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Sample records for sulfide laser crystals

  1. Transition-metal doped sulfide, selenide, and telluride laser crystal and lasers

    DOEpatents

    Krupke, W.F.; Page, R.H.; DeLoach, L.D.; Payne, S.A.

    1996-07-30

    A new class of solid state laser crystals and lasers are formed of transition metal doped sulfide, selenide, and telluride host crystals which have four fold coordinated substitutional sites. The host crystals include II-VI compounds. The host crystal is doped with a transition metal laser ion, e.g., chromium, cobalt or iron. In particular, Cr{sup 2+}-doped ZnS and ZnSe generate laser action near 2.3 {micro}m. Oxide, chloride, fluoride, bromide and iodide crystals with similar structures can also be used. Important aspects of these laser materials are the tetrahedral site symmetry of the host crystal, low excited state absorption losses and high luminescence efficiency, and the d{sup 4} and d{sup 6} electronic configurations of the transition metal ions. The same materials are also useful as saturable absorbers for passive Q-switching applications. The laser materials can be used as gain media in amplifiers and oscillators; these gain media can be incorporated into waveguides and semiconductor lasers. 18 figs.

  2. Transition-metal doped sulfide, selenide, and telluride laser crystal and lasers

    DOEpatents

    Krupke, William F.; Page, Ralph H.; DeLoach, Laura D.; Payne, Stephen A.

    1996-01-01

    A new class of solid state laser crystals and lasers are formed of transition metal doped sulfide, selenide, and telluride host crystals which have four fold coordinated substitutional sites. The host crystals include II-VI compounds. The host crystal is doped with a transition metal laser ion, e.g., chromium, cobalt or iron. In particular, Cr.sup.2+ -doped ZnS and ZnSe generate laser action near 2.3 .mu.m. Oxide, chloride, fluoride, bromide and iodide crystals with similar structures can also be used. Important aspects of these laser materials are the tetrahedral site symmetry of the host crystal, low excited state absorption losses and high luminescence efficiency, and the d.sup.4 and d.sup.6 electronic configurations of the transition metal ions. The same materials are also useful as saturable absorbers for passive Q-switching applications. The laser materials can be used as gain media in amplifiers and oscillators; these gain media can be incorporated into waveguides and semiconductor lasers.

  3. Laser demonstrations of rare-earth ions in low-phonon chloride and sulfide crystals

    SciTech Connect

    Nostrand, M; Page, R; Payne, S; Schunemann, P; Isaenko, L

    2000-04-01

    Laser results are summarized for the low-phonon hosts KPb{sub 2}Cl{sub 5} and CaGa{sub 2}S{sub 4}. Radiative quantum efficiencies were determined in KPb{sub 2}Cl{sub 5}:Dy{sup 3+} directly from emission spectra in order to accurately determine its long-wavelength potential. The results indicate that room-temperature laser action should be possible to near 9 {micro}m in this host.

  4. Laser Crystal

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Lightning Optical Corporation, under an SBIR (Small Business Innovative Research) agreement with Langley Research Center, manufactures oxide and fluoride laser gain crystals, as well as various nonlinear materials. The ultimate result of this research program is the commercial availability in the marketplace of a reliable source of high-quality, damage resistant laser material, primarily for diode-pumping applications.

  5. Photonic Crystal Microchip Laser

    PubMed Central

    Gailevicius, Darius; Koliadenko, Volodymyr; Purlys, Vytautas; Peckus, Martynas; Taranenko, Victor; Staliunas, Kestutis

    2016-01-01

    The microchip lasers, being very compact and efficient sources of coherent light, suffer from one serious drawback: low spatial quality of the beam strongly reducing the brightness of emitted radiation. Attempts to improve the beam quality, such as pump-beam guiding, external feedback, either strongly reduce the emission power, or drastically increase the size and complexity of the lasers. Here it is proposed that specially designed photonic crystal in the cavity of a microchip laser, can significantly improve the beam quality. Experiments show that a microchip laser, due to spatial filtering functionality of intracavity photonic crystal, improves the beam quality factor M2 reducing it by a factor of 2, and increase the brightness of radiation by a factor of 3. This comprises a new kind of laser, the “photonic crystal microchip laser”, a very compact and efficient light source emitting high spatial quality high brightness radiation. PMID:27683066

