janne; Härkönen, Antti; Guina, Mircea D

    2010-12-01

    We report power scaling experiments of a GaInNAs/GaAs-based semiconductor disk laser operating at ~1180 nm. Using a single gain chip cooled to mount temperature of ~10 °C we obtained 11 W of output power. For efficient thermal management we used a water-cooled microchannel mount and an intracavity diamond heat spreader. Laser performance was studied using different spot sizes of the pump beam on the gain chip and different output couplers. Intracavity frequency-doubling experiments led to generation of ~6.2 W of laser radiation at ~590 nm, a wavelength relevant for the development of sodium laser guide stars. PMID:21164909

  14. Efficient single-pass resonantly-pumped Ho:YAG laser

    NASA Astrophysics Data System (ADS)

    Elder, Ian; Kendall, Timothy

    2012-09-01

    A simple scheme for efficient generation of two micron laser radiation is reported. Using a thulium fibre laser to pump a Q-switched Ho:YAG laser 31.7 W of average output power is achieved with an M2 of 1.5 (an optical-to-optical conversion efficiency of 67% in terms of absorbed pump power) at a wavelength of 2.1 μm. A single-pass pump geometry is used, eliminating the risk of feedback of unabsorbed light into the fibre laser.

  15. Single-frequency fiber laser operating at 2.9 μm.

    PubMed

    Hudson, Darren D; Williams, Robert J; Withford, Michael J; Jackson, Stuart D

    2013-07-15

    We report the demonstration of a single-longitudinal-mode fiber laser operating at 2914 nm, which exhibits a spectrometer-limited linewidth of <0.4 nm, in a 49 mm long holmium/praseodymium co-doped ZBLAN fiber. Narrow-linewidth feedback is provided by a fiber Bragg grating inscribed directly in the ZBLAN fiber using the femtosecond laser point-by-point technique. Measurements of the temporal stability and coherence confirm that the laser is operating on a single longitudinal mode. PMID:23939057

  16. Single-growth embedded epitaxy AlGaAs injection lasers with extremely low threshold currents

    SciTech Connect

    Katz, J.; Margalit, S.; Wilt, D.; Chen, P.C.; Yariv, A.

    1980-12-01

    A new type of strip-geometry AlGaAs double-heterostructure laser with an embedded optical waveguide has been developed. The new structure is fabricated using a single step of epitaxial growth. Lasers with threshold currents as low as 9.5 mA (150 ..mu..m long) were obtained. These lasers exhibit operation in a single spatial and longitudinal mode, have differential quantum efficiencies exceeding 45%, and a characteristic temperature of 175/sup 0/ C. They emit more than 12 mW/facet of optical power without any kinks.

  17. Formation of single-mode laser in transverse plane of perovskite microwire via micromanipulation.

    PubMed

    Wang, Kaiyang; Gu, Zhiyuan; Liu, Shuai; Li, Jiankai; Xiao, Shumin; Song, Qinghai

    2016-02-01

    The synthesized perovskites are randomly distributed and their optical properties are fixed after synthesis. Here we demonstrate the tailoring of lasing properties of perovskite microwire via micromanipulation. One microwire has been lifted by a tungsten probe and repositioned on a nearby perovskite microplate with one end suspended in air. Consequently, the conventional Fabry-Perot lasers are completely suppressed and a single laser peak has been observed. The numerical calculations reveal that the single-mode laser is formed by the whispering-gallery mode in the transverse plane of microwire. Our research provides a simple way to tailor the properties of microwire postsynthesis. PMID:26907422

  18. Cell perforation mediated by plasmonic bubbles generated by a single near infrared femtosecond laser pulse.

    PubMed

    Boutopoulos, Christos; Bergeron, Eric; Meunier, Michel

    2016-01-01

    We report on transient membrane perforation of living cancer cells using plasmonic gold nanoparticles (AuNPs) enhanced single near infrared (NIR) femtosecond (fs) laser pulse. Under optimized laser energy fluence, single pulse treatment (τ = 45 fs, λ = 800 nm) resulted in 77% cell perforation efficiency and 90% cell viability. Using dark field and ultrafast imaging, we demonstrated that the generation of submicron bubbles around the AuNPs is the necessary condition for the cell membrane perforation. AuNP clustering increased drastically the bubble generation efficiency, thus enabling an effective laser treatment using low energy dose in the NIR optical therapeutical window. PMID:26199220

  19. Highly coherent long cavity GaAs/AlGaAs single-quantum-well lasers

    SciTech Connect

    Larsson, A. ); Andrekson, P.A.; Jonsson, B.; Lindstrom, C. )

    1989-09-01

    The authors report on measurements of the spectral properties of ridge waveguide graded index separate confinement heterostructure single-quantum-well GaAs/AlGaAs lasers. Long cavity lasers (800{mu}m) exhibit remarkably pure single-longitudinal-mode spectra under continuous operation in spite of the short cavity mode spacing. At an output power of 5 mW, the sidemode suppression exceeds 24 dB and the linewidth is 1.5 MHz. This is among the narrowest linewidths reported for solitary AlGaAs lasers. The linewidth-power product is 6.4 MHz mW. Measurements of the linewidth-power product as a function of cavity length L gives an L/sup -2/ dependence in agreement with theory for lasers with small internal loss. No significant deviation from this dependence was observed for lasers short enough to operate at the second quantized state. The results are also used to deduce the linewidth enhancement factor {alpha} at the gain peak wavelength and its dependence on the excitation level. The sublinear gain-carrier density relation in the single quantum well results in an increase in a with increasing carrier density (decreasing cavity length) in contrast to conventional double heterostructure lasers and multiple-quantum-well lasers. In addition, a decrease in {alpha} was observed for lasers operating at the second quantized state due to recovery of the differential gain.

  20. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Investigation of single-frequency semiconductor lasers with a fiber Michelson interferometer

    NASA Astrophysics Data System (ADS)

    Belovolov, M. I.; Gur'yanov, A. N.; Gusovskiĭ, D. D.; Dianov, Evgenii M.; Kuznetsov, A. V.; Pencheva, V. Kh; Prokhorov, A. M.

    1987-04-01

    A fiber Michelson interferometer, which is an analog of a scanning Michelson interferometer, was constructed from single-mode fiber waveguides and several highly directional Y-type couplers operating at the wavelength of 0.85 μ. It was found that this interferometer could be used to investigate the coherence of radiation from single-frequency lasers with a spectral line width in the range from 10 kHz to 1 GHz. The experimental dependences of the degree of coherence on the optical path difference were determined for cw single-frequency AlGaAs double heterostructure lasers with an external dispersive resonator, operating in the regime of self-stabilization of single-frequency emission. It was found that the width of the spectral lines was between 10 kHz and 1 MHz, and that the line profiles were Lorentzian.

  1. Stability of short, single-mode erbium-doped fiber lasers

    SciTech Connect

    Svalgaard, M.; Gilbert, S.L.

    1997-07-01

    We conducted a detailed study of the stability of short, erbium-doped fiber lasers fabricated with two UV-induced Bragg gratings written into the doped fiber. We find that the relative intensity noise of single-longitudinal-mode fiber grating lasers is approximately 3 orders of magnitude lower than that of a single-frequency 1.523-{mu}m helium-neon laser. The frequency noise spectrum contains few resonances, none of which exceeds 0.6 kHz/Hz{sup 1/2} rms; the integrated rms frequency noise from 50 Hz to 63 kHz is 36 kHz. We also demonstrate a simple method for monitoring the laser power and number of oscillating modes during laser fabrication. {copyright} 1997 Optical Society of America

  2. Single-beam Denisyuk holograms recording with pulsed 30Hz RGB laser

    NASA Astrophysics Data System (ADS)

    Zacharovas, Stanislovas; Bakanas, Ramūnas; Stankauskas, Algimantas

    2016-03-01

    It is well known fact that holograms can be recorded either by continuous wave (CW) laser, or by single pulse coming from pulsed laser. However, multi-pulse or multiple-exposure holograms were used only in interferometry as well as for information storage. We have used Geola's single longitudinal mode pulsed RGB laser to record Denisyuk type holograms. We successfully recorded objects situated at the distance of more than 30cm, employing the multi-pulse working regime of the laser. To record Denisyuk hologram we have used 50 ns duration 440, 660nm wavelength and 35ns duration 532nm wavelength laser pulses at the repetition rate of 30Hz. As photosensitive medium we have used Slavich-Geola PFG-03C glass photoplate. Radiations with different wavelengths were mixed into "white" beam, collimated and directed onto the photoplate. For further objects illumination an additional flat silver coated mirror was used.

  3. Coilable single crystal fibers of doped-YAG for high power laser applications

    NASA Astrophysics Data System (ADS)

    Maxwell, Gisele; Soleimani, Nazila; Ponting, Bennett; Gebremichael, Eminet

    2013-05-01

    Single crystal fibers are an intermediate between laser crystals and doped glass fibers. They can combine the advantages of both by guiding laser light and matching the efficiencies found in bulk crystals, making them ideal candidates for high-power laser and fiber laser applications. In particular, a very interesting feature of single crystal fiber is that they can generate high power in the eye-safe range (Er:YAG) with a high efficiency, opening new possibilities for portable directed energy weapons. This work focuses on the growth of a flexible fiber with a core of dopant (Er, Nd, Yb, etc…) that will exhibit good waveguiding properties. Direct growth or a combination of growth and cladding experiments are described. We have, to date, demonstrated the growth of a flexible foot long 45 microns doped YAG fiber. Scattering loss measurements at visible wavelengths along with dopant profile characterization are also presented. Laser characterization for these fibers is in progress.

  4. 976 nm single-frequency distributed Bragg reflector fiber laser.

    PubMed

    Zhu, Xiushan; Shi, Wei; Zong, Jie; Nguyen, Dan; Norwood, Robert A; Chavez-Pirson, Arturo; Peyghambarian, N

    2012-10-15

    A single-frequency distributed Bragg reflector (DBR) fiber laser at 976 nm was developed with a 2 cm long highly ytterbium-doped phosphate fiber and a pair of silica fiber Bragg gratings. More than 100 mW of linearly polarized output was achieved from the all-fiber DBR laser with a linewidth less than 3 kHz. The outstanding features of this single-frequency laser also include ultralow relative intensity noise and high wavelength stability. This fiber laser is an excellent seeder for high-power 976 nm narrow-linewidth laser amplifiers that can be used for efficient coherent blue-light generation through frequency doubling. PMID:23073399

  5. A Theory of Laser Induced Nuclear Reaction in Single Atoms

    SciTech Connect

    Faisal, F. H. M.; Donner, C.

    2010-02-02

    An 'electron-bridge' mechanism of nuclear reaction in an atom or ion by ultra-intense laser fields is presented. A preliminary estimate of the intensity dependence of the rate of disintegration reaction of deuteron nucleus in deuterium atom is made for 800 nm laser fields. For intensities below 5x10{sup 21} W/cm{sup 2}, the rate of disintegration by the 'electron-bridge' mechanism is found to be small, but it rises sharply and becomes large already for {approx_equal}10{sup 22} W/cm{sup 2}.

  6. Amplification of ps-pulses from freely triggerable gain-switched laser diodes at 1062 nm and second harmonic generation in periodically poled lithium niobate

    NASA Astrophysics Data System (ADS)

    Schönau, Thomas; Riecke, Sina M.; Lauritsen, Kristian; Erdmann, Rainer

    2011-03-01

    We present a compact frequency-doubled laser source with fundamental wavelength operation at 1062 nm. A freely triggerable seed diode laser delivers sub-100 ps pulses in the picojoule range at variable repetition rates up to 80 MHz. After amplification in a Ytterbium-doped fiber amplifier, the average power exceeds 380mW at 40 MHz, which corresponds to 9.5 nJ pulses and about 75W of peak power. The output beam is then focussed into periodically poled lithium niobate for second harmonic generation (SHG). In this way, green picosecond pulses with an energy of up to 2 nJ at 40MHz are generated. The pulse energy and pulse shape of the second harmonic pulses are systematically studied for various repetition rates, allowing conclusions on the amplifier performance under different operating conditions.

  7. Inversed Vernier effect based single-mode laser emission in coupled microdisks

    PubMed Central

    Li, Meng; Zhang, Nan; Wang, Kaiyang; Li, Jiankai; Xiao, Shumin; Song, Qinghai

    2015-01-01

    Recently, on-chip single-mode laser emissions in coupled microdisks have attracted considerable research attention due to their wide applications. While most of single-mode lasers in coupled microdisks or microrings have been qualitatively explained by either Vernier effect or inversed Vernier effect, none of them have been experimentally confirmed. Here, we studied the mechanism of single-mode laser operation in coupled microdisks. We found that the mode numbers had been significantly reduced to nearly single-mode within a large pumping power range from threshold to gain saturation. The detail laser spectra showed that the largest gain and the first lasing peak were mainly generated by one disk and the laser intensity was proportional to the wavelength detuning of two set of modes. The corresponding theoretical analysis showed that the experimental observations were dominated by internal coupling within one cavity, which was similar to the recently explored inversed Vernier effect in two coupled microrings. We believe our finding will be important for understanding the previous experimental findings and the development of on-chip single-mode laser. PMID:26330218

  8. Bright laser source with high-power single-mode-emitting diode laser stacked array assembly and fiber coupling

    NASA Astrophysics Data System (ADS)

    Forrer, M.; Moser, H.; Gisler, T.; Spinola Durante, G.; Pierer, J.; Bosshard, C.; Krejci, M.; Lichtenstein, N.

    2011-03-01

    Single-mode-emitting high-power diode laser arrays (SM-HPDLA) are available industrially with more than 50 W emission power per bar. Based on this platform an expandable prototype solution is realized for fiber coupling of a stacked array with more than 100 W to an optical fiber with diameter of 200 micron and NA of 0.11. Advanced methods of controlled assembly of micro-optics by infrared laser-soldering have been developed therefore. We present a compact and scalable concept with scalability on 2 internal and 2 external factors. Internal factors are the increasing beam quality and power stability of high-power single-mode-emitting arrays and the improved assembly accuracy for diode bar and micro-optics. External factors are the interlaced coupling of stacked beam emission from the stacked array and the further option to use optimized polarisation coupling with several diode laser stacks.

  9. Single laser pulse compression via strongly coupled stimulated Brillouin scattering in plasma

    NASA Astrophysics Data System (ADS)

    Peng, H.; Wu, Z. H.; Zuo, Y. L.; Zhang, Z. M.; Zhou, K. N.; Su, J. Q.

    2016-07-01

    Laser amplification in plasma, including stimulated Raman scattering amplification and strongly coupled stimulated Brillouin scattering (sc-SBS) amplification, is very promising to generate ultrahigh-power and ultrashort laser pulses. But both are quite complex in experiments: at least three different laser pulses must be prepared; temporal delay and spatial overlap of these three pulses are difficult. We propose a single pulse compression scheme based on sc-SBS in plasma. Only one moderately long laser is applied, the front part of which ionizes the gas to produced plasma, and gets reflected by a plasma mirror at the end of the gas channel. The reflected front quickly depletes the remaining part of the laser by sc-SBS in the self-similar regime. The output laser is much stronger and shorter. This scheme is at first considered theoretically, then validated by using 1D PIC simulations.

  10. Single shot thermometry using laser induced thermal grating

    NASA Astrophysics Data System (ADS)

    Qu, Pubo; Guan, Xiaowei; Zhang, Zhenrong; Wang, Sheng; Li, Guohua; Ye, Jingfeng; Hu, Zhiyun

    2015-05-01

    With the concern of environmental protection and reducing the fossil fuel consumption, combustion processes need to be more efficient and less contaminable. Therefore, the ability to obtain important thermophysical parameters is crucial to combustion research and combustor design. Traditional surveying techniques were difficult to apply in a confined space, especially the physically intrusions of detectors can alter the combustion processes. Laser-based diagnostic techniques, like CARS, SVRS, PLIF and TDLAS, allow the in situ, non-intrusive, spatially and temporally resolved measurements of combustion parameters in hostile environments. We report here a new non-intrusive optical diagnostic technique, based on laser-induced thermal grating. Thermal gratings generated in NO2/N2 binary mixtures, arise from the nonlinear interaction between the medium and the light radiation from the interference of two pulsed, frequency-doubled Nd:YAG lasers (532 nm). This leads to the formation of a dynamic grating through the resonant absorption and the subsequent collisional relaxation. By the temporally resolved detection of a continuous wave, frequency-doubled Nd:YVO4 probe laser beam (671 nm) diffracted by LITG. The temporal behavior of the signal is a function of the local temperature and other properties of gas, various parameters of the target gas can be extracted by analyzing the signal. The accurate singleshot temperature measurements were carried out at different test conditions using a stainless steel pressurized cell, data averaged on 100 laser shots were compared with simultaneously recorded thermocouple data, and the results were consistent with each other. The LITG signal is shown to grow with increasing the gas pressure and is spatially coherent, which makes the LITG thermometry technique a promising candidate in high pressure environments.

  11. "Liquid Knife" to Fabricate Patterning Single-Crystalline Perovskite Microplates toward High-Performance Laser Arrays.

    PubMed

    Feng, Jiangang; Yan, Xiaoxu; Zhang, Yifan; Wang, Xuedong; Wu, Yuchen; Su, Bin; Fu, Hongbin; Jiang, Lei

    2016-05-01

    A facile and effective "liquid knife" is created by controlling the dewetting process of the liquid precursor, yielding patterning single-crystalline perovskite microplates with uniform size, precise positioning, high quality, and low lasing thresholds. The sizes and location of single-crystalline perovskite are controllable, leading to mode-tunable lasing emission and patterned lasers. PMID:27000628

  12. Single-shot single-voxel lactate measurements using FOCI-LASER and a multiple-quantum filter.

    PubMed

    Payne, Geoffrey S; deSouza, Nandita M; Messiou, Christina; Leach, Martin O

    2015-04-01

    Measurement of tissue lactate using (1) H MRS is often confounded by overlap with intense lipid signals at 1.3 ppm. Single-voxel localization using PRESS is also compromised by the large chemical shift displacement between voxels for the 4.1 ppm (-CH) resonance and the 1.3 ppm -CH3 resonance, leading to subvoxels with signals of opposite phase and hence partial signal cancellation. To reduce the chemical shift displacement to negligible proportions, a modified semi-LASER sequence was written ("FOCI-LASER", abbreviated as fLASER) using FOCI pulses to permit high RF bandwidth even with the limited RF amplitude characteristic of clinical MRI scanners. A further modification, MQF-fLASER, includes a selective multiple-quantum filter to detect lactate and reject lipid signals. The sequences were implemented on a Philips 3 T Achieva TX system. In a solution of brain metabolites fLASER lactate signals were 2.7 times those of PRESS. MQF-fLASER lactate was 47% of fLASER (the theoretical maximum is 50%) but still larger than PRESS lactate. In oil, the main 1.3 ppm lipid peak was suppressed to less than 1%. Enhanced suppression was possible using increased gradient durations. The minimum detectable lactate concentration was approximately 0.5 mM. Coherence selection gradients needed to be at the magic angle to avoid large water signals derived from intermolecular multiple-quantum coherences. In pilot patient measurements, lactate peaks were often observed in brain tumours, but not in cervix tumours; lipids were effectively suppressed. In summary, compared with PRESS, the fLASER sequence yields greatly superior sensitivity for direct detection of lactate (and equivalent sensitivity for other metabolites), while the single-voxel single-shot MQF-fLASER sequence surpasses PRESS for lactate detection while eliminating substantial signals from lipids. This sequence will increase the potential for in vivo lactate measurement as a biomarker in targeted anti-cancer treatments as well as

  13. Opto-injection into single living cells by femtosecond near-infrared laser

    NASA Astrophysics Data System (ADS)

    Peng, Cheng

    This dissertation presents a novel technique to deliver membrane impermeable molecules into single living cells with the assistance of femtosecond (fs) near-infrared (NIR) laser pulses. This approach merges ultrafast laser technology with key biological, biomedical, and medical applications, such as gene transfection, gene therapy and drug delivery. This technique promises several major advantages, namely, very high transfection efficiency, high cell survival rate (≈100%) and fully preserved cell viabilities. It is also a promising method to deliver molecules into cells that are difficult or even completely resistant to established physical methods, such as microinjection by glass pipettes, electroporation, and biolistics. In this work, the system for fs NIR opto-injection was designed and built. Successful fs NIR opto-injection has been performed on several cell systems including single mammalian cells (bovine aortic endothelial cells), marine animal eggs (Spisula solidissima oocytes), and human cancer cells (fibrosarcoma HT1080) cultured in a tissue-like environment. The connections between laser parameters and cell responses were explored through further experiments and in-depth analyses, especially the relationship between dye uptake rate and incident laser intensity, and the relationship between pore size created on cell membranes and incident laser intensity. Dye uptake rate of the target cells was observed to depend on incident laser intensity. Pore size was found dependent on incident laser intensity. The conclusion was made that laser-induced breakdown and plasma-induced ablation in cell membrane are the physical principles that govern the process of fs NIR opto-injection.

  14. A single-frequency double-pulse Ho:YLF laser for CO2-lidar

    NASA Astrophysics Data System (ADS)

    Kucirek, P.; Meissner, A.; Eiselt, P.; Höfer, M.; Hoffmann, D.

    2016-03-01

    A single-frequency q-switched Ho:YLF laser oscillator with a bow-tie ring resonator, specifically designed for highspectral stability, is reported. It is pumped with a dedicated Tm:YLF laser at 1.9 μm. The ramp-and-fire method with a DFB-diode laser as a reference is employed for generating single-frequency emission at 2051 nm. The laser is tested with different operating modes, including cw-pumping at different pulse repetition frequencies and gain-switched pumping. The standard deviation of the emission wavelength of the laser pulses is measured with the heterodyne technique at the different operating modes. Its dependence on the single-pass gain in the crystal and on the cavity finesse is investigated. At specific operating points the spectral stability of the laser pulses is 1.5 MHz (rms over 10 s). Under gain-switched pumping with 20% duty cycle and 2 W of average pump power, stable single-frequency pulse pairs with a temporal separation of 580 μs are produced at a repetition rate of 50 Hz. The measured pulse energy is 2 mJ (<2 % rms error on the pulse energy over 10 s) and the measured pulse duration is approx. 20 ns for each of the two pulses in the burst.

  15. Measurement of the emission linewidth of a single-frequency semiconductor laser with a ring fibre interferometer

    SciTech Connect

    Trikshev, A I; Kurkov, Andrei S; Tsvetkov, V B; Pyrkov, Yu N; Paramonov, V N

    2011-07-31

    A simple scanning interferometer is implemented for measuring the emission linewidth of single-frequency semiconductor lasers. The free dispersion region of the interferometer is 28 MHz, the spectral resolution being 470 kHz. (laser spectroscopy)

  16. Laser bandwidth interlock capable of single pulse detection and rejection

    DOEpatents

    Armstrong, James P; Telford, Steven James; Lanning, Rodney Kay; Bayramian, Andrew James

    2012-10-09

    A pulse of laser light is switched out of a pulse train and spatially dispersed into its constituent wavelengths. The pulse is collimated to a suitable size and then diffracted by high groove density multilayer dielectric gratings. This imparts a different angle to each individual wavelength so that, when brought to the far field with a lens, the colors have spread out in a linear arrangement. The distance between wavelengths (resolution) can be tailored for the specific laser and application by altering the number of times the beam strikes the diffraction gratings, the groove density of the gratings and the focal length of the lens. End portions of the linear arrangement are each directed to a respective detector, which converts the signal to a 1 if the level meets a set-point, and a 0 if the level does not. If both detectors produces a 1, then the pulse train is allowed to propagate into an optical system.

  17. Intracavity Microfluidic Laser Device for Single Cell Analysis

    NASA Astrophysics Data System (ADS)

    Gourley, Paul

    2015-03-01

    An intracavity microfluidic laser device has been developed to study bioparticles ranging in size from 50 nm to 20 μm (virons to organelles to whole cells). The versatile device can be operated used in several modes including static or flowing fluids, with or without molecular labels, and microscopic imaging and/or spectroscopy. It enables advantageous new ways to perform analyses of bioparticles for applications including cell biology, detection of disease and pathogens, environmental monitoring, pharmaceuticals, agriculture, and food processing. This talk will briefly summarize the physics of the device including its laser optics, fluid dynamics, and intracavity light interaction with cells. The talk will then focus on results of a study of mitochondria in normal and cancer liver cells. The study examines the transformation of intracellular and isolated mitochondria from the normal to disease state. The results highlight the unique utility of the device to rapidly assess biophysical changes arising from altered biomolecular states of cells and organelles.

  18. Simultaneous ion beam profile scan using a single laser source

    NASA Astrophysics Data System (ADS)

    Liu, Y.; Long, C.; Huang, C.; Dickson, R.; Aleksandrov, A.

    2013-01-01

    We report on the world’s first experiment of a simultaneous profile scan of the hydrogen ion (H-) beam using a laser wire system. The system was developed and brought to operational level of application at the superconducting linac of the Spallation Neutron Source accelerator complex. The laser wire profile scanner is based on a photodetachment process and therefore can be conducted on a 1-MW neutron production H- beam in a nonintrusive manner. The new simultaneous profile scanning system allows one to simultaneously measure profiles of the H- beam at nine different locations of the linac with high speed and accuracy, and therefore provides a unique tool for accelerator tuning and physics study. This paper describes the design, optical system and software platform developments, and measurement results of the simultaneous profile scanning system.

  19. Absorption of a single 500 fs laser pulse at the surface of fused silica: Energy balance and ablation efficiency

    SciTech Connect

    Varkentina, N.; Sanner, N.; Lebugle, M.; Sentis, M.; Utéza, O.

    2013-11-07

    Ablation of fused silica by a single femtosecond laser pulse of 500 fs pulse duration is investigated from the perspective of efficiency of incident photons to remove matter. We measure the reflected and transmitted fractions of the incident pulse energy as a function of fluence, allowing us to recover the evolution of absorption at the material surface. At the ablation threshold fluence, 25% of incident energy is absorbed. At high fluences, this ratio saturates around 70% due to the appearance of a self-triggered plasma mirror (or shielding) effect. By using the energy balance retrieved experimentally and measurements of the ablated volume, we show that the amount of absorbed energy is far above the bonding energy of fused silica at rest and also above the energy barrier to ablate the material under non-equilibrium thermodynamic conditions. Our results emphasize the crucial role of transient plasma properties during the laser pulse and suggest that the major part of the absorbed energy has been used to heat the plasma formed at the surface of the material. A fluence range yielding an efficient and high quality ablation is also defined, which makes the results relevant for femtosecond micromachining processes.

  20. Optical transmission through a polarization preserving single mode optical fiber at two Ar(+) laser wavelengths

    NASA Technical Reports Server (NTRS)

    Tedjojuwono, Ken K.; Hunter, William W., Jr.

    1989-01-01

    The transmission characteristics of two Ar(+) laser wavelengths through a twenty meter Panda type Polarization Preserving Single Mode Optical Fiber (PPSMOF) were measured. The measurements were done with both single and multi-longitudinal mode radiation. In the single longitudinal mode case, a degrading Stimulated Brillouin Scattering (SBS) is observed as a backward scattering loss. By choosing an optimum coupling system and manipulating the input polarization, the threshold of the SBS onset can be raised and the transmission efficiency can be increased.

  1. Performance characteristics of a 1. 5. mu. m single-frequency semiconductor laser with an external waveguide Bragg reflector

    SciTech Connect

    Olsson, N.A.; Henry, C.H.; Kazarinov, R.F.; Lee, H.J.; Orlowsky, K.J.; Johnson, B.H.; Scotti, R.E.; Ackerman, D.A.; Anthony, P.J.

    1988-02-01

    Single-frequency operation of 1.5 ..mu..m semiconductor lasers was obtained by combining a regular Fabry-Perot laser to an external waveguide Bragg reflector. The laser is characterized by very pure single-frequency operation, 1 MHz linewidth, and greatly-reduced frequency chirp under direct modulation. The laser has been tested in 1.7 Gbit/s transmission experiments over 82.5 km of fiber.

  2. Development of a single-longitudinal-mode, high-peak-power, tunable pulsed dye laser

    SciTech Connect

    Black, J.F.; Valentini, J.J. )

    1994-09-01

    A compact, high-peak-power, user-friendly, single-longitudinal-mode (SLM) tunable dye laser has been developed. The device yields [gt]12 mJ pulses of 6 ns duration and [similar to]2.7[times]transform-limited linewidths of [lt]200 MHz. Seamless single-mode tunability of [gt]20 cm[sup [minus]1] is possible without resetting. The dye laser makes efficient use of the pump laser, with [similar to]10% conversion of the 532 nm pump energy to tunable dye power and occupies [lt]4 m[sup 2] (including pump laser and all diagnostics). The linewidth of the device can be switched from [lt]200 MHz SLM operation to [lt]0.5 cm[sup [minus]1] broadband modeless operation by moving one mirror. This allows rapid interchange between high-resolution scanning and a fast survey scan'' mode of operation to isolate the spectral region of interest at low resolution.

  3. In vitro photoacoustic measurement of hemoglobin oxygen saturation using a single pulsed broadband supercontinuum laser source.

