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Sample records for optically-pumped external-cavity surface-emitting

  1. 1300 nm optically pumped quantum dot spin vertical external-cavity surface-emitting laser

    NASA Astrophysics Data System (ADS)

    Alharthi, S. S.; Orchard, J.; Clarke, E.; Henning, I. D.; Adams, M. J.

    2015-10-01

    We report a room temperature optically pumped Quantum Dot-based Spin-Vertical-External-Cavity Surface-Emitting laser (QD Spin-VECSEL) operating at the telecom wavelength of 1.3 μm. The active medium was composed of 5 × 3 QD layers; each threefold group was positioned at an antinode of the standing wave of the optical field. Circularly polarized lasing in the QD-VECSEL under Continuous-Wave optical pumping has been realized with a threshold pump power of 11 mW. We further demonstrate at room temperature control of the QD-VECSEL output polarization ellipticity via the pump polarization.

  2. 1300 nm optically pumped quantum dot spin vertical external-cavity surface-emitting laser

    SciTech Connect

    Alharthi, S. S. Henning, I. D.; Adams, M. J.; Orchard, J.; Clarke, E.

    2015-10-12

    We report a room temperature optically pumped Quantum Dot-based Spin-Vertical-External-Cavity Surface-Emitting laser (QD Spin-VECSEL) operating at the telecom wavelength of 1.3 μm. The active medium was composed of 5 × 3 QD layers; each threefold group was positioned at an antinode of the standing wave of the optical field. Circularly polarized lasing in the QD-VECSEL under Continuous-Wave optical pumping has been realized with a threshold pump power of 11 mW. We further demonstrate at room temperature control of the QD-VECSEL output polarization ellipticity via the pump polarization.

  3. The optically pumped semiconductor membrane external-cavity surface-emitting laser (MECSEL): a concept based on a diamond-sandwiched active region

    NASA Astrophysics Data System (ADS)

    Kahle, Hermann; Mateo, Cherry May N.; Brauch, Uwe; Bek, Roman; Jetter, Michael; Graf, Thomas; Michler, Peter

    2017-02-01

    Semiconductor disk lasers with all their advantages1 became an important stand-alone class of solid-state lasers during the last years. However, these systems suffer from heat incorporation into the active region caused by the excess energy of the pump photons. To overcome this limitation we realized the semiconductor membrane external-cavity surface-emitting laser as a diamond heat spreader sandwiched active region design. A detailed process description towards the MECSEL2 approach is given as well as fundamental performance values. Furthermore, parasitic lateral lasing effects are discovered and investigated. Nevertheless, the MECSEL approach indicates enormous potential to revolutionize the semiconductor based disk lasers regarding available output powers at room temperature and material combinations.

  4. Intracavity Frequency Doubling of a Diode-Pumped, External Cavity, Surface Emitting Semiconductor Laser

    SciTech Connect

    Alford, W.J.; Allerman, A.A.; Crawford, M.H.; Raymond, T.D.

    1999-04-22

    The authors present a compact, robust, solid-state blue light (490 nm) source capable of greater than 5 mW of output in a TEM{sub 00} mode. This device is an optically pumped, vertical external-cavity surface-emitting laser (VECSEL) with an intracavity frequency doubling crystal.

  5. Recent Vertical External Cavity Surface Emitting Lasers (VECSELs) Developments for Sensor Applications (POSTPRINT)

    DTIC Science & Technology

    2013-02-01

    AFRL-RY-WP-TP-2013-0033 RECENT VERTICAL EXTERNAL CAVITY SURFACE EMITTING LASERS ( VECSELs ) DEVELOPMENTS FOR SENSOR APPLICATIONS (POSTPRINT...VERTICAL EXTERNAL CAVITY SURFACE EMITTING LASERS ( VECSELs ) DEVELOPMENTS FOR SENSOR APPLICATIONS (POSTPRINT) 5a. CONTRACT NUMBER In-house 5b. GRANT...Clearance Date 12 January 2012. Report contains color. 14. ABSTRACT Vertical external cavity surface emitting lasers ( VECSELs ) have proven

  6. Control of light polarization using optically spin-injected vertical external cavity surface emitting lasers

    SciTech Connect

    Frougier, J. Jaffrès, H.; Deranlot, C.; George, J.-M.; Baili, G.; Dolfi, D.; Alouini, M.; Sagnes, I.; Garnache, A.

    2013-12-16

    We fabricated and characterized an optically pumped (100)-oriented InGaAs/GaAsP multiple quantum well Vertical External Cavity Surface Emitting Laser (VECSEL). The structure is designed to allow the integration of a Metal-Tunnel-Junction ferromagnetic spin-injector for future electrical injection. We report here the control at room temperature of the electromagnetic field polarization using optical spin injection in the active medium of the VECSEL. The switching between two highly circular polarization states had been demonstrated using an M-shaped extended cavity in multi-modes lasing. This result witnesses an efficient spin-injection in the active medium of the LASER.

  7. 1-W antimonide-based vertical external cavity surface emitting laser operating at 2-microm.

    PubMed

    Härkönen, A; Guina, M; Okhotnikov, O; Rößner, K; Hümmer, M; Lehnhardt, T; Müller, M; Forchel, A; Fischer, M

    2006-07-10

    We report a high-power optically pumped semiconductor vertical external cavity surface emitting laser operating at 2-mum wavelength. The gain material consisted of 15 GaInSb quantum-wells placed within a three-lambda GaSb cavity and grown on the top of an 18-pairs AlAsSb/GaSb Bragg reflector. For thermal management we have used a transparent diamond heat spreader bonded on the top of the structure. When cooled down to 5 degrees C, the laser emitted up to 1 W of optical power in a nearly diffraction-limited Gaussian beam demonstrating the high potential of antimonide material for VECSEL fabrication.

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

    DOEpatents

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

    2002-01-01

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

  9. 5-W Yellow Laser by Intracavity Frequency Doubling of High-Power Vertical-External-Cavity Surface-Emitting Laser (POSTPRINT)

    DTIC Science & Technology

    2008-10-15

    pumped semiconductor lasers, tunable vertical-external-cavity surface-emitting laser ( VECSEL ). I. INTRODUCTION H IGH-POWER laser sources covering the...wavelengths are difficult to fabricate. Optically pumped vertical-external-cavity surface-emitting lasers ( VECSELs ) using multiquantum wells are very...highly strained InGaAs–GaAs VECSEL which can cover a significantly longer wavelength range of 1147–1197 nm. Very robust multi-Watt high-brightness

  10. Commercial mode-locked vertical external cavity surface emitting lasers

    NASA Astrophysics Data System (ADS)

    Lubeigt, Walter; Bialkowski, Bartlomiej; Lin, Jipeng; Head, C. Robin; Hempler, Nils; Maker, Gareth T.; Malcolm, Graeme P. A.

    2017-02-01

    In recent years, M Squared Lasers have successfully commercialized a range of mode-locked vertical external cavity surface emitting lasers (VECSELs) operating between 920-1050nm and producing picosecond-range pulses with average powers above 1W at pulse repetition frequencies (PRF) of 200MHz. These laser products offer a low-cost, easy-to-use and maintenance-free tool for the growing market of nonlinear microscopy. However, in order to present a credible alternative to ultrafast Ti-sapphire lasers, pulse durations below 200fs are required. In the last year, efforts have been directed to reduce the pulse duration of the Dragonfly laser system to below 200fs with a target average power above 1W at a PRF of 200MHz. This paper will describe and discuss the latest efforts undertaken to approach these targets in a laser system operating at 990nm. The relatively low PRF operation of Dragonfly lasers represents a challenging requirement for mode-locked VECSELs due to the very short upper state carrier lifetime, on the order of a few nanoseconds, which can lead to double pulsing behavior in longer cavities as the time between consecutive pulses is increased. Most notably, the design of the Dragonfly VECSEL cavity was considerably modified and the laser system extended with a nonlinear pulse stretcher and an additional compression stage. The improved Dragonfly laser system achieved pulse duration as short as 130fs with an average power of 0.85W.

  11. Femtosecond high-power quantum dot vertical external cavity surface emitting laser.

    PubMed

    Hoffmann, Martin; Sieber, Oliver D; Wittwer, Valentin J; Krestnikov, Igor L; Livshits, Daniil A; Barbarin, Yohan; Südmeyer, Thomas; Keller, Ursula

    2011-04-25

    We report on the first femtosecond vertical external cavity surface emitting laser (VECSEL) exceeding 1 W of average output power. The VECSEL is optically pumped, based on self-assembled InAs quantum dot (QD) gain layers, cooled efficiently using a thin disk geometry and passively modelocked with a fast quantum dot semiconductor saturable absorber mirror (SESAM). We developed a novel gain structure with a flat group delay dispersion (GDD) of ± 10 fs2 over a range of 30 nm around the designed operation wavelength of 960 nm. This amount of GDD is several orders of magnitude lower compared to standard designs. Furthermore, we used an optimized positioning scheme of 63 QD gain layers to broaden and flatten the spectral gain. For stable and self-starting pulse formation, we have employed a QD-SESAM with a fast absorption recovery time of around 500 fs. We have achieved 1 W of average output power with 784-fs pulse duration at a repetition rate of 5.4 GHz. The QD-SESAM and the QD-VECSEL are operated with similar cavity mode areas, which is beneficial for higher repetition rates and the integration of both elements into a modelocked integrated external-cavity surface emitting laser (MIXSEL).

  12. High-sensitivity intracavity laser absorption spectroscopy with vertical-external-cavity surface-emitting semiconductor lasers.

    PubMed

    Garnache, A; Kachanov, A A; Stoeckel, F; Planel, R

    1999-06-15

    We report the demonstration of high-sensitivity intracavity laser absorption spectroscopy with multiple-quantum-well vertical-external-cavity surface-emitting semiconductor lasers (VECSEL's). A detection limit of 3 x 10(-10) cm (-1) has been achieved. The spectrotemporal dynamics of a VECSEL in the 1030-nm wavelength region has been studied. The laser was operating cw at room temperature, with a baseline signal-to-noise ratio as high as 400. The laser was optically pumped with a threshold as low as 80 mW and was broadly tunable over a spectral range of approximately 75 nm .

  13. Spatio-temporal dynamics of a dual-wavelength vertical-external-cavity surface-emitting semiconductor laser

    SciTech Connect

    Morozov, Yu A; Konyukhov, A I; Kochkurov, L A; Morozov, M Yu

    2011-11-30

    A mathematical model of a dual-wavelength vertical-external-cavity surface-emitting laser (VECSEL) is formulated with the distribution of optical pumping and generated fields over the beam cross sections taken into account. Dynamic regimes are mapped using the 'pump power - cavity round-trip time' plane. The map comprises regions of cw generation, periodic oscillation, quasiperiodic and chaotic oscillations of the radiation intensity and the carrier density in the active regions of the laser. It is shown that when the reflection coefficient of the external cavity is increased, the regions of complex dynamics in the maps become narrower. Using numerical methods the spatio-temporal dynamics of a dualwavelength VECSEL is analysed in the regime of quasi-periodic oscillations.

  14. Highly Strained InGaAs/GaAs Multiwatt Vertical-External-Cavity Surface-Emitting Laser Emitting Around 1170 nm (Postprint)

    DTIC Science & Technology

    2007-09-01

    quantum wells in an optically pumped vertical-external-cavity surface-emitting laser VECSEL provide the broadband gain for the laser, result- ing... VECSELs provide wavelength agile laser sources through quantum confinement and a wide choice of constituent group II-VI and III-V ma- terial systems...the pro- portion of indium content. By means of intracavity frequency doubling of a VECSEL , the spectral range of 450–600 nm can be covered.3–8

  15. Operation of an optical in-well-pumped vertical-external-cavity surface-emitting laser

    SciTech Connect

    Zhang Wei; Ackemann, Thorsten; McGinily, Stephen; Schmid, Marc; Riis, Erling; Ferguson, Allister I

    2006-10-10

    We report the operation of an optical in-well-pumped vertical-external-cavity surface-emitting laser. The laser delivers 1 W at 855 nm and is pumped with a cost-effective fiber-coupled laser diode emitting at 806 nm. The laser modal gain is examined and ways of optimizing the system are investigated and discussed.

  16. Multiwatt-power highly-coherent compact single-frequency tunable vertical-external-cavity-surface-emitting-semiconductor-laser.

    PubMed

    Laurain, A; Myara, M; Beaudoin, G; Sagnes, I; Garnache, A

    2010-07-05

    We demonstrate high power (2.1W) low noise single frequency operation of a tunable compact verical-external-cavity surface-emitting- laser exhibiting a high beam quality. We took advantage of thermal lens-based stability to develop a short (3-10 mm) plano-plano external cavity without any intracavity filter. The semiconductor structure emitting at 1microm is optically pumped by a 8W commercial 808 nm multimode diode laser at large incidence angle. For heat management purpose the GaAs-based VECSEL membrane was bonded on a SiC substrate. We measured a low divergence quasi-circular TEM00 beam (M2 = 1.2) close to diffraction limit, with a linear light polarization (>30 dB).We simulated the steady state laser beam of this unstable cavity using Fresnel diffraction. The side mode suppression ratio is > 45 dB. The free running laser linewidth is 37 kHz limited by pump induced thermal fluctuations. Thanks to this high-Q external cavity approach, the frequency noise is low and the dynamics is in the relaxation-oscillation-free regime, exhibiting low intensity noise (< 0.1%), with a cutoff frequency approximately 41MHz above which the shot noise level is reached. The key parameters limiting the laser power and coherence are studied. This design/properties can be extended to other wavelengths.

  17. Vertical external cavity surface emitting PbTe/CdTe quantum dot lasers for the mid-infrared spectral region.

    PubMed

    Khiar, A; Eibelhuber, M; Volobuev, V; Witzan, M; Hochreiner, A; Groiss, H; Springholz, G

    2014-12-01

    Optically pumped vertical external cavity surface emitting lasers (VECSELS) emitting in the mid-infrared range are demonstrated with an active structure based on PbTe quantum dots (QDs) embedded in CdTe. In contrast to Stranski-Krastanov QDs, the PbTe QDs are fabricated by a strain-free synthesis method consisting of a molecular beam epitaxy growth step followed by a post-growth-annealing step. The laser emission of the VECSELs covers a wavelength range between 3.5 and 4.3 μm by changing the temperature from 85 to 240 K. The threshold power is lower than 100  mW(P) and the output power is more than 50  mW(P) at low temperature.

  18. Femtosecond synchronously in-well pumped vertical-external-cavity surface-emitting laser.

    PubMed

    Zhang, Wei; McDonald, Alison; Ackemann, Thorsten; Riis, Erling; McConnell, Gail

    2010-01-04

    We demonstrate the first synchronously in-well pumped vertical-external-cavity surface-emitting laser (VECSEL). Depending on the cavity mismatch, laser pulses with a duration from 1 ps to 7 ps at a repetition rate of 76 MHz were generated directly from the laser at 860 nm. The application of extra-cavity pulse compression further shortened the pulse to a duration of 210 fs providing a peak power of 226 W.

  19. Multichip Vertical-External-Cavity Surface-Emitting Lasers: A Coherent Power Scaling Scheme (Postprint)

    DTIC Science & Technology

    2006-12-01

    emitting laser ( VECSEL ), in which the waste heat generated in the active region is distributed on multi- VECSEL chips such that the pump level at the...thermal rollover is significantly increased. The advantages of this laser are discussed, and the development and demonstration of a two-chip VECSEL ...published November 22, 2006 We propose an efficient coherent power scaling scheme, the multichip vertical-external-cavity surface- emitting laser ( VECSEL ), in

  20. Multichip vertical-external-cavity surface-emitting lasers: a coherent power scaling scheme.

    PubMed

    Fan, Li; Fallahi, Mahmoud; Hader, Jörg; Zakharian, Aramais R; Moloney, Jerome V; Murray, James T; Bedford, Robert; Stolz, Wolfgang; Koch, Stephan W

    2006-12-15

    We propose an efficient coherent power scaling scheme, the multichip vertical-external-cavity surface-emitting laser (VECSEL), in which the waste heat generated in the active region is distributed on multi-VECSEL chips such that the pump level at the thermal rollover is significantly increased. The advantages of this laser are discussed, and the development and demonstration of a two-chip VECSEL operating around 970 nm with over 19 W of output power is presented.

  1. Vertical-cavity surface-emitting laser with liquid crystal external cavity

    NASA Astrophysics Data System (ADS)

    Xie, Y.; Beeckman, J.; Panajotov, K.; Neyts, K.

    2014-10-01

    We have developed a technology to integrate a thin layer of liquid crystal (LC) on top of a Vertical-Cavity Surface- Emitting Laser (VCSEL). Based on this technology, we demonstrate VCSELs with a chiral liquid crystal (CLC) layer, which acts as a tuneable mirror. The reflection properties of the CLC layer are controlled by temperature. Next we demonstrate VCSEL devices with tuneable external cavity using a nematic LC layer incorporated with an additional dielectric mirror (SiO2/Ta2O5). The VCSEL and the LC layer can be electrically driven independently and the optical length in the external cavity can be tuned by the applied voltage on the LC layer. In both configurations we show that the emission properties of the VCSEL can be changed, in terms of emission wavelength, polarization state and/or lasing threshold.

  2. High Brightness Spectral Beam Combination of High-Power Vertical-External-Cavity Surface-Emitting Lasers

    DTIC Science & Technology

    2006-05-31

    power vertical-external-cavity surface-emitting laser ( VECSEL ) using volume Bragg grating in a photo-thermo-re- fractive (PTR) glass is demonstrated...quality of each starting lasers was 1.68 and 1.35, and that of combined beam was 1.9. Scaling opportunities based on the parameters of VECSELs and PTR...Bragg gratings are discussed. Index Terms—Semiconductor laser, spectral combination, vertical-external-cavity surface-emitting laser ( VECSEL ), volume

  3. Advances in commercial, mode-locked vertical external cavity surface emitting lasers

    NASA Astrophysics Data System (ADS)

    Hempler, Nils; Lubeigt, Walter; Bialkowski, Bartlomiej; Hamilton, Craig J.; Maker, Gareth T.; Malcolm, Graeme P. A.

    2016-03-01

    In launching the Dragonfly, M Squared Lasers has successfully commercialized recent advances in mode-locked vertical external cavity surface emitting laser technologies operating between 920 nm - 1050 nm. This paper will describe the latest advances in the development of a new generation of Dragonfly lasers. The improved system has been engineered to utilise low-cost semiconductor gain media and integrated diode pumping, whilst exhibiting minimal footprint, diffraction limited beam quality and low intrinsic noise. Early experiments have resulted in pulses with 540mW of average output power and 150fs of duration at 200MHz pulse repetition frequency.

  4. Optimisation of fundamental transverse mode output in electrically pumped vertical external cavity surface emitting lasers

    NASA Astrophysics Data System (ADS)

    Jin, Xiao; Ivanov, Pavlo; Childs, David T. D.; Babazadeh, Nasser; Orchard, John; Stevens, Benjamin J.; Hogg, Richard A.

    2015-03-01

    In this work we report on the simulation of electrically pumped vertical external cavity surface emitting lasers (EP-VECSELs). We simulate an etched mesa structure (substrate emission) with the substrate acting as the current spreading layer. The effect of contact misalignment on the carrier distribution within the active element is explored and confirms the validity of the model in describing the carrier distribution. We go on to discuss the effects of the substrate thickness and trench depth on the intensity profile. Simulation results show that a thicker substrate and a trench partially etched into the substrate may improve the intensity profile in future devices.

  5. Design and characterization of electrically pumped vertical external cavity surface emitting lasers

    NASA Astrophysics Data System (ADS)

    Orchard, J. R.; Childs, D. T. D.; Lin, L. C.; Stevens, B. J.; Williams, D. M.; Hogg, R. A.

    2011-03-01

    The design of electrically pumped vertical external cavity surface emitting lasers (EP-VECSELs) for high power applications require a number of optimisations in design trade-offs, mainly that of doping for improved electrical performance and optical loss. Devices with diameter greater than 70μm and current spreading layer thickness of 100μm suffer from non-uniform carrier injection into the active region, below this diameter output power scales linearly with device area. We show CW powers of 133mW from a 150μm device with 4x1017cm-3 substrate doping at 0°C can be obtained.

  6. Design and Characterization of Optically Pumped Vertical Cavity Surface Emitting Lasers

    DTIC Science & Technology

    1992-12-01

    01 Design and Characterization of Optically Pumped Vertical Cavity Surface Emitting Lasers THESIS Presented to the Faculty of the School of Engineering...VCSELs ............................ 3-11 3.4 Injection Lasers : Electrical Pumping .................... 3-12 3.4.1 Active Region Design... lasers on the wafer. x Design and Characterization of Optically Pumped Vertical Cavity Surface Emitting Lasers L. Introduction This thesis investigates

  7. Femtosecond synchronously mode-locked vertical-external cavity surface-emitting laser.

    PubMed

    Zhang, Wei; Ackemann, Thorsten; Schmid, Marc; Langford, Nigel; Ferguson, Allister

    2006-03-06

    The behavior of a room temperature synchronously mode-locked vertical-external cavity surface-emitting laser (VECSEL) operating at 980 nm is reported. The laser performance was found to be qualitatively the same for different pump pulse duration (3.6 ps and 70 fs). The pulse duration of the laser is limited by strong self-phase modulation to around 10-40 ps. By compressing the strongly chirped pulses generated directly from the laser, ultrashort pulses with duration of around 200 fs with maximum peak powers of 1.3 kW at 80 MHz were obtained. Multiple pulsing of the laser was observed and the effects of cavity length detuning on pulse width and spectral bandwidth have been investigated.

  8. Design Rules and Characterisation of Electrically Pumped Vertical External Cavity Surface Emitting Lasers

    NASA Astrophysics Data System (ADS)

    Orchard, Jonathan R.; Childs, David T. D.; Chih Lin, Li; Stevens, Ben J.; Williams, David M.; Hogg, Richard A.

    2011-04-01

    We present an experimental study of the effect of substrate doping on the operating characteristics of substrate emitting electrically pumped vertical external cavity surface emitting lasers. We demonstrate a reduction in substrate doping from 2×1018 to 4×1017 cm-3 leads to reduced optical loss and enhanced current-gain characteristics. Spatial carrier distributions, evidenced by near field profiling of devices without external feedback indicates essentially identical behavior for the two substrate dopings. Devices with diameter greater than 100 µm and current spreading layer thickness of 100 µm suffer from non-uniform carrier injection into the active region, below this diameter output power scales linearly with device diameter. We show CW powers of 130 mW from a 100 µm device with 4×1017 cm-3 substrate doping at 0 °C can be obtained.

  9. Evolution of multi-mode operation in vertical-external-cavity surface-emitting lasers.

    PubMed

    Wichmann, Matthias; Shakfa, Mohammad Khaled; Zhang, Fan; Heinen, Bernd; Scheller, Maik; Rahimi-Iman, Arash; Stolz, Wolfgang; Moloney, Jerome V; Koch, Stephan W; Koch, Martin

    2013-12-30

    The longitudinal multi-mode emission in a vertical-external-cavity surface-emitting laser is investigated using both single shot streak camera measurements and interferometric measurement techniques. For this, the laser is operated in the single- and two-color emission regime using both an etalon and a free-running configuration without etalon, respectively. The laser emission is analyzed with respect to pump power and output coupling losses for a long and for a short resonator. We observe a steep increase of emission bandwidth close to the laser threshold and monitor the transition between longitudinal single- and multi-mode operation. Additionally, the results indicate that a stable two-color operation is related to a sufficiently high number of oscillating longitudinal modes within each color.

  10. Absorber and gain chip optimization to improve performance from a passively modelocked electrically pumped vertical external cavity surface emitting laser

    SciTech Connect

    Zaugg, C. A. Mangold, M.; Pallmann, W. P.; Golling, M.; Tilma, B. W.; Keller, U.; Gronenborn, S.; Moench, H.; Weichmann, U.; Miller, M.

    2014-03-24

    We present an electrically pumped vertical-external-cavity surface-emitting laser (EP-VECSEL) modelocked with a semiconductor saturable absorber mirror (SESAM) with significantly improved performance. In different cavity configurations, we present the shortest pulses (2.5 ps), highest average output power (53.2 mW), highest repetition rate (18.2 GHz), and highest peak power (4.7 W) to date. The simple and low-cost concept of EP-VECSELs is very attractive for mass-market applications such as optical communication and clocking. The improvements result from an optimized gain chip from Philips Technologie GmbH and a SESAM, specifically designed for EP-VECSELs. For the gain chip, we found a better trade-off between electrical and optical losses with an optimized doping scheme in the substrate to increase the average output power. Furthermore, the device's bottom contact diameter (60 μm) is smaller than the oxide aperture diameter (100 μm), which favors electro-optical conversion into a TEM{sub 00} mode. Compared to optically pumped VECSELs we have to increase the field enhancement in the active region of an EP-VECSEL which requires a SESAM with lower saturation fluence and higher modulation depth for modelocking. We therefore used a resonant quantum well SESAM with a 3.5-pair dielectric top-coating (SiN{sub x} and SiO{sub 2}) to enhance the field in the absorber at the lasing wavelength of 980 nm. The absorption bandedge at room temperature is detuned (965 nm) compared to the resonance (980 nm), which enables temperature-tuning of the modulation depth and saturation fluence from approximately 2.5% up to 15% and from 20 μJ/cm{sup 2} to 1.1 μJ/cm{sup 2}, respectively.

  11. Absorber and gain chip optimization to improve performance from a passively modelocked electrically pumped vertical external cavity surface emitting laser

    NASA Astrophysics Data System (ADS)

    Zaugg, C. A.; Gronenborn, S.; Moench, H.; Mangold, M.; Miller, M.; Weichmann, U.; Pallmann, W. P.; Golling, M.; Tilma, B. W.; Keller, U.

    2014-03-01

    We present an electrically pumped vertical-external-cavity surface-emitting laser (EP-VECSEL) modelocked with a semiconductor saturable absorber mirror (SESAM) with significantly improved performance. In different cavity configurations, we present the shortest pulses (2.5 ps), highest average output power (53.2 mW), highest repetition rate (18.2 GHz), and highest peak power (4.7 W) to date. The simple and low-cost concept of EP-VECSELs is very attractive for mass-market applications such as optical communication and clocking. The improvements result from an optimized gain chip from Philips Technologie GmbH and a SESAM, specifically designed for EP-VECSELs. For the gain chip, we found a better trade-off between electrical and optical losses with an optimized doping scheme in the substrate to increase the average output power. Furthermore, the device's bottom contact diameter (60 μm) is smaller than the oxide aperture diameter (100 μm), which favors electro-optical conversion into a TEM00 mode. Compared to optically pumped VECSELs we have to increase the field enhancement in the active region of an EP-VECSEL which requires a SESAM with lower saturation fluence and higher modulation depth for modelocking. We therefore used a resonant quantum well SESAM with a 3.5-pair dielectric top-coating (SiNx and SiO2) to enhance the field in the absorber at the lasing wavelength of 980 nm. The absorption bandedge at room temperature is detuned (965 nm) compared to the resonance (980 nm), which enables temperature-tuning of the modulation depth and saturation fluence from approximately 2.5% up to 15% and from 20 μJ/cm2 to 1.1 μJ/cm2, respectively.

  12. Impact of strain on periodic gain structures in vertical external cavity surface-emitting lasers

    NASA Astrophysics Data System (ADS)

    Jasik, Agata; Sokół, Adam Kacper; Broda, Artur; Sankowska, Iwona; Wójcik-Jedlińska, Anna; Wasiak, Michał; Trajnerowicz, Artur; Kubacka-Traczyk, Justyna; Muszalski, Jan

    2016-10-01

    In this article, the impact of strain relaxation on the emission properties of InGaAs/GaAs multiple quantum wells without strain compensation was examined. Structures consisting of different numbers of quantum wells, namely 4, 8, 12 and 16, on top of distributed Bragg reflectors were grown by molecular beam epitaxy as a typical vertical external cavity surface-emitting laser (VECSEL). The relation between emission parameters in the lasing regime and strain relaxation were investigated. A two-step control of the growth rate allowed for obtaining fixed spectral detuning in all structures regardless of the number of quantum wells. The heterostructures varied in its strain and the microcavity length. The other parameters remained unchanged. In consequence, for the first time a unique set of VECSEL-like heterostructures was investigated. The strain was analyzed by reciprocal space mapping using high-resolution X-ray diffractometry. It was found that the degree of structure relaxation caused by misfit dislocation generation depends linearly on the number of quantum wells. By fitting numerical simulations to the experimental results, we have quantitatively determined the extent to which output power was suppressed by increase in non-radiative recombination arising from misfit dislocations. The non-radiative coefficients were determined. Taking output power as a criterion, we determined the optimal number of QWs to be 12 and the maximum tolerable relaxation value of 0.27 for InGaAs/GaAs VECSEL structures with uniformly distributed quantum wells in microcavity. The dependence of the monomolecular recombination coefficient on structure relaxation has been determined.

  13. Spectral condensation near molecular transitions in intracavity laser spectroscopy with vertical external cavity surface emitting lasers

    NASA Astrophysics Data System (ADS)

    Bertseva, Elena; Campargue, Alain

    2004-03-01

    Vertical external cavity surface emitting lasers (VeCSELs) are ideal amplification media for intracavity laser absorption spectroscopy (ICLAS) around 1 μm. However, we noted that, in some spectra recorded by ICLAS-VeCSEL, the observed line profiles of very weak overtone transitions were clearly asymmetric, this distortion being more pronounced for the strongest lines. More spectacular effects were observed when we investigated the acetylene spectrum: while the weakest absorption lines appeared as dips superimposed on the baseline as usual in ICLAS, the strongest lines mostly disappeared and were replaced by emission lines slightly blue shifted from the absorption line center. This effect, called "spectral condensation", was, in fact, discovered near atomic transitions, more than 30 years ago, using pulsed lasers. Using acetylene and water as absorbers, we have systematically studied the different factors of importance for spectral condensation and showed that it increases with the pumping rate, the generation time and the line intensity. Spectral condensation was also found to increase with the pressure of the intracavity gas sample up to a value of a few Torrs, and to decrease afterwards. The appearance of spectral condensation has been shown to be highly correlated to time oscillations of the total laser power. Of importance for intensity measurements, this systematic study has showed that condensation effects may appear for long generation times even at low pumping rate and even with extremely weak absorption lines. A discussion of the results in relation with different interpretations available in the literature is presented with a particular emphasis on the theory based on the coherent interaction of electro-magnetic field with optically dense resonant extended medium leading to a parametrical amplification without population inversion.

  14. Analysis and Characterization of the Small-Signal Modulation of a Vertical External Cavity Surface Emitting Laser (POSTPRINT)

    DTIC Science & Technology

    2010-02-01

    modulation of a vertical external cavity surface emitting laser ( VECSEL ) is examined. The modulation transfer function (MTF) of the cavity is measured for...to mathematically describe the time-dependant VECSEL response. We present a series of measurements that provide important laser parameters such as...internal device losses and differential gain. The VECSEL operating in this regime is an overdamped oscillator and has free-running characteristics that

  15. Grating-based wavelength control of single- and two-color vertical-external-cavity-surface-emitting lasers.

    PubMed

    Scheller, Maik; Koch, Stephan W; Moloney, Jerome V

    2012-01-01

    Wide wavelength tunability of single- and two-color operating vertical-external-cavity-surface-emitting lasers (VECSELs) is demonstrated. Employing an external feedback based on a diffractive grating outside the cavity of a narrow-line single-color VECSEL allows for a continuous tuning of the emission wavelength over 10 nm. Employing a dual-feedback-configuration for tunable two-color emission, a tunability of the difference frequency between the two lasing wavelengths from 300 gigahertz to up to 3.5 terahertz is demonstrated.

  16. Exploring ultrafast negative Kerr effect for mode-locking vertical external-cavity surface-emitting lasers.

    PubMed

    Albrecht, Alexander R; Wang, Yi; Ghasemkhani, Mohammadreza; Seletskiy, Denis V; Cederberg, Jeffrey G; Sheik-Bahae, Mansoor

    2013-11-18

    We present analytical considerations of "self-mode-locked" operation in a typical vertical external-cavity surface-emitting laser (VECSEL) cavity geometry by means of Kerr lens action in the semiconductor gain chip. We predict Kerr-lens mode-locked operation for both soft- and hard-apertures placed at the optimal intra-cavity positions. These predictions are experimentally verified in a Kerr-lens mode-locked VECSEL capable of producing pulse durations of below 500 fs at 1 GHz repetition rate.

  17. Development of vertical external cavity surface emitting lasers (VECSELs) for use as monochromatic and polychromatic sodium guidestars

    NASA Astrophysics Data System (ADS)

    Hackett, Shawn; Albrecht, Alexander R.; Yang, Zhou; Cederberg, Jeffrey G.; Sheik-Bahae, Mansoor; McGraw, John T.; Johnson, Robert L.; Richey, Jeff W.

    2016-07-01

    The work of Pique showed that multiple guidestars emitting at 1140 nm and 589 nm simultaneously could be utilized to correct for Tip and Tilt aberrations [1]. Such a guidestar is hence known as a PLGS (Polychromatic Laser Guidestar). However, no current high power (> 5W) narrow bandwidth (< 1GHz) exist for 1140 nm emission. A Vertical External Cavity Surface Emitting Laser (VECSEL) is shown with high power > 12W and narrow bandwidth emission which has been successfully used to pump the sodium 3P3/2 to 4S1/2 sodium transition as a testbed for the development of a CW PLGS system.

  18. Self-mode-locked quantum-dot vertical-external-cavity surface-emitting laser.

    PubMed

    Gaafar, Mahmoud; Nakdali, Dalia Al; Möller, Christoph; Fedorova, Ksenia A; Wichmann, Matthias; Shakfa, Mohammad Khaled; Zhang, Fan; Rahimi-Iman, Arash; Rafailov, Edik U; Koch, Martin

    2014-08-01

    We present the first self-mode-locked optically pumped quantum-dot semiconductor disk laser. Our mode-locked device emits sub-picosecond pulses at a wavelength of 1040 nm and features a record peak power of 460 W at a repetition rate of 1.5 GHz. In this work, we also investigate the temperature dependence of the pulse duration as well as the time-bandwidth product for stable mode locking.

  19. Dynamics of a low-threshold optically pumped organic vertical-cavity surface-emitting laser

    NASA Astrophysics Data System (ADS)

    Shayesteh, Mohammad Reza; Darvish, Ghafar

    2016-06-01

    We propose a low-threshold optically pumped organic vertical-cavity surface-emitting laser (OVCSEL). This device has the capability to apply both electrical and optical excitation. The microcavity structure consists of an organic light emitting diode with field-effect electron transport inserted in a high-quality factor double distributed Bragg reflector. The simulated quality factor of the microcavity is shown to be as high as 16,000. Also, we investigate threshold behaviour and the dynamics of the optically pumped OVCSEL with sub-picosecond pulses. Results from numerical simulation show that lasing threshold is 12.8 pJ/0.64 µJ cm-2 when pumped by sub-picosecond pulses of λ = 400 nm wavelength light.

  20. Carbon nanotube mode-locked vertical external-cavity surface-emitting laser

    NASA Astrophysics Data System (ADS)

    Seger, K.; Meiser, N.; Choi, S. Y.; Jung, B. H.; Yeom, D.-I.; Rotermund, F.; Okhotnikov, O.; Laurell, F.; Pasiskevicius, V.

    2014-03-01

    Mode-locking an optically pumped semiconductor disk laser has been demonstrated using low-loss saturable absorption containing a mixture of single-walled carbon nanotubes in PMM polymer. The modulator was fabricated by a simple spin-coating technique on fused silica substrate and was operating in transmission. Stable passive fundamental modelocking was obtained at a repetition rate of 613 MHz with a pulse length of 1.23 ps. The mode-locked semiconductor disk laser in a compact geometry delivered a maximum average output power of 136 mW at 1074 nm.

  1. Lead-chalcogenide mid-infrared vertical external cavity surface emitting lasers with improved threshold: Theory and experiment

    SciTech Connect

    Fill, Matthias; Debernardi, Pierluigi; Felder, Ferdinand; Zogg, Hans

    2013-11-11

    Mid-infrared Vertical External Cavity Surface Emitting Lasers (VECSEL) based on narrow gap lead-chalcogenide (IV-VI) semiconductors exhibit strongly reduced threshold powers if the active layers are structured laterally for improved optical confinement. This is predicted by 3-d optical calculations; they show that lateral optical confinement is needed to counteract the anti-guiding features of IV-VIs due to their negative temperature dependence of the refractive index. An experimental proof is performed with PbSe quantum well based VECSEL grown on a Si-substrate by molecular beam epitaxy and emitting around 3.3 μm. With proper mesa-etching, the threshold intensity is about 8-times reduced.

  2. Highly efficient, diffraction-limited laser emission from a vertical external-cavity surface-emitting organic laser.

    PubMed

    Rabbani-Haghighi, Hadi; Forget, Sébastien; Chénais, Sébastien; Siove, Alain

    2010-06-15

    We report on a solid-state laser structure functioning as the organic counterpart of a vertical external-cavity surface-emitting laser (VECSEL) design. The gain medium is a poly(methyl methacrylate) film doped with Rhodamine 640, spin casted onto the high-reflectivity mirror of a plano-concave resonator. Upon pumping by 7 ns pulses at 532 nm, a diffraction-limited beam (M(2)=1) was obtained, with a conversion efficiency of 43%; higher peak powers (2 kW) could be attained when resorting to shorter (0.5 ns) pump pulses. The spectrum was controlled by the thickness of the active layer playing the role of an intracavity etalon; tunability is demonstrated at over and up to 20 nm.

  3. In-well pumped mid-infrared PbTe/CdTe quantum well vertical external cavity surface emitting lasers

    SciTech Connect

    Khiar, A. Witzan, M.; Hochreiner, A.; Eibelhuber, M.; Springholz, G.; Volobuev, V.

    2014-06-09

    Optical in-well pumped mid-infrared vertical external cavity surface emitting lasers based on PbTe quantum wells embedded in CdTe barriers are realized. In contrast to the usual ternary barrier materials of lead salt lasers such as PbEuTe of PbSrTe, the combination of narrow-gap PbTe with wide-gap CdTe offers an extremely large carrier confinement, preventing charge carrier leakage from the quantum wells. In addition, optical in-well pumping can be achieved with cost effective and readily available near infrared lasers. Free carrier absorption, which is a strong loss mechanism in the mid-infrared, is strongly reduced due to the insulating property of CdTe. Lasing is observed from 85 K to 300 K covering a wavelength range of 3.3–4.2 μm. The best laser performance is achieved for quantum well thicknesses of 20 nm. At low temperature, the threshold power is around 100 mW{sub P} and the output power more than 700 mW{sub P}. The significance of various charge carrier loss mechanisms are analyzed by modeling the device performance. Although Auger losses are quite low in IV–VI semiconductors, an Auger coefficient of C{sub A} = 3.5 × 10{sup −27} cm{sup 6} s{sup −1} was estimated for the laser structure, which is attributed to the large conduction band offset.

  4. Over 3 W high-efficiency vertical-external-cavity surface-emitting lasers and application as efficient fiber laser pump sources

    NASA Astrophysics Data System (ADS)

    Fan, L.; Fallahi, M.; Hader, J.; Zakharian, A. R.; Kolesik, M.; Moloney, J. V.; Qiu, T.; Schülzgen, A.; Peyghambarian, N.; Stolz, W.; Koch, S. W.; Murray, J. T.

    2005-05-01

    We report on the design and fabrication of high-power, high-brightness diode-pumped vertical-external-cavity surface-emitting lasers. Over 3 W continuous wave fundamental transverse mode (TEM00) output at 980 nm with a high slope efficiency of 44% is demonstrated at room temperature. The diffraction-limited beam with M2 factor of 1.15 at high-power operation is achieved. A vertical-external-cavity surface-emitting laser operating near 976 nm with a diffraction-limited beam is used to pump the core of 3 cm long Er /Yb-codoped single-mode phosphate fiber lasers. An output power in excess of 250 mW at 1535 nm with a slope efficiency of 29% is obtained without any cooling.

  5. Highly Strained InGaAs/GaAs Multiwatt Vertical-External-Cavity Surface-Emitting Laser Emitting Around 1170nm (Postprint)

    DTIC Science & Technology

    2007-09-01

    pumped vertical-external-cavity surface-emitting laser VECSEL provide the broadband gain for the laser, result- ing in a large wavelength tuning...range.1 Since the quantum well QW gain spectra can be accurately designed by using fully microscopic many-body model,2 VECSELs provide wavelength...content. By means of intracavity frequency doubling of a VECSEL , the spectral range of 450–600 nm can be covered.3–8 Considerable effort has been devoted

  6. Intra-cavity cryogenic optical refrigeration using high power vertical external-cavity surface-emitting lasers (VECSELs).

    PubMed

    Ghasemkhani, Mohammadreza; Albrecht, Alexander R; Melgaard, Seth D; Seletskiy, Denis V; Cederberg, Jeffrey G; Sheik-Bahae, Mansoor

    2014-06-30

    A 7% Yb:YLF crystal is laser cooled to 131 ± 1 K from room temperature by placing it inside the external cavity of a high power InGaAs/GaAs VECSEL operating at 1020 nm with 0.15 nm linewidth. This is the lowest temperature achieved in the intracavity geometry to date and presents major progress towards realizing an all-solid-state compact optical cryocooler.

  7. Ultrafast and widely tuneable vertical-external-cavity surface-emitting laser, mode-locked by a graphene-integrated distributed Bragg reflector.

    PubMed

    Zaugg, C A; Sun, Z; Wittwer, V J; Popa, D; Milana, S; Kulmala, T S; Sundaram, R S; Mangold, M; Sieber, O D; Golling, M; Lee, Y; Ahn, J H; Ferrari, A C; Keller, U

    2013-12-16

    We report a versatile way of controlling the unsaturated loss, modulation depth and saturation fluence of graphene-based saturable absorbers (GSAs), by changing the thickness of a spacer between a single layer graphene (SLG) and a high-reflection mirror. This allows us to modulate the electric field intensity enhancement at the GSA from 0 up to 400%, due to the interference of incident and reflected light at the mirror. The unsaturated loss of the SLG-mirror-assembly can be reduced to ∼0. We use this to mode-lock a vertical-external-cavity surface-emitting laser (VECSEL) from 935 to 981 nm. This approach can be applied to integrate SLG into various optical components, such as output coupler mirrors, dispersive mirrors or dielectric coatings on gain materials. Conversely, it can also be used to increase the absorption (up to 10%) in various graphene based photonics and optoelectronics devices, such as photodetectors.

  8. Vertical-external-cavity surface-emitting 625-nm laser upon optical pumping of an InGaP/AlGaInP nanostructure with a Bragg mirror

    SciTech Connect

    Kozlovskii, Vladimir I; Lavrushin, B M; Skasyrsky, Yan K; Tiberi, M D

    2009-08-31

    Pulsed lasing is obtained in a multilayer quantum-well InGaP/AlGaInP structure in a cavity with an external mirror and a Bragg AlAs/AlGaAs mirror pumped by the 532-nm second harmonic from a diode-pumped Q-switched Nd:YAG laser. Lasing is obtained at the TEM{sub 00} fundamental transverse mode of the cavity at a wavelength of 625 nm. The pulse beam power was 3.1 W and the radiation divergence achieved a diffraction limit of 10-12 mrad for 5-ns pulses with a repetition rate of 6 kHz. (lasers)

  9. Metasurface external cavity laser

    SciTech Connect

    Xu, Luyao Curwen, Christopher A.; Williams, Benjamin S.; Hon, Philip W. C.; Itoh, Tatsuo; Chen, Qi-Sheng

    2015-11-30

    A vertical-external-cavity surface-emitting-laser is demonstrated in the terahertz range, which is based upon an amplifying metasurface reflector composed of a sub-wavelength array of antenna-coupled quantum-cascade sub-cavities. Lasing is possible when the metasurface reflector is placed into a low-loss external cavity such that the external cavity—not the sub-cavities—determines the beam properties. A near-Gaussian beam of 4.3° × 5.1° divergence is observed and an output power level >5 mW is achieved. The polarized response of the metasurface allows the use of a wire-grid polarizer as an output coupler that is continuously tunable.

  10. 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.

  11. 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.

  12. Highly efficient optically pumped vertical-emitting semiconductor laser with more than 20 W average output power in a fundamental transverse mode.

    PubMed

    Rudin, B; Rutz, A; Hoffmann, M; Maas, D J H C; Bellancourt, A-R; Gini, E; Südmeyer, T; Keller, U

    2008-11-15

    We have demonstrated an optically pumped vertical-external-cavity surface-emitting laser (OP-VECSEL) generating more than 20 W of cw output power in a fundamental transverse mode (M2 approximately 1.1) at 960 nm. The laser is highly efficient with a slope efficiency of 49%, a pump threshold of 4.4 W, and an overall optical-to-optical efficiency of 43%.

  13. LASERS: Vertical-external-cavity surface-emitting 625-nm laser upon optical pumping of an InGaP/AlGaInP nanostructure with a Bragg mirror

    NASA Astrophysics Data System (ADS)

    Kozlovskii, Vladimir I.; Lavrushin, B. M.; Skasyrsky, Yan K.; Tiberi, M. D.

    2009-08-01

    Pulsed lasing is obtained in a multilayer quantum-well InGaP/AlGaInP structure in a cavity with an external mirror and a Bragg AlAs/AlGaAs mirror pumped by the 532-nm second harmonic from a diode-pumped Q-switched Nd:YAG laser. Lasing is obtained at the TEM00 fundamental transverse mode of the cavity at a wavelength of 625 nm. The pulse beam power was 3.1 W and the radiation divergence achieved a diffraction limit of 10-12 mrad for 5-ns pulses with a repetition rate of 6 kHz.

  14. Degradation studies and pump optimization of optically pumped red-emitting AlGaInP-VECSELs

    NASA Astrophysics Data System (ADS)

    Kahle, Hermann; Mateo, Cherry M. N.; Jäger, Maren; Weinspach, Karoline; Baumgärtner, Stefan; Brauch, Uwe; Bek, Roman; Schwarzbäck, Thomas; Jetter, Michael; Graf, Thomas; Michler, Peter

    2015-03-01

    Optically pumped semiconductor (OPS) vertical external-cavity surface-emitting lasers (VECSELs) are an important category of power scalable lasers with a wide range of applications in biophotonics, medicine technologies, spectroscopy, projector technologies and lithography. The open laser resonator allows to implement frequency selective and converting intra-cavity elements. The possibility of bandgap engineering, laser emission in the fundamental Gaussian mode and the technical simplicity leads to ongoing growth of the area of applications for these tunable laser sources. We present degradation studies of metal-organic vapor-phase epitaxy (MOVPE) grown, optically pumped, red-emitting AlGaInP-VECSELs with quantum wells (QWs) as active layers. Laser performance in continuous operation, pumped with a 532nm Nd:YAG laser and recorded over several hours, will be shown. Surface investigations of the gain structure via large-area photoluminescence maps show the possible consequences of optical pumping. A comparison of barrier-pumped performance data with the data of an in-well pumped VECSEL device is shown.

  15. VCSEL's frequency stabilization of an external cavity diode laser: countermeasures against atmospheric temperature variations

    NASA Astrophysics Data System (ADS)

    Motojima, Mutsuki; Doi, Kohei; Sato, Takashi; Ohkawa, Masashi; Suzuki, Takamasa

    2010-02-01

    We introduced the vertical cavity surface emitting laser (VCSEL) as the laser diode in tour external cavity system. Because VCSELs are now commercially available, and the External cavity diode laser (ECDL) systems using them are expected to improve their frequency stability, we have replaced a Fabry-Perot type laser diode with a VCSEL, and examined its oscillation-frequency stability. Therefore we were able to expect that the VCSELs with our double optical feedback system have good oscillation frequency stability. The obtained VCSEL's oscillation-frequency stability, i.e., the square root of Allan variance σ was 4×10-10, at an averaging time of τ=1 sec.

  16. Discrete wavelength-locked external cavity laser

    NASA Technical Reports Server (NTRS)

    Pilgrim, Jeffrey S. (Inventor); Silver, Joel A. (Inventor)

    2005-01-01

    An external cavity laser (and method of generating laser light) comprising: a laser light source; means for collimating light output by the laser light source; a diffraction grating receiving collimated light; a cavity feedback mirror reflecting light received from the diffraction grating back to the diffraction grating; and means for reliably tuning the external cavity laser to discrete wavelengths.

  17. Scalable high-power optically pumped GaAs laser

    NASA Astrophysics Data System (ADS)

    Le, H. Q.; di Cecca, S.; Mooradian, A.

    1991-05-01

    The use of disk geometry, optically pumped semiconductor gain elements for high-power scalability and good transverse mode quality has been studied. A room-temperature TEM00 transverse mode, external-cavity GaAs disk laser has been demonstrated with 500 W peak-power output and 40-percent slope efficiency, when pumped by a Ti:Al2O3 laser. The conditions for diode laser pumping are shown to be consistent with available power level.

  18. Linearly Polarized Dual-Wavelength Vertical-External-Cavity Surface-Emitting Laser (Postprint)

    DTIC Science & Technology

    2007-03-01

    emitting la- ser VECSEL was conducted recently.1 This laser is based on a complicated design and a critical epitaxial growth of the VECSEL chip...However, its lasing spectrum at each color is a few nanometer wide and the laser also indicates self-pulsation. It is possible for a traditional VECSEL ...a relatively flat peak. Second, the VECSEL gain medium is inhomogeneously broadened due to the electron-phonon interaction, the width and composition

  19. Ultrafast pulse amplification in mode-locked vertical external-cavity surface-emitting lasers

    SciTech Connect

    Böttge, C. N. Hader, J.; Kilen, I.; Moloney, J. V.; Koch, S. W.

    2014-12-29

    A fully microscopic many-body Maxwell–semiconductor Bloch model is used to investigate the influence of the non-equilibrium carrier dynamics on the short-pulse amplification in mode-locked semiconductor microlaser systems. The numerical solution of the coupled equations allows for a self-consistent investigation of the light–matter coupling dynamics, the carrier kinetics in the saturable absorber and the multiple-quantum-well gain medium, as well as the modification of the light field through the pulse-induced optical polarization. The influence of the pulse-induced non-equilibrium modifications of the carrier distributions in the gain medium and the saturable absorber on the single-pulse amplification in the laser cavity is identified. It is shown that for the same structure, quantum wells, and gain bandwidth the non-equilibrium carrier dynamics lead to two preferred operation regimes: one with pulses in the (sub-)100 fs-regime and one with multi-picosecond pulses. The recovery time of the saturable absorber determines in which regime the device operates.

  20. Mode stability of external cavity diode lasers.

    PubMed

    Saliba, Sebastian D; Junker, Mark; Turner, Lincoln D; Scholten, Robert E

    2009-12-10

    Mode stability is an important performance characteristic of external cavity diode lasers (ECDLs). It has been well established that the continuous mode-hop-free tuning range of a grating-feedback ECDL can be optimized by rotating the grating about a specific pivot location. We show that similar results can be obtained for other more convenient pivot locations by choosing instead the cavity length and grating location. The relative importance of the temperature stability of the diode and of the external cavity is also evaluated. We show that mechanically simple ECDL designs, using mostly standard components, can readily achieve a 35 GHz mode-hop-free tuning range at 780 nm.

  1. Blue-emitting external cavity laser diode

    NASA Astrophysics Data System (ADS)

    Na, Hong Man; Song, Hong Joo; Park, Jong Hwan; Lee, Jun Ho; Park, Jung Ho

    2016-03-01

    An front facet anti-reflection coated solitary laser diode is operated in the external cavity diode laser (ECDL). For wavelength stabilization and narrow spectral width, the diffraction grating is used in a Littrow configuration. At an injection current of 280 mA, a output power of 35mW with a slope efficiency of 0.22 W/A and the bandwidth of 80 pm at a wavelength of 457 nm. In this paper, the tunable external cavity diode laser module is designed with an overall size of 18 mm x 24 mm x 14 mm. ECDL showed excellent wavelength locking behavior without a non-shift of the peak wavelength.

  2. Cover slip external cavity diode laser.

    PubMed

    Carr, Adra V; Sechrest, Yancey H; Waitukaitis, Scott R; Perreault, John D; Lonij, Vincent P A; Cronin, Alexander D

    2007-10-01

    A 671 nm diode laser with a mode-hop-free tuning range of 40 GHz is described. This long tuning range is achieved by simultaneously ramping the external cavity length with the laser injection current. The laser output pointing remains fixed, independent of its frequency because of the cover slip cavity design. This system is simple, economical, robust, and easy to use for spectroscopy, as we demonstrate with lithium vapor and lithium atom beam experiments.

  3. Oscillation frequency stabilization and narrowing of a laser diode by using an external cavity

    NASA Astrophysics Data System (ADS)

    Iwahori, Minoru; Doi, Kohei; Arai, Hideaki; Sato, Takashi; Ohkawa, Masashi

    2012-02-01

    External cavity diode laser (ECDL) systems are presently experiencing a surge in popularity as laser light-sources, in advanced optical communications- and measurement-applications. Because such systems require that their external reflectors be precisely controlled, to eliminate low frequency fluctuations in optical output, we conducted experiments with a two-cavity version of the ECDL system for a vertical cavity surface emitting laser (VCSEL). This technique brings the added advantages of a narrower linewidth than would be achievable via a single optical feedback. VCSELs are characterized by wider oscillation linewidths than edge emitting types, so the larger effect of double optical feedback system is expected.

  4. Broadband External-Cavity Diode Laser

    NASA Technical Reports Server (NTRS)

    Pilgrim, Jeffrey S.

    2005-01-01

    A broadband external-cavity diode laser (ECDL) has been invented for use in spectroscopic surveys preparatory to optical detection of gases. Heretofore, commercially available ECDLs have been designed, in conjunction with sophisticated tuning assemblies, for narrow- band (and, typically, single-frequency) operation, as needed for high sensitivity and high spectral resolution in some gas-detection applications. However, for preparatory spectroscopic surveys, high sensitivity and narrow-band operation are not needed; in such cases, the present broadband ECDL offers a simpler, less-expensive, more-compact alternative to a commercial narrowband ECDL.

  5. Porous photonic crystal external cavity laser biosensor

    SciTech Connect

    Huang, Qinglan; Peh, Jessie; Hergenrother, Paul J.; Cunningham, Brian T.

    2016-08-15

    We report the design, fabrication, and testing of a photonic crystal (PC) biosensor structure that incorporates a porous high refractive index TiO{sub 2} dielectric film that enables immobilization of capture proteins within an enhanced surface-area volume that spatially overlaps with the regions of resonant electromagnetic fields where biomolecular binding can produce the greatest shifts in photonic crystal resonant wavelength. Despite the nanoscale porosity of the sensor structure, the PC slab exhibits narrowband and high efficiency resonant reflection, enabling the structure to serve as a wavelength-tunable element of an external cavity laser. In the context of sensing small molecule interactions with much larger immobilized proteins, we demonstrate that the porous structure provides 3.7× larger biosensor signals than an equivalent nonporous structure, while the external cavity laser (ECL) detection method provides capability for sensing picometer-scale shifts in the PC resonant wavelength caused by small molecule binding. The porous ECL achieves a record high figure of merit for label-free optical biosensors.

  6. Plasmonic external cavity laser refractometric sensor

    PubMed Central

    Zhang, Meng; Lu, Meng; Ge, Chun; Cunningham, Brian T.

    2014-01-01

    Combining the high sensitivity properties of surface plasmon resonance refractive index sensing with a tunable external cavity laser, we demonstrate a plasmonic external cavity laser (ECL) for high resolution refractometric sensing. The plasmonic ECL utilizes a plasmonic crystal with extraordinary optical transmission (EOT) as the wavelength-selective element, and achieves single mode lasing at the transmission peak of the EOT resonance. The plasmonic ECL refractometric sensor maintains the high sensitivity of a plasmonic crystal sensor, while simultaneously providing a narrow spectral linewidth through lasing emission, resulting in a record high figure of merit for refractometric sensing with an active or passive optical resonator. We demonstrate single-mode and continuous-wave operation of the electrically-pumped laser system, and show the ability to measure refractive index changes with a 3σ detection limit of 1.79 × 10−6 RIU. The demonstrated approach is a promising path towards label-free optical biosensing with enhanced signal-to-noise ratios for challenging applications in small molecule drug discovery and pathogen sensing. PMID:25321243

  7. Porous photonic crystal external cavity laser biosensor

    NASA Astrophysics Data System (ADS)

    Huang, Qinglan; Peh, Jessie; Hergenrother, Paul J.; Cunningham, Brian T.