  6. Photonic Crystal Microchip Laser

    NASA Astrophysics Data System (ADS)

    Gailevicius, Darius; Koliadenko, Volodymyr; Purlys, Vytautas; Peckus, Martynas; Taranenko, Victor; Staliunas, Kestutis

    2016-09-01

    The microchip lasers, being very compact and efficient sources of coherent light, suffer from one serious drawback: low spatial quality of the beam strongly reducing the brightness of emitted radiation. Attempts to improve the beam quality, such as pump-beam guiding, external feedback, either strongly reduce the emission power, or drastically increase the size and complexity of the lasers. Here it is proposed that specially designed photonic crystal in the cavity of a microchip laser, can significantly improve the beam quality. Experiments show that a microchip laser, due to spatial filtering functionality of intracavity photonic crystal, improves the beam quality factor M2 reducing it by a factor of 2, and increase the brightness of radiation by a factor of 3. This comprises a new kind of laser, the “photonic crystal microchip laser”, a very compact and efficient light source emitting high spatial quality high brightness radiation.

  7. Physical properties of superconducting single crystal iron sulfide

    NASA Astrophysics Data System (ADS)

    Rodriguez, Efrain E.; Borg, Christopher K. H.; Zhou, Xiuquan; Paglione, Johnpierre; University of Maryland Collaboration

    Recently, the simple binary tetragonal iron sulfide, FeS, was found to be a superconductor with a Tc = 5 K. We have prepared single crystals of tetragonal iron sulfide through hydrothermal de-intercalation of KxFe2-yS2. The KxFe2-yS2 single crystal precursors were grown by slow cooling of stoichiometric melts of K, Fe and S. The silver, plate-like FeS single crystals were highly crystalline with a superconducting transition temperature (Tc) of 4 K. The high quality of the FeS crystals revealed highly anisotropic nature of the magnetic and electronic properties intrinsic to FeS. The physical properties and thermal stability of single crystal FeS will be discussed in detail.

  8. Laser-induced crystallization and crystal growth.

    PubMed

    Sugiyama, Teruki; Masuhara, Hiroshi

    2011-11-01

    Recent streams of laser studies on crystallization and crystal growth are summarized and reviewed. Femtosecond multiphoton excitation of solutions leads to their ablation at the focal point, inducing local bubble formation, shockwave propagation, and convection flow. This phenomenon, called "laser micro tsunami" makes it possible to trigger crystallization of molecules and proteins from their supersaturated solutions. Femtosecond laser ablation of a urea crystal in solution triggers the additional growth of a single daughter crystal. Intense continuous wave (CW) near infrared laser irradiation at the air/solution interface of heavy-water amino acid solutions results in trapping of the clusters and evolves to crystallization. A single crystal is always prepared in a spatially and temporally controlled manner, and the crystal polymorph of glycine depends on laser power, polarization, and solution concentration. Upon irradiation at the glass/solution interface, a millimeter-sized droplet is formed, and a single crystal is formed by shifting the irradiation position to the surface. Directional and selective crystal growth is also possible with laser trapping. Finally, characteristics of laser-induced crystallization and crystal growth are summarized.

  9. Crystal growth of sulfide materials from alkali polysulfide liquids

    NASA Technical Reports Server (NTRS)

    White, W. B.

    1979-01-01

    The fluids experiment system was designed for low temperature solution growth, nominally aqueous solution growth. The alkali polysulfides, compositions in the systems Na2S-S and K2S-S form liquids in the temperature range of 190 C to 400 C. These can be used as solvents for other important classes of materials such as transition metal and other sulfides which are not soluble in aqueous media. Among these materials are luminescent and electroluminescent crystals whose physical properties are sensitive functions of crystal perfection and which could, therefore, serve as test materials for perfection improvement under microgravity conditions.