    PubMed

    Lee, Changho; Jeon, Mansik; Jeon, Min Yong; Kim, Jeehyun; Kim, Chulhong

    2014-06-20

    We have utilized a single pulsed broadband supercontinuum laser source to photoacoustically sense total hemoglobin concentration (HbT) and oxygen saturation of hemoglobin (SO2) in bloods in vitro. Unlike existing expensive and bulky laser systems typically used for functional photoacoustic imaging (PAI), our laser system is relatively cost-effective and compact. Instead of using two single wavelengths, two wavelength bands were applied to distinguish the concentrations of two different chromophores in the mixture. In addition, we have successfully extracted the total dye concentration and the ratio of the red dye concentration to the total dye concentration in mixed red and blue dye solutions in phantoms. The results indicate that PAI with a cheap and compact fiber based laser source can potentially provide HbT and SO2 in live animals in vivo. PMID:24979418

  4. Single-frequency polarized eye-safe all-fiber laser with peak power over kilowatt

    NASA Astrophysics Data System (ADS)

    Zhang, Xin; Diao, Weifeng; Liu, Yuan; Liu, Jiqiao; Hou, Xia; Chen, Weibiao

    2014-04-01

    An all-fiber, single-frequency, linearly polarized, high peak-power, pulsed laser at 1,540 nm for Doppler wind lidar is presented. This laser is composed of a single-frequency, narrow-linewidth external cavity diode laser, and multistage fiber amplifiers. A peak power of 1.08 kW and a pulse width of 500 ns at 10 kHz repetition rate are achieved, which is the highest peak power with a linewidth of 800 kHz in erbium-doped silica fiber to our knowledge. The beam quality of M 2 < 1.3 and a polarization extinction ratio over 16 dB are obtained. This laser will be employed in a compact long-range coherent Doppler wind lidar.

  5. Generation of ultra-intense single-cycle laser pulses by using photon deceleration

    PubMed Central

    Tsung, F. S.; Ren, C.; Silva, L. O.; Mori, W. B.; Katsouleas, T.

    2002-01-01

    A scheme to generate single-cycle laser pulses is presented based on photon deceleration in underdense plasmas. This robust and tunable process is ideally suited for lasers above critical power because it takes advantage of the relativistic self-focusing of these lasers and the nonlinear features of the plasma wake. The mechanism is demonstrated by particle-in-cell simulations in three and 2½ dimensions, resulting in pulse shortening up to a factor of 4, thus making it feasible to generate few-femtosecond single-cycle pulses in the optical to IR domain with intensities I > 1020 W/cm2 by using present-day laser technology. PMID:11752414

  6. Quantum dash based single section mode locked lasers for photonic integrated circuits.

    PubMed

    Joshi, Siddharth; Calò, Cosimo; Chimot, Nicolas; Radziunas, Mindaugas; Arkhipov, Rostislav; Barbet, Sophie; Accard, Alain; Ramdane, Abderrahim; Lelarge, Francois

    2014-05-01

    We present the first demonstration of an InAs/InP Quantum Dash based single-section frequency comb generator designed for use in photonic integrated circuits (PICs). The laser cavity is closed using a specifically designed Bragg reflector without compromising the mode-locking performance of the self pulsating laser. This enables the integration of single-section mode-locked laser in photonic integrated circuits as on-chip frequency comb generators. We also investigate the relations between cavity modes in such a device and demonstrate how the dispersion of the complex mode frequencies induced by the Bragg grating implies a violation of the equi-distance between the adjacent mode frequencies and, therefore, forbids the locking of the modes in a classical Bragg Device. Finally we integrate such a Bragg Mirror based laser with Semiconductor Optical Amplifier (SOA) to demonstrate the monolithic integration of QDash based low phase noise sources in PICs. PMID:24921823

  7. Coupling of DBR tapered diode laser radiation into a single-mode-fiber at high powers

    NASA Astrophysics Data System (ADS)

    Jedrzejczyk, D.; Asbahr, P.; Pulka, M.; Eppich, B.; Paschke, K.

    2014-03-01

    In this work, we investigate experimentally coupling of diode laser radiation into a single-mode-fiber (SMF) at high optical power. In particular, nearly diffraction-limited, single-frequency continuous wave (CW) radiation around 1064 nm generated by a distributed Bragg reflector (DBR) tapered diode laser is coupled in a bench-top experiment into an SMF with a core diameter of approx. 6 μm. Misalignment tolerances for efficient SMF coupling are determined through two-dimensional coupling efficiency scans, conducted for an attenuated diode laser beam. The coupling efficiency and the laser beam properties behind the SMF are investigated in dependence on the optical power in front of the SMF. A maximum power ex fiber of 3.5 W at a coupling efficiency of 65 % is reached.

  8. Single frequency fiber laser at 2.05 μm based on Ho-doped germanate glass fiber

    NASA Astrophysics Data System (ADS)

    Wu, Jianfeng; Yao, Zhidong; Zong, Jie; Chavez-Pirson, Arturo; Peyghambarian, Nasser; Yu, Jirong

    2009-02-01

    A single frequency fiber laser operating near 2 micron with over 50 mW output power has been demonstrated by using a short piece of newly developed single mode holmium-doped germanate glass fiber. Laser from 2004 nm to 2083 nm was demonstrated from a short Ho-doped fiber laser cavity. A heavily thulium-doped germanate fiber was used as an in-band pump source for the holmium-doped fiber laser. The single frequency fiber laser can be thermally tuned.

  9. Single-step direct laser fabrication of complex shaped microoptical components

    NASA Astrophysics Data System (ADS)

    Žukauskas, Albertas; Tikuišis, Kristupas K.; Ščiuka, Mindaugas; Melninkaitis, Andrius; Gadonas, Roaldas; Reinhardt, Carsten; Malinauskas, Mangirdas

    2012-06-01

    We report on the fabrication of the minimized conventional microoptical components out of the hybrid organic- inorganic SZ2080 and SG4060 photoresins using laser direct writing technique. An ascending laser focus multiscan approach is introduced as a method for the structuring of 2D nanolines. The diameters and heights of the nanolines are comparable to the ones written with the electron beam lithography. Using our proposed laser direct writing approach one can write 3D microstructures with the 2D nanofeatures in a single step procedure. As demonstration of this technology, microlenses with 1D, 2D and circular transmission gratings were fabricated. Additionally, for the rst time, ISO certied laser-induced damage testing was applied to determine the optical breakdown threshold of the SZ2080 photoresin used for the laser direct writing.

  10. Chirp control of a single-mode, good beam quality, zigzag dye laser

    SciTech Connect

    Mandl, A.; Zavriyev, A.; Klimek, D.E.

    1997-03-01

    The authors report a substantial reduction of frequency chirp of a single-mode laser-pumped zigzag dye laser. A linear optical cavity using counterpropagating orthogonally polarized waves was injection-seeded at 568 nm and operated with a laser output of about 1 J. The chirp was controlled by an intracavity Pockels cell that was configured to add optical density at a rate which counterbalanced the decrease in optical density due to dye-solvent heating during the {approximately}1-{micro}s laser pulse. Heterodyne measurements were used to determine that the bandwidth was near the transform limit and chirp rate of {approximately}1 MHz/{micro}s. The beam quality of the laser was measured at 10 Hz as 1.7 XDL.

  11. High power single-longitudinal-mode cyan laser at 500.8 nm

    NASA Astrophysics Data System (ADS)

    Hao, E. J.; Li, T.; Wang, Z. D.

    2012-05-01

    An all-solid-state single-longitudinal-mode (SLM) laser at 500.8 nm with 830 mW output power has been demonstrated for the first time. By using a new resonator for doubly resonant, Nd:GdVO4 and Nd:YAG were pumped by two laser diode arrays coupled by optical fiber, respectively. In the two sub-cavities, SLM wavelengths of 1064 and 946 nm were induced by using the twisted-mode technique and then mixed into SLM 500.8 nm laser with sum-frequency technology. The SLM 500.8 nm laser output of 830 mW was obtained at the incident pump power of 20 W for Nd:GdVO4 and 23 W for Nd:YAG. The experimental results showed that the intracavity sum-frequency mixing by twisted-mode technique is an effective method for SLM 500.8 nm laser.

  12. Ablation and analysis of small cell populations and single cells by consecutive laser pulses

    NASA Astrophysics Data System (ADS)

    Shrestha, Bindesh; Nemes, Peter; Vertes, Akos

    2010-10-01

    Laser ablation of single cells through a sharpened optical fiber is used for the detection of metabolites by laser ablation electrospray ionization (LAESI) mass spectrometry (MS). Ablation of the same Allium cepa epidermal cell by consecutive pulses indicates the rupture of the cell wall by the second shot. Intracellular sucrose heterogeneity is detected by subsequent laser pulses pointing to rupturing the vacuolar membrane by the third exposure. Ion production by bursts of laser pulses shows that the drying of ruptured A. cepa cells occurs in ˜50 s at low pulse rates (10 pulses/s bursts) and significantly faster at high pulse rates (100 pulses/s bursts). These results point to the competing role of cytoplasm ejection and evaporative drying in diminishing the LAESI-MS signal in ˜50 s or 100 laser pulses, whichever occurs first.

  13. Single attosecond pulse generation by nonlinear Thomson scattering in a tightly focused intense laser beam

    SciTech Connect

    Lan Pengfei; Lu Peixiang; Cao Wei

    2006-01-15

    The relativistic nonlinear Thomson scattering of a tightly focused intense laser pulse by an electron is investigated, and the temporal and spectral characters of the radiation are discussed. In a tightly focused laser pulse with an intensity of approximately 10{sup 20} W/cm{sup 2} and a pulse duration of 20 fs, the electron is scattered away from the focus quickly by the ponderomotive force and therefore the radiation emitted at the focus is much higher than that at other regions. As a result, a single ultrashort pulse of 3.8 as is generated and its corresponding spectrum is broadened to 200 orders of the frequency of the driving laser. With increasing the laser intensity, the signal-to-noise of the radiated pulse increases, and the pulse duration decreases. Moreover, the phase behavior of the spectral components and the dependence of the radiated power on the laser intensity are discussed.

  14. Injection chaining of diode-pumped single-frequency ring lasers for free-space communication

    NASA Technical Reports Server (NTRS)

    Cheng, E. A. P.; Kane, T. J.; Wallace, R. W.; Cornwell, D. M., Jr.

    1991-01-01

    A high-power three-stage laser suitable for use in a space communication system has been built. This laser uses three diode-pumped Nd:YAG oscillators coherently combined using the technique of injection chaining. All three oscillators are in one compact and permanently aligned package, and are actively frequency locked to provide CW single frequency output. The three stages provide the redundancy desirable for space communications.

  15. Preliminary Investigation of Keyhole Phenomena during Single Layer Fabrication in Laser Additive Manufacturing of Stainless Steel

    NASA Astrophysics Data System (ADS)

    Matilainen, Ville-Pekka; Piili, Heidi; Salminen, Antti; Nyrhilä, Olli

    Laser additive manufacturing (LAM) is a fabrication technology that enables production of complex parts from metallic materials with mechanical properties comparable to conventionally manufactured parts. In the LAM process, parts are manufactured by melting metallic powder layer-by-layer with a laser beam. This manufacturing technology is nowadays called powder bed fusion (PBF) according to the ASTM F2792-12a standard. This strategy involves several different independent and dependent thermal cycles, all of which have an influence on the final properties of the manufactured part. The quality of PBF parts depends strongly on the characteristics of each single laser-melted track and each single layer. This study consequently concentrates on investigating the effects of process parameters such as laser power on single track and layer formation and laser-material interaction phenomena occurring during the PBF process. Experimental tests were done with two different machines: a modified research machine based on an EOS EOSINT M-series system and an EOS EOSINT M280 system. The material used was EOS stainless steel 17-4 PH. Process monitoring was done with an active illuminated high speed camera system. After microscopy analysis, it was concluded that a keyhole can form during laser additive manufacturing of stainless steel. It was noted that heat input has an important effect on the likelihood of keyhole formation. The threshold intensity value for keyhole formation of 106 W/cm2 was exceeded in all manufactured single tracks. Laser interaction time was found to have an effect on penetration depth and keyhole formation, since the penetration depth increased with increased laser interaction time. It was also concluded that active illuminated high speed camera systems are suitable for monitoring of the manufacturing process and facilitate process control.

  16. Single-frequency, fully integrated, miniature DPSS laser based on monolithic resonator

    NASA Astrophysics Data System (ADS)

    Dudzik, G.; Sotor, J.; Krzempek, K.; Soboń, G.; Abramski, K. M.

    2014-02-01

    We present a single frequency, stable, narrow linewidth, miniature laser sources operating at 532 nm (or 1064 nm) based on a monolithic resonators. Such resonators utilize birefringent filters formed by YVO4 beam displacer and KTP or YVO4 crystals to force single frequency operation at 532 nm or 1064 nm, respectively. In both configurations Nd:YVO4 gain crystal is used. The resonators dimensions are 1x1x10.5 mm3 and 1x1x8.5 mm3 for green and infrared configurations, respectively. Presented laser devices, with total dimensions of 40x52x120 mm3, are fully equipped with driving electronics, pump diode, optical and mechanical components. The highly integrated (36x15x65 mm3) low noise driving electronics with implemented digital PID controller was designed. It provides pump current and resonator temperature stability of ±30 μA@650 mA and ±0,003ºC, respectively. The laser parameters can be set and monitored via the USB interface by external application. The developed laser construction is universal. Hence, the other wavelengths can be obtained only by replacing the monolithic resonator. The optical output powers in single frequency regime was at the level of 42 mW@532 nm and 0.5 W@1064 nm with the long-term fluctuations of ±0.85 %. The linewidth and the passive frequency stability under the free running conditions were Δν < 100 kHz and 3ṡ10-9@1 s integration time, respectively. The total electrical power supply consumption of laser module was only 4 W. Presented compact, single frequency laser operating at 532 nm and 1064 nm may be used as an excellent source for laser vibrometry, interferometry or seed laser for fiber amplifiers.

  17. Single Molecule Analysis of Laser Localized Interstrand Crosslinks

    PubMed Central

    Huang, Jing; Gali, Himabindu; Paramasivam, Manikandan; Muniandy, Parameswary; Gichimu, Julia; Bellani, Marina A.; Seidman, Michael M.

    2016-01-01

    DNA interstrand crosslinks (ICLs) block unwinding of the double helix, and have always been regarded as major challenges to replication and transcription. Compounds that form these lesions are very toxic and are frequently used in cancer chemotherapy. We have developed two strategies, both based on immunofluorescence (IF), for studying cellular responses to ICLs. The basis of each is psoralen, a photoactive (by long wave ultraviolet light, UVA) DNA crosslinking agent, to which we have linked an antigen tag. In the one approach, we have taken advantage of DNA fiber and immuno-quantum dot technologies for visualizing the encounter of replication forks with ICLs induced by exposure to UVA lamps. In the other, psoralen ICLs are introduced into nuclei in live cells in regions of interest defined by a UVA laser. The antigen tag can be displayed by conventional IF, as can the recruitment and accumulation of DNA damage response proteins to the laser localized ICLs. However, substantial difference between the technologies creates considerable uncertainty as to whether conclusions from one approach are applicable to those of the other. In this report, we have employed the fiber/quantum dot methodology to determine lesion density and spacing on individual DNA molecules carrying laser localized ICLs. We have performed the same measurements on DNA fibers with ICLs induced by exposure of psoralen to UVA lamps. Remarkably, we find little difference in the adduct distribution on fibers prepared from cells exposed to the different treatment protocols. Furthermore, there is considerable similarity in patterns of replication in the vicinity of the ICLs introduced by the two techniques. PMID:27242893

  18. Continuously-tunable single-frequency semiconductor lasers

    SciTech Connect

    Coldren, L.A.; Corzine, S.W.

    1987-06-01

    The design of ''ideal'' tunable laser sources that are capable of being continuously turned over the entire gain bandwith with maximum mode suppression are considered. It is shown that certain extended-cavity three-section configurations satisfy the necessary conditions for such electronic tunability, but that phase shifters with advanced capabilities are necessary. It is also shown that it is not possible to achieve this goal in a two-section configuration, although continuous tuning up to about one longitudinal mode spacing should be possible with some compromise in spurious mode suppression.

  19. AlxGa1-xAs Single-Quantum-Well Surface-Emitting Lasers

    NASA Technical Reports Server (NTRS)

    Kim, Jae H.

    1992-01-01

    Surface-emitting solid-state laser contains edge-emitting Al0.08Ga0.92As single-quantum-well (SQW) active layer sandwiched between graded-index-of-refraction separate-confinement-heterostructure (GRINSCH) layers of AlxGa1-xAs, includes etched 90 degree mirrors and 45 degree facets to direct edge-emitted beam perpendicular to top surface. Laser resembles those described in "Pseudomorphic-InxGa1-xAs Surface-Emitting Lasers" (NPO-18243). Suitable for incorporation into optoelectronic integrated circuits for photonic computing; e.g., optoelectronic neural networks.

  20. Process of stopping atoms with the Zeeman tuning technique with a single laser

    SciTech Connect

    Firmino, M.E.; Faria Leite, C.A.; Zilio, S.C.; Bagnato, V.S. )

    1990-04-01

    We report an observation of atoms stopped by laser light in an experiment using the Zeeman tuning technique. In contrast to previous experiments using the same technique, we are able to stop the atoms outside the slower solenoid using a single laser. The deceleration process is monitored through the measurement of the fluorescence along the deceleration path in such a way that the slower laser is also used for diagnosis. This technique also permits the realization of a few interesting observations on the process such as the position where the atoms stop scattering photons.

  1. Narrow linewidth single-mode semiconductor laser development for coherent detection lidar

    NASA Technical Reports Server (NTRS)

    Mansour, Kamjou; Ksendzov, Alexander; Menzies, Robert T.; Maker, Paul D.; Muller, Richard E.; Manfra, M. J.; Turner, George W.

    2003-01-01

    High power, tunable, single mode, narrow linewidth semiconductor lasers in the 2.05-(micro)m wavelength region are needed to develop semiconductor laser reference oscillators for optical remote sensing from Earth orbit. 2.05-I1/4m narrow linewidth monolithic distributed feedback (DFB) and distributed Bragg reflector (DBR) with the external grating ridge waveguide lasers fabricated from epitaxially grown InGaAs/InGaAsP/InP and in InGaAsSb/AlGaAsSb/GaSb heterostructures are reported.

  2. Efficient 0.9-{mu}m neodymium-doped single-mode fibre laser

    SciTech Connect

    Bufetov, Igor' A; Dudin, V V; Shubin, Aleksei V; Senatorov, A K; Dianov, Evgenii M; Grudinin, A B; Goncharov, S E; Zalevskii, I D; Gur'yanov, A N; Yashkov, M V; Umnikov, A A; Vechkanov, N N

    2003-12-31

    An efficient cw single-mode double-clad Nd{sup 3+}-doped fibre laser is developed which operates at room temperature in a quasi-three level scheme on the 925-nm {sup 4}F{sub 3/2} - {sup 4}I{sub 9/2} transition upon diode pump at 805 nm. The gain in the laser resonator at 1.06 {mu}m is strongly suppressed due to a proper choice of the refractive index profile in the fibre core. The laser output power above 0.5 W is obtained with the slope efficiency exceeding 35 %. (letters)

  3. Pure, single crystal Ge nanodots formed using a sandwich structure via pulsed UV excimer laser annealing.

    PubMed

    Liao, Ting-Wei; Chen, Hung-Ming; Shen, Kuan-Yuan; Kuan, Chieh-Hsiung

    2015-04-24

    In this paper, a sandwich structure comprising a SiO2 capping layer, amorphous Germanium (a-Ge) nanodots (NDs), and a pit-patterned Silicon (Si) substrate is developed, which is then annealed by utilizing a pulsed ultraviolet excimer laser in order to fabricate an array of pure, single crystal Ge NDs at room temperature. A wide bandgap SiO2 capping layer is used as a transparent thermally isolated layer to prevent thermal loss and Si-Ge intermixing. The two-dimensional pit-patterned Si substrate is designed to confine the absorbed laser energy, reduce the melting point, and block the surface migration of the Ge. After optimizing the laser radiation parameters such that the laser energy density is 200 mJ cm(-2), the laser annealing period is 10 s, and the number of laser shots is 10, pure, single crystal Ge NDs that have both a regular arrangement and a uniform size distribution are obtained in the pits of the Si substrates. The Raman spectrum shows a highly symmetric Ge transversal optical peak with a full width at half maximum of 4.2 cm(-1) at 300.7 cm(-1), which is close to that of the original Ge wafer. In addition, the high-resolution transmission electron microscopy image for the Ge NDs and the corresponding selected area electron diffraction pattern shows a clear single crystalline structure without any impurities. PMID:25815515

  4. Pure, single crystal Ge nanodots formed using a sandwich structure via pulsed UV excimer laser annealing

    NASA Astrophysics Data System (ADS)

    Liao, Ting-Wei; Chen, Hung-Ming; Shen, Kuan-Yuan; Kuan, Chieh-Hsiung

    2015-04-01

    In this paper, a sandwich structure comprising a SiO2 capping layer, amorphous Germanium (a-Ge) nanodots (NDs), and a pit-patterned Silicon (Si) substrate is developed, which is then annealed by utilizing a pulsed ultraviolet excimer laser in order to fabricate an array of pure, single crystal Ge NDs at room temperature. A wide bandgap SiO2 capping layer is used as a transparent thermally isolated layer to prevent thermal loss and Si-Ge intermixing. The two-dimensional pit-patterned Si substrate is designed to confine the absorbed laser energy, reduce the melting point, and block the surface migration of the Ge. After optimizing the laser radiation parameters such that the laser energy density is 200 mJ cm-2, the laser annealing period is 10 s, and the number of laser shots is 10, pure, single crystal Ge NDs that have both a regular arrangement and a uniform size distribution are obtained in the pits of the Si substrates. The Raman spectrum shows a highly symmetric Ge transversal optical peak with a full width at half maximum of 4.2 cm-1 at 300.7 cm-1, which is close to that of the original Ge wafer. In addition, the high-resolution transmission electron microscopy image for the Ge NDs and the corresponding selected area electron diffraction pattern shows a clear single crystalline structure without any impurities.

  5. Single-frequency gain-switched Ho-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Geng, Jihong; Wang, Q.; Luo, T.; Case, B.; Jiang, S.; Amzajerdian, Farzin; Yu, Jirong

    2012-10-01

    We demonstrate a single-frequency gain-switched Ho-doped fiber laser based on heavily doped silicate glass fiber fabricated in house. A Q-switched Tm-doped fiber laser at 1.95μm was used to gain-switch the Ho-doped fiber laser via in-band pumping. Output power of the single-frequency gain-switched pulses has been amplified in a cladding-pumped Tm-Ho-codoped fiber amplifier with 1.2m active fiber pumped at 803nm. Two different nonlinear effects, i.e., modulation instability and stimulated Brillouin scattering, could be seen in the 10μm-core fiber amplifier when the peak power exceeds 3kW. The single-frequency gain-switched fiber laser was operated at 2.05μm, a popular laser wavelength for Doppler lidar application. This is the first demonstration of this kind of fiber laser.

  6. Graphene based widely-tunable and singly-polarized pulse generation with random fiber lasers

    PubMed Central

    Yao, B. C.; Rao, Y. J.; Wang, Z. N.; Wu, Y.; Zhou, J. H.; Wu, H.; Fan, M. Q.; Cao, X. L.; Zhang, W. L.; Chen, Y. F.; Li, Y. R.; Churkin, D.; Turitsyn, S.; Wong, C. W.

    2015-01-01

    Pulse generation often requires a stabilized cavity and its corresponding mode structure for initial phase-locking. Contrastingly, modeless cavity-free random lasers provide new possibilities for high quantum efficiency lasing that could potentially be widely tunable spectrally and temporally. Pulse generation in random lasers, however, has remained elusive since the discovery of modeless gain lasing. Here we report coherent pulse generation with modeless random lasers based on the unique polarization selectivity and broadband saturable absorption of monolayer graphene. Simultaneous temporal compression of cavity-free pulses are observed with such a polarization modulation, along with a broadly-tunable pulsewidth across two orders of magnitude down to 900 ps, a broadly-tunable repetition rate across three orders of magnitude up to 3 MHz, and a singly-polarized pulse train at 41 dB extinction ratio, about an order of magnitude larger than conventional pulsed fiber lasers. Moreover, our graphene-based pulse formation also demonstrates robust pulse-to-pulse stability and wide-wavelength operation due to the cavity-less feature. Such a graphene-based architecture not only provides a tunable pulsed random laser for fiber-optic sensing, speckle-free imaging, and laser-material processing, but also a new way for the non-random CW fiber lasers to generate widely tunable and singly-polarized pulses. PMID:26687730

  7. Single mode, short cavity, Pb-salt diode lasers operating in the 5, 10, and 30-microns spectral regions

    NASA Technical Reports Server (NTRS)

    Linden, K. J.

    1985-01-01

    Pb-salt diode lasers are being used as frequency-tunable infrared sources in high resolution spectroscopy and heterodyne detection applications. Recent advances in short cavity, stripe-geometry laser configurations have led to significant increases in maximum CW operating temperature, single mode operation, and increased single mode tuning range. This paper describes short cavity, stripe geometry lasers operating in the 5, 10, and 30-microns spectral regions, with single mode tuning ranges of over 6/cm.

  8. Single frequency high-peak-power fiber laser by suppression of SBS

    NASA Astrophysics Data System (ADS)

    Wang, Shiwei; Zheng, Wanguo; Deng, Ying; Yan, Shuo; Xu, Jianqiu; Tang, Yulong

    2015-08-01

    We report a single frequency Yb-doped fiber laser with a high peak power at the wavelength of 1064 nm. The laser consists of a single-frequency diode seed and two amplifier stages. In the pre-amplifier, double-pass amplification is adopted by integrating a specially designed fiber Bragg grating to filter out amplified spontaneous emission and achieve high signal-to-noise ratio. The stimulation Brillouin scattering is suppressed by the linewidth broadening due to the cross phase modulation between the signals propagated in the backward and forward directions. In the boost amplifier, a disaster area of the stimulated Brillouin scattering is found and is stepped over by management of both the signal and pump power. The laser generates the peak power of 2.2 kW in single-mode linearly polarized output with a linewidth of around 230 MHz.

  9. On-chip interference of single photons from an embedded quantum dot and an external laser

    NASA Astrophysics Data System (ADS)

    Prtljaga, N.; Bentham, C.; O'Hara, J.; Royall, B.; Clarke, E.; Wilson, L. R.; Skolnick, M. S.; Fox, A. M.

    2016-06-01

    In this work, we demonstrate the on-chip two-photon interference between single photons emitted by a single self-assembled InGaAs quantum dot and an external laser. The quantum dot is embedded within one arm of an air-clad directional coupler which acts as a beam-splitter for incoming light. Photons originating from an attenuated external laser are coupled to the second arm of the beam-splitter and then combined with the quantum dot photons, giving rise to two-photon quantum interference between dissimilar sources. We verify the occurrence of on-chip Hong-Ou-Mandel interference by cross-correlating the optical signal from the separate output ports of the directional coupler. This experimental approach allows us to use a classical light source (laser) to assess in a single step the overall device performance in the quantum regime and probe quantum dot photon indistinguishability on application realistic time scales.

  10. Dynamics of optical breakdown in air induced by single and double nanosecond laser pulses

    SciTech Connect

    Mahdieh, Mohammad Hossein Akbari Jafarabadi, Marzieh

    2015-12-15

    In this paper, an optical breakdown in air induced by single and double nanosecond laser pulses was studied. A high power Nd:YAG laser beam was used for producing optical breakdown plasma in the air. The dynamics of breakdown plasma were studied using an optical probe beam. A portion of the laser beam was used, as the probe beam and was aligned to propagate (perpendicular to the pump beam) through the breakdown region. The transmission of the probe beam (through the breakdown region) was temporally measured for both single and double pulse irradiations. The results were used to describe the evolution of the induced plasma in both conditions. These results show that the plasma formation time and its absorptivity are strongly dependent on the single or double pulse configurations.

  11. Laser-Heated Floating Zone Production of Single-Crystal Fibers

    NASA Technical Reports Server (NTRS)

    Ritzert, Frank; Westfall, Leonard

    1996-01-01

    This report describes how a laser-heated floating zone apparatus can be used to investigate single-crystal fibers of various compositions. A feedrod with a stoichiometric composition of high-purity powders was connected to a pedestal and fed into a laser scan where it combined with a single-crystal fiber seed. A molten zone was formed at this junction. As the feedrod was continuously fed into the laser scan, a single-crystal fiber of a prescribed orientation was withdrawn from the melt. The resultant fibers, whose diameters ranged from 100 to 250 gm, could then be evaluated on the basis of their growth behavior, physical properties, mechanical properties, and fiber perfection.

  12. Single linearly polarized, widely and freely tunable two wavelengths Yb3+-doped fiber laser

    NASA Astrophysics Data System (ADS)

    Liu, Dongfeng; Wang, Chinhua

    2010-01-01

    We report a novel single linearly polarized, widely, freely and continuously tunable two wavelengths Yb3+-doped fiber laser. The laser generates stable arbitrary two wavelengths output between 1003.1 and 1080.7 nm peak wavelengths simultaneously with a 346.0 mW CW power by using polarization beam splitting (PBS) for separation of two wavelengths. Each lasing line shows a single polarization with a polarization extinction ratio of >20 dB under different pump levels. The central and the interval of the two wavelengths can be tuned smoothly and independently in the entire gain region of >70 nm of PM Yb3+-doped single mode fiber. Strongly enhanced polarization-hole burning (PHB) phenomena in polarization maintain (PM) Yb3+-doped fiber was observed in the tunable two wavelengths Yb3+-doped fiber laser.

  13. Dynamics of optical breakdown in air induced by single and double nanosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Mahdieh, Mohammad Hossein; Akbari Jafarabadi, Marzieh

    2015-12-01

    In this paper, an optical breakdown in air induced by single and double nanosecond laser pulses was studied. A high power Nd:YAG laser beam was used for producing optical breakdown plasma in the air. The dynamics of breakdown plasma were studied using an optical probe beam. A portion of the laser beam was used, as the probe beam and was aligned to propagate (perpendicular to the pump beam) through the breakdown region. The transmission of the probe beam (through the breakdown region) was temporally measured for both single and double pulse irradiations. The results were used to describe the evolution of the induced plasma in both conditions. These results show that the plasma formation time and its absorptivity are strongly dependent on the single or double pulse configurations.