    2016-08-01

    We report the design, fabrication, and testing of a photonic crystal (PC) biosensor structure that incorporates a porous high refractive index TiO2 dielectric film that enables immobilization of capture proteins within an enhanced surface-area volume that spatially overlaps with the regions of resonant electromagnetic fields where biomolecular binding can produce the greatest shifts in photonic crystal resonant wavelength. Despite the nanoscale porosity of the sensor structure, the PC slab exhibits narrowband and high efficiency resonant reflection, enabling the structure to serve as a wavelength-tunable element of an external cavity laser. In the context of sensing small molecule interactions with much larger immobilized proteins, we demonstrate that the porous structure provides 3.7× larger biosensor signals than an equivalent nonporous structure, while the external cavity laser (ECL) detection method provides capability for sensing picometer-scale shifts in the PC resonant wavelength caused by small molecule binding. The porous ECL achieves a record high figure of merit for label-free optical biosensors.

  8. Porous photonic crystal external cavity laser biosensor.

    PubMed

    Huang, Qinglan; Peh, Jessie; Hergenrother, Paul J; Cunningham, Brian T

    2016-08-15

    We report the design, fabrication, and testing of a photonic crystal (PC) biosensor structure that incorporates a porous high refractive index TiO2 dielectric film that enables immobilization of capture proteins within an enhanced surface-area volume that spatially overlaps with the regions of resonant electromagnetic fields where biomolecular binding can produce the greatest shifts in photonic crystal resonant wavelength. Despite the nanoscale porosity of the sensor structure, the PC slab exhibits narrowband and high efficiency resonant reflection, enabling the structure to serve as a wavelength-tunable element of an external cavity laser. In the context of sensing small molecule interactions with much larger immobilized proteins, we demonstrate that the porous structure provides 3.7× larger biosensor signals than an equivalent nonporous structure, while the external cavity laser (ECL) detection method provides capability for sensing picometer-scale shifts in the PC resonant wavelength caused by small molecule binding. The porous ECL achieves a record high figure of merit for label-free optical biosensors.

  9. External-cavity solid-state organic lasers: Design rules and application perspectives (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Chénais, Sébastien; Gallinelli, Thomas; Mhibik, Oussama; Blanchard, Cédric; Forget, Sébastien

    2016-09-01

    Among various laser architectures currently used to make lasers out of organic materials (distributed feedback lasers or organic vertical cavity surface-emitting lasers, ....), vertical EXTERNAL cavities have several distinctive features that enable making lasers with a high brightness, resulting from a combination of high efficiency and good beam quality, and also offer a superior flexibility to monitor the laser spectrum. In this talk I will highlight a few recent results on external-cavity organic lasers and reveal their potential through the example of a single mode organic laser device with an ultranarrow linewidth (< pm) corresponding to coherence lengths of several meters under diode pumping (typically 2-3 orders of magnitude longer than the state-of-the-art). From the material point of view, I will also show how ink-jet printing can be successfully used in vertical external-cavity organic lasers to make thick and optical-quality films that have the potential to be easily produced with a high throughput.

  10. Coupled External Cavity Photonic Crystal Enhanced Fluorescence

    PubMed Central

    Pokhriyal, Anusha; Lu, Meng; Ge, Chun; Cunningham, Brian T.

    2016-01-01

    We report a fundamentally new approach to enhance fluorescence in which surface adsorbed fluorophore-tagged biomolecules are excited on a photonic crystal surface that functions as a narrow bandwidth and tunable mirror of an external cavity laser. This scheme leads to ~10× increase in the electromagnetic enhancement factor compared to ordinary photonic crystal enhanced fluorescence. In our experiments, the cavity automatically tunes its lasing wavelength to the resonance wavelength of the photonic crystal, ensuring optimal on-resonance coupling even in the presence of variable device parameters and variations in the density of surface-adsorbed capture molecules. We achieve ~105× improvement in the limit of detection of a fluorophore-tagged protein compared to its detection on an unpatterned glass substrate. The enhanced fluorescence signal and easy optical alignment make cavity-coupled photonic crystals a viable approach for further reducing detection limits of optically-excited light emitters that are used in biological assays. PMID:23129575

  11. Coupled external cavity photonic crystal enhanced fluorescence.

    PubMed

    Pokhriyal, Anusha; Lu, Meng; Ge, Chun; Cunningham, Brian T

    2014-05-01

    We report a fundamentally new approach to enhance fluorescence in which surface adsorbed fluorophore-tagged biomolecules are excited on a photonic crystal surface that functions as a narrow bandwidth and tunable mirror of an external cavity laser. This scheme leads to ∼10× increase in the electromagnetic enhancement factor compared to ordinary photonic crystal enhanced fluorescence. In our experiments, the cavity automatically tunes its lasing wavelength to the resonance wavelength of the photonic crystal, ensuring optimal on-resonance coupling even in the presence of variable device parameters and variations in the density of surface-adsorbed capture molecules. We achieve ∼10(5) × improvement in the limit of detection of a fluorophore-tagged protein compared to its detection on an unpatterned glass substrate. The enhanced fluorescence signal and easy optical alignment make cavity-coupled photonic crystals a viable approach for further reducing detection limits of optically-excited light emitters that are used in biological assays.

  12. Ultralow noise miniature external cavity semiconductor laser

    PubMed Central

    Liang, W.; Ilchenko, V. S.; Eliyahu, D.; Savchenkov, A. A.; Matsko, A. B.; Seidel, D.; Maleki, L.

    2015-01-01

    Advanced applications in optical metrology demand improved lasers with high spectral purity, in form factors that are small and insensitive to environmental perturbations. While laboratory-scale lasers with extraordinarily high stability and low noise have been reported, all-integrated chip-scale devices with sub-100 Hz linewidth have not been previously demonstrated. Lasers integrated with optical microresonators as external cavities have the potential for substantial reduction of noise. However, stability and spectral purity improvements of these lasers have only been validated with rack-mounted support equipment, assembled with fibre lasers to marginally improve their noise performance. In this work we report on a realization of a heterogeneously integrated, chip-scale semiconductor laser featuring 30-Hz integral linewidth as well as sub-Hz instantaneous linewidth. PMID:26104321

  13. Gain chip design, power scaling and intra-cavity frequency doubling with LBO of optically pumped red-emitting AlGaInP-VECSELs

    NASA Astrophysics Data System (ADS)

    Kahle, Hermann; Mateo, Cherry M. N.; Brauch, Uwe; Bek, Roman; Schwarzbäck, Thomas; Jetter, Michael; Graf, Thomas; Michler, Peter

    2016-03-01

    The wide range of applications in biophotonics, television or projectors, spectroscopy and lithography made the optically-pumped semiconductor (OPS) vertical external cavity surface-emitting lasers (VECSELs) an important category of power scalable lasers. The possibility of bandgap engineering, inserting frequency selective and converting elements into the open laser cavity and laser emission in the fundamental Gaussian mode leads to ongoing growth of the area of applications for tuneable laser sources. We present an AlGaInP-VECSEL system with a multi quantum well structure consisting of compressively strained GaInP quantum wells in an AlxGa1-xInP separate confinement heterostructure with an emission wavelength around 665 nm. The VECSEL chip with its n-λ cavity is pumped by a 532nm Nd:YAG laser under an angle to the normal incidence of 50°. In comparison, a gain chip design for high absorption values at pump wavelengths around 640nm with the use of quantum dot layers as active material is also presented. Frequency doubling is now realized with an antireflection coated lithium borate crystal, while a birefringent filter, placed inside the laser cavity under Brewster's angle, is used for frequency tuning. Further, power-scaling methods like in-well pumping as well as embedding the active region of a VECSEL between two transparent ic heaspreaders are under investigation.

  14. Surface-emitting laser logic

    SciTech Connect

    Olbright, G.R.; Bryan, R.P.; Brennan, T.M.; Lear, K.; Poirier, G.E.; Fu, W.S. ); Jewell, J.L.; Lee, Y.H. )

    1990-10-31

    We describe a new class of optical logic devices which consist of integrated phototransistors and surface-emitting lasers. The devices function as optical neurons having high gain and, as arrays, are ideal for neural networks, parallel optical signal processing and optical computing applications. 3 refs., 3 figs.

  15. Optical Pumping of Molecular Gases

    DTIC Science & Technology

    1976-04-01

    in Hg, excimer system. IV. OPTICALLY PUMPED Na Ř The details of our optical pumping studies of Na2 are presented in Appendix I. The study showed that...inversitot In IM -Second set of linesn have. tentatively been Identified ats D asid A btuu~t-sa A-band tratsitiwts termiuiatitig, oilt*n 3,4,5 for J0 TO HELIUM

  16. Vertical Cavity Surface Emitting Laser sources for gas detection

    NASA Astrophysics Data System (ADS)

    Cerutti, L.; Garnache, A.; Ouvrard, A.; Garcia, M.; Genty, F.

    2005-03-01

    The molecular beam epitaxy growth conditions of a GaInAsSb/AlGaAsSb multi-quantum wells stack have been successfully optimised. This included minimising the full-width at half-maximum of the high resolution X-ray diffraction satellites and maximising the photoluminescence peak intensity collected at room temperature. Then, the optimised gain structures were successfully inserted in a) a microcavity and b) an external-cavity Vertical Cavity Surface Emitting Laser. In both cases, room temperature laser operation near 2.3 µm in the continuous wave regime, with a circular single transverse mode output beam, was demonstrated. An output power larger than 1 mW at room temperature was measured.

  17. Frequency stabilization of an external cavity diode laser: countermeasures against atmospheric temperature variations

    NASA Astrophysics Data System (ADS)

    Minabe, Yuta; Doi, Kohei; Sato, Takashi; Maruyama, Takeo; Ohkawa, Masashi; Tsubokawa, Tsuneya

    2008-02-01

    External cavity diode lasers (ECDL) are presently experiencing a surge in popularity, as laser light-sources for advanced optical measurement systems. While these devices normally require external optical-output controls, we simplified the setup, a bit, by adding a second external cavity. This technique boasts the added advantage of having a narrower oscillation-linewidth than would be achievable, using a single optical feedback. Because drive-current and atmospheric temperature directly impact the ECDL systems' oscillation frequency, during frequency stability checks, it was necessary, in this instance, to construct a slightly smaller ECDL system, which we mounted on a Super-Invar board, to minimize the influence of thermal expansion. Taking these and other aggressive and timely measures to prevent atmospheric temperature-related changes allowed us to achieve an improvement in oscillation-frequency stability, i.e., to obtain the square root of Allan variance σ =2×10 -10, at averaging time τ =10 -1. We introduced a vertical-cavity surface-emitting laser (VCSEL) to the setup, for the simple reason that its frequency is far less susceptible to changes in temperature, than other lasers of its type. And, because VCSELs are widely available, and the ECDL systems that use them improve frequency stability, we replaced the Fabry-Perot semiconductor laser with a VCSEL.

  18. Experimental evidence of single round-trip oscillation in polarization self-modulated vertical-cavity surface emitting lasers

    SciTech Connect

    Ropars, G.; Langot, P.; Brunel, M.; Vallet, M.; Bretenaker, F.; Le Floch, A.; Choquette, K.D.

    1997-05-01

    The polarizations and frequencies of the two eigenstates of a vertical cavity surface emitting laser with an external cavity containing a quarter-wave plate are theoretically and experimentally analyzed. It is shown that the polarizations of these eigenstates are fixed by the neutral axes of the quarter-wave plate. The optical pulses at a frequency equal to a half of the free spectral range of the external cavity, observed through a linear polarizer, are due to beats between the two eigenstates. All these features show that such polarization self-modulated lasers oscillate in a single round trip. {copyright} {ital 1997 American Institute of Physics.}

  19. Extraction of Semiconductor Microchip Differential Gain by Use of Optically Pumped Semiconductor Laser (POSTPRINT)

    DTIC Science & Technology

    2009-09-01

    2009 American Institute of Physics. doi:10.1063/1.3222899 In recent years, the vertical external cavity surface emit- ting laser VECSEL 1–4 has...received considerable attention. In the past decade, VECSELs have been investigated for their high power, high efficiency, ability to operate in con... VECSELs , indicating potential uses in low-frequency rf sources.5 Direct source applications most often necessitate digital or analog modulation, e.g

  20. Optically Pumped Cesium-Beam Frequency Standard for GPS-III

    DTIC Science & Technology

    2001-11-01

    these data was a commercial external-cavity diode laser ( ECDL ). We find that, at cesium oven temperatures consistent with a 10-year lifetime limited... ECDL ), Distributed Bragg Reflector (DBR) lasers, Vertical Cavity Surface Emitting Lasers (VCSEL), and conventional cleaved-facet diode lasers. In...Typically, we find that conventional and DBR-type lasers are capable of supporting (S / N)G up to about 10,000 and commercial ECDL lasers support up to (S

  1. Discrete Wavelength-Locked External Cavity Laser

    NASA Technical Reports Server (NTRS)

    Pilgrim, Jeffrey S.; Silver, Joel A.

    2004-01-01

    A prototype improved external cavity laser (ECL) was demonstrated in the second phase of a continuing effort to develop wavelength-agile lasers for fiber-optic communications and trace-gas-sensing applications. This laser is designed to offer next-generation performance for incorporation into fiber-optic networks. By eliminating several optical components and simplifying others used in prior designs, the design of this laser reduces costs, making lasers of this type very competitive in a price-sensitive market. Diode lasers have become enabling devices for fiber optic networks because of their cost, compactness, and spectral properties. ECLs built around diode laser gain elements further enhance capabilities by virtue of their excellent spectral properties with significantly increased (relative to prior lasers) wavelength tuning ranges. It is essential to exploit the increased spectral coverage of ECLs while simultaneously insuring that they operate only at precisely defined communication channels (wavelengths). Heretofore, this requirement has typically been satisfied through incorporation of add-in optical components that lock the ECL output wavelengths to these specific channels. Such add-in components contribute substantially to the costs of ECL lasers to be used as sources for optical communication networks. Furthermore, the optical alignment of these components, needed to attain the required wavelength precision, is a non-trivial task and can contribute substantially to production costs. The design of the present improved ECL differs significantly from the designs of prior ECLs. The present design relies on inherent features of components already included within an ECL, with slight modifications so that these components perform their normal functions while simultaneously effecting locking to the required discrete wavelengths. Hence, add-in optical components and the associated cost of alignment can be eliminated. The figure shows the locking feedback signal

  2. Silicon reflectors for external cavity lasers based on ring resonators

    NASA Astrophysics Data System (ADS)

    Wang, Chao; Li, Xia; Jin, Hao; Yu, Hui; Yang, Jianyi; Jiang, Xiaoqing

    2017-01-01

    We propose and experimentally investigate types of silicon ring reflectors on Silicon-On-Insulator (SOI) platform. These reflectors are used for realizing the silicon hybrid external cavity lasers. A suspended edge coupler is used to connect the reflective semiconductor optical amplifier (RSOA) chip and the reflectors. The properties of the reflectors and the hybrid external cavity lasers with these reflectors are illustrated. The experimental results show that all of those reflectors have a high reflectivity and the highest reflectivity can up to be 95%. The lowest insertion loss can be as low as 0.4 dB. The output power of the hybrid external cavity lasers with these reflectors can reach mW magnitude and the highest output power is 6.1 mW. Over 30 dB side mode suppression ratio is obtained.

  3. Circular polarization emission from an external cavity diode laser

    NASA Astrophysics Data System (ADS)

    Zhang, Fan; Xu, Jian; Lakhtakia, Akhlesh; Zhu, Ting; Pursel, Sean M.; Horn, Mark W.

    2008-03-01

    An external cavity diode laser (ECDL) containing a chiral sculptured-thin-film (STF) mirror for very pure circularly polarized (CP) emission was fabricated and its single-mode, left-handed CP lasing performance was observed. The extinction ratio of the CP output was found to increase rapidly near the threshold of the injection current for the laser diode. The Jones-matrix representation of a chiral STF mirror was used to calculate the eigenstates in the external cavity of the ECDL with the transfer matrix method, the results suggesting that the only resonant mode in the external cavity of the laser is CP with the same handedness as the structural handedness of the chiral STF mirror.

  4. Optical pumping and xenon NMR

    SciTech Connect

    Raftery, M. Daniel

    1991-11-01

    Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping 129Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to high magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the 131Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen.

  5. Optical pumping and xenon NMR

    SciTech Connect

    Raftery, M.D.

    1991-11-01

    Nuclear Magnetic Resonance (NMR) spectroscopy of xenon has become an important tool for investigating a wide variety of materials, especially those with high surface area. The sensitivity of its chemical shift to environment, and its chemical inertness and adsorption properties make xenon a particularly useful NMR probe. This work discusses the application of optical pumping to enhance the sensitivity of xenon NMR experiments, thereby allowing them to be used in the study of systems with lower surface area. A novel method of optically-pumping [sup 129]Xe in low magnetic field below an NMR spectrometer and subsequent transfer of the gas to high magnetic field is described. NMR studies of the highly polarized gas adsorbed onto powdered samples with low to moderate surface areas are now possible. For instance, NMR studies of optically-pumped xenon adsorbed onto polyacrylic acid show that xenon has a large interaction with the surface. By modeling the low temperature data in terms of a sticking probability and the gas phase xenon-xenon interaction, the diffusion coefficient for xenon at the surface of the polymer is determined. The sensitivity enhancement afforded by optical pumping also allows the NMR observation of xenon thin films frozen onto the inner surfaces of different sample cells. The geometry of the thin films results in interesting line shapes that are due to the bulk magnetic susceptibility of xenon. Experiments are also described that combine optical pumping with optical detection for high sensitivity in low magnetic field to observe the quadrupoler evolution of 131 Xe spins at the surface of the pumping cells. In cells with macroscopic asymmetry, a residual quadrupolar interaction causes a splitting in the [sup 131]Xe NMR frequencies in bare Pyrex glass cells and cells with added hydrogen.

  6. Active Wavelength Control of an External Cavity Quantum Cascade Laser

    PubMed Central

    Tsai, Tracy; Wysocki, Gerard

    2012-01-01

    We present an active wavelength control system for grating-based external cavity lasers that increases the accuracy of predicting the lasing wavelength based on the grating equation and significantly improves scan-to-scan wavelength/frequency repeatability. The ultimate 3σ precision of a frequency scan is determined by the scan-to-scan repeatability of 0.042 cm−1. Since this control method can be applied to any external cavity laser with little to no modification, such a precision provides an excellent opportunity for spectroscopic applications that target molecular absorption lines at standard atmospheric conditions. PMID:23483850

  7. Mirrorless Lasing in Optically Pumped Rubidium Vapor

    DTIC Science & Technology

    2013-03-01

    MIRRORLESS LASING IN OPTICALLY PUMPED RUBIDIUM VAPOR THESIS Ryan M. Richards AFIT-ENP...MIRRORLESS LASING IN OPTICALLY PUMPED RUBIDIUM VAPOR THESIS Presented to the Faculty Department of Physics Graduate School of...RELEASE; DISTRIBUTION IS UNLIMITED. v AFIT-ENP-13-M-41 MIRRORLESS LASING IN OPTICALLY PUMPED RUBIDIUM VAPOR Ryan M. Richards

  8. High Power 7-GHz Bandwidth External-Cavity Diode Laser Array and Its Use in Optically Pumping Singlet Delta Oxygen

    DTIC Science & Technology

    2006-10-11

    array,” Opt. Lett. 19, 1741 (1994). 2. Stuart MacCormack, Jack Feinberg, and M. H. Garrett , “Injection locking a laser-diode array with a phase...generate O2( 1∆) molecules, frequently called Singlet Delta Oxygen (SDO) molecules. High-power chemical oxygen-iodine lasers ( COIL ) use energy...45 A, thermal roll -over effect starts and output power drops due to high temperature (~30oC) of the DLA. The green data are the DLA’s free-running

  9. Single orbital angular mode emission from externally feed-backed vertical cavity surface emitting laser

    NASA Astrophysics Data System (ADS)

    Toda, Y.; Moriya, A.; Yamane, K.; Morita, R.; Shigematsu, K.; Awaji, Y.

    2017-09-01

    The single orbital angular momentum mode emission from a commercially available broad-area vertical cavity surface emitting laser (VCSEL) is realized with an optical feedback technique using a spatial light modulator, where a computer generated hologram (CGH) is optimized by taking into account the mode properties of the external cavity VCSEL. The flexibility with which the chirality of the orbital angular momentum mode can be selected is also demonstrated simply by changing the chirality of the CGH. The technique is very simple and easily applicable to other VCSELs without processing.

  10. Wavelength-Agile External-Cavity Diode Laser for DWDM

    NASA Technical Reports Server (NTRS)

    Pilgrim, Jeffrey S.; Bomse, David S.

    2006-01-01

    A prototype external-cavity diode laser (ECDL) has been developed for communication systems utilizing dense wavelength- division multiplexing (DWDM). This ECDL is an updated version of the ECDL reported in Wavelength-Agile External- Cavity Diode Laser (LEW-17090), NASA Tech Briefs, Vol. 25, No. 11 (November 2001), page 14a. To recapitulate: The wavelength-agile ECDL combines the stability of an external-cavity laser with the wavelength agility of a diode laser. Wavelength is modulated by modulating the injection current of the diode-laser gain element. The external cavity is a Littman-Metcalf resonator, in which the zeroth-order output from a diffraction grating is used as the laser output and the first-order-diffracted light is retro-reflected by a cavity feedback mirror, which establishes one end of the resonator. The other end of the resonator is the output surface of a Fabry-Perot resonator that constitutes the diode-laser gain element. Wavelength is selected by choosing the angle of the diffracted return beam, as determined by position of the feedback mirror. The present wavelength-agile ECDL is distinguished by design details that enable coverage of all 60 channels, separated by 100-GHz frequency intervals, that are specified in DWDM standards.

  11. Circular polarization emission from an external cavity diode laser

    NASA Astrophysics Data System (ADS)

    Xu, Jian; Zhang, Fan; Lakhtakia, Akhlesh; Pursel, Sean M.; Horn, Mark W.

    2008-08-01

    We construct an external cavity diode laser (ECDL) comprising structurally left-handed chiral sculptured-thin-film (STF) mirrors for pure circular-polarized (CP) emission, and observed single mode, left-handed CP lasing performance. The extinction ratio of CP output was found to increase rapidly near the threshold of the injection-current for the laser diodes.

  12. Vertical cavity surface emitting laser emitting at 1.56 microns with AlGaAsSb/AlAsSb distributed Bragg reflectors

    SciTech Connect

    Blum, O.; Klem, J.F.; Lear, K.L.; Vawter, G.A.; Kurtz, S.R.

    1998-07-01

    The authors report 77K operation of an optically pumped vertical cavity surface emitting laser with an Sb-based cavity. The structure consists of 15 and 20 pair AlGaAsSb/AlAsSb top and bottom reflectors and a bulk InGaAs active region.

  13. Optically pumped polarized ion sources

    SciTech Connect

    Anderson, L.W.

    1995-04-01

    Polarized negative hydrogen ions are produced in an optically pumped polarized ion source (OPPIS) as follows. A proton beam is extracted from an ECR ion source, accelerated to an energy of a few kilovolts, and focused into a parallel beam. The proton beam is passed through an optically pumped electron spin polarized alkali vapor target in a large magnetic field where the proton beam is partially neutralized by the pick-up of a polarized electron. The optically pumped alkali vapor target must be in a magnetic field large enough to decouple L and S in the n=2 level of atomic hydrogen so that the radiative decay to the ground level does not result in the loss of electron spin polarization. The large magnetic field also helps avoid radiation trapping limitations on the alkali density. The resulting fast atomic hydrogen beam passes through zero field where Sona transitions convert the electron spin polarization into nuclear spin polarization. The beam then is partially converted into polarized negative hydrogen ions in a sodium vapor target. At the present time the best dc OPPIS (at TRIUMF) produces 120 {mu}A with a polarization of 0.8. The best pulsed OPPIS (at INR in Moscow) produces 400 {mu}A. The use of OPPIS with deuterium has been pioneered at KEK in Japan. There is current research at TRIUMF on the possibility of using multiple spin/charge exchange collisions to increase the available current into the mA range, and there is current research at Osaka in the use of the technique with heavier ions such as helium.

  14. Pulsed optically pumped frequency standard

    SciTech Connect

    Godone, Aldo; Micalizio, Salvatore; Levi, Filippo

    2004-08-01

    We reconsider the idea of a pulsed optically pumped frequency standard conceived in the early 1960s to eliminate the light-shift effect. The development of semiconductor lasers and of pulsed electronic techniques for atomic fountains and new theoretical findings allow an implementation of this idea which may lead to a frequency standard whose frequency stability is limited only by the thermal noise in the short term and by the temperature drift in the long term. We shall also show both theoretically and experimentally the possibility of doubling the atomic quality factor with respect to the classical Ramsey technique approach.

  15. Pulsed Optically Pumped Rb clock

    NASA Astrophysics Data System (ADS)

    Micalizio, S.; Levi, F.; Godone, A.; Calosso, C. E.; François, B.; Boudot, R.; Affolderbach, C.; Kang, S.; Gharavipour, M.; Gruet, F.; Mileti, G.

    2016-06-01

    INRIM demonstrated a Rb vapour cell clock based on pulsed optical pumping (POP) with unprecedented frequency stability performances, both in the short and in the medium-long term period. In the frame of a EMRP project, we are developing a new clock based on the same POP principle but adopting solutions aimed at reducing the noise sources affecting the INRIM clock. At the same time, concerning possible technological applications, particular care are devoted in the project to reduce the size and the weight of the clock, still keeping the excellent stability of the INRIM clock. The paper resumes the main results of this activity.

  16. Optically pumped isotopic ammonia laser system

    DOEpatents

    Buchwald, Melvin I.; Jones, Claude R.; Nelson, Leonard Y.

    1982-01-01

    An optically pumped isotopic ammonia laser system which is capable of producing a plurality of frequencies in the middle infrared spectral region. Two optical pumping mechanisms are disclosed, i.e., pumping on R(J) and lasing on P(J) in response to enhancement of rotational cascade lasing including stimulated Raman effects, and, pumping on R(J) and lasing on P(J+2). The disclosed apparatus for optical pumping include a hole coupled cavity and a grating coupled cavity.

  17. Surface-emitting red, green, and blue colloidal quantum dot distributed feedback lasers.

    PubMed

    Roh, Kwangdong; Dang, Cuong; Lee, Joonhee; Chen, Songtao; Steckel, Jonathan S; Coe-Sullivan, Seth; Nurmikko, Arto

    2014-07-28

    We demonstrate surface emitting distributed feedback (DFB) lasers across the red, green, and blue from densely packed colloidal quantum dot (CQD) films. The solid CQD films were deposited on periodic grating patterns to enable 2nd-order DFB lasing action at mere 120, 280, and 330 μJ/cm2 of optical pumping energy densities for red, green, and blue DFB lasers, respectively. The lasers operated in single mode operation with less than 1 nm of full-width-half-maximum. We measured far-field patterns showing high degree of spatial beam coherence. Specifically, by taking advantage of single exciton optical gain regime from our engineered CQDs, we can significantly suppress the Auger recombination to reduce lasing threshold and achieve quasi-steady state, optically pumped operation.

  18. CVD-diamond external cavity Raman laser at 573 nm.

    PubMed

    Mildren, Richard P; Butler, James E; Rabeau, James R

    2008-11-10

    Recent progress in diamond growth via chemical vapor deposition (CVD) has enabled the manufacture of single crystal samples of sufficient size and quality for realizing Raman laser devices. Here we report an external cavity CVD-diamond Raman laser pumped by a Q-switched 532 nm laser. In the investigated configuration, the dominant output coupling was by reflection loss at the diamond's uncoated Brewster angle facets caused by the crystal's inherent birefringence. Output pulses of wavelength 573 nm with a combined energy of 0.3 mJ were obtained with a slope efficiency of conversion of up to 22%.

  19. External cavity beam combining of 21 semiconductor lasers using SPGD.

    PubMed

    Montoya, Juan; Augst, Steven J; Creedon, Kevin; Kansky, Jan; Fan, Tso Yee; Sanchez-Rubio, Antonio

    2012-04-10

    Active coherent beam combining of laser oscillators is an attractive way to achieve high output power in a diffraction limited beam. Here we describe an active beam combining system used to coherently combine 21 semiconductor laser elements with an 81% beam combining efficiency in an external cavity configuration compared with an upper limit of 90% efficiency in the particular configuration of the experiment. Our beam combining system utilizes a stochastic parallel gradient descent (SPGD) algorithm for active phase control. This work demonstrates that active beam combining is not subject to the scaling limits imposed on passive-phasing systems.

  20. External cavity diode laser with very-low frequency drift

    NASA Astrophysics Data System (ADS)

    Takamizawa, Akifumi; Yanagimachi, Shinya; Ikegami, Takeshi

    2016-03-01

    An external cavity diode laser with significant mechanical robustness was installed in a housing that was sealed from outside for eliminating variations in the refractive index of air. Using the feedback signal for a frequency lock, it was found that the variation in the laser frequency under free running was suppressed to 275 MHz over one month and depended on the room temperature. Moreover, the upper limit of the linear frequency drift rate was evaluated as intrinsically 40 Hz/s. The frequency lock is expected to be sustainable for more than 110 days with temperature-controlled housing.

  1. Array mode selection utilizing an external cavity configuration

    SciTech Connect

    Yaeli, J.; Streifer, W.; Scifres, D.R.; Cross, P.S.; Thornton, R.L.; Burnham, R.D.

    1985-07-15

    We report operation of a ten-stripe, gain-guided, phase-locked diode laser in an external cavity configuration. The laser radiates in a single narrow (1/sup 0/) lobe. Such lasers generally lase in the highest order array mode, L = 10, which radiates in a twin-lobe far-field pattern. With one antireflection-coated facet and a slit spatial filter, the laser has been operated in the L = 1, 2, 3 or 10 array modes. A theoretical explanation of the spatial filter function is included.

  2. An external cavity diode laser using a volume holographic grating

    NASA Astrophysics Data System (ADS)

    Chuang, Ho-Chiao; Chang, Chang-Ray; Chen, Chun-Chia; Chang, Ming-Shien

    2012-10-01

    This study presents an external cavity diode laser (ECDL) system, utilizing a volume holographic grating (VHG) and a microfabricated silicon flexure as the VHG holder. The laser design is aimed for easy assembly, controllability, and better stability of the laser cavity. The laser frequency was stabilized to a D2 transition of rubidium at 780.247 nm, with a mode-hop-free tuning range of 16 GHz and 9.6 GHz with and without feed-forward on the diode injection current. The measured linewidth was 850 kHz in 500 s, qualified for laser cooling experiments.

  3. Rubidium Spectroscopy with an External Cavity Diode Laser

    NASA Astrophysics Data System (ADS)

    Burgess, Charity; Smith, R. Seth

    2014-03-01

    A homebuilt external cavity diode laser (ECDL) was used to provide a very narrow range of laser wavelengths near 780 nm in order to study the structure of rubidium (Rb). The absorption spectrum of Rb was measured. This spectrum was subject to Doppler-broadening of the spectral lines. A technique known as Saturated Absorption Spectroscopy was employed to eliminate the effects of Doppler-broadening and to obtain a high resolution spectrum for Rubidium. The setup, operation, and performance of this system will be described. Research made possible by a REAL grant from Francis Marion University.

  4. Visible Vertical Cavity Surface Emitting Lasers

    DTIC Science & Technology

    1993-01-01

    Visible VCSEL ................ 103 3.6 Analysis of Results ............................... 113 3.7 Conclusions .................................. 117 4...Stacks ........... 41 2.4 Estimated Mobility and Conductivity of Selected Epitaxial Layers ....... 58 2.5 Summary of the DBR Voltage Drop Analysis ...wavelength both for the optically pumped hybrid visible VCSEL ............... 114 3.15 Qualitative analysis of the gain versus lasing wavelength results for

  5. Enhancement of {sup 129}Xe polarization by off-resonant spin exchange optical pumping

    SciTech Connect

    Parnell, S. R.; Deppe, M. H.; Parra-Robles, J.; Wild, J. M.

    2010-09-15

    A high power narrow line width (38 W, 0.09 nm full width at half maximum) external cavity diode laser is investigated for rubidium spin exchange optical pumping of {sup 129}Xe. This tunable photon source has a constant line width, independent of operating power or wavelength within a 1 nm tuning range. When using this laser, an increase in the {sup 129}Xe nuclear polarization is observed when optically pumping at a lower wavelength than the measured Rb electron D{sub 1} absorption. The exact detuning from D{sub 1} for the highest polarization is dependent upon the gas density. Furthermore, at high power and/or high Rb density, a reduction in the polarization occurs at the optimum wavelength as previously reported in spin exchange optical pumping studies of {sup 3}He which is consistent with high absorption close to the cell front face. These results are encouraging for moderate high throughput polarization of {sup 129}Xe in the midpressure range of (0.5-2.0 amagat).

  6. Optically Pumped Carbon Monoxide Cascade Laser

    DTIC Science & Technology

    2005-07-01

    absorption problems it poses. Instead, a 2.3 gtm GaSb diode laser could be used as a 1st overtone optically pumped source. The absorption cross section at...OPTICALLY PUMPED CARBON MONOXIDE CASCADE LASER BY NICHOLAS W. SAWRUK B.S., PHYSICS, US AIR FORCE ACADEMY, 2001 B.S., MATHEMATICS, US AIR FORCE...SUBTITLE 5. FUNDING NUMBERS OPTICALLY PUMPED CARBON MONOXIDE CASCADE LASER 6. AUTHOR(S) 1ST LT SAWRUK NICHOLAS W 7. PERFORMING ORGANIZATION NAME(S) AND

  7. External cavity diode laser setup with two interference filters

    NASA Astrophysics Data System (ADS)

    Martin, Alexander; Baus, Patrick; Birkl, Gerhard

    2016-12-01

    We present an external cavity diode laser setup using two identical, commercially available interference filters operated in the blue wavelength range around 450 nm. The combination of the two filters decreases the transmission width, while increasing the edge steepness without a significant reduction in peak transmittance. Due to the broad spectral transmission of these interference filters compared to the internal mode spacing of blue laser diodes, an additional locking scheme, based on Hänsch-Couillaud locking to a cavity, has been added to improve the stability. The laser is stabilized to a line in the tellurium spectrum via saturation spectroscopy, and single-frequency operation for a duration of two days is demonstrated by monitoring the error signal of the lock and the piezo drive compensating the length change of the external resonator due to air pressure variations. Additionally, transmission curves of the filters and the spectra of a sample of diodes are given.

  8. High-power external cavity CW red laser diode

    NASA Astrophysics Data System (ADS)

    Song, Hong Joo; Lee, Jun Ho; Park, Jiyeon; Park, Jong Hwan; Na, Hong Man; Park, Jung Ho

    2015-03-01

    An front facet-low reflection coated broad-area laser(BAL) diode with an emitter size of 50 μm x 1 μm and a chip length of 2000 μm is operated in the external cavity diode laser(ECDL). For wavelength stabilization and narrow spectral width, the diffraction grating is used in a Littrow configuration. At an injection current of 1.5 A, a output power of 0.65 W with a slop efficiency of 0.85 A/W, which is comparable to those of a solitary BAL diode, could be achieved with a spectral width of 120pm which is about 77 % narrower as compared to a solitary BAL diode. The peak wavelength stability below 10 pm was obtained in the wide range of output power up to 0.65 W.

  9. Breath analysis using external cavity diode lasers: a review

    NASA Astrophysics Data System (ADS)

    Bayrakli, Ismail

    2017-04-01

    Most techniques that are used for diagnosis and therapy of diseases are invasive. Reliable noninvasive methods are always needed for the comfort of patients. Owing to its noninvasiveness, ease of use, and easy repeatability, exhaled breath analysis is a very good candidate for this purpose. Breath analysis can be performed using different techniques, such as gas chromatography mass spectrometry (MS), proton transfer reaction-MS, and selected ion flow tube-MS. However, these devices are bulky and require complicated procedures for sample collection and preconcentration. Therefore, these are not practical for routine applications in hospitals. Laser-based techniques with small size, robustness, low cost, low response time, accuracy, precision, high sensitivity, selectivity, low detection limit, real-time, and point-of-care detection have a great potential for routine use in hospitals. In this review paper, the recent advances in the fields of external cavity lasers and breath analysis for detection of diseases are presented.

  10. Tunable external cavity laser employing uncooled superluminescent diode.

    PubMed

    Oh, Su Hwan; Kim, Ki Soo; Ju, Jung Jin; Kim, Min-Su; Yoon, Ki-Hong; Oh, Dae Kon; Noh, Young-Ouk; Lee, Hyung-Jong

    2009-06-08

    We have fabricated a tunable external cavity laser (T-ECL) based on a superluminescent diode and a polymeric waveguide Bragg reflector, providing a cost-effective solution for wavelength division multiplexing-passive optical network (WDM-PON) systems. The wavelength of the T-ECL is tuned through 100 GHz-spacing 16 channels by the thermo-optic tuning of the refractive index of the polymer waveguide at a low input power of 70 mW. The maximum output power and the slope efficiency of the uncooled diode at 20 (75) degrees C are 8.83 (3.80) mW and 0.107 (0.061) W/A, respectively. The T-ECL operated successfully in the direct modulation for 1.25 Gbit/s transmissions over 20 km.

  11. Breath analysis using external cavity diode lasers: a review.

    PubMed

    Bayrakli, Ismail

    2017-04-01

    Most techniques that are used for diagnosis and therapy of diseases are invasive. Reliable noninvasive methods are always needed for the comfort of patients. Owing to its noninvasiveness, ease of use, and easy repeatability, exhaled breath analysis is a very good candidate for this purpose. Breath analysis can be performed using different techniques, such as gas chromatography mass spectrometry (MS), proton transfer reaction-MS, and selected ion flow tube-MS. However, these devices are bulky and require complicated procedures for sample collection and preconcentration. Therefore, these are not practical for routine applications in hospitals. Laser-based techniques with small size, robustness, low cost, low response time, accuracy, precision, high sensitivity, selectivity, low detection limit, real-time, and point-of-care detection have a great potential for routine use in hospitals. In this review paper, the recent advances in the fields of external cavity lasers and breath analysis for detection of diseases are presented.

  12. Fast wavelength tuning techniques for external cavity lasers

    DOEpatents

    Wysocki, Gerard [Princeton, NJ; Tittel, Frank K [Houston, TX

    2011-01-11

    An apparatus comprising a laser source configured to emit a light beam along a first path, an optical beam steering component configured to steer the light beam from the first path to a second path at an angle to the first path, and a diffraction grating configured to reflect back at least a portion of the light beam along the second path, wherein the angle determines an external cavity length. Included is an apparatus comprising a laser source configured to emit a light beam along a first path, a beam steering component configured to redirect the light beam to a second path at an angle to the first path, wherein the optical beam steering component is configured to change the angle at a rate of at least about one Kilohertz, and a diffraction grating configured to reflect back at least a portion of the light beam along the second path.

  13. Resonator modes and mode dynamics for an external cavity-coupled laser array

    NASA Astrophysics Data System (ADS)

    Nair, Niketh; Bochove, Erik J.; Aceves, Alejandro B.; Zunoubi, Mohammad R.; Braiman, Yehuda

    2015-03-01

    Employing a Fox-Li approach, we derived the cold-cavity mode structure and a coupled mode theory for a phased array of N single-transverse-mode active waveguides with feedback from an external cavity. We applied the analysis to a system with arbitrary laser lengths, external cavity design and coupling strengths to the external cavity. The entire system was treated as a single resonator. The effect of the external cavity was modeled by a set of boundary conditions expressed by an N-by-N frequency-dependent matrix relation between incident and reflected fields at the interface with the external cavity. The coupled mode theory can be adapted to various types of gain media and internal and external cavity designs.

  14. Optically pumped VECSELs: review of technology and progress

    NASA Astrophysics Data System (ADS)

    Guina, M.; Rantamäki, A.; Härkönen, A.

    2017-09-01

    Vertical-external-cavity surface-emitting lasers (VECSELs) are the most versatile laser sources, combining unique features such as wide spectral coverage, ultrashort pulse operation, low noise properties, high output power, high brightness and compact form-factor. This paper reviews the recent technological developments of VECSELs in connection with the new milestones that continue to pave the way towards their use in numerous applications. Significant attention is devoted to the fabrication of VECSEL gain mirrors in challenging wavelength regions, especially at the yellow and red wavelengths. The reviewed fabrication approaches address wafer-bonded VECSEL structures as well as the use of hybrid mirror structures. Moreover, a comprehensive summary of VECSEL characterization methods is presented; the discussion covers different stages of VECSEL development and different operation regimes, pointing out specific characterization techniques for each of them. Finally, several emerging applications are discussed, with emphasis on the unique application objectives that VECSELs render possible, for example in atom and molecular physics, dermatology and spectroscopy.

  15. The use of an external cavity with the SCA/FEL

    NASA Astrophysics Data System (ADS)

    Haar, P.; Fishman, I. M.; Smith, T. I.; Schwettman, H. A.

    1992-07-01

    We have investigated the possibility of coupling the FEL optical beam into an external cavity. The resulting buildup of optical energy in the cavity offers several advantages. First, the sensitivity of the stored energy to source instabilities makes the external cavity a powerful FEL diagnostic. The dependence of the stored energy on several important instabilities will be discussed, as will plans for actually quantifying these instabilities with the external cavity. Second, a large amount of energy can be accumulated in the external cavity. Outcoupling this energy can significantly increase the micropulse energy delivered. Three possible outcoupling schemes will be discussed: "enhanced" outcoupling, photo-activated cavity dumping, and electro-optic cavity dumping.

  16. Beam quality improvement of laser diode array by using off-axis external cavity.

    PubMed

    Zhouping, Su; Qihong, Lou; Jingxing, Dong; Jun, Zhou; Runrong, Wei

    2007-09-17

    A novel off-axis external cavity is designed for laser diode array to improve the beam quality. In this external cavity, a circle aperture with variable size is used as a spatial filter. The diameter of aperture is optimized to 1.2mm and the off-axis angle of external cavity is optimized at 2.6 deg. In the optimal case, the beam parameter product (BPP) of laser diode array is reduced to 121 mm.mrad from 1050 mm.mrad with external cavity optical efficiency of 81%.

  17. External cavity quantum cascade lasers for spectroscopic applications

    NASA Astrophysics Data System (ADS)

    Tsai, Tracy

    Mid-infrared spectroscopy is a powerful tool in monitoring trace gases for applications in atmospheric science, industrial processes, and homeland security. However, although current mid-infrared spectrometers (i.e. Fourier Transform Spectrometers or FTS) have a wide spectral range for multi-species and/or broadband molecular detection, they are too large with slow scan rates for practical use in high resolution spectroscopic applications. Quantum cascade lasers (QCLs) are compact, powerful, and efficient mid-infrared sources that can be quantum engineered with broadband gain profiles. Placed inside a diffraction grating based external cavity arrangement, they can easily provide >100 cm -1 frequency range with a spectral resolution limited by the laser linewidth (˜10-3 cm-1). Therefore, the external cavity quantum cascade laser (EC-QCL) provides both high spectral resolution and a wide frequency range. This thesis describes the study and development of EC-QCLs for spectroscopic applications. A new active wavelength method is presented to simplify the spectrometer system by allowing for reliable operation of the EC-QCL without additional wavelength diagnostic equipment. Typically, such equipment must be added to the spectrometer, because the grating equation is inaccurate in describing the EC-QCL output wavelength due to spectral misalignment of other wavelength-selective resonances in the EC-QCL. The active wavelength locking method automatically controls the EC-QCL wavelength, which improves the accuracy of the grating equation to 0.06 cm-1 and offers an ultimate 3σ precision of 0.042 cm-1. For industrial spectroscopic sensing applications in which scan rates must be on the order of kilohertz so that the turbulent gas system can be approximated as a quasi-stable one, a fast-wavelength-scanning folded EC-QCL design capable of 1 kHz scan rate is presented. Two modes of operation have been studied: 1) low resolution pulsed mode and 2) high resolution continuous

  18. Tunable high-power blue external cavity semiconductor laser

    NASA Astrophysics Data System (ADS)

    Ding, Ding; Lv, Xueqin; Chen, Xinyi; Wang, Fei; Zhang, Jiangyong; Che, Kaijun

    2017-09-01

    A commercially available high-power GaN-based blue laser diode has been operated in a simple Littrow-type external cavity (EC). Two kinds of EC configurations with the grating lines perpendicular (A configuration) and parallel (B configuration) to the p-n junction are evaluated. Good performance has been demonstrated for the EC laser with B configuration due to the better mode selection effect induced by the narrow feedback wavelength range from the grating. Under an injection current of 1100 mA, the spectral linewidth is narrowed significantly down to ∼0.1 nm from ∼1 nm (the free-running width), with a good wavelength-locking behavior and a higher than 35 dB-amplified spontaneous emission suppression ratio. Moreover, a tuning bandwidth of 3.6 nm from 443.9 nm to 447.5 nm is realized with output power of 1.24 W and EC coupling efficiency of 80% at the central wavelength. The grating-coupled blue EC laser with narrow spectral linewidth, flexible wavelength tunability, and high output power shows potential applications in atom cooling and trapping, high-resolution spectroscopy, second harmonic generation, and high-capacity holographic data storage.

  19. Tunable multiwavelength quantum dot external-cavity lasers

    NASA Astrophysics Data System (ADS)

    Pai, Chen-Hung; Lin, Gray

    2013-05-01

    The chirped multilayer quantum-dot (QD) gain media are arranged in Fourier-transform external-cavity laser (FT-ECL) configuration. Novel slit designs select 2, 3, and 4 different wavelengths that are diffracted from the grating for optical feedback. Therefore, the dual-, triple- and quadruple-wavelength ECLs are demonstrated in this study. The resulted multi-wavelength lasing emissions are achieved under injected current of 100 mA (or 1.33 kA/cm2) with signal to amplified spontaneous emission (ASE) ratio over 20 dB. Around peak-gain wavelength of 12xx-nm range, the adjacent wavelength separation is over 50 nm for dual-wavelength lasing, up to 13 nm for triple-wavelength lasing, and about 4-5 nm for quadruple-wavelength lasing emissions. To further extend the wavelength separation for dual-wavelength lasing emissions, another modified scheme with two separate external mirrors are adopted and the achieved maximum value is about 126 nm in wavelength separation or over 25 THz in frequency difference. The terahertz (THz) generation by photomixing of dual-wavelength ECLs is also discussed in this study.

  20. Modeling and cavity optimization of an external cavity semiconductor laser

    NASA Astrophysics Data System (ADS)

    Feies, Valentin I.; Montrosset, Ivo

    2004-09-01

    Semiconductor external cavity lasers (ECL) have a wide range of applications in the field of DWDM and measurement systems. One of their most important features is the continuous tuning without mode hopping in a wide wavelength range. In this paper we present a modelling approach for an ECL in Littman-Metcalf configuration carried out for optimising: 1) the laser diode position inside the cavity in order to maximize the range of continuous wavelength tuning without mode hopping and without cavity-length adjustment and 2) the choice of the detuning of the operating wavelength respect to the Bragg condition in order to minimize the four-wave mixing (FWM) effects and the effect of a non-perfect antireflection coating (ARC). A realistic example has been analyzed and therefore we considered: the wavelength dependence of the modal gain, linewidth enhancement factor and grating selectivity, as well as the modal refractive index change with carrier injection, operating wavelength and temperature. The implemented numerical tools allow also to obtain some specifications on the grating selectivity and the ARC design.

  1. Surface emitting lasers with combined output

    NASA Technical Reports Server (NTRS)

    Carlin, Donald B. (Inventor)

    1990-01-01

    Surface emitting lasers are laterally aligned and coupled together and also have their light output signals combined. This results in greater phase and frequency coherency and narrower and reduced amplitude sidelobes. Preferably, not more than two lasers are longitudinally aligned along the same axis for still greater coherency compared with adding the light output signals of more than two longitudinally aligned lasers. The lasers can be of the DH-LOC type or of the QW type.

  2. High Sensitivity Optically Pumped Quantum Magnetometer

    PubMed Central

    Tiporlini, Valentina; Alameh, Kamal

    2013-01-01

    Quantum magnetometers based on optical pumping can achieve sensitivity as high as what SQUID-based devices can attain. In this paper, we discuss the principle of operation and the optimal design of an optically pumped quantum magnetometer. The ultimate intrinsic sensitivity is calculated showing that optimal performance of the magnetometer is attained with an optical pump power of 20 μW and an operation temperature of 48°C. Results show that the ultimate intrinsic sensitivity of the quantum magnetometer that can be achieved is 327 fT/Hz1/2 over a bandwidth of 26 Hz and that this sensitivity drops to 130 pT/Hz1/2 in the presence of environmental noise. The quantum magnetometer is shown to be capable of detecting a sinusoidal magnetic field of amplitude as low as 15 pT oscillating at 25 Hz. PMID:23766716

  3. High sensitivity optically pumped quantum magnetometer.

    PubMed

    Tiporlini, Valentina; Alameh, Kamal

    2013-01-01

    Quantum magnetometers based on optical pumping can achieve sensitivity as high as what SQUID-based devices can attain. In this paper, we discuss the principle of operation and the optimal design of an optically pumped quantum magnetometer. The ultimate intrinsic sensitivity is calculated showing that optimal performance of the magnetometer is attained with an optical pump power of 20 μW and an operation temperature of 48°C. Results show that the ultimate intrinsic sensitivity of the quantum magnetometer that can be achieved is 327 fT/Hz(½) over a bandwidth of 26 Hz and that this sensitivity drops to 130 pT/Hz(½) in the presence of environmental noise. The quantum magnetometer is shown to be capable of detecting a sinusoidal magnetic field of amplitude as low as 15 pT oscillating at 25 Hz.

  4. Photon Budget in Spin Exchange Optical Pumping

    NASA Astrophysics Data System (ADS)

    Lancor, Brian; Wyllie, Robert; Walker, Thad

    2009-05-01

    Standard models of spin-exchange optical pumping that include all known collisional spin relaxation and assume excited-state nuclear spin conservation consistently under-represent the amount of optical pumping light required to produce large quantities of polarized gas. The extremely large optical depths (˜100) used in these experiments require high transparency for fully polarized alkali atoms. Should polarized atoms continue to absorb light, even at a small rate, the effects on photon usage are dramatic. We are currently investigating the frequency dependence of the circular dichroism of the Rb D1 resonance. This effect may be of particular importance for broad linewidth laser sources. In addition, we have quantitatively modeled the evolution of the Rb nuclear spin during the optical pumping process, and find that the standard assumption of nuclear spin conservation in the excited state is violated and has a significant effect on photon usage.

  5. Optical pumping production of spin polarized hydrogen

    SciTech Connect

    Knize, R.J.; Happer, W.; Cecchi, J.L.

    1984-09-01

    There has been much interest recently in the production of large quantities of spin polarized hydrogen in various fields, including controlled fusion, quantum fluids, high energy, and nuclear physics. One promising method for the development of large quantities of spin polarized hydrogen is the utilization of optical pumping with a laser. Optical pumping is a process in which photon angular momentum is converted into electron and nuclear spin. The advent of tunable CW dye lasers (approx. 1 watt) allows the production of greater than 10/sup 18/ polarized atoms/sec. We have begun a program at Princeton to investigate the physics and technology of using optical pumping to produce large quantities of spin polarized hydrogen. Initial experiments have been done in small closed glass cells. Eventually, a flowing system, open target, or polarized ion source could be constructed.

  6. Optically Pumped Carbon Monoxide Cascade Laser

    DTIC Science & Technology

    2005-06-30

    bother with the small absorption cross-sections of 2nd overtone pumping and the absorption problems it poses. Instead, a 2.3 µm GaSb diode laser ...could be used as a 1 st overtone optically pumped source. The absorption cross section at 2.3 µm is over 100 times larger. The 2.3 µm diode laser is...AFRL-DE-PS- AFRL-DE-PS- TR-2005-1093 TR-2005-1093 OPTICALLY PUMPED CARBON MONOXIDE CASCADE LASER NICHOLAS W. SAWRUK 30 June 2005 Final Report

  7. Optically pumped nuclear magnetic resonance of semiconductors.

    PubMed

    Hayes, Sophia E; Mui, Stacy; Ramaswamy, Kannan

    2008-02-07

    Optically pumped NMR (OPNMR) of direct gap and indirect gap semiconductors has been an area of active research interest, motivated by both basic science and technological perspectives. Proposals to enhance and to spatially localize nuclear polarization have stimulated interest in this area. Recent progress in OPNMR has focused on exploring the experimental parameter space in order to elucidate details of the underlying photophysics of optical pumping phenomena. The focus of this review is on recent studies of bulk samples of GaAs and InP, namely, the photon energy dependence, the magnetic field dependence, and the phase dependence of OPNMR resonances. Models for the development of nuclear polarization are discussed.

  8. Controlled switching of ultrafast circular polarization oscillations in spin-polarized vertical-cavity surface-emitting lasers

    NASA Astrophysics Data System (ADS)

    Höpfner, Henning; Lindemann, Markus; Gerhardt, Nils C.; Hofmann, Martin R.

    2014-01-01

    We demonstrate a scheme for controlled switching of polarization oscillations in spin-polarized vertical-cavity surface-emitting lasers (spin-VCSEL). Under hybrid electrical and optical pumping conditions, our VCSEL devices show polarization oscillations with frequencies far above the VCSEL's electrical modulation bandwidth. Using multiple optical pulses, we are able to excite and amplify these polarization oscillations. When specific phase and amplitude conditions for the optical excitation pulses are met, destructive interference leads to switch-off of the polarization oscillation, enabling the generation of controlled short polarization bursts.

  9. Controlled switching of ultrafast circular polarization oscillations in spin-polarized vertical-cavity surface-emitting lasers

    SciTech Connect

    Höpfner, Henning Lindemann, Markus; Gerhardt, Nils C.; Hofmann, Martin R.

    2014-01-13

    We demonstrate a scheme for controlled switching of polarization oscillations in spin-polarized vertical-cavity surface-emitting lasers (spin-VCSEL). Under hybrid electrical and optical pumping conditions, our VCSEL devices show polarization oscillations with frequencies far above the VCSEL's electrical modulation bandwidth. Using multiple optical pulses, we are able to excite and amplify these polarization oscillations. When specific phase and amplitude conditions for the optical excitation pulses are met, destructive interference leads to switch-off of the polarization oscillation, enabling the generation of controlled short polarization bursts.

  10. Vertical cavity surface emitting lasers emitting near 1.5 {mu}m with Sb-based reflectors

    SciTech Connect

    Blum, O.; Klem, J.F.; Vawter, G.A.

    1998-04-01

    We describe use of AlAsSb/AlGaAsSb lattice matched to InP for distributed Bragg reflectors. These structures are integral to several surface normal devices, in particular vertical cavity surface emitting lasers. The high refractive index ratio of these materials allows formation of a highly reflective mirror with relatively few mirror pairs. As a result, we have been able to show for the first time the 77K CW operation of an optically pumped, monolithic, all-epitaxial vertical cavity laser, emitting at 1.56 {mu}m.

  11. Optical pumping in a microfabricated Rb vapor cell using a microfabricated Rb discharge light source

    SciTech Connect

    Venkatraman, V.; Kang, S.; Affolderbach, C.; Mileti, G.; Shea, H.