  10. Photonic crystal microcavity lasers and laser arrays

    NASA Astrophysics Data System (ADS)

    Cao, Jiang-Rong

    As a state-of-the-art technology, photonic crystal microcavity lasers have great potentials to resolve many semiconductor laser performance challenges, owing to their compact size, high spontaneous emission factor, and inherent advantages in dimension scalability. This thesis describes efficient numerical analyzing methods for multimode photonic crystal microcavities, including a parallel computing three-dimensional finite-difference time-domain method combined with Pade interpolation, point group projection, and vectorial Green's function method. With the help of these analyzing tools, various experimental photonic crystal microcavity devices fabricated in InGaAsP/InP based materials were studies. Room temperature optical pumped InGaAsP suspended membrane photonic crystal microcavity lasers were demonstrated. Their lithographical fine-tuning, above room temperature operations, mode identifications and polarizations were demonstrated. Room temperature continuous wave (CW) optically pumped photonic crystal microcavity lasers at diameter less than 3.2 mum were demonstrated with crystalline alpha-Al 2O3 (sapphire) as a cladding layer to the InGaAsP membrane. The far-field radiation profiles from these microcavity lasers were measured and compared with our numerical modeling predictions. Two electrical injection scenes for photonic crystal microcavity lasers were introduced, together with some preliminary results including the demonstrations of optically pumped lasing of highly doped cavities and cavities with an electrical conduction post underneath. Electrically excited photonic crystal microcavity light emitting diodes (LEDs) were also experimentally demonstrated.

  11. Multicolor photonic crystal laser array

    SciTech Connect

    Wright, Jeremy B; Brener, Igal; Subramania, Ganapathi S; Wang, George T; Li, Qiming

    2015-04-28

    A multicolor photonic crystal laser array comprises pixels of monolithically grown gain sections each with a different emission center wavelength. As an example, two-dimensional surface-emitting photonic crystal lasers comprising broad gain-bandwidth III-nitride multiple quantum well axial heterostructures were fabricated using a novel top-down nanowire fabrication method. Single-mode lasing was obtained in the blue-violet spectral region with 60 nm of tuning (or 16% of the nominal center wavelength) that was determined purely by the photonic crystal geometry. This approach can be extended to cover the entire visible spectrum.

  12. Laser schlieren crystal monitor

    NASA Technical Reports Server (NTRS)

    Owen, Robert B. (Inventor); Johnston, Mary H. (Inventor)

    1987-01-01

    A system and method for monitoring the state of a crystal which is suspended in a solution is described which includes providing a light source for emitting a beam of light along an optical axis. A collimating lens is arranged along the optical axis for collimating the emitted beam to provide a first collimated light beam consisting of parallel light rays. By passing the first collimated light beam through a transparent container, a number of the parallel light rays are deflected off the surfaces of said crystal being monitored according to the refractive index gradient to provide a deflected beam of deflected light rays. A focusing lens is arranged along optical axis for focusing the deflected rays towards a desired focal point. A knife edge is arranged in a predetermined orientation at the focal point; and a screen is provided. A portion of the deflected beam is blocked with the knife edge to project only a portion of the deflected beam. A band is created at one edge of the image of the crystal which indicates the state of change of the surface of the crystal being monitored.

  13. Crystal structure controlled synthesis and characterization of copper sulfide nanoparticles

    NASA Astrophysics Data System (ADS)

    Senthilkumar, M.; Babu, S. Moorthy

    2016-05-01

    Phase pure, controlled crystal structure of digenite (Cu9S5) copper sulfide nanoparticles were synthesized by hot injection method at the temperature of 180°C. The mixture of Oleylamine, 1-Octadecene and 1-Dodecanethiol were taken as solvent as well as capping agents. The effect of the mixture of solvents on the phase formation and morphology of the synthesized nanoparticles were analysed. The nanocrystals were characterized using X-Ray diffraction (XRD) which confirms the presence of single phase rhombohedral digenite Cu9S5 NPs, Morphological analysis clearly depicts the formation of hexagonal faceted Cu9S5 NPs, Energy dispersive X-ray absorption spectroscopy (EDS) reveals the stoichiometric ratio of 1.8:1 for synthesized NPs. From the UV-Vis absorption spectroscopy the bandgap value of Cu1.8S is found to be 1.71 eV. The presence of capping agents along the surface of the Cu9S5 NPs was confirmed from FTIR analysis.