  14. Laser Capture and Single Cell Genotyping from Frozen Tissue Sections.

    PubMed

    Kroneis, Thomas; Ye, Jody; Gillespie, Kathleen

    2016-01-01

    There is an increasing requirement for genetic analysis of individual cells from tissue sections. This is particularly the case for analysis of tumor cells but is also a requirement for analysis of cells in pancreas from individuals with type 1 diabetes where there is evidence of viral infection or in the analysis of chimerism in pancreas; either post-transplant or as a result of feto-maternal cell transfer.This protocol describes a strategy to isolate cells using laser microdissection and to run a 17plex PCR to discriminate between cells of haplo-identical origin (i.e., fetal and maternal cells) in pancreas tissue but other robust DNA tests could be used. In short, snap-frozen tissues are cryo-sectioned and mounted onto membrane-coated slides. Target cells are harvested from the tissue sections by laser microdissection and pressure catapulting (LMPC) prior to DNA profiling. This is based on amplification of highly repetitive yet stably inherited loci (short tandem repeats, STR) as well as the amelogenin locus for sex determination and separation of PCR products by capillary electrophoresis. PMID:26659805

  15. Studies of single-mode injection lasers and of quaternary materials. Volume 1: Single-mode constricted double-heterojunction AlGaAs diode lasers

    NASA Technical Reports Server (NTRS)

    Botez, D.

    1982-01-01

    Constricted double-heterojunction (CDH) lasers are presented as the class of single-mode nonplanar-substrate devices for which the lasing cavity is on the least resistive electrical path between the contact and the substrate. Various types of CDH structures are considered under three general topics: liquid-phase epitaxy over channeled substrates, lateral mode control, and current control in nonplanar-substrate devices. Ridge-guide CDH lasers have positive-index lateral-mode confinement and provide: single-mode CW operation to 7 mW/facet at room temperature and to 3 mW/facet at 150 C; light-current characteristics with second-harmonic distortion as low as -57 dB below the fundamental level; threshold-current temperature coefficients, as high as 375 C (pulsed) and 310 C (CW); constant external differential quantum efficiency to 100 C; and lasing operation to 170 C CW and 280 C pulsed. Semileakyguide CDH lasers have an asymmetric leaky cavity for lateral-mode confinement and provide single-mode operation to 15 to 20 mW/facet CW and to 50 mW/facet at 50% duty cycle. Modulation characteristics and preliminary reliability data are discussed.

  16. Characteristics of a laser triggered spark gap using air, Ar, CH4, H2, He, N2, SF6, and Xe

    NASA Astrophysics Data System (ADS)

    Kimura, W. D.; Kushner, M. J.; Seamans, J. F.

    1988-03-01

    A KrF discharge laser (248 nm) has been used to laser trigger, by volume preionization, a spark gap switch (38-65 kV, >10 kA, 100 ns pulse duration) filled with 20 different gas mixtures using various combinations of air, Ar, CH4, H2, He, N2 SF6, and Xe. A pulsed laser interferometer is used to probe the spark column. Characteristics studied include the internal structure of the column, the arc expansion rate, and evidence of any photoionization precursor effect. Our results show that the rate of arc expansion varies depending on the average molecular weight of the mixtures. In this experiment, pure H2 has the highest rate (≊9.5×105 cm/s) and air has one of the lowest (≊7×105 cm/s) for the same hold-off voltage. A computer model of the spark column formation is able to predict most of the structure observed in the arcs, including the effect of mixing gases with widely different molecular weights. The work suggests that, under proper circumstances, the spark gap switch performance may be improved by using gases lighter than conventional switch gases such as SF6.

  17. Single-frequency blue light generation by single-pass sum-frequency generation in a coupled ring cavity tapered laser

    NASA Astrophysics Data System (ADS)

    Bjarlin Jensen, Ole; Michael Petersen, Paul

    2013-09-01

    A generic approach for generation of tunable single frequency light is presented. 340 mW of near diffraction limited, single-frequency, and tunable blue light around 459 nm is generated by sum-frequency generation (SFG) between two tunable tapered diode lasers. One diode laser is operated in a ring cavity and another tapered diode laser is single-passed through a nonlinear crystal which is contained in the coupled ring cavity. Using this method, the single-pass conversion efficiency is more than 25%. In contrast to SFG in an external cavity, the system is entirely self-stabilized with no electronic locking.

  18. Efficient single-frequency fiber lasers with novel photosensitive Er/Yb optical fibers.

    PubMed

    Dong, L; Loh, W H; Caplen, J E; Minelly, J D; Hsu, K; Reekie, L

    1997-05-15

    Boron- and germanium-doped highly photosensitive cladding is used in a novel design to achieve photosensitive Er/Yb-doped fibers, permitting short, strong gratings (length approximately 1 cm, reflectivity >99%) to be written without hydrogenation. The high absorption at 980 nm in Er/Yb fibers permits efficient pump absorption over a short device length, which is ideal for achieving highly efficient single-frequency fiber lasers. Both single-frequency Bragg-grating reflector and distributed-feedback lasers with slope efficiencies of 25% with respect to launched pump power have been realized in such fibers. PMID:18185631

  19. A single beam near-field laser trap for optical stretching, folding and rotation of erythrocytes

    NASA Astrophysics Data System (ADS)

    Gu, Min; Kuriakose, Smitha; Gan, Xiaosong

    2007-02-01

    To understand the fundamental mechanical and viscoelastic properties of RBCs, one needs laser tweezers in which cells can not only be trapped, but also be stretched, folded, and rotated. Stretching, folding and rotating an RBC is particularly important in order to reveal the shear elasticity of the RBC membrane. Here we show a single beam near-field laser trapping technique under focused evanescent wave illumination for optical stretching, folding and rotation of a single RBC. This multifunctional manipulation method will provide a new platform for measuring cell properties such as the membrane elasticity, viscoelasticity and deformability.

  20. High average power quasi-CW single-mode green and UV fiber lasers

    NASA Astrophysics Data System (ADS)

    Avdokhin, Alexey; Gapontsev, Valentin; Kadwani, Pankaj; Vaupel, Andreas; Samartsev, Igor; Platonov, Nicholai; Yusim, Alex; Myasnikov, Daniil

    2015-02-01

    Kilowatt-level narrow-linewidth SM ytterbium fiber laser operating in high-repetition-rate QCW regime was used to obtain 700 W average power at 532 nm with single-mode beam quality and wall-plug efficiency of over 23 %. To the best of our knowledge, this is ~60 % higher power than previously reported for single-mode green lasers based on other platforms, and also is ~30 % increase comparing to the previous result obtained by our group on the base of similar fiber laser platform. We have also experimentally proved that the same type of fiber laser can be used for generating of world-record levels of power at other wavelengths of visible and UV spectral ranges by employing cascaded non-linear frequency conversion. Thus, utilizing frequency tripling in 2 LBO crystals, we achieved over 160 W average power of nearly single-mode UV light at 355 nm with THG efficiency of more than 25 %. As far as we know, this is the highest output power ever reported for UV laser with nearly diffraction limited beam quality. We also conducted some preliminary experiments to demonstrate suitability of our approach for generating longer wavelengths of the visible spectrum. By pre-shifting fundamental emission wavelength in fiber Raman converter, followed by frequency doubling in NCPM LBO, we obtained average powers of 36 W at 589 nm and 27 W at 615 nm. These proof-of-concept experiments were performed with low-power pump laser and were not fully optimized with respect to frequency conversion. Our analysis indicates that employing kW-level QCW ytterbium laser with optimized SRS and SHG converters we can achieve hundreds of Watts of average power in red and orange color with single-mode beam quality.

  1. Single-mode Fabry-Perot laser with deeply etched slanted double trenches

    NASA Astrophysics Data System (ADS)

    Li, Xun; Zhu, Zhongshu; Xi, Yanping; Han, Lin; Ke, Cheng; Pan, Yue; Huang, Weiping

    2015-08-01

    This work proposed and demonstrated a single-mode Fabry-Perot (FP) laser structure with a pair of deeply etched slanted trenches inside the cavity. We implemented the proposed mode selection scheme in conventional 1310 nm InAlGaAs/InP strained-layer multiple-quantum-well ridge waveguide FP laser diodes and obtained single-mode operation with a side-mode suppression ratio (SMSR) as high as 35 dB . The single-mode yield was approximately 55%, and other device performance measures such as the threshold and the slope efficiency were not greatly affected. Additionally, temperature cycling and aging tests show no exceptional disadvantages when compared with the performance of conventional FP lasers. Fiber-optic transmission tests show that the proposed device can send directly modulated 2.5 Gbps and 6.25 Gbps optical signals for distances of over 50 km in standard single-mode fiber. Thus, as a cost-effective solution, this device is promising as a replacement for conventional distributed feedback laser diodes in specific applications where single-mode operation is indispensable but precise control of the lasing wavelength and/or very high SMSR (e.g., > 40 dB ) are not required.

  2. Tree Height Growth Measurement with Single-Scan Airborne, Static Terrestrial and Mobile Laser Scanning

    PubMed Central

    Lin, Yi; Hyyppä, Juha; Kukko, Antero; Jaakkola, Anttoni; Kaartinen, Harri

    2012-01-01

    This study explores the feasibility of applying single-scan airborne, static terrestrial and mobile laser scanning for improving the accuracy of tree height growth measurement. Specifically, compared to the traditional works on forest growth inventory with airborne laser scanning, two issues are regarded: “Can the new technique characterize the height growth for each individual tree?” and “Can this technique refine the minimum growth-discernable temporal interval further?” To solve these two puzzles, the sampling principles of the three laser scanning modes were first examined, and their error sources against the task of tree-top capturing were also analyzed. Next, the three-year growths of 58 Nordic maple trees (Crimson King) for test were intermittently surveyed with one type of laser scanning each time and then analyzed by statistics. The evaluations show that the height growth of each individual tree still cannot be reliably characterized even by single-scan terrestrial laser scanning, and statistical analysis is necessary in this scenario. After Gaussian regression, it is found that the minimum temporal interval with distinguishable tree height growths can be refined into one month based on terrestrial laser scanning, far better than the two years deduced in the previous works based on airborne laser scanning. The associated mean growth was detected to be about 0.12 m. Moreover, the parameter of tree height generally under-estimated by airborne and even mobile laser scanning can be relatively revised by means of introducing static terrestrial laser scanning data. Overall, the effectiveness of the proposed technique is primarily validated. PMID:23112743

  3. Numerical study of nanosecond laser interactions with micro-sized single droplets and sprays of xenon

    SciTech Connect

    Auguste, T.; Gaufridy de Dortan, F. de; Ceccotti, T.; Hergott, J. F.; Sublemontier, O.; Descamps, D.; Schmidt, M.

    2007-02-15

    We present a thorough numerical study on interactions of a nanosecond laser with micro-sized xenon droplets. We developed a code which allows simulation of laser interactions with a single droplet as well as a spray. We give a detailed description of the code, and we present results on the dynamics of a microplasma produced by irradiation of a single xenon droplet with a laser focused at peak vacuum intensity in the 5x10{sup 10}-5x10{sup 12} W/cm{sup 2} range. We find that the heating of the plasma depends dramatically on the laser parameters (duration, pulse shape, and intensity) on one hand, and on the droplet diameter on the other. We also present results obtained with a spray which show that the dynamics of the microplasmas is very sensitive to the position of the droplets in the interaction volume. The predictions of our model agree well with recent experimental observations performed on laser-produced plasma sources for extreme ultraviolet lithography. In particular, the postprocessing of our data with a sophisticated atomic physics code has allowed us to reproduce quite well the spectrum emitted in the extreme ultraviolet range by a xenon plasma generated by laser irradiation of a spray of droplets.

  4. Surface wave measurements using a single continuously scanning laser Doppler vibrometer: application to elastography.

    PubMed

    Salman, Muhammad; Sabra, Karim G

    2013-03-01

    A continuous scanning laser Doppler vibrometry (CSLDV) obtained sweeping a single laser beam along a periodic scan pattern allows measuring surface vibrations at many points simultaneously by demultiplexing the CSLDV signal. This known method fundamentally differs from conventional scanning laser vibrometry techniques in which the laser beam is kept at a fixed point during each measurement and then moved to a new position prior to the next measurement. This article demonstrates the use of a CSLDV for measuring in a non-contact fashion the velocity of low-frequency surface waves (f < 100 Hz) propagating over soft materials, namely here gel surfaces-mimicking human body soft tissues-and skeletal muscles, to develop an affordable and noninvasive elastography modality. The CSLDV vibration measurements obtained with a single laser beam, linearly scanned over the test surface at 200 Hz over lengths up to 6 cm, were validated using an array of three fixed laser Doppler vibrometers distributed along the same scan line. Furthermore, this CSLDV setup was used to measure the increase in surface wave velocity over the biceps brachii muscle which was directly correlated to the actual stiffening of the biceps occurring while a subject was performing voluntary contractions at an increasing level. PMID:23463997

  5. Single step high-speed printing of continuous silver lines by laser-induced forward transfer

    NASA Astrophysics Data System (ADS)

    Puerto, D.; Biver, E.; Alloncle, A.-P.; Delaporte, Ph.

    2016-06-01

    The development of high-speed ink printing process by Laser-Induced Forward Transfer (LIFT) is of great interest for the printing community. To address the problems and the limitations of this process that have been previously identified, we have performed an experimental study on laser micro-printing of silver nanoparticle inks by LIFT and demonstrated for the first time the printing of continuous conductive lines in a single pass at velocities of 17 m/s using a 1 MHz repetition rate laser. We investigated the printing process by means of a time-resolved imaging technique to visualize the ejection dynamics of single and adjacent jets. The control of the donor film properties is of prime importance to achieve single step printing of continuous lines at high velocities. We use a 30 ps pulse duration laser with a wavelength of 343 nm and a repetition rate from 0.2 to 1 MHz. A galvanometric mirror head controls the distance between two consecutives jets by scanning the focused beam along an ink-coated donor substrate at different velocities. Droplets and lines of silver inks are laser-printed on glass and PET flexible substrates and we characterized their morphological quality by atomic force microscope (AFM) and optical microscope.

  6. Broadband Single-Shot Electron Spectrometer for GeV-Class Laser Plasma Based Accelerators

    SciTech Connect

    Nakamura, K.; Wan, W.; Ybarrolaza, N.; Syversrud, D.; Wallig, J.; Leemans, W.P.

    2008-05-01

    Laser-plasma-based accelerators can provide electrons over a broad energy range and/or with large momentum spread. The electron beam energy distribution can be controlled via accurate control of laser and plasma properties, and beams with energies ranging from'0.5 to 1000 MeV have been observed. Measuring these energy distributions in a single shot requires the use of a diagnostic with large momentum acceptance and, ideally, sufficient resolution to accurately measure energy spread in the case of narrow energy spread. Such a broadband single-shot electron magnetic spectrometer for GeV-class laser-plasma-based accelerators has been developed at Lawrence Berkeley National Laboratory. A detailed description of the hardware and the design concept is presented, as well as a performance evaluation of the spectrometer. The spectrometer covered electron beam energies raging from 0.01 to 1.1 GeV in a single shot, and enabled the simultaneous measurement of the laser properties at the exit of the accelerator through the use of a sufficiently large pole gap. Based on measured field maps and 3rd-order transport analysis, a few percent-level resolution and determination of the absolute energy were achieved over the entire energy range. Laser-plasma-based accelerator experiments demonstrated the capability of the spectrometer as a diagnostic and its suitability for such a broadband electron source.

  7. Design of intrinsically single-mode double clad crystalline fiber waveguides for high power lasers

    NASA Astrophysics Data System (ADS)

    Li, Da; Hong, Pengda; Meissner, Stephanie K.; Meissner, Helmuth E.

    2016-03-01

    Recently, double-clad crystalline fiber waveguides (CFWs), consisting of single crystalline or ceramic RE3+:YAG cores of square cross section and inner claddings of either undoped or laser-inactive-ion-doped YAG and outer claddings of sapphire, have been successfully demonstrated. These waveguides, manufactured by an Adhesive-Free Bonding (AFB®) technique, can be precisely engineered and fabricated with predictable beam propagation behavior. In this work, with high power laser designs in mind, minimum thicknesses for inner cladding are derived for different core cross sections and refractive index differences between the core and inner cladding and sapphire as outer cladding material for common laser core dopants such as Nd3+, Yb3+, Er3+, Tm3+ and Ho3+. All designs are intended to use high NA high power laser diode pumping to obtain high power intrinsically single transverse mode laser output. The obtained data are applicable to any crystalline fiber waveguide design, regardless of fabrication technique. As an example, a CFW with 40 μm × 40 μm 4% Tm:YAG core, 5% Yb:YAG inner cladding, and sapphire outer cladding was calculated to be intrinsically single transverse mode, with the minimum inner cladding width of 21.7 μm determined by the effective index technique [1].

  8. Design and fabrication of high power single mode double-trench ridge waveguide laser

    NASA Astrophysics Data System (ADS)

    Tan, Shaoyang; Zhai, Teng; Wang, Wei; Zhang, Ruikang; Lu, Dan; Ji, Chen

    2014-03-01

    A high power single-lateral-mode double-trench ridge waveguide semiconductor laser is reported. The laser has a compressively strained double quantum-well (DQW) and an GaAs/AlGaAs separate confinement structure. The ridge waveguide is defined by two trenches of finite width on either side of the ridge, which will result mode radiation towards outside of the trenches. The relationship between the leakage loss and the waveguide geometry of the each lateral mode is studied with effective index method. The relationship under different bias condition is evaluated. Based on the simulation, lasers with various trench width, trench depth and ridge width are fabricated and tested. With optimized geometry parameters, a laser of 1.5-mm cavity length with a maximum single-lateral-mode operation current of 550 mA is obtained. The threshold current and the slope efficiency of the laser is 30 mA and 0.72 W/A, respectively. The maximum single-lateral-mode power is up to 340 mW.

  9. Wavelength tunable single freqeuncy bistability erbium-doped fiber ring laser

    NASA Astrophysics Data System (ADS)

    Wang, Tianshu; Qian, Sheng; Zhou, Xuefang; Qi, Yongmin; Li, Qiliang

    2008-11-01

    In this paper, a tunable single-frequency fiber laser is designed. For narrow linewidth and single frequency operation, a length of 2.75m unpumped EDF as a saturable absorber is used. The FBG combined with the unpumped EDF provides narrow frequency selection. Counter propagating beams in the unpumped EDF form a standing wave that results in periodic spatial hole burning. This creates a narrower bandwidth absorption grating than the FBG. The output laser wavelength can be changed from 1530nm to 1570nm by the FBG. The 3dB spectrum width of output laser is 0.08nm and the side mode suppression ratio is 55dB. The maximum output power exceeds 12mW, and the stability is less than +/-0.005dB. A nice single-frequency laser is observed. From the relationship of the pump power and output power, it is obvious that the optical bistability switchable phenomena is showed in output characteristics. The bistability switchable phenomena is caused by the saturable absorber in the ring cavity. A 10Gb/s codes rate is used in the fiber laser transmission experiment. The high speed optical signal is transmitted in long distance without regeneration. The eye diagrams of optical transmission are measured, the performance of long haul transmission with high speed modulation is perfect.

  10. 1.5 W green light generation by single-pass second harmonic generation of a single-frequency tapered diode laser.

    PubMed

    Jensen, Ole Bjarlin; Andersen, Peter E; Sumpf, Bernd; Hasler, Karl-Heinz; Erbert, Götz; Petersen, Paul Michael

    2009-04-13

    More than 1.5 W of green light at 531 nm is generated by single-pass second harmonic generation in periodically poled MgO:LiNbO3. The pump laser is a high power tapered laser with a distributed Bragg reflector etched in the ridge section of the laser to provide wavelength selectivity. The output power of the single-frequency tapered laser is 9.3 W in continuous wave operation. A conversion efficiency of 18.5 % was achieved in the experiments. PMID:19365478

  11. A parametric study of single-wall carbon nanotube growth by laser ablation

    NASA Technical Reports Server (NTRS)

    Arepalli, Sivaram; Holmes, William A.; Nikolaev, Pavel; Hadjiev, Victor G.; Scott, Carl D.

    2004-01-01

    Results of a parametric study of carbon nanotube production by the double-pulse laser oven process are presented. The effect of various operating parameters on the production of single-wall carbon nanotubes (SWCNTs) is estimated by characterizing the nanotube material using analytical techniques, including scanning electron microscopy, transmission electron microscopy, thermo gravimetric analysis and Raman spectroscopy. The study included changing the sequence of the laser pulses, laser energy, pulse separation, type of buffer gas used, operating pressure, flow rate, inner tube diameter, as well as its material, and oven temperature. It was found that the material quality and quantity improve with deviation from normal operation parameters such as laser energy density higher than 1.5 J/cm2, pressure lower than 67 kPa, and flow rates higher than 100 sccm. Use of helium produced mainly small diameter tubes and a lower yield. The diameter of SWCNTs decreases with decreasing oven temperature and lower flow rates.

  12. Printed Large-Area Single-Mode Photonic Crystal Bandedge Surface-Emitting Lasers on Silicon.

    PubMed

    Zhao, Deyin; Liu, Shihchia; Yang, Hongjun; Ma, Zhenqiang; Reuterskiöld-Hedlund, Carl; Hammar, Mattias; Zhou, Weidong

    2016-01-01

    We report here an optically pumped hybrid III-V/Si photoic crystal surface emitting laser (PCSEL), consisting of a heterogeneously integrated III-V InGaAsP quantum well heterostructure gain medium, printed on a patterned defect-free Si photonic crystal (PC) bandedge cavity. Single mode lasing was achieved for a large area laser, with a side-mode suppression ratio of 28 dB, for lasing operation temperature ~ 200 K. Two types of lasers were demonstrated operating at different temperatures. Detailed modal analysis reveals the lasing mode matches with the estimated lasing gain threshold conditions. Our demonstration promises a hybrid laser sources on Si towards three-dimensional (3D) integrated Si photonics for on-chip wavelength-division multiplex (3D WDM) systems for a wide range of volume photonic/electronic applications in computing, communication, sensing, imaging, etc. PMID:26727551

  13. Fully referenced single-comb interferometry using optical sampling by laser-cavity tuning.

    PubMed

    Potvin, Simon; Boudreau, Sylvain; Deschênes, Jean-Daniel; Genest, Jérôme

    2013-01-10

    The correction of setup and laser instabilities in a single-comb interferometric measurement using optical sampling by laser-cavity tuning is investigated. A two-reference solution that allows full correction of the interferogram is presented. The technique is compared to a slightly simpler one-reference correction. For the one-reference case, all the subtleties involved in this partial correction and the dependence between the achievable measurement accuracy and the setup parameters are highlighted. The parameters considered are the comb bandwidth, the laser-frequency noise, the required spectral resolution, the cavity scan speed, and the length of the delay line. For both referencing approaches, experimental results using a fiber delay line of 10 km and a 100 MHz mode-locked laser with its repetition rate swept at 500 Hz are shown. PMID:23314642

  14. Printed Large-Area Single-Mode Photonic Crystal Bandedge Surface-Emitting Lasers on Silicon

    PubMed Central

    Zhao, Deyin; Liu, Shihchia; Yang, Hongjun; Ma, Zhenqiang; Reuterskiöld-Hedlund, Carl; Hammar, Mattias; Zhou, Weidong

    2016-01-01

    We report here an optically pumped hybrid III-V/Si photoic crystal surface emitting laser (PCSEL), consisting of a heterogeneously integrated III-V InGaAsP quantum well heterostructure gain medium, printed on a patterned defect-free Si photonic crystal (PC) bandedge cavity. Single mode lasing was achieved for a large area laser, with a side-mode suppression ratio of 28 dB, for lasing operation temperature ~200 K. Two types of lasers were demonstrated operating at different temperatures. Detailed modal analysis reveals the lasing mode matches with the estimated lasing gain threshold conditions. Our demonstration promises a hybrid laser sources on Si towards three-dimensional (3D) integrated Si photonics for on-chip wavelength-division multiplex (3D WDM) systems for a wide range of volume photonic/electronic applications in computing, communication, sensing, imaging, etc. PMID:26727551

  15. High efficiency single frequency 355 nm all-solid-state UV laser

    NASA Astrophysics Data System (ADS)

    Xie, Xiaobing; Wei, Daikang; Ma, Xiuhua; Li, Shiguang; Liu, Jiqiao; Zhu, Xiaolei; Chen, Weibiao

    2016-05-01

    A novel conductively cooled high energy single-frequency 355 nm all-solid-state UV laser is presented based on sum-frequency mixing technique. In this system, a pulsed seeder laser at 1064 nm wavelength, modulated by an AOM, is directly amplified by the cascaded multi-stage hybrid laser amplifiers, and two LBO crystals are used for the SHG and SFG, finally a maximum UV pulse energy of 226 mJ at 355 nm wavelength is achieved with frequency-tripled conversion efficiency as high as 55%, the pulse width is around 12.2 ns at the repetition frequency of 30 Hz. The beam quality factor M 2 of the output UV laser is measured to be 2.54 and 2.98 respectively in two orthogonal directions.

  16. Ultralow threshold graded-index separate-confinement heterostructure single quantum well (Al, Ga) As lasers

    NASA Technical Reports Server (NTRS)

    Derry, P. L.; Chen, H. Z.; Morkoc, H.; Yariv, A.; Lau, K. Y.

    1988-01-01

    Broad area graded-index separate-confinement heterostructure single quantum well lasers grown by molecular-beam epitaxy (MBE) with threshold current density as low as 93 A/sq cm (520 microns long) have been fabricated. Buried lasers formed from similarly structured MBE material with liquid phase epitaxy regrowth had threshold currents at submilliampere levels when high reflectivity coatings were applied to the end facets. A CW threshold current of 0.55 mA was obtained for a laser with facet reflectivities of about 80 percent, a cavity length of 120 micron, and an active region stripe width of 1 micron. These devices driven directly with logic level signals have switch-on delays less than 50 ps without any current prebias. Such lasers permit fully on-off switching while at the same time obviating the need for bias monitoring and feedback control.

  17. Laser interactions with embedded Ca metal nanoparticles in single crystal CaF{sub 2}

    SciTech Connect

    Cramer, L.P.; Schubert, B.E.; Petite, P.S.; Langford, S.C.; Dickinson, J.T.

    2005-04-01

    Single crystal calcium fluoride (CaF{sub 2}) is an important material for vacuum-ultraviolet optics. Nevertheless, prolonged exposure to energetic radiation can color the material by producing calcium metal nanoparticles. We compare the effectiveness of laser conditioning treatments at wavelengths ranging from the near infrared to the deep ultraviolet in removing this coloration. Treatments at 157, 532, and 1064 nm can significantly reduce the visible coloration due to nanoparticles. In contrast, irradiation at 248 nm has little effect at fluences below the damage threshold for the material employed in this work. We present evidence that the effect of laser irradiation on coloration is principally thermal and is largely confined to the first 50 ns after each laser pulse. We attribute the wavelength dependence of the bleaching process to the wavelength dependence associated with Mie absorption by metal nanoparticles. The consequences of these observations with regard to laser conditioning processes in bulk optical materials are discussed.

  18. Printed Large-Area Single-Mode Photonic Crystal Bandedge Surface-Emitting Lasers on Silicon

    NASA Astrophysics Data System (ADS)

    Zhao, Deyin; Liu, Shihchia; Yang, Hongjun; Ma, Zhenqiang; Reuterskiöld-Hedlund, Carl; Hammar, Mattias; Zhou, Weidong

    2016-01-01

    We report here an optically pumped hybrid III-V/Si photoic crystal surface emitting laser (PCSEL), consisting of a heterogeneously integrated III-V InGaAsP quantum well heterostructure gain medium, printed on a patterned defect-free Si photonic crystal (PC) bandedge cavity. Single mode lasing was achieved for a large area laser, with a side-mode suppression ratio of 28 dB, for lasing operation temperature ~200 K. Two types of lasers were demonstrated operating at different temperatures. Detailed modal analysis reveals the lasing mode matches with the estimated lasing gain threshold conditions. Our demonstration promises a hybrid laser sources on Si towards three-dimensional (3D) integrated Si photonics for on-chip wavelength-division multiplex (3D WDM) systems for a wide range of volume photonic/electronic applications in computing, communication, sensing, imaging, etc.

  19. Frequency Noise Suppression of a Single Mode Laser with an Unbalanced Fiber Interferometer for Subnanometer Interferometry

    PubMed Central

    Šmíd, Radek; Čížek, Martin; Mikel, Břetislav; Číp, Ondřej

    2015-01-01

    We present a method of noise suppression of laser diodes by an unbalanced Michelson fiber interferometer. The unstabilized laser source is represented by compact planar waveguide external cavity laser module, ORIONTM (Redfern Integrated Optics, Inc.), working at 1540.57 nm with a 1.5-kHz linewidth. We built up the unbalanced Michelson interferometer with a 2.09 km-long arm based on the standard telecommunication single-mode fiber (SMF-28) spool to suppress the frequency noise by the servo-loop control by 20 dB to 40 dB within the Fourier frequency range, remaining the tuning range of the laser frequency. PMID:25587980

  20. CW single transverse mode all-fiber Tm3+-doped silica fiber laser

    NASA Astrophysics Data System (ADS)

    Song, E. Z.; Li, W. H.; You, L.