    2014-02-03

    Miniature (optical pumping of alkali atoms, such as atomic clocks and magnetometers, today mostly employ vertical-cavity surface-emitting lasers as pump light sources. Here, we report on the demonstration of optical pumping in a microfabricated alkali vapor resonance cell using (1) a microfabricated Rb discharge lamp light source, as well as (2) a conventional glass-blown Rb discharge lamp. The microfabricated Rb lamp cell is a dielectric barrier discharge (DBD) light source, having the same inner cell volume of around 40 mm{sup 3} as that of the resonance cell, both filled with suitable buffer gases. A miniature (∼2 cm{sup 3} volume) test setup based on the M{sub z} magnetometer interrogation technique was used for observation of optical-radiofrequency double-resonance signals, proving the suitability of the microfabricated discharge lamp to introduce efficient optical pumping. The pumping ability of this light source was found to be comparable to or even better than that of a conventional glass-blown lamp. The reported results indicate that the micro-fabricated DBD discharge lamp has a high potential for the development of a new class of miniature atomic clocks, magnetometers, and quantum sensors.

  12. 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.

  13. Green monolithic II-VI vertical-cavity surface-emitting laser operating at room temperature

    NASA Astrophysics Data System (ADS)

    Kruse, C.; Ulrich, S. M.; Alexe, G.; Roventa, E.; Kröger, R.; Brendemühl, B.; Michler, P.; Gutowski, J.; Hommel, D.

    2004-02-01

    The realization of a monolithic all II-VI-based vertical cavity surface emitting laser (VCSEL) for the green spectral region is reported. Optically pumped lasing operation was achieved up to room temperature using a planar VCSEL structure. Taking advantage of distributed Bragg-reflectors based on MgS/Zn(Cd)Se superlattices as the low-refractive index material and ZnS0.06Se0.94 layers as the high-index material with a refractive index contrast of n = 0.6, a quality factor exceeding Q = 2000 is reached by using only 18 Bragg periods for the bottom DBR and 15 Bragg periods for the top DBR. The threshold power density is 0.32 MW/cm2 at a temperature of 10 K (emission wavelength 498.5 nm) and 1.9 MW/cm2 at room temperature (emission wavelength 502.3 nm).

  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. 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

    2016-01-04

    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.

  16. Extending the continuous tuning range of an external-cavity diode laser

    NASA Astrophysics Data System (ADS)

    Repasky, Kevin S.; Nehrir, Amin R.; Hawthorne, Justin T.; Switzer, Gregg W.; Carlsten, John L.

    2006-12-01

    The continuous tuning range of an external-cavity diode laser can be extended by making small corrections to the external-cavity length through an electronic feedback loop so that the cavity resonance condition is maintained as the laser wavelength is tuned. By maintaining the cavity resonance condition as the laser is tuned, the mode hops that typically limit the continuous tuning range of the external-cavity diode laser are eliminated. We present the design of a simple external-cavity diode laser based on the Littman-Metcalf external-cavity configuration that has a measured continuous tuning range of 1 GHz without an electronic feedback loop. To include the electronic feedback loop, a small sinusoidal signal is added to the drive current of the laser diode creating a small oscillation of the laser power. By comparing the phase of the modulated optical power with the phase of the sinusoidal drive signal using a lock-in amplifier, an error signal is created and used in an electronic feedback loop to control the external-cavity length. With electronic feedback, we find that the continuous tuning range can be extended to over 65 GHz. This occurs because the electronic feedback maintains the cavity resonance condition as the laser is tuned. An experimental demonstration of this extended tuning range is presented in which the external-cavity diode laser is tuned through an absorption feature of diatomic oxygen near 760 nm.

  17. Extending the continuous tuning range of an external-cavity diode laser.

    PubMed

    Repasky, Kevin S; Nehrir, Amin R; Hawthorne, Justin T; Switzer, Gregg W; Carlsten, John L

    2006-12-10

    The continuous tuning range of an external-cavity diode laser can be extended by making small corrections to the external-cavity length through an electronic feedback loop so that the cavity resonance condition is maintained as the laser wavelength is tuned. By maintaining the cavity resonance condition as the laser is tuned, the mode hops that typically limit the continuous tuning range of the external-cavity diode laser are eliminated. We present the design of a simple external-cavity diode laser based on the Littman-Metcalf external-cavity configuration that has a measured continuous tuning range of 1 GHz without an electronic feedback loop. To include the electronic feedback loop, a small sinusoidal signal is added to the drive current of the laser diode creating a small oscillation of the laser power. By comparing the phase of the modulated optical power with the phase of the sinusoidal drive signal using a lock-in amplifier, an error signal is created and used in an electronic feedback loop to control the external-cavity length. With electronic feedback, we find that the continuous tuning range can be extended to over 65 GHz. This occurs because the electronic feedback maintains the cavity resonance condition as the laser is tuned. An experimental demonstration of this extended tuning range is presented in which the external-cavity diode laser is tuned through an absorption feature of diatomic oxygen near 760 nm.

  18. External cavity diode laser based upon an FBG in an integrated optical fiber platform.

    PubMed

    Lynch, Stephen G; Holmes, Christopher; Berry, Sam A; Gates, James C; Jantzen, Alexander; Ferreiro, Teresa I; Smith, Peter G R

    2016-04-18

    An external cavity diode laser is demonstrated using a Bragg grating written into a novel integrated optical fiber platform as the external cavity. The cavity is fabricated using flame-hydrolysis deposition to bond a photosensitive fiber to a silica-on-silicon wafer, and a grating written using direct UV-writing. The laser operates on a single mode at the acetylene P13 line (1532.83 nm) with 9 mW output power. The noise properties of the laser are characterized demonstrating low linewidth operation (< 14 kHz) and superior relative intensity noise characteristics when compared to a commercial tunable external cavity diode laser.

  19. A compact chaotic laser device with a two-dimensional external cavity structure

    SciTech Connect

    Sunada, Satoshi Adachi, Masaaki; Fukushima, Takehiro; Shinohara, Susumu; Arai, Kenichi; Harayama, Takahisa

    2014-06-16

    We propose a compact chaotic laser device, which consists of a semiconductor laser and a two-dimensional (2D) external cavity for delayed optical feedback. The overall size of the device is within 230 μm × 1 mm. A long time delay sufficient for chaos generation can be achieved with the small area by the multiple reflections at the 2D cavity boundary, and the feedback strength is controlled by the injection current to the external cavity. We experimentally demonstrate that a variety of output properties, including chaotic output, can be selectively generated by controlling the injection current to the external cavity.

  20. Mode-locking of an InAs Quantum Dot Based Vertical External Cavity Surface Emitting Laser Using Atomic Layer Graphene

    DTIC Science & Technology

    2015-07-16

    wavelength range. The use of such QDs in vertical-cavity devices has resulted in high-power and broad gain bandwidth VECSELs in the NIR. In this project we...demonstrate growth and design of InAs QD based VECSELs in the 1200 -1300 nm wavelength range with record CW output powers. We utilize a resonant...the quality of the active region. We compare the performance of a VECSEL with 12 separate QD 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE 13

  1. Optically pumped 5 microm IV-VI VECSEL with Al-heat spreader.

    PubMed

    Rahim, M; Felder, F; Fill, M; Zogg, H

    2008-12-15

    Mid-infrared vertical external cavity surface emitting lasers (VECSELs) for 5 microm in wavelength have been realized. The active parts are of a simple structure, either a 2 microm thick PbTe gain layer or two 150 nm PbTe layers embedded in Pb(1-x)Eu(x)Te barriers. Epitaxial 2.5 pair Pb(1-y)Eu(y)Te/BaF(2) Bragg mirrors are employed to form the cavity, and an Al layer is deposited for improved heat dissipation. Emission up to 300 mW(p) is observed with microsecond pulses or 3 mW cw at 100 K is obtained. Quantum efficiency is up to 14%, and lasing occurs up to 175 K when pumped with a 1.55 microm wavelength pump laser.

  2. Analysis of Trace Gas Mixtures Using an External Cavity Quantum Cascade Laser Sensor

    SciTech Connect

    Phillips, Mark C.; Taubman, Matthew S.; Brumfield, Brian E.; Kriesel, Jason M.

    2015-07-01

    We measure and analyze mixtures of trace gases at ppb-ppm levels using an external cavity quantum cascade laser sensor with a 1-second response time. Accurate spectral fits are obtained in the presence of overlapping spectra.

  3. Rapid Swept-Wavelength External Cavity Quantum Cascade Laser for Open Path Sensing

    SciTech Connect

    Brumfield, Brian E.; Phillips, Mark C.

    2015-07-01

    A rapidly tunable external cavity quantum cascade laser system is used for open path sensing. The system permits acquisition of transient absorption spectra over a 125 cm-1 tuning range in less than 0.01 s.

  4. Hyperspectral microscopy using an external cavity quantum cascade laser and its applications for explosives detection

    SciTech Connect

    Phillips, Mark C.; Suter, Jonathan D.; Bernacki, Bruce E.

    2012-04-01

    A hyperspectral infrared microscope using external cavity quantum cascade laser illumination and a microbolometer focal plane array is used to characterize nanogram-scale particles of the explosives RDX, tetryl, and PETN at fast acquisition rates.

  5. Self-determining high-frequency oscillation from an external-cavity laser diode

    NASA Astrophysics Data System (ADS)

    Mercier, Émeric; Uy, Chi-Hak; Weicker, Lionel; Virte, Martin; Wolfersberger, Delphine; Sciamanna, Marc

    2016-12-01

    We report on a bifurcation mechanism following which an external-cavity laser diode emits regular oscillating output power at a high frequency. This frequency does not vary with the external-cavity length and it can be adjusted by varying the feedback strength. We observe this phenomenon numerically by investigating the external-cavity modes generated by a semiconductor laser subject to a phase-conjugate optical feedback. Particularly, we explore the effects of both the feedback rate and the time delay induced by the feedback on the frequency of the external-cavity modes. Counterintuitively, we evidence that having a short cavity does not necessarily yield oscillations at higher frequencies. We show that the key parameter in order to generate high-frequency solutions is the feedback rate. This parameter fixes the frequency of the solutions obtained independently of the time delay. We finally relate our observations to Hopf bifurcation phenomena.

  6. Optically pumped microplasma rare gas laser.

    PubMed

    Rawlins, W T; Galbally-Kinney, K L; Davis, S J; Hoskinson, A R; Hopwood, J A; Heaven, M C

    2015-02-23

    The optically pumped rare-gas metastable laser is a chemically inert analogue to three-state optically pumped alkali laser systems. The concept requires efficient generation of electronically excited metastable atoms in a continuous-wave (CW) electric discharge in flowing gas mixtures near atmospheric pressure. We have observed CW optical gain and laser oscillation at 912.3 nm using a linear micro-discharge array to generate metastable Ar(4s, 1s(5)) atoms at atmospheric pressure. We observed the optical excitation of the 1s(5) → 2p(9) transition at 811.5 nm and the corresponding fluorescence, optical gain and laser oscillation on the 2p(10) ↔ 1s(5) transition at 912.3 nm, following 2p(9)→2p(10) collisional energy transfer. A steady-state kinetics model indicates efficient collisional coupling within the Ar(4s) manifold.

  7. Terahertz graphene lasers: Injection versus optical pumping

    SciTech Connect

    Ryzhii, Victor; Otsuji, Taiichi; Ryzhii, Maxim; Mitin, Vladimir

    2013-12-04

    We analyze the formation of nonequilibrium states in optically pumped graphene layers and in forward-biased graphene structures with lateral p-i-n junctions and consider the conditions of population inversion and lasing. The model used accounts for intraband and interband relaxation processes as well as deviation of the optical phonon system from equilibrium. As shown, optical pumping suffers from a significant heating of both the electron-hole plasma and the optical phonon system, which can suppress the formation of population inversion. In the graphene structures with p-i-n junction, the injected electrons and holes have relatively low energies, so that the effect of cooling can be rather pronounced, providing a significant advantage of the injection pumping in realization of graphene terahertz lasers.

  8. Plasma channel optical pumping device and method

    DOEpatents

    Judd, O.P.

    1983-06-28

    A device and method are disclosed for optically pumping a gaseous laser using blackbody radiation produced by a plasma channel which is formed from an electrical discharge between two electrodes spaced at opposite longitudinal ends of the laser. A preionization device which can comprise a laser or electron beam accelerator produces a preionization beam which is sufficient to cause an electrical discharge between the electrodes to initiate the plasma channel along the preionization path. The optical pumping energy is supplied by a high voltage power supply rather than by the preionization beam. High output optical intensities are produced by the laser due to the high temperature blackbody radiation produced by the plasma channel, in the same manner as an exploding wire type laser. However, unlike the exploding wire type laser, the disclosed invention can be operated in a repetitive manner by utilizing a repetitive pulsed preionization device. 5 figs.

  9. Photonic crystal surface-emitting lasers

    SciTech Connect

    Chua, Song Liang; Lu, Ling; Soljacic, Marin

    2015-06-23

    A photonic-crystal surface-emitting laser (PCSEL) includes a gain medium electromagnetically coupled to a photonic crystal whose energy band structure exhibits a Dirac cone of linear dispersion at the center of the photonic crystal's Brillouin zone. This Dirac cone's vertex is called a Dirac point; because it is at the Brillouin zone center, it is called an accidental Dirac point. Tuning the photonic crystal's band structure (e.g., by changing the photonic crystal's dimensions or refractive index) to exhibit an accidental Dirac point increases the photonic crystal's mode spacing by orders of magnitudes and reduces or eliminates the photonic crystal's distributed in-plane feedback. Thus, the photonic crystal can act as a resonator that supports single-mode output from the PCSEL over a larger area than is possible with conventional PCSELs, which have quadratic band edge dispersion. Because output power generally scales with output area, this increase in output area results in higher possible output powers.

  10. Vertical-Cavity Surface-Emitting Lasers

    NASA Astrophysics Data System (ADS)

    Wilmsen, Carl W.; Temkin, Henryk; Coldren, Larry A.

    2002-01-01

    1. Introduction to VCSELs L. A. Coldren, C. W. Wilmsen and H. Temkin; 2. Fundamental issues in VCSEL design L. A. Coldren and Eric R. Hegblom; 3. Enhancement of spontaneous emission in microcavities E. F. Schubert and N. E. J. Hunt; 4. Epitaxy of vertical-cavity lasers R. P. Schneider Jr and Y. H. Young; 5. Fabrication and performance of vertical-cavity surface-emitting lasers Kent D. Choquette and Kent Geib; 6. Polarization related properties of vertical cavity lasers Dmitri Kuksenkov and Henryk Temkin; 7. Visible light emitting vertical cavity lasers Robert L. Thornton; 8. Long-wavelength vertical-cavity lasers Dubrakovo I. Babic, Joachim Piprek and John E. Bowers; 9. Overview of VCSEL applications Richard C. Williamson; 10. Optical interconnection applications and required characteristics Kenichi Kasahara; 11. VCSEL-based fiber-optic data communications Kenneth Hahn and Kirk Giboney; 12. VCSEL-based smart pixels for free space optoelectronic processing C. W. Wilmsen.

  11. Visible light surface emitting semiconductor laser

    DOEpatents

    Olbright, Gregory R.; Jewell, Jack L.

    1993-01-01

    A vertical-cavity surface-emitting laser is disclosed comprising a laser cavity sandwiched between two distributed Bragg reflectors. The laser cavity comprises a pair of spacer layers surrounding one or more active, optically emitting quantum-well layers having a bandgap in the visible which serve as the active optically emitting material of the device. The thickness of the laser cavity is m .lambda./2n.sub.eff where m is an integer, .lambda. is the free-space wavelength of the laser radiation and n.sub.eff is the effective index of refraction of the cavity. Electrical pumping of the laser is achieved by heavily doping the bottom mirror and substrate to one conductivity-type and heavily doping regions of the upper mirror with the opposite conductivity type to form a diode structure and applying a suitable voltage to the diode structure. Specific embodiments of the invention for generating red, green, and blue radiation are described.

  12. Multiperiod-grating surface-emitting lasers

    NASA Technical Reports Server (NTRS)

    Lang, Robert J. (Inventor)

    1992-01-01

    Surface-emitting distributed feedback (DFB) lasers are disclosed with hybrid gratings. A first-order grating is provided at one or both ends of the active region of the laser for retroreflection of light back into the active region, and a second-order or nonresonant grating is provided at the opposite end for coupling light out perpendicular to the surfaces of the laser or in some other selected direction. The gratings may be curved to focus light retroreflected into the active region and to focus light coupled out to a point. When so focused to a point, the DFB laser may be part of a monolithic read head for a laser recorded disk, or an optical coupler into an optical fiber.

  13. Optical pumping for nuclear beta decay

    NASA Astrophysics Data System (ADS)

    Behr, J. A.; Smale, S.; Craiciu, I.; Vantyghem, A.; Gorelov, A.; Anholm, M.; Behling, R. S.; Fenker, B.; Melconian, D.; Gwinner, G.; Friesen, D.

    2013-05-01

    For nuclear beta decay experiments to test the standard model, we must produce laser-cooled, polarized atoms with vector polarization of at least 99.9%, with knowledge of the polarization from atomic observables at 0.1% accuracy. We cycle on and off an AC MOT, and optically pump 37K atoms for 2 ms with trap off. We use circularly polarized light on the 4S1/2 --> 4P1/2 transition, using RF sidebands on a diode laser to excite transitions from both F=1 and F=2 ground states. We test techniques with stable 41K atoms, which have very similar hyperfine splitting to 37K. Optical pumping techniques include flipping spin state with liquid crystal variable retarders, 0.25 mm thick SiC substrate mirrors in front of the beta detectors, combining 769.9 D1 and 766.5 nm D2 with an angle-tuned narrow bandpass filter, relieving stress from conflat-compatible windows to minimize birefringence, and shifting the frequency of the light with the spin flips to compensate for Zeeman shifts. We must avoid coherent population trapping effects. The polarization is measured by the time dependence of the excited state population after optical pumping light is applied, probed by measuring fluorescence and by nonresonant photoionization. Supported by NSERC, NRC through TRIUMF.

  14. Bifurcation structure of cavity soliton dynamics in a vertical-cavity surface-emitting laser with a saturable absorber and time-delayed feedback

    NASA Astrophysics Data System (ADS)

    Schelte, Christian; Panajotov, Krassimir; Tlidi, Mustapha; Gurevich, Svetlana V.

    2017-08-01

    We consider a wide-aperture surface-emitting laser with a saturable absorber section subjected to time-delayed feedback. We adopt the mean-field approach assuming a single longitudinal mode operation of the solitary vertical-cavity surface-emitting laser (VCSEL). We investigate cavity soliton dynamics under the effect of time-delayed feedback in a self-imaging configuration where diffraction in the external cavity is negligible. Using bifurcation analysis, direct numerical simulations, and numerical path-continuation methods, we identify the possible bifurcations and map them in a plane of feedback parameters. We show that for both the homogeneous and localized stationary lasing solutions in one spatial dimension, the time-delayed feedback induces complex spatiotemporal dynamics, in particular a period doubling route to chaos, quasiperiodic oscillations, and multistability of the stationary solutions.

  15. Quantum well, beam deflecting surface emitting lasers

    NASA Technical Reports Server (NTRS)

    Kim, Jae H. (Inventor)

    1992-01-01

    This invention relates to surface emitting semiconductor lasers (SELs), with integrated 45 deg. beam deflectors. A SEL is formed on a wafer including vertical mirrors and 45 deg. beam deflectors formed in grooves by tilted ion beam etching. A SEL is a lattice matched, or unstrained, AlGaAs/GaAs GRINSCH SQW SEL. An alternate embodiment is shown, in which a SEL is lattice mismatched, strained or pseudomorphic, or InGaAs/AlGaAs GRINSCH SQW SEL which emits radiation at a wavelength to which its substrate is transparent. Both SELs exhibit high output power, low threshold current density, and relatively high efficiency, and each are processing compatible with conventional large scale integration technology. Such SELs may be fabricated in large numbers from single wafers. The novel features of this invention include the use of tilted ion beam etching to form a pair of grooves each including vertical mirrors and 45 deg. beam deflectors. The embodiment provides substantial circuit design flexibility because radiation may be coupled both up and/or down through the substrate.

  16. Phase dynamics in vertical-cavity surface-emitting lasers with delayed optical feedback and cross-polarized reinjection

    NASA Astrophysics Data System (ADS)

    Javaloyes, J.; Marconi, M.; Giudici, M.

    2014-08-01

    We study theoretically the nonlinear polarization dynamics of vertical-cavity surface-emitting lasers in the presence of an external cavity providing delayed optical feedback and cross-polarized reinjection. We show that, far from the laser threshold, the dynamics remains confined close to the equatorial plane of a Poincaré sphere with a fixed radius. It entails that the evolution of the system is described by two phase variables: the orientation phase of the quasilinear polarization and the optical phase of the field. We explore the complex modal structure given by the double reinjection configuration and how it evolves between the cases of single cross-polarized reinjection and single optical feedback, hence disclosing the relationship with the Lang-Kobayashi model. We also reinterpret the square-wave switching observed by J. Mulet et al. [Phys. Rev. A 76, 043801 (2007), 10.1103/PhysRevA.76.043801] in terms of phase kinks.

  17. Third order mode optically pumped semiconductor laser

    NASA Astrophysics Data System (ADS)

    De Rossi, A.; Semaltianos, N.; Chirlias, E.; Vinter, B.; Ortiz, V.; Berger, V.

    2002-06-01

    Lasing action on a third order waveguide mode is demonstrated at room temperature under optical pumping, in a specifically designed quantum well laser structure. The AlGaAs heterostructure involves barriers which ensure that the third order waveguide mode has a higher overlap with the single quantum well emitter than the fundamental mode. Third order mode operation of a laser structure opens the way to modal phase matched parametric down conversion inside the semiconductor laser itself. It is a first step towards the realization of semiconductor twin photon laser sources, needed for quantum information experiments.

  18. Optically pumped molecular bromine laser. Master's thesis

    SciTech Connect

    Morrison, J.W.

    1990-12-01

    An optically pumped molecular bromine laser was studied to investigate the quenching kinetics state of Br2. This included characterization of the pressure dependence of the laser output power. The approach was to excite molecular bromine in a sealed cell with a Nd:YAG pumped dye laser. Unresolved side fluorescence and amplified stimulated emission (ASE) spectra were recorded. ASE offered the advantage of a simpler optical system with no externally induced wavelength dependencies. Stimulated emission as a signal monitor offered greater resolution than side fluorescence spectra and facilitated spectroscopic assignment. (JS)

  19. Rovibrational cooling of molecules by optical pumping.

    PubMed

    Manai, I; Horchani, R; Lignier, H; Pillet, P; Comparat, D; Fioretti, A; Allegrini, M

    2012-11-02

    We demonstrate rotational and vibrational cooling of cesium dimers by optical pumping techniques. We use two laser sources exciting all the populated rovibrational states, except a target state that thus behaves like a dark state where molecules pile up thanks to absorption-spontaneous emission cycles. We are able to accumulate photoassociated cold Cs(2) molecules in their absolute ground state (v = 0, J = 0) with up to 40% efficiency. Given its simplicity, the method could be extended to other molecules and molecular beams. It also opens up general perspectives in laser cooling the external degrees of freedom of molecules.

  20. Optical pumping in a whispering-mode optical waveguide

    DOEpatents

    Kurnit, N.A.

    1981-08-11

    A device and method for optical pumping in a whispering mode optical waveguide are described. Both a helical ribbon and cylinder are disclosed which incorporate an additional curvature for confining the beam to increase intensity. An optical pumping medium is disposed in the optical path of the beam as it propagates along the waveguide. Optical pumping is enhanced by the high intensities of the beam and long interaction path lengths which are achieved in a small volume.

  1. Optical pumping in a whispering mode optical waveguide

    DOEpatents

    Kurnit, Norman A.

    1984-01-01

    A device and method for optical pumping in a whispering mode optical waveguide. Both a helical ribbon and cylinder are disclosed which incorporate an additional curvature for confining the beam to increase intensity. An optical pumping medium is disposed in the optical path of the beam as it propagates along the waveguide. Optical pumping is enhanced by the high intensities of the beam and long interaction pathlengths which are achieved in a small volume.

  2. Development of stable, narrow spectral line-width, fiber delivered laser source for spin exchange optical pumping

    DOE PAGES

    Liu, Bo; Tong, Xin; Jiang, Chenyang; ...

    2015-06-05

    In this study, we developed a stable, narrow spectral line-width, fiber delivered laser source for spin exchange optical pumping. An optimized external cavity equipped with an off-the-shelf volume holographic grating narrowed the spectral line-width of a 100 W high-power diode laser and stabilized the laser spectrum. The laser spectrum showed a high side mode suppression ratio of >30 dB and good long-term stability (center wavelength drifting within ±0.002 nm during 220 h of operation). Finally, our laser is delivered by a multimode fiber with power ~70 W, center wavelength of 794.77 nm, and spectral bandwidth of ~0.12 nm.

  3. Linewidth reduction of a broad-area laser diode array in a compound external cavity.

    PubMed

    Liu, Bo; Liu, Yun; Braiman, Yehuda

    2009-01-10

    A compound external cavity is designed and implemented to achieve a homogeneous spectrum distribution of broad area laser diodes in an array and to narrow the spectral linewidth of the entire array. The compound external cavity is composed of an optical coupler and a Littrow external cavity with a telescope along the fast axis. The inhomogeneous distribution of individual laser diodes spectrum generated by the "smile" effect was reduced by the telescope. The effective transverse coupling among individual laser diodes in an array was enhanced by the optical coupler, which further reduced the spectrum inhomogeneous distribution of the entire array. The spectral linewidth of a 49-emitter laser array is reduced to 0.1 nm at the output power of 12.5 W.

  4. Time delay signature concealment of optical feedback induced chaos in an external cavity semiconductor laser.

    PubMed

    Wu, Jia-Gui; Xia, Guang-Qiong; Tang, Xi; Lin, Xiao-Dong; Deng, Tao; Fan, Li; Wu, Zheng-Mao

    2010-03-29

    The time delay (TD) signature concealment of optical feedback induced chaos in an external cavity semiconductor laser is experimentally demonstrated. Both the evolution curve and the distribution map of TD signature are obtained in the parameter space of external feedback strength and injection current. The optimum parameter scope of the TD signature concealment is also specified. Furthermore, the approximately periodic evolution relation between TD signature and external cavity length is observed and indicates that the intrinsic relaxation oscillation of semiconductor laser may play an important role during the process of TD signature suppression.

  5. Linewidths below 100 kHz with external cavity diode lasers.

    PubMed

    Saliba, Sebastian D; Scholten, Robert E

    2009-12-20

    The linewidth of external cavity diode lasers (ECDLs) is an increasingly important characteristic for experiments in coherent optical communications and atomic physics. The Schawlow-Townes and time-averaged linewidths depend on free parameters of the design, such as cavity length, power, and grating characteristics. We show that the linewidth is also sensitive to the focus, set by the distance between the laser and the collimating lens, due to the effect on the external cavity backcoupling efficiency. By considering these factors, a simple ECDL can readily achieve linewidths below 100 kHz.

  6. Tunable external-cavity diode laser at 650 nm based on a transmission diffraction grating.

    PubMed

    Laurila, Toni; Joutsenoja, Timo; Hernberg, Rolf; Kuittinen, Markku

    2002-09-20

    A tunable external-cavity diode laser (ECDL) based on a transmission diffraction grating in a Littrow mount has been developed and characterized. A single-transverse-mode diode laser at 650 nm is used in an external-cavity configuration in which the transmission grating is used as a dispersive element to select the single longitudinal mode. The transmission diffraction grating is made with electron-beam lithography. A tunable true single-mode cw output power of >20 mW is obtained from the ECDL. The total wavelength tuning range is 12 nm, and the mode-hop-free continuous tunability is >20 GHz.

  7. Mode-hop-free tuning over 135 GHz of external cavity diode lasers without antireflection coating

    NASA Astrophysics Data System (ADS)

    Dutta, S.; Elliott, D. S.; Chen, Y. P.

    2012-03-01

    We report an external cavity diode laser (ECDL), using a diode whose front facet is not anti-reflection (AR) coated that has a mode-hop-free (MHF) tuning range greater than 135 GHz. We achieved this using a short external cavity and by simultaneously tuning the internal and external modes of the laser. We find that the precise location of the pivot point of the grating in our laser is less critical than commonly believed. The general applicability of the method, combined with the compact portable mechanical and electronic design, makes it well suited for both research and industrial applications.

  8. External-cavity diode laser in second-order Littrow configuration.

    PubMed

    Britzger, M; Khalaidovski, A; Hemb, B; Kley, E-B; Brückner, F; Rinkleff, R-H; Danzmann, K; Schnabel, R

    2012-08-01

    In this Letter, we propose and demonstrate an external-cavity diode laser in second-order Littrow configuration. This topology utilizes a low-efficiency diffraction grating to establish a high-finesse external cavity, strong optical feedback, a high polarization discrimination, and a circular TEM00 output mode. In our proof-of-concept experiment, we realized a cavity with a finesse of 1855, being, to the best of our knowledge, the highest value ever reported for a three-port-grating-coupled cavity. With optical feedback, the laser threshold of the laser diode employed was reduced by a factor of 4.

  9. Investigation on the thermal properties of volume Bragg grating in laser diodes with external cavities

    NASA Astrophysics Data System (ADS)

    Li, Zhiyong; Tan, Rongqing; Huang, Wei; Ye, Qing; Han, Gaoce; Li, Hui; Zheng, Yijun

    2016-08-01

    Thermal control of the volume Bragg grating (VBG) in the laser diode (LD) with the external cavity is critical for the tuning of the wavelength and the narrowing of the bandwidth. Based on finite element theories, thermal properties of the VBG were researched under different conditions of the LD illuminated area, laser power, gratings' working temperature, and heat convection. Both the VBGs in the external cavity of the LD bar and stack were considered in the experiments. The results show that higher working temperature of the VBG and adopting better heat convection cooling methods are beneficial to realize the uniformity of the VBG temperature distribution.

  10. Investigation on the thermal properties of volume Bragg grating in laser diodes with external cavities

    NASA Astrophysics Data System (ADS)

    Li, Zhiyong; Tan, Rongqing; Huang, Wei; Ye, Qing; Han, Gaoce; Li, Hui; Zheng, Yijun

    2016-10-01

    Thermal control of the volume Bragg grating (VBG) in the LD with the external cavity is critical for the tuning of the wavelength and the narrowing of the bandwidth. Based on finite element theories, thermal properties of the VBG were researched under different conditions of LD illumining area, laser power, gratings' working temperature and heat convection. Both the VBGs in the external cavity of LD bar and LD stack were considered in the experiments. The results show that higher working temperature of the VBG and adopting better heating convection cooling methods is beneficial to realize the uniformity of the VBG temperature distribution.

  11. Wavelength-modulation detection of acetylene with a near-infrared external-cavity diode laser

    NASA Astrophysics Data System (ADS)

    Oh, Daniel B.; Hovde, David Christian

    1995-10-01

    An external-cavity diode laser operating at 1500 nm was used to record the combination band of acetylene (C2H2). By combination of wavelength-modulation spectroscopy with a noise-canceler detection circuit, a minimum detectable absorbance of 4.8 \\times 10 -4 with a 300-ms time constant was achieved, although this result was limited by etalon fringes. When combined with this detection technique, continuous, widely tunable output from an external-cavity laser is ideally suited for high-resolution absorption spectroscopy with excellent sensitivity.

  12. Control of emitted light polarization in a 1310 nm dilute nitride spin-vertical cavity surface emitting laser subject to circularly polarized optical injection

    SciTech Connect

    Alharthi, S. S. Hurtado, A.; Al Seyab, R. K.; Henning, I. D.; Adams, M. J.; Korpijarvi, V.-M.; Guina, M.

    2014-11-03

    We experimentally demonstrate the control of the light polarization emitted by a 1310 nm dilute nitride spin-Vertical Cavity Surface Emitting Laser (VCSEL) at room temperature. This is achieved by means of a combination of polarized optical pumping and polarized optical injection. Without external injection, the polarization of the optical pump controls that of the spin-VCSEL. However, the addition of the externally injected signal polarized with either left- (LCP) or right-circular polarization (RCP) is able to control the polarization of the spin-VCSEL switching it at will to left- or right-circular polarization. A numerical model has been developed showing a very high degree of agreement with the experimental findings.

  13. 175 GHz, 400-fs-pulse harmonically mode-locked surface emitting semiconductor laser.

    PubMed

    Wilcox, Keith G; Quarterman, Adrian H; Apostolopoulos, Vasilis; Beere, Harvey E; Farrer, Ian; Ritchie, David A; Tropper, Anne C

    2012-03-26

    We report a harmonically mode-locked vertical external cavity surface emitting laser (VECSEL) producing 400 fs pulses at a repetition frequency of 175 GHz with an average output power of 300 mW. Harmonic mode-locking was established using a 300 µm thick intracavity single crystal diamond heat spreader in thermal contact with the front surface of the gain sample using liquid capillary bonding. The repetition frequency was set by the diamond microcavity and stable harmonic mode locking was achieved when the laser cavity length was tuned so that the laser operated on the 117th harmonic of the fundamental cavity. When an etalon placed intracavity next to the gain sample, but not in thermal contact was used pulse groups were observed. These contained 300 fs pulses with a spacing of 5.9 ps. We conclude that to achieve stable harmonic mode locking at repetition frequencies in the 100s of GHz range in a VECSEL there is a threshold pulse energy above which harmonic mode locking is achieved and below which groups of pulses are observed.

  14. CO.sub.2 optically pumped distributed feedback diode laser

    DOEpatents

    Rockwood, Stephen D.

    1980-01-01

    A diode laser optically pumped by a CO.sub.2 coherent source. Interference fringes generated by feeding the optical pumping beam against a second beam, periodically alter the reflectivity of the diode medium allowing frequency variation of the output signal by varying the impingent angle of the CO.sub.2 laser beams.

  15. Optically Pumped Subwavelength Lasers Operated at Room Temperature

    DTIC Science & Technology

    2012-05-06

    REPORT NACHOS Project Final Report_University of Michigan Optically pumped subwavelength lasers operated at room temperature 14. ABSTRACT 16. SECURITY...28-Feb-2011 NACHOS Project Final Report_University of Michigan Optically pumped subwavelength lasers operated at room temperature Report Title

  16. The Optically Pumped Cs Frequency Standard at the NRLM

    DTIC Science & Technology

    1987-12-01

    References 1. J.L. Picqu6, "Hyperfine optical pumping of a cesium atomic beam, and applications," Metrologia, vo1.13, pp.115-119, 1977. 2. M. Arditi and... Arditi , "A caesium beam atomic clock with laser optical pumping, as a potential frequency standard," Metrologia, vo1.18, pp.59-66, 1982. 4. G

  17. Initial-state dependence of the route to chaos of an external-cavity laser

    NASA Astrophysics Data System (ADS)

    Locquet, A.; Kim, Byungchil; Choi, Daeyoung; Li, Nianqiang; Citrin, D. S.

    2017-02-01

    External-cavity semiconductor lasers (ECLs), consisting of a laser diode in front of a mirror to reflect light back into the laser diode, are among the most important dynamical systems because of their ultrafast dynamics, their tunability, and the numerous existing applications. The dynamics of an ECL is greatly influenced by the existence and stability of numerous modes of the external cavity. In such high-dimensional nonlinear systems, numerous attractors, located around various modes of the external cavity, can coexist in phase space for a given set of parameters, a phenomenon called generalized multistability. In this work, we propose a procedure that allows one to select experimentally different modes of the external cavity as different initial states. We use this procedure to reveal experimentally generalized multistability in an ECL through the demonstration that different routes to chaos exist in an ECL, depending on the initial state selected. In particular, we show that the famous quasiperiodic route to chaos is only observed for specific choices of initial conditions.

  18. Intracavity Sensing via Compliance Voltage in an External Cavity Quantum Cascade Laser

    SciTech Connect

    Phillips, Mark C.; Taubman, Matthew S.

    2012-07-01

    We demonstrate a technique for gas phase spectroscopy and sensing by detecting changes in compliance voltage of an external cavity quantum cascade laser due to intracavity absorption. The technique is characterized and used to measure the absorption spectrum of water vapor and Freon-134a.

  19. Note: A compact external-cavity diode laser, using feedback from an optical fiber.

    PubMed

    Potnis, S; Edge, G J A; Jackson, S; Verma, M; Vutha, A C

    2017-09-01

    We demonstrate a simple and compact external cavity diode laser (ECDL), where light reflected from the tip of an optical fiber provides feedback, and an interference filter provides frequency selection. The ECDL combines ease of construction with robust operation and exhibits a linewidth of 50 kHz.

  20. Note: A compact external-cavity diode laser, using feedback from an optical fiber

    NASA Astrophysics Data System (ADS)

    Potnis, S.; Edge, G. J. A.; Jackson, S.; Verma, M.; Vutha, A. C.

    2017-09-01

    We demonstrate a simple and compact external cavity diode laser (ECDL), where light reflected from the tip of an optical fiber provides feedback, and an interference filter provides frequency selection. The ECDL combines ease of construction with robust operation and exhibits a linewidth of 50 kHz.

  1. Field-programmable gate array based locking circuit for external cavity diode laser frequency stabilization.

    PubMed

    Schwettmann, Arne; Sedlacek, Jonathon; Shaffer, James P

    2011-10-01

    We present a locking circuit for external cavity diode lasers implemented on a field-programmable gate array (FPGA). The main advantages over traditional non-FPGA-based locking circuits are rapid reconfigurability without any soldering and a friendly user interface. We characterize the lock quality by measuring the linewidth of a locked laser using electromagnetically induced transparency in a Rb vapor cell.

  2. Optically pumped rare-gas lasers

    SciTech Connect

    Mikheyev, P A

    2015-08-31

    The modern state of the research of a new promising optically pumped laser system with an active medium formed by metastable rare-gas atoms is briefly reviewed. The kinetics of these media is similar to that of laser media based on alkali metal vapour; however, the gas medium is inert. Metastable atoms can be produced in an electric discharge. As in alkali lasers, the specific laser power output under atmospheric pressure can be several hundreds of watts per 1 cm{sup 3}. The lasing wavelengths lie in the near-IR range and fall in the transparency window of the terrestrial atmosphere. This new concept makes it possible to develop a closed-cycle cw laser with megawatt power levels and high beam quality. (lasers)

  3. Optically pumped oxygen-iodine laser

    NASA Astrophysics Data System (ADS)

    Zagidullin, Marsel V.; Malyshev, Mikhail S.

    2017-01-01

    A novel optical pumping scheme considering a two-step irradiation by light at wavelengths near 500 nm and 1315 nm is proposed in this work. Radiation at 500 nm is used to dissociate about 1% of iodine molecules. The radiation at 1315 nm excites atomic iodine to the 2P1/2 state. Singlet oxygen molecules are produced via the energy exchange process I(2P1/2)+O2(X3Σ)-> I(2P3/2)+O2(a1Δ), while I(2P1/2)+O2(a1Δ) energy pooling produces b1Σ oxygen. I(2P3/2) and O2(1Σ) then accelerate the dissociation of I2. After gas dynamic cooling in supersonic nozzle, active medium may reach 100 W cm-2 and small signal gain of 0.01 cm-1.

  4. Velocity selective optical pumping resonance sign reversal

    NASA Astrophysics Data System (ADS)

    Krasteva, A.; Slavov, D.; Todorov, G.; Cartaleva, S.

    2013-03-01

    We report experimental and theoretical examinations of the peculiarities in Velocity Selective Optical Pumping (VSOP) resonance behavior at open and closed hyperfine transition spectra of Cs atoms (on the D2 line), confined in optical cell with thickness L = 6λ, where λ = 852 nm. For linear and circular polarizations of the irradiating light, open transitions exhibit reduced absorption (fluorescence) VSOP resonances whose contrast increases with atomic concentration and light intensity. However, in case of closed transition the situation is different, the enhanced absorption (fluorescence) VSOP resonance reverses its sign with the atomic concentration and light intensity. Theoretical analysis based on the density matrix formalism, taking into account the statistical tensors describing atomic population and longitudinal alignment, shows that the VSOP resonance sign reversal at the closed transition can be attributed to the efficiency reduction of population transfer by the spontaneous decay with atomic source temperature.

  5. Kinetics of optically pumped Kr metastables.

    PubMed

    Han, Jiande; Heaven, Michael C

    2015-04-01

    Optically-pumped atomic gas lasers that utilize metastable excited states of rare gas atoms (Rg(*)) have been demonstrated using both pulsed and CW pump sources. These devices resemble diode-pumped alkali vapor lasers, but have the advantage of using a chemically inert lasing medium. Collisional energy transfer is needed to sustain a population inversion, and He is used as the transfer agent. Consequently, values for the Kr(*)+He state-to-state energy transfer rate constants are needed for the analysis and prediction of laser performance characteristics. In the present study, we report He energy transfer rate constants for Kr(*) in the 5p[5/2](2), 5p[5/2](3), 5p[1/2](1), and 5s[3/2](1) states.

  6. High-speed vertical cavity surface emitting lasers

    SciTech Connect

    Lear, K.L.; Ochiai, M.; Hietala, V.M.

    1997-03-01

    High speed modulation and pulsing are reported for oxide-confined vertical cavity surface emitting laser diodes (VCSELs) with inverted doping and proton implantation to reduce the extrinsic limitations.

  7. Emission characteristics of high-gain GaN-based Vertical-Cavity Surface-Emitting Lasers

    NASA Astrophysics Data System (ADS)

    Weng, Guoen; Chen, Shaoqiang; Ito, Takashi; Akiyama, Hidefumi; Hu, Xiaobo; Zhang, Baoping

    2017-06-01

    GaN-based vertical-cavity surface-emitting lasers (VCSELs) with high optical gain and short cavity lifetime are favorable for the generation of ultra-short pulses in the blue and green regions. In our previous works, 6 and 2 picosecond short-pulses have been generated from gain-switched InGaN VCSELs with 3- and 10-period InGaN/GaN quantum wells (QWs) in the active layers by using an up-conversion measurement system. To further increase the gain of the VCSEL for the generation of even shorter pulses, 20-period InGaN/GaN QWs samples were fabricated. The emission characteristics of these high-gain VCSELs were investigated and analyzed under the optical pumping at room temperature.

  8. Recent Progress in Optically Pumped Magnetometers

    NASA Astrophysics Data System (ADS)

    Alexandrov, E. B.

    Optically pumped magnetometres (OPM) are known as the most precise instruments for scalar measurement of low magnetic fields, including those of the Earth's magnetic field. For a long time OPM could not compete, in absolute accuracy, with the proton precession magnetometers, being, at the same time, much more sensitive and fast. Nowadays, due to the considerable progress in the OPM performance, several types of OPM became much more accurate than the best proton magnetometer. During the last decade the main progress was associated with OPM of the following three types: (1) The narrow-line potassium Mx-OMP with the highest shot- noise-limited resolution (about 10 fT/Hz1/2) and with an absolute accuracy better than 0.1 nT; (2) The “tandem” Mx-Mz-type magnetometer with a narrow line potassium Mz unit of enhanced absolute accuracy (of about 10 pT); (3) The laser pumped 3He free-precession magnetometer of highest absolute accuracy and lowest energy consumption. Each of these three types has its own specific features, preferable in certain applications.

  9. Grating THz laser with optical pumping

    NASA Astrophysics Data System (ADS)

    Khoury, Jed; Haji-saeed, Bahareh; Woods, Charles; Kierstead, John

    2010-04-01

    In this paper, we present a design for a widely tunable solid-state optically and electrically pumped THz laser based on the Smith-Purcell free-electron laser. In the free-electron laser, an energetic electron beam pumps a metallic grating to generate surface plasmons. Our solid-state optically pumped design consists of a thin layer of dielectic, such as SiNx, sandwiched between a corrugated structure and a thin metal or semiconductor layer. The lower layer is for current streaming, and replaces the electron beam in the original design. The upper layer consists of one micro-grating for coupling the electromagnetic field in, another for coupling out, and a nano-grating for coupling with the current in the lower layer for electromagnetic field generation. The surface plasmon waves generated from the upper layer by an external electromagnetic field, and the lower layer by the applied current, are coupled. Emission enhancement occurs when the plasmonic waves in both layers are resonantly coupled.

  10. A High Bandwidth Optically Pumped Atomic Magnetometer

    NASA Astrophysics Data System (ADS)

    Jimenez-Martinez, Ricardo; Griffith, Clark W.; Knappe, Svenja; Kitching, John

    2009-10-01

    The measurement of magnetic fields has proved to be relevant in many realms of basic and applied science. Among the different techniques to measure magnetic fields, that of optically pumped atomic magnetometers has experienced considerable attention recently. This interest stems from the development of atomic magnetometers that achieve sensitivities in the sub-femto Tesla range, and the development of techniques that enable highly miniaturized, compact, with low-power consumption magnetometers. The sensitivity and bandwidth of atomic magnetometers is set by their spin coherence time, which in most magnetometers is limited by atomic collisions. Better sensitivities are achieved by suppressing the spin decoherence introduced by atomic collisions, but at a cost of lower bandwidth. For certain applications, a magnetometer with a high bandwidth is useful. Here we present a technique to achieve high bandwidth while preserving high sensitivity. We support the technique with table-top measurements showing that a bandwidth of 10 KHz and sensitivity of 10 pTrms/(Hz)^1/2 can be achieved in a compact device. We also highlight the current development of a miniature atomic magnetometer based on this technique.

  11. Magnetoencephalography with Optically Pumped Atomic Magnetometers

    NASA Astrophysics Data System (ADS)

    Schwindt, Peter; Colombo, Anthony; Jau, Yuan-Yu; Carter, Tony; Berry, Christopher; Young, Amber; McKay, Jim; Weisend, Michael

    2015-05-01

    We are working to develop a 36-channel array of optically pumped atomic magnetometers (AMs) to perform magnetoencephalography (MEG) with the goal of localizing magnetic sources within the human brain. The 36-channel array will consist of nine 4-channel sensor modules where the channels within each sensor will be spaced by 18 mm and each sensor will cover a 40 mm by 40 mm area of the head. In a previous 4-channel AM prototype, we demonstrated the measurement of evoked responses in both the auditory and somatosensory cortexes. This prototype had a 5 fT/Hz1/2 sensitivity. In the current version of the AM under development we are maintaining the previous sensitivity while implementing several improvements, including increasing the bandwidth from 20 Hz to more than 100 Hz, reducing the separation of the active volume of the AM from exterior of the sensor from 25 mm to 10 mm or less, and reducing the active sensor volume by a factor >10 to ~15 mm3. We will present results on the performance of our most recent AM prototype and progress toward developing a complete MEG system including a person-sized magnetic shield to provide a low-noise magnetic environment for MEG measurements.

  12. Remote chemical sensing by laser optical pumping

    SciTech Connect

    Stevens, C.G.; Magnotta, F.

    1996-08-01

    We are exploring a new approach to remote chemical identification that promises higher precision than can be achieved by conventional DIAL approaches. This technique also addresses and potentially solves the problem of detecting a target gas in the presence of an interfering gas or gases. This new approach utilizes an eye-safe infrared optical pumping pulse to deplete the population of a specific rotational level(s) and then sends probe pulses at the same or different wavelengths to interrogate the bleaching of the absorption. We have experimentally measured optical saturation fluence level at atmospheric pressure for HCl, and find this level to be {approximately}1 mJ/cm{sup 2}, significantly below eye-safe limits in agreement with calculations. Calculations have been performed on other molecules of interest with similar results. In the laboratory, using time-delay-replicated pulses at a single frequency we have made absorption measurements with precision levels routinely approaching 0.1% after averaging 200 laser pulses. These results as well as those of two other pulse experiments will be presented. 5 refs., 9 figs., 1 tab.

  13. Mode-hopping suppression of external cavity diode laser by mode matching.

    PubMed

    Gong, Hai; Liu, Zhigang; Zhou, Yangli; Zhang, Weibo; Lv, Tao

    2014-02-01

    Mode hopping is a critical performance limitation of external cavity diode lasers (ECDLs). We developed a method to suppress the mode hops by shifting the internal cavity longitudinal mode spectrum to match the other mode spectra. A model of longitudinal mode structure based on Littman-Metcalf configuration has been deduced for analyzing the characteristics of external cavity mode hop and internal cavity mode hop. The best mode matching point appears at the peak of output power when tuning the ECDL. Both the short-term and long-term wavelength stability were investigated in different laser diode current values while the tuning element maintains a fixed position. The experimental results demonstrated the effectiveness of the proposed mode matching methods for improving the mode stability and reducing the sensitivity to environment change.

  14. External cavity diode laser with frequency drift following natural variation in air pressure.

    PubMed

    Takamizawa, Akifumi; Yanagimachi, Shinya; Ikegami, Takeshi; Kawabata, Ryuzo

    2015-06-20

    A compact and mechanically very robust external cavity diode laser was made by removing any position adjusters such as precision screws and piezo actuators, taking advantage of a cat's eye retroreflector insensitive to misalignment. Under free-running operation during 150 h, the frequency drift followed natural variation in air pressure with a ratio of -66.6±0.1  MHz/hPa in a range between 1001.5 and 1013.6 hPa. The ratio was in good agreement with that estimated from variation in the effective cavity length derived from the relation between the pressure and the refractive index of air. These results indicate that an external cavity diode laser with predictable frequency drift was successfully created.

  15. Angle-resolved scattering spectroscopy of explosives using an external cavity quantum cascade laser

    SciTech Connect

    Suter, Jonathan D.; Bernacki, Bruce E.; Phillips, Mark C.

    2012-04-01

    Investigation of angle-resolved scattering from solid explosives residues on a car door for non-contact sensing geometries. Illumination with a mid-infrared external cavity quantum cascade laser tuning between 7 and 8 microns was detected both with a sensitive single point detector and a hyperspectral imaging camera. Spectral scattering phenomena were discussed and possibilities for hyperspectral imaging at large scattering angles were outlined.

  16. Extracavity and external cavity second-harmonic generation in a periodically poled silica fibre

    NASA Astrophysics Data System (ADS)

    Dontsova, E. I.; Kablukov, S. I.; Lobach, I. A.; Dostovalov, A. V.; Babin, S. A.; Gladyshev, A. V.; Dianov, E. M.; Corbary, C.; Ibsen, M.; Kazansky, P. G.

    2016-11-01

    We have studied second-harmonic generation (SHG) of a cw single-frequency ytterbium-doped fibre laser, using a periodically poled silica fibre as a nonlinear medium for frequency conversion. All-fibre external cavity SHG has been investigated for the first time. A twofold increase in second-harmonic power in a fibre ring cavity has been demonstrated and possibilities of further optimising the fibre scheme have been analysed.

  17. Power-efficient III-V/silicon external cavity DBR lasers.

    PubMed

    Zilkie, A J; Seddighian, P; Bijlani, B J; Qian, W; Lee, D C; Fathololoumi, S; Fong, J; Shafiiha, R; Feng, D; Luff, B J; Zheng, X; Cunningham, J E; Krishnamoorthy, A V; Asghari, M

    2012-10-08

    We report the design and characterization of external-cavity DBR lasers built with a III-V-semiconductor reflective-SOA with spot-size converter edge-coupled to SOI waveguides containing Bragg grating mirrors. The un-cooled lasers have wall-plug-efficiencies of up to 9.5% at powers of 6 mW. The lasers are suitable for making power efficient, hybrid WDM transmitters in a CMOS-compatible SOI optical platform.

  18. Fast Hyperspectral Imaging Using a Mid-Infrared Tunable External Cavity Quantum Cascade Laser

    SciTech Connect

    Phillips, Mark C.; Ho, Nicolas

    2008-04-23

    An active hyperspectral imaging system using an external cavity quantum cascade laser and a focal plane array acquiring images at 25 Hz from 985 cm-1 to 1075 cm-1 with a resolution of 0.3 cm 1 is demonstrated. The chemical imaging of gases is demonstrated in both static and dynamic cases. The system was also used to analyze liquid and solid samples.

  19. Theory of active mode locking of a semiconductor laser in an external cavity

    NASA Technical Reports Server (NTRS)

    Yeung, J. A.

    1981-01-01

    An analytical treatment is given for the active mode locking of a semiconductor laser in an external resonator. The width of the mode-locked pulses is obtained as a function of the laser and cavity parameters and the amount of frequency detuning. The effects of self-modulation and saturation are included in the treatment. The pulse output is compared with that obtained by a strong modulation of the laser diode with no external cavity.

  20. Actively controlled tuning of an external cavity diode laser by polarization spectroscopy.

    PubMed

    Führer, Thorsten; Stang, Denise; Walther, Thomas

    2009-03-30

    We report on an universal method to achieve and sustain a large mode-hop free tuning range of an external cavity diode laser. By locking one of the resonators using a closed loop control based on polarization spectroscopy while tuning the laser we achieved mode-hop free tuning of up to 130 GHz with a non AR-coated, off-the-shelf laser diode.

  1. Green pulsed lidar-radar emitter based on a multipass frequency-shifting external cavity.

    PubMed

    Zhang, Haiyang; Brunel, Marc; Romanelli, Marco; Vallet, Marc

    2016-04-01

    This paper investigates the radio frequency (RF) up-conversion properties of a frequency-shifting external cavity on a laser beam. We consider an infrared passively Q-switched pulsed laser whose intensity modulation results from the multiple round-trips in the external cavity, which contains a frequency shifter. The output beam undergoes optical second-harmonic generation necessary to reach the green wavelength. We model the pulse train using a rate-equation model to simulate the laser pulses, together with a time-delayed interference calculation taking both the diffraction efficiency and the Gaussian beam propagation into account. The predictions are verified experimentally using a diode-pumped Nd:YAG laser passively Q-switched by Cr4+:YAG whose pulse train makes multiple round-trips in a mode-matched external cavity containing an acousto-optic frequency shifter driven at 85 MHz. Second-harmonic generation is realized in a KTP crystal, yielding RF-modulated pulses at 532 nm with a modulation contrast of almost 100%. RF harmonics up to the 6th order (1.020 GHz) are observed in the green output pulses. Such a RF-modulated green laser may find applications in underwater detection and ranging.

  2. Red-emitting external cavity diode laser with high slope efficiency and narrow bandwidth

    NASA Astrophysics Data System (ADS)

    Park, Jiyeon; Song, Hong Joo; Na, Hong Man; Lee, Jun Ho; Yun, Ilgu

    2015-03-01

    External cavity diode laser with broad-area laser diode is operated up to the output power of 160 mW at the injection current of 850 mA and the bandwidth of 80 pm at a wavelength of 648 nm in external cavity. High slope efficiency of output power and narrow bandwidth using broad-area laser (BAL) diode, the width of active layer in the slow axis is too broad to select a specific wavelength. In this paper, more efficient wavelength selection method is investigated by confirming the tendency of grating grooves and designing to set up the wavelength dispersion direction along the fast axis of a solitary laser diode (LD) geometrically. Thus, the tunable external cavity diode laser module by using BAL diode is designed with an overall size of 49 mm x 52 mm x 48.5 mm. From injection current in the range of 650-900 mA, ECDL showed excellent wavelength locking behavior without a non-shift of the peak wavelength. Here, the tuning range is 4 nm with maintaining the narrow bandwidth of 80 pm and up to the output power of 100 mW. A side-mode-suppression of 36.5dB is also achieved at the output power of 160 mW and the injection current of 850 mA.

  3. Optical pumping of rubidium atoms frozen in solid argon

    NASA Astrophysics Data System (ADS)

    Kanagin, Andrew N.; Regmi, Sameer K.; Pathak, Pawan; Weinstein, Jonathan D.

    2013-12-01

    We have grown crystals of solid argon doped with rubidium atoms. The spectrum of the implanted atoms depends on the crystal-growth temperature and annealing history. We have used optical pumping to polarize the spin state of the implanted atoms and polarization spectroscopy to detect the spin state and measure the spin-relaxation time. In addition to the desired optical pumping, we also observed modification of the absorption spectrum of the rubidium due to the applied light.

  4. Effective bandwidth reduction for a high-power laser-diode array by an external-cavity technique.

    PubMed

    Zheng, Yujin; Kan, Hirofumi

    2005-09-15

    bandwidth of a high-power laser-diode array was effectively suppressed by use of an off-axis external-cavity technique. The external cavity consisted of a beam-transformation system and a pair of off-axis volume Bragg gratings. During operation at a drive current of 40 A, we reduced the bandwidth's full width at half-maximum from 3.3 to 0.24 nm (14-fold reduction) and achieved an output power of 20 W, or as much as 87% of the power radiated by a free-running laser-diode array without an external cavity.

  5. Preliminary surface-emitting laser logic device evaluation

    NASA Astrophysics Data System (ADS)

    Libby, S. I.; Parker, M. A.; Olbright, G. R.; Swanson, P. D.