  14. Optical and morphological characteristics of zinc selenide-zinc sulfide solid solution crystals

    NASA Astrophysics Data System (ADS)

    Singh, N. B.; Su, Ching-Hua; Arnold, Bradley; Choa, Fow-Sen

    2016-10-01

    Experiments were performed to study the effect of point defects on the optical and morphological characteristics of zinc selenide-zinc sulfide ZnSe-ZnS (ZnSexS(1-x)) solid solution crystals grown under terrestrial (1-g) condition. We used the composition ZnSe0.91S0.09 and ZnSe0.73S0.27 for the detailed studies. Crystals of 8 mm and 12 mm diameter were grown using physical vapor transport methods. These crystals did not exhibit gross defects such as voids, bubbles or precipitates. The photoluminescence spectra indicated strong red emission for the 610-630-nm wavelength region in both crystals. This emission could be explained on the basis of high energy irradiation of Zn selenide. For the ZnSe0.73S0.27 crystal, absorption starts at a lower wavelength range (300 nm) when compared to the ZnSe0.91S0.09 crystal presumably due to the much higher bandgap of ZnS than that of ZnSe. Sharp peaks at 451 and 455 nm were observed for both samples corresponding to the band edge transitions, followed by a strong peak at 632 nm. These results were consistent with the observations based on Raman spectroscopy studies. Under 532-nm laser illumination both transverse optical (TO) and longitudinal optical (LO) phonon peaks appeared at Raman shifts of 220 and 280 Δcm-1, respectively. These peaks are similar to those observed for pure ZnSe Raman spectra for which TO and LO occur at 200 and 250 Δcm-1 for the x-axis (first order) polarization.

  15. Chirped laser dispersion spectroscopy for laser-based hydrogen sulfide detection in open-path conditions.

    PubMed

    Nikodem, Michał

    2016-05-16

    In this paper the design and characterization of a near-IR Chirped Laser Dispersion Spectroscopy (CLaDS)-based setup for hydrogen sulfide (H2S) detection is reported. This system can be implemented for open-path sensing also in standoff configuration. Target transition selection, system noise and detection limit are discussed and characterized. Furthermore, the cross-interference with other molecules is analyzed. CLaDS-based detection is shown to be highly immune to background carbon dioxide changes, which is a critical issue in accurate open-path sensing of hydrogen sulfide.

  16. Stress Tuning of Laser Crystals

    NASA Technical Reports Server (NTRS)

    Carty, Atherton A.

    1995-01-01

    The topic of stress tunable laser crystals is addressed in this study with the purpose of determining the piezo-optic coefficients of a new laser material. This data was collected using a quadruple pass birefringence technique because of its high degree of sensitivity relative to the other methods examined including fringe shift analysis using a Mach-Zender interferometer. A green He-Ne laser was passed through a light chopper and Glan-Thompson prism before entering a crystal of Erbium doped Yttrium Aluminum Garnet (Er:YAG) (used in order to validate the experimental technique). The Er:YAG crystal is mounted in a press mechanism and the laser is quadruple passed through test specimen before being returned through the prism and the orthogonally polarized portion of the beam measured with a optical sensor. At a later stage, the Er:YAG crystal was replaced with a new crystal in order to determine the piezo-optic coefficients of this uncharacterized material. The applied load was monitored with the use of a 50 lb. load cell placed in line with the press. Light transmission readings were taken using a lock-in amplifier while load cell measurements were taken with a voltmeter from a 5 volt, 0.5 amp power supply. Despite the fact that an effective crystal press damping system was developed, size limitations precluded the use of the complete system. For this reason, data points were taken only once per full turn so as to minimize the effect of non uniform load application on the collected data. Good correlation was found in the transmission data between the experimentally determined Er:YAG and the previously known peizo-optic constants of non-doped crystal with which it was compared. The variation which was found between the two could be accounted for by the aforementioned presence of Erbium in the experimental sample (for which exact empirical data was not known). The same test procedure was then carried out on a Yttrium Gallium Aluminum garnet (YGAG) for the purpose of

  17. Laser alexandrite crystals grown by horizontal oriented crystallization technique

    NASA Astrophysics Data System (ADS)

    Gurov, V. V.; Tsvetkov, E. G.; Yurkin, A. M.