    2012-04-01

    The CW 25.6 W output power with a slope efficiency of 30.6% respected to the pump power from a CW single transverse mode all-fiber Tm3+-doped Silica Fiber Laser is reported. The all-fiber laser is made up by progressively splicing the pigtail fiber, matched FBG fiber and Tm fiber. The reflective FBG and Tm3+-doped fiber end Fresnel reflection build up the laser resonance cavity. Due to the multi-mode FBG as the reflective mirror, the output laser spectrum is multi-peaks at high output power, but the spectrum width is less than 2 nm at 1.94 μm. We estimate the beam quality to be M 2 = 2.39, clearly indicating nearly diffraction-limited beam propagation.

  1. Electron acceleration in relativistic plasma waves generated by a single frequency short-pulse laser

    SciTech Connect

    Coverdale, C.A.; Darrow, C.B.; Decker, C.D.; Mori, W.B.; Tzeng, K.C., Clayton, C.E.; Marsh, K.A.; Joshi, C.

    1995-04-27

    Experimental evidence for the acceleration of electrons in a relativistic plasma wave generated by Raman forward scattering (SRS-F) of a single-frequency short pulse laser are presented. A 1.053 {mu}m, 600 fsec, 5 TW laser was focused into a gas jet with a peak intensity of 8{times}10{sup 17} W/cm{sup 2}. At a plasma density of 2{times}10{sup 19} cm{sup {minus}3}, 2 MeV electrons were detected and their appearance was correlated with the anti-Stokes laser sideband generated by SRS-F. The results are in good agreement with 2-D PIC simulations. The use of short pulse lasers for making ultra-high gradient accelerators is explored.

  2. Frequency noise suppression of a single mode laser with an unbalanced fiber interferometer for subnanometer interferometry.

    PubMed

    Šmíd, Radek; Čížek, Martin; Mikel, Břetislav; Číp, Ondřej

    2015-01-01

    We present a method of noise suppression of laser diodes by an unbalanced Michelson fiber interferometer. The unstabilized laser source is represented by compact planar waveguide external cavity laser module, ORIONTM (Redfern Integrated Optics, Inc.), working at 1540.57 nm with a 1.5-kHz linewidth. We built up the unbalanced Michelson interferometer with a 2.09 km-long arm based on the standard telecommunication single-mode fiber (SMF-28) spool to suppress the frequency noise by the servo-loop control by 20 dB to 40 dB within the Fourier frequency range, remaining the tuning range of the laser frequency. PMID:25587980

  3. Second-order interference of two independent and tunable single-mode continuous-wave lasers

    NASA Astrophysics Data System (ADS)

    Jianbin, Liu; Dong, Wei; Hui, Chen; Yu, Zhou; Huaibin, Zheng; Hong, Gao; Fu-Li, Li; Zhuo, Xu

    2016-03-01

    The second-order temporal interference of two independent single-mode continuous-wave lasers is discussed by employing two-photon interference in Feynman’s path integral theory. It is concluded that whether the second-order temporal interference pattern can or cannot be retrieved via two-photon coincidence counting rate is dependent on the resolution time of the detection system and the frequency difference between these two lasers. Two identical and tunable single-mode continuous-wave diode lasers are employed to verify the predictions. These studies are helpful to understand the physics of two-photon interference with photons of different spectra. Project supported by the National Natural Science Foundation of China (Grant No. 11404255) and the Doctor Foundation of Education Ministry of China (Grant No. 20130201120013).

  4. Single-shot ablation threshold of chromium using UV femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Banerjee, S. P.; Fedosejevs, R.

    2014-07-01

    Single-shot ablation threshold for thin chromium film was studied using 266 nm, femtosecond laser pulses. Chromium is a useful material in the nanotechnology industry and information on ablation threshold using UV femtosecond pulses would help in precise micromachining of the material. The ablation threshold was determined by measuring the ablation crater diameters as a function of incident laser pulse energy. Absorption of 266 nm light on the chromium film was also measured under our experimental conditions, and the absorbed energy single-shot ablation threshold fluence was 46 ± 5 mJ/cm2. The experimental ablation threshold fluence value was compared to time-dependent heat flow calculations based on the two temperature model for ultrafast laser pulses. The model predicts a value of 31.6 mJ/cm2 which is qualitatively consistent with the experimentally obtained value, given the simplicity of the model.

  5. Polarized three-photon-pumped laser in a single MOF microcrystal

    PubMed Central

    He, Huajun; Ma, En; Cui, Yuanjing; Yu, Jiancan; Yang, Yu; Song, Tao; Wu, Chuan-De; Chen, Xueyuan; Chen, Banglin; Qian, Guodong

    2016-01-01

    Higher order multiphoton-pumped polarized lasers have fundamental technological importance. Although they can be used to in vivo imaging, their application has yet to be realized. Here we show the first polarized three-photon-pumped (3PP) microcavity laser in a single host–guest composite metal–organic framework (MOF) crystal, via a controllable in situ self-assembly strategy. The highly oriented assembly of dye molecules within the MOF provides an opportunity to achieve 3PP lasing with a low lasing threshold and a very high-quality factor on excitation. Furthermore, the 3PP lasing generated from composite MOF is perfectly polarized. These findings may eventually open up a new route to the exploitation of multiphoton-pumped solid-state laser in single MOF microcrystal (or nanocrystal) for future optoelectronic and biomedical applications. PMID:26983592

  6. 11-GHz waveguide Nd:YAG laser CW mode-locked with single-layer graphene

    PubMed Central

    Okhrimchuk, Andrey G.; Obraztsov, Petr A.

    2015-01-01

    We report stable, passive, continuous-wave (CW) mode-locking of a compact diode-pumped waveguide Nd:YAG laser with a single-layer graphene saturable absorber. The depressed cladding waveguide in the Nd:YAG crystal is fabricated with an ultrafast laser inscription method. The saturable absorber is formed by direct deposition of CVD single-layer graphene on the output coupler. The few millimeter-long cavity provides generation of 16-ps pulses with repetition rates in the GHz range (up to 11.3 GHz) and 12 mW average power. Stable CW mode-locking operation is achieved by controlling the group delay dispersion in the laser cavity with a Gires–Tournois interferometer. PMID:26052678

  7. 11-GHz waveguide Nd:YAG laser CW mode-locked with single-layer graphene.

    PubMed

    Okhrimchuk, Andrey G; Obraztsov, Petr A

    2015-01-01

    We report stable, passive, continuous-wave (CW) mode-locking of a compact diode-pumped waveguide Nd:YAG laser with a single-layer graphene saturable absorber. The depressed cladding waveguide in the Nd:YAG crystal is fabricated with an ultrafast laser inscription method. The saturable absorber is formed by direct deposition of CVD single-layer graphene on the output coupler. The few millimeter-long cavity provides generation of 16-ps pulses with repetition rates in the GHz range (up to 11.3 GHz) and 12 mW average power. Stable CW mode-locking operation is achieved by controlling the group delay dispersion in the laser cavity with a Gires-Tournois interferometer. PMID:26052678

  8. Polarized three-photon-pumped laser in a single MOF microcrystal

    NASA Astrophysics Data System (ADS)

    He, Huajun; Ma, En; Cui, Yuanjing; Yu, Jiancan; Yang, Yu; Song, Tao; Wu, Chuan-De; Chen, Xueyuan; Chen, Banglin; Qian, Guodong

    2016-03-01

    Higher order multiphoton-pumped polarized lasers have fundamental technological importance. Although they can be used to in vivo imaging, their application has yet to be realized. Here we show the first polarized three-photon-pumped (3PP) microcavity laser in a single host-guest composite metal-organic framework (MOF) crystal, via a controllable in situ self-assembly strategy. The highly oriented assembly of dye molecules within the MOF provides an opportunity to achieve 3PP lasing with a low lasing threshold and a very high-quality factor on excitation. Furthermore, the 3PP lasing generated from composite MOF is perfectly polarized. These findings may eventually open up a new route to the exploitation of multiphoton-pumped solid-state laser in single MOF microcrystal (or nanocrystal) for future optoelectronic and biomedical applications.

  9. Ultra-intense single attosecond pulse generated from circularly polarized laser interacting with overdense plasma

    NASA Astrophysics Data System (ADS)

    Ji, Liangliang; Shen, Baifei; Zhang, Xiaomei; Wen, Meng; Xia, Changquan; Wang, Wenpeng; Xu, Jiancai; Yu, Yahong; Yu, Mingyang; Xu, Zhizhan

    2011-08-01

    Few-cycle relativistic circularly polarized (CP) laser pulse reflected from overdense plasma is investigated by analysis and particle-in-cell simulations. It is found that through the laser-induced one-time drastic oscillation of the plasma boundary, an ultra-intense single attosecond light pulse can be generated naturally. An analytical model is proposed to describe the interaction and it agrees well with simulation results. They both indicate that peak intensity of the generated attosecond pulse is higher when the plasma density is closer to the relativistic transparency threshold and/or the pulse duration is closer to plasma oscillating period. Two dimensional simulation shows that a two-cycle 1021 W/cm2 CP laser can generate a single 230 attosecond 2 × 1021 W/cm2 pulse of light at a conversion efficiency greater than 10-2.

  10. Ultra-intense single attosecond pulse generated from circularly polarized laser interacting with overdense plasma

    SciTech Connect

    Ji Liangliang; Shen Baifei; Zhang Xiaomei; Wen Meng; Xia Changquan; Wang Wenpeng; Xu Jiancai; Yu Yahong; Xu Zhizhan; Yu Mingyang

    2011-08-15

    Few-cycle relativistic circularly polarized (CP) laser pulse reflected from overdense plasma is investigated by analysis and particle-in-cell simulations. It is found that through the laser-induced one-time drastic oscillation of the plasma boundary, an ultra-intense single attosecond light pulse can be generated naturally. An analytical model is proposed to describe the interaction and it agrees well with simulation results. They both indicate that peak intensity of the generated attosecond pulse is higher when the plasma density is closer to the relativistic transparency threshold and/or the pulse duration is closer to plasma oscillating period. Two dimensional simulation shows that a two-cycle 10{sup 21} W/cm{sup 2} CP laser can generate a single 230 attosecond 2 x 10{sup 21} W/cm{sup 2} pulse of light at a conversion efficiency greater than 10{sup -2}.

  11. Optical frequency standard based upon single laser-cooled indium ion

    SciTech Connect

    Nagourney, Warren; Torgerson, Justin; Dehmelt, Hans

    1999-01-15

    The current state of our single indium ion work will be presented, with emphasis on the construction of a narrow, solid-state source of tunable UV radiation which will serve as a 'clock' laser for the single-ion standard. Indium is shown to be a favorable candidate for a standard with a long term inaccuracy of less than one part in 10{sup 17}. Its advantages are small systematic errors which are well-understood and relatively straightforward generation of the cooling and 'clock' radiation. The stringent requirements on the long term stability of the 'flywheel' clock laser and the difficulty in coherently relating the optical clock laser frequency to a convenient microwave source are problems which should soon be overcome.

  12. Secondary plasma formation after single pulse laser ablation underwater and its advantages for laser induced breakdown spectroscopy (LIBS).

    PubMed

    Gavrilović, M R; Cvejić, M; Lazic, V; Jovićević, S

    2016-06-01

    In this work we present studies of spatial and temporal plasma evolution after single pulse ablation of an aluminium target in water. The laser ablation was performed using 20 ns long pulses emitted at 1064 nm. The plasma characterization was performed by fast photography, the Schlieren technique, shadowgraphy and optical emission spectroscopy. The experimental results indicate the existence of two distinct plasma stages: the first stage has a duration of approximately 500 ns from the laser pulse, and is followed by a new plasma growth starting from the crater center. The secondary plasma slowly evolves inside the growing vapor bubble, and its optical emission lasts over several tens of microseconds. Later, the hot glowing particles, trapped inside the vapor cavity, were detected during the whole cycle of the bubble, where the first collapse occurs after 475 μs from the laser pulse. Differences in the plasma properties during the two evolution phases are discussed, with an accent on the optical emission since its detection is of primary importance for LIBS. Here we demonstrate that the LIBS signal quality in single pulse excitation underwater can be greatly enhanced by detecting only the secondary plasma emission, and also by applying long acquisition gates (in the order of 10-100 μs). The presented results are of great importance for LIBS measurements inside a liquid environment, since they prove that a good analytical signal can be obtained by using nanosecond pulses from a single commercial laser source and by employing cost effective, not gated detectors. PMID:27180875

  13. Amplification of multiple genomic loci from single cells isolated by laser micro-dissection of tissues

    PubMed Central

    Frumkin, Dan; Wasserstrom, Adam; Itzkovitz, Shalev; Harmelin, Alon; Rechavi, Gideon; Shapiro, Ehud

    2008-01-01

    Background Whole genome amplification (WGA) and laser assisted micro-dissection represent two recently developed technologies that can greatly advance biological and medical research. WGA allows the analysis of multiple genomic loci from a single genome and has been performed on single cells from cell suspensions and from enzymatically-digested tissues. Laser micro-dissection makes it possible to isolate specific single cells from heterogeneous tissues. Results Here we applied for the first time WGA on laser micro-dissected single cells from stained tissue sections, and developed a protocol for sequentially performing the two procedures. The combined procedure allows correlating the cell's genome with its natural morphology and precise anatomical position. From each cell we amplified 122 genomic and mitochondrial loci. In cells obtained from fresh tissue sections, 64.5% of alleles successfully amplified to ~700000 copies each, and mitochondrial DNA was amplified successfully in all cells. Multiplex PCR amplification and analysis of cells from pre-stored sections yielded significantly poorer results. Sequencing and capillary electrophoresis of WGA products allowed detection of slippage mutations in microsatellites (MS), and point mutations in P53. Conclusion Comprehensive genomic analysis of single cells from stained tissue sections opens new research opportunities for cell lineage and depth analyses, genome-wide mutation surveys, and other single cell assays. PMID:18284708

  14. Review of Laser Ablation Process for Single Wall Carbon Nanotube Production

    NASA Technical Reports Server (NTRS)

    Arepalli, Sivaram

    2003-01-01

    Different types of lasers are now routinely used to prepare single wall carbon nanotubes (SWCNTs). The original method developed by researchers at Rice University utilized a "double pulse laser oven" process. A graphite target containing about 1 atomic percent of metal catalysts is ablated inside a 1473K oven using laser pulses (10 ns pulse width) in slow flowing argon. Two YAG lasers with a green pulse (532 nm) followed by an IR pulse (1064 nm) with a 50 ns delay are used for ablation. This set up produced single wall carbon nanotube material with about 70% purity having a diameter distribution peaked around 1.4 nm. The impurities consist of fullerenes, metal catalyst clusters (10 to 100 nm diameter) and amorphous carbon. The rate of production with the initial set up was about 60 mg per hour with 10Hz laser systems. Several researchers have used variations of the lasers to improve the rate, consistency and study effects of different process parameters on the quality and quantity of SWCNTs. These variations include one to three YAG laser systems (Green, Green and IR), different pulse widths (nano to microseconds as well as continuous) and different laser wavelengths (Alexandrite, CO, CO2, free electron lasers in the near to far infrared). It is noted that yield from the single laser (Green or IR) systems is only a fraction of the two laser systems. The yield seemed to scale up with the repetition rate of the laser systems (10 to 60 Hz) and depended on the beam uniformity and quality of the laser pulses. The shift to longer wavelength lasers (free electron, CO and CO2) did not improve the quality, but increased the rate of production because these lasers are either continuous (CW) or high repetition rate pulses (kHz to MHz). The average power and the peak power of the lasers seem to influence the yields. Very high peak powers (MegaWatts per square centimeter) are noted to increase ablation of bigger particles with reduced yields of SWCNTs. Increased average powers

  15. Single mimivirus particles intercepted and imaged with an X-ray laser (CXIDB ID 2)

    DOE Data Explorer

    Seibert, M. Marvin; Ekeberg, Tomas

    2011-02-02

    These are the files used to reconstruct the images in the paper "Single Mimivirus particles intercepted and imaged with an X-ray laser". Besides the diffracted intensities, the Hawk configuration files used for the reconstructions are also provided. The files from CXIDB ID 2 are the pattern and configuration files for the pattern showed in Figure 2b in the paper.

  16. High-power single-mode laser operation using stimulated Rayleigh scattering

    SciTech Connect

    Denariez-Roberge, M.M.; Giuliani, G.

    1981-07-01

    We report single-mode high-power Nd:YAG laser operation by stimulated thermal Rayleigh Q switching. We also analyze the phase-conjugation properties of collinear four-wave mixing that is due to low-frequency excitations in absorbing liquids.

  17. Hybrid single mode lasers fabricated using Si/SiO2/SiON micromachined platforms

    NASA Technical Reports Server (NTRS)

    Ksendzov, A.; Mansour, K.

    2003-01-01

    We have devised a hybridization scheme that, given suitable Fabri-Perot (F-P) ain medium, allows us to fabricate small, mechanically robust single frequency lasers in a wide spectral range, limited only by the transparency of the SiON material.

  18. Prospects for single-molecule detection in liquids by laser-induced fluorescence

    SciTech Connect

    Trkula, M.; Keller, R.A.; Martin, J.C.; Jett, J.H.; Dovichi, N.J.

    1983-01-01

    A laser-induced fluoresence determination of aqueous solutions of rhodamine 6G resulted in a detection limit of 18 attograms, or 22,000 molecules, of rhodamine 6G. These results allow the projection to single-molecule detection with reasonable improvements in the experimental apparatus.

  19. A novel single frequency stabilized Fabry-Perot laser diode at 1590 nm for gas sensing

    NASA Astrophysics Data System (ADS)

    Weldon, Vincent; Boylan, Karl; Corbett, Brian; McDonald, David; O'Gorman, James

    2002-09-01

    A novel single frequency stabilized Fabry-Perot (SFP) laser diode with an emission wavelength of λ=1590 nm for H 2S gas sensing is reported. Sculpting of the multi-mode spectral distribution of a FP laser to achieve single frequency emission is carried out using post growth photolitographic processing of the device. The resulting longitudinal-mode controlled FP laser has a stabilized single frequency emission with a side mode suppression ratio (SMSR) of 40 dB. The application of this device to spectroscopic based H 2S sensing is demonstrated by targeting absorption lines in the wavelength range 1588≤ λ≤1591 nm. Using wavelength modulation spectroscopy (WMS), a low detection limit of 120 ppm.m.Hz -1/2 was estimated while targeting the absorption line at 1590.08 nm. These initial results demonstrate the potential of the stabilized FP laser diode at this wavelength as a tunable, single frequency source for spectroscopic based gas sensing.

  20. Noise amplitude measurements of single-mode CW lasers at radio frequencies

    NASA Technical Reports Server (NTRS)

    Herring, G. C.; Hillard, M. E., Jr.

    1992-01-01

    This letter presents the results of noise measurements for a variety of single-longitudinal-mode CW lasers (Ar/+/, standing-wave-dye, and ring-dye) that are commercially available. A quantitative comparison of the total output power fluctuations detected over the 7-300 MHz region (3 dB points) is presented.

  1. Faint laser pulses versus a single-photon source in free space quantum cryptography

    NASA Astrophysics Data System (ADS)

    Molotkov, S. N.; Potapova, T. A.

    2016-03-01

    In this letter we present estimates for the distance of secret key transmission through free space for three different protocols of quantum key distribution: for BB84 and phase time-coding protocols in the case of a strictly single-photon source, and for the relativistic quantum key distribution protocol in the case of faint laser pulses.

  2. Catastrophic optical mirror damage in diode lasers monitored during single pulse operation

    NASA Astrophysics Data System (ADS)

    Tomm, Jens W.; Ziegler, Mathias; Elsaesser, Thomas; Larsen, Henning E.; Petersen, Paul M.; Andersen, Peter E.; Clausen, Sønnik; Zeimer, Ute; Fendler, David

    2010-02-01

    The catastrophic optical mirror damage (COMD) effect is analyzed for 808 nm emitting diode lasers in single-pulse operation. During each single pulse, both nearfield of the laser emission and thermal image of the laser facet are monitored with cameras being sensitive in the respective spectral regions. A temporal resolution in the μs-range is achieved. The COMD is unambiguously related to the occurrence of a 'thermal flash' detected by thermal imaging. A one-by-one correlation between emission nearfield, 'thermal flash', thermal runaway, and structural damage is observed. As a consequence of the single-pulse-excitation technique, the propagation of 'dark bands' as observed in photo- or cathodoluminescence maps in the plane of the active region from the front facet is halted after the first pulse. Because of the rapidness of the thermal runaway, we propose the single-pulse technique for testing the facet stability and the intentional preparation of early stages of COMD; even for diode lasers that regularly fail by other mechanisms.

  3. Efficient Single-Frequency Thulium Doped Fiber Laser Near 2-micrometers

    NASA Technical Reports Server (NTRS)

    Geng, Jihong; Wu, Jianfeng; Jiang, Shibin; Yu, Jirong

    2007-01-01

    We demonstrate highly efficient diode-pumped single-frequency fiber laser with 35% slope efficiency and 50mW output power operating near 2 micrometers, which generated from a 2-cm long piece of highly Tm(3+)-doped germanate glass fiber pumped at 800nm.

  4. Frontiers in Laser Cooling, Single-Molecule Biophysics, and Enrgy Science: A Talk by Carl Wieman

    ScienceCinema

    Wieman, Carl

    2011-04-13

    Carl Wieman presents a talk at Frontiers in Laser Cooling, Single-Molecule Biophysics and Energy Science, a scientific symposium honoring Steve Chu, director of Lawrence Berkeley National Laboratory and recipient of the 1997 Nobel Prize in Physics. The symposium was held August 30, 2008 in Berkeley.

  5. Single mimivirus particles intercepted and imaged with an X-ray laser (CXIDB ID 1)

    DOE Data Explorer

    Seibert, M. Marvin; Ekeberg, Tomas; Maia, Filipe R.N.C.

    2011-02-02

    These are the files used to reconstruct the images in the paper "Single Mimivirus particles intercepted and imaged with an X-ray laser". Besides the diffracted intensities, the Hawk configuration files used for the reconstructions are also provided. The files from CXIDB ID 1 are the pattern and configuration files for the pattern showed in Figure 2a in the paper.

  6. Single tree biomass modelling using airborne laser scanning

    NASA Astrophysics Data System (ADS)

    Kankare, Ville; Räty, Minna; Yu, Xiaowei; Holopainen, Markus; Vastaranta, Mikko; Kantola, Tuula; Hyyppä, Juha; Hyyppä, Hannu; Alho, Petteri; Viitala, Risto

    2013-11-01

    Accurate forest biomass mapping methods would provide the means for e.g. detecting bioenergy potential, biofuel and forest-bound carbon. The demand for practical biomass mapping methods at all forest levels is growing worldwide, and viable options are being developed. Airborne laser scanning (ALS) is a promising forest biomass mapping technique, due to its capability of measuring the three-dimensional forest vegetation structure. The objective of the study was to develop new methods for tree-level biomass estimation using metrics derived from ALS point clouds and to compare the results with field references collected using destructive sampling and with existing biomass models. The study area was located in Evo, southern Finland. ALS data was collected in 2009 with pulse density equalling approximately 10 pulses/m2. Linear models were developed for the following tree biomass components: total, stem wood, living branch and total canopy biomass. ALS-derived geometric and statistical point metrics were used as explanatory variables when creating the models. The total and stem biomass root mean square error per cents equalled 26.3% and 28.4% for Scots pine (Pinus sylvestris L.), and 36.8% and 27.6% for Norway spruce (Picea abies (L.) H. Karst.), respectively. The results showed that higher estimation accuracy for all biomass components can be achieved with models created in this study compared to existing allometric biomass models when ALS-derived height and diameter were used as input parameters. Best results were achieved when adding field-measured diameter and height as inputs in the existing biomass models. The only exceptions to this were the canopy and living branch biomass estimations for spruce. The achieved results are encouraging for the use of ALS-derived metrics in biomass mapping and for further development of the models.

  7. Single cell transfection by laser-induced breakdown of an optically trapped gold nanoparticle

    NASA Astrophysics Data System (ADS)

    Arita, Yoshihiko; Ploschner, Martin; Antkowiak, Maciej; Gunn-Moore, Frank; Dholakia, Kishan

    2014-03-01

    Cell selective introduction of therapeutic agents remains a challenging problem. Cavitation-based therapies including ultrasound-induced sonoporation and laser-induced optoporation have led the way for novel approaches to provide the potential of sterility and cell selectivity compared with viral or biochemical counterparts. Acoustic streaming, shockwaves and liquid microjets associated with the cavitation dynamics are implicated in gene and drug delivery. These approaches, however, often lead to non-uniform and sporadic molecular uptake that lacks refined spatial control and suffers from a significant loss of cell viability. Here we demonstrate spatially controlled cavitation instigated by laser-induced breakdown of an optically trapped single gold nanoparticle. Our unique approach employs optical tweezers to trap a single nanoparticle, which when irradiated by a nanosecond laser pulse is subject to laser-induced breakdown followed by cavitation. Using this method for laser-induced cavitation, we can gain additional degrees of freedom for the cavitation process - the particle material, its size, and its position relative to cells or tissues. We show the energy breakdown threshold of gold nanoparticles of l00nm with a single nanosecond laser pulse at 532 nm is three orders of magnitude lower than that for water, which leads to gentle nanocavitation enabling single cell transfection. We optimize the shear stress to the cells from the expanding bubble to be in the range of 1-10 kPa for transfection by precisely positioning a trapped gold nanoparticle, and thus nanobubble, relative to a cell of interest. The method shows transfection of plasmid-DNA into individual mammalian cells with an efficiency of 75%.

  8. Broad-area laser diode with stable single-mode output and wavelength stabilization

    NASA Astrophysics Data System (ADS)

    Nappez, Thomas; Ghibaudo, Elise; Rondeau, Philippe; Schlotterbeck, Jean-Pierre; Broquin, Jean-Emmanuel

    2012-01-01

    High power single-mode pump laser diodes operating around 980nm are key components for Erbium-doped devices. Much effort is still currently devoted to improve both their wavelength stability and their achievable output power, while maintaining a stable single-mode operation. Usually, the emission wavelength is stabilized by an external Fiber Bragg Grating (FBG). This configuration requires free-space optics between the laser diode output facet and the fiber or a lensed fiber to ensure an efficient coupling efficiency. This constraint increases fabrication costs, dimensions and mechanical instabilities. Moreover, the maximum achievable output power is limited because a high optical power density can damage the laser facets. To increase the achievable output power, a solution consists in using Broad-Area Laser Diodes (BALD), which are multimode emitters that are composed of large active ribbons with width of some hundreds of micrometers. The objective is then to improve the beam quality by locking the BALD emission on its transverse fundamental mode. We propose in this article to insert an integrated adiabatic transition between the multimode laser and a single-mode FBG. This taper, made by ion-exchange in glass, provides a coupling efficiency of -22.0dB from the multimode laser emission to the single-mode fiber. An optical feedback of -34dB demonstrates the stabilization of the BALD spectrum at the Bragg wavelength. The spectrum of the device is characterized by a maximum side-mode suppression ratio of 35dB, a RMS spectral width of (0.16 +/- 0.04) nm and a frequency shift with current of -12GHz/100mA.

  9. Prototype Test Results for the Single Photon Detection SLR2000 Satellite Laser Ranging System

    NASA Technical Reports Server (NTRS)

    Zagwodzki, Thomas W.; McGarry, Jan F.; Degnan, John J.; Cheek, Jack W.; Dunn, Peter J.; Patterson, Don; Donovan, Howard

    2004-01-01

    NASA's aging Satellite Laser Ranging (SLR) network is scheduled to be replaced over the next few years with a fully automated single photon detection system. A prototype of this new system, called SLR2000, is currently undergoing field trials at the Goddard Space Flight Center in Greenbelt, Maryland to evaluate photon counting techniques and determine system hardware, software, and control algorithm performance levels and limitations. Newly developed diode pumped microchip lasers and quadrant microchannel plate-based photomultiplier tubes have enabled the development of this high repetition rate single photon detection SLR system. The SLR2000 receiver threshold is set at the single photoelectron (pe) level but tracks satellites with an average signal level typically much less than 1 pe. The 2 kHz laser fire rate aids in satellite acquisition and tracking and will enable closed loop tracking by accumulating single photon count statistics in a quadrant detector and using this information to correct for pointing errors. Laser transmitter beamwidths of 10 arcseconds (FWHM) or less are currently being used to maintain an adequate signal level for tracking while the receiver field of view (FOV) has been opened to 40 arcseconds to accommodate point ahead/look behind angular offsets. In the near future, the laser transmitter point ahead will be controlled by a pair of Risley prisms. This will allow the telescope to point behind and enable closure of the receiver FOV to roughly match the transmitter beam divergence. Bandpass filters (BPF) are removed for night tracking operations while 0.2 nm or 1 nm filters are used during daylight operation. Both day and night laser tracking of Low Earth Orbit (LEO) satellites has been achieved with a laser transmitter energy of only 65 microjoules per pulse. Satellite tracking is presently limited to LEO satellites until the brassboard laser transmitter can be upgraded or replaced. Simultaneous tracks have also been observed with NASA s

  10. Comparison between 50 W tapered laser arrays and tapered single emitters

    NASA Astrophysics Data System (ADS)

    Scholz, Christian; Boucke, Konstantin; Poprawe, Reinhart; Keleman, Marc T.; Weber, Jürgen; Mikulla, Michael; Weimann, Günter

    2006-02-01

    During the last few years high power diode laser arrays have become well established for direct material processing due to their high efficiency of more than 50%. But standard broad-area waveguide designs are susceptible to modal instabilities and filamentations resulting in low beam qualities. The beam quality increases by more than a factor of four by using tapered laser arrays, but so far they suffer from lower efficiencies. Therefore tapered lasers are mainly used today as single emitters in external resonator configurations. With increased output power and lifetime, they will be much more attractive for material processing and for pumping of fiber amplifiers. High efficiency tapered mini bars emitting at a wavelength of 980 nm are developed, and in order to qualify the bars, the characteristics of single emitters and mini bars from the same wafer have been compared. The mini bars have a width of 6 mm with 12 emitters. The ridge waveguide tapered lasers consist of a 500 μm long ridge and a 2000 μm long tapered section. The results show very similar behavior of the electro-optical characteristics and the beam quality for single emitters and bars. Due to different junction temperatures, different slope efficiencies were measured: 0.8 W/A for passively cooled mini bars and 1.0 W/A for actively cooled mini-bars and single emitters. The threshold current of 0.7 A per emitter is the same for single emitters and emitter arrays. Output powers of more than 50 W in continuous wave mode for a mini bar with standard packaging demonstrates the increased power of tapered laser bars.