    1993-03-01

    This report discusses the evaluation of a monolithically integrated heterojunction phototransistor and vertical-cavity surface-emitting laser, designated the surface-Emitting Laser Logic device (CELL). Included is a discussion of the device structure and theory of operation, test procedures, results, and conclusions. Also presented is the CELL's opto-electronic input/output characteristics which includes spectral analysis, characteristic emitted light versus current and current versus voltage curves, input wavelength tolerance, output wavelength sensitivity to bias current, and insensitivity to input wavelength and power within a specified range.

  6. Vertical-cavity surface-emitting laser device

    DOEpatents

    Hadley, G. Ronald; Lear, Kevin L.; Awyoung, Adelbert; Choquette, Kent D.

    1999-01-01

    A vertical-cavity surface-emitting laser device. The vertical-cavity surface-emitting laser (VCSEL) device comprises one or more VCSELs with each VCSEL having a mode-control region thereabout, with the mode-control region forming an optical cavity with an effective cavity length different from the effective cavity length within each VCSEL. Embodiments of the present invention can be formed as single VCSELs and as one- or two-dimensional arrays of VCSELs, with either an index-guided mode of operation or an index anti-guided mode of operation being defined by a sign of the difference in the two effective cavity lengths.

  7. Effective suppression of beam divergence for a high-power laser diode bar by an external-cavity technique.

    PubMed

    Gao, Xin; Zheng, Yujin; Kan, Hirofumi; Shinoda, Kazunori

    2004-02-15

    We describe effective suppression of beam divergence for a high-power laser diode bar by use of an external-cavity technique. Nineteen off-axis external-cavity laser diodes of the high-power laser diode are formed by feedback with a stripe mirror. At three times the threshold current, the diverging angle (1/e2) of the external-cavity laser diode bar is reduced to 1.5 degrees from 6.6 degrees (free running) with 14.1-W peak output power and 70.4% of the radiated power of the free-running state without the external cavity. This technique effectively improves the beam quality of the high-power laser diode bar.

  8. Two-Period Gratings For Surface-Emitting Lasers

    NASA Technical Reports Server (NTRS)

    Lang, Robert J.

    1991-01-01

    Grating surfaces having two spatial periods tailored to obtain desired proportions of output coupling and inward reflection. Solid-state lasers of type emitting light perpendicularly to their broad surfaces made more efficient. Same principle also applicable to "Annular-Bragg-Grating Surface-Emitting Laser", (NPO-17912).

  9. External-cavity beam combining of 4-channel quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Zhao, Yue; Zhang, Jin-Chuan; Zhou, Yu-Hong; Jia, Zhi-Wei; Zhuo, Ning; Zhai, Shen-Qiang; Wang, Li-Jun; Liu, Jun-Qi; Liu, Shu-Man; Liu, Feng-Qi; Wang, Zhan-Guo

    2017-09-01

    We demonstrate an external-cavity (EC) beam combining of 4-channel quantum cascade lasers (QCLs) with an output coupler which makes different QCL beams propagating coaxially. A beam combining efficiency of 35% (up to 75% near threshold) is obtained with a beam quality M2 of 5.5. A peak power of 0.64 W is achieved at a wavelength of 4.7 μm. The differences of spot characteristic between coupled and uncoupled are also showed in this letter. The QCLs in this EC system do not have heat crosstalk so that the system can be used for high power beam combining of QCLs.

  10. Intracavity measurement of liquid crystal layer thickness by wavelength tuning of an external cavity laser diode.

    PubMed

    Lan, Yu-Ping; Lin, Yea-Feng; Li, Yu-Tai; Pan, Ru-Pin; Lee, Chao-Kuei; Pan, Ci-Ling

    2005-10-03

    The gap of a planar-aligned liquid crystal (LC) cell is measured by a novel method: Monitoring the change in output wavelength of an external-cavity diode laser by varying the voltage driving the LC cell placed in the laser cavity. This method is particularly suitable for measurement of LC cells of small phase retardation. Measurement errors of +/-0.5 % and +/-0.6 % for 9.6-microm and 4.25-microm cells with phase retardations of 1.63 microm and 0.20 microm respectively are demonstrated.

  11. Infrared near-field spectroscopy of trace explosives using an external cavity quantum cascade laser.

    PubMed

    Craig, Ian M; Taubman, Matthew S; Lea, A Scott; Phillips, Mark C; Josberger, Erik E; Raschke, Markus B

    2013-12-16

    Utilizing a broadly-tunable external cavity quantum cascade laser for scattering-type scanning near-field optical microscopy (s-SNOM), we measure infrared spectra of particles of explosives by probing characteristic nitro-group resonances in the 7.1-7.9 µm wavelength range. Measurements are presented with spectral resolution of 0.25 cm(-1), spatial resolution of 25 nm, sensitivity better than 100 attomoles, and at a rapid acquisition time of 90 s per spectrum. We demonstrate high reproducibility of the acquired s-SNOM spectra with very high signal-to-noise ratios and relative noise of <0.02 in self-homodyne detection.

  12. Wavemeter uncertainty evaluation for the calibration of external cavity diode lasers

    NASA Astrophysics Data System (ADS)

    Outumuro, I.; Valencia, J. L.; Diz-Bugarin, J.; Blanco, J.; Dorrio, B. V.

    2014-08-01

    The uncertainty of a wavemeter has been evaluated taking into account all contributions. This wavemeter was developed to give traceability to the frequency of external cavity diode lasers. These lasers were stabilized and used as light source in the assembly of a new interferometric system for the gauge block calibration. The wavemeter experimental setup is also presented and is based in a Michelson interferometer, a He-Ne laser used as a reference wavelength and a Vernier counter that allowed us to reduce the uncertainty below 1ppm.

  13. Study of the stability and uncertainty of an external cavity diode laser through a Michelson wavemeter

    NASA Astrophysics Data System (ADS)

    Outumuro, I.; Valencia, J. L.; Diz-Bugarin, J.; Blanco, J.; Dorrío, B. V.

    2014-07-01

    A Michelson wavemeter was developed to test the accuracy and give traceability to the wavelength of external cavity diode lasers. These lasers were stabilized using a Littrow configuration and an iodine gas cell as frequency reference, and they will be used as light sources in the assembly of a new interferometric system for gauge block calibration. Previously, the uncertainty evaluation of the Michelson wavemeter with a Vernier counter had to be made, in which, as it is usual, the counting set starts and stops when the interference phases of the reference and unknown wavefronts coincide.

  14. Trace-gas sensing using the compliance voltage of an external cavity quantum cascade laser

    NASA Astrophysics Data System (ADS)

    Phillips, Mark C.; Taubman, Matthew S.

    2013-05-01

    We present experimental demonstration of a new chemical sensing technique based on intracavity absorption in an external cavity quantum cascade laser (ECQCL). This new technique eliminates the need for an infrared photodetector and gas cell by detecting the intracavity absorption spectrum in the compliance voltage of the laser device itself. To demonstrate and characterize the technique, we measure infrared absorption spectra of chemicals including acetone and Freon-134a. Sub-ppm detection limits in one second are achieved, with the potential for increased sensitivity after further optimization. The technique enables development of handheld, high-sensitivity, and high-accuracy trace gas sensors for in-field use.

  15. Quantum dot SOA/silicon external cavity multi-wavelength laser.

    PubMed

    Zhang, Yi; Yang, Shuyu; Zhu, Xiaoliang; Li, Qi; Guan, Hang; Magill, Peter; Bergman, Keren; Baehr-Jones, Thomas; Hochberg, Michael

    2015-02-23

    We report a hybrid integrated external cavity, multi-wavelength laser for high-capacity data transmission operating near 1310 nm. This is the first demonstration of a single cavity multi-wavelength laser in silicon to our knowledge. The device consists of a quantum dot reflective semiconductor optical amplifier and a silicon-on-insulator chip with a Sagnac loop mirror and microring wavelength filter. We show four major lasing peaks from a single cavity with less than 3 dB power non-uniformity and demonstrate error-free 4 × 10 Gb/s data transmission.

  16. Ring-resonator-integrated tunable external cavity laser employing EAM and SOA.

    PubMed

    Yoon, Ki-Hong; Kwon, O-Kyun; Kim, Ki Soo; Choi, Byung-Seok; Oh, Su Hwan; Kim, Hyun Su; Sim, Jae-Sik; Kim, Chul Soo

    2011-12-05

    We propose and demonstrate a tunable external cavity laser (ECL) composed of a polymer Bragg reflector (PBR) and integrated gain chip with gain, a ring resonator, an electro-absorption modulator (EAM), and a semiconductor optical amplifier (SOA). The cavity of the laser is composed of the PBR, gain, and ring resonator. The ring resonator reflects the predetermined wavelengths into the gain region and transmits the output signal into integrated devices such as the EAM and SOA. The output wavelength of the tunable laser is discretely tuned in steps of about 0.8 nm through the thermal-optic effect of the PBR and predetermined mode spacing of the ring resonator.

  17. Extreme intensity pulses in a semiconductor laser with a short external cavity.

    PubMed

    Reinoso, Jose A; Zamora-Munt, Jordi; Masoller, Cristina

    2013-06-01

    We present a numerical study of the pulses displayed by a semiconductor laser with optical feedback in the short-cavity regime, such that the external cavity round-trip time is shorter than the laser relaxation oscillation period. For certain parameters there are occasional pulses, which are high enough to be considered extreme events. We characterize the bifurcation scenario that gives rise to such extreme pulses and study the influence of noise. We demonstrate intermittency when the extreme pulses appear and hysteresis when the attractor that sustains these pulses is destroyed. We also show that this scenario is robust under the inclusion of noise.

  18. Hyperspectral Microscopy of Explosives Particles Using an External Cavity Quantum Cascade Laser

    SciTech Connect

    Phillips, Mark C.; Bernacki, Bruce E.

    2012-12-26

    Using infrared hyperspectral imaging, we demonstrate microscopy of small particles of the explosives compounds RDX, tetryl, and PETN with near diffraction-limited performance. The custom microscope apparatus includes an external cavity quantum cascade laser illuminator scanned over its tuning range of 9.13-10.53 µm in four seconds, coupled with a microbolometer focal plane array to record infrared transmission images. We use the hyperspectral microscopy technique to study the infrared absorption spectra of individual explosives particles, and demonstrate sub-nanogram detection limits.

  19. Narrow linewidth tunable external cavity diode laser using wide bandwidth filter

    NASA Astrophysics Data System (ADS)

    Thompson, Daniel J.; Scholten, Robert E.

    2012-02-01

    We demonstrate single mode operation of an external cavity diode laser (ECDL) employing an interference filter with multimode bandwidth for mode selection. A cateye reflector maximizes feedback efficiency and reduces susceptibility to intra-cavity optical misalignment. Narrow linewidths of 26 kHz are observed, and the laser can be tuned over 14 nm using a single 785 nm filter, without alteration of the output beam direction. The cateye reflector and filter allow a mechanically rigid design free of significant mechanical resonances, illustrated by comparison of the frequency noise spectrum with that of a common Littrow ECDL design using a diffraction grating and kinematic mount.

  20. 400 mW external cavity diode laser with narrowband emission at 445 nm.

    PubMed

    Ruhnke, N; Müller, A; Eppich, B; Maiwald, M; Sumpf, B; Erbert, G; Tränkle, G

    2014-07-01

    A high-power external cavity diode laser (ECDL) system with narrowband emission is presented. The system is based on a commercially available high-power GaN laser diode. For the ECDL, a maximum optical output power of 400 mW in continuous-wave operation with narrowband emission is achieved. Longitudinal mode selection is realized by using a surface diffraction grating in Littrow configuration. A spectral width of 20 pm at 445 nm with a side-mode suppression ratio larger than 40 dB is achieved. This concept enables diode laser systems suitable for subsequent nonlinear frequency conversion into the UV spectral range.

  1. External-cavity diode lasers with different devices and collimating optics.

    PubMed

    Kane, D M; Willis, A P

    1995-07-20

    Comparative operating characteristics of external-cavity diode lasers (ECDL's) with either a channel substrate planar device or a multi-quantum-well (MQW) device are presented. These include the output beam profile, which is significantly altered depending on the collimating lens used (either multielement or graded index), power versus injection-current characteristics, and the optical frequency and the rf spectra. The coherence lengths of the different laser diode-collimating-lens combinations in the ECDL are measured, and a new method for calculating the coupling coefficient and the coupled values of the internal quantum efficiency and the internal lumped loss is demonstrated for the MQW device.

  2. Frequency stabilization at the sub-kilohertz level of an external cavity diode laser.

    PubMed

    Bayrakli, Ismail

    2016-03-20

    A simple external cavity diode laser (ECDL) in a Littrow configuration was established and actively frequency-stabilized by using a side-of-fringe stabilization technique. A wavelength tuning range of 60 nm for the spectral range between 1000 and 1060 nm was demonstrated by rotating the diffraction grating. A sub-kilohertz frequency stabilization of the ECDL was achieved. The linewidth of the laser was narrowed from 160 kHz to 400 Hz by laser frequency locking to a flank of a Fabry-Perot interferometer peak.

  3. A Digital Phase Lock Loop for an External Cavity Diode Laser

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-Long; Tao, Tian-Jiong; Cheng, Bing; Wu, Bin; Xu, Yun-Fei; Wang, Zhao-Ying; Lin, Qiang

    2011-08-01

    A digital optical phase lock loop (OPLL) is implemented to synchronize the frequency and phase between two external cavity diode lasers (ECDL), generating Raman pulses for atom interferometry. The setup involves all-digital phase detection and a programmable digital proportional-integral-derivative (PID) loop in locking. The lock generates a narrow beat-note linewidth below 1 Hz and low phase-noise of 0.03rad2 between the master and slave ECDLs. The lock proves to be stable and robust, and all the locking parameters can be set and optimized on a computer interface with convenience, making the lock adaptable to various setups of laser systems.

  4. Narrow linewidth hybrid integrated external cavity diode laser for precision applications

    NASA Astrophysics Data System (ADS)

    Wei, Fang; Sun, Guangwei; Zhang, Li; Chen, Gaoting; Xin, Guofeng; Chen, Dijun; Cai, Haiwen

    2016-11-01

    A butterfly-packaged narrow-linewidth hybrid integrated external cavity diode laser module based on the polarization maintaining fiber Bragg grating is reported. The module emits at the wavelength of 1550 nm and provides 21 GHz of continuous tunability. It produces >= 20 mW of polarization maintaining fiber-coupled output power with intrinsic Lorentz linewidth <= 3 kHz and RIN <=140 dB/√Hz@100 kHz. To qualify the reliability of the laser module under harsh environmental conditions, random vibration test and high-low temperature cycling test are carried out, and no degradation of the power current characteristic is observed.

  5. Dual laser diode array emission coherently summed in an external cavity

    NASA Technical Reports Server (NTRS)

    Hemmati, Hamid; Abshire, James B.

    1987-01-01

    The output power from two ten-element laser diodes arrays has been efficiently summed in an external cavity to obtain a coherent, continuous wave beam. In this technique, laser emission from each front surface antireflection coated diode array is stimulated by injection of emission from a second such array. This method was also applied to single-element diode lasers. The output beam characteristics such as spectral distribution, far-field and near-field beam patterns, and overall efficiency have been measured.

  6. Characterization of an external cavity diode laser based ring cavity NICE-OHMS system.

    PubMed

    Bell, C L; Hancock, G; Peverall, R; Ritchie, G A D; van Helden, J H; van Leeuwen, N J

    2009-06-08

    The performance of an external cavity diode laser based noise immune cavity enhanced optical heterodyne molecular spectrometer is presented. To reduce the noise on the signal a ring cavity and a circuit to remove residual amplitude modulation on the pre-cavity laser radiation was implemented. We demonstrate a sensitivity of 4 x 10(-11) cm(-1) Hz(-1/2) using a cavity with a finesse of 2600 on a Doppler-broadened transition of CH(4) at 6610.063 cm(-1).

  7. 10-Gb/s direct modulation of polymer-based tunable external cavity lasers.

    PubMed

    Choi, Byung-Seok; Oh, Su Hwan; Kim, Ki Soo; Yoon, Ki-Hong; Kim, Hyun Soo; Park, Mi-Ran; Jeong, Jong Sool; Kwon, O-Kyun; Seo, Jun-Kyu; Lee, Hak-Kyu; Chung, Yun C

    2012-08-27

    We demonstrate a directly-modulated 10-Gb/s tunable external cavity laser (ECL) fabricated by using a polymer Bragg reflector and a high-speed superluminescent diode (SLD). The tuning range and output power of this ECL are measured to be >11 nm and 2.6 mW (@ 100 mA), respectively. We directly modulate this laser at 10 Gb/s and transmit the modulated signal over 20 km of standard single-mode fiber. The power penalty is measured to be <2.8 dB at the bit-error rate (BER) of 10(-10).

  8. Shift lens external-cavity diode laser for broad wavelength tuning and switching.

    PubMed

    Okamura, Hideki

    2010-04-15

    We propose an external-cavity laser diode that uses an electromagnetically actuated collimating lens for wavelength tuning. Because the wavelength in the grating equation is highly sensitive to the incident angle, a slight (approximately 1 microm) transverse displacement of the collimating lens induces a wavelength shift of approximately 1 nm. We experimentally demonstrate a single-mode, stable, reproducible, and cw tuning over a range of 8 nm. The wavelength is proportional to the current applied to the lens actuator, and no hysteresis is observed within the experimental error. By changing the current, we achieve fast and reproducible wavelength switching.

  9. Laser absorption spectroscopy based on a broadband external cavity quantum cascade laser

    NASA Astrophysics Data System (ADS)

    Sun, Juan; Liu, Ningwu; Deng, Hao; Ding, Junya; Sun, Jiancha; Zhang, Lei; Li, Jingsong

    2017-02-01

    A tunable diode laser absorption spectroscopy (TDLAS) system based on a broad band external cavity quantum cascade laser (ECQCL) near 7.78 μm was used to study volatile organic compounds (VOCs) measurements. Instead of using a standard infrared mercury cadmium telluride (MCT) detector, a quartz crystal tuning fork (QCTF) as a light detector was successfully used for laser signal detection. Fast Fourier transform (FFT) was used to extract vibration intensity information of QCTF. Primary results indicate that the new developed system has a good reproducibility, and a good agreement was obtained by comparing with data taken from standard spectroscopic database.

  10. Narrow linewidth tunable external cavity diode laser using wide bandwidth filter.

    PubMed

    Thompson, Daniel J; Scholten, Robert E

    2012-02-01

    We demonstrate single mode operation of an external cavity diode laser (ECDL) employing an interference filter with multimode bandwidth for mode selection. A cateye reflector maximizes feedback efficiency and reduces susceptibility to intra-cavity optical misalignment. Narrow linewidths of 26 kHz are observed, and the laser can be tuned over 14 nm using a single 785 nm filter, without alteration of the output beam direction. The cateye reflector and filter allow a mechanically rigid design free of significant mechanical resonances, illustrated by comparison of the frequency noise spectrum with that of a common Littrow ECDL design using a diffraction grating and kinematic mount.

  11. High performance external cavity InAs/InP quantum dot lasers

    NASA Astrophysics Data System (ADS)

    Chen, P.; Gong, Q.; Cao, C. F.; Li, S. G.; Wang, Y.; Liu, Q. B.; Yue, L.; Zhang, Y. G.; Feng, S. L.; Ma, C. H.; Wang, H. L.

    2011-03-01

    We report on high performance InAs/InP quantum dot tunable external cavity lasers (ECLs) operating in continuous-wave mode at room temperature. A tuning range of 70 nm has been achieved, covering the wavelengths from 1563 to 1633 nm. The threshold current densities are lower than 1625 A/cm2 in the tuning range. More than 23 mW output power was obtained at lasing wavelength of 1594 nm with an external differential quantum efficiency of 10.3%. An even wider tuning range of 98 nm has been obtained from the ECL based on the QD laser lasing in a longer wavelength.

  12. Optically pumped lasing in single crystals of organometal halide perovskites prepared by cast-capping method

    SciTech Connect

    Nguyen, Van-Cao; Katsuki, Hiroyuki; Yanagi, Hisao; Sasaki, Fumio

    2016-06-27

    A simple “cast-capping” method is adopted to prepare single-crystal perovskites of methyl ammonium lead bromide (CH{sub 3}NH{sub 3}PbBr{sub 3}). By capping a CH{sub 3}NH{sub 3}PbBr{sub 3} solution casted on one substrate with another substrate such as glass, mica, and distributed Bragg reflector (DBR), the slow evaporation of solvent enables large-size cubic crystals to grow between the two substrates. Under optical pumping, edge-emitting lasing is observed based on Fabry–Pérot resonation between parallel side facets of a strip-shaped crystal typically with a lateral cavity length of a few tens of μm. On the other hand, vertical-cavity surface-emitting lasing (VCSEL) is obtained from a planar crystal grown between two DBRs with a cavity thickness of a few μm. Simultaneous detection of those edge- and surface-emissions reveals that the threshold excitation fluence of VCSEL is higher than that of the edge-emitting lasing due to thickness gradient in the planar crystal.

  13. Analysis of bistability conditions between lasing and nonlasing states for a vertical-cavity surface-emitting laser with frequency-selective optical feedback using an envelope approximation

    SciTech Connect

    Naumenko, A. V.; Loiko, N. A.; Ackemann, T.

    2007-08-15

    The emission characteristics of a vertical-cavity surface-emitting laser (VCSEL) coupled to an external cavity with a diffraction grating as a frequency-selective element are theoretically analyzed. We introduce envelope functions for the set of external-cavity modes based on the loci of modes with extremal gain or frequency in the proper parameter space. Replacing the set of discrete stationary solutions by these envelope functions, simple analytical expressions are derived for the existence of bistability between a lasing state strongly affected by the feedback and a state close to the solitary laser emission (in particular the nonlasing state) and for the frequency of the VCSEL in the grating-controlled regime. It is shown how the initial jump of the laser intensity during abrupt turn-on can be maximized. By a control of the feedback change, the width of the hysteresis loop can be increased significantly. The scheme under consideration can be useful in all-optical photonic switching applications.

  14. Gain and lasing of optically pumped metastable rare gas atoms.

    PubMed

    Han, Jiande; Heaven, Michael C

    2012-06-01

    Optically pumped alkali vapor lasers are currently being developed in several laboratories. The objective is to construct high-powered lasers that also exhibit excellent beam quality. Considerable progress has been made, but there are technical challenges associated with the reactivity of the metal atoms. Rare gas atoms (Rg) excited to the np(5)(n+1)s (3)P(2) configuration are metastable and have spectral properties that are closely similar to those of the alkali metals. In principle, optically pumped lasers could be constructed using excitation of the np(5)(n+1)p←np(5)(n+1)s transitions. We have demonstrated this potential by observing gain and lasing for optically pumped Ar(*), Kr(*) and Xe(*). Three-level lasing schemes were used, with He or Ar as the collisional energy transfer agent that established the population inversion. These laser systems have the advantage of using inert reagents that are gases at room temperature.

  15. Spin-velocity correlations of optically pumped atoms

    NASA Astrophysics Data System (ADS)

    Marsland, R., III; McGuyer, B. H.; Olsen, B. A.; Happer, W.

    2012-08-01

    We present efficient theoretical tools for describing the optical pumping of atoms by light propagating at arbitrary directions with respect to an external magnetic field, at buffer-gas pressures that are small enough for velocity-selective optical pumping (VSOP) but large enough to cause substantial collisional relaxation of the velocities and the spin. These are the conditions for the sodium atoms at an altitude of about 100 km that are used as guidestars for adaptive optics in modern ground-based telescopes to correct for aberrations due to atmospheric turbulence. We use spin and velocity relaxation modes to describe the distribution of atoms in spin space (including both populations and coherences) and velocity space. Cusp kernels are used to describe velocity-changing collisions. Optical pumping operators are represented as a sum of poles in the complex velocity plane. Signals simulated with these methods are in excellent agreement with previous experiments and with preliminary experiments in our laboratory.

  16. Curved grating fabrication techniques for concentric-circle grating, surface-emitting semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Jordan, Rebecca H.; King, Oliver; Wicks, Gary W.; Hall, Dennis G.; Anderson, Erik H.; Rooks, Michael J.

    1993-01-01

    We describe the fabrication and operational characteristics of a novel, surface-emitting semiconductor laser that makes use of a concentric-circle grating to both define its resonant cavity and to provide surface emission. A properly fabricated circular grating causes the laser to operate in radially inward- and outward-going circular waves in the waveguide, thus, introducing the circular symmetry needed for the laser to emit a beam with a circular cross-section. The basic circular-grating-resonator concept can be implemented in any materials system; an AlGaAs/GaAs graded-index, separate confinement heterostructure (GRINSCH), single-quantum-well (SQW) semiconductor laser, grown by molecular beam epitaxy (MBE), was used for the experiments discussed here. Each concentric-circle grating was fabricated on the surface of the AlGaAs/GaAs semiconductor laser. The circular pattern was first defined by electron-beam (e-beam) lithography in a layer of polymethylmethacrylate (PMMA) and subsequently etched into the semiconductor surface using chemically-assisted (chlorine) ion-beam etching (CAIBE). We consider issues that affect the fabrication and quality of the gratings. These issues include grating design requirements, data representation of the grating pattern, and e-beam scan method. We provide examples of how these techniques can be implemented and their impact on the resulting laser performance. A comparison is made of the results obtained using two fundamentally different electron-beam writing systems. Circular gratings with period lambda = 0.25 microns and overall diameters ranging from 80 microns to 500 microns were fabricated. We also report our successful demonstration of an optically pumped, concentric-circle grating, semiconductor laser that emits a beam with a far-field divergence angle that is less than one degree. The emission spectrum is quite narrow (less than 0.1 nm) and is centered at wavelength lambda = 0.8175 microns.

  17. Liquid detection with InGaAsP semiconductor lasers having multiple short external cavities.

    PubMed

    Zhu, X; Cassidy, D T

    1996-08-20

    A liquid detection system consisting of a diode laser with multiple short external cavities (MSXC's) is reported. The MSXC diode laser operates single mode on one of 18 distinct modes that span a range of 72 nm. We selected the modes by setting the length of one of the external cavities using a piezoelectric positioner. One can measure the transmission through cells by modulating the injection current at audio frequencies and using phase-sensitive detection to reject the ambient light and reduce 1/f noise. A method to determine regions of single-mode operation by the rms of the output of the laser is described. The transmission data were processed by multivariate calibration techniques, i.e., partial least squares and principal component regression. Water concentration in acetone was used to demonstrate the performance of the system. A correlation coefficient of R(2) = 0.997 and 0.29% root-mean-square error of prediction are found for water concentration over the range of 2-19%.

  18. Trace-gas sensing using the compliance voltage of an external cavity quantum cascade laser

    SciTech Connect

    Phillips, Mark C.; Taubman, Matthew S.

    2013-06-04

    Quantum cascade lasers (QCLs) are increasingly being used to detect, identify, and measure levels of trace gases in the air. External cavity QCLs (ECQCLs) provide a broadly-tunable infrared source to measure absorption spectra of chemicals and provide high detection sensitivity and identification confidence. Applications include detecting chemical warfare agents and toxic industrial chemicals, monitoring building air quality, measuring greenhouse gases for atmospheric research, monitoring and controlling industrial processes, analyzing chemicals in exhaled breath for medical diagnostics, and many more. Compact, portable trace gas sensors enable in-field operation in a wide range of platforms, including handheld units for use by first responders, fixed installations for monitoring air quality, and lightweight sensors for deployment in unmanned aerial vehicles (UAVs). We present experimental demonstration of a new chemical sensing technique based on intracavity absorption in an external cavity quantum cascade laser (ECQCL). This new technique eliminates the need for an infrared photodetector and gas cell by detecting the intracavity absorption spectrum in the compliance voltage of the laser device itself. To demonstrate and characterize the technique, we measure infrared absorption spectra of chemicals including water vapor and Freon-134a. Sub-ppm detection limits in one second are achieved, with the potential for increased sensitivity after further optimization. The technique enables development of handheld, high-sensitivity, and high-accuracy trace gas sensors for in-field use.

  19. Measurement of Broad Absorption Features Using a Tunable External Cavity Quantum Cascade Laser

    SciTech Connect

    Phillips, Mark C.; Myers, Tanya L.; Wojcik, Michael D.; Cannon, Bret D.; Taubman, Matthew S.; Scott, David C.

    2007-09-25

    We demonstrate the use of a tunable external cavity quantum cascade laser system for measurement of broad absorption features in the mid-infrared spectral region. The thermoelectrically cooled external cavity laser was tuned over a 65 cm-1 range centered at 8.7 microns using stepper motor control. Pulsing the laser at a high duty cycle provided 3-5 mW average output power over the tuning range, and enabled phase-sensitive detection of amplitude-modulated signals. We used the laser system to measure the absorption spectra of Freon-125 using a Herriott cell. In addition, the absorption spectrum of water in the laboratory air was measured. The measurements showed excellent agreement with reference spectra, in both wavelength and amplitude. The measured scan resolution of 0.14 cm-1 is suitable for measurement of the absorption features of complex molecules as well as simple molecules with atmospherically broadened lines. We discuss the limits to the scan resolution due to effects of spectral chirp and mode-hops during pulsed operation.

  20. A digital frequency stabilization system of external cavity diode laser based on LabVIEW FPGA

    NASA Astrophysics Data System (ADS)

    Liu, Zhuohuan; Hu, Zhaohui; Qi, Lu; Wang, Tao

    2015-10-01

    Frequency stabilization for external cavity diode laser has played an important role in physics research. Many laser frequency locking solutions have been proposed by researchers. Traditionally, the locking process was accomplished by analog system, which has fast feedback control response speed. However, analog system is susceptible to the effects of environment. In order to improve the automation level and reliability of the frequency stabilization system, we take a grating-feedback external cavity diode laser as the laser source and set up a digital frequency stabilization system based on National Instrument's FPGA (NI FPGA). The system consists of a saturated absorption frequency stabilization of beam path, a differential photoelectric detector, a NI FPGA board and a host computer. Many functions, such as piezoelectric transducer (PZT) sweeping, atomic saturation absorption signal acquisition, signal peak identification, error signal obtaining and laser PZT voltage feedback controlling, are totally completed by LabVIEW FPGA program. Compared with the analog system, the system built by the logic gate circuits, performs stable and reliable. User interface programmed by LabVIEW is friendly. Besides, benefited from the characteristics of reconfiguration, the LabVIEW program is good at transplanting in other NI FPGA boards. Most of all, the system periodically checks the error signal. Once the abnormal error signal is detected, FPGA will restart frequency stabilization process without manual control. Through detecting the fluctuation of error signal of the atomic saturation absorption spectrum line in the frequency locking state, we can infer that the laser frequency stability can reach 1MHz.

  1. Microfabricated optically pumped magnetometer arrays for biomedical imaging

    NASA Astrophysics Data System (ADS)

    Perry, A. R.; Sheng, D.; Krzyzewski, S. P.; Geller, S.; Knappe, S.

    2017-02-01

    Optically-pumped magnetometers have demonstrated magnetic field measurements as precise as the best superconducting quantum interference device magnetometers. Our group develops miniature alkali atom-based magnetic sensors using microfabrication technology. Our sensors do not require cryogenic cooling, and can be positioned very close to the sample, making these sensors an attractive option for development in the medical community. We will present our latest chip-scale optically-pumped gradiometer developed for array applications to image magnetic fields from the brain noninvasively. These developments should lead to improved spatial resolution, and potentially sensitive measurements in unshielded environments.

  2. Unidirectionality of an optically pumped far infrared ring laser

    NASA Astrophysics Data System (ADS)

    Matsushima, Kyoji; Higashida, Noriyoshi; Sokabe, Noburu; Ariyasu, Tomio

    1995-02-01

    An experimental and theoretical investigation has been made on the unidirectional operation of an optically pumped far infrared ring laser. A ring laser operating on the 119 μm line of CH 3OH experiences reversal of output direction in either case of (a) the pump frequency being tuned across the line center of the infrared pump transition or (b) the fir cavity being tuned across the far infrared line center. A model based on two-mode laser theory predicts the output directionality of the optically pumped fir ring laser.

  3. Record Pulsed Power Demonstration of a 2 micron GaSb-Based Optically Pumped Semiconductor Laser Grown Lattice-Mismatched on an AlAs/GaAs Bragg Mirror and Substrate (Postprint)

    DTIC Science & Technology

    2009-09-01

    semiconductor disk lasers OPSL or, equivalently, vertical external cavity surface emitting semi- conductor lasers VECSEL , are emerging as novel sources...wavelengths in TEM00 beams. Direct genera- tion of red light at 670 nm with powers close to 0.5 W has also been demonstrated.4 These VECSEL structures...growth of InGaSb QW stacks on AlGaSb/GaSb Bragg mirrors. The latter have been employed to demonstrate 3–5 W VECSEL lasing between 2 and 2.3 m.5 Two

  4. Vertical-cavity surface-emitting laser device

    DOEpatents

    Hadley, G.R.; Lear, K.L.; Awyoung, A.; Choquette, K.D.

    1999-05-11

    A vertical-cavity surface-emitting laser device is disclosed. The vertical-cavity surface-emitting laser (VCSEL) device comprises one or more VCSELs with each VCSEL having a mode-control region thereabout, with the mode-control region forming an optical cavity with an effective cavity length different from the effective cavity length within each VCSEL. Embodiments of the present invention can be formed as single VCSELs and as one- or two-dimensional arrays of VCSELs, with either an index-guided mode of operation or an index anti-guided mode of operation being defined by a sign of the difference in the two effective cavity lengths. 10 figs.

  5. Electrically injected visible vertical cavity surface emitting laser diodes

    DOEpatents

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

    1994-09-27

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

  6. Electrically injected visible vertical cavity surface emitting laser diodes

    DOEpatents

    Schneider, Richard P.; Lott, James A.

    1994-01-01

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

  7. Repetition-frequency-tunable mode-locked surface emitting semiconductor laser between 2.78 and 7.87 GHz.

    PubMed

    Wilcox, Keith G; Quarterman, Adrian H; Beere, Harvey E; Ritchie, David A; Tropper, Anne C

    2011-11-07

    We report a repetition frequency tunable, passively mode-locked vertical-external-cavity surface-emitting semiconductor laser (VECSEL) with continuous repetition frequency tuning between 2.78 and 7.87 GHz using mechanical tuning of the laser cavity length. The laser emits near-transform-limited, sub-500-fs pulses over almost an octave tuning range between 2.78 and 5 GHz. At repetition rates above 6 GHz the pulse duration increases to ~2.5 ps. Over the entire tuning range the laser emits an average output power of 40 ± 5 mW in a fundamental transverse mode. The change in pulse duration highlights a change in the dominant modelocking mechanism which forms the pulses. At high repetition frequencies the pulse duration is set by the saturable absorber recovery time. At low repetition frequencies the fluence and peak intensity on the SESAM increases to a point where the fast pulse shaping mechanisms of the optical Stark effect and carrier thermalization dominate the pulse shortening.

  8. Narrow-line external cavity diode laser micro-packaging in the NIR and MIR spectral range

    NASA Astrophysics Data System (ADS)

    Jiménez, A.; Milde, T.; Staacke, N.; Aßmann, C.; Carpintero, G.; Sacher, J.

    2017-07-01

    Narrow-linewidth tunable diode lasers are an important tool for spectroscopic instrumentation. Conventional external cavity diode lasers offer high output power and narrow linewidth. However, most external cavity diode lasers are designed as laboratory instrument and do not allow portability. In comparison, other commonly used lasers, like distributed feedback lasers (DFB) that are capable of driving a handheld device, are limited in power and show linewidths which are not sufficiently narrow for certain applications. We present new miniaturized types of tunable external cavity diode laser which overcome the drawbacks of conventional external cavity diode lasers and which preserve the advantages of this laser concept. Three different configurations are discussed in this article. The three types of miniaturized external cavity diode laser systems achieve power values of more than 50 mW within the 1.4 μm water vapor absorption band with excellent side-mode suppression and linewidth below 100 kHz. Typical features outstand with respect to other type of laser systems which are of extended use such as DFB laser diodes. The higher output power and the lower linewidth will enable a higher sensitivity and resolution for a wide range of applications.

  9. Electronic displays using optically pumped luminescent semiconductor nanocrystals

    DOEpatents

    Weiss, Shimon; Schlamp, Michael C.; Alivisatos, A. Paul

    2010-04-13

    A multicolor electronic display is based on an array of luminescent semiconductor nanocrystals. Nanocrystals which emit light of different colors are grouped into pixels. The nanocrystals are optically pumped to produce a multicolor display. Different sized nanocrystals are used to produce the different colors. A variety of pixel addressing systems can be used.

  10. Electronic displays using optically pumped luminescent semiconductor nanocrystals

    DOEpatents

    Weiss, Shimon; Schlam, Michael C; Alivisatos, A. Paul

    2014-03-25

    A multicolor electronic display is based on an array of luminescent semiconductor nanocrystals. Nanocrystals which emit tight of different colors are grouped into pixels. The nanocrystals are optically pumped to produce a multicolor display. Different sized nanocrystals are used to produce the different colors. A variety of pixel addressing systems can be used.

  11. Electronic displays using optically pumped luminescent semiconductor nanocrystals

    SciTech Connect

    Weiss, Shimon; Schlamp, Michael C.; Alivisatos, Paul A.

    2015-11-10

    A multicolor electronic display is based on an array of luminescent semiconductor nanocrystals. Nanocrystals which emit tight of different colors are grouped into pixels. The nanocrystals are optically pumped to produce a multicolor display. Different sized nanocrystals are used to produce the different colors. A variety of pixel addressing systems can be used.

  12. Electronic displays using optically pumped luminescent semiconductor nanocrystals

    DOEpatents

    Weiss, Shimon; Schlamp, Michael C; Alivisatos, A. Paul

    2014-02-11

    A multicolor electronic display is based on an array of luminescent semiconductor nanocrystals. Nanocrystals which emit light of different colors are grouped into pixels. The nanocrystals are optically pumped to produce a multicolor display. Different sized nanocrystals are used to produce the different colors. A variety of pixel addressing systems can be used.

  13. Electronic displays using optically pumped luminescent semiconductor nanocrystals

    DOEpatents

    Weiss, Shimon; Schlamp, Michael C.; Alivisatos, A. Paul

    2011-09-27

    A multicolor electronic display is based on an array of luminescent semiconductor nanocrystals. Nanocrystals which emit light of different colors are grouped into pixels. The nanocrystals are optically pumped to produce a multicolor display. Different sized nanocrystals are used to produce the different colors. A variety of pixel addressing systems can be used.

  14. Electronic displays using optically pumped luminescent semiconductor nanocrystals

    DOEpatents

    Weiss, Shimon; Schlamp, Michael C.; Alivisatos, A. Paul

    2005-03-08

    A multicolor electronic display is based on an array of luminescent semiconductor nanocrystals. Nanocrystals which emit light of different colors are grouped into pixels. The nanocrystals are optically pumped to produce a multicolor display. Different sized nanocrystals are used to produce the different colors. A variety of pixel addressing systems can be used.

  15. Electronic displays using optically pumped luminescent semiconductor nanocrystals

    DOEpatents

    Weiss, Shimon; Schlamp, Michael C.; Alivisatos, A. Paul

    2015-06-23

    A multicolor electronic display is based on an array of luminescent semiconductor nanocrystals. Nanocrystals which emit light of different colors are grouped into pixels. The nanocrystals are optically pumped to produce a multicolor display. Different sized nanocrystals are used to produce the different colors. A variety of pixel addressing systems can be used.

  16. Phase dynamics in a Doppler broadened optically-pumped laser

    NASA Astrophysics Data System (ADS)

    Roldán, E.; de Valcárcel, G. J.; Vilaseca, R.; Silva, F.; Pujol, J.; Corbalán, R.; Laguarta, F.

    1989-11-01

    The dynamic behavior of the phase of the generated field in a Doppler-broadened optically-pumped far-infrared laser is theoretically investigated for the first time. The phase undergoes sudden jumps of approximately π radians, which allow to establish the actual symmetry of the main attractor in the phase space, explaining the heteroclynic character of the chaotic behavior observed in experiments.

  17. Quantum mechanical features of optically pumped CW FIR lasers

    NASA Technical Reports Server (NTRS)

    Seligson, D.; Leite, J. R. R.; Sanchez, A.; Feld, M. S.; Ducloy, M.

    1977-01-01

    Quantum mechanical predictions for the gain of an optically pumped CW FIR laser are presented for cases in which one or both of the pump and FIR transitions are pressure or Doppler broadened. The results are compared to those based on the rate equation model. Some of the quantum mechanical predictions are verified in CH3OH.

  18. Note: Demonstration of an external-cavity diode laser system immune to current and temperature fluctuations.

    PubMed

    Miao, Xinyu; Yin, Longfei; Zhuang, Wei; Luo, Bin; Dang, Anhong; Chen, Jingbiao; Guo, Hong

    2011-08-01

    We demonstrate an external-cavity laser system using an anti-reflection coated laser diode as gain medium with about 60 nm fluorescence spectrum, and a Rb Faraday anomalous dispersion optical filter (FADOF) as frequency-selecting element with a transmission bandwidth of 1.3 GHz. With 6.4% optical feedback, a single stable longitudinal mode is obtained with a linewidth of 69 kHz. The wavelength of this laser is operating within the center of the highest transmission peak of FADOF over a diode current range from 55 mA to 142 mA and a diode temperature range from 15 °C to 35 °C, thus it is immune to the fluctuations of current and temperature.

  19. External cavity quantum cascade lasers with ultra rapid acousto-optic tuning

    SciTech Connect

    Lyakh, A. Barron-Jimenez, R.; Dunayevskiy, I.; Go, R.; Patel, C. Kumar N.

    2015-04-06

    We report operation of tunable external cavity quantum cascade lasers with emission wavelength controlled by an acousto-optic modulator (AOM). A long-wave infrared quantum cascade laser wavelength tuned from ∼8.5 μm to ∼9.8 μm when the AOM frequency was changed from ∼41MHz to ∼49 MHz. The laser delivered over 350 mW of average power at the center of the tuning curve in a linewidth of ∼4.7 cm{sup −1}. Measured wavelength switching time between any two wavelengths within the tuning range of the QCL was less than 1 μs. Spectral measurements of infrared absorption features of Freon demonstrated a capability of obtaining complete spectral data in less than 20 μs.

  20. Littrow-type external-cavity blue laser for holographic data storage

    NASA Astrophysics Data System (ADS)

    Tanaka, Tomiji; Takahashi, Kazuo; Sako, Kageyasu; Kasegawa, Ryo; Toishi, Mitsuru; Watanabe, Kenjiro; Samuels, David; Takeya, Motonobu

    2007-06-01

    An external-cavity laser with a wavelength of 405 nm and an output of 80 mW has been developed for holographic data storage. The laser has three states: the first is a perfect single mode, whose coherent length is 14 m; the second is a three-mode state with a coherent length of 3 mm; and the third is a six-mode state with a coherent length of 0.3 mm. The first and second states are available for angular-multiplexing recording; all states are available for coaxial multiplexing recording. Due to its short wavelength, the recording density is higher than that of a 532 nm laser.

  1. Mid-infrared gas absorption sensor based on a broadband external cavity quantum cascade laser.

    PubMed

    Sun, Juan; Deng, Hao; Liu, Ningwu; Wang, Hongliang; Yu, Benli; Li, Jingsong

    2016-12-01

    We developed a laser absorption sensor based on a pulsed, broadband tunable external cavity quantum cascade laser (ECQCL) centered at 1285 cm(-1). Unlike traditional infrared spectroscopy system, a quartz crystal tuning fork (QCTF) as a light detector was used for laser signal detection. Fast Fourier transform was applied to extract vibration intensity information of QCTF. The sensor system is successfully tested on nitrous oxide (N2O) spectroscopy measurements and compared with a standard infrared detector. The wide wavelength tunability of ECQCL will allow us to access the fundamental vibrational bands of many chemical agents, which are well-suited for trace explosive, chemical warfare agent, and toxic industrial chemical detection and spectroscopic analysis.

  2. Reflection-absorption infrared spectroscopy of thin films using an external cavity quantum cascade laser

    NASA Astrophysics Data System (ADS)

    Phillips, Mark C.; Craig, Ian M.; Blake, Thomas A.

    2013-01-01

    We present experimental demonstrations using a broadly tunable external cavity quantum cascade laser (ECQCL) to perform Reflection-Absorption InfraRed Spectroscopy (RAIRS) of thin layers and residues on surfaces. The ECQCL compliance voltage was used to measure fluctuations in the ECQCL output power and improve the performance of the RAIRS measurements. Absorption spectra from self-assembled monolayers of a fluorinated alkane thiol and a thiol carboxylic acid were measured and compared with FTIR measurements. RAIRS spectra of the explosive compounds PETN, RDX, and tetryl deposited on gold substrates were also measured. Rapid measurement times and low noise were demonstrated, with <1E-3 absorbance noise for a 10 second measurement time.

  3. Mid-infrared gas absorption sensor based on a broadband external cavity quantum cascade laser

    NASA Astrophysics Data System (ADS)

    Sun, Juan; Deng, Hao; Liu, Ningwu; Wang, Hongliang; Yu, Benli; Li, Jingsong

    2016-12-01

    We developed a laser absorption sensor based on a pulsed, broadband tunable external cavity quantum cascade laser (ECQCL) centered at 1285 cm-1. Unlike traditional infrared spectroscopy system, a quartz crystal tuning fork (QCTF) as a light detector was used for laser signal detection. Fast Fourier transform was applied to extract vibration intensity information of QCTF. The sensor system is successfully tested on nitrous oxide (N2O) spectroscopy measurements and compared with a standard infrared detector. The wide wavelength tunability of ECQCL will allow us to access the fundamental vibrational bands of many chemical agents, which are well-suited for trace explosive, chemical warfare agent, and toxic industrial chemical detection and spectroscopic analysis.

  4. Frequency and Intensity Stabilization of Planar Waveguide-External Cavity Lasers

    NASA Astrophysics Data System (ADS)

    Tellez, Gregorio; Shoen, Steven; Quetschke, Volker

    2012-02-01

    Planar Waveguide External Cavity Lasers (PW-ECL) show an immense potential for use in precision measurement tasks and space missions because of its compactness and simple design. We show the techniques used to frequency and intensity stabilize a PW-ECL 1550nm laser system with the goal of achieving a frequency stability of 30 Hz/sqrt(Hz) and a RIN of less than 10-6. These PW-ECL systems are a potential replacement for Non-Planar Ring Oscillator (NPRO) laser systems, which have become a standard for low-noise interferometric applications, if the PW-ECL can meet the required stability. We present the initial experimental results of the intensity and frequency stabilization setup and we show a comparison between PW-ECL lasers and NPRO lasers with respect to measurements and applications requiring a high frequency and intensity stability.

  5. Low noise planar external cavity laser for interferometric fiber optic sensors

    NASA Astrophysics Data System (ADS)

    Alalusi, Mazin; Brasil, Paul; Lee, Sanggeon; Mols, Peter; Stolpner, Lew; Mehnert, Axel; Li, Steve

    2009-05-01

    A 1550 nm DWDM planar external cavity laser (ECL) is demonstrated to provide low phase/frequency noise, narrow linewidth, and low RIN. The cavity includes a semiconductor gain chip and a planar lightwave circuit waveguide with Bragg grating, packaged in a 14-pin butterfly package. This planar ECL laser is designed to operate under vibration and in harsh environmental conditions. The laser shows linewidth <= 2.6 kHz, phase/frequency noise comparable with that of long cavity fiber lasers, RIN <= -147dB/Hz at 1kHz, and power >= 10mW. Performance is suitable for various high performance fiber optic sensing systems, including interferometric sensing in Oil and Gas, military/security and other applications, currently served mostly by costly and less reliable laser sources.

  6. Characterization of coherence-or-power selectable operation of an external-cavity semiconductor diode laser.

    PubMed

    Hyodo, Masaharu; Watanabe, Masayoshi; Kawakami, Akira; Saito, Shingo; Adachi, Masaaki

    2016-12-20

    The properties of the coherence-or-power selectable operation of an external-cavity semiconductor diode laser through the control of intracavity polarization states have been characterized in detail. In our technique, a diffraction grating and a reflector functioned as a polarization-dependent output coupler, such that the portion of light fed back to the gain medium was readily controlled by rotating the intracavity polarization axis, which resulted in the selectable operation of either a high degree of coherence or a high power for the laser output. We could continuously sweep the correlation widths over a range of approximately one order of magnitude, as well as four-fold output powers by simply rotating the intracavity half-wave plate. We also demonstrated experiments on optical phase locking, using two independent coherence-or-power selectable lasers.

  7. Performance of Planar-Waveguide External Cavity Laser for Precision Measurements

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Camp, Jordan; Krainak, Michael A.; Stolpner, Lew

    2010-01-01

    A 1542-nm planar-waveguide external cavity laser (PW-ECL) is shown to have a sufficiently low level of frequency and intensity noise to be suitable for precision measurement applications. The frequency noise and intensity noise of the PW-ECL was comparable or better than the nonplanar ring oscillator (NPRO) and fiber laser between 0.1 mHz to 100 kHz. Controllability of the PW-ECL was demonstrated by stabilizing its frequency to acetylene (13C2H2) at 10(exp -13) level of Allan deviation. The PW-ECL also has the advantage of the compactness of a standard butterfly package, low cost, and a simple design consisting of a semiconductor gain media coupled to a planar-waveguide Bragg reflector. These features would make the PW-ECL suitable for precision measurements, including compact optical frequency standards, space lidar, and space interferometry

  8. Construction and characterization of external cavity diode lasers for atomic physics.

    PubMed

    Hardman, Kyle S; Bennetts, Shayne; Debs, John E; Kuhn, Carlos C N; McDonald, Gordon D; Robins, Nick

    2014-04-24

    Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included.

  9. External cavity quantum cascade lasers with ultra rapid acousto-optic tuning

    NASA Astrophysics Data System (ADS)

    Lyakh, A.; Barron-Jimenez, R.; Dunayevskiy, I.; Go, R.; Patel, C. Kumar N.

    2015-04-01

    We report operation of tunable external cavity quantum cascade lasers with emission wavelength controlled by an acousto-optic modulator (AOM). A long-wave infrared quantum cascade laser wavelength tuned from ˜8.5 μm to ˜9.8 μm when the AOM frequency was changed from ˜41MHz to ˜49 MHz. The laser delivered over 350 mW of average power at the center of the tuning curve in a linewidth of ˜4.7 cm-1. Measured wavelength switching time between any two wavelengths within the tuning range of the QCL was less than 1 μs. Spectral measurements of infrared absorption features of Freon demonstrated a capability of obtaining complete spectral data in less than 20 μs.

  10. Long-term frequency stabilization system for external cavity diode laser based on mode boundary detection.

    PubMed

    Xu, Zhouxiang; Huang, Kaikai; Jiang, Yunfeng; Lu, Xuanhui

    2011-12-01

    We have realized a long-term frequency stabilization system for external cavity diode laser (ECDL) based on mode boundary detection method. In this system, the saturated absorption spectroscopy was used. The current and the grating of the ECDL were controlled by a computer-based feedback control system. By checking if there are mode boundaries in the spectrum, the control system determined how to adjust current to avoid mode hopping. This procedure was executed periodically to ensure the long-term stabilization of ECDL in the absence of mode hops. This diode laser system with non-antireflection coating had operated in the condition of long-term mode-hop-free stabilization for almost 400 h, which is a significant improvement of ECDL frequency stabilization system.

  11. Long-term frequency stabilization system for external cavity diode laser based on mode boundary detection

    NASA Astrophysics Data System (ADS)

    Xu, Zhouxiang; Huang, Kaikai; Jiang, Yunfeng; Lu, Xuanhui

    2011-12-01

    We have realized a long-term frequency stabilization system for external cavity diode laser (ECDL) based on mode boundary detection method. In this system, the saturated absorption spectroscopy was used. The current and the grating of the ECDL were controlled by a computer-based feedback control system. By checking if there are mode boundaries in the spectrum, the control system determined how to adjust current to avoid mode hopping. This procedure was executed periodically to ensure the long-term stabilization of ECDL in the absence of mode hops. This diode laser system with non-antireflection coating had operated in the condition of long-term mode-hop-free stabilization for almost 400 h, which is a significant improvement of ECDL frequency stabilization system.

  12. Frequency stabilization of an external cavity diode laser to molecular iodine at 657.483 nm.

    PubMed

    Fang, Hui-Mei; Wang, Shing-Chung; Shy, Jow-Tsong

    2006-05-01

    The saturation spectrum of the P(84) 5-5 transition of 127I2 at 657.483 nm is obtained with the third-harmonic demodulation method using an external cavity diode laser. The laser frequency is modulated by modulating the diode current instead of modulating the cavity length with a piezoelectric transducer (PZT). Current modulation allows a modulation frequency that is higher than PZT modulation. The signal-to-noise ratio of 1000 is better than previous results presented in the literature. The laser is frequency stabilized to the hyperfine component o of the P(84) 5-5 transition with a frequency stability of better than 10 kHz (2.2 x 10(-11) relative stability).

  13. Mode-locking external-cavity laser-diode sensor for displacement measurements of technical surfaces.

    PubMed

    Czarske, Jürgen; Möbius, Jasper; Moldenhauer, Karsten

    2005-09-01

    A novel laser sensor for position measurements of technical solid-state surfaces is proposed. An external Fabry-Perot laser cavity is assembled by use of an antireflection-coated laser diode together with the technical surface. Mode locking results from pumping the laser diode synchronously to the mode spacing of the cavity. The laser cavity length, i.e., the distance to the measurement object, is determined by evaluation of the modulation transfer function of the cavity by means of a phase-locked loop. The mode-locking external-cavity laser sensor incorporates a resonance effect that results in highly resolving position and displacement measurements. More than a factor-of-10 higher resolution than with conventional nonresonant sensing principles is achieved. Results of the displacement measurements of various technical surfaces are reported. Experimental and theoretical investigations are in good agreement.

  14. Scaling the spectral beam combining channel by multiple diode laser stacks in an external cavity

    NASA Astrophysics Data System (ADS)

    Meng, Huicheng; Ruan, Xu; Du, Weichuan; Wang, Zhao; Lei, Fuchuan; Yu, Junhong; Tan, Hao

    2017-04-01

    Spectral beam combining of a broad area diode laser is a promising technique for direct diode laser applications. We present an experimental study of three mini-bar stacks in an external cavity on spectral beam combining in conjunction with spatial beam combining. At the pump current of 70 A, a CW output power of 579 W, spectral bandwidth of 18.8 nm and electro-optical conversion efficiency of 47% are achieved. The measured M 2 values of spectral beam combining are 18.4 and 14.7 for the fast and the slow axis, respectively. The brightness of the spectral beam combining output is 232 MW · cm-2 · sr-1.

  15. Influence of grating parameters on the linewidths of external-cavity diode lasers.

    PubMed

    Loh, Huanqian; Lin, Yu-Ju; Teper, Igor; Cetina, Marko; Simon, Jonathan; Thompson, James K; Vuletić, Vladan

    2006-12-20

    We investigate experimentally the influence of the grating reflectivity, grating resolution, and diode facet antireflection (AR) coating on the intrinsic linewidth of an external-cavity diode laser built with a diffraction grating in a Littrow configuration. Grating lasers at 399, 780, and 852 nm are determined to have typical linewidths between 250 and 600 kHz from measurements of their frequency noise power spectral densities. The linewidths are little affected by the presence of an AR coating on the diode facet but narrow as the grating reflectivity and grating resolution are increased, with the resolution exerting a greater effect. We also use frequency noise measurements to characterize a laser mount with improved mechanical stability.

  16. High-power operation of coherently coupled tapered laser diodes in an external cavity

    NASA Astrophysics Data System (ADS)

    Schimmel, G.; Doyen, I.; Janicot, S.; Hanna, M.; Georges, P.; Lucas-Leclin, G.; Decker, J.; Crump, P.; Erbert, G.; Kaunga-Nyirenda, S.; Moss, D.; Bull, S.; Larkins, E. C.; Witte, U.; Traub, M.