    2008-05-01

    Comparative studies were performed for alexandrite crystals, Al 2BeO 4:Cr 3+, employed in solid state lasers and grown by the horizontal oriented crystallization (HOC) technique and alexandrite crystals grown by the Czochralski (Cz) method. It was shown that the structural quality and possibilities of generation of stimulated emission HOC-crystals are similar to Cz-crystals, whereas their damage threshold is about three times higher. The obtained results and considerably lower cost price of HOC-alexandrite crystals prove their advantageous application in powerful laser systems, which require large laser rods with a higher resistance to laser beam. It is emphasized that application of HOC technique is promising for growth of laser crystals of other high-temperature oxide compounds.

  18. Antineoplastic activities of protein-conjugated silver sulfide nano-crystals with different shapes.

    PubMed

    Wang, Hua-Jie; Yang, Lin; Yang, Hua-Yan; Wang, Kui; Yao, Wen-Guang; Jiang, Kai; Huang, Xiao-Lan; Zheng, Zhi

    2010-01-01

    In this paper, antineoplastic activities of protein-conjugated silver sulfide nano-crystals with different shapes were described in detail. Transmission electron microscope analysis demonstrated that stable and well-disperse protein-conjugated silver sulfide nano-particles, nano-rods, and nano-wires could be prepared by aqueous chemistry method. The Fourier transform infrared spectrograph analysis indicated the strong coordination between silver sulfide surfaces and -OH and -NH groups in bovine serum albumin. The antineoplastic activities of protein-conjugated silver sulfide nano-crystals were examined by cell viability analysis, optical and electron microscopy methods. The results showed that nano-particles, nano-rods and nano-wires could inhibit the proliferations of human hepatocellular carcinoma Bel-7402 cells and C6 glioma cells, and the activities were size-dependent.

  19. Quantum Cascade Photonic Crystal lasers

    NASA Astrophysics Data System (ADS)

    Capasso, Federico

    2004-03-01

    QC lasers have emerged in recent years as the dominant laser technology for the mid-to far infrared spectrum in light of their room temperature operation, their tunability, ultrahigh speed operation and broad range of applications to chemical sensing, spectroscopy etc. (Ref. 1-3). After briefly reviewing the latter, I will describe a new class of mid-infrared QC lasers, Quantum Cascade Photonic Crystal Surface Emitting Lasers (QCPCSELS), that combine electronic and photonic band structure engineering to achieve vertical emission from the surface (Ref. 4). Devices operating on bandedge mode and on defect modes will be discussed. Exciting potential uses of these new devices exist in nonlinear optics, microfluidics as well as novel sensors. Finally a bird's eye view of other exciting areas of QC laser research will be given including broadband QCLs and new nonlinear optical sources based on multiwavelength QCLs. 1. F. Capasso, C. Gmachl, D. L. Sivco, and A. Y. Cho, Physics Today 55, 34 (May 2002) 2. F. Capasso, C. Gmachl, R. Paiella, A. Tredicucci, A. L. Hutchinson, D. L. Sivco, J. N. Baillargeon, A. Y. Cho and H. C. Liu, IEEE Journal of Selected Topics in Quantum Electronics, 6, 931 (2000). 3. F. Capasso, R. Paiella, R. Martini, R. Colombelli, C. Gmachl, T. L. Myers, M. S. Taubman, R. M. Williams, C. G. Bethea, K. Unterrainer, H. Y. Hwang, D. L. Sivco, A. Y. Cho, A. M. Sergent, H. C. Liu, E. A. Whittaker, IEEE J. Quantum Electron. 38, 511 (2002) 4. R. Colombelli, K. Srivasan, M. Troccoli, O. Painter, C. Gmachl, D. M. Tennant, A. M. Sergent, D. L. Sivco, A. Y. Cho and F. Capasso, Science 302, 1374 (2003)

  20. Ytterbium-doped borate fluoride laser crystals and lasers

    DOEpatents

    Schaffers, K.I.; DeLoach, L.D.; Payne, S.A.; Keszler, D.A.