  11. Stable CW Single-Frequency Operation of Fabry-Perot Laser Diodes by Self-Injection Phase Locking

    NASA Technical Reports Server (NTRS)

    Duerksen, Gary L.; Krainak, Michael A.

    1998-01-01

    Previously, single-frequency semiconductor laser operation using fiber Bragg gratings (FBG) has been achieved by two methods: (1) use of the FBG as the output coupler for an anti-reflection-coated semiconductor gain element; (2) pulsed operation of a gain-switched Fabry-Perot laser diode with FBG-optical and RF-electrical feedback. Here, we demonstrate CW single frequency operation from a non-AR coated Fabry-Perot laser diode using only FBG optical feedback.

  12. Stable CW Single Frequency Operation of Fabry-Perot Laser Diodes by Self-Injection Phase Locking

    NASA Technical Reports Server (NTRS)

    Duerksen, Gary L.; Krainak, Michael A.

    1999-01-01

    Previously, single-frequency semiconductor laser operation using fiber Bragg gratings has been achieved by tWo methods: 1) use of the FBG as the output coupler for an anti-reflection-coated semiconductor gain element'; 2) pulsed operation of a gain-switched Fabry-Perot laser diode with FBG-optical and RF-electrical feedback'. Here, we demonstrate CW single frequency operation from a non-AR coated Fabry-Perot laser diode using only FBG optical feedback.

  13. A single amino acid substitution modulates low-pH-triggered membrane fusion of GP64 protein in Autographa californica and Bombyx mori nucleopolyhedroviruses

    SciTech Connect

    Katou, Yasuhiro; Yamada, Hayato; Ikeda, Motoko; Kobayashi, Michihiro

    2010-09-01

    We have previously shown that budded viruses of Bombyx mori nucleopolyhedrovirus (BmNPV) enter the cell cytoplasm but do not migrate into the nuclei of non-permissive Sf9 cells that support a high titer of Autographa californica multicapsid nucleopolyhedrovirus (AcMNPV) multiplication. Here we show, using the syncytium formation assay, that low-pH-triggered membrane fusion of BmNPV GP64 protein (Bm-GP64) is significantly lower than that of AcMNPV GP64 protein (Ac-GP64). Mutational analyses of GP64 proteins revealed that a single amino acid substitution between Ac-GP64 H155 and Bm-GP64 Y153 can have significant positive or negative effects on membrane fusion activity. Studies using bacmid-based GP64 recombinant AcMNPV harboring point-mutated ac-gp64 and bm-gp64 genes showed that Ac-GP64 H155Y and Bm-GP64 Y153H substitutions decreased and increased, respectively, the multiplication and cell-to-cell spread of progeny viruses. These results indicate that Ac-GP64 H155 facilitates the low-pH-triggered membrane fusion reaction between virus envelopes and endosomal membranes.

  14. An Efficient Single Frequency Ho:YLF Laser for IPDA Lidar Applications

    NASA Technical Reports Server (NTRS)

    Yu, J.; Bai, Y.; Wong, T.; Reithmeier, K.; Petros, M.

    2016-01-01

    A highly efficient, versatile, single frequency 2-micron pulsed laser can be used in a pulsed Differential Absorption Lidar (DIAL) / Integrated Path Differential Absorption (IPDA) instrument to make precise, high-resolution measurements to investigate sources and sinks of CO2. For a direct detection IPDA lidar, the desired 2 ?m Ho:YLF laser should generate 30-40 mJ pulses at the repetition rate of 100 to 200 Hz, with short pulse length (<100 ns) and better than 2% wall plug efficiency. A Tm fiber laser in-band pumped Ho:YLF laser has been developed to meet this technical challenge. This Ho:YLF laser is designed in a four mirror ring resonator with bow tie configuration, which helps to obtain high beam quality. It is end-pumped by a 40 W linearly polarized Tm fiber laser at 1.94µm. The resonator length is 1.10 meters with output coupler reflectivity at 45%. The laser crystal size is 3 x 3 x 60 mm (w, h, l) with a doping concentration of 0.5% Holmium. The laser beam and pump beam are mode-matched in the active medium. Thus, the pump and laser beams have the same confocal parameters. Mode-matching is also helpful for operating the laser in a single transverse mode. The laser beam waist is slightly less than 0.5 mm at the center of the laser crystal. Based on quasi-four level modeling, pump absorption and saturation depend on laser intensity. Laser amplification and saturation also depend on the pump intensity in the crystal. The laser is injection seeded to obtain the single frequency required by an IPDA lidar measurement. The seed beam is entered into the resonator through an output coupler. The laser is mounted on a water cooled optical bench for stable and reliable operation. The size of the optical bench is 22.16 x 9.20 x 1.25 inches. It is stiffened so that the laser can be operated in any orientation of the optical bench. This packaged Ho:YLF laser is designed for either mobile trailer or airborne platform operation. The engineering prototype Ho:YLF laser has

  15. Characterization of plasma and laser conditions for single hot spot interaction experiments

    SciTech Connect

    Montgomery, D.S.; Johnson, R.P.; Cobble, J.A.; Fernandez, J.C.; Lindman, E.L.; Rose, H.A.; Estabrook, K.G.

    1998-11-01

    The LANL TRIDENT laser system is being used for fundamental experiments which study the interaction of self-focusing, stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS) in a single (diffraction limited) laser hot spot in order to better understand the coupling between these plasma instabilities. The diffraction limited beam mimics a single hot spot found in speckle distributions that are typical of random or kinoform phase plate (RPP or KPP) smoothing. A long scale length, hot plasma ({approximately} 1 mm, {approximately} 0.5 keV) is created by a separate heater beam, and the single hot spot beam is used to drive parametric instabilities. The focal plane distribution and wavefront of the single hot spot beam are characterized, and the intensity of the single hot spot can be varied between 10{sup 14}--10{sup 16} W/cm{sup 2}. The plasma density, temperature, and flow profiles are measured using gated imaging spectroscopy of collective Thomson scattering. Results of the laser and plasma characterization, and initial results of backscattered SRS, SBS, and beam steering in a flowing plasma are presented.

  16. A yolk-like multifunctional platform for multimodal imaging and synergistic therapy triggered by a single near-infrared light.

    PubMed

    Lv, Ruichan; Yang, Piaoping; He, Fei; Gai, Shili; Li, Chunxia; Dai, Yunlu; Yang, Guixin; Lin, Jun

    2015-02-24

    To integrate photodynamic therapy (PDT) with photothermal therapy (PTT) and chemotherapy for enhanced antitumor efficiency, we developed a mild and rational route to synthesize novel multifunctional GdOF:Ln@SiO2 (Ln = 10%Yb/1%Er/4%Mn) mesoporous capsules using strong up-conversion luminescent (UCL) GdOF:Ln as cores and mesoporous silica layer as shells, followed by modification with varied functional groups onto the framework. It was found that due to the codoped Yb/Er/Mn in GdOF, the markedly enhanced red emission can efficiently transfer energy to the conjugated PDT agent (ZnPc) which produces high singlet oxygen, and the incorporated carbon dots outside the shell can generate obvious thermal effect under 980 nm laser irradiation and also prevent the premature leaking of ZnPc. Simultaneously, the as-produced thermal effect can obviously enhance the doxorubicin (DOX) release, which greatly improves the chemotherapy, resulting in a synergistic therapeutic effect. The system exhibits drastically enhanced therapeutic efficiency against tumor growth, as demonstrated both in vitro and in vivo. Especially, the doped rare earth ions in the host endow the material with excellent UCL imaging, magnetic resonance imaging (MRI), and computed tomography (CT) imaging properties, thus realizing the target of multimodal imaging guided multiple therapies. PMID:25581331

  17. Continuous wave Cs diode pumped alkali laser pumped by single emitter narrowband laser diode.

    PubMed

    Zhdanov, B V; Venus, G; Smirnov, V; Glebov, L; Knize, R J

    2015-08-01

    This paper presents results of cooperative efforts on development of a continuous wave Cs diode pumped alkali laser with moderate output power, which can be considered as a prototype of the commercial device. The developed system operates at 895 nm with output power about 4 W and slope efficiency 28%. Measured turn on time of this system from the standby mode is about a minute. PMID:26329171

  18. Noninvasive Laser Probing of Ultrashort Single Electron Bunches for Accelerator And Light Source Development

    SciTech Connect

    Bolton, P.R.; /SLAC

    2007-06-11

    Companion development of ultrafast electron beam diagnostics capable of noninvasively resolving single bunch detail is essential for the development of high energy, high brightness accelerator facilities and associated beam-based light source applications. Existing conventional accelerators can exhibit timing-jitter down to the 100 femtosecond level which exceeds their single bunch duration capability. At the other extreme, in relatively jitterless environments, laser-plasma wakefield accelerators (LWFA) can generate single electron bunches of duration estimated to be of order 10 femtoseconds making this setting a valuable testbed for development of broadband electron bunch diagnostics. Characteristics of electro-optic schemes and laser-induced reflectance are discussed with emphasis on temporal resolution.

  19. Continuous-wave, single-frequency 229  nm laser source for laser cooling of cadmium atoms.

    PubMed

    Kaneda, Yushi; Yarborough, J M; Merzlyak, Yevgeny; Yamaguchi, Atsushi; Hayashida, Keitaro; Ohmae, Noriaki; Katori, Hidetoshi

    2016-02-15

    Continuous-wave output at 229 nm for the application of laser cooling of Cd atoms was generated by the fourth harmonic using two successive second-harmonic generation stages. Employing a single-frequency optically pumped semiconductor laser as a fundamental source, 0.56 W of output at 229 nm was observed with a 10-mm long, Brewster-cut BBO crystal in an external cavity with 1.62 W of 458 nm input. Conversion efficiency from 458 nm to 229 nm was more than 34%. By applying a tapered amplifier (TA) as a fundamental source, we demonstrated magneto-optical trapping of all stable Cd isotopes including isotopes Cd111 and Cd113, which are applicable to optical lattice clocks. PMID:26872168

  20. Single-cell optoporation and transfection using femtosecond laser and optical tweezers.

    PubMed

    Waleed, Muhammad; Hwang, Sun-Uk; Kim, Jung-Dae; Shabbir, Irfan; Shin, Sang-Mo; Lee, Yong-Gu

    2013-01-01

    In this paper, we demonstrate a new single-cell optoporation and transfection technique using a femtosecond Gaussian laser beam and optical tweezers. Tightly focused near-infrared (NIR) femtosecond laser pulse was employed to transiently perforate the cellular membrane at a single point in MCF-7 cancer cells. A distinct technique was developed by trapping the microparticle using optical tweezers to focus the femtosecond laser precisely on the cell membrane to puncture it. Subsequently, an external gene was introduced in the cell by trapping and inserting the same plasmid-coated microparticle into the optoporated cell using optical tweezers. Various experimental parameters such as femtosecond laser exposure power, exposure time, puncture hole size, exact focusing of the femtosecond laser on the cell membrane, and cell healing time were closely analyzed to create the optimal conditions for cell viability. Following the insertion of plasmid-coated microparticles in the cell, the targeted cells exhibited green fluorescent protein (GFP) under the fluorescent microscope, hence confirming successful transfection into the cell. This new optoporation and transfection technique maximizes the level of selectivity and control over the targeted cell, and this may be a breakthrough method through which to induce controllable genetic changes in the cell. PMID:24049675

  1. Single-beam optical biosensing based on enzyme-linked laser nanopolymerization of o-phenylenediamine.

    PubMed

    Yoshikawa, Hiroyuki; Imura, Shuhei; Tamiya, Eiichi

    2012-11-20

    We report an innovative biosensing technique using a focused laser beam for the fabrication of a polymer nanostructure and the detection of its nanoscale growth. A nanoaggregate structure is formed by focusing a single beam of a continuous-wave (cw) green laser beam on an o-phenylenediamine (o-pD) solution dropped on a glass substrate. The backreflection intensity of the focused laser beam shows a temporal oscillation, whereas the size of the aggregate monotonously increases. Simple calculations based on the Fresnel equation qualitatively reproduce the experimental results, indicating that the backreflected laser oscillation occurs because of the interference between two beams reflected at the front and the back surfaces of the aggregate. Because the growth speed of the aggregate depends on light absorption by the oxidized o-PD, the backreflection oscillation curve can be used to monitor the oxidative reaction in the solution. We apply this phenomena to optical biosensing based on the oxidation of o-PD by the peroxidase enzyme reaction. A reliable quantification of glucose can be achieved by simply focusing a single laser beam and detecting its reflection intensity in a manner similar to the optical pickup unit of optical storage drives. PMID:23088661

  2. Fractional Carbon Dioxide Laser for Keratosis Pilaris: A Single-Blind, Randomized, Comparative Study

    PubMed Central

    Vachiramon, Vasanop; Anusaksathien, Pattarin; Kanokrungsee, Silada; Chanprapaph, Kumutnart

    2016-01-01

    Objective. Keratosis pilaris (KP) is a common condition which can frequently be cosmetically disturbing. Topical treatments can be used with limited efficacy. The objective of this study is to evaluate the effectiveness and safety of fractional carbon dioxide (CO2) laser for the treatment of KP. Patients and Methods. A prospective, randomized, single-blinded, intraindividual comparative study was conducted on adult patients with KP. A single session of fractional CO2 laser was performed to one side of arm whereas the contralateral side served as control. Patients were scheduled for follow-up at 4 and 12 weeks after treatment. Clinical improvement was graded subjectively by blinded dermatologists. Patients rated treatment satisfaction at the end of the study. Results. Twenty patients completed the study. All patients stated that the laser treatment improved KP lesions. At 12-week follow-up, 30% of lesions on the laser-treated side had moderate to good improvement according to physicians' global assessment (p = 0.02). Keratotic papules and hyperpigmentation appeared to respond better than the erythematous component. Four patients with Fitzpatrick skin type V developed transient pigmentary alteration. Conclusions. Fractional CO2 laser treatment may be offered to patients with KP. Dark-skinned patients should be treated with special caution. PMID:27247936

  3. Power Scaling of Single-Frequency Hybrid Brillouin/Ytterbium Fiber Lasers

    SciTech Connect

    Guan, W.; Marciante, J.R.

    2010-06-22

    A coupled-wave rate-equation model, including multiple-order stimulated Brillouin scattering (SBS), is used to study power scaling of hybrid Brillouin/ytterbium fiber lasers. To validate the model, a single-frequency, Brillouin/ytterbium fiber laser was built with a laser output of 40 mW and an optical signal-to-noise ratio greater than 50 dB. The numerical model simulation agrees with the measurements in both fully and partially injection locked regimes. To scale up the laser’s output power, a dual-clad architecture is proposed. In this new configuration, the active Yb-doped fiber provides the nonlinear SBS gain as well as the gain resulting from the excited Yb ions. Numerical modeling including three Stokes orders shows that over 5 W of single-frequency laser output can be achieved with a side-mode suppression ratio (SMSR) of greater than 80 dB. Beyond this power, multi-order SBS affects the laser efficiency and SMSR.

  4. Single-walled carbon nanotube passively mode-locked O-band Raman fiber laser

    NASA Astrophysics Data System (ADS)

    Steinberg, D.; Saito, L. A. M.; Rosa, H. G.; Thoroh de Souza, E. A.

    2016-05-01

    We present a detailed analysis of a nanosecond-pulse single-walled carbon nanotube (SWCNT) passively mode-locked O-band Raman fiber lasers. As gain medium, single mode fiber (SMF) and highly nonlinear Raman gain were used at three different experimental setups. By incorporating 1.0 nm mean diameter SWCNT as saturable absorbers (SA) at 2.3 km SMF long-length gain medium setup, soliton-like spectrum followed by nanosecond high chirped pulse was observed at cavity fundamental repetition rate. In order to shorter the chirped pulse, intracavity anomalous dispersion was introduced with normal dispersion shift fiber (DSF) lengths and pulse duration decreased from 4.20 to 2.30 ns. By using highly nonlinear Raman gain medium in the O-band Raman laser configuration, the laser generated clean and well-defined nanosecond high chirped pulses, achieving pulse duration as short as 2.30 ns with 230 m gain medium length. Also, we could estimate the picosecond pulse duration region as a function of gain medium length of this laser and compared with SMF pulse shortening curve. As results, the lasers presented similar tendencies, indicating a strong influence of nonlinearities and dispersion in the pulse duration shortening.

  5. Single-mode, All-Solid-State Nd:YAG Laser Pumped UV Converter

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.; Armstrong, Darrell, J.; Edwards, William C.; Singh, Upendra N.

    2008-01-01

    In this paper, the status of a high-energy, all solid-state Nd:YAG laser pumped nonlinear optics based UV converter development is discussed. The high-energy UV transmitter technology is being developed for ozone sensing applications from space based platforms using differential lidar technique. The goal is to generate greater than 200 mJ/pulse with 10-50 Hz PRF at wavelengths of 308 nm and 320 nm. A diode-pumped, all-solid-state and single longitudinal mode Nd:YAG laser designed to provide conductively cooled operation at 1064 nm has been built and tested. Currently, this pump laser provides an output pulse energy of >1 J/pulse at 50 Hz PRF and a pulsewidth of 22 ns with an electrical-to-optical system efficiency of greater than 7% and a M(sup 2) value of <2. The single frequency UV converter arrangement basically consists of an IR Optical Parametric Oscillator (OPO) and a Sum Frequency Generator (SFG) setups that are pumped by 532 nm wavelength obtained via Second Harmonic Generation (SHG). In this paper, the operation of an inter cavity SFG with CW laser seeding scheme generating 320 nm wavelength is presented. Efforts are underway to improve conversion efficiency of this mJ class UV converter by modifying the spatial beam profile of the pump laser.

  6. Single shot laser flash photolysis with a fibre-coupled reference beam monitor.

    PubMed

    Li, Heng; van 't Hag, Leonie; Yousef, Yaser A; Melø, T B; Razi Naqvi, K

    2013-02-01

    In the standard nanosecond laser photolysis method for kinetic studies, a Q-switched laser generates transient species, and absorption spectrophotometry provides a measure of their concentrations. The sample is placed between the monitoring source (a pulsed xenon arc or a flash lamp) and a monochromator, and a photomultiplier tube (PMT) is used for measuring the intensity of the light leaving the exit slit of the monochromator. With this (single-beam) arrangement, the laser-induced change in the absorbance of the sample, ΔA, can be calculated only if the intensity of the monitoring beam remains constant during the time interval of interest. When this condition is not fulfilled, a second measurement of the PMT output is made after blocking the path of the laser beam, but shot-to-shot variations in the output of the monitoring source vitiate the analysis when ΔA is small. To overcome this problem, double-beam versions were developed in the last century, but the single-beam version still enjoys greater popularity. With a view to making the double-beam method easily implementable, some simple modifications are introduced, which permit the conversion of an existing laser kinetic spectrometer into a double-beam variant (with one or two monochromators). PMID:22990442

  7. Direct-writing lithography using laser diode beam focused with single elliptical microlens

    NASA Astrophysics Data System (ADS)

    Hasan, Md. Nazmul; Haque, Muttahid-Ull; Trisno, Jonathan; Lee, Yung-Chun

    2015-10-01

    A lithography method is proposed for arbitrary patterning using an elliptically diverging laser diode beam focused with a single planoconvex elliptical microlens. Simulations are performed to model the propagation properties of the laser beam and to design the elliptical microlens, which has two different profiles in the x- and y-axis directions. The microlens is fabricated using an excimer laser dragging method and is then attached to the laser diode using double-sided optically cleared adhesive (OCA) tape. Notably, the use of OCA tape removes the need for a complicated alignment procedure and thus significantly reduces the assembly cost. The minimum focused spot of the laser diode beam is investigated by performing single-shot exposure tests on a photoresist (PR) layer. Finally, the practical feasibility of this lithography technique to generate an arbitrary pattern is demonstrated by dotted and continuous features through thin chromium layer deposition on PR and a metal lift-off process. The results show that the minimum feature size for the dotted patterns is around 6.23 μm, while the minimum linewidths for continuous patterns is 6.44 μm. In other words, the proposed focusing technique has significant potential for writing any arbitrary high-resolution pattern for applications like printed circuit board fabrication.

  8. Pulsed Laser CVD Investigations of Single-Wall Carbon Nanotube Growth Dynamics

    SciTech Connect

    Geohegan, David B; Liu, Zuqin; Styers-Barnett, David J; Puretzky, Alexander A; Rouleau, Christopher M; Yuan, Dongning; Ivanov, Ilia N; Xiao, Kai; Liu, Jie

    2008-01-01

    The nucleation and rapid growth of single-wall carbon nanotubes (SWNTs) were explored by pulsed-laser assisted chemical vapor deposition (PLA-CVD). A special high-power, Nd:YAG laser system with tunable pulse width (> 0.5 ms) was implemented to rapidly heat (>30,000 C/s) metal catalyst-covered substrates to different growth temperatures for very brief (sub-second) and controlled time periods as measured by in situ optical pyrometry. Utilizing growth directly on transmission electron microscopy grids, exclusively SWNTs were found to grow under rapid heating conditions, with a minimum nucleation time of >0.10 s. By measuring the length of nanotubes grown by single laser pulses, extremely fast growth rates (up to 100 microns/s) were found to result from the rapid heating and cooling induced by the laser treatment. Subsequent laser pulses were found not to incrementally continue the growth of these nanotubes, but instead activate previously inactive catalyst nanoparticles to grow new nanotubes. Localized growth of nanotubes with variable density was demonstrated through this process, and was applied for the reliable direct-write synthesis of SWNTs onto pre-patterned, catalyst-covered metal electrodes for the synthesis of SWNT field-effect transistors.

  9. Single-frequency Q-switched erbium-doped fiber ring laser by combination of a distributed Bragg reflector laser and a Mach-Zender interferometer.

    PubMed

    Wang, Anting; Ming, Hai; Xie, Jianping; Chen, Xiyao; Lv, Liang; Huang, Wencai; Xu, Lixin

    2003-06-20

    A single-frequency Q-switched erbium-doped fiber ring laser is implemented for producing a single frequency with 25-Mhz laser linewidth, Q-switched pulses with a high peak power at 1557.5 mm. The single longitudinal mode is selected by a distributed Bragg reflector fiber laser, and a fiberoptic Mach-Zehnder interferometer acts as a Q-switch. The peak power and the average power of the Q-switched pulses vary with the repetition rate. PMID:12833955

  10. A low jitter single frequency Q-switched laser from solid state to optical fiber configuration

    NASA Astrophysics Data System (ADS)

    Wu, Frank F.

    2013-03-01

    This paper will get to the bottom of the mechanism of a superior inject seeding technology, and take it even further, from the solid state laser into the fiber laser configuration. This low jitter, single frequency Q-switched solid state laser with precisely controllable firing time was realized, developed and reported previously, in which the oscillator can output energy of near 100 mJ and the master oscillator power amplifier (MOPA) reaches the output energy of 300 mJ, operating at a wavelength of 1064 nm, with a pulse width of 10 ns and in near single transversal mode. Comparing two existing commercial techniques, ramp-and-fire and pulse-to-pulse buildup time reduction, this report presents a full understanding of using a CW transformed injection seeding method in which this technique is immune to mechanical vibration or thermal expansion, and it is able to precisely control the high peak energy launching time within a nanosecond jitter and achieve single frequency operation at the same time. It is carefully observed that the CW seeding mechanism is similar but not equivalent to a pulsed seeding with pulse width shorter or equal to the ring cavity length. The advantage of the realized regime is that in stable laser operation there is no need to adjust the slave cavity length to match the seeded light longitudinal mode. Therefore, the extremely strict mechanical requirement can be relaxed. It is found that the slave laser frequency follows exactly to the injected seeded laser's frequency which can also provide frequency tuning, control and locking.

  11. Compact deep UV laser system at 222.5 nm by single-pass frequency doubling of high-power GaN diode laser emission

    NASA Astrophysics Data System (ADS)

    Ruhnke, Norman; Müller, André; Eppich, Bernd; Güther, Reiner; Maiwald, Martin; Sumpf, Bernd; Erbert, Götz; Tränkle, Günther

    2016-03-01

    Deep ultraviolet (DUV) lasers emitting below 300 nm are of great interest for many applications, for instance in medical diagnostics or for detecting biological agents. Established DUV lasers, e.g. gas lasers or frequency quadrupled solid-state lasers, are relatively bulky and have high power consumptions. A compact and reliable laser diode based system emitting in the DUV could help to address applications in environments where a portable and robust light source with low power consumption is needed. In this work, a compact DUV laser system based on single-pass frequency doubling of highpower GaN diode laser emission is presented. A commercially available high-power GaN laser diode from OSRAM Opto Semiconductors serves as a pump source. The laser diode is spectrally stabilized in an external cavity diode laser (ECDL) setup in Littrow configuration. The ECDL system reaches a maximum optical output power of 700 mW, maintaining narrowband emission below 60 pm (FWHM) at 445 nm over the entire operating range. By direct single pass frequency doubling in a BBO crystal with a length of 7.5 mm a maximum DUV output power of 16 μW at a wavelength of 222.5 nm is generated. The presented concept enables compact and efficient diode laser based light sources emitting in the DUV spectral range that are potentially suitable for in situ applications where a small footprint and low power consumption is essential.

  12. Measurement of UV absorption of single living cell for cell manipulation using NIR femtosecond laser

    NASA Astrophysics Data System (ADS)

    Cho, Sung-Hak; Chang, Won-Seok; Kim, Kwang-Ryul; Hong, Jong Wook

    2009-02-01

    Optical UV absorption of single human living cells ranging from 200 nm to 360 nm was measured in situ for the study of cell manipulation using the near-infrared (NIR) femtosecond laser . Human breast living cells of MCF-10A, MCF-7, and MDA-MB-231 were used in this experiment. The selective photo-disruptions of single living cell and its sub-organelle (nucleus) were also demonstrated using the tightly focused 790 nm wavelength femtosecond laser with pulse duration of 110 fs. It was found that each living cell has its own absorption spectrum in UV wavelength ranges. It was also inferred that intrinsic absorption spectrum is attributed to the amount of DNA and protein of living cell. For the study of photo-disruption of single cell using the multi-photon absorption excited by the NIR femtosecond laser pulse, the origin UV absorption spectrum of targeted living cell is important and fundamental information to understand nonlinear interaction between NIR ultrashort, high-intensity laser light and transparent living cell.

  13. Laser annealing induced ferromagnetism in SrTiO{sub 3} single crystal

    SciTech Connect

    Rao, S. S. Prater, J. T.; Lee, Y. F.; Narayan, J.; Smirnov, A. I.

    2014-07-28

    The appearance of ferromagnetic order up to 400 K upon KrF (248 nm) laser irradiation is reported in un-doped SrTiO{sub 3} (STO) single crystal. The high resolution x-ray photo emission spectroscopy (XPS) measurements reveal a strong shift of Sr-, Ti-, and O-related peaks. X-ray diffraction of laser annealed STO does not reveal a signature of either secondary magnetic or amorphous phases. 300 K X-band (∼9.543 GHz) angle-dependent electron paramagnetic resonance (EPR) measurements showed no evidence of additional magnetic peaks upon laser irradiation. XPS and EPR data did not provide a strong evidence of Ti{sup 3+} formation upon laser annealing. No differences in the visible 300 K Raman spectra of pristine and laser annealed STO are noticed. Interestingly, the magnetic moment is decreased by almost 10-fold upon oxygen annealing of laser annealed STO, inferring that oxygen vacancies play an important role in establishing the observed ferromagnetism.

  14. Numerical optimization approaches of single-pulse conduction laser welding by beam shape tailoring

    NASA Astrophysics Data System (ADS)

    Sundqvist, J.; Kaplan, A. F. H.; Shachaf, L.; Brodsky, A.; Kong, C.; Blackburn, J.; Assuncao, E.; Quintino, L.

    2016-04-01

    While circular laser beams are usually applied in laser welding, for certain applications tailoring of the laser beam shape, e.g. by diffractive optical elements, can optimize the process. A case where overlap conduction mode welding should be used to produce a C-shaped joint was studied. For the dimensions studied in this paper, the weld joint deviated significantly from the C-shape of the single-pulse laser beam. Because of the complex heat flow interactions, the process requires optimization. Three approaches for extracting quantitative indicators for understanding the essential heat flow contributions process and for optimizing the C-shape of the weld and of the laser beam were studied and compared. While integral energy properties through a control volume and temperature gradients at key locations only partially describe the heat flow behaviour, the geometrical properties of the melt pool isotherm proved to be the most reliable method for optimization. While pronouncing the C-ends was not sufficient, an additional enlargement of the laser beam produced the desired C-shaped weld joint. The approach is analysed and the potential for generalization is discussed.