    2016-03-01

    We demonstrate a rear-side phase-locking architecture with two high-brightness diode lasers. This technique is based on the passive phase-locking of emitters in an external cavity on their rear facet, and their coherent combination on the front facet. Two high-brightness high-power tapered laser diodes are coherently combined using a Michelson-based cavity. The combining efficiency is above 80% and results in an output power of 6.7 W in a nearly diffraction-limited beam. The rear-side architecture is then used with a laser bar of 5 tapered emitters using an interferometric extended cavity, based on a diffractive optical element. We describe the experimental evaluation of the diffractive optical element, and the phase-locked operation of the laser bar.

  17. Modulation-free optical locking of an external-cavity diode laser to a filter cavity.

    PubMed

    Hayasaka, Kazuhiro

    2011-06-15

    Optical locking to a filter cavity is an effective method to eliminate the limitations of an external-cavity diode laser, such as broad spontaneous emission backgrounds and frequency jitters. Stable operation of the optical locking requires simultaneous control of the feedback phase and the diode-laser frequency. Frequency dither is usually used to extract the two error signals, but this causes extra frequency modulation in the output beam. A modulation-free method for deriving the error signals by modulating the laser-cavity coupling strength is demonstrated with a violet diode laser. A modulation-free linewidth upper limit of about 7 kHz for a 1 s measurement is realized by the method.

  18. Frequency stabilization of an external-cavity diode laser to metastable argon atoms in a discharge.

    PubMed

    Douglas, P; Maher-McWilliams, C; Barker, P F

    2012-06-01

    A laser stabilization scheme using magnetic dichroism in a RF plasma discharge is presented. This method has been used to provide a frequency stable external-cavity diode laser that is locked to the 4s[3/2](2) → 4p[5/2](3) argon laser cooling transition at 811.53 nm. Using saturated absorption spectroscopy, we lock the laser to a Doppler free peak which gave a locking range of 20 MHz when the slope of the error signal was maximized. The stability of the laser was characterized by determining the square root Allan variance of laser frequency fluctuations when the laser was locked. A stability of 129 kHz was measured at 1 s averaging time for data acquired over 6000 s.

  19. High-brightness spectral beam combining of diode laser array stack in an external cavity.

    PubMed

    Meng, Huicheng; Sun, Tangyou; Tan, Hao; Yu, Junhong; Du, Weichuan; Tian, Fei; Li, Jianming; Gao, Songxing; Wang, Xiaojun; Wu, Deyong

    2015-08-24

    We demonstrate the spectral beam combining of a diode laser stack, which contains three 970nm Mini-Bars along the fast-axis direction, in an external cavity. At the pump current of 60 A, the output power of 127 W, the spectral bandwidth of 12 nm and the Electro-optical conversion efficiency of 48.35% are achieved. The measured beam qualities after the spectral beam combining are M(2) ≈10.2 along the slow axis and M(2) ≈11.5 along the fast axis. Under a maximum injection current of 75A, the laser output power of more than 159W is achieved. The beam quality deteriorated slightly with the rising of the current from 60A to 75A, but it is enough to be coupled into a 50µm core / 0.22NA fiber.

  20. Mode-locking external-cavity laser-diode sensor for displacement measurements of technical surfaces

    SciTech Connect

    Czarske, Juergen; Moebius, Jasper; Moldenhauer, Karsten

    2005-09-01

    A novel laser sensor for position measurements of technical solid-state surfaces is proposed. An external Fabry-Perot laser cavity is assembled by use of an antireflection-coated laser diode together with the technical surface. Mode locking results from pumping the laser diode synchronously to the mode spacing of the cavity. The laser cavity length, i.e., the distance to the measurement object, is determined by evaluation of the modulation transfer function of the cavity by means of a phase-locked loop. The mode-locking external-cavity laser sensor incorporates a resonance effect that results in highly resolving position and displacement measurements. More than a factor-of-10 higher resolution than with conventional nonresonant sensing principles is achieved. Results of the displacement measurements of various technical surfaces are reported. Experimental and theoretical investigations are in good agreement.

  1. Compact MEMS external cavity tunable laser with ultra-narrow linewidth for coherent detection.

    PubMed

    Zhang, Di; Zhao, Jianyi; Yang, Qi; Liu, Wen; Fu, Yanfeng; Li, Chao; Luo, Ming; Hu, Shenglei; Hu, Qianggao; Wang, Lei

    2012-08-27

    A compact and ultra-narrow linewidth tunable laser with an external cavity based on a simple single-axis-MEMS mirror is presented in this paper. We discuss the simulation of this tunable laser using a two-step hybrid analysis method to obtain an optimal design of the device. A wide wavelength tuning range about 40 nm in C-band with a narrow linewidth of less than 50 kHz and wavelength accuracy of ± 1 GHz over the entire tuning range can be achieved experimentally. We also conduct several experiments under different conditions to test the tunable laser. This device shows an excellent performance in both single-carrier polarization-multiplexed quadrature phase-shift keying (PM-QPSK) and multi-carrier orthogonal frequency division multiplexing (OFDM) coherent systems.

  2. Construction and Characterization of External Cavity Diode Lasers for Atomic Physics

    PubMed Central

    Hardman, Kyle S.; Bennetts, Shayne; Debs, John E.; Kuhn, Carlos C. N.; McDonald, Gordon D.; Robins, Nick

    2014-01-01

    Since their development in the late 1980s, cheap, reliable external cavity diode lasers (ECDLs) have replaced complex and expensive traditional dye and Titanium Sapphire lasers as the workhorse laser of atomic physics labs1,2. Their versatility and prolific use throughout atomic physics in applications such as absorption spectroscopy and laser cooling1,2 makes it imperative for incoming students to gain a firm practical understanding of these lasers. This publication builds upon the seminal work by Wieman3, updating components, and providing a video tutorial. The setup, frequency locking and performance characterization of an ECDL will be described. Discussion of component selection and proper mounting of both diodes and gratings, the factors affecting mode selection within the cavity, proper alignment for optimal external feedback, optics setup for coarse and fine frequency sensitive measurements, a brief overview of laser locking techniques, and laser linewidth measurements are included. PMID:24796259

  3. Dual beam photoacoustic infrared spectroscopy of solids using an external cavity quantum cascade laser

    NASA Astrophysics Data System (ADS)

    Dehghany, M.; Michaelian, K. H.

    2012-06-01

    Quantum cascade laser-based instrumentation for dual beam photoacoustic (PA) spectroscopy is described in this article. Experimental equipment includes a 4.55 μm (2141-2265 cm-1) continuous wave external cavity quantum cascade laser (EC-QCL), two gas-microphone PA cells, and two lock-in amplifiers. Correction for the time and wavenumber dependence of the laser output is effected through real-time division of the PA signals derived from the sample and reference channels. Source-compensated mid-infrared absorption spectra of carbon black powder and aromatic hydrocarbon solids were obtained to confirm the reliability of the method. Absorption maxima in the EC-QCL PA spectra of hydrocarbons are better defined than those in Fourier transform infrared spectra acquired under similar conditions, enabling the detection of several previously unknown bands.

  4. Reflection-Absorption Infrared Spectroscopy of Thin Films Using an External Cavity Quantum Cascade Laser

    SciTech Connect

    Phillips, Mark C.; Craig, Ian M.; Blake, Thomas A.

    2013-02-04

    We present experimental demonstrations using a broadly tunable external cavity quantum cascade laser (ECQCL) to perform Reflection-Absorption InfraRed Spectroscopy (RAIRS) of thin layers and residues on surfaces. The ECQCL compliance voltage was used to measure fluctuations in the ECQCL output power and improve the performance of the RAIRS measurements. Absorption spectra from self-assembled monolayers of a fluorinated alkane thiol and a thiol carboxylic acid were measured and compared with FTIR measurements. RAIRS spectra of the explosive compounds PETN, RDX, and tetryl deposited on gold substrates were also measured. Rapid measurement times and low noise were demonstrated, with < 1E-3 absorbance noise for a 10 second measurement time.

  5. Broadband external cavity tunable quantum dot lasers with low injection current density.

    PubMed

    Lv, X Q; Jin, P; Wang, W Y; Wang, Z G

    2010-04-26

    Broadband grating-coupled external cavity laser, based on InAs/GaAs quantum dots, is achieved. The device has a wavelength tuning range from 1141.6 nm to 1251.7 nm under a low continuous-wave injection current density (458 A/cm(2)). The tunable bandwidth covers consecutively the light emissions from both the ground state and the 1st excited state of quantum dots. The effects of cavity length and antireflection facet coating on device performance are studied. It is shown that antireflection facet coating expands the tuning bandwidth up to ~150 nm, accompanied by an evident increase in threshold current density, which is attributed to the reduced interaction between the light field and the quantum dots in the active region of the device.

  6. External cavity-quantum cascade laser (EC-QCL) spectroscopy for protein analysis in bovine milk.

    PubMed

    Kuligowski, Julia; Schwaighofer, Andreas; Alcaráz, Mirta Raquel; Quintás, Guillermo; Mayer, Helmut; Vento, Máximo; Lendl, Bernhard

    2017-04-22

    The analytical determination of bovine milk proteins is important in food and non-food industrial applications and yet, rather labour-intensive wet-chemical, low-throughput methods have been employed since decades. This work proposes the use of external cavity-quantum cascade laser (EC-QCL) spectroscopy for the simultaneous quantification of the most abundant bovine milk proteins and the total protein content based on the chemical information contained in mid-infrared (IR) spectral features of the amide I band. Mid-IR spectra of protein standard mixtures were used for building partial least squares (PLS) regression models. Protein concentrations in commercial bovine milk samples were calculated after chemometric compensation of the matrix contribution employing science-based calibration (SBC) without sample pre-processing. The use of EC-QCL spectroscopy together with advanced multivariate data analysis allowed the determination of casein, α-lactalbumin, β-lactoglobulin and total protein content within several minutes.

  7. Widely tunable, narrow linewidth external-cavity gain chip laser for spectroscopy between 10 - 11 µm

    NASA Astrophysics Data System (ADS)

    Shin, Dong K.; Henson, Bryce M.; Khakimov, Roman I.; Ross, Jacob A.; Dedman, Colin J.; Hodgman, Sean S.; Baldwin, Kenneth G. H.; Truscott, Andrew G.

    2016-11-01

    We have developed and characterised a stable, narrow linewidth external-cavity laser (ECL) tunable over 100 nm around 1080 nm, using a single-angled-facet gain chip. We propose the ECL as a low-cost, high-performance alternative to fibre and diode lasers in this wavelength range and demonstrate its capability through the spectroscopy of metastable helium. Within the coarse tuning range, the wavelength can be continuously tuned over 30 pm (7.8 GHz) without mode-hopping and modulated with bandwidths up to 3 kHz (piezo) and 37(3) kHz (current). The spectral linewidth of the free-running ECL was measured to be 22(2) kHz (Gaussian) and 4.2(3) kHz (Lorentzian) over 22.5 ms, while a long-term frequency stability better than 40(20) kHz over 11 hours was observed when locked to an atomic reference.

  8. Piezo activated mode tracking system for widely tunable mode-hop-free external cavity mid-IR semiconductor lasers

    NASA Technical Reports Server (NTRS)

    Wysocki, Gerard (Inventor); Tittel, Frank K. (Inventor); Curl, Robert F. (Inventor)

    2010-01-01

    A widely tunable, mode-hop-free semiconductor laser operating in the mid-IR comprises a QCL laser chip having an effective QCL cavity length, a diffraction grating defining a grating angle and an external cavity length with respect to said chip, and means for controlling the QCL cavity length, the external cavity length, and the grating angle. The laser of claim 1 wherein said chip may be tuned over a range of frequencies even in the absence of an anti-reflective coating. The diffraction grating is controllably pivotable and translatable relative to said chip and the effective QCL cavity length can be adjusted by varying the injection current to the chip. The laser can be used for high resolution spectroscopic applications and multi species trace-gas detection. Mode-hopping is avoided by controlling the effective QCL cavity length, the external cavity length, and the grating angle so as to replicate a virtual pivot point.

  9. Broadly tunable high-power InAs/GaAs quantum-dot external cavity diode lasers.

    PubMed

    Fedorova, Ksenia A; Cataluna, Maria Ana; Krestnikov, Igor; Livshits, Daniil; Rafailov, Edik U

    2010-08-30

    A record broadly tunable high-power external cavity InAs/GaAs quantum-dot diode laser with a tuning range of 202 nm (1122 nm-1324 nm) is demonstrated. A maximum output power of 480 mW and a side-mode suppression ratio greater than 45 dB are achieved in the central part of the tuning range. We exploit a number of strategies for enhancing the tuning range of external cavity quantum-dot lasers. Different waveguide designs, laser configurations and operation conditions (pump current and temperature) are investigated for optimization of output power and tunability.

  10. Antireflection-coated blue GaN laser diodes in an external cavity and Doppler-free indium absorption spectroscopy.

    PubMed

    Hildebrandt, Lars; Knispel, Richard; Stry, Sandra; Sacher, Joachim R; Schael, Frank

    2003-04-20

    Commercially available GaN-based laser diodes were antireflection coated in our laboratory and operated in an external cavity in a Littrow configuration. A total tuning range of typically 4 nm and an optical output power of up to 30 mW were observed after optimization of the external cavity. The linewidth was measured with a beterodyne technique, and 0.8 MHz at a sweep time of 50 ms was obtained. The mode-hop-free tuning range was more than 50 GHz. We demonstrated the performance of the laser by detecting the saturated absorption spectrum of atomic indium at 410 nm, allowing observation of well-resolved Lamb dips.

  11. High-order external cavity modes and restabilization of a laser diode subject to a phase-conjugate feedback.

    PubMed

    Mercier, Émeric; Weicker, Lionel; Wolfersberger, Delphine; Kane, Deborah M; Sciamanna, Marc

    2017-01-15

    We experimentally report the sequence of bifurcations destabilizing and restabilizing a laser diode with phase-conjugate feedback when the feedback rate is increased. Specifically, we successively observe the initial steady state, undamped relaxation oscillations, quasi-periodicity, chaos, and oscillating solutions at harmonics up to 13 times the external cavity frequency but also the restabilization to a steady state. The experimental results are qualitatively well reproduced by a model that accounts for the time the light takes to penetrate the phase-conjugate mirror. The theory points out that the system restabilizes through a Hopf bifurcation whose frequency is a harmonic of the external cavity frequency.

  12. C-band external-cavity wavelength-tunable laser based on a liquid-crystal deflector.

    PubMed

    Wang, P; Seah, L K; Murukeshan, V M; Chao, Z X; Yin, X J

    2007-08-10

    A novel C-band external-cavity wavelength-tunable laser is proposed. The laser consists of a semiconductor gain chip, a collimating lens, a fixed etalon, a liquid-crystal deflector and a diffraction grating in a Littrow configuration. The lasing wavelength of this tunable external-cavity laser can be tuned to 19 wavelength channels of 100 GHz spacing. All channels are within 2.5 GHz of the ITU grids with a side-mode suppression ratio of approximately 35 dB over the whole range.

  13. On the importance of cavity-length and heat dissipation in GaN-based vertical-cavity surface-emitting lasers

    NASA Astrophysics Data System (ADS)

    Liu, W. J.; Hu, X. L.; Ying, L. Y.; Chen, S. Q.; Zhang, J. Y.; Akiyama, H.; Cai, Z. P.; Zhang, B. P.

    2015-04-01

    Cavity-length dependence of the property of optically pumped GaN-based vertical-cavity surface-emitting lasers (VCSELs) with two dielectric distributed Bragg reflectors was investigated. The cavity lengths were well controlled by employing etching with inductively coupled plasma and chemical mechanical polishing. It was found that the lasing characteristics including threshold, slope efficiency and spontaneous emission coupling factor were substantially improved with reducing the cavity length. In comparison with the device pumped by a 400 nm pulsed laser, the lasing spectrum was featured by a red shift and simultaneous broadening with increasing the pumping energy of a 355 nm pulsed laser. Moreover, the lasing threshold was much higher when pumped by a 355 nm pulsed laser. These were explained by taking into account of the significant heating effect under 355 nm pumping. Our results demonstrate that a short cavity length and good heat-dissipation are essential to GaN-based VCSELs.

  14. Surface-emitting vertical cavity with vapor-grown single crystal of cyano-substituted thiophene/phenylene co-oligomer

    NASA Astrophysics Data System (ADS)

    Hatano, Ryota; Goto, Kaname; Yamashita, Kenichi; Sasaki, Fumio; Yanagi, Hisao

    2017-04-01

    Photoluminescence from an organic microcavity is investigated using vapor-grown single crystals of 5,5‧-bis(4‧-cyano-biphenyl-4-yl)-2,2‧-bithiophene (BP2T-CN). A vertical half-cavity structure is fabricated with thin platelet crystals of BP2T-CN placed on a distributed Bragg reflector (DBR). Lying orientation of the BP2T-CN molecules is suitable for effective surface emission from the cavity. Angle-resolved photoluminescence spectra show anticrossing splits, suggesting the formation of cavity polaritons induced by coupling between confined photons and excitons. Phenomenological analysis well reproduces the dispersion characteristics with a Rabi splitting energy of 90 meV at room temperature. With increasing excitation fluence under optical pumping, one of the cavity photon modes is gain-narrowed, and amplified emission is obtained from the surface-emitting half-cavity structure.

  15. Low-threshold lasing of InGaN vertical-cavity surface-emitting lasers with dielectric distributed Bragg reflectors

    NASA Astrophysics Data System (ADS)

    Tawara, Takehiko; Gotoh, Hideki; Akasaka, Tetsuya; Kobayashi, Naoki; Saitoh, Tadashi

    2003-08-01

    Lasing action is achieved in InGaN vertical-cavity surface-emitting lasers (VCSELs) with dielectric distributed Bragg reflectors (DBRs). We fabricated III-nitride VCSELs by removing a SiC substrate from a III-nitride cavity with a dry etching technique and then wafer bonding the cavity and SiO2/ZrO2 DBRs. These VCSELs have a high quality factor of 460 and a spontaneous emission factor of 10-2. We observed lasing at a wavelength of 401 nm at room temperature with optical pumping. This lasing action was demonstrated at a low threshold of 5.1 mJ/cm2 by using a high-quality crystalline cavity and quantum-well layers without surface roughening or cracking.

  16. Frequency characterization of a swept- and fixed-wavelength external-cavity quantum cascade laser by use of a frequency comb.

    PubMed

    Knabe, Kevin; Williams, Paul A; Giorgetta, Fabrizio R; Armacost, Chris M; Crivello, Sam; Radunsky, Michael B; Newbury, Nathan R

    2012-05-21

    The instantaneous optical frequency of an external-cavity quantum cascade laser (QCL) is characterized by comparison to a near-infrared frequency comb. Fluctuations in the instantaneous optical frequency are analyzed to determine the frequency-noise power spectral density for the external-cavity QCL both during fixed-wavelength and swept-wavelength operation. The noise performance of a near-infrared external-cavity diode laser is measured for comparison. In addition to providing basic frequency metrology of external-cavity QCLs, this comb-calibrated swept QCL system can be applied to rapid, precise broadband spectroscopy in the mid-infrared spectral region.

  17. Graphene surface emitting terahertz laser: Diffusion pumping concept

    SciTech Connect

    Davoyan, Arthur R.; Morozov, Mikhail Yu.; Popov, Vyacheslav V.; Satou, Akira; Otsuji, Taiichi

    2013-12-16

    We suggest a concept of a tunable graphene-based terahertz (THz) surface emitting laser with diffusion pumping. We employ significant difference in the electronic energy gap of graphene and a typical wide-gap semiconductor, and demonstrate that carriers generated in the semiconductor can be efficiently captured by graphene resulting in population inversion and corresponding THz lasing from graphene. We develop design principles for such a laser and estimate its performance. We predict up to 50 W/cm{sup 2} terahertz power output for 100 kW/cm{sup 2} pump power at frequency around 10 THz at room temperature.

  18. High performance surface-emitting lasers with dry etched facets

    NASA Astrophysics Data System (ADS)

    Ou, S. S.; Jansen, M.; Yang, J. J.; Sergant, M.; Mawst, L. J.; Botez, D.; Roth, T. J.; Hess, C.; Tu, C.

    1992-12-01

    The fabrication, performance characteristics, and applications of monolithic in-plane surface-emitting lasers (IPSELs) with dry-etched 45-degree micromirrors are reviewed. Several types of such laser diode structures in both junction-up and junction-down configurations are considered. The performance goals for IPSELs with 45-degree micromirrors are high power and efficiency, high duty cycle and CW operation, good reliability, and high fabrication yields. The proposed approach for achieving these goals includes uniform quantum well material growth and dry etching of the laser micromirrors with tight fabrication tolerances.

  19. Spectral dynamics of picosecond gain-switched pulses from nitride-based vertical-cavity surface-emitting lasers

    PubMed Central

    Chen, Shaoqiang; Ito, Takashi; Asahara, Akifumi; Yoshita, Masahiro; Liu, Wenjie; Zhang, Jiangyong; Zhang, Baoping; Suemoto, Tohru; Akiyama, Hidefumi

    2014-01-01

    Short pulses generated from low-cost semiconductor lasers by a simple gain-switching technique have attracted enormous attention because of their potential usage in wide applications. Therein, reducing the durations of gain-switched pulses is a key technical point for promoting their applications. Therefore, understanding the dynamic characteristics of gain-switched pulses is highly desirable. Herein, we used streak camera to investigate the time- and spectral-resolved lasing characteristics of gain-switched pulses from optically pumped InGaN single-mode vertical-cavity surface-emitting lasers. We found that fast initial components with ultra-short durations far below our temporal resolution of 5.5 ps emerged on short-wavelength sides, while the entire pulses were down-chirped, resulting in the simultaneous broadening of the spectrum and pulse width. The measured chirp characteristics were quantitatively explained using a single-mode rate-equation model, combined with carrier-density-dependent gain and index models. The observed universal fast short-wavelength components can be useful in generating even shorter pulses from gain-switched semiconductor lasers. PMID:24710268

  20. Submonolayer Quantum Dots for High Speed Surface Emitting Lasers

    PubMed Central

    2007-01-01

    We report on progress in growth and applications of submonolayer (SML) quantum dots (QDs) in high-speed vertical-cavity surface-emitting lasers (VCSELs). SML deposition enables controlled formation of high density QD arrays with good size and shape uniformity. Further increase in excitonic absorption and gain is possible with vertical stacking of SML QDs using ultrathin spacer layers. Vertically correlated, tilted or anticorrelated arrangements of the SML islands are realized and allow QD strain and wavefunction engineering. Respectively, both TE and TM polarizations of the luminescence can be achieved in the edge-emission using the same constituting materials. SML QDs provide ultrahigh modal gain, reduced temperature depletion and gain saturation effects when used in active media in laser diodes. Temperature robustness up to 100 °C for 0.98 μm range vertical-cavity surface-emitting lasers (VCSELs) is realized in the continuous wave regime. An open eye 20 Gb/s operation with bit error rates better than 10−12has been achieved in a temperature range 25–85 °Cwithout current adjustment. Relaxation oscillations up to ∼30 GHz have been realized indicating feasibility of 40 Gb/s signal transmission. PMID:21794188

  1. Absorption and wavelength modulation spectroscopy of NO2 using a tunable, external cavity continuous wave quantum cascade laser.

    PubMed

    Karpf, Andreas; Rao, Gottipaty N

    2009-01-10

    The absorption spectra and wavelength modulation spectroscopy (WMS) of NO(2) using a tunable, external cavity CW quantum cascade laser operating at room temperature in the region of 1625 to 1645 cm(-1) are reported. The external cavity quantum cascade laser enabled us to record continuous absorption spectra of low concentrations of NO(2) over a broad range (approximately 16 cm(-1)), demonstrating the potential for simultaneously recording the complex spectra of multiple species. This capability allows the identification of a particular species of interest with high sensitivity and selectivity. The measured spectra are in excellent agreement with the spectra from the high-resolution transmission molecular absorption database [J. Quant. Spectrosc. Radiat. Transfer 96, 139-204 (2005)]. We also conduct WMS for the first time using an external cavity quantum cascade laser, a technique that enhances the sensitivity of detection. By employing WMS, we could detect low-intensity absorption lines, which are not visible in the simple absorption spectra, and demonstrate a minimum detection limit at the 100 ppb level with a short-path absorption cell. Details of the tunable, external cavity quantum cascade laser system and its performance are discussed.

  2. Use of external cavity quantum cascade laser compliance voltage in real-time trace gas sensing of multiple chemicals

    SciTech Connect

    Phillips, Mark C.; Taubman, Matthew S.; Kriesel, Jason M.

    2015-02-08

    We describe a prototype trace gas sensor designed for real-time detection of multiple chemicals. The sensor uses an external cavity quantum cascade laser (ECQCL) swept over its tuning range of 940-1075 cm-1 (9.30-10.7 µm) at a 10 Hz repetition rate.

  3. Communications: fiber-coupled external cavity semiconductor laser. Annual summary report 1 Jul 80-30 Jun 81

    SciTech Connect

    Rediker, R.H.

    1981-07-01

    The series combination of a semiconductor-diode gain element (a diode laser whose end facets have been antireflection coated) and an optical fiber has been placed inside an external cavity and the external cavity has lased in a single spectral line whose width was less than the 1.7 x 10 to the -5-nm resolution of the scanning Fabry-Perot interferometer used. When a grating in the Littrow configuration is used as one of the cavity end reflectors the spectral line can be tuned. Other elements such as a polarizer can also be placed inside the cavity to select a desired mode of operation. The addition of elements inside the external cavity (including the optical fiber) introduces loss which increases both the threshold current for laser operation and the ratio of power at the gain element facet to cavity output power. With optimized design the long mean life of the semiconductor laser can be maintained by reducing the output power per gain element by less than 33 percent. In terms of the overall goal of this program, The Fiber-Coupled External Cavity Semiconductor Laser, the results obtained are extremely encouraging.

  4. A new optically pumped tandem magnetometer: principles and experiences

    NASA Astrophysics Data System (ADS)

    Pulz, E.; Jäckel, K.-H.; Linthe, H.-J.

    1999-11-01

    In this paper we describe a new design for an optically pumped tandem magnetometer situated at the GeoForschungsZentrum Potsdam. A tandem magnetometer combines the fast response of a self-oscillating vapour magnetometer with the accuracy of a narrow line Mz-type magnetometer. A newly patented method of coupling the two sensors avoids any stray magnetic fields and so allows a compact design of the instrument itself, as well as facilitating its operation in close proximity to other magnetometers. A prototype Cs-K tandem magnetometer for use in magnetic observatories is described. We then show typical results of a long-term comparison with both a second type of optically pumped magnetometer and an Overhauser proton magnetometer. Finally, a resuméis given of four years of continuous operation of this new type of magnetometer with respect to the data quality produced and its operational reliability.

  5. Method and apparatus for efficient operation of optically pumped laser

    NASA Technical Reports Server (NTRS)

    Sipes, Jr., Donald L. (Inventor)

    1987-01-01

    An optically pumped single mode laser, e.g., Nd:YAG crystal (20) with planoconcave mirrors is increased in efficiency by an order of magnitude to about 8% by optics (25, 27) for focusing the high power multimode output of laser diode arrays (21, 22) into the mode volume (20') of the laser medium (20). A plurality of these optically pumped single mode lasers (1-4) may be cascaded in a ring with dichroic mirrors (M.sub.1 -M.sub.4) at the corners for coupling in the laser diode arrays, each having its own means for spatially tailoring its beam to concentrate pump distribution inside the lasing mode volume of the medium. An InGaAlAs pump diode (30) with its wavelength the same as the lasing medium makes the ring unidirectional.

  6. Plasma channel optical-pumping device and method

    SciTech Connect

    Judd, O.P.

    1981-07-17

    A device and method are described for optically pumping a gaseous laser using blackbody radiation produced by a plasma channel which is formed from an electrical discharge between two electrodes spaced at opposite longitudinal ends of the laser. A preionization device which can comprise a laser or electron beam accelerator produces a preionization beam which is sufficient to cause an elctrical discharge between the electrodes to initiate the plasma channel along the preionization path. The optical pumping energy is supplied by a high voltage power supply rather than by the preionization beam. High output optical intensities are produced by the laser due to the high temperature black-body radiation produced by the plasma channel, in the same manner as an exploding wire type laser. However, unlike the exploding wire type laser, the disclosed invention can be operated in a repetitive manner by utilizing a repetitive pulsed preionization device.

  7. Erbium Doped GaN Lasers by Optical Pumping

    DTIC Science & Technology

    2016-07-13

    P.O. Box 12211 Research Triangle Park, NC 27709-2211 Er doped GaN, gain medium, high energy laser, optical pump REPORT DOCUMENTATION PAGE 11. SPONSOR...Nanophotonics Center, Texas Tech University Lubbock, TX 79409-3102 jingyu.lin@ttu.edu; hx.jiang@ttu.edu I. Summary of Progress High energy and...emerging technologies. The optical gain medium is the heart of a high energy laser (HEL) system. Comparing with the presently dominant gain material

  8. Microfabricated Optically-Pumped Magnetometers for Biomagnetic Applications

    NASA Astrophysics Data System (ADS)

    Knappe, Svenja; Alem, Orang; Sheng, Dong; Kitching, John

    2016-06-01

    We report on the progress in developing microfabricated optically-pumped magnetometer arrays for imaging applications. We have improved our sensitivities by several orders of magnitude in the last ten years. Now, our zero-field magnetometers reach noise values below 15 fT/Hz1/2. Recently, we have also developed gradiometers to reject ambient magnetic field noise. We have built several imaging arrays and validated them for biomedical measurements of brain and heart activity.

  9. Stimulated IR emission in an optically pumped cesium vapour

    SciTech Connect

    Sitnikov, M G; Znamenskiy, Nikolay V; Manykin, Eduard A; Petrenko, Evgenii A; Grigoryan, Grigorii G

    2000-03-31

    It is demonstrated that the optical pumping of a Cs vapour with light pulses of a dye laser tunable within the range of 15390-17920 cm{sup -1} gives rise to high-power stimulated IR emission on several atomic transitions. Analysis of threshold, energy, and spectral characteristics of this emission allowed the mechanism underlying this effect to be explained. (active media. lasers)

  10. Circularly Symmetric, Distributed-Feedback Structures for Surface-Emitting Semiconductor Lasers.

    NASA Astrophysics Data System (ADS)

    Erdogan, Turan

    1992-01-01

    This thesis explores a fundamentally unique, two -dimensional optical resonator which confines the propagation of circular waves through a distributed-feedback (DFB) process. In addition to an investigation of the unique physics associated with the interaction of circular waves with radially periodic structures, a theoretical and experimental analysis of a novel, circularly symmetric surface-emitting semiconductor laser is carried out. The intent of this analysis is to show that it is possible for a semiconductor laser to directly produce low-divergence, spectrally narrow emission that is circularly symmetric in cross-section. Such emission requires lasing in a single radial and azimuthal mode in a resonator that is much larger than an optical wavelength in two dimensions. A coupled-amplitude theory is developed that describes the coupling of both cylindrical waves and circular guided modes along the radial direction. The angular nature of propagation is characterized by a discrete set of azimuthal modes, which remain uncoupled in a circularly symmetric periodic structure. The theory is applied to the classical problem of a radiating source surrounded by a circular, periodic structure. It is found that a substantial region near the center of the structure can exist, wherein the spontaneous emission from sources at all possible locations is either strongly enhanced or inhibited. Furthermore, the theory is applied to the problem of a circular DFB laser. It is shown that the behavior of the modes associated with the radial direction is very similar to that of a linear DFB laser, while the modes associated with the azimuthal dimension are very densely spaced in frequency and threshold gain. The results suggest that it should be difficult to achieve lasing in a single azimuthal mode. The experimental analysis emphasizes the possibility of exciting circular modes in optically pumped semiconductor lasers. An analysis of the fabrication of concentric-circle gratings by

  11. Angle-resolved scattering spectroscopy of explosives using an external cavity quantum cascade laser

    NASA Astrophysics Data System (ADS)

    Suter, Jonathan D.; Bernacki, Bruce E.; Phillips, Mark C.

    2012-01-01

    We present a study of the spectral and angular dependence of the diffuse scatter of mid-infrared (MIR) laser light from explosives residues on surfaces. Experiments were performed using an external cavity quantum cascade laser (ECQCL) tunable between 7 and 8 μm (1270 to 1400 cm-1) for surface illumination. A mercury cadmium telluride (MCT) detector was used to detect backscattered spectra as a function of surface angle at a 2 meter standoff. A ferroelectric focal plane array was used to build hyperspectral images at a 0.5 meter standoff. Residues of RDX, tetryl, and TNT were investigated on surfaces including a painted car door for angles between zero (specular) and 50 degrees. We observe spectral signatures of the explosives in the diffuse scattering geometry which differ significantly from those observed in transmission geometries. Characterization of the scattered light spectra of explosives on surfaces will be essential for understanding the performance of standoff explosives detection instruments and developing robust spectral analysis techniques.

  12. External cavity tunable quantum cascade lasers and their applications to trace gas monitoring.

    PubMed

    Rao, Gottipaty N; Karpf, Andreas

    2011-02-01

    Since the first quantum cascade laser (QCL) was demonstrated approximately 16 years ago, we have witnessed an explosion of interesting developments in QCL technology and QCL-based trace gas sensors. QCLs operate in the mid-IR region (3-24 μm) and can directly access the rotational vibrational bands of most molecular species and, therefore, are ideally suited for trace gas detection with high specificity and sensitivity. These sensors have applications in a wide range of fields, including environmental monitoring, atmospheric chemistry, medical diagnostics, homeland security, detection of explosive compounds, and industrial process control, to name a few. Tunable external cavity (EC)-QCLs in particular offer narrow linewidths, wide ranges of tunability, and stable power outputs, which open up new possibilities for sensor development. These features allow for the simultaneous detection of multiple species and the study of large molecules, free radicals, ions, and reaction kinetics. In this article, we review the current status of EC-QCLs and sensor developments based on them and speculate on possible future developments.

  13. A low-temperature external cavity diode laser for broad wavelength tuning

    NASA Astrophysics Data System (ADS)

    Tobias, William G.; Rosenberg, Jason S.; Hutzler, Nicholas R.; Ni, Kang-Kuen

    2016-11-01

    We report on the design and characterization of a low-temperature external cavity diode laser (ECDL) system for broad wavelength tuning. The performance achieved with multiple diode models addresses the scarcity of commercial red laser diodes below 633 nm, which is a wavelength range relevant to the spectroscopy of many molecules and ions. Using a combination of multiple-stage thermoelectric cooling and water cooling, the operating temperature of a laser diode is lowered to -64 °C, more than 85 °C below the ambient temperature. The laser system integrates temperature and diffraction grating feedback tunability for coarse and fine wavelength adjustments, respectively. For two different diode models, single-mode operation is achieved with 38 mW output power at 616.8 nm and 69 mW at 622.6 nm, more than 15 nm below their ambient temperature free-running wavelengths. The ECDL design can be used for diodes of any available wavelength, allowing individual diodes to be tuned continuously over tens of nanometers and extending the wavelength coverage of commercial laser diodes.

  14. Deterministic temporal chaos from a mid-infrared external cavity quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Grillot, Frédéric; Jumpertz, Louise; Schires, Kevin; Carras, Mathieu; Sciamanna, Marc

    2016-02-01

    Quantum cascade lasers (QCLs) are unipolar semiconductor lasers offering access to wavelengths from the mid-infrared (IR) to the terahertz domain and promising impact on various applications such as free-space communications, high-resolution spectroscopy, LIDAR remote sensing or optical countermeasures. Unlike bipolar semiconductor lasers, stimulated emission in QCLs is obtained via electronic transitions between discrete energy states inside the conduction band. Recent technological progress has led to QCLs operating in pulsed or continuous wave mode, at room temperature in single- or multi-mode operation, with high powers up to a few watts for mid-IR devices. This spectacular development raises multiple interrogations on the stability of QCLs as little is known on their dynamical properties. Very recently, experiments based on optical spectrum measurements have unveiled the existence of five distinct feedback regimes without, however, identifying the complex dynamics dwelling within the QCL. In this article we provide the first experimental evidence of a route to chaos in a QCL emitting at mid-IR wavelength. When applying optical feedback with an increasing strength, the QCL dynamics bifurcate to periodic dynamics at the external cavity frequency and later to chaos without an undamping of relaxation oscillations, hence contrasting with the well-known scenarios occurring in interband laser diodes.

  15. Highly efficient second harmonic generation of a light carrying orbital angular momentum in an external cavity.

    PubMed

    Zhou, Zhi-Yuan; Li, Yan; Ding, Dong-Sheng; Zhang, Wei; Shi, Shuai; Shi, Bao-Sen; Guo, Guang-Can

    2014-09-22

    Traditional methods for generating a light carrying orbital angular momentum (OAM) include the use of holographic diffraction gratings, vortex phase plates and spatial light modulators. Here we report a new method for highly efficient second-harmonic generation (SHG) of a light with OAM. By properly aligning an external cavity that contains a quasi-phase matching nonlinear crystal and pumping it with a light carrying OAM, mode matching between the pump light and the cavity's higher order Laguerre-Gaussian (LG) mode is achieved, SHG with a conversion efficiency of up to 10.3% is obtained. We have demonstrated for the first time that the cavity can stably operate at its higher order LG mode similar to that of a Gaussian mode. The second harmonic generated light has an OAM value that is double with respected to the OAM value of the pump light. The parameters that affect the beam quality and conversion efficiency are discussed in detail. Our work opens a brand new field in laser optics and makes the first step toward high efficiency processing using a light carrying OAM.

  16. Comparison of spectral beam combining based on an external cavity with and without microlens array

    NASA Astrophysics Data System (ADS)

    Zhan, Sheng-bao; Wu, Zhuo-liang; Zhang, Jie; Wen, Jun; Liu, Quan-jin

    2016-03-01

    An experimental system of spectral beam combining based on external cavity with a microlens array has been designed and built. According to the theoretical models established, the influence of the transverse offsets on coupling efficiency and beam quality with and without a microlens array were compared. The simulation results show that the incorporation of microlens can significantly improve the coupling efficiency and beam quality. In the experiment of individual fiber laser, the fiber laser can be tunable in a range of 40.23 nm with a microlens, wider than the one without the microlens (36.25 nm). In the spectral beam combining experiment of two fiber lasers with a microlens array, the combined efficiency is 77% with the output power of 695 mW and the beam quality factor (Mx2 ) of 1.27, and for the system without the microlens array, the combining efficiency is 75% with the output power of 660 mW and the beam quality factor (Mx2) of 1.31. The experiment results show that the SBC system with a microlens array has slightly better performance than that without the microlens array, which is almost consistent with the theoretical analysis results for the fiber array width of 0-2.5 mm.

  17. A coupled optoelectronic oscillator by using an actively mode-locked external-cavity diode laser

    NASA Astrophysics Data System (ADS)

    Yoon, Tai Hyun; Lee, Jeongmin; Jang, Gwang Hoon; Yoon, Duseong; Song, Minsoo

    2009-05-01

    We propose and demonstrate a novel coupled optoelectronic oscillator consisting of an actively mode-locked external- cavity diode laser (ECDL) at 852 nm and a microwave feed-back loop. We show that the oscillation frequency can be precisely tuned by varying the feedback phase and the frequency tuning slope depends only on the reflectivity of the output coupler of the ECDL. In the proof-of-principle experiment, we found that the phase noise spectrum and frequency stability of the microwave carrier frequency at 2.298 GHz was dominated by the quality factor of the ECDL cavity, i.e., the Leeson frequency of the optical resonator. This feature could be understood since the Leeson frequency is inversely proportional to the Q- value of the feed-back resonator. Our COEO has a great potential as a compact and portable optoelectronic oscillator that generates a highly-stable microwave reference frequency, for instance, by stabilizing the repetition frequency to the hyperfine transition of Cs atoms at 9.2 GHz.

  18. Compact double optical feedback external-cavity diode laser system and its frequency stabilization

    NASA Astrophysics Data System (ADS)

    Doi, Kohei; Minabe, Yuta; Sato, Takashi; Maruyama, Takeo; Ohkawa, Masashi; Tsubokawa, Tsuneya

    2007-02-01

    External cavity diode laser (ECDL) systems are presently experiencing a surge in popularity as laser light-sources, in advanced optical communications- and measurement-systems. Because such systems require that their external reflectors be precisely controlled, to eliminate low frequency fluctuations (LFF) in optical output, we conducted experiments with a two-cavity version, which easily eliminated LFFs, as expected. The technique has the added advantage of a narrower oscillation-linewidth than would be achievable, using a single optical feedback. However, the ECDL's oscillation frequency is susceptible to the influences of the drive-current, as well as changes, both in the refractive index, and the overall length of the external reflector that results from fluctuations in atmospheric temperature. We made every effort to maintain the length of the ECDL cavity, while evaluating oscillation-frequency stability. We used a Super-Invar board as the platform for our compact ECDL system to minimize the influence of thermal expansion, because of its low expansion coefficient. We then compared the effect of atmospheric temperature variations between two experimental conditions, with the Super-invar board and without it, and finally took note of the improvement in performance, using the board.

  19. A low-temperature external cavity diode laser for broad wavelength tuning.

    PubMed

    Tobias, William G; Rosenberg, Jason S; Hutzler, Nicholas R; Ni, Kang-Kuen

    2016-11-01

    We report on the design and characterization of a low-temperature external cavity diode laser (ECDL) system for broad wavelength tuning. The performance achieved with multiple diode models addresses the scarcity of commercial red laser diodes below 633 nm, which is a wavelength range relevant to the spectroscopy of many molecules and ions. Using a combination of multiple-stage thermoelectric cooling and water cooling, the operating temperature of a laser diode is lowered to -64 °C, more than 85 °C below the ambient temperature. The laser system integrates temperature and diffraction grating feedback tunability for coarse and fine wavelength adjustments, respectively. For two different diode models, single-mode operation is achieved with 38 mW output power at 616.8 nm and 69 mW at 622.6 nm, more than 15 nm below their ambient temperature free-running wavelengths. The ECDL design can be used for diodes of any available wavelength, allowing individual diodes to be tuned continuously over tens of nanometers and extending the wavelength coverage of commercial laser diodes.

  20. Interaction of phase and amplitude shaping in an external cavity semiconductor laser

    NASA Astrophysics Data System (ADS)

    Pilny, Rouven H.; Döpke, Benjamin; Balzer, Jan C.; Brenner, Carsten; Klehr, Andreas; Erbert, Götz; Tränkle, Günther; Hofmann, Martin R.

    2016-03-01

    Ultrashort pulse generation with semiconductor lasers poses a promising alternative to currently available femtosecond laser sources like solid state and fiber lasers. Semiconductor devices can be produced inexpensively, are energy efficient and their wavelength can be designed by band gap engineering. Furthermore they feature a tunable repetition rate. Yet pulse duration and peak power of those devices limit their potential for applications so far. However, recent research demonstrated a reduction of the pulse width from 534 fs (full width half maximum) to 216 fs by shaping the spectrally resolved spectral phase and amplitude inside the cavity. The utilized system consisted of a mode-locked edge emitting semiconductor laser diode, a spatial light modulator inside the external cavity to carry out the pulse shaping and an evolutionary algorithm to optimize the phase and amplitude. Here we present the results of separate phase and amplitude shaping as well as their interaction if optimized together at the same time. Furthermore we demonstrate the flexibility of the phase and amplitude shaping with respect to each other. Thus we expect of our system to enable adaptation to a resonator external dispersion.

  1. Packaged heterodyne source modules based on external cavity lasers for microwave applications

    NASA Astrophysics Data System (ADS)

    Chuyanov, Vadim; Kupershmidt, Vladimir; Kusnadi, Frans; Plaessmann, Henry; Ozcan, Meric

    2005-03-01

    External cavity lasers (ECL) based on semiconductor diode gain elements and Fiber Bragg Gratings (FBG) have been developed for Telecom (OC-48) nd Analog (CATV, QAM) applications. They possess very narrow linewidth (100 kHz) and exceptional wavelength stability. These qualities makes them attractive platform for implementation of heterodyne sources and Optical Phase Locked Loops (OPLL) for Microwave Photonics applications. We discuss two types of such heterodyne sources: heterodyne oscillator based on heterodyning of two ECL, and fixed frequency heterodyne oscillators based on ECL with FBG written in the polarization maintaining fiber. All two types of heterodyne sources were built based on industry standard 14-pin butterfly package. All of them exhibited excellent wavelength stability (less than 1 pm/mA and 1-2 pm/°C). Fixed frequency sources provided beat oscillation around 40 GHz. We present performance characteristics and measurement data on (linewidth, phase noise, heterodyne mixing, etc.) and discuss the merits of ECL use as heterodyne sources for Microwave Photonics applications.

  2. Characterization of a swept external cavity quantum cascade laser for rapid broadband spectroscopy and sensing

    SciTech Connect

    Brumfield, Brian E.; Taubman, Matthew S.; Suter, Jonathan D.; Phillips, Mark C.

    2015-09-21

    The performance of a rapidly swept external cavity quantum cascade laser (ECQCL) system combined with an open-path Herriott cell was evaluated for time-resolved measurements of chemical species with broad and narrow absorption spectra. A spectral window spanning 1278 – 1390 cm-1 was acquired at a 200 Hz acquisition rate, corresponding to a tuning rate of 2x104 cm-1/s, with a spectral resolution of 0.2 cm-1. The capability of the ECQCL to measure < 100 ppbv changes in N2O and F134A concentrations on millisecond timescales was demonstrated in simulated plume studies with releases near the open-path Herriott cell. Absorbance spectra measured using the ECQCL system exhibited noise-equivalent absorption coefficients of 5x10-9 cm-1Hz-1/2. For a spectrum acquisition time of 5 ms, noise-equivalent concentrations (NEC) for N2O and F134A were measured to be 70 and 16 ppbv respectively, which improved to sub-ppbv levels with averaging to 100 s. Noise equivalent column densities of 0.64 and 0.25 ppmv x m in 1 sec are estimated for N2O and F134A.

  3. Modulation performance of semiconductor laser coupled with an ultra-short external cavity

    NASA Astrophysics Data System (ADS)

    Ahmed, Moustafa; Bakry, Ahmed

    2016-02-01

    We present modeling on the evaluation of the modulation performance of semiconductor laser coupled with an ultra-short external cavity in terms of the intensity modulation (IM) response, relative intensity noise (RIN), carrier to noise ratio (CNR), and frequency chirp. The modulation is characterized along the period-doubling (PD) route to chaos induced by optical feedback (OFB). We focus on the possibility of increasing the modulation bandwidth by improving the carrier-photon resonance (CPR) frequency or inducing resonant modulation due to photon-photon resonance (PPR). We show that along the route to chaos, OFB could increase the CPR frequency and improve the 3 dB-modulation bandwidth from 19 GHz to 28 GHz. When strong OFB keeps the continuous wave (CW) operation or induces periodic oscillation (PO), PPR becomes significant and reveals resonance modulation over mm-frequency passband exceeding 50 GHz. Both CNR and frequency chirp are also enhanced around the CPR and PPR frequencies. The highest CNR peak is obtained when modulating the CW or PO laser, whereas the maximum peak of chirp corresponds to non-modulated chaotic laser.

  4. Characterization of a swept external cavity quantum cascade laser for rapid broadband spectroscopy and sensing

    DOE PAGES

    Brumfield, Brian E.; Taubman, Matthew S.; Suter, Jonathan D.; ...

    2015-09-21

    The performance of a rapidly swept external cavity quantum cascade laser (ECQCL) system combined with an open-path Herriott cell was evaluated for time-resolved measurements of chemical species with broad and narrow absorption spectra. A spectral window spanning 1278 – 1390 cm-1 was acquired at a 200 Hz acquisition rate, corresponding to a tuning rate of 2x104 cm-1/s, with a spectral resolution of 0.2 cm-1. The capability of the ECQCL to measure < 100 ppbv changes in N2O and F134A concentrations on millisecond timescales was demonstrated in simulated plume studies with releases near the open-path Herriott cell. Absorbance spectra measured usingmore » the ECQCL system exhibited noise-equivalent absorption coefficients of 5x10-9 cm-1Hz-1/2. For a spectrum acquisition time of 5 ms, noise-equivalent concentrations (NEC) for N2O and F134A were measured to be 70 and 16 ppbv respectively, which improved to sub-ppbv levels with averaging to 100 s. Noise equivalent column densities of 0.64 and 0.25 ppmv x m in 1 sec are estimated for N2O and F134A.« less

  5. Properties of leader-laggard chaos synchronization in mutually coupled external-cavity semiconductor lasers.

    PubMed

    Jiang, Ning; Pan, Wei; Luo, Bin; Yan, Lianshan; Xiang, Shuiying; Yang, Lei; Zheng, Di; Li, Nianqiang

    2010-06-01

    The properties of the leader-laggard chaos synchronization (LLCS) in two mutually coupled external-cavity semiconductor lasers are studied systematically. We theoretically analyze the general conditions for the LLCS based on the symmetric operation mechanism and numerically investigate the influences of operation parameters, the mismatch robustness, the chaos pass filtering effects, the communication performance, and the security of the system. It is demonstrated that stable LLCS, which allows simultaneous bidirectional message exchange in virtue of mutual chaos pass filtering effect, can be achieved in a wide operation region; moreover, high-quality LLCS and satisfactory communication performance can be maintained under a relatively large device parameter mismatch. Compared with the isochronal chaos synchronization in the same system, LLCS provides a wider operation region, a better mismatch robustness, and a stronger chaos pass filtering effect. In addition, the investigations on the security of private key message transmission under some potential attacks indicate that the security can be enhanced by increasing the bit rate moderately, exchanging messages with different bit rates, or monitoring the LLCS.

  6. Rate equations for vertical-cavity surface-emitting lasers

    SciTech Connect

    Sande, Guy van der; Danckaert, Jan; Veretennicoff, Irina; Erneux, Thomas

    2003-01-01

    By applying a multiple time scale perturbation method, we simplify the spin-flip model equations [San Miguel et al., Phys. Rev. A 52, 1728 (1995)] describing the polarization behavior of vertical-cavity surface-emitting lasers. The reduced problem consists of three rate equations for a two-mode semiconductor laser. The asymptotic theory is based on the natural values of the laser parameters and considers the case of large values of the spin-flip rate and birefringence with respect to the relaxation oscillation frequency. Our analysis corrects and complements previous derivations of rate equations from the spin-flip model equations. We find that the cross-gain saturation coefficients due to spin-flip processes are not symmetric and may become negative. As a result, a new physical interpretation of polarization switching from the high-frequency mode to the low-frequency mode and for high values of the birefringence is possible.

  7. Semiconductor surface emitting lasers for photon pairs generation

    NASA Astrophysics Data System (ADS)

    Vanbever, Luc R.; Karpov, Evgueni; Panajotov, Krassimir

    2017-10-01

    We study the feasibility of generating photon pairs in a resonant Vertical-Cavity Surface-Emitting Laser (VCSEL) as a result of a third-order non-linear, four wave mixing interaction. We focus on degenerate four wave mixing in the spontaneous regime where two pump photons are annihilated to create a pair of signal and idler photons. Using the methods of quantum optics, we calculate the two-photon production rate, the spectrum of the generated photons, and the signal-idler cross-correlations. We highlight how the dispersion of the medium in the VCSEL cavity (a regular GaAs configuration) significantly diminishes the two-photon production rate. Based on our results, we enumerate the characteristics of a VCSEL that would be suitable for photon pair generation.

  8. 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.

  9. Tunable continuous-wave dual-wavelength laser by external-cavity superluminescent diode with a volume Bragg grating and a diffraction grating

    NASA Astrophysics Data System (ADS)

    Zheng, Yujin; Kurita, Takashi; Sekine, Takashi; Kato, Yoshinori; Kawashima, Toshiyuki

    2016-10-01

    We demonstrate the tunable continuous-wave dual-wavelength laser based on a double external-cavity superluminescent diode (SLD). The double external cavity consisted of a volume Bragg grating (VBG) and a diffraction grating bracketing the SLD's two facets. The VBG was used as an output coupler to enable the external-cavity SLD to achieve a stable wavelength. A narrow bandwidth of 0.25 nm was achieved in single-wavelength operation. The diffraction grating served as an end mirror to create another tunable wavelength external cavity for the SLD. A wavelength tuning range of 23 nm was achieved. The laser output of the double external-cavity SLD had a tunable spectral separation with dual-wavelengths from +6.42 to -16.94 nm. An output power of up to 37.7 mW was achieved with a frequency difference of 7.1 THz.

  10. Demonstration of a rapidly-swept external cavity quantum cascade laser for atmospheric sensing applications

    SciTech Connect

    Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.; Suter, Jonathan D.

    2016-07-01

    The application of quantum cascade lasers (QCLs) in atmospheric science for trace detection of gases has been demonstrated using sensors in point or remote sensing configurations. Many of these systems utilize single narrowly-tunable (~10 cm-1) distributed feedback (DFB-) QCLs that limit simultaneous detection to a restricted number of small chemical species like H2O or N2O. The narrow wavelength range of DFB-QCLs precludes accurate quantification of large chemical species with broad rotationally-unresolved vibrational spectra, such as volatile organic compounds, that play an important role in the chemistry of the atmosphere. External-cavity (EC-) QCL systems are available that offer tuning ranges >100 cm-1, making them excellent IR sources for measuring multiple small and large chemical species in the atmosphere. While the broad wavelength coverage afforded by an EC system enables measurements of large chemical species, most commercial systems can only be swept over their entire wavelength range at less than 10 Hz. This prohibits broadband simultaneous measurements of multiple chemicals in plumes from natural or industrial sources where turbulence and/or chemical reactivity are resulting in rapid changes in chemical composition on sub-1s timescales. At Pacific Northwest National Laboratory we have developed rapidly-swept EC-QCL technology that acquires broadband absorption spectra (~100 cm-1) on ms timescales. The spectral resolution of this system has enabled simultaneous measurement of narrow rotationally-resolved atmospherically-broadened lines from small chemical species, while offering the broad tuning range needed to measure broadband spectral features from multiple large chemical species. In this talk the application of this technology for open-path atmospheric measurements will be discussed based on results from laboratory measurements with simulated plumes of chemicals. The performance offered by the system for simultaneous detection of multiple chemical

  11. Standoff hyperspectral imaging of explosives residues using broadly tunable external cavity quantum cascade laser illumination

    NASA Astrophysics Data System (ADS)

    Bernacki, Bruce E.; Phillips, Mark C.

    2010-04-01

    We describe experimental results on the detection of explosives residues with active hyperspectral imaging by illumination of the target surface using an external cavity quantum cascade laser (ECQCL) and imaging using an uncooled microbolometer camera. Explosives have rich absorption features in the molecular fingerprint region that spans 1500 to 500 wavenumbers and is easily probed by the wavelength range of quantum cascade lasers (QCL), which can be fabricated to emit from 3300 to 400 wavenumbers. Our laboratory-built ECQCL consists of a Fabry-Pérot laser with anti-reflection coated front facet that is arranged in a Littman-Metcalf configuration. The ECQCL was operated quasi-CW with a 100 kHz repetition rate, 50% duty cycle drive signal and tuning range from 1102.95 to 983.8 wavenumbers. The active hyperspectral imaging technique forms an image hypercube by recording one image for each tuning step of the ECQCL. For the experiments reported here, each wavelength band was 2 wavenumbers wide and 60 bands of image data were acquired in 2 seconds. The resulting hyperspectral image contains the full absorption spectrum produced by the illumination laser at each pixel in the image which can then be used to identify the explosive type and relative quantity using the rich library of spectral identification approaches developed initially in the remote sensing community. These techniques include spectral feature fitting, matched filtering, and mixture tuned matched filtering. Mixtures of materials can be evaluated using linear spectral unmixing approaches and matched filtering or mixture tuned matched filtering. We provide examples of these methods using ENVI, a commercial spectral image processing software package.