    1997-10-14

    A new class of solid state laser crystals and lasers are formed from Yb-doped borate fluoride host crystals. The general formula for the host crystals is MM{prime}(BO{sub 3})F, where M, M{prime} are monovalent, divalent aria trivalent metal cations. A particular embodiment of the invention is Yb-doped BaCaBO{sub 3}F (Yb:BCBF). BCBF and some of the related derivative crystals are capable of nonlinear frequency conversion, whereby the fundamental of the laser is converted to a longer or shorter wavelength. In this way, these new crystals can simultaneously serve as self-frequency doubling crystals and laser materials within the laser resonator. 6 figs.

  1. Ytterbium-doped borate fluoride laser crystals and lasers

    DOEpatents

    Schaffers, Kathleen I.; DeLoach, Laura D.; Payne, Stephen A.; Keszler, Douglas A.

    1997-01-01

    A new class of solid state laser crystals and lasers are formed from Yb-doped borate fluoride host crystals. The general formula for the host crystals is MM'(BO.sub.3)F, where M, M' are monovalent, divalent aria trivalent metal cations. A particular embodiment of the invention is Yb-doped BaCaBO.sub.3 F (Yb:BCBF). BCBF and some of the related derivative crystals are capable of nonlinear frequency conversion, whereby the fundamental of the laser is converted to a longer or shorter wavelength. In this way, these new crystals can simultaneously serve as self-frequency doubling crystals and laser materials within the laser resonator.

  2. Crystal fibers for high power lasers

    NASA Astrophysics Data System (ADS)

    Kim, W.; Florea, C.; Gibson, D.; Peele, J.; Askins, C.; Shaw, B.; Bowman, S.; O'Connor, S.; Bayya, S.; Aggarwal, I.; Sanghera, J. S.

    2013-02-01

    In this paper, we present our recent progress in developing single crystal fibers for high power single frequency fiber lasers. The optical, spectral and morphological properties as well as the loss and gain measured from these crystal fibers drawn by Laser Heated Pedestal Growth (LHPG) system are also discussed. Results on application of various cladding materials on the crystal core and the methods of fiber end-face polishing are also presented.

  3. Liquid crystals for laser applications

    NASA Astrophysics Data System (ADS)

    Jacobs, S. D.; Marshall, K. L.; Schmid, A.

    1992-10-01

    This article highlights some of the advances made in the use of liquid crystals for laser applications from 1982 through 1992. New materials and new effects were discovered, many new devices were developed, and novel applications for well-understood phenomena were conceived. This was quite an eventful time period. Several new books were published on the broad subject of LC's, and the international scientific community organized a society devoted to encouraging further scientific and educational advancement in the field. Attention was focused on LC's in October of 1991 when the Nobel Prize in Physics was awarded to Pierre-Gilles de Gennes for his pioneering work toward understanding order phenomena in LC's and polymers. This article is divided into four sections. The first section discusses new materials, specifically ferroelectric LC's and LC polymers. The former have opened up the realm of submicrosecond response for LC devices, and the latter have significantly reduced the sensitivity of LC optics to temperature. Some new insights into the optical properties of materials are also mentioned. The second section reviews new developments in passive applications for cholesterics and nematics. Included here are the fabrication of cholesteric laser mirrors and apodizers, the use of LC polymers for notch filters and as optical storage media, and some novel nematic retarder concepts such as the distributed polarization rotator.

  4. Artificial silver sulfide Ag2S: Crystal structure and particle size in deposited powders

    NASA Astrophysics Data System (ADS)

    Sadovnikov, S. I.; Gusev, A. I.; Rempel, A. A.

    2015-07-01

    Chemical deposition from aqueous solutions of silver nitrate and sodium sulfide was used for synthesis of coarse-crystalline and nanocrystalline silver sulfide Ag2S powders. Sodium citrate was used as a complexing and stabilizing agent during synthesis. X-ray diffraction study shows that synthesized Ag2S powders have monoclinic (space group P21/c) α-Ag2S acanthite type crystal structure. The unit cell of artificial monoclinic silver sulfide Ag2S contains four Ag2S formula units and has the following parameters: a = 0.42264 nm, b = 0.69282 nm, c = 0.95317 nm and β = 125.554°. The size of silver sulfide particles in deposited powders was estimated by the X-ray diffraction and BET methods. By varying the ratio between the concentrations of reagents in the initial reaction mixture it is possible to deposit Ag2S nanoparticles with average size ranging in the interval from ∼1000 to ∼30 nm. Ag2S nanopowders have no deformation distortions of the crystal lattice practically because the microstrains ε in the synthesized powders do not exceed 0.15%. All the Ag2S powders with different particle size have an identical morphology.