  15. Oxidative Stress and Plasma Membrane Repair in Single Myoblasts After Femtosecond Laser Photoporation.

    PubMed

    Duan, Xinxing; Chan, Kam Tai; Lee, Kenneth K H; Mak, Arthur F T

    2015-11-01

    Cell membranes are susceptible to biophysical damages. These biophysical damages often present themselves in challenging oxidative environments, such as in chronic inflammation. Here we report the damage evolution after single myoblasts were individually subjected to femtosecond (fs) laser photoporation on their plasma membranes under normal and oxidative conditions. A well-characterized tunable fs laser was coupled with a laser scanning confocal microscope. The post-damage wound evolution was documented by real-time imaging. The fs laser could generate a highly focused hole at a targeted site of the myoblast plasma membrane. The initial hole size depended on the laser dosage in terms of power and exposure duration. With the same laser power and irradiation duration, photoporation invoked bigger holes in the oxidative groups than in the control. Myoblasts showed difficulty in repairing holes with initial size beyond certain threshold. Within the threshold, holes could apparently be resealed within 100 s under the normal condition; while in oxidative condition, the resealing process could take 100-300 s. The hole-resealing capacity of myoblasts was compromised under oxidative stress particularly when the oxidative exposure was chronic. It is interesting to note that brief exposure to oxidative stress apparently could promote resealing in myoblasts after photoporation. PMID:26014361

  16. Numerical analysis of the feedback regimes for a single-mode semiconductor laser with external feedback

    SciTech Connect

    Schunk, N.; Petermann, K.

    1988-07-01

    The effect of external feedback on a single-mode semiconductor laser is estimated by a numerical solution of the nonlinear rate equations, yielding an excellent description experimental results. It is found that the lasing mode with the minimum linewidth is most stable rather than the mode with minimum threshold gain. The transition to the coherence-collapse regime is of particular interest. It usually occurs for feedback fractions approx. = 10/sup -4/, but it may shifted to considerably larger feedback levels by either increasing the emitted optical power, the laser length, or by decreasing the linewidth enhancement factor ..cap alpha...

  17. Spatial resolved temperature measurement based on absorption spectroscopy using a single tunable diode laser

    NASA Astrophysics Data System (ADS)

    Yu, Xilong; Li, Fei; Chen, Lihong; Zhang, Xinyu

    2010-03-01

    A novel method based on wavelength-multiplexed line-of-sight absorption and profile fitting for non-uniform flow field measurement is reported. A wavelength scanning combing laser temperature and current modulation WMS scheme is used to implement the wavelength-multiplexed-profile fitting method. Second harmonic (2f) signal of eight H2O transitions features near 7,170 cm-1 are measured in one period using a single tunable diode laser. Spatial resolved temperature distribution upon a CH4/air premixed flat flame burner is obtained. The result validates the feasibility of strategy for non-uniform flow field diagnostics by means of WMS-2f TDLAS.

  18. Stable multi-wavelength fiber laser with single-mode fiber in a Sagnac loop.

    PubMed

    Wang, Pinghe; Wang, Lei; Shi, Guohua; He, Tiejun; Li, Heping; Liu, Yong

    2016-04-20

    In this paper, we propose and experimentally demonstrate a stable multi-wavelength fiber laser at 1.5 μm with single-mode fiber (SMF). The Sagnac loop structure with a 48.6:51.4 coupler and 2 km SMF has an intensity-dependent loss, which contributes to suppress the mode competition in the cavity and leads to a steady multi-wavelength output. In the experiment, five stable lasing wavelengths are obtained with a pump power of 300 mW at 980 nm. The demonstrated multi-wavelength fiber laser has great potential for applications in optical communications and optical sensing systems. PMID:27140108

  19. Linearly frequency-modulated pulsed single-frequency fiber laser at 1083 nm.

    PubMed

    Zhang, Yuanfei; Yang, Changsheng; Li, Can; Feng, Zhouming; Xu, Shanhui; Deng, Huaqiu; Yang, Zhongmin

    2016-02-22

    A linearly frequency-modulated, actively Q-switched, single-frequency ring fiber laser based on injection seeding from an ultra-short cavity is demonstrated at 1083 nm. A piezoelectric transducer is employed to obtain linearly frequency-modulating performance and over 1.05 GHz frequency-tuning range is achieved with a modulating frequency reaching tens of kilohertz. A maximum peak power of the stable output pulse is over 3.83 W during frequency-modulating process. This type of pulsed fiber laser provides a promising candidate for coherent LIDAR in the measurement of thermosphere. PMID:26906980

  20. Proton acceleration by single-cycle laser pulses offers a novel monoenergetic and stable operating regime

    NASA Astrophysics Data System (ADS)

    Zhou, M. L.; Yan, X. Q.; Mourou, G.; Wheeler, J. A.; Bin, J. H.; Schreiber, J.; Tajima, T.

    2016-04-01

    Prompted by the possibility to produce high energy, single-cycle laser pulses with tens of Petawatt (PW) power, we have investigated laser-matter interactions in the few optical cycle and ultra relativistic intensity regimes. A particularly interesting instability-free regime for ion production was revealed leading to the efficient coherent generation of short (femtosecond; 10 - 15 s ) monoenergetic ion bunches with a peak energy greater than GeV. Of paramount importance, the interaction is absent of the Rayleigh Taylor Instabilities and hole boring that plague techniques such as target normal sheath acceleration and radiation pressure acceleration.

  1. Creation and control of single attosecond XUV pulse by few-cycle intense laser pulse

    NASA Astrophysics Data System (ADS)

    Carrera, Juan J.; Tong, X. M.; Chu, Shih-I.

    2006-05-01

    We present a theoretical investigation of the mechanisms responsible for the production of single atto-second pulse by using few-cycle intense laser pulses. The atto-second XUV spectral is calculated by accurately integrating the time- dependent Schr"odinger equation. The detailed mechanism for the production of the XUV pulse are also corroborated by analyzing the classical trajectories of the electron. Our study shows that the first return of the rescattering electron is responsible for the high energy atto-second pulse. Furthermore, we can optimize the production of atto-second XUV pulses by modifying the trajectory of the rescattering electron by tuning the laser field envelope.

  2. Single shot dynamic ellipsometry mesaurements of laser-driven shock waves

    SciTech Connect

    Bolme, C. A.

    2007-12-12

    A technique has been developed to measure the time-resolved position of a laser-driven shock wave and the subsequent material flow. Ultrafast dynamic ellipsometry, using a chirped femtosecond laser pulse, probes picosecond material dynamics in a single shot by capitalizing on the refractive index changes in the shocked material. For transparent materials, the shock velocity, the particle velocity, and the shocked material's refractive index are extracted. Hugoniot data for poly(chlorotrifluoroethylene-co-vinylidene fluoride) (Kel-F 800) was obtained using ultrafast dynamic ellipsometry, and the data agrees well with previous data on macroscopic samples obtained in plate impact gas gun experiments.

  3. The free-electron laser - Maxwell's equations driven by single-particle currents

    NASA Technical Reports Server (NTRS)

    Colson, W. B.; Ride, S. K.

    1980-01-01

    It is shown that if single particle currents are coupled to Maxwell's equations, the resulting set of self-consistent nonlinear equations describes the evolution of the electron beam and the amplitude and phase of the free-electron-laser field. The formulation is based on the slowly varying amplitude and phase approximation, and the distinction between microscopic and macroscopic scales, which distinguishes the microscopic bunching from the macroscopic pulse propagation. The capabilities of this new theoretical approach become apparent when its predictions for the ultrashort pulse free-electron laser are compared to experimental data; the optical pulse evolution, determined simply and accurately, agrees well with observations.

  4. High Energy, Single-Mode, All-Solid-State Nd:YAG Laser

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.; Singh, Upendra N.; Hovis, Floyd

    2006-01-01

    In this paper, recent progress made in the design and development of an all-solid-state, single longitudinal mode, conductively cooled Nd:YAG laser operating at 1064 nm wavelength for UV lidar for ozone sensing applications is presented. Currently, this pump laser provides an output pulse energy of greater than 1.1 J/pulse at 50 Hz PRF and a pulsewidth of 22 ns. The spatial profile of the output beam is a rectangular super Gaussian. Electrical-to-optical system efficiency of greater than 7% and a minimum M(sup 2) value of less than 2 have been achieved.

  5. High-efficiency broad-area single-quantum-well lasers with narrow single-lobed far-field patterns prepared by molecular beam epitaxy

    NASA Technical Reports Server (NTRS)

    Larsson, A.; Muttelstein, M.; Arakawa, Y.; Yariv, A.

    1986-01-01

    Broad-area single-quantum-well graded-index waveguide separate-confinement heterostructure lasers were fabricated by molecular beam epitaxy. A high external quantum efficiency of 79 percent and stable, single-lobed far-field patterns with a beam divergence as narrow as 0.8 deg (1.9 times diffraction limit) for a 100 micron-wide laser were obtained under pulsed conditions.

  6. Single-frequency operation of a long-pulse e-beam excited XeF(C-A) laser

    SciTech Connect

    Klimek, D.E.; Mandl, A. )

    1994-12-01

    A 1-m gain length e-beam excited XeF(C-A) excimer laser operating in a unique re-imaging ring amplifier configuration has been used to amplify an ultranarrowband single-mode dye laser pulse. Double heterodyne detection was used to simultaneously determine the single-mode injection dye laser and the amplified XeF(C-A) laser bandwidths. Fast Fourier transform (FFT) analysis of the pulses indicates that the amplifier output has the same bandwidth as the injected dye laser pulse. The bandwidth of the XeF(C-A) laser was line narrowed by 6 orders of magnitude, from a free running value of 16 nm (20000 GHz) to 20 MHz. Specific output energies of 0.7 J/l at 488 nm and 1.3 J/l at 476.5 nm were measured. Laser output pulse lengths up to 500 ns were observed.

  7. Single-frequency, 500-ns laser pulses generated by a passively Q-switched Nd laser

    NASA Astrophysics Data System (ADS)

    Jones, D. C.; Rockwell, D. A.

    1993-03-01

    Accounts are given of the construction and performance of a narrowband Q-switched oscillator that addresses requirements for heavy amplifier saturation as well as a degree of temporal pulse-shaping prior to oscillator beam injection into the amplifier chain that can avoid the severe temporal distortion imposed by amplifier saturation. This oscillator encompasses a lamp-pumped Cr:Nd:GSGG laser rod, a saturable absorber Q switch, and several etalon surfaces forming the output coupler. This device can be used in large baseline holography.

  8. Widely continuous-tuning single-wavelength laser based on commercial multimode VCSELs

    NASA Astrophysics Data System (ADS)

    Yen, Tsu-Chiang; Hsu, Chuan-Pi; Wu, Yu-Heng; Cheng, Da-Long; Kuo, Wang-Chuang

    2010-08-01

    The conventional vertical-cavity surface-emitting lasers (VCSELs) are designed to have a very short resonant cavity. Therefore, the longitudinal mode of the VCSELs is intrinsically single; and the VCSELs are expected to be an excellent instrument for many precision measurements that demand high-purity single-wavelength light sources. However, the laser facet of the conventional VCSELs is relatively large, around 10 μm, which admits the emission of multi-transverse modes. Accordingly, conducting a single transverse mode from VCSELs is an important research topic. In this research, the beam-profile-adapted optical feedback (BPAF) method was investigated by a single-mode fiber cavity (SMFC), in which the beam profile of the multimode-VCSEL's output was adapted to the fundamental-transverse mode of an optical fiber to feedback into the laser's cavity. The operational principle and performance of BPAF will be presented. The experimental results successfully demonstrated that BPAF can efficiently conduct multimode VCSELs to stably lase the fundamental transverse mode with a wide tuning range of about 1090 GHz, or 2.62 nm, and a spectrum purity around 20 dB. Some precision spectrum measurements will be exhibited. These results will help to extend the application of the VCSELs in many precision measurements.

  9. Influence of laser conditioning on laser induced damage threshold of single layers of ZrO2 with various deposition conditions

    NASA Astrophysics Data System (ADS)

    Sahraee, M.; Reza Fallah, H.; Zabolian, H.; Moradi, B.; Haji Mahmoodzade, M.

    2015-04-01

    Single layers of ZrO2 were coated at base pressure of 10-5 mbar by electron beam evaporation (EBE) technique. The influence of oxygen partial pressure on spectral properties and laser induced damage threshold (LIDT) of the samples were investigated. Spectral transmittance of the samples was measured by spectrophotometer. Laser induced damage threshold was detected according to ISO standard 11254. Laser conditioning was conducted by scanning the surface of the samples. Results showed that laser damage resistance was enhanced by increasing the oxygen partial pressure during deposition. LIDT of the samples was changed after laser conditioning. Experimental results revealed that there is enhancement of laser damage resistance of the samples with higher oxygen partial pressure after laser conditioning.

  10. Effect of a short weak prepulse on laser-triggered front-surface heavy-ion acceleration

    SciTech Connect

    Bochkarev, S. G.; Bychenkov, V. Yu.; Golovin, G. V.; Uryupina, D. S.; Shulyapov, S. A.; Savel'ev, A. B.; Andriyash, A. V.

    2012-10-15

    A suppression of light-ion acceleration (from surface water contaminants) was observed when a moderate-intensity subpicosecond laser pulse was focused on a thick metal target. Simultaneously, an effective generation of high-energy multicharge ions of the target material (Fe) was experimentally observed. A numerical simulation based on the Boltzmann-Vlasov-Poisson model revealed that this is due to the very specific regime of cleaning contaminants from the target surface by the short weak prepulse preceding the main pulse by more than 10 ns and having an intensity below the surface breakdown threshold. Because this prepulse causes the contaminant layer to boil explosively, a low-density gap forms above the target surface. These conditions are consequently favorable for boosting the energy of heavy ions.

  11. Water Encapsulation Control in Individual Single-Walled Carbon Nanotubes by Laser Irradiation.

    PubMed

    Chiashi, Shohei; Hanashima, Tateki; Mitobe, Ryota; Nagatsu, Kotaro; Yamamoto, Takahiro; Homma, Yoshikazu

    2014-02-01

    Owing to one-dimensionality, nanoscale curvature, and high chemical stability, single-walled carbon nanotubes (SWNTs) have unique surfaces for gas molecules: outer surface as adsorption (exohedral) site and inner surface that provides encapsulation (endohedral) space. Because as-grown SWNTs have different structure (chirality and diameter) and they are normally bundled, it is extremely difficult to investigate the intrinsic properties of SWNTs as adsorbent. Here we demonstrate controlling adsorption and encapsulation states of water in individual suspended SWNTs using laser irradiation with monitoring of their behavior by photoluminescence measurement and perform molecular dynamics simulation. The laser heating and the pressure control make water molecules encapsulated or ejected for SWNTs, which are individually oxidized and opened with laser heating. The precise control of oxidization makes it possible to observe the cluster formation of water molecules during the encapsulation process and to confine water molecules inside SWNTs even in vacuum. PMID:26276583

  12. Efficient single-cell transgene induction in Caenorhabditis elegans using a pulsed infrared laser.

    PubMed

    Churgin, Matthew A; He, Liping; Murray, John I; Fang-Yen, Christopher

    2013-10-01

    The coupling of transgenes to heat shock promoters is a widely applied method for regulating gene expression. In C. elegans, gene induction can be controlled temporally through timing of heat shock and spatially via targeted rescue in heat shock mutants. Here, we present a method for evoking gene expression in arbitrary cells, with single-cell resolution. We use a focused pulsed infrared laser to locally induce a heat shock response in specific cells. Our method builds on and extends a previously reported method using a continuous-wave laser. In our technique, the pulsed laser illumination enables a much higher degree of spatial selectivity because of diffusion of heat between pulses. We apply our method to induce transient and long-term transgene expression in embryonic, larval, and adult cells. Our method allows highly selective spatiotemporal control of transgene expression and is a powerful tool for model organism biology. PMID:23979939

  13. Optimizing the performance of single-mode laser diode system using genetic algorithm

    NASA Astrophysics Data System (ADS)

    Aydin, Elif; Yildirim, Remzi

    2004-07-01

    In this correspondence, micro-genetic algorithm (MGA) application results for optimizing the performance of electronic feedback of a laser diode are presented. The goal of optimization is to find the maximum bandwidth of the laser diode with electronic feedback used in fiber optic digital communication. A numerical analysis of the system theory of the single-mode laser diode to obtain numerical results of the gain, the pulse response, and the harmonic distortion for electronic feedback is also presented. The dependence of the system gain on the feedback gain and delay is examined. The pulse response is studied and it is shown that a transmission rate over 1 Gbyte/s can be achieved.

  14. Experimental study on the single event effects in pulse width modulators by laser testing

    NASA Astrophysics Data System (ADS)

    Wen, Zhao; Xiaoqiang, Guo; Wei, Chen; Hongxia, Guo; Dongsheng, Lin; Hanning, Wang; Yinhong, Luo; Lili, Ding; Yuanming, Wang

    2015-11-01

    This paper presents single event effect (SEE) characteristics of UC1845AJ pulse width modulators (PWMs) by laser testing. In combination with analysis to map PWM circuitry in the microchip dies, the typical SEE response waveforms for laser pulses located in different circuit blocks of UC1845AJ are obtained and the SEE mechanisms are analyzed. The laser SEE test results show that there are some differences in the SEE mechanisms of different circuit blocks, and phase shifts or changes in the duty cycles of few output pulses are the main SEE behaviors for UC1845AJ. In addition, a new SEE behavior which manifests as changes in the duty cycles of many output pulses is revealed. This means that an SEE hardened design should be considered.

  15. Single-frequency diode-pumped lasers for free-space optical communication

    NASA Technical Reports Server (NTRS)

    Kane, Thomas J.; Cheng, Emily A. P.; Gerstenberger, David C.; Wallace, Richard W.

    1990-01-01

    Recent advances in laser technology for intersatellite optical communication systems are reviewed and illustrated with graphs and diagrams. Topics addressed include (1) single-frequency diode-pumped Nd:YAG lasers of monolithic ring configuration (yielding 368-384 mW output power with 1-W pumping), (2) injection chaining of up to 10 monolithic resonators to achieve redundancy and/or higher output power, (3) 2-kHz-linewidth 5-mW versions of (1) which are tunable over a 30-MHz range for use as local oscillators in coherent communication, (4) resonant external modulation and doubling or resonant phase modulation of diode-pumped lasers, and (5) wavelength multiplexing.

  16. Low-dissipation 7.4-µm single-mode quantum cascade lasers without epitaxial regrowth.

    PubMed

    Briggs, Ryan M; Frez, Clifford; Fradet, Mathieu; Forouhar, Siamak; Blanchard, Romain; Diehl, Laurent; Pflügl, Christian

    2016-06-27

    We report continuous-wave operation of single-mode quantum cascade (QC) lasers emitting near 7.4 µm with threshold power consumption below 1 W at temperatures up to 40 °C. The lasers were fabricated with narrow, plasma-etched waveguides and distributed-feedback sidewall gratings clad with sputtered aluminum nitride. In contrast to conventional buried-heterostructure (BH) devices with epitaxial sidewall cladding and in-plane gratings, the devices described here were fabricated without any epitaxial regrowth processes, yet they exhibit power consumption comparable to the lowest-dissipation BH QC lasers reported to date. These low-dissipation devices are designed primarily as light sources for infrared spectroscopy instruments with limited volume, mass, and power budgets. PMID:27410611

  17. Smart bombing a single targeted cell with femtogram order reagents using laser-induced shockwave technique

    NASA Astrophysics Data System (ADS)

    Okano, Kazunori; Takizawa, Noriko; Uwada, Takayuki; Hosokawa, Yoichiroh; Masuhara, Hiroshi

    2008-02-01

    Injection and delivery of small amount reagent in aqueous solution for cell chip was performed utilizing regeneratively amplified femtosecond laser system. In our new trial, the reagent integrated on a solid strip are released and delivered to targeted cells with the femutosecond laser-induced impulsive-force. The reagent was fixed in poly(vinyl alcohol) or polystyrene film on a glass-substrate strip. When a single pulsed femtosecond laser was focused in the solution, the film near the focal point was fragmented and the reagent was dispersed in 45-μm φ area at 50 μm from the surface of the reagent strip. As examples cardiomyocyte beating cells of P19CL6 were bombed with epinephrine and acetylcholine, and as a result the beating ratio of the cells were quickly stimulated and suppressed, respectively. The results demonstrate that the present method is a promising key nano/micro technology for diagnosis and drug discovery.

  18. Single mode 1018nm fiber laser with power of 230W

    NASA Astrophysics Data System (ADS)

    Glick, Yaakov; Sintov, Yoav; Zuitlin, Roey; Pearl, Shaul; Feldman, Revital; Horvitz, Zvi; Shafir, Noam

    2016-03-01

    We have developed a high power single-mode (SM) monolithic fiber laser at 1018 nm, producing 230 W CW, with an M2 of 1.17 and light to light efficiency of 75%. To the best of our knowledge this is the highest power described in the open literature from a SM fiber laser at this wavelength. Careful simulations were employed which take into account the various wavelength dependent parameters such as the fiber absorption and emission as obtained from the fiber manufacturers, and the cavity mirrors' reflection, in addition to the fiber geometrical parameters. It was found that the major obstacle for increasing the power at 1018nm is the self-generation of amplified spontaneous emission at wavelengths of 1030-1040nm. If the laser is not designed properly these undesired wavelengths dominate the output spectrum.

  19. Rear surface spallation on single-crystal silicon in nanosecond laser micromachining

    NASA Astrophysics Data System (ADS)

    Ren, Jun; Orlov, Sergei S.; Hesselink, Lambertus

    2005-05-01

    Rear surface spallation of single-crystal silicon under 5-ns laser pulse ablation at intensities of 0.6-60GW/cm2 is studied through postablation examination of the ablated samples. The spallation threshold energy and the spallation depth's dependences on the energy and target thickness are measured. From the linear relation between the spallation threshold energy and the target thickness, an estimation of the material spall strength around 1.4GPa is obtained, in reasonable agreement with the spall strength estimation of 0.8-1.2GPa at a strain rate of 107s-1 using Grady's model for brittle materials. The experiment reveals the internal fracturing process over an extended zone in silicon, which is controlled by the competition between the shock pressure load and the laser ablation rate. The qualities of the laser microstructuring and micromachining results are greatly improved by using an acoustic impedance matching approach.

  20. A rut measuring method based on laser triangulation with single camera

    NASA Astrophysics Data System (ADS)

    Ma, Yue; Zhang, Wen-hao; Li, Song; Wang, Hong

    2013-12-01

    Pavement rut is one of the major highway diseases. In this article, the method of measuring rut based on laser triangulation is created. The rut-resolution model is established to design the parameters of optical system and the laser profile of road image was extracted by median filter and wavelet transform. An accurate calibration method on large field of view consisting of 28 sub-FOVs calibration and road profile reconstruction is also created. The process of calibration experiment and a new calculation method of rut is described. The measurement results were showed, which concluded the static test of gauge block and the dynamic measurement on highway. The conclusion is with this method using single CCD camera and two semiconductor laser of 808nm wavelength can reach the accuracy of 1mm on rut measurement in tough circumstance.

  1. Short monolithic dual-wavelength single-longitudinal-mode DBR phosphate fiber laser.

    PubMed

    Xiong, Lingyun; Hofmann, Peter; Schülzgen, Axel; Peyghambarian, N; Albert, Jacques

    2014-06-20

    We propose and demonstrate a 5-cm-long monolithic dual-wavelength single-longitudinal mode distributed Bragg reflector (DBR) all-phosphate fiber laser. Strong UV-induced fiber Bragg gratings are directly written in highly Er/Yb codoped phosphate fiber. The separation between gratings is selected as 1 cm to only excite two longitudinal modes in the DBR cavity. By exploiting the spatial hole burning effect and the polarization hole burning effect, stable narrow-linewidth dual-wavelength lasing emission with 38 pm wavelength spacing and a total emitted power of 2.8 mW is obtained from this DBR fiber laser. A microwave signal at 4.58 GHz is generated by the heterodyne detection of the dual-wavelength laser. PMID:24979414

  2. Fabrication and spectral tuning of standing gold infrared antennas using single fs-laser pulses.

    PubMed

    Reininghaus, Martin; Wortmann, Dirk; Cao, Zhao; Hoffmann, Jón Mattis; Taubner, Thomas

    2013-12-30

    Upright standing gold monopole nanoantennas are fabricated by irradiation of thin gold films with single pulses of fs-laser radiation. The resulting antennas exhibit extinction resonances in the mid infrared spectral rage for p-polarized light under grazing incidence. Due to the free charge carriers in the surrounding gold film of the antenna, the resonance condition of the thin-wire monopole antenna can be explained by introducing image charges yielding an observable resonance wavelength of four times the antenna length. The antenna length is controlled coarsely by the focusing numerical aperture and fine by the pulse energy of the laser pulse producing the structure. An additional ultrafine tuning of the resonance wavelength with a sub-10 nm resolution is realized by an additional coating process subsequent to the laser structuring. PMID:24514811

  3. Crystal growth, spectral and laser properties of Nd:LSAT single crystal

    NASA Astrophysics Data System (ADS)

    Hu, P. C.; Yin, J. G.; Zhao, C. C.; Gong, J.; He, X. M.; Zhang, L. H.; Liang, X. Y.; Hang, Y.

    2011-10-01

    Nd:(La, Sr)(Al, Ta)O3 (Nd:LSAT) crystal was grown by the Czochralski method. The absorption and fluorescence spectra of Nd:LSAT crystal at room temperature were investigated. With a fiber-coupled diode laser as pump source, the continuous-wave (CW) laser action of Nd:LSAT crystal was demonstrated. The result of diode-pumped laser operation of Nd:LSAT crystal single crystal is reported for what is to our knowledge the first time. The maximum output power at 1064 nm was obtained to be 165 mW under the incident pump power of 3 W, with the slope efficiency 10.9%.

  4. Selective mode coupling in microring resonators for single mode semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Arbabi, Amir

    Single mode semiconductor laser diodes have many applications in optical communications, metrology and sensing. Edge-emitting single mode lasers commonly use distributed feedback structures, or narrowband reflectors such as distributed Bragg reflectors (DBRs) and sampled grating distributed Bragg reflectors (SGDBRs). Compact, narrowband reflectors with high reflectivities are of interest to replace the commonly used DBRs and SGDBRs. This thesis presents our work on the simulation, design, fabrication, and characterization of devices operating based on the coupling of degenerate modes of a microring resonator, and investigation of the possibility of using them for improving the performance of laser diodes. In particular, we demonstrate a new type of compact, narrowband, on-chip reflector realized by selectively coupling degenerate modes of a microring resonator. For the simulation and design of reflective microring resonators, a fast and accurate analysis method is required. Conventional numerical methods for solving Maxwell's equations such as the finite difference time domain and the finite element method (FEM) provide accurate results but are computationally intense and are not suitable for the design of large 3D structures. We formulated a set of coupled mode equations that, combined with 2D FEM simulations, can provide a fast and accurate tool for the modeling and design of reflective microrings. We developed fabrication processing recipes and fabricated passive reflective microrings on silicon substrates with a silicon nitride core and silicon dioxide cladding. Narrowband single wavelength reflectors were realized which are 70 times smaller than a conventional DBR with the same bandwidth. Compared to the conventional DBR, they have faster roll-off, and no side modes. The smaller footprint saves real estate, reduces tuning power and makes these devices attractive as in-line mirrors for low threshold narrow linewidth laser diodes. Self-heating caused by material

  5. Direct writing of continuous and discontinuous sub-wavelength periodic surface structures on single-crystalline silicon using femtosecond laser

    SciTech Connect

    Kuladeep, Rajamudili; Sahoo, Chakradhar; Narayana Rao, Desai E-mail: dnr-laserlab@yahoo.com

    2014-06-02

    Laser-induced ripples or uniform arrays of continuous near sub-wavelength or discontinuous deep sub-wavelength structures are formed on single-crystalline silicon (Si) by femtosecond (fs) laser direct writing technique. Laser irradiation was performed on Si wafers at normal incidence in air and by immersing them in dimethyl sulfoxide using linearly polarized Ti:sapphire fs laser pulses of ∼110 fs pulse duration and ∼800 nm wavelength. Morphology studies of laser written surfaces reveal that sub-wavelength features are oriented perpendicular to laser polarization, while their morphology and spatial periodicity depend on the surrounding dielectric medium. The formation mechanism of the sub-wavelength features is explained by interference of incident laser with surface plasmon polaritons. This work proves the feasibility of fs laser direct writing technique for the fabrication of sub-wavelength features, which could help in fabrication of advanced electro-optic devices.

  6. Wavelength tunable high-power single-mode 1060-nm DBR lasers

    NASA Astrophysics Data System (ADS)

    Li, Jin; Kuksenkov, Dmitri V.; Liu, Wayne; Li, Yabo; Visovsky, Nick J.; Pikula, Dragan; Heberle, Albert P.; Brown, Gordon C.; Piech, Garrett A.; Butler, Douglas L.; Zah, Chung-en

    2012-03-01

    The wavelength tunable 1060-nm distributed Bragg reflector (DBR) laser chip consists of three sections: a gain section for lasing, and phase and DBR sections for wavelength control. A micro-heater is lithographically integrated on the top of the DBR section to tune the emission wavelength. The phase section is designed with either a top heater or by current injection to provide fine tuning of the wavelength. The wavelength tuning efficiency of our DBR laser is approximately 9 nm/W at the laser heat sink temperature of 25°C. Single-mode output powers of 686 mW and 605 mW were obtained at a CW gain drive current of 1.25 A and heat sink temperatures of 25°C and 60°C, respectively. Gain-switching by applying 1.1 GHz sinusoidal signal mixed with 600 mA DC injection current produced approximately 58 ps long optical pulses with 3.1 W peak power and 228 mW average power. The average power increased to 267 mW and pulse width broadened to 70 ps with DC bias of 700 mA. In CW operation, one of the applications for high-power single-mode DBR lasers is for non-linear frequency conversion. The light emitted from the 1060-nm DBR laser chip was coupled into a single-mode periodically poled lithium niobate (PPLN) crystal waveguide. Up to 350 mW optical power at 530 nm with the wall-plug efficiency of up to 15% was demonstrated.