  12. Broadband spectroscopy with external cavity quantum cascade lasers beyond conventional absorption measurements.

    PubMed

    Lambrecht, Armin; Pfeifer, Marcel; Konz, Werner; Herbst, Johannes; Axtmann, Felix

    2014-05-07

    Laser spectroscopy is a powerful tool for analyzing small molecules, i.e. in the gas phase. In the mid-infrared spectral region quantum cascade lasers (QCLs) have been established as the most frequently used laser radiation source. Spectroscopy of larger molecules in the gas phase, of complex mixtures, and analysis in the liquid phase requires a broader tuning range and is thus still the domain of Fourier transform infrared (FTIR) spectroscopy. However, the development of tunable external cavity (EC) QCLs is starting to change this situation. The main advantage of QCLs is their high spectral emission power that is enhanced by a factor of 10(4) compared with thermal light sources. Obviously, transmission measurements with EC-QCLs in strongly absorbing samples are feasible, which can hardly be measured by FTIR due to detector noise limitations. We show that the high power of EC-QCLs facilitates spectroscopy beyond simple absorption measurements. Starting from QCL experiments with liquid samples, we show results of fiber evanescent field analysis (FEFA) to detect pesticides in drinking water. FEFA is a special case of attenuated total reflection spectroscopy. Furthermore, powerful CW EC-QCLs enable fast vibrational circular dichroism (VCD) spectroscopy of chiral molecules in the liquid phase - a technique which is very time consuming with standard FTIR equipment. We present results obtained for the chiral compound 1,1'-bi-2-naphthol (BINOL). Finally, powerful CW EC-QCLs enable the application of laser photothermal emission spectroscopy (LPTES). We demonstrate this for a narrowband and broadband absorber in the gas phase. All three techniques have great potential for MIR process analytical applications.

  13. Wavelength beam combining of a 980-nm tapered diode laser bar in an external cavity

    NASA Astrophysics Data System (ADS)

    Vijayakumar, Deepak; Jensen, Ole Bjarlin; Thestrup, Birgitte

    2010-04-01

    High power diode lasers are used in a large number of applications. A limiting factor for more widespread use of broad area lasers is the poor beam quality. Gain guided tapered diode lasers are ideal candidates for industrial applications that demands watt level output power with good beam quality. By adapting a bar geometry, the output power could be scaled even up to several tens of watts. Unfortunately, the high divergence which is a characteristic feature of the bar geometry could lead to a degradation of the overall beam quality of the laser bar. However, spectral beam combining is an effective solution for preserving the beam quality of the bar in the range of that of a single emitter and at the same time, enabling the power scaling. We report spectral beam combining applied to a 12 emitter tapered laser bar at 980 nm. The external cavity has been designed for a wavelength separation of 4.0 nm between the emitters. An output power of 9 W has been achieved at an operating current of 30 A. The combined beam had an M2 value (1/e2) of 5.3 along the slow axis which is comparable to that of a single tapered emitter on the laser bar. The overall beam combining efficiency was measured to be 63%. The output spectrum of the individual emitters was narrowed considerably. In the free running mode, the individual emitters displayed a broad spectrum of the order of 0.5-1.0 nm while the spectral width has been reduced to 30-100 pm in the spectral beam combining mode.

  14. Continuously current-tunable, narrow line-width miniaturized external cavity diode laser at 633 nm

    NASA Astrophysics Data System (ADS)

    Sumpf, B.; Bawamia, A.; Blume, G.; Eppich, B.; Ginolas, A.; Spießberger, S.; Thomas, M.; Erbert, G.

    2012-03-01

    Red emitting diode lasers with a narrow spectral line-width and continuous tuning are requested as light sources for interferometric measurements with nm-accuracy. Tuning ranges of about 25 GHz together with a spectral line-width smaller than 10 MHz are necessary. A current-tunable miniaturized 633 nm external cavity diode laser (ECDL) will be presented. The resonator is formed without moving parts between the front facet of a semiconductor gain medium and a reflection Bragg grating (RBG). The RBG has a high reflectivity larger than 95% in a small spectral bandwidth, which is approximately equal to the targeted tuning range. Within this bandwidth, the ECDL is tunable by changing the injection current of the gain medium. The length of the resonator is selected so short, that the distance between the laser modes is larger than the tuning range. Herewith, single mode operation should be guaranteed. The device is mounted on an aluminum nitride bench with a footprint of 5 mm x 10 mm. ECDLs using gain media with different front facet reflectivities of 30% and 70% will be compared. Moreover, results for a device encapsulated in a silicon based gel will be presented. For a device with 30% front facet reflectivity in air, a maximal output power of 10 mW was achieved. The tuning range without any mode-hops was 34 pm, i.e. 25 GHz. The line-width was smaller than 10 MHz. The emitted beam was approximately diffraction limited with a M2 ~ 1.1 in both directions.

  15. High-power quantum-dot tapered tunable external-cavity lasers based on chirped and unchirped structures.

    PubMed

    Haggett, Stephanie; Krakowski, Michel; Montrosset, Ivo; Cataluna, Maria Ana

    2014-09-22

    A high-power tunable external cavity laser configuration with a tapered quantum-dot semiconductor optical amplifier at its core is presented, enabling a record output power for a broadly tunable semiconductor laser source in the 1.2 - 1.3 µm spectral region. Two distinct optical amplifiers are investigated, using either chirped or unchirped quantum-dot structures, and their merits are compared, considering the combination of tunability and high output power generation. At 1230 nm, the chirped quantum-dot laser achieved a maximum power of 0.62 W and demonstrated nearly 100-nm tunability. The unchirped laser enabled a tunability range of 32 nm and at 1254 nm generated a maximum power of 0.97 W, representing a 22-fold increase in output power compared with similar narrow-ridge external-cavity lasers at the same current density.

  16. Design of a mode-hop-free tunable external cavity diode laser with a PLZT electro-optic ceramic deflector

    NASA Astrophysics Data System (ADS)

    Sun, Yan-guang; Wei, Fang; Chen, Di-jun; Xin, Guo-feng; Ye, Qing; Cai, Hai-wen; Qu, Rong-hui

    2011-06-01

    A stable tunable external cavity diode laser (ECDL) which uses an intracavity electro-optic deflector incorporated into a Littrow-type external cavity as a wavelength tunable element is proposed. The deflector comprises an antireflection-coated rectangle Lead Lanthanum Zirconate Titanate (PLZT) electro-optic ceramic with a pair of parallel trapezoidal electrodes on the up and down surfaces, which can simultaneously change the cavity length and the beam-grating angle to achieve mode-hop-free tuning. The theory for mode-hop-free tuning will be presented in this paper, and the model calculations predict that the laser can be tuned continuously by as much as 110GHz. This new approach is simple in structure with no mechanical moving parts and has potential configuration of compact grating-stabilized ECDL.

  17. Tunable single-mode Fabry-Perot laser diode using a built-in external cavity and its modulation characteristics.

    PubMed

    Jeong, Yong Deok; Won, Yong Hyub; Choi, Sang Ook; Yoon, Jong Hyun

    2006-09-01

    A tunable single-mode laser is obtained by using a weakly coupled cavity structure involved in a coaxially packaged Fabry-Perot laser diode. The cleaved end facet of the coupling fiber becomes an optical reflector and forms an external cavity with a laser facet. The single-mode oscillation condition is controlled and stabilized by tuning the operating temperature. The tuning range is about 10 nm with the side-mode suppression ratio of more than 27 dB when the temperature changes from 11.5 degrees C to 25 degrees C. Direct modulation characteristics were investigated, and our results show that a shorter external cavity can bear deeper modulation depth.

  18. Four-channel optically pumped atomic magnetometer for magnetoencephalography

    PubMed Central

    Colombo, Anthony P.; Carter, Tony R.; Borna, Amir; Jau, Yuan-Yu; Johnson, Cort N.; Dagel, Amber L.; Schwindt, Peter D. D.

    2016-01-01

    We have developed a four-channel optically pumped atomic magnetometer for magnetoencephalography (MEG) that incorporates a passive diffractive optical element (DOE). The DOE allows us to achieve a long, 18-mm gradiometer baseline in a compact footprint on the head. Using gradiometry, the sensitivities of the channels are < 5 fT/Hz1/2, and the 3-dB bandwidths are approximately 90 Hz, which are both sufficient to perform MEG. Additionally, the channels are highly uniform, which offers the possibility of employing standard MEG post-processing techniques. This module will serve as a building block of an array for magnetic source localization. PMID:27410816

  19. Four-channel optically pumped atomic magnetometer for magnetoencephalography.

    PubMed

    Colombo, Anthony P; Carter, Tony R; Borna, Amir; Jau, Yuan-Yu; Johnson, Cort N; Dagel, Amber L; Schwindt, Peter D D

    2016-07-11

    We have developed a four-channel optically pumped atomic magnetometer for magnetoencephalography (MEG) that incorporates a passive diffractive optical element (DOE). The DOE allows us to achieve a long, 18-mm gradiometer baseline in a compact footprint on the head. Using gradiometry, the sensitivities of the channels are < 5 fT/Hz1/2, and the 3-dB bandwidths are approximately 90 Hz, which are both sufficient to perform MEG. Additionally, the channels are highly uniform, which offers the possibility of employing standard MEG post-processing techniques. This module will serve as a building block of an array for magnetic source localization.

  20. Scaling of an Optically Pumped Mid-Infrared Rubidium Laser

    DTIC Science & Technology

    2015-03-26

    A maximum slope efficiency based on incident pump photons of 1.7 × 10-4 was observed. Evidence that only a small percentage (ɚ%) of the available...Optically pumped 62P3/2 - 6 2S1/2 and 6 2P1/2 - 6 2S1/2 Rb lasing has been demonstrated in the past on two occasions. Sharma demonstrated a continuous...concentration on laser output energy. Specifically, it was demonstrated that bleached limit, slope efficiency, and laser output energy scale

  1. Optically pumped subwavelength-scale metallodielectric nanopatch resonators

    PubMed Central

    Kwon, Kyungmok; You, Jong-bum; Shim, Jaeho; Jung, Youngho; Yu, Kyoungsik

    2016-01-01

    We discuss subwavelength-scale semiconductor metal-optic resonators placed on the metal substrate with various top metal plate sizes. Albeit with large optical losses, addition of metal layers converts a leaky semiconductor nano-block into a highly-confined optical cavity. Optically pumped lasing action is observed with the extended top metal layer that can significantly suppress the radiation losses. Careful investigation of self-heating effects during the optical carrier injection process shows the importance of temperature-dependent material properties in the laser rate equation model and the overall laser performances. PMID:27549640

  2. Optically pumped subwavelength-scale metallodielectric nanopatch resonators

    NASA Astrophysics Data System (ADS)

    Kwon, Kyungmok; You, Jong-Bum; Shim, Jaeho; Jung, Youngho; Yu, Kyoungsik

    2016-08-01

    We discuss subwavelength-scale semiconductor metal-optic resonators placed on the metal substrate with various top metal plate sizes. Albeit with large optical losses, addition of metal layers converts a leaky semiconductor nano-block into a highly-confined optical cavity. Optically pumped lasing action is observed with the extended top metal layer that can significantly suppress the radiation losses. Careful investigation of self-heating effects during the optical carrier injection process shows the importance of temperature-dependent material properties in the laser rate equation model and the overall laser performances.

  3. Optically pumped subwavelength-scale metallodielectric nanopatch resonators.

    PubMed

    Kwon, Kyungmok; You, Jong-Bum; Shim, Jaeho; Jung, Youngho; Yu, Kyoungsik

    2016-08-23

    We discuss subwavelength-scale semiconductor metal-optic resonators placed on the metal substrate with various top metal plate sizes. Albeit with large optical losses, addition of metal layers converts a leaky semiconductor nano-block into a highly-confined optical cavity. Optically pumped lasing action is observed with the extended top metal layer that can significantly suppress the radiation losses. Careful investigation of self-heating effects during the optical carrier injection process shows the importance of temperature-dependent material properties in the laser rate equation model and the overall laser performances.

  4. Note: Spin-exchange optical pumping in a van

    NASA Astrophysics Data System (ADS)

    Chauvin, C.; Liagre, L.; Boutin, C.; Mari, E.; Léonce, E.; Carret, G.; Coltrinari, B.; Berthault, P.

    2016-01-01

    The advent of spin-hyperpolarization techniques designed to overcome the sensitivity issue of nuclear magnetic resonance owing to polarization transfer from more ordered systems has recently raised great enthusiasm. However, the out-of-equilibrium character of the polarization requires a close proximity between the area of production and the site of use. We present here a mobile spin-exchange optical pumping setup that enables production of laser-polarized noble gases in a standalone mode, in close proximity to hospitals or research laboratories. Only compressed air and mains power need to be supplied by the host laboratory.

  5. DBR-free optically pumped semiconductor disk lasers

    NASA Astrophysics Data System (ADS)

    Yang, Zhou; Albrecht, Alexander R.; Cederberg, Jeffrey G.; Sheik-Bahae, Mansoor

    2015-03-01

    Optically pumped semiconductor disk lasers (SDLs) provide high beam quality with high average-power power at designer wavelengths. However, material choices are limited by the need for a distributed Bragg reflector (DBR), usually monolithically integrated with the active region. We demonstrate DBR-free SDL active regions, which have been lifted off and bonded to various transparent substrates. For an InGaAs multi-quantum well sample bonded to a diamond window heat spreader, we achieved CW lasing with an output power of 2 W at 1150 nm with good beam quality.

  6. Steady-state heating of active fibres under optical pumping

    SciTech Connect

    Gainov, V V; Shaidullin, R I; Ryabushkin, Oleg A

    2011-07-31

    We have measured the temperature in the core of rare-earth-doped optical fibres under lasing conditions at high optical pump powers using a fibre Mach - Zehnder interferometer and probe light of wavelength far away from the absorption bands of the active ions. From the observed heating kinetics of the active medium, the heat transfer coefficient on the polymer cladding - air interface has been estimated. The temperature of the active medium is shown to depend on the thermal and optical properties of the polymer cladding. (fiber and integrated optics)

  7. Note: Spin-exchange optical pumping in a van

    SciTech Connect

    Chauvin, C.; Liagre, L.; Boutin, C.; Mari, E.; Léonce, E.; Carret, G.; Coltrinari, B.; Berthault, P.

    2016-01-15

    The advent of spin-hyperpolarization techniques designed to overcome the sensitivity issue of nuclear magnetic resonance owing to polarization transfer from more ordered systems has recently raised great enthusiasm. However, the out-of-equilibrium character of the polarization requires a close proximity between the area of production and the site of use. We present here a mobile spin-exchange optical pumping setup that enables production of laser-polarized noble gases in a standalone mode, in close proximity to hospitals or research laboratories. Only compressed air and mains power need to be supplied by the host laboratory.

  8. Simplified approach for quantitative calculations of optical pumping

    NASA Astrophysics Data System (ADS)

    Atoneche, Fred; Kastberg, Anders

    2017-07-01

    We present a simple and pedagogical method for quickly calculating optical pumping processes based on linearised population rate equations. The method can easily be implemented on mathematical software run on modest personal computers, and can be generalised to any number of concrete situations. We also show that the method is still simple with realistic experimental complications taken into account, such as high level degeneracy, impure light polarisation, and an added external magnetic field. The method and the associated mathematical toolbox should be of value in advanced physics teaching, and can also facilitate the preparation of research tasks.

  9. Stark effect in optically pumped molecular submillimeter lasers

    NASA Astrophysics Data System (ADS)

    Rak, V. G.; Dyubko, S. F.

    1980-06-01

    A theoretical analysis is made of the effects which take place in optically pumped lasers whose active medium is subjected to a dc electric Geld. The possibilities are discussed of tuning the frequency and modulating the intensity of the radiation emitted by a laser. The gain characteristics of an active medium in an electric field are calculated for a CH3F laser operating on a wavelength of 496 μ. It is shown that the frequency tuning limits of the output radiation of such a laser can reach 3 GHz, if the active medium allows electric fields of up to 30 kV/cm to be applied.

  10. Four-channel optically pumped atomic magnetometer for magnetoencephalography

    DOE PAGES

    Colombo, Anthony P.; Carter, Tony R.; Borna, Amir; ...

    2016-06-29

    We have developed a four-channel optically pumped atomic magnetometer for magnetoencephalography (MEG) that incorporates a passive diffractive optical element (DOE). The DOE allows us to achieve a long, 18-mm gradiometer baseline in a compact footprint on the head. Using gradiometry, the sensitivities of the channels are < 5 fT/Hz1/2, and the 3-dB bandwidths are approximately 90 Hz, which are both sufficient to perform MEG. Additionally, the channels are highly uniform, which offers the possibility of employing standard MEG post-processing techniques. As a result, this module will serve as a building block of an array for magnetic source localization.

  11. Four-channel optically pumped atomic magnetometer for magnetoencephalography

    DOE PAGES

    Colombo, Anthony P.; Carter, Tony R.; Borna, Amir; ...

    2016-06-29

    We have developed a four-channel optically pumped atomic magnetometer for magnetoencephalography (MEG) that incorporates a passive diffractive optical element (DOE). The DOE allows us to achieve a long, 18-mm gradiometer baseline in a compact footprint on the head. Using gradiometry, the sensitivities of the channels are < 5 fT/Hz1/2, and the 3-dB bandwidths are approximately 90 Hz, which are both sufficient to perform MEG. Additionally, the channels are highly uniform, which offers the possibility of employing standard MEG post-processing techniques. As a result, this module will serve as a building block of an array for magnetic source localization.

  12. Optically pumped semiconductor lasers for atomic and molecular physics

    NASA Astrophysics Data System (ADS)

    Burd, S.; Leibfried, D.; Wilson, A. C.; Wineland, D. J.

    2015-03-01

    Experiments in atomic, molecular and optical (AMO) physics rely on lasers at many different wavelengths and with varying requirements on spectral linewidth, power and intensity stability. Optically pumped semiconductor lasers (OPSLs), when combined with nonlinear frequency conversion, can potentially replace many of the laser systems currently in use. We are developing a source for laser cooling and spectroscopy of Mg+ ions at 280 nm, based on a frequency quadrupled OPSL with the gain chip fabricated at the ORC at Tampere Univ. of Technology, Finland. This OPSL system could serve as a prototype for many other sources used in atomic and molecular physics.

  13. Four-channel optically pumped atomic magnetometer for magnetoencephalography

    SciTech Connect

    Colombo, Anthony P.; Carter, Tony R.; Borna, Amir; Jau, Yuan -Yu; Johnson, Cort N.; Dagel, Amber L.; Schwindt, Peter D. D.

    2016-06-29

    We have developed a four-channel optically pumped atomic magnetometer for magnetoencephalography (MEG) that incorporates a passive diffractive optical element (DOE). The DOE allows us to achieve a long, 18-mm gradiometer baseline in a compact footprint on the head. Using gradiometry, the sensitivities of the channels are < 5 fT/Hz1/2, and the 3-dB bandwidths are approximately 90 Hz, which are both sufficient to perform MEG. Additionally, the channels are highly uniform, which offers the possibility of employing standard MEG post-processing techniques. As a result, this module will serve as a building block of an array for magnetic source localization.

  14. Development of an optically pumped polarized deuterium target

    SciTech Connect

    Young, L.; Holt, R.J.; Green, M.C.; Kowalczyk, R.

    1987-01-01

    The development of a polarized deuterium target for internal use at an electron storage ring is of great interest for fundamental studies in nuclear physics. In order to achieve the maximum allowable target thickness, 10/sup 14/ nuclei/cm/sup 2/, consistent with various constraints imposed by the storage ring environment, a flux of 4 x 10/sup 17/ polarized atom/s must be provided. This flux exceeds the capability of conventional atomic beam sources by an order of magnitude. We have been developing an alternative source based upon the spin-exchange optical pumping method in which the flux is limited only by laser power. 7 refs., 1 fig.

  15. High sensitivity detection of NO2 employing cavity ringdown spectroscopy and an external cavity continuously tunable quantum cascade laser.

    PubMed

    Rao, Gottipaty N; Karpf, Andreas

    2010-09-10

    A trace gas sensor for the detection of nitrogen dioxide based on cavity ringdown spectroscopy (CRDS) and a continuous wave external cavity tunable quantum cascade laser operating at room temperature has been designed, and its features and performance characteristics are reported. By measuring the ringdown times of the cavity at different concentrations of NO(2), we report a sensitivity of 1.2 ppb for the detection of NO(2) in Zero Air.

  16. Uncertainty evaluation and electronic improvements of a wavemeter to measure the wavelength of an external cavity diode laser

    NASA Astrophysics Data System (ADS)

    Outumuro, I.; Valencia, J. L.; Diz-Bugarin, J.; Blanco, J.; Dorrío, B. V.

    2015-04-01

    A Michelson wavemeter was developed to test the accuracy and give traceability to the wavelength of external cavity diode lasers. These lasers were stabilized using a Littrow configuration and an iodine gas cell as frequency reference, and they were used as light sources in the assembly of a new interferometric system for the gauge block calibration. Previously, a microcontroller counting device with a Vernier logic and the uncertainty evaluation of the Michelson wavemeter had to be made.

  17. Characterization of a Low-phase-noise, High-power (370 mW), External-Cavity Semiconductor Laser

    DTIC Science & Technology

    2010-07-21

    Naval Research Laboratory Washington, DC 20375-5320 NRL/MR/5670--10-9272 Characterization of a Low- phase -noise, High-power (370 mW), External...NUMBER OF PAGES 17. LIMITATION OF ABSTRACT Characterization of a Low- phase -noise, High-power (370 mW), External-cavity Semiconductor Laser R.E...404-2077 Past research efforts have attempted to demonstrate semiconductor lasers with reduced levels of phase noise, approaching noise levels

  18. Continuous-wave wavelength conversion for high-power applications using an external cavity diamond Raman laser.

    PubMed

    Kitzler, Ondrej; McKay, Aaron; Mildren, Richard P

    2012-07-15

    We demonstrate continuous-wave (cw) operation of a diamond Raman laser at 1240 nm in an external cavity configuration. The output power increased linearly with pump power with a 49.7% slope efficiency and reached 10.1 W at the maximum available pump power of 31 W. The combination of resonator design with diamond provides a novel approach to power-scalable cw wavelength and beam conversion.

  19. Efficient phase noise suppression of an external-cavity diode-laser by optical filtering and resonant optical feedback

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; Miyakawa, S.; Kasai, K.; Okada-Shudo, Y.; Watanabe, M.

    2012-07-01

    We experimentally demonstrated that the excess phase noise of an external cavity diode laser (ECDL) can be efficiently suppressed by optical filtering and resonant optical feedback techniques. A suppression of more than 40 dB phase noise was obtained for the first time using these methods. It made that the phase noise of the ECDL reached shot noise level from 15 MHz. This opens a new way to reduce the phase noise of diode lasers.

  20. Binary arithmetic using optical symbolic substitution and integrated phototransistor surface-emitting laser logic.

    PubMed

    Cheng, J; Olbright, G R; Bryan, R P

    1991-10-20

    We outline an architecture for performing binary addition by using optical symbolic substitution and optical logic gates based on heterojunctionphototransistors and verticalcavity surface-emitting lasers.

  1. Tunable high-power narrow-linewidth semiconductor laser based on an external-cavity tapered amplifier.

    PubMed

    Chi, Mingjun; Jensen, Ole Bjarlin; Holm, Jesper; Pedersen, Christian; Andersen, Peter Eskil; Erbert, Götz; Sumpf, Bernd; Petersen, Paul Michael

    2005-12-26

    A high-power narrow-linewidth laser system based on a tapered semiconductor optical amplifier in external cavity is demonstrated. The external cavity laser system uses a new tapered amplifier with a super-large optical-cavity (SLOC) design that leads to improved performance of the external cavity diode lasers. The laser system is tunable over a 29 nm range centered at 802 nm. As high as 1.95 W output power is obtained at 803.84 nm, and an output power above 1.5 W is achieved from 793 to 812 nm at operating current of 3.0 A. The emission linewidth is below 0.004 nm and the beam quality factor M2 is below 1.3 over the 29 nm tunable range. As an example of application, the laser system is used as a pump source for the generation of 405 nm blue light by single-pass frequency doubling in a periodically poled KTiOPO4. An output power of 24 mW at 405 nm, corresponding to a conversion efficiency of 0.83%/W is attained.

  2. The analysis and system design for MCG measurement based on optically pumped cesium magnetometer

    NASA Astrophysics Data System (ADS)

    Yang, Zhang; Chong, Kang; Wang, Qingtao; Lei, Cheng; Zheng, Caiping

    2010-11-01

    At present, laser optical pumping magnetometer of sensitivity is continuous improved and can measure the range from Earth magnetic field to the bio-magnetic field. In the bio-magnetic field, magnetocardiography (MCG) is paid also more and more attention. In this paper, we will discuss cesium optically pumped magnetometer theoretical analysis, system design, the magnetic field gradient measuring principle. On this basis, we build optically pumped magnetometer in a gradient structure for the cardiac magnetic measurements and filter through the wavelet transform. Based on optical pumping magnetometer measuring MCG will be applied in life science, clinical medicine and other fields.

  3. Visible light emitting vertical cavity surface emitting lasers

    DOEpatents

    Bryan, R.P.; Olbright, G.R.; Lott, J.A.; Schneider, R.P. Jr.

    1995-06-27

    A vertical cavity surface emitting laser that emits visible radiation is built upon a substrate, then having mirrors, the first mirror on top of the substrate; both sets of mirrors being a distributed Bragg reflector of either dielectrics or other materials which affect the resistivity or of semiconductors, such that the structure within the mirror comprises a plurality of sets, each having a thickness of {lambda}/2n where n is the index of refraction of each of the sets; each of the mirrors adjacent to spacers which are on either side of an optically active bulk or quantum well layer; and the spacers and the optically active layer are from one of the following material systems: In{sub z}(Al{sub y}Ga{sub 1{minus}y}){sub 1{minus}z}P, InAlGaAs, AlGaAs, InGaAs, or AlGaP/GaP, wherein the optically active region having a length equal to m {lambda}/2n{sub eff} where m is an integer and n{sub eff} is the effective index of refraction of the laser cavity, and the spacer layer and one of the mirrors being transmissive to radiation having a wavelength of {lambda}/n, typically within the green to red portion of the visible spectrum. 10 figs.

  4. Visible light emitting vertical cavity surface emitting lasers

    DOEpatents

    Bryan, Robert P.; Olbright, Gregory R.; Lott, James A.; Schneider, Jr., Richard P.

    1995-01-01

    A vertical cavity surface emitting laser that emits visible radiation is built upon a substrate, then having mirrors, the first mirror on top of the substrate; both sets of mirrors being a distributed Bragg reflector of either dielectrics or other materials which affect the resistivity or of semiconductors, such that the structure within the mirror comprises a plurality of sets, each having a thickness of .lambda./2n where n is the index of refraction of each of the sets; each of the mirrors adjacent to spacers which are on either side of an optically active bulk or quantum well layer; and the spacers and the optically active layer are from one of the following material systems: In.sub.z (Al.sub.y Ga.sub.1-y).sub.1-z P, InAlGaAs, AlGaAs, InGaAs, or AlGaP/GaP, wherein the optically active region having a length equal to m .lambda./2n.sub.eff where m is an integer and n.sub.eff is the effective index of refraction of the laser cavity, and the spacer layer and one of the mirrors being transmissive to radiation having a wavelength of .lambda./n, typically within the green to red portion of the visible spectrum.

  5. Affect of an electrostatic wave on optical pumping

    NASA Astrophysics Data System (ADS)

    Skiff, Frederick; Chu, Feng

    2016-09-01

    Extensive information can be obtained on wave-particle interactions and wave fields by direct measurement of perturbed ion distribution functions using laser-induced fluorescence (LIF). For practical purposes, LIF is normally performed on metastable states - here we consider singly ionized Argon in an inductively coupled plasma. Wave detection is best performed using phase-coherent detection, but power spectra can be obtained through correlation functions. If laser intensity is increased to obtain a better LIF signal, then the effects of optical pumping will produce systematic effects depending on the collision rates which control metastable population and lifetime. We simulate the wave-detection process using a Lagrangian model for the LIF signal. This approach separates the classical dynamics of the ion orbits from the quantum-state transitions produced by optical pumping. The two dynamics nevertheless become coupled in the presence of an electrostatic wave. The numerical simulation is compared with experimental data from a CW magnetized plasma discharge with externally launched ion acoustic waves. Work supported by US DOE DE-FG02ER54543.

  6. Spontaneous emission effects in optically pumped x-ray FEL

    SciTech Connect

    Smetanin, I.V.; Grigor`ev, S.V.

    1995-12-31

    An effect of spontaneous emission in both quantum and classical regimes of the optically pumped X-ray free electron laser (FEL) in investigated. The quantum properties of an FEL are determined by the ratio of the separation {h_bar} between the absorption and emission lines (i.e. the quanta emitted) and their effective width {Delta}{epsilon} {eta}={h_bar}/{Delta}{epsilon}. In the conventional classical regime {eta} {much_lt} 1 an electron emits and absorbes a great number of shortwavelength photons over the interaction region, the gain in FEL being the result of these competitive processes. In the quantum limit {eta} {much_gt} 1 the emission and absorption lines are completely separated and thus the FEL becomes a two-level quantum oscillator with a completely inverted active medium. Spontaneous emission causes the electron to leave the range of energies where resonant interaction with the laser field occurs, thus effectively reducing the number of particles that take part in generating the induced X-ray signal. This effect is found to be crucial for lasing in optically pumped X-ray FEL. The characteristic relaxation times are calculated for both classical and quantum FEL regimes. It is shown that spontaneous emission results in FEL electron beam threshold current, which is of rather high value. An optimal range of pumping laser intensities is determined.

  7. Spin-Exchange Optical Pumping of Solid Alkali Compounds

    NASA Astrophysics Data System (ADS)

    Patton, Brian; Ishikawa, Kiyoshi; Jau, Yuan-Yu; Happer, William

    2007-03-01

    Spin-exchange optical pumping of noble gases has been used for many years to create highly non-equilibrium spin populations, with applications ranging from fundamental physics[1] to medical imaging[2]. In this procedure, angular momentum is transferred from circularly-polarized laser light to the electron spins of an alkali vapor and ultimately to the nuclei of a gas such as ^3He or ^129Xe. Here we show experimentally that a similar process can be used to polarize the nuclei of a solid film of cesium hydride which coats the walls of an optical pumping cell. We present nuclear magnetic resonance (NMR) data which demonstrate that the nuclear polarization of ^133Cs in CsH can be enhanced above the Boltzmann limit in a 9.4-Tesla magnetic field. Possible spin-exchange mechanisms will be discussed, as well as the extension of this technique to other compounds. [1] T. W. Kornack, R. K. Ghosh, and M. V. Romalis, Phys. Rev. Lett. 95, 23080 (2005). [2] M. S. Conradi, D. A. Yablonskiy, et al., Acad. Radiol. 12, 1406 (2005).

  8. Optical Pumping / Spin Exchange ^3He Neutron Spin Filter Development

    NASA Astrophysics Data System (ADS)

    Hwang, Shenq-Rong; Coulter, Kevin P.; Chupp, Timothy E.; Welsh, Robert C.

    1998-04-01

    We have instrumented a thermal neutron beam line at the 2MW Ford reactor at the University of Michigan to develop a ^3He neutron spin filter test stand. Due to a large, spin depedent neutron cross section at low energies, polarized ^3He can be used as a neutron spin filter. Our ^3He spin filter is a 10 amagat-cm ^3He cell polarized via optical pumping/spin exchange with Rb. The filter is made of Corning 7056 glass filled with Rb , several atmosphere of ^3He and a few hundred torr nitrogen as buffer gas. We apply two 15W diode array lasers to optically pump Rb. In this presentation we will discuss some progress of this development, including a rotating oven design and a stepping motor driven neutron chopper. Preliminary results of the 10 amagat-cm filter will be presented and compared with theoretical calculations. A study of systematic errors from the data acquisition system and the neutron chopper will also be discussed.

  9. Measuring gas temperature during spin-exchange optical pumping process

    NASA Astrophysics Data System (ADS)

    Normand, E.; Jiang, C. Y.; Brown, D. R.; Robertson, L.; Crow, L.; Tong, X.

    2016-04-01

    The gas temperature inside a Spin-Exchange Optical Pumping (SEOP) laser-pumping polarized 3He cell has long been a mystery. Different experimental methods were employed to measure this temperature but all were based on either modelling or indirect measurement. To date there has not been any direct experimental measurement of this quantity. Here we present the first direct measurement using neutron transmission to accurately determine the number density of 3He, the temperature is obtained using the ideal gas law. Our result showed a surprisingly high gas temperature of 380°C, compared to the 245°C of the 3He cell wall temperature and 178°C of the optical pumping oven temperature. This experiment result may be used to further investigate the unsolved puzzle of the "X-factor" in the SEOP process which places an upper bound to the 3He polarization that can be achieved. Additional spin relaxation mechanisms might exist due to the high gas temperature, which could explain the origin of the X-factor.

  10. Demonstration of a Rapidly-Swept External Cavity Quantum Cascade Laser for Atmospheric Sensing Applications

    NASA Astrophysics Data System (ADS)

    Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.; Suter, Jonathan D.

    2016-06-01

    The application of quantum cascade lasers (QCLs) in atmospheric science for trace detection of gases has been demonstrated using sensors in point or remote sensing configurations. Many of these systems utilize single narrowly-tunable (˜10 wn) distributed feedback (DFB-) QCLs that limit simultaneous detection to a restricted number of small chemical species like H2O or N2O. The narrow wavelength range of DFB-QCLs precludes accurate quantification of large chemical species with broad rotationally-unresolved vibrational spectra, such as volatile organic compounds, that play an important role in the chemistry of the atmosphere. External-cavity (EC-) QCL systems are available that offer tuning ranges greater than 100 wn, making them excellent IR sources for measuring multiple small and large chemical species in the atmosphere. While the broad wavelength coverage afforded by an EC system enables measurements of large chemical species, most commercial systems can only be swept over their entire wavelength range at less than 10 Hz. This prohibits broadband simultaneous measurements of multiple chemicals in plumes from natural or industrial sources where turbulence and/or chemical reactivity are resulting in rapid changes in chemical composition on sub-1s timescales. At Pacific Northwest National Laboratory we have developed rapidly-swept EC-QCL technology that acquires broadband absorption spectra (˜100 wn) on ms timescales. The spectral resolution of this system has enabled simultaneous measurement of narrow rotationally-resolved atmospherically-broadened lines from small chemical species, while offering the broad tuning range needed to measure broadband spectral features from multiple large chemical species. In this talk the application of this technology for open-path atmospheric measurements will be discussed based on results from laboratory measurements with simulated plumes of chemicals. The performance offered by the system for simultaneous detection of multiple

  11. A theoretical performance study of an external cavity fiber Fabry-Perot interferometer for displacement measurement

    NASA Astrophysics Data System (ADS)

    Arumugam, Kumar

    The objective of this research is to explore a mathematical model developed by Wilkinson and Pratt for the external cavity fiber-based Fabry-Perot interferometer (EFPI) and to create a Michelson interferometer setup to validate a frequency modulation component of this model. A laser diode with nominal wavelength 635 nm is modulated by oscillating the diode current of maximum amplitude 22.62 mA to create correspondingly varying wavelength. Experiments are included to evaluate a rotating vector representation of the modulation harmonics in the signal received at the photodetector as of a cube corner translated by a piezo-electric actuator is displaced. Wavelength modulation as a function of diode current, the coherence length of the laser, and characteristics of the modulation harmonics are evaluated. A real time DAQ system and two lock-in amplifiers are utilized for detecting three side-band harmonics of the signal. For short range displacements this interferometer setup is monitored using a capacitance displacement sensor. The capacitance displacement measurement differed from the Michelson interferometer by 160 nm. The piezoelectric stage actuated with a 15 V Ramp signal produced 2.54 mum displacement of the cube corner. The setup is tested with Ramp signals of 75 V to 1.5 V and with the Ramp periods of 1 to 20 seconds to find the resolution of the interferometer, modulation of the wavelength sensitivity and the coherence length of the laser as 10.53 nm, 1.786 nm·A-1 and >1 m respectively. The best quadrature signal achieved corresponded to modulating the laser at amplitude of 18.86 mA at 1 kHz frequency with a path length difference of 6.35 mm. The amplitude comparison of side-band harmonics with Bessel function curves is consistent with a modulation amplitude of 1.28 rad corresponding to amplitude ratios of 0.5 (second and first) , 0.15 (third and second) and 0.06 (third and first) in the first through third Bessel function values.

  12. Heterogeneously bonded vertical cavity surface emitting lasers and thermal modeling

    NASA Astrophysics Data System (ADS)

    Jeong, Hyejin

    Typically semiconductor materials used for photonic devices have been limited to those exhibiting a direct bandgap. In order to incorporate indirect bandgap and non-semiconducting materials, extensive research efforts have been put into developing hybrid photonic devices, which consist of different materials for the light emitting region and the substrate. In this dissertation, a post-fabrication bonding technique for integrating semiconductor vertical cavity surface emitting lasers (VCSELs) onto hybrid substrates is demonstrated. This approach provides flexibility regarding the choice of device fabrication and hybrid substrate materials. Light output versus injected current and applied voltage characteristics of lasers are measured before and after the transfer process. VCSEL arrays transferred onto Si substrate show that the transfer technique does not degrade the laser performance. VCSEL transfer onto a polyethylene terephthalate (PET) substrate allows for flexible arrays, but with degraded performance due to excessive thermal dissipation. A VCSEL array with an area of 1.0 x 1.2 mm2 is transferred onto a Cu substrate which has a higher thermal conductivity compared to both GaAs and PET. For the transfer bonding process, the final device yield is enhanced by including an etch stop layer in the epitaxial wafer. In order to study the effect of the thermal conductivity of the substrate on the dissipation of heat from the VCSELs, we present a simple VCSEL electro-thermal model, in which an agreement is obtained between simulation and experiment for lasing wavelength with varying laser diameter. Using this model, the thermal limitations of the VCSEL output on different substrates is discussed.

  13. Red vertical cavity surface emitting lasers (VCSELs) for consumer applications

    NASA Astrophysics Data System (ADS)

    Duggan, Geoffrey; Barrow, David A.; Calvert, Tim; Maute, Markus; Hung, Vincent; McGarvey, Brian; Lambkin, John D.; Wipiejewski, Torsten

    2008-02-01

    There are many potential applications of visible, red (650nm - 690nm) vertical cavity surface emitting lasers (VCSELs) including high speed (Gb) communications using plastic optical fiber (POF), laser mouse sensors, metrology, position sensing. Uncertainty regarding the reliability of red VCSELs has long been perceived as the most significant roadblock to their commercialization. In this paper we will present data on red VCSELs optimized for performance and reliability that will allow exploitation of this class of VCSEL in a wide range of high volume consumer, communication and medical applications. VCSELs operating at ~665nm have been fabricated on 4" GaAs substrates using MOCVD as the growth process and using standard VCSEL processing technology. The active region is AlGaInP-based and the DBR mirrors are made from AlGaAs. Threshold currents are typically less than 2mA, the devices operate up to >60C and the light output is polarized in a stable, linear characteristic over all normal operating conditions. The 3dB modulation bandwidth of the devices is in excess of 3GHz and we have demonstrated the operation of a transceiver module operating at 1.25Gb/s over both SI-POF and GI-POF. Ageing experiments carried out using a matrix of current and temperature stress conditions allows us to estimate that the time to failure of 1% of devices (TT1%F) is over 200,000h for reasonable use conditions - making these red VCSELs ready for commercial exploitation in a variety of consumer-type applications. Experiments using appropriate pulsed driving conditions have resulted in operation of 665nm VCSELs at a temperature of 85°C whilst still offering powers useable for eye-safe free space and POF communications.

  14. Widely Tunable Mode-Hop-Free External-Cavity Quantum Cascade Laser

    NASA Technical Reports Server (NTRS)

    Wysocki, Gerard; Curl, Robert F.; Tittel, Frank K.

    2010-01-01

    The external-cavity quantum cascade laser (EC-QCL) system is based on an optical configuration of the Littrow type. It is a room-temperature, continuous wave, widely tunable, mode-hop-free, mid-infrared, EC-QCL spectroscopic source. It has a single-mode tuning range of 155 cm(exp -1) (approximately equal to 8% of the center wavelength) with a maximum power of 11.1 mW and 182 cm(exp -1) (approximately equal to 15% of the center wavelength), and a maximum power of 50 mW as demonstrated for 5.3 micron and 8.4 micron EC-QCLs, respectively. This technology is particularly suitable for high-resolution spectroscopic applications, multi-species tracegas detection, and spectroscopic measurements of broadband absorbers. Wavelength tuning of EC-QCL spectroscopic source can be implemented by varying three independent parameters of the laser: (1) the optical length of the gain medium (which, in this case, is equivalent to QCL injection current modulation), (2) the length of the EC (which can be independently varied in the Rice EC-QCL setup), and (3) the angle of beam incidence at the diffraction grating (frequency tuning related directly to angular dispersion of the grating). All three mechanisms of frequency tuning have been demonstrated and are required to obtain a true mode-hop-free laser frequency tuning. The precise frequency tuning characteristics of the EC-QCL output have been characterized using a variety of diagnostic tools available at Rice University (e.g., a monochromator, FTIR spectrometer, and a Fabry-Perot spectrometer). Spectroscopic results were compared with available databases (such as HITRAN, PNNL, EPA, and NIST). These enable precision verification of complete spectral parameters of the EC-QCL, such as wavelength, tuning range, tuning characteristics, and line width. The output power of the EC-QCL is determined by the performance of the QC laser chip, its operating conditions, and parameters of the QC laser cavity such as mirror reflectivity or intracavity

  15. TOPICAL REVIEW: Optically pumped nanowire lasers: invited review

    NASA Astrophysics Data System (ADS)

    Zimmler, Mariano A.; Capasso, Federico; Müller, Sven; Ronning, Carsten

    2010-02-01

    This paper reviews several topics related to optically pumped ZnO nanowire lasers. A systematic study of the various properties of a device as it evolves from the regime of amplified spontaneous emission to laser oscillation above threshold is presented. The key dependence of the laser threshold on nanowire diameter is demonstrated and explained by means of a thorough study of guided modes in semiconducting nanowires for a nanowire-on-substrate geometry. A 'head on' detection geometry is used to measure the far-field profile of a nanowire laser and thus identify the modes responsible for lasing. Finally, the temperature behavior of a nanowire laser is reported, and possible mechanisms that may be responsible for gain are suggested.

  16. Optically Pumped NMR in the Fractional Quantum Hall Regime

    NASA Astrophysics Data System (ADS)

    Barrett, S. E.; Kuzma, N. N.; Khandelwal, P.; Pfeiffer, L. N.; West, K. W.

    1998-03-01

    Optically Pumped Nuclear Magnetic Resonance measurements are a local probe of the electron spin degree of freedom in n-type GaAs quantum wells.(S.E.Barrett et al.,Phys.Rev.Lett.72),1368(1994).^, footnote S. E. Barrett et al., Phys. Rev. Lett. 74, 5112 (1995)^, footnote R. Tycko et al., Science 268, 1460 (1995). We have recently shown that this OPNMR technique can be carried out in fields up to B=12 Tesla and temperatures down to T=0.3 K, making this technique a viable new probe of the Fractional Quantum Hall regime. We will discuss our latest measurements in these conditions, and compare our new results with previous measurements and the existing theoretical models for this regime.

  17. Optical pumping system design for large production of hyperpolarized.

    PubMed

    Ruset, I C; Ketel, S; Hersman, F W

    2006-02-10

    We present a design for a spin-exchange optical pumping system to produce large quantities of highly polarized 129Xe. Low xenon concentrations in the flowing gas mixture allow the laser to maintain high Rb polarization. The large spin-exchange rate between Rb and 129Xe through the long-lived van der Waals molecules at low pressure, combined with a high flow rate, results in large production rates of hyperpolarized xenon. We report a maximum polarization of 64% achieved for a 0.3 l/h Xe flow rate, and maximum magnetization output of 6 l/h at 22% polarization. Our findings regarding the polarization dependence on temperature, nitrogen partial pressure, and gas mixture flow velocity are also reported.

  18. Optical pumping of rubidium atoms in a parahydrogen matrix

    NASA Astrophysics Data System (ADS)

    Weinstein, Jonathan; Arnott, W. Patrick; Christy, Tim; Hartzell, Chase; Kanagin, Andrew; Momose, Takamasa; Patterson, David; Upadhyay, Sunil

    2016-05-01

    Building on prior work with rubidium atoms in a cryogenic argon matrix, we have grown solid parahydrogen crystals doped with rubidium atoms. Typical rubidium densities are on the order of 1017 cm-3. We have demonstrated optical pumping of the atomic spin of the implanted rubidium atoms; the measured spin polarization signals are roughly one order of magnitude larger than what was achieved in argon matrices. The combination of high atomic densities and optical addressability make this a promising experimental platform for applications such as magnetometry and fundamental physics measurements. Spin lifetimes (T1) on the order of 1 second have been observed. Progress towards measuring coherence times (T2) will be discussed. This material is based on work supported by the National Science Foundation under Grant No. PHY 1265905.

  19. Optical Pumping of Rubidium Spin in a Solid Argon Matrix

    NASA Astrophysics Data System (ADS)

    Regmi, Sameer K.

    Using the matrix isolation technique we have trapped rubidium atoms inside a cryogenic solid argon crystal of thickness 200 mum. This weakly-interacting solid offers the experimental simplicity and high densities of solid-state systems, while allowing the implanted atoms to retain many of the properties of their gas-phase counterparts. As such, they are a promising environment for quantum information experiments, as well as sensors such as magnetometers. We spectroscopically observed narrow lines at 799 nm, 785 nm, and 747 nm, and investigated optical pumping of the implanted rubidium atoms. We observed that the absorption spectrum of the rubidium could be modified by incident laser light. This modification could be reversed by applying an additional light source. In addition, we were able to create spin polarization and measure a longitudinal spin relaxation time T1 of about 0.1 s.

  20. Spin-Exchange Optical Pumping of He-3

    NASA Astrophysics Data System (ADS)

    Walker, Thad

    2015-04-01

    Spin-exchange optical pumping, in which angular momentum is transferred from light to alkali atoms to He-3, is a powerful method for producing large quantities of highly polarized nuclei for electron scattering experiments and neutron spin filters/analyzers. Technical innovations (exquisite aluminosilicate glass cells with T1 >> 100 hours, > 100 Watt frequency-narrowed diode lasers) and improved understanding of the atomic physics processes involved (precision polarimetry, hybrid spin-exchange, circular dichroism), have resulted in orders of magnitude scale-up from the nascent experiments in the late 1980s. Improved understanding of effects such as the X-factor and particulate formation are needed to further advance the conversion of spin-polarized light into seminal physics results.

  1. Spin-Exchange Optical Pumping of Solid Alkali Compounds

    NASA Astrophysics Data System (ADS)

    Patton, Brian; Ishikawa, Kiyoshi; Jau, Yuan-Yu; Happer, William

    2007-06-01

    We demonstrate enhancement of the ^133Cs nuclear polarization in a film of cesium hydride which has been placed in contact with an optically pumped cesium vapor. The maximum observed polarization at 9.4 T and 137 ^oC is roughly 4 times the equilibrium polarization, but higher magnetizations are possible at lower magnetic fields. In an attempt to determine the mechanism of spin transfer from the alkali vapor to the solid, we have performed this experiment at intermediate magnetic fields (1-2 tesla) while pumping different optical transitions in the vapor. We will discuss the predicted spin current to the CsH layer in this regime of partial hyperfine decoupling and propose new methods for generating even higher polarizations in the solid. Potential applications of this technique will be mentioned as well as its extension to other compounds.

  2. Recycle Rate in a Pulsed, Optically Pumped Rubidium Laser

    SciTech Connect

    Miller, Wooddy S.; Sulham, Clifford V.; Holtgrave, Jeremy C.; Perram, Glen P.

    2010-10-08

    A pulsed, optically pumped rubidium laser operating in analogy to the diode pumped alkali laser (DPAL) system at pump intensities as high as 750 kW/cm{sup 2} has been demonstrated with output energies of up to 13 {mu}J/pulse. Output energy is dramatically limited by spin-orbit relaxation rates under these high intensity pump conditions. More than 250 photons are available for every rubidium atom in the pumped volume, requiring a high number of cycles per atom during the 2-8 ns duration of the pump pulse. At 550 Torr of ethane, the spin-orbit relaxation rate is too slow to effectively utilize all the incident pump photons. Indeed, a linear dependence of output energy on pump pulse duration for fixed pump energy is demonstrated.

  3. Submillimeter D2O-18 molecular laser with optical pumping

    NASA Astrophysics Data System (ADS)

    Svich, V. A.; Pokormiakho, N. G.; Topkov, A. N.

    1980-11-01

    In the considered investigation, nine new emission lines of the D2O-18 molecule were observed over the wavelength range from 96 to 140 micrometers. In the experiments, a CO2 TEA laser was used for optical pumping. The TEA laser was operated at atmospheric pressure with an output energy up to 2 J and a pulse length of 100 ns. A gaseous mixture with a composition of CO2:N2:He = 1:1:4 was excited by means of a pulsed transverse discharge. A resonator with a length of 1 m was formed by a spherical mirror with a radius of curvature of 10 m, and a gold-plated echelette grating with 100 lines/mm. The submillimeter cell consisted of a glass tube with an inside diameter of 80 mm and a length of 1270 mm, and the spherical mirrors of the submillimeter resonator.

  4. Ultrashort pulse generation from vertical cavity surface emitting semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Jasim, Khalil E.

    This work presents the first demonstration of a passively modelocked extended vertical cavity surface emitting laser (VECSEL) diode. Three cavity configurations were used to sustain stable passive modelocking operation: the Z-shaped, V-shaped and linear cavities. A semiconductor saturable absorber mirror (SESAM) used to triggered passive modelocking of the VECSEL diode. The SESAM device was used as a nonlinear high reflector in the Z-shaped and V-shaped cavity configurations, while it served as an output coupler (SESAMOC) in the linear cavity after the substrate was being angle polished and antireflection coated to eliminate any etalon effects. Many examples of VECSEL diode passive modelocking results will be presented. The standard non-collinear second-harmonic autocorrelation technique has been used to measure the generated pulse width, which was as small as 23 psec. The VECSEL-SESAM configuration has generated stable pulse trains at repetition rates ranging from 1 GHz to approximately 6 GHz, depending on the resonator configuration. Modelocking operation was stable and robust as amplitude noise measurements revealed a noise level ˜0.8%. Moreover, harmonic passive modelocking operation has been observed for the first time during the investigation of modelocking dynamics and stability in the regime of strong self-feedback coupling >10%. A reverse biased p-i-n QW device has enabled the generation of a stable pulse train at 15 GHz with pulse duration close to 15 psec and amplitude noise level ˜0.3%. However, due to design limitations of both the active and passive VECSELs, driving the system to produce repetition rates close to 20 GHz resulted in pulse amplitude variation and an unavoidable DC background. These initial results suggest the possibility of design and fabrication of an integrated or monolithic structure, which may lead to operation of the device at repetition rates beyond 50 GHz with sub-ps pulse durations. Although our VECSEL diode emits 980 nm

  5. III-Nitride Vertical-Cavity Surface-Emitting Lasers

    NASA Astrophysics Data System (ADS)

    Leonard, John T.

    Vertical-cavity surface-emitting lasers (VCSELs) have a long history of development in GaAs-based and InP-based systems, however III-nitride VCSELs research is still in its infancy. Yet, over the past several years we have made dramatic improvements in the lasing characteristics of these highly complex devices. Specifically, we have reduced the threshold current density from ˜100 kA/cm2 to ˜3 kA/cm2, while simultaneously increasing the output power from ˜10 muW to ˜550 muW. These developments have primarily come about by focusing on the aperture design and intracavity contact design for flip-chip dual dielectric DBR III-nitride VCSELs. We have carried out a number of studies developing an Al ion implanted aperture (IIA) and photoelectrochemically etched aperture (PECA), while simultaneously improving the quality of tin-doped indium oxide (ITO) intracavity contacts, and demonstrating the first III-nitride VCSEL with an n-GaN tunnel junction intracavity contact. Beyond these most notable research fronts, we have analyzed numerous other parameters, including epitaxial growth, flip-chip bonding, substrate removal, and more, bringing further improvement to III-nitride VCSEL performance and yield. This thesis aims to give a comprehensive discussion of the relevant underlying concepts for nonpolar VCSELs, while detailing our specific experimental advances. In Section 1, we give an overview of the applications of VCSELs generally, before describing some of the potential applications for III-nitride VCSELs. This is followed by a summary of the different material systems used to fabricate VCSELs, before going into detail on the basic design principles for developing III-nitride VCSELs. In Section 2, we outline the basic process and geometry for fabricating flip-chip nonpolar VCSELs with different aperture and intracavity contact designs. Finally, in Section 3 and 4, we delve into the experimental results achieved in the last several years, beginning with a discussion on

  6. Characteristics of the single-longitudinal-mode planar-waveguide external cavity diode laser at 1064 nm.

    PubMed

    Numata, Kenji; Alalusi, Mazin; Stolpner, Lew; Margaritis, Georgios; Camp, Jordan; Krainak, Michael

    2014-04-01

    We describe the characteristics of the planar-waveguide external cavity diode laser (PW-ECL). To the best of our knowledge, it is the first butterfly-packaged 1064 nm semiconductor laser that is stable enough to be locked to an external frequency reference. We evaluated its performance from the viewpoint of precision experiments. Using a hyperfine absorption line of iodine, we suppressed its frequency noise by a factor of up to 10(4) at 10 mHz. The PW-ECL's compactness and low cost make it a candidate to replace traditional Nd:YAG nonplanar ring oscillators and fiber lasers in applications that require a single longitudinal mode.

  7. Characteristics of the Single-Longitudinal-Mode Planar-Waveguide External Cavity Diode Laser at 1064 nm

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Alalusi, Mazin; Stolpner, Lew; Margaritis, Georgios; Camp, Jordan; Krainak, Michael

    2014-01-01

    We describe the characteristics of the planar-waveguide external cavity diode laser (PW-ECL). To the best of our knowledge, it is the first butterfly-packaged 1064 nm semiconductor laser that is stable enough to be locked to an external frequency reference. We evaluated its performance from the viewpoint of precision experiments. Using a hyperfine absorption line of iodine, we suppressed its frequency noise by a factor of up to 104 at 10 mHz. The PWECL's compactness and low cost make it a candidate to replace traditional Nd:YAG nonplanar ring oscillators and fiber lasers in applications that require a single longitudinal mode.

  8. Characteristics of the Single-Longitudinal-Mode Planar-Waveguide External Cavity Diode Laser at 1064 nm

    NASA Technical Reports Server (NTRS)

    Numata, Kenji; Alalusi, Mazin; Stolpner, Lew; Margaritis, Georgios; Camp, Jordan B.; Krainak, Michael A.

    2014-01-01

    We describe the characteristics of the planar-waveguide external cavity diode laser (PW-ECL). To the best of our knowledge, it is the first butterfly-packaged 1064-nm semiconductor laser that is stable enough to be locked to an external frequency reference. We evaluated its performance from the viewpoint of precision experiments. Especially, using a hyperfine absorption line of iodine, we suppressed its frequency noise by a factor of up to104 at 10 mHz. The PW-ECLs compactness and low cost make it a candidate to replace traditional Nd:YAGnon-planar ring oscillators and fiber lasers in applications which require a single longitudinal-mode.

  9. LASERS: Low-frequency power and pointing noises of a spectrally-selective external-cavity diode laser

    NASA Astrophysics Data System (ADS)

    Bruevich, V. V.; Elizarov, S. G.; Parashchuk, D. Yu

    2006-05-01

    The spectral density of low-frequency power noise and pointing noises of an external cavity AlGaAs/GaAs laser in Littman—Metcalf configuration is studied in the frequency region up to 1 kHz. The relative level of the power and pointing noises in the laser operating on a single longitudinal mode of the external resonator was ~10-6 Hz-1/2 and did not change substantially when the feedback was switched off. Long-term intensity fluctuations caused by intermode switchings did not exceed 2%.