  5. Nanoimprinted polymer photonic crystal dye lasers

    NASA Astrophysics Data System (ADS)

    Christiansen, Mads B.; Smith, Cameron L. C.; Buss, Thomas; Xiao, Sanshui; Mortensen, Niels A.; Kristensen, Anders

    2010-05-01

    Optically pumped polymer photonic crystal band-edge dye lasers are presented. The photonic crystal is a rectangular lattice providing laser feedback as well as an optical resonance for the pump light. The lasers are defined in a thin film of photodefinable Ormocore hybrid polymer, doped with the laser dye Pyrromethene 597. A compact frequency doubled Nd:YAG laser (352 nm, 5 ns pulses) is used to pump the lasers from above the chip. The laser devices are 450 nm thick slab waveguides with a rectangular lattice of 100 nm deep air holes imprinted into the surface. The 2-dimensional rectangular lattice is described by two orthogonal unit vectors of length a and b, defining the ΓP and ΓX directions. The frequency of the laser can be tuned via the lattice constant a (187 nm - 215 nm) while pump light is resonantly coupled into the laser from an angle (θ) depending on the lattice constant b (355 nm). The lasers are fabricated in parallel on a 10 cm diameter wafer by combined nanoimprint and photolithography (CNP). CNP relies on a UV transparent quartz nanoimprint stamp with an integrated metal shadow mask. In the CNP process the photonic crystal is formed by mechanical deformation (imprinting) while the larger features are defined by UV exposure through the combined mask/mold.

  6. Lasing dynamics of photonic crystal reflector laser

    NASA Astrophysics Data System (ADS)

    Bakoz, Andrei P.; Liles, A. A.; Viktorov, E. A.; O'Faolain, L.; Habruseva, T.; Huyet, G.; Hegarty, S. P.

    2016-04-01

    We describe the lasing characteristics of a compact tunable laser source formed by the butt-coupling of a reflective indium phosphide optical amplifier to an SU8 waveguide coupled to few-mode photonic crystal reflector. The short cavity length ensured that only a single longitudinal mode of the device could overlap with each photonic crystal reflection peak.

  7. 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.

  8. Experiment on laser performance of Alexandrite crystals

    SciTech Connect

    ZHANG Shoudu; ZHANG Kemin

    1984-07-01

    The electron vibration laser output in Alexandrite crystals has been obtained. The free oscillation threshold is 170 J, the laser output energy is 140 mJ, and the center wavelength is 7526 A. The emission is linearly polarized in the crystallographic b direction and the laser performance improves at elevated temperatures. Using a quartz double-refraction filter as a tuning element, tunable emission has been observed at room temperature.

  9. Fluoride laser crystals: old and new

    NASA Astrophysics Data System (ADS)

    Jenssen, Hans P.; Cassanho, Arlete

    2006-02-01

    The development of oxide and fluoride materials as gain materials of choice for solid state lasers ranges from early materials such as Calcium Fluoride and Calcium Tungstate crystals to the now ubiquitous Nd hosts YLF, YAG and Vanadate. Among Tunable laser materials, MgF II - an early favorite, gave way to superior oxides such as Alexandrite and Ti:Sapphire only to be followed by development of still newer tunable fluoride media, notably, fluoride colquiriites such as Cr-doped LiSAF and LiCaF. Newer fluoride crystals, such as Barium Yttrium Fluoride BaY II F 8 (BYF), KY 3F 10 (KYF) and the tunable Cr doped LiCaGaF 6 are attractive laser materials, but their growth has not been optimized. Key advantages of two of these new crystals are discussed. Crystal growth results for BYF and Cr:LiCaGaF 6 as well as some material characterization are presented.