  7. Single- and multi-wavelength laser operation of a diode-pumped ND:GGG single crystal around 1.33 μm

    NASA Astrophysics Data System (ADS)

    Xu, Bin; Wang, Yi; Cheng, Yongjie; Xu, Huiying; Cai, Zhiping; Moncorgé, Richard

    2015-06-01

    We report on the first continuous-wave laser operation of a diode-pumped Nd:GGG single crystal at several emission wavelengths in the 1.33 μm spectral domain. Multi-wavelength laser operation at 1324, 1331 and 1337 nm with a maximum laser output power of 1.83 W and a laser slope efficiency of 28.9% for an output coupler transmission of 2.2% is obtained in the free-running regime. By inserting and tilting a 0.1-mm BK7 glass etalon to modulate the losses inside the laser cavity, single wavelength lasing at 1324 nm and 1347 nm are also achieved with maximum output powers of about 0.77 W and 0.41 W as well as laser slope efficiencies of 15.2% and 12.6%, respectively. Further increasing the pump power, based on the position of the etalon leading to the single laser wavelength operation at 1347 nm, stable dual-wavelength laser operation is demonstrated at 1337 and 1347 nm with a maximum output power of 0.61 W.

  8. Femtosecond laser fabricated integrated chip for manipulation of single cells (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Keloth, Anusha; Jimenez, Melanie; Bridle, H.; Paterson, Lynn; Markx, Gerard H.; Kar, Ajoy K.

    2016-03-01

    Optical micromanipulation techniques and microfluidic techniques can be used in same platform for manipulating biological samples at single cell level. Novel microfluidic devices with integrated channels and waveguides fabricated using ultrafast laser inscription combined with selective chemical etching can be used to enable sorting and isolation of biological cells. In this paper we report the design and fabrication of a three dimensional chip that can be used to manipulate single cells in principle with a higher throughput than is possible using optical tweezers. The capability of ultrafast laser inscription followed by selective chemical etching to fabricate microstructures and waveguides have been utilised to fabricate the device presented in this paper. The complex three dimensional microfluidic structures within the device allow the injected cell population to focus in a hydrodynamic flow. A 1064 nm cw laser source, coupled to the integrated waveguide, is used to exert radiation pressure on the cells to be manipulated. As the cells in the focussed stream flow past the waveguide, optical scattering force induced by the laser beam pushes the cell from out of the focussed stream to the sheath fluid, which can be then collected at the outlet. Thus cells can be controllably deflected from the focussed flow to the side channel for downstream analysis or culture.

  9. Continuous-wave single-frequency laser with dual wavelength at 1064 and 532 nm.

    PubMed

    Zhang, Chenwei; Lu, Huadong; Yin, Qiwei; Su, Jing

    2014-10-01

    A continuous-wave high-power single-frequency laser with dual-wavelength output at 1064 and 532 nm is presented. The dependencies of the output power on the transmission of the output coupler and the phase-matching temperature of the LiB(3)O(5) (LBO) crystal are studied. An output coupler with transmission of 19% is used, and the temperature of LBO is controlled to the optimal phase-matching temperature of 422 K; measured maximal output powers of 33.7 W at 1064 nm and of 1.13 W at 532 nm are obtained with optical-optical conversion efficiency of 45.6%. The laser can be single-frequency operated stably and mode-hop-free, and the measured frequency drift is less than 15 MHz in 1 min. The measured Mx2 and My2 for the 1064 nm laser are 1.06 and 1.09, respectively. The measured Mx2 and My2 for the 532 nm laser are 1.12 and 1.11, respectively. PMID:25322220

  10. High Energy, Single-Mode, All-Solid-State and Tunable UV Laser Transmitter

    NASA Technical Reports Server (NTRS)

    Prasad, Narasimha S.; Singh, Upendra N.; Hovis, FLoyd

    2007-01-01

    A high energy, single mode, all solid-state Nd:YAG laser primarily for pumping an UV converter is developed. Greater than 1 J/pulse at 50 HZ PRF and pulse widths around 22 ns have been demonstrated. Higher energy, greater efficiency may be possible. Refinements are known and practical to implement. Technology Demonstration of a highly efficient, high-pulse-energy, single mode UV wavelength generation using flash lamp pumped laser has been achieved. Greater than 90% pump depletion is observed. 190 mJ extra-cavity SFG; IR to UV efficiency > 21% (> 27% for 1 mJ seed). 160 mJ intra-cavity SFG; IR to UV efficiency up to 24% Fluence < 1 J/sq cm for most beams. The pump beam quality of the Nd:YAG pump laser is being refined to match or exceed the above UV converter results. Currently the Nd:YAG pump laser development is a technology demonstration. System can be engineered for compact packaging.

  11. Cost-effective design of a concurrent photoacoustic-ultrasound microscope using single laser pulses

    NASA Astrophysics Data System (ADS)

    Wu, Wen-Shao; Liu, Wei-Wen; Li, Pai-Chi

    2016-03-01

    A method for concurrent photoacoustic (PA) and ultrasound (US) imaging with single laser pulses was previously demonstrated. An optical-absorbing multilayer film that can generate a US pulse based on the thermoelastic effect is used. With such a film, the generated US can be adjusted so that it does not overlap with the spectrum of the PA signal generated by the light transmitting through the layer. Thus, the US signal and the PA signal can be generated and separated by using a single laser pulse with spectral filtering. In this study, we continue with the same concurrent imaging approach and propose a cost-effective and portable design. The design consists of a pulsed laser diode with the repetition rate up to 25 kHz and energy of 2 μJ/pulse. A multilayer film is employed to generate narrow band US signals under laser excitation for US imaging. With simple spectral filtering, the PA signals and the US signals can be separated. With optical resolution, the system has a theoretical lateral resolution of 2 μm in PA imaging and 200 μm in US imaging. One of the applications of the proposed microscope is for tumor biology, where angiogenesis is an essential topic for understanding tumor growth and tumor metastasis. We will demonstrate performance of the proposed system by imaging vasculature networks.

  12. Single-mode tapered terahertz quantum cascade lasers with lateral gratings

    NASA Astrophysics Data System (ADS)

    Yao, C.; Xu, T. H.; Wan, W. J.; Li, H.; Cao, J. C.

    2016-08-01

    We report on tapered terahertz quantum cascade lasers with lateral gratings. The proposed devices exhibit not only low horizontal divergence due to tapered structure but also single-mode operation by using lateral grating structure. The tapered region and lateral gratings can be fabricated with the ridged waveguide in one etching step without inducing complexity into the fabrication. Side-mode suppression ratio ∼20 dB is obtained for proposed devices from threshold to rollover currents at all measure temperatures, with the peak output power of ∼30 mW at 10 K in pulsed mode and lateral divergence angle reduced by half. The proposed devices are good candidates for high-power, single-mode operation and low-divergence laser with easy fabrication.

  13. High peak-power kilohertz laser system employing single-stage multi-pass amplification

    DOEpatents

    Shan, Bing; Wang, Chun; Chang, Zenghu

    2006-05-23

    The present invention describes a technique for achieving high peak power output in a laser employing single-stage, multi-pass amplification. High gain is achieved by employing a very small "seed" beam diameter in gain medium, and maintaining the small beam diameter for multiple high-gain pre-amplification passes through a pumped gain medium, then leading the beam out of the amplifier cavity, changing the beam diameter and sending it back to the amplifier cavity for additional, high-power amplification passes through the gain medium. In these power amplification passes, the beam diameter in gain medium is increased and carefully matched to the pump laser's beam diameter for high efficiency extraction of energy from the pumped gain medium. A method of "grooming" the beam by means of a far-field spatial filter in the process of changing the beam size within the single-stage amplifier is also described.

  14. Single Frequency Monolithic Solid State Green Laser as a Potential Source for Vibrometry Systems

    SciTech Connect

    Sotor, Jaroslaw Z.; Antonczak, Arkadiusz J.; Abramski, Krzysztof M.

    2010-05-28

    In this paper miniature, monolithic single frequency solid state laser operating at 532 nm is presented. Developed Nd:GdVO{sub 4}/YVO{sub 4}/KTP consist of three crystal bonded together with a UV adhesive. The single frequency operation was obtained in wide temperature range from 17 deg. C to 27 deg. C. The laser operated with output power up to 90 mW at 532 nm. The total optical efficiency (808 nm to 532 nm) was 9.5%. Power stability was at the level of +-0.8% and the long term frequency stability was approximately 3centre dot10{sup -8}. The beam has a Gaussian profile and the M2 parameter was below 1.1.

  15. Single Frequency, Pulsed Laser Diode Transmitter for Dial Water Vapor Measurements at 935nm

    NASA Technical Reports Server (NTRS)

    Switzer, Gregg W.; Cornwell, Donald M., Jr.; Krainak, Michael A.; Abshire, James B.; Rall, Johnathan A. R.

    1998-01-01

    We report a tunable, single frequency, narrow linewidth, pulsed laser diode transmitter at 935.68nm for remote sensing of atmospheric water vapor. The transmitter consists of a CW, tunable, external cavity diode laser whose output is amplified 2OdB using a tapered diode amplifier. The output is pulsed for range resolved DIAL lidar by pulsing the drive current to the diode amplifier at 4kHz with a .5% duty cycle. The output from the transmitter is 36OnJ/pulse and is single spatial mode. It maintains a linewidth of less than 25MHz as its wavelength is tuned across the water vapor absorption line at 935.68nm. The transmitter design and its use in a water vapor measurement will be discussed.

  16. Semiclassical theory of dye lasers: the single-frequency and multifrequency steady states of operation

    SciTech Connect

    Fu, H.; Haken, H.

    1988-05-01

    A semiclassical theory of dye lasers is presented in which the relevant energy-level diagram of a dye molecule is assumed to consist of a bandlike ground state with many sublevels and an excited single state. This theory not only describes the single-frequency operation, which has a low instability threshold, but also describes the two-frequency and multifrequency steady states of operation and the transitions between the different steady states. The general solution of a multifrequency operation is given explicitly and differs essentially from the well-known Rabi oscillation. The theoretical predictions are in good agreement with recent experiments done by Hillman et al. (Phys. Rev. Lett. 52, 1605 (1984)), which cannot be explained by the conventional Maxwell--Bloch laser theory derived from two-level atoms.

  17. Optical trap for both transparent and absorbing particles in air using a single shaped laser beam.

    PubMed

    Redding, Brandon; Pan, Yong-Le

    2015-06-15

    Optical trapping of airborne particles is emerging as an essential tool in applications ranging from online characterization of living cells and aerosols to particle transport and delivery. However, existing optical trapping techniques using a single laser beam can trap only transparent particles (via the radiative pressure force) or absorbing particles (via the photophoretic force), but not particles of either type-limiting the utility of trapping-enabled aerosol characterization techniques. Here, we present the first optical trapping technique capable of trapping both transparent and absorbing particles with arbitrary morphology using a single shaped laser beam. Such a general-purpose optical trapping mechanism could enable new applications such as trapping-enabled aerosol characterization with high specificity. PMID:26076265

  18. Phase transition in photo-absorbing single microemulsion droplets during the laser photophoretic migration

    NASA Astrophysics Data System (ADS)

    Monjushiro, Hideaki; Tanaka, Makiko; Watarai, Hitoshi

    2005-08-01

    Laser-photophretic behavior of the micrometer-sized single droplets of photo-absorbing microemulsion was observed in water by irradiating a cw Ar+ ion laser. We have made an unexpected observation that the droplets repeated the expansion and the sudden contraction motion during the laser photophoretic migration. The period of the expansion-contraction cycle was decreased as the irradiated laser power was increased and was independent of the initial size of the droplet. The origin of the cyclical motion is the temperature rise of the droplet due to the photo-thermal conversion. The three-step mechanism for the periodic motion of the droplet was proposed. The first step is the phase separation of the bicontinuous microemulsion droplet into the normal w/o microemulsion outer phase and the aqueous inner phase in the droplet, which was caused by the laser-induced temperature gradient inside the droplet. In the second step, an expansion of the inner aqueous phase was induced by the percolation of the external water by thermo-osmosis, which was caused by the laser-induced temperature gradient between inside and outside of the microemulsion liquid membrane of the droplet. In the third step, the liquid membrane became thinner to a critical thickness which induced its break and the droplet shrank into the original shape. The proposed mechanism for the expansion process was confirmed by the numerical simulation of the volume change of the droplet during the laser irradiation, taking account of the heat evolution in the droplet, the heat transfer from the droplet, and the percolation of the external water by thermo-osmosis and by the high-speed CCD imaging of the contraction motion of the droplet.

  19. Single-step synthesis of graphene quantum dots by femtosecond laser ablation of graphene oxide dispersions.

    PubMed

    Russo, Paola; Liang, Robert; Jabari, Elahe; Marzbanrad, Ehsan; Toyserkani, Ehsan; Zhou, Y Norman

    2016-04-21

    In the last few years, graphene quantum dots (GQDs) have attracted the attention of many research groups for their outstanding properties, which include low toxicity, chemical stability and photoluminescence. One of the challenges of GQD synthesis is finding a single-step, cheap and sustainable approach for synthesizing these promising nanomaterials. In this study, we demonstrate that femtosecond laser ablation of graphene oxide (GO) dispersions could be employed as a facile and environmentally friendly synthesis method for GQDs. With the proper control of laser ablation parameters, such as ablation time and laser power, it is possible to produce GQDs with average sizes of 2-5 nm, emitting a blue luminescence at 410 nm. We tested the feasibility of the synthesized GQDs as materials for electronic devices by aerosol-jet printing of an ink that is a mixture of water dispersion of laser synthesized GQDs and silver nanoparticle dispersion, which resulted in lower resistivity of the final printed patterns. Preliminary results showed that femtosecond laser synthesized GQDs can be mixed with silver nanoparticle dispersion to fabricate a hybrid material, which can be employed in printing electronic devices by either printing patterns that are more conductive and/or reducing costs of the ink by decreasing the concentration of silver nanoparticles (AgNPs) in the ink. PMID:27071944

  20. Resonant ablation of single-wall carbon nanotubes by femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Arutyunyan, N. R.; Komlenok, M. S.; Kononenko, V. V.; Pashinin, V. P.; Pozharov, A. S.; Konov, V. I.; Obraztsova, E. D.

    2015-01-01

    The thin 50 nm film of bundled arc-discharge single-wall carbon nanotubes was irradiated by femtosecond laser pulses with wavelengths 675, 1350 and 1745 nm corresponding to the absorption band of metallic nanotubes E11M, to the background absorption and to the absorption band of semiconducting nanotubes E11S, respectively. The aim was to induce a selective removal of nanotubes of specific type from the bundled material. Similar to conducted thermal heating experiments, the effect of laser irradiation results in suppression of all radial breathing modes in the Raman spectra, with preferential destruction of the metallic nanotubes with diameters less than 1.26 nm and of the semiconducting nanotubes with diameters 1.36 nm. However, the etching rate of different nanotubes depends on the wavelength of the laser irradiation. It is demonstrated that the relative content of nanotubes of different chiralities can be tuned by a resonant laser ablation of undesired nanotube fraction. The preferential etching of the resonant nanotubes has been shown for laser wavelengths 675 nm (E11M) and 1745 nm (E11S).

  1. Long-lasting transcriptional refractoriness triggered by a single exposure to 1-methyl-4-phenyl-1,2,3,6-tetrahydropyrimidine.

    PubMed

    Pattarini, R; Rong, Y; Shepherd, K R; Jiao, Y; Qu, C; Smeyne, R J; Morgan, J I

    2012-07-12

    Parkinson's disease (PD) is a progressive neurodegenerative disorder whose etiology is thought to have environmental (toxin) and genetic contributions. The neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyrimidine (MPTP) induces pathological features of PD including loss of dopaminergic neurons in the substantia nigra pars compacta (SNpc) and striatal dopamine (DA) depletion. We previously described the striatal transcriptional response following acute MPTP administration in MPTP-sensitive C57BL/6J mice. We identified three distinct phases: early (5h), intermediate (24h) and late (72h) and reported that the intermediate and late responses were absent in MPTP-resistant Swiss-Webster (SWR) mice. Here we show that C57BL/6J mice pre-treated with a single 40 mg/kg dose of MPTP and treated 9 days later with 4×20 mg/kg MPTP, display a striatal transcriptional response similar to that of MPTP-resistant SWR mice, i.e. a robust acute response but no intermediate or late response. Transcriptional refractoriness is dependent upon the dose of the priming challenge with as little as 10mg/kg MPTP being effective and can persist for more than 28 days. Priming of SWR mice has no effect on their response to subsequent challenge with MPTP. We also report that paraquat, another free radical producer, also elicits striatal transcriptional alterations but these are largely distinct from those triggered by MPTP. Paraquat-induced changes are also refractory to priming with paraquat. However neither paraquat nor MPTP elicits cross-attenuation. Thus exposure to specific toxins triggers distinct transcriptional responses in striatum that are influenced by prior exposure to the same toxin. The prolonged refractory period described here for MPTP could explain at the molecular level the reported discrepancies between different MPTP administration regimens and may have implications for our understanding of the relationship between environmental toxin exposure and PD. PMID:22542874

  2. A Highly-Conserved Single-Stranded DNA-Binding Protein in Xanthomonas Functions as a Harpin-Like Protein to Trigger Plant Immunity

    PubMed Central

    Che, Yi-Zhou; Zou, Li-Fang; Zakria, Muhammad; Zou, Hua-Song; Chen, Gong-You

    2013-01-01

    Harpins are produced by Gram-negative phytopathogenic bacteria and typically elicit hypersensitive response (HR) in non-host plants. The characterization of harpins in Xanthomonas species is largely unexplored. Here we demonstrate that Xanthomonas produce a highly conserved single-stranded DNA-binding protein (SSBX) that elicits HR in tobacco as by harpin Hpa1. SSBX, like Hpa1, is an acidic, glycine-rich, heat-stable protein that lacks cysteine residues. SSBX-triggered HR in tobacco, as by Hpa1, is characterized by the oxidative burst, the expression of HR markers (HIN1, HSR203J), pathogenesis-related genes, and callose deposition. Both SSBX- and Hpa1-induced HRs can be inhibited by general metabolism inhibitors actinomycin D, cycloheximide, and lanthanum chloride. Furthermore, those HRs activate the expression of BAK1 and BIK1 genes that are essential for induction of mitogen-activated protein kinase (MAPK) and salicylic acid pathways. Once applied to plants, SSBX induces resistance to the fungal pathogen Alternaria alternata and enhances plant growth. When ssbX was deleted in X. oryzae pv. oryzicola, the causal agent of bacterial leaf streak in rice, the resulting ssbXoc mutant was reduced in virulence and bacterial growth in planta, but retained its ability to trigger HR in tobacco. Interestingly, ssbXoc contains an imperfect PIP-box (plant-inducible promoter) and the expression of ssbXoc is regulated by HrpX, which belongs to the AraC family of transcriptional activators. Immunoblotting evidence showed that SSBx secretion requires a functional type-III secretion system as Hpa1 does. This is the first report demonstrating that Xanthomonas produce a highly-conserved SSBX that functions as a harpin-like protein for plant immunity. PMID:23418541

  3. Triggering Klystrons

    SciTech Connect

    Stefan, Kelton D.; /Purdue U. /SLAC

    2010-08-25

    To determine if klystrons will perform to the specifications of the LCLS (Linac Coherent Light Source) project, a new digital trigger controller is needed for the Klystron/Microwave Department Test Laboratory. The controller needed to be programmed and Windows based user interface software needed to be written to interface with the device over a USB (Universal Serial Bus). Programming the device consisted of writing logic in VHDL (VHSIC (Very High Speed Integrated Circuits) hardware description language), and the Windows interface software was written in C++. Xilinx ISE (Integrated Software Environment) was used to compile the VHDL code and program the device, and Microsoft Visual Studio 2005 was used to compile the C++ based Windows software. The device was programmed in such a way as to easily allow read/write operations to it using a simple addressing model, and Windows software was developed to interface with the device over a USB connection. A method of setting configuration registers in the trigger device is absolutely necessary to the development of a new triggering system, and the method developed will fulfill this need adequately. More work is needed before the new trigger system is ready for use. The configuration registers in the device need to be fully integrated with the logic that will generate the RF signals, and this system will need to be tested extensively to determine if it meets the requirements for low noise trigger outputs.

  4. Long-term stabilization of single longitudinal mode in external cavity semiconductor lasers

    SciTech Connect

    Zhang Hanyi; Zhou Jianying; Wu Yuanxing; Li Jian; Pang Zhengwu; Zhou Bingkun

    1988-05-01

    Long-term frequency stabilization of a single longitudinal mode (SLM) external cavity semiconductor laser has been demonstrated by using multisegment composite-cavity configuration and automatic frequency control loop with feedback to control the external cavity length. The time period of mode-hopping free SLM operation has been observed to be more than 24 hours with a frequency shift of about 28 MHz and a linewidth of less than 200 kHz.

  5. CW, single-frequency 229nm laser source for Cd-cooling by harmonic conversion

    NASA Astrophysics Data System (ADS)

    Kaneda, Yushi; Yarborough, J. M.; Merzlyak, Yevgeny

    2015-02-01

    More than 200mW of CW 229nm for Cd atom cooling application was generated by the 4th harmonic of a single frequency optically pumped semiconductor laser using a 10-mm long, Brewster-cut BBO crystal in an external cavity. With 650mW of 458nm input, 216mW of 229nm power was observed. Conversion efficiency from 458nm to 229nm was more than 33%.

  6. Dual-color three-dimensional STED microscopy with a single high-repetition-rate laser

    PubMed Central

    Han, Kyu Young; Ha, Taekjip

    2016-01-01

    We describe a dual-color three-dimensional stimulated emission depletion (3D-STED) microscopy employing a single laser source with a repetition rate of 80 MHz. Multiple excitation pulses synchronized with a STED pulse were generated by a photonic crystal fiber and the desired wavelengths were selected by an acousto-optic tunable filter with high spectral purity. Selective excitation at different wavelengths permits simultaneous imaging of two fluorescent markers at a nanoscale resolution in three dimensions. PMID:26030581

  7. Single-pulse, laser-saturated fluorescence measurements of OH in turbulent nonpremixed flames

    NASA Technical Reports Server (NTRS)

    Lucht, R. P.; Sweeney, D. W.; Laurendeau, N. M.; Drake, M. C.; Lapp, M.; Pitz, R. W.

    1984-01-01

    A single-pulse, laser-saturated fluorescence technique has been developed for absolute OH concentration measurements with a temporal resolution of 2 nsec, a spatial resolution of less than 0.1 cu mm, and an estimated accuracy of + or - 30 percent. It has been applied in laminar, transitional, and turbulent hydrogen-air diffusion flames, providing the first reported quantitative measurements of average values, rms fluctuations, and probability-density functions of OH-radical concentration in nonpremixed flames.

  8. Reliable single-mode diode lasers at 200 mW

    NASA Astrophysics Data System (ADS)

    Li, Benjamin; Craig, Richard R.; Gignac, William J.; Huang, Zhe; Zucker, Erik P.

    1994-06-01

    Long duration life tests of approximately 6,000 hours on AlGaAs single-mode lasers operating at 200 mW and 50 degree(s)C indicate that high reliability can be obtained under these conditions. The projected median life is 140,000 hr and MTBF is 100,000 hr. These results compare favorably with data from other material systems.

  9. Laser Microsurgery Permits Fungal Plasma Membrane Single-Ion-Channel Resolution at the Hyphal Tip

    PubMed Central

    Véry, Anne-Aliénor; Davies, Julia M.

    1998-01-01

    A method for formation of high-electrical-resistance seals on the Neurospora crassa plasma membrane, allowing resolution of single-ion-channel activity by patch clamp electrophysiology, is reported. Laser microsurgery permits access to the hyphal apex without enzymatic cell wall digestion and loss of morphological polarity. Cell wall reformation is delayed by brefeldin. This method can allow full characterization of apical plasma membrane channels, which are implicated in tip growth. PMID:16349556

  10. Single-pulse resonant magnetic scattering using a soft x-ray free-electron laser

    SciTech Connect

    Gutt, C.; Streit-Nierobisch, S.; Stadler, L.-M.; Faeustlin, R. R.; Treusch, R.; Feldhaus, J.; Weckert, E.; Vartanyants, I. A.; Gruebel, G.; Pfau, B.; Guenther, C. M.; Koennecke, R.; Eisebitt, S.; Froemter, R.; Kobs, A.; Stickler, D.; Oepen, H. P.; Grunze, M.; Rosenhahn, A.; Wilhein, T.

    2010-03-01

    We report on single-pulse resonant magnetic scattering experiments using soft x-ray pulses generated by the free-electron laser FLASH at DESY. We could record a magnetic diffraction pattern from a Co/Pt multilayer sample at the Co M{sub 2,3} edge with a single 30-fs-long FEL pulse. The analysis of the magnetic small-angle scattering signal for subsequent pulses indicates a threshold energy density below which there is no indication that the magnetic properties of the sample might be altered.

  11. Optical trapping and rotation of airborne absorbing particles with a single focused laser beam

    NASA Astrophysics Data System (ADS)

    Lin, Jinda; Li, Yong-qing

    2014-03-01

    We measure the periodic circular motion of single absorbing aerosol particles that are optically trapped with a single focused Gaussian beam and rotate around the laser propagation direction. The scattered light from the trapped particle is observed to be directional and change periodically at 0.4-20 kHz. The instantaneous positions of the moving particle within a rotation period are measured by a high-speed imaging technique using a charge coupled device camera and a repetitively pulsed light-emitting diode illumination. The centripetal acceleration of the trapped particle as high as ˜20 times the gravitational acceleration is observed and is attributed to the photophoretic forces.

  12. Alternating Laser Excitation for Solution-Based Single-Molecule FRET.

    PubMed

    Kapanidis, Achillefs; Majumdar, Devdoot; Heilemann, Mike; Nir, Eyal; Weiss, Shimon

    2015-11-01

    Single-molecule fluorescence resonance energy transfer (smFRET) has been widely applied to the study of fluorescently labeled biomolecules on surfaces and in solution. Sorting single molecules based on fluorescent dye stoichiometry provides one with further layers of information and also enables "filtering" of unwanted molecules from the analysis. We accomplish this sorting by using alternating laser excitation (ALEX) in combination with smFRET measurements; here we describe the implementation of these methodologies for the study of biomolecules in solution. PMID:26527772

  13. Catastrophic optical mirror damage in diode lasers monitored during single-pulse operation

    NASA Astrophysics Data System (ADS)

    Ziegler, Mathias; Tomm, Jens W.; Reeber, David; Elsaesser, Thomas; Zeimer, Ute; Larsen, Henning E.; Petersen, Paul M.; Andersen, Peter E.

    2009-05-01

    Catastrophic optical mirror damage (COMD) is analyzed for 808 nm emitting diode lasers in single-pulse operation in order to separate facet degradation from subsequent degradation processes. During each pulse, nearfield and thermal images are monitored. A temporal resolution better than 7 μs is achieved. The thermal runaway process is unambiguously related to the occurrence of a "thermal flash." A one-by-one correlation between nearfield, thermal flash, thermal runaway, and structural damage is observed. The single-pulse excitation technique allows for controlling the propagation of the structural damage into the cavity. We propose this technique for the analysis of early stages of COMD.

  14. Optical trapping and rotation of airborne absorbing particles with a single focused laser beam

    SciTech Connect

    Lin, Jinda; Li, Yong-qing

    2014-03-10

    We measure the periodic circular motion of single absorbing aerosol particles that are optically trapped with a single focused Gaussian beam and rotate around the laser propagation direction. The scattered light from the trapped particle is observed to be directional and change periodically at 0.4–20 kHz. The instantaneous positions of the moving particle within a rotation period are measured by a high-speed imaging technique using a charge coupled device camera and a repetitively pulsed light-emitting diode illumination. The centripetal acceleration of the trapped particle as high as ∼20 times the gravitational acceleration is observed and is attributed to the photophoretic forces.

  15. Wiring up pre-characterized single-photon emitters by laser lithography

    PubMed Central

    Shi, Q.; Sontheimer, B.; Nikolay, N.; Schell, A. W.; Fischer, J.; Naber, A.; Benson, O.; Wegener, M.

    2016-01-01

    Future quantum optical chips will likely be hybrid in nature and include many single-photon emitters, waveguides, filters, as well as single-photon detectors. Here, we introduce a scalable optical localization-selection-lithography procedure for wiring up a large number of single-photon emitters via polymeric photonic wire bonds in three dimensions. First, we localize and characterize nitrogen vacancies in nanodiamonds inside a solid photoresist exhibiting low background fluorescence. Next, without intermediate steps and using the same optical instrument, we perform aligned three-dimensional laser lithography. As a proof of concept, we design, fabricate, and characterize three-dimensional functional waveguide elements on an optical chip. Each element consists of one single-photon emitter centered in a crossed-arc waveguide configuration, allowing for integrated optical excitation and efficient background suppression at the same time. PMID:27507165

  16. Wiring up pre-characterized single-photon emitters by laser lithography

    NASA Astrophysics Data System (ADS)

    Shi, Q.; Sontheimer, B.; Nikolay, N.; Schell, A. W.; Fischer, J.; Naber, A.; Benson, O.; Wegener, M.

    2016-08-01

    Future quantum optical chips will likely be hybrid in nature and include many single-photon emitters, waveguides, filters, as well as single-photon detectors. Here, we introduce a scalable optical localization-selection-lithography procedure for wiring up a large number of single-photon emitters via polymeric photonic wire bonds in three dimensions. First, we localize and characterize nitrogen vacancies in nanodiamonds inside a solid photoresist exhibiting low background fluorescence. Next, without intermediate steps and using the same optical instrument, we perform aligned three-dimensional laser lithography. As a proof of concept, we design, fabricate, and characterize three-dimensional functional waveguide elements on an optical chip. Each element consists of one single-photon emitter centered in a crossed-arc waveguide configuration, allowing for integrated optical excitation and efficient background suppression at the same time.