  10. Tunable External Cavity Quantum Cascade Lasers (EC-QCL): an application field for MOEMS based scanning gratings

    NASA Astrophysics Data System (ADS)

    Grahmann, Jan; Merten, André; Ostendorf, Ralf; Fontenot, Michael; Bleh, Daniela; Schenk, Harald; Wagner, Hans-Joachim

    2014-03-01

    In situ process information in the chemical, pharmaceutical or food industry as well as emission monitoring, sensitive trace detection and biological sensing applications would increasingly rely on MIR-spectroscopic anal­ysis in the 3 μm - 12 μm wavelength range. However, cost effective, portable, low power consuming and fast spectrometers with a wide tuning range are not available so far. To provide these MIR-spectrometer properties, the combination of quantum cascade lasers with a MOEMS scanning grating as wavelength selective element in the external cavity is addressed to provide a very compact and fast tunable laser source for spectroscopic analysis.

  11. Real-Time Trace Gas Sensing of Fluorocarbons using a Swept-wavelength External Cavity Quantum Cascade Laser

    SciTech Connect

    Phillips, Mark C.; Taubman, Matthew S.; Bernacki, Bruce E.; Cannon, Bret D.; Stahl, Robert D.; Schiffern, John T.; Myers, Tanya L.

    2014-05-04

    We present results demonstrating real-time sensing of four different fluorocarbons at low-ppb concentrations using an external cavity quantum cascade laser (ECQCL) operating in a swept-wavelength configuration. The ECQCL was repeatedly swept over its full tuning range at a 20 Hz rate with a scan rate of 3535 cm-1/s, and a detailed characterization of the ECQCL scan stability and repeatability is presented. The sensor was deployed on a mobile automotive platform to provide spatially resolved detection of fluorocarbons in outdoor experiments. Noise-equivalent detection limits of 800-1000 parts-per-trillion (ppt) are demonstrated for 1 s integration times.

  12. Lithographic wavelength control of an external cavity laser with a silicon photonic crystal cavity-based resonant reflector.

    PubMed

    Liles, Alexandros A; Debnath, Kapil; O'Faolain, Liam

    2016-03-01

    We report the experimental demonstration of a new design for external cavity hybrid lasers consisting of a III-V semiconductor optical amplifier (SOA) with fiber reflector and a photonic crystal (PhC)-based resonant reflector on SOI. The silicon reflector is composed of an SU8 polymer bus waveguide vertically coupled to a PhC cavity and provides a wavelength-selective optical feedback to the laser cavity. This device exhibits milliwatt-level output power and side-mode suppression ratios of more than 25 dB.

  13. Infrared hyperspectral imaging using a broadly tunable external cavity quantum cascade laser and microbolometer focal plane array

    SciTech Connect

    Phillips, Mark C.; Ho, Nicolas

    2008-02-04

    A versatile mid-infrared hyperspectral imaging system is demonstrated by combining a broadly tunable external cavity quantum cascade laser and a microbolometer focal plane array. The tunable mid-infrared laser provided high brightness illumination over a tuning range from 985 cm-1 to 1075 cm-1 (9.30-10.15 μm). Hypercubes containing images at 300 wavelengths separated by 0.3 cm 1 were obtained in 12 s. High spectral resolution chemical imaging of methanol vapor was demonstrated for both static and dynamic systems. The system was also used to image and characterize multiple component liquid and solid samples.

  14. Mode-locked operation of Cr⁴⁺:YAG single-crystal fiber laser with external cavity.

    PubMed

    Ishibashi, Shigeo; Naganuma, Kazunori

    2014-03-24

    We report what is to our knowledge the first mode-locked Cr⁴⁺:YAG single-crystal fiber laser, which generates pulses of 120-fs duration with an output power of 23 mW at a center wavelength of 1520 nm for a single pulse in a cavity-round-trip. The laser contains a single-crystal fiber multi-mode waveguide about 120 μm in diameter and 40-mm long. The fundamental transverse mode is selected with an external cavity. This design strategy turned out to be well suited for direct high-power-laser-diode pumping.

  15. External cavity diode laser-based detection of trace gases with NICE-OHMS using current modulation.

    PubMed

    Centeno, R; Mandon, J; Cristescu, S M; Axner, O; Harren, F J M

    2015-03-09

    We combine an external cavity diode laser with noise-immune cavity-enhanced optical heterodyne molecular spectroscopy (NICE-OHMS) using current modulation. With a finesse of 1600, we demonstrate noise equivalent absorption sensitivities of 4.1 x 10(-10) cm(-1) Hz(-1/2), resulting in sub-ppbv detection limits for Doppler-broadened transitions of CH(4) at 6132.3 cm(-1), C(2)H(2) at 6578.5 cm(-1) and HCN at 6541.7 cm(-1). The system is used for hydrogen cyanide detection from sweet almonds.

  16. Tunable high-power narrow-spectrum external-cavity diode laser based on tapered amplifier at 668 nm.

    PubMed

    Chi, Mingjun; Erbert, G; Sumpf, B; Petersen, Paul Michael

    2010-05-15

    A 668 nm tunable high-power narrow-spectrum diode laser system based on a tapered semiconductor optical amplifier in external cavity is demonstrated. The laser system is tunable from 659to675 nm. As high as 1.38 W output power is obtained at 668.35 nm. The emission spectral bandwidth is less than 0.07 nm throughout the tuning range, and the beam quality factor M(2) is 2.0 with the output power of 1.27 W.

  17. Low-frequency power and pointing noises of a spectrally-selective external-cavity diode laser

    SciTech Connect

    Bruevich, V V; Elizarov, S G; Parashchuk, D Yu

    2006-05-31

    The spectral density of low-frequency power noise and pointing noises of an external cavity AlGaAs/GaAs laser in Littman-Metcalf configuration is studied in the frequency region up to 1 kHz. The relative level of the power and pointing noises in the laser operating on a single longitudinal mode of the external resonator was {approx}10{sup -6} Hz{sup -1/2} and did not change substantially when the feedback was switched off. Long-term intensity fluctuations caused by intermode switchings did not exceed 2%. (lasers)

  18. Planar-waveguide external cavity laser stabilization for an optical link with 10(-19) frequency stability.

    PubMed

    Clivati, Cecilia; Mura, Alberto; Calonico, Davide; Levi, Filippo; Costanzo, Giovanni A; Calosso, Claudio E; Godone, Aldo

    2011-12-01

    We stabilized the frequency of a compact planar-waveguide external cavity laser (ECL) on a Fabry-Perot cavity (FPC) through a Pound-Drever-Hall scheme. The residual frequency stability of the ECL is 10(-14), comparable to the stability achievable with a fiber laser (FL) locked to an FPC through the same scheme. We set up an optical link of 100 km, based on fiber spools, that reaches 10(-19) relative stability, and we show that its performances using the ECL or FL are comparable. Thus ECLs could serve as an excellent replacement for FLs in optical links where cost-effectiveness and robustness are important considerations.

  19. Monolithic arrays of grating-surface-emitting diode lasers and quantum well modulators for optical communications

    NASA Technical Reports Server (NTRS)

    Carlson, N. W.; Evans, G. A.; Liew, S. K.; Kaiser, C. J.

    1990-01-01

    The electro-optic switching properties of injection-coupled coherent 2-D grating-surface-emitting laser arrays with multiple gain sections and quantum well active layers are discussed and demonstrated. Within such an array of injection-coupled grating-surface-emitting lasers, a single gain section can be operated as intra-cavity saturable loss element that can modulate the output of the entire array. Experimental results demonstrate efficient sub-nanosecond switching of high power grading-surface-emitting laser arrays by using only one gain section as an intra-cavity loss modulator.

  20. Wavelength diversity in optically pumped alkali vapor lasers

    NASA Astrophysics Data System (ADS)

    Perram, Glen P.

    2017-01-01

    Alternative wavelengths for optically pumped alkali vapor lasers have been developed using single photon excitation of higher lying P-states, stimulated Raman processes, two-photon excitation of S and D states, and electric quadruple excitation on S-D transitions. Two photon excitation of Cs 72D leads to competing and cascade lasing producing red and infrared lasers operating on the D-P transitions, followed by ultraviolet, blue, the standard near infrared DPAL transitions operating on P-S transitions. The S-D pump transitions are fully bleached at pump intensities exceeding 1 MW/cm2, allowing for lasing transitions that terminate on the ground state. The kinetics of these systems are complex due to competition for population inversion among the many optical transitions. An optically pumped mid-infrared rubidium pulsed, mirrorless laser has also been demonstrated in a heat pipe along both the 62P3/2 - 62S1/2 transition at 2.73 μm and the 62P1/2 - 62S1/2 transition at 2.79 μm with a maximum energy of 100 nJ. Performance improves dramatically as the rubidium vapor density is increased, in direct contradiction with the prior work. No scaling limitations associated with energy pooling or ionization kinetics have been observed. Practical application for infrared counter measures depends on the further development of blue diode pump sources. Finally, stimulated electronic Raman scattering and hyper-Raman processes in potassium vapor near the D1 and D2 lines have been observed using a stable resonator and pulsed laser excitation. First and second order Stokes and anti-Stokes lines were observed simultaneously and independently for a pump laser tuning range exceeding 70 cm-1. When the pump is tuned between the K D1 and D2 lines, an efficient hyper-Raman process dominates with a slope efficiency that exceeds 10%. Raman shifted laser may be useful as a target illuminator or atmospheric compensation beacon for a high power diode pumped alkali laser.

  1. Lateral cavity photonic crystal surface emitting lasers with ultralow threshold and large power

    NASA Astrophysics Data System (ADS)

    Wang, Yufei; Qu, Hongwei; Zhou, Wenjun; Jiang, Bin; Zhang, Jianxin; Qi, Aiyi; Liu, Lei; Fu, Feiya; Zheng, Wanhua

    2012-03-01

    The Bragg diffraction condition of surface-emitting lasing action is analyzed and Γ2-1 mode is chosen for lasing. Two types of lateral cavity photonic crystal surface emitting lasers (LC-PCSELs) based on the PhC band edge mode lateral resonance and vertical emission to achieve electrically driven surface emitting laser without distributed Bragg reflectors in the long wavelength optical communication band are designed and fabricated. Deep etching techniques, which rely on the active layer being or not etched through, are adopted to realize the LC-PCSELs on the commercial AlGaInAs/InP multi-quantum-well (MQW) epitaxial wafer. 1553.8 nm with ultralow threshold of 667 A/cm2 and 1575 nm with large power of 1.8 mW surface emitting lasing actions are observed at room temperature, providing potential values for mass production with low cost of electrically driven PCSELs.

  2. Integration of photoactive and electroactive components with vertical cavity surface emitting lasers

    DOEpatents

    Bryan, R.P.; Esherick, P.; Jewell, J.L.; Lear, K.L.; Olbright, G.R.

    1997-04-29

    A monolithically integrated optoelectronic device is provided which integrates a vertical cavity surface emitting laser and either a photosensitive or an electrosensitive device either as input or output to the vertical cavity surface emitting laser either in parallel or series connection. Both vertical and side-by-side arrangements are disclosed, and optical and electronic feedback means are provided. Arrays of these devices can be configured to enable optical computing and neural network applications. 9 figs.

  3. Integration of photoactive and electroactive components with vertical cavity surface emitting lasers

    DOEpatents

    Bryan, Robert P.; Esherick, Peter; Jewell, Jack L.; Lear, Kevin L.; Olbright, Gregory R.

    1997-01-01

    A monolithically integrated optoelectronic device is provided which integrates a vertical cavity surface emitting laser and either a photosensitive or an electrosensitive device either as input or output to the vertical cavity surface emitting laser either in parallel or series connection. Both vertical and side-by-side arrangements are disclosed, and optical and electronic feedback means are provided. Arrays of these devices can be configured to enable optical computing and neural network applications.

  4. Tuning range and output power optimization of an external-cavity GaN diode laser at 455  nm.

    PubMed

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2016-03-20

    In this paper we discuss how different feedback gratings affect the tuning range and the output power of external feedback diode laser systems. A tunable high-power narrow-spectrum external-cavity diode laser system around 455 nm is investigated. The laser system is based on a high-power GaN diode laser in a Littrow external-cavity. Both a holographic diffraction grating and a ruled diffraction grating are used as feedback elements in the external cavity. The output power, spectral bandwidth, and tunable range of the external cavity diode laser system are measured and compared with the two gratings at different injected currents. When the holographic grating is used, the laser system can be tuned over a range of 1.4 nm with an output power around 530 mW. When the ruled grating is used, the laser system can be tuned over a range of 6.0 nm with an output power around 80 mW. The results can be used as a guide for selecting gratings for external-cavity diode lasers for different requirements.

  5. Ultra-sensitive Magnetic Microscopy with an Optically Pumped Magnetometer

    NASA Astrophysics Data System (ADS)

    Kim, Young Jin; Savukov, Igor

    2016-04-01

    Optically pumped magnetometers (OPMs) based on lasers and alkali-metal vapor cells are currently the most sensitive non-cryogenic magnetic field sensors. Many applications in neuroscience and other fields require high-resolution, high-sensitivity magnetic microscopic measurements. In order to meet this demand we combined a cm-size spin-exchange relaxation-free (SERF) OPM and flux guides (FGs) to realize an ultra-sensitive FG-OPM magnetic microscope. The FGs serve to transmit the target magnetic flux to the OPM thus improving both the resolution and sensitivity to small magnetic objects. We investigated the performance of the FG-OPM device using experimental and numerical methods, and demonstrated that an optimized device can achieve a unique combination of high resolution (80 μm) and high sensitivity (8.1 pT/). In addition, we also performed numerical calculations of the magnetic field distribution in the FGs to estimate the magnetic noise originating from the domain fluctuations in the material of the FGs. We anticipate many applications of the FG-OPM device such as the detection of micro-biological magnetic fields; the detection of magnetic nano-particles; and non-destructive testing. From our theoretical estimate, an FG-OPM could detect the magnetic field of a single neuron, which would be an important milestone in neuroscience.

  6. Ultra-sensitive magnetic microscopy with an optically pumped magnetometer

    DOE PAGES

    Kim, Young Jin; Savukov, Igor Mykhaylovich

    2016-04-22

    Optically pumped magnetometers (OPMs) based on lasers and alkali-metal vapor cells are currently the most sensitive non-cryogenic magnetic field sensors. Many applications in neuroscience and other fields require high-resolution, high-sensitivity magnetic microscopic measurements. In order to meet this demand we combined a cm-size spin-exchange relaxation-free (SERF) OPM and flux guides (FGs) to realize an ultra-sensitive FG-OPM magnetic microscope. The FGs serve to transmit the target magnetic flux to the OPM thus improving both the resolution and sensitivity to small magnetic objects. We investigated the performance of the FG-OPM device using experimental and numerical methods, and demonstrated that an optimized devicemore » can achieve a unique combination of high resolution (80 μm) and high sensitivity (8.1 pT/). Additionally, we also performed numerical calculations of the magnetic field distribution in the FGs to estimate the magnetic noise originating from the domain fluctuations in the material of the FGs. We anticipate many applications of the FG-OPM device such as the detection of micro-biological magnetic fields; the detection of magnetic nano-particles; and non-destructive testing. From our theoretical estimate, an FG-OPM could detect the magnetic field of a single neuron, which would be an important milestone in neuroscience.« less

  7. Optically Pumped Nuclear Magnetic Resonance in the Quantum Hall Regimes

    NASA Astrophysics Data System (ADS)

    Barrett, S. E.; Khandelwal, P.; Kuzma, N. N.; Pfeiffer, L. N.; West, K. W.

    1997-03-01

    Optical pumping enables the direct detection of the nuclear magnetic resonance signal of ^71Ga nuclei located in an electron doped GaAs quantum well.footnote S. E. Barrett et al., Phys. Rev. Lett. 72, 1368 (1994) Using this technique, measurements of the Knight shift (K_S)footnote S. E. Barrett et al., Phys. Rev. Lett. 74, 5112 (1995) and spin-lattice relaxation time (T_1)footnote R. Tycko et al., Science 268, 1460 (1995) have been carried out in the Quantum Hall regimes. This talk will focus on our latest measurements of KS and T1 near Landau level filling ν=1, which extend our earlier results to higher magnetic fields (B=12 Tesla) and lower temperatures (T < 1 Kelvin). We will compare these results to the theoretical predictionsfootnote S. L. Sondhi et al., Phys. Rev. B 47, 16419 (1993); H. A. Fertig et al., Phys. Rev. B 50, 11018 (1994) that the charged excitations of the ν = 1 ground state are novel spin textures called skyrmions. The current status of this picture will be discussed.

  8. Ultra-sensitive magnetic microscopy with an optically pumped magnetometer

    SciTech Connect

    Kim, Young Jin; Savukov, Igor Mykhaylovich

    2016-04-22

    Optically pumped magnetometers (OPMs) based on lasers and alkali-metal vapor cells are currently the most sensitive non-cryogenic magnetic field sensors. Many applications in neuroscience and other fields require high-resolution, high-sensitivity magnetic microscopic measurements. In order to meet this demand we combined a cm-size spin-exchange relaxation-free (SERF) OPM and flux guides (FGs) to realize an ultra-sensitive FG-OPM magnetic microscope. The FGs serve to transmit the target magnetic flux to the OPM thus improving both the resolution and sensitivity to small magnetic objects. We investigated the performance of the FG-OPM device using experimental and numerical methods, and demonstrated that an optimized device can achieve a unique combination of high resolution (80 μm) and high sensitivity (8.1 pT/). Additionally, we also performed numerical calculations of the magnetic field distribution in the FGs to estimate the magnetic noise originating from the domain fluctuations in the material of the FGs. We anticipate many applications of the FG-OPM device such as the detection of micro-biological magnetic fields; the detection of magnetic nano-particles; and non-destructive testing. From our theoretical estimate, an FG-OPM could detect the magnetic field of a single neuron, which would be an important milestone in neuroscience.

  9. Ultra-sensitive Magnetic Microscopy with an Optically Pumped Magnetometer.

    PubMed

    Kim, Young Jin; Savukov, Igor

    2016-04-22

    Optically pumped magnetometers (OPMs) based on lasers and alkali-metal vapor cells are currently the most sensitive non-cryogenic magnetic field sensors. Many applications in neuroscience and other fields require high-resolution, high-sensitivity magnetic microscopic measurements. In order to meet this demand we combined a cm-size spin-exchange relaxation-free (SERF) OPM and flux guides (FGs) to realize an ultra-sensitive FG-OPM magnetic microscope. The FGs serve to transmit the target magnetic flux to the OPM thus improving both the resolution and sensitivity to small magnetic objects. We investigated the performance of the FG-OPM device using experimental and numerical methods, and demonstrated that an optimized device can achieve a unique combination of high resolution (80 μm) and high sensitivity (8.1 pT/). In addition, we also performed numerical calculations of the magnetic field distribution in the FGs to estimate the magnetic noise originating from the domain fluctuations in the material of the FGs. We anticipate many applications of the FG-OPM device such as the detection of micro-biological magnetic fields; the detection of magnetic nano-particles; and non-destructive testing. From our theoretical estimate, an FG-OPM could detect the magnetic field of a single neuron, which would be an important milestone in neuroscience.

  10. Optically-pumped spin-exchange polarized electron source

    NASA Astrophysics Data System (ADS)

    Pirbhai, Munir Hussein

    Polarized electron beams are an indispensable probe of spin-dependent phenomena in fields of atomic and molecular physics, magnetism and biophysics. While their uses have become widespread, the standard source based on negative electron affinity gallium arsenide (GaAs) remains technically complicated. This has hindered progress on many experiments involving spin-polarized electrons, especially those using target gas loads, which tend to adversely affect the performance of GaAs sources. A robust system based on an alternative way to make polarized electron beams has been devised in this study, which builds on previous work done in our lab. It involves spin-exchange collisions between free, unpolarized electrons and oriented rubidium atoms in the presence of a quenching gas. This system has less stringent vacuum requirements than those of GaAs sources, and is capable of operating in background pressures of ~1mTorr. Beams with ~24% polarization and 4μA of current have been recorded, which is comparable to the performance obtained with the earlier version built in our lab. The present system is however not as unstable as in the previous work, and has the potential to be developed into a "turn-key" source of polarized electron beams. It has also allowed us to undertake a study to find factors which affect the beam polarization in this scheme of producing polarized electrons. Such knowledge will help us to design better optically-pumped spin-exchange polarized electron sources.

  11. Magnetic field imaging with microfabricated optically-pumped magnetometers.

    PubMed

    Alem, Orang; Mhaskar, Rahul; Jiménez-Martínez, Ricardo; Sheng, Dong; LeBlanc, John; Trahms, Lutz; Sander, Tilmann; Kitching, John; Knappe, Svenja

    2017-04-03

    A multichannel imaging system is presented, consisting of 25 microfabricated optically-pumped magnetometers. The sensor probes have a footprint of less than 1 cm2 and a sensitive volume of 1.5 mm × 1.5 mm × 1.5 mm and connect to a control unit through optical fibers of length 5 m. Operating at very low ambient magnetic fields, the sensor array has an average magnetic sensitivity of 24 fT/Hz1/2, with a standard deviation of 5 fT/Hz1/2 when the noise of each sensor is averaged between 10 and 50 Hz. Operating in Earth's magnetic field, the magnetometers have a field sensitivity around 5 pT/Hz1/2. The vacuum-packaged sensor heads are optically heated and consume on average 76 ± 7 mW of power each. The heating power is provided by an array of eight diode lasers. Magnetic field imaging of small probe coils was obtained with the sensor array and fits to the expected field pattern agree well with the measured data.

  12. Electron-spin-reversal phenomenon in optically pumped rubidium

    SciTech Connect

    Norrgard, E. B.; Dreiling, J. M.; Gay, T. J.; Tupa, D.

    2010-09-15

    We have studied the optical pumping of mixtures of Rb vapor and N{sub 2} buffer gas by laser light tuned to the D{sub 1} transition having a spectral width of {approx}500 MHz. The Rb densities are of the order of 10{sup 13} cm{sup -3}, while the buffer-gas pressures range from 0.1 to 10 torr. As the frequency of the right-hand circularly polarized laser is varied across the D{sub 1} absorption profile, the electron spin polarization of the Rb is found to take on negative values for small negative values of pump detuning from the absorption profile center. This occurs for N{sub 2} pressures below {approx}1 torr; at 10 torr the electron spins consistently point in the same direction as the angular momentum of the pump light. The spin-reversal effect can be understood in terms of populations of the F=2 ({sup 85}Rb) and F=1 ({sup 87}Rb) states caused by small unpolarized fractions in the pump beam and its elimination in terms of pressure broadening caused by the N{sub 2} buffer gas. We speculate that this effect could be used for fast Rb spin modulation.

  13. Ultra-sensitive Magnetic Microscopy with an Optically Pumped Magnetometer

    PubMed Central

    Kim, Young Jin; Savukov, Igor

    2016-01-01

    Optically pumped magnetometers (OPMs) based on lasers and alkali-metal vapor cells are currently the most sensitive non-cryogenic magnetic field sensors. Many applications in neuroscience and other fields require high-resolution, high-sensitivity magnetic microscopic measurements. In order to meet this demand we combined a cm-size spin-exchange relaxation-free (SERF) OPM and flux guides (FGs) to realize an ultra-sensitive FG-OPM magnetic microscope. The FGs serve to transmit the target magnetic flux to the OPM thus improving both the resolution and sensitivity to small magnetic objects. We investigated the performance of the FG-OPM device using experimental and numerical methods, and demonstrated that an optimized device can achieve a unique combination of high resolution (80 μm) and high sensitivity (8.1 pT/). In addition, we also performed numerical calculations of the magnetic field distribution in the FGs to estimate the magnetic noise originating from the domain fluctuations in the material of the FGs. We anticipate many applications of the FG-OPM device such as the detection of micro-biological magnetic fields; the detection of magnetic nano-particles; and non-destructive testing. From our theoretical estimate, an FG-OPM could detect the magnetic field of a single neuron, which would be an important milestone in neuroscience. PMID:27103463

  14. On the importance of cavity-length and heat dissipation in GaN-based vertical-cavity surface-emitting lasers

    PubMed Central

    Liu, W. J.; Hu, X. L.; Ying, L. Y.; Chen, S. Q.; Zhang, J. Y.; Akiyama, H.; Cai, Z. P.; Zhang, B. P.

    2015-01-01

    Cavity-length dependence of the property of optically pumped GaN-based vertical-cavity surface-emitting lasers (VCSELs) with two dielectric distributed Bragg reflectors was investigated. The cavity lengths were well controlled by employing etching with inductively coupled plasma and chemical mechanical polishing. It was found that the lasing characteristics including threshold, slope efficiency and spontaneous emission coupling factor were substantially improved with reducing the cavity length. In comparison with the device pumped by a 400 nm pulsed laser, the lasing spectrum was featured by a red shift and simultaneous broadening with increasing the pumping energy of a 355 nm pulsed laser. Moreover, the lasing threshold was much higher when pumped by a 355 nm pulsed laser. These were explained by taking into account of the significant heating effect under 355 nm pumping. Our results demonstrate that a short cavity length and good heat-dissipation are essential to GaN-based VCSELs. PMID:25873327

  15. Towards loss compensated and lasing terahertz metamaterials based on optically pumped graphene.

    PubMed

    Weis, P; Garcia-Pomar, J L; Rahm, M

    2014-04-07

    We evidence by numerical calculations that optically pumped graphene is suitable for compensating inherent loss in terahertz (THz) metamaterials. We calculate the complex conductivity of graphene under optical pumping and determine the proper conditions for terahertz amplification in single layer graphene. It is shown that amplification in graphene occurs up to room temperature for moderate pump intensities at telecommunication wavelength λ = 1.5 μm. Furthermore, we investigate the coupling between a plasmonic split ring resonator (SRR) metamaterial and optically pumped graphene at a temperature T = 77 K and a pump intensity I = 300 mW/mm(2). We find that the loss of a SRR metamaterial can be compensated by optically stimulated amplification in graphene. Moreover, we show that a hybrid material consisting of asymmetric split-ring resonators and optically pumped graphene can emit coherent THz radiation at minimum output power levels of 60 nW/mm(2).

  16. Eavesdropping in chaotic optical communication using the feedback length of an external-cavity laser as a key.

    PubMed

    Zhao, Qingchun; Wang, Yuncai; Wang, Anbang

    2009-06-20

    An external-cavity laser (ECL) operating in a chaotic state is usually used in a chaotic optical secure communication system and its feedback length (FL) is often regarded as an additional key. Our analyses show that an eavesdropper's (Eve) laser can synchronize with a transmitter (Alice) without any knowledge of the FL by simply increasing the injection strength. A sequence of a 1 Gbit/s nonreturn-to-zero message encoded by the FL as the key is successfully eavesdropped. The reason for the synchronization deviation between Alice's and Eve's lasers is given. Our results indicate that the FL as a key cannot enhance the security of chaotic optical communication using long-ECLs.

  17. Use of external cavity quantum cascade laser compliance voltage in real-time trace gas sensing of multiple chemicals

    NASA Astrophysics Data System (ADS)

    Phillips, Mark C.; Taubman, Matthew S.; Kriesel, Jason

    2015-01-01

    We describe a prototype trace gas sensor designed for real-time detection of multiple chemicals. The sensor uses an external cavity quantum cascade laser (ECQCL) swept over its tuning range of 940-1075 cm-1 (9.30-10.7 μm) at a 10 Hz repetition rate. The sensor was designed for operation in multiple modes, including gas sensing within a multi-pass Heriott cell and intracavity absorption sensing using the ECQCL compliance voltage. In addition, the ECQCL compliance voltage was used to reduce effects of long-term drifts in the ECQCL output power. The sensor was characterized for noise, drift, and detection of chemicals including ammonia, methanol, ethanol, isopropanol, Freon- 134a, Freon-152a, and diisopropyl methylphosphonate (DIMP). We also present use of the sensor for mobile detection of ammonia downwind of cattle facilities, in which concentrations were recorded at 1-s intervals.

  18. Demonstration of a rapidly-swept external cavity quantum cascade laser for rapid and sensitive quantification of chemical mixtures

    SciTech Connect

    Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.

    2016-02-13

    A rapidly-swept external cavity quantum cascade laser (ECQCL) system for fast open-path quantification of multiple chemicals and mixtures is presented. The ECQCL system is swept over its entire tuning range (>100 cm-1) at frequencies up to 200 Hz. At 200 Hz the wavelength tuning rate and spectral resolution are 2x104 cm-1/sec and < 0.2 cm-1, respectively. The capability of the current system to quantify changes in chemical concentrations on millesecond timescales is demonstrated at atmospheric pressure using an open-path multi-pass cell. The detection limits for chemicals ranged from ppb to ppm levels depending on the absorption cross-section.

  19. Analytical model for low finesse, external cavity, fiber Fabry-Perot interferometers including multiple reflections and angular misalignment.

    PubMed

    Wilkinson, Paul R; Pratt, Jon R

    2011-08-10

    We present an analytical model for single mode, multiply reflected, external cavity, optical fiber Fabry-Perot interferometers in the low finesse regime using simple geometry and the Gaussian beam approximation. The multiple reflection model predicts attenuation of the peak-to-peak interference as the fiber to mirror distance approaches zero, as well as fringe asymmetry in the presence of nonabsorbing mirrors. A series of experiments are conducted in which a series of fiber Fabry-Perot cavities are constructed using uncoated, single mode glass fibers, and mirrors of varying reflectivity. The cavity length is swept, and the predictions of the model are found to be in good agreement with the experimental interferograms.

  20. Atmospheric observations of multiple molecular species using ultra-high-resolution external cavity quantum cascade laser heterodyne radiometry.

    PubMed

    Weidmann, Damien; Tsai, Tracy; Macleod, Neil A; Wysocki, Gerard

    2011-06-01

    We demonstrate a widely tunable laser heterodyne radiometer operating in the thermal IR during an atmospheric observation campaign in the solar occultation viewing mode. An external cavity quantum cascade laser tunable within a range of 1120 to 1238 cm(-1) is used as the local oscillator (LO) of the instrument. Ultra-high-resolution (60 MHz or 0.002 cm(-1) transmission spectroscopy of several atmospheric species (water vapor, ozone, nitrous oxide, methane, and dichlorodifluoromethane) has been demonstrated within four precisely selected molecule-specific narrow spectral windows (∼1 cm(-1). Atmospheric transmission lines within each selected window were fully resolved through mode-hop-free continuous tuning of the LO frequency. Comparison measurements were made simultaneously with a high-resolution Fourier transform spectrometer to demonstrate the advantages of the laser heterodyne system for atmospheric sounding at high spectral and spatial resolutions. © 2011 Optical Society of America

  1. Demonstration of a rapidly-swept external cavity quantum cascade laser for rapid and sensitive quantification of chemical mixtures

    SciTech Connect

    Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.

    2016-02-13

    A rapidly-swept external cavity quantum cascade laser (ECQCL) system for fast open-path quantification of multiple chemicals and mixtures is presented. The ECQCL system is swept over its entire tuning range (>100 cm-1) at frequencies up to 200 Hz. At 200 Hz the wavelength tuning rate and spectral resolution are 2x104 cm-1/sec and < 0.2 cm-1, respectively. The capability of the current system to quantify changes in chemical concentrations on millesecond timescales is demonstrated at atmospheric pressure using an open-path multi-pass cell. The detection limits for chemicals ranged from ppb to ppm levels depending on the absorption cross-section.

  2. Single-mode, narrow-linewidth external cavity quantum cascade laser through optical feedback from a partial-reflector

    SciTech Connect

    Cendejas, Richard A.; Phillips, Mark C.; Myers, Tanya L.; Taubman, Matthew S.

    2010-11-30

    An external-cavity (EC) quantum cascade (QC) laser using optical feedback from a partial-reflector is reported. With this configuration, the otherwise multi-mode emission of a Fabry-Perot QC laser was made single-mode with optical output powers exceeding 40 mW. A mode-hop free tuning range of 2.46 cm-1 was achieved by synchronously tuning the EC length and QC laser current. The linewidth of the partial-reflector EC-QC laser was measured for integration times from 100 μs to 4 s, and compared to a distributed feedback QC laser. Linewidths as small as 480 kHz were recorded for the EC-QC laser

  3. Mode-hop-free electro-optically tuned external-cavity diode laser using volume Bragg grating and PLZT ceramic

    NASA Astrophysics Data System (ADS)

    Shen, Li; Ye, Qing; Cai, Haiwen; Qu, Ronghui

    2011-08-01

    We present a novel electro-optically tuned external-cavity diode laser (ECDL) that utilizes a volume Bragg grating (VBG) as the frequency selective feedback element and a piece of high electro-optic coefficient Lead Lanthanum Zirconate Titanate (PLZT) transparent ceramic as the frequency tuning element. By adjusting the voltage applied onto the PLZT, a single-mode frequency tuning range of 2.5GHz without mode hoping is achieved. The laser wavelength is around 810.0nm with the line-width of 19MHz and the side mode suppression ratio (SMSR) of 37dB. The advantages of combining a VBG and PLZT transparent electro-optic ceramic is that the laser frequency can be tuned finely and rapidly in a range of longitudinal mode spacing without mode hoping. Moreover, the wide-range coarse frequency tuning of 32.7 GHz can also be realized by changing the angle of incident light beam.

  4. Mode-hop-free electro-optically tuned external-cavity diode laser using volume Bragg grating and PLZT ceramic.

    PubMed

    Shen, Li; Ye, Qing; Cai, Haiwen; Qu, Ronghui

    2011-08-29

    We present a novel electro-optically tuned external-cavity diode laser (ECDL) that utilizes a volume Bragg grating (VBG) as the frequency selective feedback element and a piece of high electro-optic coefficient Lead Lanthanum Zirconate Titanate (PLZT) transparent ceramic as the frequency tuning element. By adjusting the voltage applied onto the PLZT, a single-mode frequency tuning range of 2.5GHz without mode hoping is achieved. The laser wavelength is around 810.0nm with the line-width of 19MHz and the side mode suppression ratio (SMSR) of 37dB. The advantages of combining a VBG and PLZT transparent electro-optic ceramic is that the laser frequency can be tuned finely and rapidly in a range of longitudinal mode spacing without mode hoping. Moreover, the wide-range coarse frequency tuning of 32.7 GHz can also be realized by changing the angle of incident light beam.

  5. Modulation-free frequency stabilization of external-cavity diode laser based on a phase-difference biased Sagnac interferometer.

    PubMed

    Wei, Fang; Chen, Dijun; Fang, Zujie; Cai, Haiwen; Qu, Ronghui

    2010-11-15

    We propose a modulation-free technique for frequency stabilization of an external-cavity diode laser (ECDL) by using a phase-difference biased Sagnac interferometer to produce dispersion spectroscopic error signals. A half-wave plate and a total internal reflection prism are inserted into the loop to provide a phase-difference bias between the clockwise and counterclockwise beams with perpendicular polarizations, instead of the previous method with misaligned optical paths. In the experiments, the frequency of the Littman-Metcalf configuration ECDL is locked at the transition of the Rb atomic vapor, and the frequency fluctuation is suppressed from 8 to less than 0.5 MHz peak to peak. It is shown that this scheme is simple, robust, low cost, and it shows promise for use in a variety of related applications.

  6. Widely tunable continuous-wave Raman laser in diatomic hydrogen pumped by an external-cavity diode laser.

    PubMed

    Meng, L S; Repasky, K S; Roos, P A; Carlsten, J L

    2000-04-01

    What is to the authors' knowledge the first experimental demonstration of a nonresonant cw Raman laser pumped by a tunable external-cavity diode laser (ECDL) is presented. The ECDL is phase-frequency locked to a high-finesse Raman laser cavity containing diatomic hydrogen (H(2)) by the Pound-Drever-Hall locking technique. The Stokes lasing threshold occurs at a pump power of 400 +/- 30 muW, and a maximum photon conversion efficiency of 12.0 +/- 1.3% is achieved at 1.6 mW of pump power. A 40-nm tuning range of the cw Stokes emission, 1174-1214 nm, is obtained by tuning of the wavelength of the ECDL pump source.

  7. Fixed-wavelength H2O absorption spectroscopy system enhanced by an on-board external-cavity diode laser

    NASA Astrophysics Data System (ADS)

    Brittelle, Mack S.; Simms, Jean M.; Sanders, Scott T.; Gord, James R.; Roy, Sukesh

    2016-03-01

    We describe a system designed to perform fixed-wavelength absorption spectroscopy of H2O vapor in practical combustion devices. The system includes seven wavelength-stabilized distributed feedback (WSDFB) lasers, each with a spectral accuracy of  ±1 MHz. An on-board external cavity diode laser (ECDL) that tunes 1320-1365 nm extends the capabilities of the system. Five system operation modes are described. In one mode, a sweep of the ECDL is used to monitor each WSDFB laser wavelength with an accuracy of  ±30 MHz. Demonstrations of fixed-wavelength thermometry at 10 kHz bandwidth in near-room-temperature gases are presented; one test reveals a temperature measurement error of ~0.43%.

  8. Green high-power tunable external-cavity GaN diode laser at 515  nm.

    PubMed

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2016-09-15

    A 480 mW green tunable diode laser system is demonstrated for the first time to our knowledge. The laser system is based on a GaN broad-area diode laser and Littrow external-cavity feedback. The green laser system is operated in two modes by switching the polarization direction of the laser beam incident on the grating. When the laser beam is p-polarized, an output power of 50 mW with a tunable range of 9.2 nm is achieved. When the laser beam is s-polarized, an output power of 480 mW with a tunable range of 2.1 nm is obtained. This constitutes the highest output power from a tunable green diode laser system.

  9. High-power dual-wavelength external-cavity diode laser based on tapered amplifier with tunable terahertz frequency difference.

    PubMed

    Chi, Mingjun; Jensen, Ole Bjarlin; Petersen, Paul Michael

    2011-07-15

    Tunable dual-wavelength operation of a diode laser system based on a tapered diode amplifier with double-Littrow external-cavity feedback is demonstrated around 800 nm. The two wavelengths can be tuned individually, and the frequency difference of the two wavelengths is tunable from 0.5 to 5.0 THz. An output power of 1.54 W is achieved with a frequency difference of 0.86 THz, the output power is higher than 1.3 W in the 5.0 THz range of frequency difference, and the amplified spontaneous emission intensity is more than 20 dB suppressed in the range of frequency difference. To our knowledge, this is the highest output power from a dual-wavelength diode laser system operating with tunable terahertz frequency difference. © 2011 Optical Society of America

  10. Broad area diode laser with on-chip transverse Bragg grating stabilized in an off-axis external cavity.

    PubMed

    Zink, Christof; Niebuhr, Mario; Jechow, Andreas; Heuer, Axel; Menzel, Ralf

    2014-06-16

    The emission characteristics of a novel, specially designed broad area diode laser (BAL) with on-chip transversal Bragg resonance (TBR) grating in lateral direction were investigated in an off-axis external cavity setup. The internal TBR grating defines a low loss transversal mode at a specific angle of incidence and a certain wavelength. By providing feedback at this specific angle with an external mirror, it is possible to select this low loss transverse mode and stabilize the BAL. Near diffraction limited emission with an almost single lobed far field pattern could be realized, in contrast to the double lobed far field pattern of similar setups using standard BALs or phase-locked diode laser arrays. Furthermore, we could achieve a narrow bandwidth emission with a simplified setup without external frequency selective elements.

  11. External cavity diode laser based photoacoustic detection of CO2 at 1.43 microm: the effect of molecular relaxation.

    PubMed

    Veres, Anikó; Bozóki, Zoltán; Mohácsi, Arpád; Szakáll, Miklós; Szabó, Gábor

    2003-08-01

    Photoacoustic spectroscopy, based on an external cavity diode laser operating at 1431 nm, was used for measuring CO2 concentration as a minority component in a gas mixture. By using N2 as a buffer gas, a molecular relaxation effect was observed, which influenced both the amplitude and the phase of the measured photoacoustic signal and consequently reduced the sensitivity of the PA system. This molecular relaxation effect could be suppressed by adding water vapor of a constant and relatively high (approximately 4%) concentration to the gas sample. In parallel with this, the arising spectral interference between H2O and CO2 necessitated the development of a simple yet efficient signal analysis method, which increased the sensitivity of the system by more than one order of magnitude and accordingly reduced the minimum detectable CO2 concentration down to approximately 1000 ppm.

  12. Single-mode, narrow-linewidth external cavity quantum cascade laser through optical feedback from a partial-reflector.

    PubMed

    Cendejas, Richard A; Phillips, Mark C; Myers, Tanya L; Taubman, Matthew S

    2010-12-06

    An external-cavity (EC) quantum cascade (QC) laser using optical feedback from a partial-reflector is reported. With this configuration, the otherwise multi-mode emission of a Fabry-Perot QC laser was made single-mode with optical output powers exceeding 40 mW. A mode-hop free tuning range of 2.46 cm(-1) was achieved by synchronously tuning the EC length and QC laser current. The linewidth of the partial-reflector EC-QC laser was measured for integration times from 100 μs to 4 seconds, and compared to a distributed feedback QC laser. Linewidths as small as 480 kHz were recorded for the EC-QC laser.

  13. Widely tunable, narrow linewidth external-cavity gain chip laser for spectroscopy between 1.0 - 1.1 µm.

    PubMed

    Shin, Dong K; Henson, Bryce M; Khakimov, Roman I; Ross, Jacob A; Dedman, Colin J; Hodgman, Sean S; Baldwin, Kenneth G H; Truscott, Andrew G

    2016-11-28

    We have developed and characterised a stable, narrow linewidth external-cavity laser (ECL) tunable over 100 nm around 1080 nm, using a single-angled-facet gain chip. We propose the ECL as a low-cost, high-performance alternative to fibre and diode lasers in this wavelength range and demonstrate its capability through the spectroscopy of metastable helium. Within the coarse tuning range, the wavelength can be continuously tuned over 30 pm (7.8 GHz) without mode-hopping and modulated with bandwidths up to 3 kHz (piezo) and 37(3) kHz (current). The spectral linewidth of the free-running ECL was measured to be 22(2) kHz (Gaussian) and 4.2(3) kHz (Lorentzian) over 22.5 ms, while a long-term frequency stability better than 40(20) kHz over 11 hours was observed when locked to an atomic reference.

  14. Operation of a frequency-narrowed high-beam quality broad-area laser by a passively stabilized external cavity technique

    NASA Astrophysics Data System (ADS)

    Bayram, S. B.; Coons, R. W.

    2007-11-01

    The average spectral bandwidth of a 2W broad-area diode laser was narrowed to 5GHz with wavelength tunability of up to 12nm at a center wavelength of 790nm with the use of a Littman-Metcalf external cavity in a displaced configuration. The use of lens and combined lens-laser transformation systems allowed precise alignment of the beam shaping optics, which led to significant improvements of the beam quality and an enhanced suppression of the free-running laser modes. We characterize the spatial beam quality of our external cavity diode laser by measuring the M2 quality factor and relate this to our measured bandwidths. Our external cavity can be configured over a range of cavity lengths and is modular in design, enabling access to a broad frequency spectrum for a wide range of applications that require high-power, narrow bandwidth operation.

  15. Measurement of nitrous acid (HONO) by external-cavity quantum cascade laser based quartz-enhanced photoacoustic absorption spectroscopy

    NASA Astrophysics Data System (ADS)

    Yi, Hongming; Maamary, Rabih; Gao, Xiaoming; Sigrist, Markus W.; Fertein, Eric; Chen, Weidong

    2016-04-01

    Spectroscopic detection of short-lived gaseous nitrous acid (HONO) at 1254.85 cm-1 was realized by off-beam coupled quartz-enhanced photoacoustic spectroscopy (QEPAS) in conjunction with an external cavity quantum cascade lasers (EC-QCL). High sensitivity monitoring of HONO was performed within a very small gas-sample volume (of ~40 mm3) allowing a significant reduction (of about 4 orders of magnitude) of air sampling residence time which is highly desired for accurate quantification of chemically reactive short-lived species. Calibration of the developed QEPAS-based HONO sensor was carried out by means of lab-generated HONO samples whose concentrations were determined by simultaneous measurements of direct HONO absorption spectra in a 109.5 m multipass cell using a distributed feedback (DBF) QCL. A minimum detection limit (MDL @ SNR=1) of 66 ppbv HONO was achieved at 70 mbar using a laser output power of 50 mW and 1 s integration time, which corresponded to a normalized noise equivalent absorption coefficient of 3.6×10-8 cm-1.W/Hz1/2. This MDL was down to 7 ppbv at the optimal integration time of 150 s. The corresponding minimum detected absorption coefficient (SNR=1) is ~1.1×10-7 cm-1 (MDL: ~3 ppbv) in 1 s and ~1.1×10-8 cm-1 (MDL~330 pptv) in 150 s, respectively, with 1 W laser power. Acknowledgements The authors acknowledge financial supports from the CaPPA project (ANR-10-LABX-005) and the CPER CLIMIBIO program. References H. Yi, R. Maamary, X. Gao, M. W. Sigrist, E. Fertein, W. Chen, "Short-lived species detection of nitrous acid by external-cavity quantum cascade laser based quartz-enhanced photoacoustic absorption spectroscopy", Appl. Phys. Lett. 106 (2015) 101109

  16. Optically Pumped Nuclear Magnetic Resonance in the Quantum Hall Regimes

    NASA Astrophysics Data System (ADS)

    Barrett, Sean E.

    1998-03-01

    Optical pumping enables the direct detection of the nuclear magnetic resonance signal of ^71Ga nuclei located in an electron doped GaAs quantum well.footnote S. E. Barrett et al., Phys. Rev. Lett. 72, 1368 (1994) This OPNMR technique was previously used to measure the Knight shift (K_S)footnote S. E. Barrett et al., Phys. Rev. Lett. 74, 5112 (1995) and spin-lattice relaxation time (T_1)footnote R. Tycko et al., Science 268, 1460 (1995) near Landau level filling ν=1, which provided the first experimental support for the theoretical predictionsfootnote S. L. Sondhi et al., Phys. Rev. B 47, 16419 (1993); H. A. Fertig et al., Phys. Rev. B 50, 11018 (1994) that the charged excitations of the ν = 1 ground state are novel spin textures called skyrmions. We have recently demonstrated that OPNMR is possible in fields up to B=12 Tesla, and temperatures down to T= 0.3 K, making it a viable new probe of the Fractional Quantum Hall Regime. In this talk we will present our latest OPNMR measurements near Landau level filling ν=1/3, which include the first direct measurement of the electron spin polarization at ν=1/3. The spin polarization drops as the filling factor is varied away from ν=1/3, indicating that the quasiparticles and quasiholes are not fully spin-polarized. We will also show how the NMR lineshape away from ν=1/3 changes dramatically at low temperatures, which is due to slowing of the electron dynamics, and a reduction in the motional narrowing of the NMR line. The current understanding of these results will be discussed.

  17. Temperature-Ramped 129Xe Spin-Exchange Optical Pumping

    PubMed Central

    2015-01-01

    We describe temperature-ramped spin-exchange optical pumping (TR-SEOP) in an automated high-throughput batch-mode 129Xe hyperpolarizer utilizing three key temperature regimes: (i) “hot”—where the 129Xe hyperpolarization rate is maximal, (ii) “warm”—where the 129Xe hyperpolarization approaches unity, and (iii) “cool”—where hyperpolarized 129Xe gas is transferred into a Tedlar bag with low Rb content (<5 ng per ∼1 L dose) suitable for human imaging applications. Unlike with the conventional approach of batch-mode SEOP, here all three temperature regimes may be operated under continuous high-power (170 W) laser irradiation, and hyperpolarized 129Xe gas is delivered without the need for a cryocollection step. The variable-temperature approach increased the SEOP rate by more than 2-fold compared to the constant-temperature polarization rate (e.g., giving effective values for the exponential buildup constant γSEOP of 62.5 ± 3.7 × 10–3 min–1 vs 29.9 ± 1.2 × 10–3 min–1) while achieving nearly the same maximum %PXe value (88.0 ± 0.8% vs 90.1% ± 0.8%, for a 500 Torr (67 kPa) Xe cell loading—corresponding to nuclear magnetic resonance/magnetic resonance imaging (NMR/MRI) enhancements of ∼3.1 × 105 and ∼2.32 × 108 at the relevant fields for clinical imaging and HP 129Xe production of 3 T and 4 mT, respectively); moreover, the intercycle “dead” time was also significantly decreased. The higher-throughput TR-SEOP approach can be implemented without sacrificing the level of 129Xe hyperpolarization or the experimental stability for automation—making this approach beneficial for improving the overall 129Xe production rate in clinical settings. PMID:25008290

  18. Temperature-ramped (129)Xe spin-exchange optical pumping.

    PubMed

    Nikolaou, Panayiotis; Coffey, Aaron M; Barlow, Michael J; Rosen, Matthew S; Goodson, Boyd M; Chekmenev, Eduard Y

    2014-08-19

    We describe temperature-ramped spin-exchange optical pumping (TR-SEOP) in an automated high-throughput batch-mode (129)Xe hyperpolarizer utilizing three key temperature regimes: (i) "hot"-where the (129)Xe hyperpolarization rate is maximal, (ii) "warm"-where the (129)Xe hyperpolarization approaches unity, and (iii) "cool"-where hyperpolarized (129)Xe gas is transferred into a Tedlar bag with low Rb content (<5 ng per ∼1 L dose) suitable for human imaging applications. Unlike with the conventional approach of batch-mode SEOP, here all three temperature regimes may be operated under continuous high-power (170 W) laser irradiation, and hyperpolarized (129)Xe gas is delivered without the need for a cryocollection step. The variable-temperature approach increased the SEOP rate by more than 2-fold compared to the constant-temperature polarization rate (e.g., giving effective values for the exponential buildup constant γSEOP of 62.5 ± 3.7 × 10(-3) min(-1) vs 29.9 ± 1.2 × 10(-3) min(-1)) while achieving nearly the same maximum %PXe value (88.0 ± 0.8% vs 90.1% ± 0.8%, for a 500 Torr (67 kPa) Xe cell loading-corresponding to nuclear magnetic resonance/magnetic resonance imaging (NMR/MRI) enhancements of ∼3.1 × 10(5) and ∼2.32 × 10(8) at the relevant fields for clinical imaging and HP (129)Xe production of 3 T and 4 mT, respectively); moreover, the intercycle "dead" time was also significantly decreased. The higher-throughput TR-SEOP approach can be implemented without sacrificing the level of (129)Xe hyperpolarization or the experimental stability for automation-making this approach beneficial for improving the overall (129)Xe production rate in clinical settings.

  19. Investigation of double-mode operation and fast fine tuning properties of a grating-coupled external cavity diode laser configuration

    NASA Astrophysics Data System (ADS)

    Bayrakli, Ismail

    2017-01-01

    Double-mode operation and fast piezo fine tuning properties of a gain chip on a thermoelectric cooler in an external cavity are investigated. A widely course double-mode tuning range of 120 nm for the spectral range between 1470 and 1590 nm is achieved by rotating the diffraction gratings forming a double Littrow-type configuration. A fast piezo fine tuning range over 7cm-1 (1.5 nm, 210 GHz) in a single-mode operation is obtained by scanning the external cavity length with scan rates up to 0.5 kHz.

  20. GaN photonic-crystal surface-emitting laser at blue-violet wavelengths.

    PubMed

    Matsubara, Hideki; Yoshimoto, Susumu; Saito, Hirohisa; Jianglin, Yue; Tanaka, Yoshinori; Noda, Susumu

    2008-01-25

    Shorter-wavelength surface-emitting laser sources are important for a variety of fields, including photonics, information processing, and biology. We report on the creation of a current-driven blue-violet photonic-crystal surface-emitting laser. We have developed a fabrication method, named "air holes retained over growth," in order to construct a two-dimensional gallium nitride (GaN)/air photonic-crystal structure. The resulting periodic structure has a photonic-crystal band-edge effect sufficient for the successful operation of a current-injection surface-emitting laser. This represents an important step in the development of laser sources that could be focused to a size much less than the wavelength and be integrated two-dimensionally at such short wavelengths.

  1. Optical pump terahertz probe studies of semiconducting polymers

    NASA Astrophysics Data System (ADS)

    Cunningham, Paul D.

    Optical-pump terahertz-probe spectroscopy (OPTP) has been applied to study charge generation, transport and the evolution of the photo-induced excited states in thin film organic semiconductors, with emphasis on their relevance to photovoltaic technology. In these experiments the response of the photoexcited material to the AC electric field of a terahertz (THz) pulse was measured. From this response, the evolution of the complex conductivity in the far-infrared was monitored. OPTP presents advantages over other techniques by being an all-optical probe of the complex conductivity over nanometer scale distances with sub-picosecond resolution and exhibits particular sensitivity to carrier scattering rates, which typically lay in the THz range. Conductivity models were applied to the extracted conductivity curves in order to determine technologically relevant quantities like the charge carrier mobility and external quantum yield of charge carrier generation. We observed charge carriers generated on a subpicosecond time scale in thin films of polyhexylthiophene (P3HT). Through application of the Drude-Smith model (DSM) over the 0-2 THz band, we determined a room temperature intrinsic mobility of about 30 cm2/Vs. The temperature dependence of the conductivity dynamics showed signs of thermally activated polaron hopping influenced by torsional disorder. Both above and below gap excitation resulted in similar dynamics, showing that the majority of carriers recombine within 1 ps. We were able to observe charge transfer occurring on a sub-ps timescale to the soluble fullerene, PCBM, for both excited states, demonstrating that narrow gap polymers can be blended with PCBM for photovoltaic applications. We observed charge carrier generated on a sub-ps time scale in thin amorphous films of metalated polymers. The time evolution of the conductivity showed that charge carriers recombine and only excitons persist after 100 ps. This characteristic appears to be common to amorphous

  2. Ionisation Mechanisms in AN Optically Pumped Mercury Vapour.

    NASA Astrophysics Data System (ADS)

    Counsell, G. F.

    Available from UMI in association with The British Library. Requires signed TDF. A plasma formed in a mercury vapour by optical pumping at visible and U.V. wavelengths from a high current mercury discharge, has been investigated with a view to gaining an understanding of the ionisation processes giving rise to the plasma. These were believed to generate both atomic and molecular ions. The results of this work have applications in the fields of fluorescent lighting and the mercury-nitrogen laser. The plasma was studied with a variety of diagnostic tools. Electron number densities and temperatures were determined using Langmuir probes operating in the orbital motion limited regime. Populations of the 6^3 P triplet states, believed to be the only significantly populated excited states in the plasma, were determined using absorption spectroscopy. Lastly, a quadrupole mass spectrometer, coupled to the plasma with an electrostatic ion transport system, was used to investigate the flux of atomic and molecular ions to a body at floating potential in the plasma. The Langmuir probe and absorption spectroscopy results were included into a model describing ion motions in the plasma, based around the ion fluid equations and including source terms for the generation of atomic and molecular ions, both by electron impact and by binary collisions of atoms in the 6^3P triplet states. Where possible, ionisation rats in the model were calculated using published cross-sections. However, for the heavy body collisional processes in particular, many of these are unknown. Consequently, an attempt was made to determine these cross-sections by generating results from the model that could be compared to experimental measurements of the atomic and molecular ion fluxes to the mass spectrometer. A number of computational experiments were carried out, varying the cross-sections until a good fit to the experimental measurements was achieved. Using this technique it was possible to estimate cross

  3. GaN-based surface-emitting lasers using high-contrast grating

    NASA Astrophysics Data System (ADS)

    Lu, Tien-Chang; Wang, Shing-Chung; Wu, Tzeng-Tsong; Wu, Shu-Hsien; Syu, Yu-Cheng

    2014-02-01

    GaN-based surface-emitting lasers (SELs) using high contrast grating (HCG) with AlN/GaN distributed Bragg reflectors were reported. The laser device achieved a threshold energy density of about 0.56 mJ/cm2 and the lasing wavelength was at 393.6 nm with a high degree of polarization of 73% at room temperature. The resonant mode and polarization characteristics matched to the theoretical prediction. GaN-based SELs using HCG supported by the Fano resonance can be potential for development of blue surface emitting laser sources

  4. 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.

  5. Lateral cavity photonic crystal surface emitting laser based on commercial epitaxial wafer.

    PubMed

    Wang, Yufei; Qu, Hongwei; Zhou, Wenjun; Qi, Aiyi; Zhang, Jianxin; Liu, Lei; Zheng, Wanhua

    2013-04-08

    A lateral cavity photonic crystal surface emitting laser (LC-PCSEL) with airholes of cone-like shape etched near to the active layer is fabricated. It employs only a simple commercial epitaxial wafer without DBR and needs no wafer bonding technique. Surface emitting lasing action at 1575 nm with power of 1.8 mW is observed at room temperature, providing potential values for mass production of electrically driven PCSELs with low cost. Additionally, Fano resonance is utilized to analyze aperture equivalence of PC, and energy distribution in simplified laser structure is simulated to show oscillation and transmission characteristics of laser.

  6. Broadband Mid-Infrared Stand-Off Reflection-Absorption Spectroscopy Using a Pulsed External Cavity Quantum Cascade Laser.

    PubMed

    Liu, Xunchen; Chae, Inseok; Miriyala, Naresh; Lee, Dongkyu; Thundat, Thomas; Kim, Seonghwan

    2017-07-01

    Broadband mid-infrared molecular spectroscopy is essential for detection and identification of many chemicals and materials. In this report, we present stand-off mid-infrared spectra of 1,3,5-trinitro-1,3,5-triazine or cyclotrimethylene trinitramine (RDX) residues on a stainless-steel surface measured by a broadband external cavity quantum cascade laser (QCL) system. The pulsed QCL is continuously scanned over 800 cm(-1) in the molecular fingerprint region and the amplitude of the reflection signal is measured by either a boxcar-averager-based scheme or a lock-in-amplifier-based scheme with 1 MHz and 100 kHz quartz crystal oscillators. The main background noise is due to the laser source instability and is around 0.1% of normalized intensity. The direct absorption spectra have linewidth resolution around 0.1 cm(-1) and peak height sensitivity around 10(-2) due to baseline interference fringes. Stand-off detection of 5-50 µg/cm(2) of RDX trace adsorbed on a stainless steel surface at the distance of 5 m is presented.

  7. Sensitive Raman gas analysis using a 500 mW external cavity diode laser at 410 nm

    NASA Astrophysics Data System (ADS)

    Li, Bin; Luo, Shiwen; Yu, Anlan; Gao, Jun; Sun, Pengfei; Wang, Xinbing; Zuo, Duluo

    2017-09-01

    Sensitive Raman gas analysis based on a home-made high power 410 nm Littrow-arranged external cavity diode laser (ECDL) and a parabolic sample cell is presented. Using a commercially available violet laser diode and a reflective holographic grating, the ECDL achieves a maximum output power of 505 mW with line-width about 50 pm. Spontaneous Raman scattering of ambient air is acquired with this ECDL, in which an imaging Raman spectrometer is applied. Strong Raman signals of O2, N2 and H2O are observed with 1 s exposure time; a limit of detection (LOD) of CO2 about 210 ppm is achieved with an exposure time of 100 s and a 3.5-fold enhancement to the signal level is also demonstrated compared with a 532 nm green laser with the same exciting power. The results show that violet diode laser can be an attractive excitation source for Raman gas analysis.

  8. Simple detuning method for low-chirp operation in polymer-based tunable external-cavity lasers.

    PubMed

    Choi, Byung-Seok; Jeong, Jong Sool; Lee, Hak-Kyu; Chung, Yun C

    2015-11-30

    We propose and demonstrate a simple detuning method for the low-chirp operation of a polymer-based tunable external-cavity laser (ECL). To ensure the low-chirp operation of this directly-modulated ECL, we first obtain the optimum values of the heater current applied to the polymer Bragg grating reflector (PBR) and the operating temperature of this ECL. For this purpose, we sweep the current applied to the phase control heater until the peak output power measured from the high-reflection (HR) coated facet reaches the minimum value. We then operate this ECL with minimum chirp by tuning the lasing mode to the longer wavelength limit of the stable operation region. This is because the detuned loading effect is maximized at this limit as the in-phase condition between the lights reflected from the PBR and anti-reflection (AR) coated facet of the gain medium is satisfied. Thus, by using this method together with conventional wavelength-locking algorithm, we can operate this ECL with minimum chirp at any wavelength.

  9. Influence of transform-lens focal length on spectral beam combining in an external cavity with a microlens array

    NASA Astrophysics Data System (ADS)

    Zhan, Sheng-bao; Wu, Zhuo-liang; He, Feng; Zhang, Jie; You, Jian-cun; Ma, Ye-wan

    2017-03-01

    An experimental system of spectral beam combining of 3 large-mode-area double-clad fiber lasers has been built on the basis of an external cavity with a microlens array. The analysis models of coupling and combining efficiency, as well as beam quality were established. According to the models, the influences of focal length of transform lens on the coupling, combining efficiency, as well as beam quality were analyzed. The results show that the longer focal length of transform lens increases the number of combined emitters, while hardly affects the combining efficiency. In the tunable experiment of individual fiber laser, the laser can be tuned in a range of 40.62 nm for using transform lens with focal length of 50 mm, slightly wider than that for another one with focal length of 100 mm (40.36 nm). In the combining experiment of three fiber lasers, the measured combining efficiency for the transform lens with focal length of 50 mm was about 77.0%, with the output power of about 1.01 W, and the beam quality factor (Mx2) of 1.318. For another one with focal length of 100 mm, the measured combining efficiency was about 83.3%, with the output power of about 1.09 W, and the beam quality factor (Mx2) of 1.312.

  10. Standoff detection of explosives and chemical agents using broadly tuned external-cavity quantum cascade lasers (EC-QCLs)

    NASA Astrophysics Data System (ADS)

    Takeuchi, Eric B.; Rayner, Timothy; Weida, Miles; Crivello, Salvatore; Day, Timothy

    2007-10-01

    Civilian soft targets such as transportation systems are being targeted by terrorists using IEDs and suicide bombers. Having the capability to remotely detect explosives, precursors and other chemicals would enable these assets to be protected with minimal interruption of the flow of commerce. Mid-IR laser technology offers the potential to detect explosives and other chemicals in real-time and from a safe standoff distance. While many of these agents possess "fingerprint" signatures in the mid-IR (i.e. in the 3-20 micron regime), their effective interrogation by a practical, field-deployable system has been limited by size, complexity, reliability and cost constraints of the base laser technology. Daylight Solutions has addressed these shortcomings by developing compact, portable, broadly tunable mid-IR laser sources based upon external-cavity quantum cascade technology. This technology is now being applied by Daylight in system level architectures for standoff and remote detection of explosives, precursors and chemical agents. Several of these architectures and predicted levels of performance will be presented.

  11. Monolithic integration of MQW wavelength tunable DBR lasers with external cavity electroabsorption modulators by selective-area MOCVD

    NASA Astrophysics Data System (ADS)

    Lammert, Robert M.; Smith, Gary M.; Hughes, J. S.; Osowski, Mark L.; Jones, A. M.; Coleman, James J.

    1997-01-01

    The design and operation of multiple-quantum well (MQW) wavelength tunable distributed Bragg reflector (DBR) lasers with nonabsorbing gratings and monolithically integrated external cavity electroabsorption modulators fabricated by selective-area metal-organic chemical vapor deposition (MOCVD) are presented. Uncoated devices exhibit cw threshold currents as low as 10.5 mA with slope efficiencies of 0.21 W/A from the laser facet and 0.06 W/A from the modulator facet. After the application of facet coatings, slope efficiencies from the modulator facet increase to 0.14 W/A. Wavelength tuning of 7 nm is obtained by injection current heating of the DBR section. These devices exhibit extinction ratios of 18 dB from the modulator facet at a low modulator bias of 1 V, when measured with a broad-area detector. When coupled to a singlemode fiber, these devices exhibit high extinction ratios of 40 dB at a modulator bias of 1.25 V. Photo-generated current versus optical power plots indicate that the extinction ratios are not limited by carrier build- up in the modulator quantum wells.

  12. Design and Performance of a Sensor System for Detection of Multiple Chemicals Using an External Cavity Quantum Cascade Laser

    SciTech Connect

    Phillips, Mark C.; Taubman, Matthew S.; Bernacki, Bruce E.; Cannon, Bret D.; Schiffern, John T.; Myers, Tanya L.

    2010-01-23

    We describe the performance of a sensor system designed for simultaneous detection of multiple chemicals with both broad and narrow absorption features. The sensor system consists of a broadly tunable external cavity quantum cascade laser (ECQCL), multi-pass Herriott cell, and custom low-noise electronics. The ECQCL features a rapid wavelength tuning rate of 2265 cm 1/s (15660 nm/s) over its tuning range of 1150-1270 cm 1 (7.87-8.70 μm), which permits detection of molecules with broad absorption features and dynamic concentrations, while the 0.2 cm-1 spectral resolution of the ECQCL system allows measurement of small molecules with atmospherically broadened absorption lines. High-speed amplitude modulation and low-noise electronics are used to improve the ECQCL performance for direct absorption measurements. We demonstrate simultaneous detection of Freon-134a (1,1,1,2-tetrafluoroethane), ammonia (NH3), and nitrous oxide (N2O) at low-ppb concentrations in field measurements of atmospheric chemical releases from a point source.

  13. Wavenumber Measurements of CO(2) Transitions in 1.5-µm Atmospheric Window Using an External-Cavity Diode Laser.

    PubMed

    Chou; Lin; Shy

    2001-01-01

    Using an external-cavity diode laser (ECDL) as the light source, we have observed the spectrum of CO(2) in the 1.5-µm atmospheric window including the (30(0)1)(I) <-- (00(0)0) and (31(1)1)(I) <-- (01(1)0)(I) bands. Good signal-to-noise ratio allowed us to lock the frequency of our ECDL to the absorption line centers. Wavenumber measurements of the transitions with accuracy about 6.6 x 10(-4) cm(-1) are made with the help of a precision wavemeter calibrated to the accurate C(2)H(2) frequency references in the 1.5-µm wavelength region. Molecular constants are obtained by making the least-squares fits of the measured transition wavenumbers. The rotational and centrifugal distortion constants are consistent with the previous results using high-resolution Fourier transform spectroscopy. However, the band centers are different with previous results by several thousandth reciprocal centimeters. Copyright 2001 Academic Press.

  14. Periodic error characterization in commercial heterodyne interferometer using an external cavity diode laser based Fabry-Perot interferometer

    NASA Astrophysics Data System (ADS)

    Zhu, Minhao; Wei, Haoyun; Li, Yan

    2014-07-01

    Periodic error is a main error source that limits the measurement accuracy in heterodyne laser interferometry. An external cavity diode laser (ECDL) based Fabry-Perot (F-P) interferometer referenced to an optical frequency comb (OFC) is proposed to characterize the periodic error in heterodyne interferometers. The Pound-Drever-Hall locking technique is employed to lock the tracking ECDL frequency to the resonance of a high finesse F-P cavity. The frequency of a reference ECDL is locked to a selected mode of an OFC to generate a stable single optical frequency. The frequency change of the tracking ECDL induced by the cavity displacement is measured by beating with the reference ECDL locked to the OFC. Experiments show that the F-P interferometer system has a displacement resolution of 1.96 pm. We compared the measurement results of our system with a commercial plane mirror heterodyne interferometer. The period if the periodic error is about half wavelength, with an error amplitude of 4.8 nm.

  15. 400mW output power at 445 nm with narrowband emission from an external cavity diode laser system

    NASA Astrophysics Data System (ADS)

    Ruhnke, Norman; Müller, André; Eppich, Bernd; Maiwald, Martin; Sumpf, Bernd; Erbert, Götz; Tränkle, Günther

    2015-03-01

    Recently, high-power broad-area laser diodes based on GaN with output powers beyond 1 W have become available. However, their broad spectral emission limits their applicability. Due to a lack of internal grating technology for GaN devices, narrowband emission with several hundreds of milliwatts in the blue-green spectral range has not been achieved with laser diodes thus far. In this work, a high-power external cavity diode laser (ECDL) system at 445 nm is presented. The system is based on a commercially available broad-area GaN laser diode and a surface diffraction grating in Littrow configuration for optical feedback. Using this configuration an output power of 400 mW with a reduced spectral emission bandwidth of 20 pm (FWHM) with a side-mode suppression ratio larger than 40 dB is obtained. With the above presented optical output power and narrowband laser emission at 445 nm, the ECDL is well suited as a pump light source for nonlinear frequency conversion into the deep ultraviolet spectral range.

  16. Dual-pumped nondegenerate four-wave mixing in semiconductor laser with a built-in external cavity

    NASA Astrophysics Data System (ADS)

    Wu, Jian-Wei; Qiu, Qi; Hyub Won, Yong

    2017-04-01

    In this paper, a semiconductor laser system consisting of a conventional multimode Fabry-Pérot laser diode with a built-in external cavity is presented and demonstrated. More than two resonance modes, whose peak levels are significantly higher than other residual modes, are simultaneously supported and output by adjusting the bias current and operating temperature of the active region. Based on this device, dual-pumped nondegenerate four-wave mixing—in which two pump waves and a single signal wave are simultaneously fed into the laser, and the injection power and wavelength of the injected pump and signal waves are changed—is observed and discussed thoroughly. The results show that while the wavelengths of pump wave A and signal wave S are kept constant, the other pump wave B jumps from about 1535 nm to 1578 nm, generating conversion signals with changed wavelengths. The achieved conversion bandwidth between the primary signal and the converted signal waves is broadly tunable in the range of several terahertz frequencies. Both the conversion efficiency and optical signal-to-noise ratio of the newly generated conversion signals are adopted to evaluate the performance of the proposed four-wave mixing process, and are strongly dependent on the wavelength and power of the injected waves. Here, the attained maximum conversion efficiency and optical signal-to-noise ratio are close to -22 dB and 15 dB, respectively.

  17. Advanced technology of GaN based tunable violet laser with external cavity for holographic data storage

    NASA Astrophysics Data System (ADS)

    Mori, Naoki; Dejima, Norihiro; Higashiura, Atsushi; Omori, Masaki; Higuchi, Yu

    2016-09-01

    We successfully completed the development of a GaN based Tunable laser for Tapestry holographic data storage through collaborative research with InPhase Technologies in 2010. After the collaborative research, with the aim to achieve further advance development for commercial storage use, we have continued to improve the laser characteristics, especially coherence property and high optical output power are significant issues for holographic data storage. Longitudinal single mode lasing is one of most important property in hologram recording; therefore we addressed to optimize laser diode structure for external cavity laser. In parallel to that, we have reviewed not only a Laser diode structure but also laser drive processing, and have successfully developed a function. In the case of performing high visibility hologram recording, prior to exposing to medium, both the laser driving current and the wavelength are slightly adjusted to achieve single mode lasing. We call this function "Mode Stabilizer". Mode Stabilizer can automatically execute the adjustments in combination with an internal mode sensor for visibility sensing. This function is advantageous in that erroneous page-recording can be avoided. Moreover, we achieved high optical output power of 100 mW increased from conventional 45 mW, by optimizing the device structure of GaN Laser diode. With this high optical output power, acceleration of recording bit rate becomes possible.

  18. Demonstration of a rapidly-swept external cavity quantum cascade laser for rapid and sensitive quantification of chemical mixtures

    NASA Astrophysics Data System (ADS)

    Brumfield, B. E.; Taubman, M. S.; Phillips, M. C.

    2016-02-01

    A rapidly-swept external-cavity quantum cascade laser with an open-path Herriott cell is used to quantify gas-phase chemical mixtures of D2O and HDO at an update rate of 40 Hz (25 ms measurement time). The chemical mixtures were generated by evaporating D2O liquid near the open-path Herriott cell, allowing the H/D exchange reaction with ambient H2O to produce HDO. Fluctuations in the ratio of D2O and HDO on timescales of < 1 s due to the combined effects of plume transport and the H/D exchange chemical reaction are observed. Based on a noise equivalent concentration analysis of the current system, detection limits of 147.0 ppbv and 151.6 ppbv in a 25 ms measurement time are estimated for D2O and HDO respectively with a 127 m optical path. These detection limits are reduced to 23.0 and 24.0 ppbv with a 1 s averaging time for D2O and HDO respectively. Detection limits < 200 ppbv are also estimated for N2O, F134A, CH4, Acetone, and SO2 for a 25 ms measurement time.

  19. External cavity based single mode Fabry-Pérot laser diode and its application towards all-optical digital circuits

    NASA Astrophysics Data System (ADS)

    Nakarmi, Bikash; Zhang, Xuping; Won, Yong Hyub

    2012-11-01

    We have proposed a novel approach of realizing all-optical logic gates and combinational circuit using external cavity based single mode Fabry-Pérot laser diodes (SMFP-LDs). Different techniques and critical parameters for injection locking the any one of the modes of SMFP-LDs are discussed. Taking consideration of wavelength detuning and input injected power, we have proposed and demonstrated multi-input injection locking, supporting beam injection locking with the conventional injection locking which are used for demonstrating different logic gates (NAND, AND, XNOR, XOR, NOT, NOR) and digital circuits (Half adder and Comparator). Since we have used SMFP-LDs, there is no requirement of additional probe beam and associated components as required by other optical technologies making the realization simple in configuration, cost effective and power efficient. Clear output waveforms, eye diagrams, risingfalling times and BER are presented to verify the proposed method. All-optical logic units and digital circuit are demonstrated at the data rate of 10 Gbps with the waveform of NRZ signal waveform and measured eye diagram and BER of the PRBS of 231-1 signal. The maximum power penalty among all demonstrated units is below 1.4 dB at the BER of 10-9.

  20. Rapid and sensitive quantification of isotopic mixtures using a rapidly-swept external cavity quantum cascade laser

    DOE PAGES

    Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.

    2016-05-23

    A rapidly-swept external-cavity quantum cascade laser with an open-path Herriott cell is used to quantify gas-phase chemical mixtures of D2O and HDO at a rate of 40 Hz (25-ms measurement time). The chemical mixtures were generated by evaporating D2O liquid near the open-path Herriott cell, allowing the H/D exchange reaction with ambient H2O to produce HDO. Fluctuations in the ratio of D2O and HDO on timescales of <1 s due to the combined effects of plume transport and the H/D exchange chemical reaction are observed. Noise-equivalent concentrations (1σ) (NEC) of 147.0 ppbv and 151.6 ppbv in a 25-ms measurement timemore » are determined for D2O and HDO, respectively, with a 127-m optical path. These NECs are improved to 23.0 and 24.0 ppbv with a 1-s averaging time for D2O and HDO, respectively. NECs <200 ppbv are also estimated for N2O, 1,1,1,2–tetrafluoroethane (F134A), CH4, acetone and SO2 for a 25-ms measurement time. Finally, the isotopic precision for measurement of the [D2O]/[HDO] concentration ratio of 33‰ and 5‰ is calculated for the current experimental conditions for measurement times of 25 ms and 1 s, respectively.« less

  1. Influence of spectral bandwidth limitations of tuneable external-cavity based quantum cascade laser systems for clinical biofluid analysis

    NASA Astrophysics Data System (ADS)

    Heise, H. Michael; Vahlsing, Thorsten

    2014-02-01

    In many publications, infrared spectroscopy excelled in multi-analyte assays of biofluids. Based on such technology, laboratory and point-of-care applications can be envisaged and most needed devices are for blood glucose measurements. Implementing strict glycemic control can reduce the risk of serious complications in both diabetic and critically ill patients. For this purpose, many different blood glucose monitoring techniques and insulin infusion strategies have been tested towards the realization of an artificial pancreas under closed loop control. However, for patient portable instrumentation current FTIR-spectrometers are still too bulky, which need replacement by devices that allow further miniaturization. Recently developed external cavity quantum cascade lasers (EC-QCL) are tuneable over about 200 cm-1, which however is still narrow, compared to the range accessible with FTIR-devices. In this work, we applied bandwidth constraints to previous FTIR-studies on blood plasma and dialysates of biofluids. For the clinically most important blood glucose no impairment was found using one laser only, provided that specific interferents were missing. Other analytes of interest, such as lactate and urea, indicated the need of broader tuneability over about 500 cm-1 with a second or third laser for a simultaneous glucose assay.

  2. Design of red-emitting external cavity diode laser module for high-slope efficiency and narrow bandwidth

    NASA Astrophysics Data System (ADS)

    Park, Jiyeon; Song, Hong Joo; Na, Hong Man; Lee, Jun Ho; Yun, Ilgu

    2015-09-01

    A red-emitting external cavity diode laser (ECDL) module was designed to increase the slope efficiency and reduce the bandwidth by tilting the solitary laser diode (LD) 90 deg. This tilt resulted in parallel polarization, which yielded high-slope efficiency and also produced a favorable geometry that minimized the area of the back-focused beam, thereby facilitating selection of a specific wavelength. A ray-tracing simulator was used to optimize optical parameters such as the back focal length of the collimating lens, the cavity length, and the grating's groove density. Based on the optimized structure, an ECDL module package was designed for thermal control by using autodisk computer-aided design tool. The resulting module obtained high-slope efficiency and narrow-bandwidth emission of red light, making it suitable for potential application as a light source for a commercial three-dimensional holographic system. The module achieved the narrow bandwidth of 80 pm and the slope efficiency of 0.81 W/A, which compared favorably with the output power of 0.8 to 0.9 W/A of commercial solitary LDs.

  3. Transverse Mode Dynamics and Ultrafast Modulation of Vertical-Cavity Surface-Emitting Lasers

    NASA Technical Reports Server (NTRS)

    Ning, Cun-Zheng; Biegel, Bryan A. (Technical Monitor)

    2002-01-01

    We show that multiple transverse mode dynamics of VCSELs (Vertical-Cavity Surface-Emitting Lasers) can be utilized to generate ultrafast intensity modulation at a frequency over 100 GHz, much higher than the relaxation oscillation frequency. Such multimode beating can be greatly enhanced by taking laser output from part of the output facet.

  4. Single orbital angular momentum mode emission from vertical cavity surface emitting laser by optical feedback

    NASA Astrophysics Data System (ADS)

    Toda, Y.; Moriya, H.; Shigematsu, K.; Yamane, K.; Morita, R.; Awaji, Y.

    2017-04-01

    Single angular momentum (OAM) mode emissions from a vertical cavity surface emitting laser (VCSEL) were demonstrated by an external optical feedback using computer generated holograms, which are optimized on the OAM modal gain of the free-running VCSEL. Side-mode suppression ratio of more than 23 dB was achieved for the OAM modes with l = +/-1.

  5. Highly uniform and reproducible vertical-cavity surface emitting lasers grown by metalorganic chemical vapor deposition

    SciTech Connect

    Hou, H.Q.; Chui, H.C.; Choquette, K.D.; Hammons, B.E.; Breiland, W.G.; Geib, K.M.

    1996-01-01

    We show that the uniformity of the lasing wavelength of vertical-cavity surface emitting lasers (VCSELs) can be as good as {plus_minus}0.3% across a entire 3 in. wafer in MOCVD growth with a similar run-to-run reproducibility.

  6. Method and device for remotely monitoring an area using a low peak power optical pump

    DOEpatents

    Woodruff, Steven D.; Mcintyre, Dustin L.; Jain, Jinesh C.

    2014-07-22

    A method and device for remotely monitoring an area using a low peak power optical pump comprising one or more pumping sources, one or more lasers; and an optical response analyzer. Each pumping source creates a pumping energy. The lasers each comprise a high reflectivity mirror, a laser media, an output coupler, and an output lens. Each laser media is made of a material that emits a lasing power when exposed to pumping energy. Each laser media is optically connected to and positioned between a corresponding high reflectivity mirror and output coupler along a pumping axis. Each output coupler is optically connected to a corresponding output lens along the pumping axis. The high reflectivity mirror of each laser is optically connected to an optical pumping source from the one or more optical pumping sources via an optical connection comprising one or more first optical fibers.

  7. Longitudinal Spin Relaxation of Optically Pumped Rubidium Atoms in Solid Parahydrogen.

    PubMed

    Upadhyay, Sunil; Kanagin, Andrew N; Hartzell, Chase; Christy, Tim; Arnott, W Patrick; Momose, Takamasa; Patterson, David; Weinstein, Jonathan D

    2016-10-21

    We have grown crystals of solid parahydrogen using a single closed-cycle cryostat. We have doped the crystals with rubidium atoms at densities on the order of 10^{17}  cm^{-3} and used optical pumping to polarize the spin state of the implanted atoms. The optical spectrum of the rubidium atoms shows larger broadening than previous work in which the rubidium was implanted in solid argon or neon. However, the optical pumping behavior is significantly improved, with both a larger optical pumping signal and a longer longitudinal relaxation time. The spin relaxation time shows a strong dependence on orthohydrogen impurity levels in the crystal, as well as the applied magnetic field. Current performance is comparable to state-of-the-art solid state systems at comparable spin densities, with potential for improvement at higher parahydrogen purities.

  8. Longitudinal Spin Relaxation of Optically Pumped Rubidium Atoms in Solid Parahydrogen

    NASA Astrophysics Data System (ADS)

    Upadhyay, Sunil; Kanagin, Andrew N.; Hartzell, Chase; Christy, Tim; Arnott, W. Patrick; Momose, Takamasa; Patterson, David; Weinstein, Jonathan D.

    2016-10-01

    We have grown crystals of solid parahydrogen using a single closed-cycle cryostat. We have doped the crystals with rubidium atoms at densities on the order of 1017 cm-3 and used optical pumping to polarize the spin state of the implanted atoms. The optical spectrum of the rubidium atoms shows larger broadening than previous work in which the rubidium was implanted in solid argon or neon. However, the optical pumping behavior is significantly improved, with both a larger optical pumping signal and a longer longitudinal relaxation time. The spin relaxation time shows a strong dependence on orthohydrogen impurity levels in the crystal, as well as the applied magnetic field. Current performance is comparable to state-of-the-art solid state systems at comparable spin densities, with potential for improvement at higher parahydrogen purities.

  9. Coherent continuous-wave dual-frequency high-Q external-cavity semiconductor laser for GHz-THz applications.

    PubMed

    Paquet, Romain; Blin, Stéphane; Myara, Mikhaël; Gratiet, Luc Le; Sellahi, Mohamed; Chomet, Baptiste; Beaudoin, Grégoire; Sagnes, Isabelle; Garnache, Arnaud

    2016-08-15

    We report a continuous-wave highly-coherent and tunable dual-frequency laser emitting at two frequencies separated by 30 GHz to 3 THz, based on compact III-V diode-pumped quantum-well surface-emitting semiconductor laser technology. The concept is based on the stable simultaneous operation of two Laguerre-Gauss transverse modes in a single-axis short cavity, using an integrated sub-wavelength-thick metallic mask. Simultaneous operation is demonstrated theoretically and experimentally by recording intensity noises and beat frequency, and time-resolved optical spectra. We demonstrated a >80  mW output power, diffraction-limited beam, narrow linewidth of <300  kHz, linear polarization state (>45  dB), and low intensity noise class-A dynamics of <0.3% rms, thus opening the path to a compact low-cost coherent GHz to THz source development.

  10. Radiation trapping in rubidium optical pumping at low buffer-gas pressures

    SciTech Connect

    Rosenberry, M. A.; Reyes, J. P.; Gay, T. J.; Tupa, D.

    2007-02-15

    We have made a systematic study of rubidium optical pumping in a simple cylindrical cell geometry with a high-power 10 W diode laser array, low magnetic fields, and buffer-gas pressures of less than 50 torr. We have determined rubidium polarizations experimentally for H{sub 2}, N{sub 2}, He, and Ar buffer gases, with Rb number densities from 10{sup 12} to 10{sup 13} cm{sup -3}. Comparison to a relatively simple optical pumping model allows us to extract useful information about radiation trapping and quenching effects.

  11. Optical pumping of metastable NH radicals into the paramagnetic ground state

    SciTech Connect

    Meerakker, Sebastiaan Y.T. van de; Mosk, Allard P.; Jongma, Rienk T.; Sartakov, Boris G.; Meijer, Gerard

    2003-09-01

    We here report on the optical pumping of both {sup 14}NH and {sup 15}NH radicals from the metastable a {sup 1}{delta} state into the X {sup 3}{sigma}{sup -} ground state in a molecular beam experiment. By inducing the hitherto unobserved spin-forbidden A {sup 3}{pi} <- a {sup 1}{delta} transition, followed by spontaneous emission to the X {sup 3}{sigma}{sup -} state, a unidirectional pathway for population transfer from the metastable state into the electronic ground state is obtained. The optical pumping scheme demonstrated here opens up the possibility to accumulate NH radicals in a magnetic or optical trap.

  12. The implementation of high speed digital PSD in optically pumping magnetometers

    NASA Astrophysics Data System (ADS)

    Chen, Jun; Cheng, Defu; Zhou, Zhijian; Ma, Ming; Wang, Chao; Hu, Ruifan

    2017-01-01

    The 4He optically pumping magnetometer is a kind of high resolution instrument for measuring magnetic field intensity. Its response speed cannot meet the requirements in some experiments. By analyzing many factors, Phase Sensitive Detector (PSD) which is the key part of the lock-in amplifier processes data at a very slow speed is found. To improve its performance, this paper introduces a parallel digital phase sensitive detector based on coordinate rotation digital computer (CORDIC) algorithm. The cost time of the parallel digital phase sensitive detector is only 5.1% of the previous one. It can greatly enhance the response speed of the 4He optically pumping magnetometer.

  13. External-Cavity Quantum Cascade Laser Spectroscopy for Mid-IR Transmission Measurements of Proteins in Aqueous Solution.

    PubMed

    Alcaráz, Mirta R; Schwaighofer, Andreas; Kristament, Christian; Ramer, Georg; Brandstetter, Markus; Goicoechea, Héctor; Lendl, Bernhard

    2015-07-07

    In this work, we report mid-IR transmission measurements of the protein amide I band in aqueous solution at large optical paths. A tunable external-cavity quantum cascade laser (EC-QCL) operated in pulsed mode at room temperature allowed one to apply a path length of up to 38 μm, which is four times larger than that applicable with conventional FT-IR spectrometers. To minimize temperature-induced variations caused by background absorption of the ν2-vibration of water (HOH-bending) overlapping with the amide I region, a highly stable temperature control unit with relative temperature stability within 0.005 °C was developed. An advanced data processing protocol was established to overcome fluctuations in the fine structure of the emission curve that are inherent to the employed EC-QCL due to its mechanical instabilities. To allow for wavenumber accuracy, a spectral calibration method has been elaborated to reference the acquired IR spectra to the absolute positions of the water vapor absorption bands. Employing this setup, characteristic spectral features of five well-studied proteins exhibiting different secondary structures could be measured at concentrations as low as 2.5 mg mL(-1). This concentration range could previously only be accessed by IR measurements in D2O. Mathematical evaluation of the spectral overlap and comparison of second derivative spectra confirm excellent agreement of the QCL transmission measurements with protein spectra acquired by FT-IR spectroscopy. This proves the potential of the applied setup to monitor secondary structure changes of proteins in aqueous solution at extended optical path lengths, which allow experiments in flow through configuration.

  14. Short-pulse controlled optical switch using external cavity based single mode Fabry-Pérot laser diode.

    PubMed

    Nakarmi, Bikash; Hoai, Tran Quoc; Won, Yong-Hyub; Zhang, Xuping

    2014-06-30

    We propose and demonstrate a novel scheme for short pulse controlled all-optical switch using external cavity based single mode Fabry- Pérot laser diode (SMFP-LD). The proposed scheme consists of control unit and switching unit as two essential blocks. The basic principle of the proposed scheme is the optical bistability property of SMFP-LD for the control unit and the suppression of the dominant beam of SMFP-LD with injection locking for the switching unit. We also present the analysis of hysteresis width and rising/falling time with change in wavelength detuning which helps to find the optimum wavelength detuning value and power of light beams at different stages of the proposed scheme that gives wide input dynamic power range, high ON/OFF contrast ratio, and low rising/falling time. Input data of 10 Gb/s Non Return to Zero (NRZ) signal is switched at output ports depending upon the control signal generated by the control unit, which comprises of optical SR latch. Output waveforms, clear eye diagrams with extinction ratio of about 11 dB, rising/falling time of about 30 ps and 40 ps, and bit error rate (BER) are measured to validate proposed scheme. No noise floor is observed at output ports up to BER of 10-(12) and the maximum power penalty recorded is about 1.7 dB at a BER of 10-(9) which shows good performance of the proposed short pulse controlled optical switch using SMFP-LDs.

  15. Rapid and sensitive quantification of isotopic mixtures using a rapidly-swept external cavity quantum cascade laser

    SciTech Connect

    Brumfield, Brian E.; Taubman, Matthew S.; Phillips, Mark C.

    2016-05-23

    A rapidly-swept external-cavity quantum cascade laser with an open-path Herriott cell is used to quantify gas-phase chemical mixtures of D2O and HDO at a rate of 40 Hz (25-ms measurement time). The chemical mixtures were generated by evaporating D2O liquid near the open-path Herriott cell, allowing the H/D exchange reaction with ambient H2O to produce HDO. Fluctuations in the ratio of D2O and HDO on timescales of <1 s due to the combined effects of plume transport and the H/D exchange chemical reaction are observed. Noise-equivalent concentrations (1σ) (NEC) of 147.0 ppbv and 151.6 ppbv in a 25-ms measurement time are determined for D2O and HDO, respectively, with a 127-m optical path. These NECs are improved to 23.0 and 24.0 ppbv with a 1-s averaging time for D2O and HDO, respectively. NECs <200 ppbv are also estimated for N2O, 1,1,1,2–tetrafluoroethane (F134A), CH4, acetone and SO2 for a 25-ms measurement time. Finally, the isotopic precision for measurement of the [D2O]/[HDO] concentration ratio of 33‰ and 5‰ is calculated for the current experimental conditions for measurement times of 25 ms and 1 s, respectively.

  16. Widely tunable eye-safe laser by a passively Q-switched photonic crystal fiber laser and an external-cavity optical parametric oscillator

    NASA Astrophysics Data System (ADS)

    Chang, H. L.; Zhuang, W. Z.; Huang, W. C.; Huang, J. Y.; Huang, K. F.; Chen, Y. F.

    2011-09-01

    We report on a widely tunable passively Q-switched photonic crystal fiber (PCF) laser with wavelength tuning range up to 80 nm. The PCF laser utilizes an AlGaInAs quantum well/barrier structure as a saturable absorber and incorporates an external-cavity optical parametric oscillator (OPO) to achieve wavelength conversion. Under a pump power of 13.1 W at 976 nm, the PCF laser generated 1029-nm radiation with maximum output energy of 750 μJ and was incident into an external-cavity OPO. The output energy and peak power of signal wave was found to be 138 μJ and 19 kW, respectively. By tuning the temperature of nonlinear crystal, periodically poled lithium niobate (PPLN), in the OPO, the signal wavelength in eye-safe regime from 1513 to 1593 nm was obtained.

  17. Extending the mode-hop-free tuning range of an external-cavity diode laser by synchronous tuning with mode matching.

    PubMed

    Gong, Hai; Liu, Zhigang; Zhou, Yangli; Zhang, Weibo

    2014-11-20

    We present an effective method to extend the mode-hop-free (MHF) tuning range of an external-cavity diode laser (ECDL) by synchronous tuning of the longitudinal modes of the external cavity and the internal cavity, with the mode also matched in the initial state. Both the principle of synchronous tuning and the condition of mode matching in a Littman-configuration ECDL are introduced. The necessary tuning parameters could simply be estimated by the output power curve of the tuning with a single photodiode. By using this tuning method, we increased the MHF tuning range of an ECDL with a nonoptimized reflector pivot position from several gigahertzes to over 78 GHz around 774.5 nm. The tuning performance of the ECDL could meet the requirement of frequency scanned interferometry.

  18. External cavity diode lasers with 5kHz linewidth and 200nm tuning range at 1.55μm and methods for linewidth measurement.

    PubMed

    Bennetts, Shayne; McDonald, Gordon D; Hardman, Kyle S; Debs, John E; Kuhn, Carlos C N; Close, John D; Robins, Nicholas P

    2014-05-05

    Two simple external cavity diode laser designs using fibre pigtailed gain chips are tested and their properties compared with a high end DBR fibre laser. These ECDLs demonstrate a FWHM linewidth as low as 5.2kHz with a fitted Lorentzian FWHM linewidth as low as 1.6kHz. Tuning ranges of 200nm covering 1420nm to 1620nm were demonstrated. To the best of our knowledge these are the narrowest linewidth and most broadly tunable external cavity diode lasers reported to date. The improvement in linewidth is attributed to greatly enhanced acoustic isolation allowed by using fiber coupled gain chips and by replacing kinematic mounts with a pair of rotatable wedges for cavity alignment which eliminates acoustic resonances. A detailed description and discussion of techniques used to characterize the frequency noise and linewidths of these lasers is provided.

  19. Narrow linewidth single-frequency terahertz source based on difference frequency generation of vertical-external-cavity source-emitting lasers in an external resonance cavity.

    PubMed

    Paul, Justin R; Scheller, Maik; Laurain, Alexandre; Young, Abram; Koch, Stephan W; Moloney, Jerome

    2013-09-15

    We demonstrate a continuous wave, single-frequency terahertz (THz) source emitting 1.9 THz. The linewidth is less than 100 kHz and the generated THz output power exceeds 100 μW. The THz source is based on parametric difference frequency generation within a nonlinear crystal located in an optical enhancement cavity. Two single-frequency vertical-external-cavity source-emitting lasers with emission wavelengths spaced by 6.8 nm are phase locked to the external cavity and provide pump photons for the nonlinear downconversion. It is demonstrated that the THz source can be used as a local oscillator to drive a receiver used in astronomy applications.

  20. Extension of the mode-hop-free tuning range of an external cavity diode laser based on a model of the mode-hop dynamics.

    PubMed

    Führer, Thorsten; Walther, Thomas

    2008-02-15

    We report on a universal method to achieve and sustain a large mode-hop-free tuning range of an external cavity diode laser based on a model of its mode-structure dynamics. Using this method, we were able to scan 73 GHz mode-hop free by using an uncoated off-the-shelf laser diode with a central wavelength of 785 nm. Our model applies to any laser system requiring synchronization of more than one optical element.

  1. CONTROL OF LASER RADIATION PARAMETERS: Instability of stationary lasing and self-starting mode locking in external-cavity semiconductor lasers

    NASA Astrophysics Data System (ADS)

    Smetanin, Igor V.; Vasil'ev, Petr P.

    2009-01-01

    Parameters of external-cavity semiconductor lasers, when the stationary lasing becomes unstable, were analysed within the framework of a theoretical model of self-starting mode locking. In this case, a train of ultrashort pulses can be generated due to intrinsic nonlinearities of the laser medium. A decisive role of the transverse optical field nonuniformity, pump rate, and gain spectral bandwidth in the development of the instability of stationary lasing was demonstrated.

  2. Measurement of laser heating in spin exchange optical pumping by NMR diffusion sensitization gradients

    SciTech Connect

    Parnell, Steven R.; Deppe, Martin H.; Ajraoui, Salma; Parra-Robles, Juan; Wild, Jim M.; Boag, Stephen

    2010-05-15

    This paper details pulsed gradient NMR measurements of the {sup 3}He diffusion coefficient in sealed cells during spin exchange optical pumping. The potential of ultra low field magnetic resonance imgaing (MRI) and NMR for noninvasive measurement of cell pressure is demonstrated. Diffusion sensitization gradients allow measurement of the {sup 3}He diffusion coefficient from which the pressure and/or temperature of the gas can be determined during optical pumping. The pressure measurements were compared with neutron time of flight transmission measurements. Good agreement was observed between the temperature/pressure measurements and predictions based on Chapman-Enskog theory. The technique had sufficient sensitivity to observe the diffusion coefficient increasing with temperature in a sealed cell. With this method, evidence for laser heating of the {sup 3}He during optical pumping was found. The results show that NMR diffusion measurements allow noninvasive measurement of the cell temperature and/or pressure in an optical pumping setup. The method can be expanded using MRI to probe the spatial distribution of the diffusion coefficient. These techniques can be applied to the further investigation of polarization limiting effects such as laser heating.

  3. Progress in High-Field Optical Pumping of Alkali Metal Nuclei

    NASA Astrophysics Data System (ADS)

    Patton, B.; Ishikawa, K.; Jau, Y.-Y.; Happer, W.

    2006-05-01

    We present preliminary results of an attempt to polarize alkali metal nuclei via optical pumping in a large (9.4-tesla) magnetic field. NMR measurements of ^87Rb and ^133Cs films in optical cells will be reported. Depopulation pumping of alkalis can easily produce electron polarizations of order unity, as measured during spin-exchange optical pumping of noble gases [1]. At low magnetic fields (< ˜1 kG), the strong hyperfine coupling between the alkali electron and nucleus allows angular momentum exchange from one to the other, resulting in nuclear polarization enhancement through optical pumping. In the high magnetic fields required for NMR, however, this interaction is largely decoupled and electron-nuclear spin exchange must rely upon the δA I .S interaction induced by buffer gas collisions (also called the ``Carver rate''). High-field optical pumping experiments may allow for a more precise measurement of this rate, as well as yielding insight into the transfer of angular momentum from the polarized alkali vapor to the bulk alkali metal on the cell walls. The technical challenges of high-resolution NMR of alkali metals at 9.4 tesla will be discussed. 1. E. Babcock, I. Nelson, S. Kadlecek, et al., Physical Review Letters 91, 123003 (2003).

  4. A high field optical-pumping spin-exchange polarized deuterium source

    SciTech Connect

    Coulter, K.P.; Holt, R.J.; Kinney, E.R.; Kowalczyk, R.S.; Poelker, M.; Potterveld, D.H.; Young, L.; Zeidman, B. ); Toporkov, D. . Inst. Yadernoj Fiziki)

    1992-01-01

    Recent results from a prototype high field optical-pumping spin-exchange polarized deuterium source are presented. Atomic polarization as high as 62% have been observed with an intensity of 6.3 [times] 10[sup 17] atoms-sec[sup [minus]1] and 65% dissociation fraction.

  5. Towards loss compensated and lasing terahertz metamaterials based on optically pumped graphene

    NASA Astrophysics Data System (ADS)

    Weis, P.; Garcia-Pomar, J. L.; Rahm, M.

    2014-04-01

    It is evidenced by numerical calculations that optically pumped graphene is suitable for compensating inherent loss in terahertz (THz) metamaterials. In a first step, the complex conductivity of graphene under optical pumping is calculated and the proper conditions for terahertz amplification in single layer graphene are determined. It is shown that amplification in graphene occurs for temperatures up to room temperature and for moderate pump intensities when pumped at a telecommunication wavelength $\\lambda=1.5~\\mathrm{\\mu m}$. Furthermore, the amplification properties of graphene are evaluated and discussed at a temperature as low as $T=77~\\mathrm{K}$ and a pump intensity $I=300~\\mathrm{mW/mm^2}$ to investigate the coupling between graphene and a plasmonic split ring resonator (SRR) metamaterial. The contributions of ohmic and dielectric loss mechanisms are studied by full wave simulations. As a result, it is found that the loss of a split-ring resonator metamaterial can be compensated by optically stimulated amplification in graphene. Moreover, it is shown that a hybrid material consisting of asymmetric split-ring resonators and optically pumped graphene can exceed the laser threshold condition and can emit coherent THz radiation at minimum output power levels of $6 0~\\mathrm{nW/mm^2}$. The use of optically pumped graphene is well suited for loss compensation in THz metamaterials and paves the way to new kinds of coherent THz sources.

  6. Energy-transfer mechanisms in the CH3F-SF6 optically pumped laser

    NASA Technical Reports Server (NTRS)

    Lawandy, N. M.; Koepf, G. A.

    1980-01-01

    The power of an optically pumped CH3F laser operating on the 496-micron line has been doubled with the addition of SF6 without any corresponding increase in pump absorption. It is suggested that a near-resonant energy transfer between CH3F and SF6 followed by SF6 deactivation is the mechanism responsible for the enhancement.

  7. Double-resonance study of vibrational equilibration in optically pumped laser molecules

    NASA Technical Reports Server (NTRS)

    Lawandy, N. M.; Koepf, G. A.

    1981-01-01

    A CW frequency-locked CO2 laser is used in conjunction with a 1-J TEA CO2 laser to observe the vibrational equilibration of optically pumped gases. Velocity-dependent effects in the vibrational-deactivation rate are also observed. Experimental results are given for CH3F

  8. External cavity laser using a InAs quantum dot gain chip and an arrayed-waveguide grating for T-band optical communications

    NASA Astrophysics Data System (ADS)

    Shibutani, Hideki; Tomomatsu, Yasunori; Sawado, Yoshinori; Yoshizawa, Katsumi; Asakura, Hideaki; Idris, Nazirul Afham; Tsuda, Hiroyuki

    2015-02-01

    Utilizing T-band (1000 nm to 1260 nm) for optical communications is promising for short reach, and large capacity networks, such as data centers or access networks. It is feasible to use this with low-cost coarse wavelength division multiplexing (WDM). However, a tunable wavelength light source is necessary for such applications. In this paper, we propose a new configuration for an external cavity laser, which uses a silica-based arrayed waveguide grating (AWG) for the wavelength selecting element. The external cavity laser consists of a gain chip with high reflection (HR) and anti-reflection (AR) coated facets, coupling lenses, an AWG with AR/HR coatings, and an output fiber. The AWG has 17 connection ports, which correspond to 17 wavelengths with a channel spacing of 1.67 nm. The width of the connection port waveguides was optimized to achieve high coupling efficiency. The AWG chip size is 15 mm x 30 mm. The active layer in the gain chip has InAs quantum dots. The spontaneous emission 3-dB bandwidth was 48 nm (1108 nm to 1156 nm) when a current of 150 mA was injected into the gain chip. The lasing wavelength of the external cavity laser was successfully tuned from 1129.9 nm to 1154.4 nm by selecting the connection ports of the AWG. The typical threshold current was about 130 mA.

  9. Spatially-selective optical pumping cooling and Two-Isotope Collision-Assisted Zeeman cooling

    NASA Astrophysics Data System (ADS)

    Wilson, Rebekah Ferrier

    In this thesis I describe two non-evaporative cooling schemes for cooling Rb atoms. The first is a Sisyphus-like ultracold gas cooling scheme called Spatially-selecTive Optical Pumping (STOP) cooling. In principle, STOP cooling has wide applicability to both atoms and molecules. STOP cooling works by exploiting the fact that atoms or molecules in a confining potential can be optically pumped out of an otherwise dark state in a spatially-selective way. Selecting atoms or molecules for optical pumping out of a dark state in a region of high potential energy and then waiting a fixed time after the optical pumping allows for the creation of a group of high kinetic energy atoms or molecules moving in a known direction. These can then be slowed using external fields (such as the scattering force from a resonant laser beam) and optically pumped back into the dark state, cooling the gas and closing the cooling cycle. I present theoretical modeling of the STOP cooling technique, including predictions of achievable cooling rates. I have conducted an experimental study of the cooling technique for a single cooling cycle, observing one dimensional cooling rates in excess of 100 micro-K per second in an ultracold gas of 87 Rb atoms. I will also comment on the prospects for improving the cooling performance beyond that presented in this work. The second cooling scheme I investigated is called Two-Isotope Collision Assisted Zeeman (2-CAZ) cooling. Through a combination of spin-exchange collisions in a magnetic field and optical pumping, it is possible to cool a gas of atoms without requiring the loss of atoms from the gas. I investigated 2-CAZ cooling using 85Rb and 87Rb. I was able to experimentally confirm that the measured 2-CAZ cooling rate agreed with a cooling rate predicted though a simple analytic model. As part of the measured cooling rate, I quantitatively characterized the heating rates associated with our actual implementation of this cooling technique and found

  10. THz wave parametric oscillator with a surface-emitted ring-cavity configuration

    NASA Astrophysics Data System (ADS)

    Yang, Zhen; Wang, Yuye; Xu, Degang; Tang, Longhuang; Xu, Wentao; Duan, Pan; Yan, Chao; Yao, Jianquan

    2016-11-01

    A surface-emitted ring-cavity terahertz (THz) wave parametric oscillator has been demonstrated for high-energy THz output and fast frequency tuning. Through the special optical design with a Galvano optical scanner and four-mirror ring-cavity structure, a maximum THz output of 12.9 μJ/pulse is achieved at 1.359 THz under the pump pulse energy of 172.8 mJ with the repetition rate of 10 Hz. A further research on the performance of the SE ring-cavity TPO has done to explore more characteristics of THz output. The THz pulse instability and the influence of cavity loss has analyzed. Moreover, the pump depletion rate of the ring-cavity configuration is much lower than the conventional surface-emitted terahertz wave parametric oscillator at the same experimental conditions.

  11. Phase-locked arrays of vertical-cavity surface-emitting lasers

    SciTech Connect

    Warren, M.E.; Lear, K.L.; Gourley, P.L.; Hadley, G.R.; Vawter, G.A.; Brennan, T.M.; Hammons, B.E.; Zolper, J.C.; Lott, J.A.; Chalmers, S.A.

    1994-04-01

    Vertical-Cavity Surface-Emitting Lasers (VCSELS) are of increasing interest to the photonics community because of their surface-emitting structure, simple fabrication and packaging, wafer-level testability, and potential for low cost manufacture. Scaling VCSELs to higher power outputs requires increasing the device area, which leads to transverse mode control difficulties if devices become larger than about 5 microns. One approach to increasing the device size while maintaining a well controlled transverse mode profile is formation of coupled or phase-locked two-dimensional arrays of VCSELs that are individually single-transverse mode. Such arrays have unique optical properties, not all of which are desirable. This paper covers some of the basic principles of these devices and reviews recent work on device designs, fabrication and operation. A technique for improving the far-field properties of the arrays is demonstrated and performance limitations are discussed.

  12. Dynamic Range of Vertical Cavity Surface Emitting Lasers in Multimode Links

    SciTech Connect

    Lee, H.L.T.; Dalal, R.V.; Ram, R.J.; Choquette, K.D.

    1999-07-07

    The authors report spurious free dynamic range measurements of 850nm vertical cavity surface emitting lasers in short multimode links for radio frequency communication. For a 27m fiber link, the dynamic range at optimal bias was greater than 95dB-Hz{sup 2/3} for modulation frequencies between 1 and 5.5 GHz, which exceeds the requirements for antenna remoting in microcellular networks. In a free space link, they have measured the highest dynamic range in an 850nm vertical cavity surface emitting laser of 113dB-Hz{sup 2/3} at 900MHz. We have also investigated the effects of modal noise and differential mode delay on the dynamic range for longer lengths of fiber.

  13. Vertical cavity surface-emitting semiconductor lasers with injection laser pumping

    NASA Astrophysics Data System (ADS)

    McDaniel, D. L., Jr.; McInerney, J. G.; Raja, M. Y. A.; Schaus, C. F.; Brueck, S. R. J.

    1990-05-01

    Continuous-wave GaAs/GaAlAs edge-emitting diode lasers were used to pump GaAs/AlGaAs and InGaAs/AlGaAs vertical cavity surface-emitting lasers (VCSELs) with resonant periodic gain (RPG) at room temperature. Pump threshold as low as 11 mW, output powers as high as 27 mW at 850 nm, and external differential quantum efficiencies of about 70 percent were observed in GaAs/AlGaAs surface -emitters; spectral brightness 22 times that of the pump laser was also observed. Output powers as high as 85 mW at 950 nm and differential quantum efficiencies of up to 58 percent were recorded for the InGaAs surface-emitting laser. This is the highest quasi-CW output power ever reported for any RPG VCSEL, and the first time such a device has been pumped using an injection laser diode.

  14. Spectral locking in an extended area two-dimensional coherent grating surface emitting laser array

    SciTech Connect

    DeFreez, R.K.; Ximen, H.; Bossert, D.J.; Hunt, J.M.; Wilson, G.A.; Elliott, R.A.; Orloff, J. ); Evans, G.A.; Carlson, N.W.; Lurie, M. )

    1990-01-01

    The spectral properties of a monolithic pair of two-dimensional coherent grating surface emitting laser arrays optically coupled by means of total-internal-reflection (TIR) corner turning mirrors have been studied. Each of the pair consists of six groups of ten laterally {ital Y}-coupled, index-guided ridge lasers interspersed with second-order DBR grating sections in the longitudinal direction to provide feedback and surface emitting output coupling. The turning mirrors were formed by focused-ion-beam micromachining channels in the wafer angled at 45{degrees} to the laser waveguide. Locking of the emission spectra of the pair of GSE arrays and shifting of the spectrum of one of the pair by varying the drive current to one gain section in the other is demonstrated.

  15. Monolithic integration of vertical-cavity surface-emitting lasers with in-plane waveguides

    NASA Astrophysics Data System (ADS)

    Witzens, Jeremy; Scherer, Axel; Pickrell, Gregory; Louderback, Duane; Guilfoyle, Peter

    2005-03-01

    The ability to couple light from a vertical-cavity surface-emitting laser into a planar, on-chip waveguide creates new opportunities for achieving higher levels of integration and functionality. Here we propose to use a strong grating etched into a waveguide defined into the top layer of the epitaxially grown structure, so that epitaxial regrowth is not required. By introducing a defect mode into the cavity we were able to achieve a 40% coupling efficiency even though light is coupled through a ninety degrees bend. We also show that polarization control of the vertical-cavity surface-emitting laser is enhanced by coupling to the defect mode. Calculations were performed using the finite-difference time-domain method.

  16. High-energy terahertz wave parametric oscillator with a surface-emitted ring-cavity configuration.

    PubMed

    Yang, Zhen; Wang, Yuye; Xu, Degang; Xu, Wentao; Duan, Pan; Yan, Chao; Tang, Longhuang; Yao, Jianquan

    2016-05-15

    A surface-emitted ring-cavity terahertz (THz) wave parametric oscillator has been demonstrated for high-energy THz output and fast frequency tuning in a wide frequency range. Through the special optical design with a galvano-optical scanner and four-mirror ring-cavity structure, the maximum THz wave output energy of 12.9 μJ/pulse is achieved at 1.359 THz under the pump energy of 172.8 mJ. The fast THz frequency tuning in the range of 0.7-2.8 THz can be accessed with the step response of 600 μs. Moreover, the maximum THz wave output energy from this configuration is 3.29 times as large as that obtained from the conventional surface-emitted THz wave parametric oscillator with the same experimental conditions.

  17. Means for phase locking the outputs of a surface emitting laser diode array

    NASA Technical Reports Server (NTRS)

    Lesh, James R. (Inventor)

    1987-01-01

    An array of diode lasers, either a two-dimensional array of surface emitting lasers, or a linear array of stripe lasers, is phase locked by a diode laser through a hologram which focuses the output of the diode laser into a set of distinct, spatially separated beams, each one focused onto the back facet of a separate diode laser of the array. The outputs of the diode lasers thus form an emitted coherent beam out of the front of the array.

  18. Spatial distribution of the intensity noise of a vertical-cavity surface-emitting semiconductor laser.

    PubMed

    Bramati, A; Hermier, J P; Khoury, A Z; Giacobino, E; Schnitzer, P; Michalzik, R; Ebeling, K J; Poizat, J P; Grangier, P

    1999-07-01

    We studied anticorrelated quantum fluctuations between the TEM(00) and the TEM(01) transverse modes of a vertical-cavity surface-emitting semiconductor laser by measuring the transverse spatial distribution of the laser beam intensity noise. Our experimental results are found to be in good agreement with the predictions of a phenomenological model that accounts for quantum correlations between transverse modes in a light beam.

  19. Monolithic excitation and manipulation of surface plasmon polaritons on a vertical cavity surface emitting laser

    NASA Astrophysics Data System (ADS)

    Lamy, J.-M.; Justice, J.; Lévêque, G.; Corbett, B.

    2011-06-01

    We report the manipulation of surface plasmon polaritons (SPPs) on a thin Au layer integrated on top of the mirror of a vertical-cavity surface-emitting laser (VCSEL). Gratings etched into the Au layer to different depths are used to couple the light into and out of the film, and to bend the trajectory of the SPP. The result paves the way to compact integrated plasmonic devices.

  20. Two-frequency injection on a multimode vertical-cavity surface-emitting laser.

    PubMed

    Lin, Hong; Pierce, David W; Basnet, Amod J; Quirce, Ana; Zhang, Yu; Valle, Angel

    2011-11-07

    We have studied experimentally effects of two-frequency optical injection on a multimode vertical-cavity surface-emitting laser (VCSEL). The injected signal comes from another VCSEL. Polarization switching (PS) with and without frequency locking occurs for relatively small frequency detuning. Outside the regime of polarization switching, the VCSEL demonstrates two types of instabilities. The instability regions and boundaries of PS of each transverse mode are mapped in the parameter plane of frequency detuning versus injected power.