  17. Wiring up pre-characterized single-photon emitters by laser lithography.

    PubMed

    Shi, Q; Sontheimer, B; Nikolay, N; Schell, A W; Fischer, J; Naber, A; Benson, O; Wegener, M

    2016-01-01

    Future quantum optical chips will likely be hybrid in nature and include many single-photon emitters, waveguides, filters, as well as single-photon detectors. Here, we introduce a scalable optical localization-selection-lithography procedure for wiring up a large number of single-photon emitters via polymeric photonic wire bonds in three dimensions. First, we localize and characterize nitrogen vacancies in nanodiamonds inside a solid photoresist exhibiting low background fluorescence. Next, without intermediate steps and using the same optical instrument, we perform aligned three-dimensional laser lithography. As a proof of concept, we design, fabricate, and characterize three-dimensional functional waveguide elements on an optical chip. Each element consists of one single-photon emitter centered in a crossed-arc waveguide configuration, allowing for integrated optical excitation and efficient background suppression at the same time. PMID:27507165

  18. All-solid-state deep ultraviolet laser for single-photon ionization mass spectrometry.

    PubMed

    Yuan, Chengqian; Liu, Xianhu; Zeng, Chenghui; Zhang, Hanyu; Jia, Meiye; Wu, Yishi; Luo, Zhixun; Fu, Hongbing; Yao, Jiannian

    2016-02-01

    We report here the development of a reflectron time-of-flight mass spectrometer utilizing single-photon ionization based on an all-solid-state deep ultraviolet (DUV) laser system. The DUV laser was achieved from the second harmonic generation using a novel nonlinear optical crystal KBe2BO3F2 under the condition of high-purity N2 purging. The unique property of this laser system (177.3-nm wavelength, 15.5-ps pulse duration, and small pulse energy at ∼15 μJ) bears a transient low power density but a high single-photon energy up to 7 eV, allowing for ionization of chemicals, especially organic compounds free of fragmentation. Taking this advantage, we have designed both pulsed nanospray and thermal evaporation sources to form supersonic expansion molecular beams for DUV single-photon ionization mass spectrometry (DUV-SPI-MS). Several aromatic amine compounds have been tested revealing the fragmentation-free performance of the DUV-SPI-MS instrument, enabling applications to identify chemicals from an unknown mixture. PMID:26931868

  19. Broad-stripe single longitudinal mode laser based on metal slots

    NASA Astrophysics Data System (ADS)

    Jia, Peng; Qin, Li; Chen, Yongyi; Zhang, Jianwei; Zhang, Jian; Zhang, Xing; Zeng, Yugang; Shan, Xiaonan; Ning, Yongqiang; Wang, Lijun

    2016-04-01

    Single-longitudinal-mode end-emitting laser with 10 periods of metal slots at around 956 nm has been fabricated. 100 μm wide broad-stripe and ten periods of 9.5 μm periodicity metal slots are defined by i-line lithography and dry etching. Experimentally, continuous-wave power of 213 mW has achieved, at a slope efficiency of 520 mW/A, having a 3 dB spectrum width of less than 0.04 nm at 900 mA, and operating in a stable single longitudinal mode with the side-mode suppression ratio (SMSR) of 42 dB. We prove that metal slots introduce sufficient loss into the cavity to filter out the wanted mode, and is more efficient on our chip structure than traditional slot laser. This paper provides a new method for the realizing high power broad-stripe (~100 μm) laser and array with single longitudinal mode operation.

  20. All-solid-state deep ultraviolet laser for single-photon ionization mass spectrometry

    NASA Astrophysics Data System (ADS)

    Yuan, Chengqian; Liu, Xianhu; Zeng, Chenghui; Zhang, Hanyu; Jia, Meiye; Wu, Yishi; Luo, Zhixun; Fu, Hongbing; Yao, Jiannian

    2016-02-01

    We report here the development of a reflectron time-of-flight mass spectrometer utilizing single-photon ionization based on an all-solid-state deep ultraviolet (DUV) laser system. The DUV laser was achieved from the second harmonic generation using a novel nonlinear optical crystal KBe2BO3F2 under the condition of high-purity N2 purging. The unique property of this laser system (177.3-nm wavelength, 15.5-ps pulse duration, and small pulse energy at ˜15 μJ) bears a transient low power density but a high single-photon energy up to 7 eV, allowing for ionization of chemicals, especially organic compounds free of fragmentation. Taking this advantage, we have designed both pulsed nanospray and thermal evaporation sources to form supersonic expansion molecular beams for DUV single-photon ionization mass spectrometry (DUV-SPI-MS). Several aromatic amine compounds have been tested revealing the fragmentation-free performance of the DUV-SPI-MS instrument, enabling applications to identify chemicals from an unknown mixture.

  1. Laser direct writing of complex radially varying single-mode polymer waveguide structures

    NASA Astrophysics Data System (ADS)

    Kruse, Kevin; Peng, Jie; Middlebrook, Christopher T.

    2015-07-01

    Increasing board-to-board and chip-to-chip computational data rates beyond 12.5 Gbs will require the use of single-mode polymer waveguides (WGs) that have high bandwidths and are able to be wavelength division multiplexed. Laser direct writing (LDW) of polymer WGs provides a scalable and reconfigurable maskless procedure compared to common photolithography fabrication. LDW of straights and radial curves are readily achieved using predefined drive commands of the two-axis direct drive linear stage system. Using the laser direct write process for advanced WG structures requires stage-drive programming techniques that account for specified polymer material exposure durations. Creating advanced structures such as WG S-bends into single-mode polymer WG builds provides designers with the ability to affect pitch control, optical coupling, and reduce footprint requirements. Fabrication of single-mode polymer WG segmented radial arcs is achieved through a smooth radial arc user-programmed defined mathematical algorithm. Cosine and raised-sine S-bends are realized through a segmentation method where the optimal incremental step length and bend dimensions are controlled to achieve minimal structure loss. Laser direct written S-bends are compared with previously published photolithographic S-bend results using theoretical bend loss models. Fabrication results show that LDW is a viable method in the fabrication of advanced polymer WG structures.

  2. Femtosecond laser fabricated microfluorescence-activated cell sorter for single cell recovery

    NASA Astrophysics Data System (ADS)

    Bragheri, F.; Paiè, P.; Nava, G.; Yang, T.; Minzioni, P.; Martinez Vazquez, R.; Bellini, N.; Ramponi, R.; Cristiani, I.; Osellame, R.

    2014-03-01

    Manipulation, sorting and recovering of specific live cells from samples containing less than a few thousand cells is becoming a major hurdle in rare cell exploration such as stem cell research or cell based diagnostics. Moreover the possibility of recovering single specific cells for culturing and further analysis would be of great impact in many biological fields ranging from regenerative medicine to cancer therapy. In recent years considerable effort has been devoted to the development of integrated and low-cost optofluidic devices able to handle single cells, which usually rely on microfluidic circuits that guarantee a controlled flow of the cells. Among the different microfabrication technologies, femtosecond laser micromachining (FLM) is ideally suited for this purpose as it provides the integration of both microfluidic and optical functions on the same glass chip leading to monolithic, robust and portable devices. Here a new optofluidic device is presented, which is capable of sorting and recovering of single cells, through optical forces, on the basis of their fluorescence and. Both fluorescence detection and single cell sorting functions are integrated in the microfluidic chip by FLM. The device, which is specifically designed to operate with a limited amount of cells but with a very high selectivity, is fabricated by a two-step process that includes femtosecond laser irradiation followed by chemical etching. The capability of the device to act as a micro fluorescence-activated cell sorter has been tested on polystyrene beads and on tumor cells and the results on the single live cell recovery are reported.

  3. Single shot ultrafast dynamic ellipsometry (UDE) of laser-driven shocks in single crystal explosives

    SciTech Connect

    Whitley, Von H; Mcgrane, Shawn D; Moore, David S; Eakins, Dan E; Bolme, Cindy A

    2009-01-01

    We report on the first experiments to measure states in shocked energetic single crystals with dynamic ellipsometry. We demonstrate that these ellipsometric techniques can produce reasonable Hugoniot values using small amounts of crystalline RDX and PETN. Pressures, particle velocities and shock velocities obtained using shocked ellipsometry are comparable to those found using gas-gun flyer plates and molecular dynamics calculations. The adaptation of the technique from uniform thin films of polymers to thick non-perfect crystalline materials was a significant achievement. Correct sample preparation proved to be a crucial component. Through trial and error, we were able to resolve polishing issues, sample quality problems, birefringence effects and mounting difficulties that were not encountered using thin polymer films.

  4. Singly resonant sum-frequency generation of 520-nm laser via a variable input-coupling transmission cavity

    NASA Astrophysics Data System (ADS)

    Guo, Shanlong; Ge, Yulong; He, Jun; Wang, Junmin

    2015-11-01

    We experimentally present a three-mirror folded singly resonant sum-frequency generation (SFG) cavity with an adjustable input coupling, which has been applied to 520-nm single-frequency laser generation via 780-nm laser and 1560-nm laser frequency mixing in a periodically poled KTiOPO4 crystal (PPKTP). A continuous variation in the input coupling reflectivity from 81.4 to 96.1% for 780-nm resonant laser is achieved by tilting the input coupler, and the impedance matching of the resonator can be optimized. Up to 268 mW of SFG output power at 520-nm is obtained with 6.8 W of the 1560-nm laser input and 1.5 W of 780-nm laser input.

  5. Stable CW Single-Frequency Operation of Fabry-Perot Laser Diodes by Self-Injection Phase Locking

    NASA Technical Reports Server (NTRS)

    Duerksen, Gary L.; Krainak, Michael A.

    1999-01-01

    Previously, single-frequency semiconductor laser operation using fiber Bragg gratings has been achieved by two methods: 1) use of the FBG as the output coupler for an anti-reflection-coated semiconductor gain element'; 2) pulsed operation of a gain-switched Fabry-Perot laser diode with FBG-optical and RF-electrical feedback. Here, we demonstrate CW single frequency operation from a non-AR coated Fabry-Perot laser diode using only FBG optical feedback. We coupled a nominal 935 run-wavelength Fabry-Perot laser diode to an ultra narrow band (18 pm) FBG. When tuned by varying its temperature, the laser wavelength is pulled toward the centerline of the Bragg grating, and the spectrum of the laser output is seen to fall into three discrete stability regimes as measured by the side-mode suppression ratio.

  6. Dynamic imaging of a single gold nanoparticle in liquid irradiated by off-resonance femtosecond laser

    NASA Astrophysics Data System (ADS)

    Boutopoulos, Christos; Hatef, Ali; Fortin-Deschênes, Matthieu; Meunier, Michel

    2015-07-01

    Plasmonic nanoparticles can lead to extreme confinement of the light in the near field. This unique ability of plasmonic nanoparticles can be used to generate nanobubbles in liquid. In this work, we demonstrate with single-particle monitoring that 100 nm gold nanoparticles (AuNPs) irradiated by off-resonance femtosecond (fs) laser in the tissue therapeutic optical window (λ = 800 nm), can act as a durable nanolenses in liquid and provoke nanocavitation while remaining intact. We have employed combined ultrafast shadowgraphic imaging, in situ dark field imaging and dynamic tracking of AuNP Brownian motion to ensure the study of individual AuNPs/nanolenses under multiple fs laser pulses. We demonstrate that 100 nm AuNPs can generate multiple, highly confined (radius down to 550 nm) and transient (life time < 50 ns) nanobubbles. The latter is of significant importance for future development of in vivo AuNP-assisted laser nanosurgery and theranostic applications, where AuNP fragmentation should be avoided to prevent side effects, such as cytotoxicity and immune system's response. The experimental results have been correlated with theoretical modeling to provide an insight to the AuNP-safe cavitation mechanism as well as to investigate the deformation mechanism of the AuNPs at high laser fluences.Plasmonic nanoparticles can lead to extreme confinement of the light in the near field. This unique ability of plasmonic nanoparticles can be used to generate nanobubbles in liquid. In this work, we demonstrate with single-particle monitoring that 100 nm gold nanoparticles (AuNPs) irradiated by off-resonance femtosecond (fs) laser in the tissue therapeutic optical window (λ = 800 nm), can act as a durable nanolenses in liquid and provoke nanocavitation while remaining intact. We have employed combined ultrafast shadowgraphic imaging, in situ dark field imaging and dynamic tracking of AuNP Brownian motion to ensure the study of individual AuNPs/nanolenses under multiple fs

  7. Lasers.

    ERIC Educational Resources Information Center

    Schewe, Phillip F.

    1981-01-01

    Examines the nature of laser light. Topics include: (1) production and characteristics of laser light; (2) nine types of lasers; (3) five laser techniques including holography; (4) laser spectroscopy; and (5) laser fusion and other applications. (SK)

  8. Catastrophic optical degradation of the output facet of high-power single-transverse-mode diode lasers. 1. Physical model

    SciTech Connect

    Miftakhutdinov, D R; Bogatov, Alexandr P; Drakin, A E

    2010-09-10

    The physical model of catastrophic optical degradation (COD) of the output facet of high-power single- transverse-mode diode lasers is developed. The model excels other models both in completeness of the physical analysis of the processes leading to COD and in allowance for design feature of lasers used to increase the COD threshold - protective coating of the output facet and current limitations near it. (lasers)

  9. Frequency Swept Diode-pumped Single Frequency TM,Ho:YLiF Laser for spaceborne Doppler Lidar

    NASA Technical Reports Server (NTRS)

    McGuckin, B. T.; Menzies, R. T.; Esproles, C.

    1993-01-01

    Optical heterodyne experiments involving the photomixing of two single frequency, deode-pumped thulium holmium yttrium lithium flouride lasers are described. Operated in external frquency stabilization loops, the lasers exhibit 1MHz short term stability, and are photomixed and offset-locked at 140 MHz. Summation of sine wave modulation onto the PZT control voltage on one laser results in frequency swept operation over a continuous tuning range of 160 MHz.

  10. Final report on LDRD project : advanced optical trigger systems.

    SciTech Connect

    Roose, Lars D.; Hadley, G. Ronald; Mar, Alan; Serkland, Darwin Keith; Geib, Kent Martin; Sullivan, Charles Thomas; Keeler, Gordon Arthur; Bauer, Thomas M.; Peake, Gregory Merwin; Loubriel, Guillermo Manuel; Montano, Victoria A.

    2008-09-01

    are difficult to scale and manufacture with the required uniformity. As a promising alternative to multiple discrete edge-emitting lasers, a single wafer of vertical-cavity surface-emitting lasers (VCSELs) can be lithographically patterned to achieve the desired layout of parallel line-shaped emitters, in which adjacent lasers utilize identical semiconductor material and thereby achieve a degree of intrinsic optical uniformity. Under this LDRD project, we have fabricated arrays of uncoupled circular-aperture VCSELs to approximate a line-shaped illumination pattern, achieving optical fill factors ranging from 2% to 30%. We have applied these VCSEL arrays to demonstrate single and dual parallel line-filament triggering of PCSS devices. Moreover, we have developed a better understanding of the illumination requirements for stable triggering of multiple-filament PCSS devices using VCSEL arrays. We have found that reliable triggering of multiple filaments requires matching of the turn-on time of adjacent VCSEL line-shaped-arrays to within approximately 1 ns. Additionally, we discovered that reliable triggering of PCSS devices at low voltages requires more optical power than we obtained with our first generation of VCSEL arrays. A second generation of higher-power VCSEL arrays was designed and fabricated at the end of this LDRD project, and testing with PCSS devices is currently underway (as of September 2008).

  11. Indirect measurement of machine tool motion axis error with single laser tracker

    NASA Astrophysics Data System (ADS)

    Wu, Zhaoyong; Li, Liangliang; Du, Zhengchun

    2015-02-01

    For high-precision machining, a convenient and accurate detection of motion error for machine tools is significant. Among common detection methods such as the ball-bar method, the laser tracker approach has received much more attention. As a high-accuracy measurement device, laser tracker is capable of long-distance and dynamic measurement, which increases much flexibility during the measurement process. However, existing methods are not so satisfactory in measurement cost, operability or applicability. Currently, a plausible method is called the single-station and time-sharing method, but it needs a large working area all around the machine tool, thus leaving itself not suitable for the machine tools surrounded by a protective cover. In this paper, a novel and convenient positioning error measurement approach by utilizing a single laser tracker is proposed, followed by two corresponding mathematical models including a laser-tracker base-point-coordinate model and a target-mirror-coordinates model. Also, an auxiliary apparatus for target mirrors to be placed on is designed, for which sensitivity analysis and Monte-Carlo simulation are conducted to optimize the dimension. Based on the method proposed, a real experiment using single API TRACKER 3 assisted by the auxiliary apparatus is carried out and a verification experiment using a traditional RENISHAW XL-80 interferometer is conducted under the same condition for comparison. Both results demonstrate a great increase in the Y-axis positioning error of machine tool. Theoretical and experimental studies together verify the feasibility of this method which has a more convenient operation and wider application in various kinds of machine tools.

  12. Colliding pulse mode-locked lasers as light sources for single-shot holography

    NASA Astrophysics Data System (ADS)

    Grosse, Doris; Koukourakis, Nektarios; Gerhardt, Nils C.; Schlauch, Tobias; Balzer, Jan C.; Klehr, Andreas; Erbert, Götz; Tränkle, Günther; Hofmann, Martin R.

    2011-05-01

    So far, concepts for three dimensional biomedical imaging rely on scanning in at least one dimension. Single-shot holography1, in contrast, stores three-dimensional information encoded in an electro-magnetic wave scattered back from a sample in one single hologram. Single-shot holography operates with simultaneous recordings of holograms at different wavelengths. While the lateral sample information is stored in the interference patterns of individual holograms, the depth information is obtained from the spectral distribution at each lateral image point, similar to Fourier-domain optical coherence tomography2. Consequently, the depth resolution of the reconstructed image is determined by the bandwidth of the light source, so that a broadband light source is needed to obtain high depth resolution. Additionally, the holographic material, in which the holograms are stored, restricts the useable bandwidth. A thick photorefractive crystal can store several holograms of different wavelengths at once. As the crystal works best when using a source with a discrete spectrum, a light source is needed that has a spectrum with well distinguishable laser lines. In a proof-of-principle experiment, we use colliding pulse mode-locked (CPM)3 laser diodes as light sources with a comb-like spectrum to demonstrate the concept of single-shot holography by storing multiple holograms at the same time in a photorefractive Rh:BaTiO3 crystal.

  13. Low-visibility light-intensity laser-triggered release of entrapped calcein from 1,2-bis (tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine liposomes is mediated through a type I photoactivation pathway

    PubMed Central

    Yavlovich, Amichai; Viard, Mathias; Gupta, Kshitij; Sine, Jessica; Vu, Mylinh; Blumenthal, Robert; Tata, Darrell B; Puri, Anu

    2013-01-01

    We recently reported on the physical characteristics of photo-triggerable liposomes containing dipalmitoylphosphatidylcholine (DPPC), and 1,2-bis (tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine (DC8,9PC) carrying a photo agent as their payload. When exposed to a low-intensity 514 nm wavelength (continuous-wave) laser light, these liposomes were observed to release entrapped calcein green (Cal-G; Ex/Em 490/517 nm) but not calcein blue (Cal-B; Ex/Em 360/460 nm). In this study, we have investigated the mechanism for the 514 nm laser-triggered release of the Cal-G payload using several scavengers that are known specifically to inhibit either type I or type II photoreaction pathways. Liposomes containing DPPC:DC8,9PC: distearoylphosphatidylethanolamine (DSPE)-polyethylene glycol (PEG)-2000 (86:10:04 mole ratio) were loaded either with fluorescent (calcein) or nonfluorescent (3H-inulin) aqueous markers. In addition, a non-photo-triggerable formulation (1-palmitoyl-2-oleoyl phosphatidylcholine [POPC]:DC8,9PC:DSPE-PEG2000) was also studied with the same payloads. The 514 nm wavelength laser exposure on photo-triggerable liposomes resulted in the release of Cal-G but not that of Cal-B or 3H-inulin, suggesting an involvement of a photoactivated state of Cal-G due to the 514 nm laser exposure. Upon 514 nm laser exposures, substantial hydrogen peroxide (H2O2, ≈100 μM) levels were detected from only the Cal-G loaded photo-triggerable liposomes but not from Cal-B-loaded liposomes (≤10 μM H2O2). The Cal-G release from photo-triggerable liposomes was found to be significantly inhibited by ascorbic acid (AA), resulting in a 70%–80% reduction in Cal-G release. The extent of AA-mediated inhibition of Cal-G release from the liposomes also correlated with the consumption of AA. No AA consumption was detected in the 514 nm laserexposed Cal B-loaded liposomes, thus confirming a role of photoactivation of Cal-G in liposome destabilization. Inclusion of 100 mM K3Fe(CN)6 (a

  14. 2D photoacoustic scanning imaging with a single pulsed laser diode excitation

    NASA Astrophysics Data System (ADS)

    Chen, Xuegang; Li, Changwei; Zeng, Lvming; Liu, Guodong; Huang, Zhen; Ren, Zhong

    2011-11-01

    A portable near-infrared photoacoustic scanning imaging system has been developed with a single pulsed laser diode, which was integrated with an optical lens system to straightforward boost the laser energy density for photoacoustic generation. The 905 nm laser diode provides a maximum energy output of 14 μJ within 100 ns pulse duration, and the pulse repetition frequency rate is 0.8 KHz. As a possible alternative light source, the preliminary 2D photoacoustic results primely correspond with the test phantoms of umbonate extravasated gore and knotted blood vessel network. The photoacoustic SNR can reach 20.6+/-1.2 dB while signal averaging reduces to 128 pulses from thousands to tens of thousands times, and the signal acquisition time accelerates to less than 0.2 s in each A-scan, especially the volume of the total radiation source is only 10 × 3 × 3 cm3. It demonstrated that the pulsed semiconductor laser could be a candidate of photoacoustic equipment for daily clinical application.

  15. 2D photoacoustic scanning imaging with a single pulsed laser diode excitation

    NASA Astrophysics Data System (ADS)

    Chen, Xuegang; Li, Changwei; Zeng, Lvming; Liu, Guodong; Huang, Zhen; Ren, Zhong

    2012-03-01

    A portable near-infrared photoacoustic scanning imaging system has been developed with a single pulsed laser diode, which was integrated with an optical lens system to straightforward boost the laser energy density for photoacoustic generation. The 905 nm laser diode provides a maximum energy output of 14 μJ within 100 ns pulse duration, and the pulse repetition frequency rate is 0.8 KHz. As a possible alternative light source, the preliminary 2D photoacoustic results primely correspond with the test phantoms of umbonate extravasated gore and knotted blood vessel network. The photoacoustic SNR can reach 20.6+/-1.2 dB while signal averaging reduces to 128 pulses from thousands to tens of thousands times, and the signal acquisition time accelerates to less than 0.2 s in each A-scan, especially the volume of the total radiation source is only 10 × 3 × 3 cm3. It demonstrated that the pulsed semiconductor laser could be a candidate of photoacoustic equipment for daily clinical application.

  16. Purity of the single frequency mode of a hybrid semiconductor-fiber laser.

    PubMed

    Wahbeh, Mamoun; Kashyap, Raman

    2015-06-15

    The penalty of extending the cavity length of a laser diode when seeking a linewidth reduction is normally revealed by poor side mode suppression, which prevents the laser from operating purely in a single mode of the external cavity. A hybrid laser, based on a C-band semiconductor optical amplifier combined with a long erbium doped fiber external cavity, is carefully engineered to operate with high spectral purity and outstanding stability. For the first time, a side-mode suppression ratio of ≥42 dB, measured at a resolution of 1.16 pm (149 MHz) at all intra-cavity powers above the lasing threshold, is reported. The output power at the peak lasing wavelength is 13.3 dBm. Also, the ability to lock such a hybrid laser to a particular external-cavity mode is realized for the first time. Excluding the effect of mechanical and thermal drifts on the cavity length, the long-term frequency stability is demonstrated to be within ± 11 Hz while the long-term linewidth is 2.26 kHz, measured using the self-beating technique under free running conditions. PMID:26193582

  17. Dynamic imaging of a single gold nanoparticle in liquid irradiated by off-resonance femtosecond laser.

    PubMed

    Boutopoulos, Christos; Hatef, Ali; Fortin-Deschênes, Matthieu; Meunier, Michel

    2015-07-21

    Plasmonic nanoparticles can lead to extreme confinement of the light in the near field. This unique ability of plasmonic nanoparticles can be used to generate nanobubbles in liquid. In this work, we demonstrate with single-particle monitoring that 100 nm gold nanoparticles (AuNPs) irradiated by off-resonance femtosecond (fs) laser in the tissue therapeutic optical window (λ = 800 nm), can act as a durable nanolenses in liquid and provoke nanocavitation while remaining intact. We have employed combined ultrafast shadowgraphic imaging, in situ dark field imaging and dynamic tracking of AuNP Brownian motion to ensure the study of individual AuNPs/nanolenses under multiple fs laser pulses. We demonstrate that 100 nm AuNPs can generate multiple, highly confined (radius down to 550 nm) and transient (life time < 50 ns) nanobubbles. The latter is of significant importance for future development of in vivo AuNP-assisted laser nanosurgery and theranostic applications, where AuNP fragmentation should be avoided to prevent side effects, such as cytotoxicity and immune system's response. The experimental results have been correlated with theoretical modeling to provide an insight to the AuNP-safe cavitation mechanism as well as to investigate the deformation mechanism of the AuNPs at high laser fluences. PMID:26104482

  18. Analysis of laser-generated plasma ionizing radiation by synthetic single crystal diamond detectors

    NASA Astrophysics Data System (ADS)

    Marinelli, M.; Milani, E.; Prestopino, G.; Verona, C.; Verona-Rinati, G.; Cutroneo, M.; Torrisi, L.; Margarone, D.; Velyhan, A.; Krasa, J.; Krousky, E.

    2013-05-01

    Diamond based detectors have been used in order to analyze the ionizing radiation emitted from the laser-generated plasma. High energy proton/ion beams were generated at Prague Asterix Laser System (PALS) Centre by the sub-nanosecond kJ-class laser at intensities above 1016 W/cm2. The tested detectors consisted of a photoconductive device based on high quality chemical vapor deposition (CVD) single crystal diamond, produced at Rome "Tor Vergata" University. They have been operated in planar configuration, having inter-digitized electrodes. The proposed diamond detectors were able to measure UV, X-rays, electrons and ions. They have been employed in time-of-flight (TOF) configuration and their reliability was checked by comparison with standard ion collectors (mostly used at PALS). Both the forward and backward expanding plasma was characterized in the experiment. The results indicate that diamond detectors are very promising for the characterization of fast proton and ion beams produced by high power laser systems.

  19. Integrated guided wave generation and sensing using a single laser source and optical fibers

    NASA Astrophysics Data System (ADS)

    Lee, Hyeonseok; Park, Hyun-Jun; Sohn, Hoon; Kwon, Il-Bum

    2010-10-01

    This study proposes an integrated lead zirconate titanate/fiber Bragg grating (PZT/FBG) system that can generate and measure guided waves for structural health monitoring (SHM) using a common laser source and optical cables. Among various SHM devices used for guided wave generation and sensing, PZT transducers and FBG sensors have been widely used because of their light weight, non-intrusive nature and compactness. To take the best advantage of the merits of these SHM devices, a combination of PZT-based guided wave generation and FBG-based sensing has been attempted by some researchers. However, the existing hybrid approaches have two independent systems: a wave generation system using electrical devices and a sensing system with optical devices. We have developed a fully integrated PZT/FBG system that uses a single laser source and optical cables. This system can alleviate problems associated with conventional electrical cables, such as electromagnetic interference, signal attenuation and vulnerability to noise. A tunable laser, the common power source for guided wave generation and sensing, is modulated and amplified to excite PZT. This laser is also used with FBG sensors for measuring high-speed strain changes induced by guided waves. The feasibility of this system has been experimentally demonstrated using an aluminum plate.

  20. Guided wave generation and sensing system using a single laser source and optical fibers

    NASA Astrophysics Data System (ADS)

    Lee, Hyeonseok; Park, Hyun-Jun; Sohn, Hoon; Kwon, Il-bum

    2010-04-01

    Structural health monitoring (SHM) techniques based on guided waves have been of great interests to many researchers. Among various SHM devices used for guided wave generation and sensing, lead zirconate titanate (PZT) transducers and fiber Bragg grating (FBG) sensors have been widely used because of their light weight, non-intrusive nature and compactness. To best take advantage of their merits, combination of PZT-based guided wave excitation and FBG-based sensing has been attempted by a few researchers. However, the PZT-based actuation and the FBG-based sensing are basically two independent systems in the past studies. This study proposes an integrated PZT/FBG system using a single laser source. Since power and data delivery is based on optical fibers, it may alleviate problems associated with conventional wire cables such as electromagnetic interference (EMI) and power/data attenuation. The experimental procedure for the proposed system is as follows. First, a tunable laser is used as the common power source for guided wave generation and sensing. The tunable laser beam is modulated and amplified to contain an arbitrary waveform. Then, it is transmitted to the PZT transducer node through an optical fiber for guided wave actuation. The transmitted laser beam is also used with the FBG sensor to measure high-speed strain changes induced by guided waves. Feasibility of the proposed technique has been experimentally demonstrated using aluminum plates. The results show that the proposed system could properly generate and sense the guided waves compared to the conventional methods.