  10. Controlling laser emission by selecting crystal orientation

    NASA Astrophysics Data System (ADS)

    Chen, Lijuan; Han, Shujuan; Wang, Zhengping; Wang, Jiyang; Zhang, Huanjin; Yu, Haohai; Han, Shuo; Xu, Xinguang

    2013-01-01

    Based on the anisotropy of laser crystal, we demonstrate a method of adjusting laser emission by selecting crystal orientation. When the light propagating direction varies from a to c axis of Nd:LiGd(MoO4)2 crystal, emission wavelength exhibits a sensitive change of 1061 nm → 1061/1062 + 1068 nm → 1068 nm. The experimental discipline is well explained by a theoretical study of simulating on the spatial distribution of stimulated emission cross-section. This letter manifests that the laser property along non-principal-axis direction is also valuable for research and application, which breaks through the traditional custom of using laser materials processed along principal-axis.

  11. Assessment of Hydrogen Sulfide Minimum Detection Limits of an Open Path Tunable Diode Laser

    EPA Science Inventory

    During June 2007, U.S. EPA conducted a feasibility study to determine whether the EPA OTM 10 measurement approach, also known as radial plume mapping (RPM), was feasible. A Boreal open-path tunable diode laser (OP-TDL) to collect path-integrated hydrogen sulfide measurements alon...

  12. Novel inclusion in laser crystals

    SciTech Connect

    Ma Xiaoshan; Wang Siting; Jin Zhongru; Shen Yafang; Chen Jiaguang

    1986-12-01

    In growing alexandrite crystals, a novel inclusion has been found. The inclusions are quantitatively analyzed by an electronic probe and the mechanism for forming inclusions is suggested. In our Bridgman MgF/sub 2/ crystals, the inclusions in <001> direction have also been observed.

  13. Eurolaser. High power excimer laser: Optical crystals

    NASA Astrophysics Data System (ADS)

    Gaenswein, Bernhard

    1987-09-01

    The crystals used in excimer lasers because of their excellent optical properties in the ultra violet spectrum are described. The crystals are fluorides of the alkaline earth metals magnesium, calcium and barium and the alkaline fluorides of lithium and sodium. It is possible to grow optical monocrystals of these compounds up to weights of 15 kg with a diameter of 180 mm. Some problems develop in growing crystals larger than this. To do so greater plants and improved automatic temperature monitoring and regulation are required. Special tools are needed for handling such large and heavy monocrystals. Understanding of the interaction between laser radiation and crystal must be improved upon in order to meet all the requirements to be placed on optical components in the future.

  14. Cholesteric liquid crystal photonic crystal lasers and photonic devices

    NASA Astrophysics Data System (ADS)

    Zhou, Ying

    This dissertation discusses cholesteric liquid crystals (CLCs) and polymers based photonic devices including one-dimensional (1D) photonic crystal lasers and broadband circular polarizers. CLCs showing unique self-organized chiral structures have been widely used in bistable displays, flexible displays, and reflectors. However, the photonic band gap they exhibit opens a new way for generating laser light at the photonic band edge (PBE) or inside the band gap. When doped with an emissive laser dye, cholesteric liquid crystals provide distributed feedback so that mirrorless lasing is hence possible. Due to the limited surface anchoring, the thickness of gain medium and feedback length is tens of micrometers. Therefore lasing efficiency is quite limited and laser beam is highly divergent. To meet the challenges, we demonstrated several new methods to enhance the laser emission while reducing the beam divergence from a cholesteric liquid crystal laser. Enhanced laser emission is demonstrated by incorporating a single external CLC reflector as a polarization conserved reflector. Because the distributed feedback from the active layer is polarization selective, a CLC reflector preserves the original polarization of the reflected light and a further stimulated amplification ensues. As a result of virtually doubled feedback length, the output is dramatically enhanced in the same circular polarization state. Meanwhile, the laser beam divergence is dramatically reduced due to the increased cavity length from micrometer to millimeter scale. Enhanced laser emission is also demonstrated by the in-cell metallic reflector because the active layer is pumped twice. Unlike a CLC reflector, the output from a mirror-reflected CLC laser is linearly polarized as a result of coherent superposition of two orthogonal circular polarization states. The output linear polarization direction can be well controlled and fine tuned by varying the operating temperature and cell gap. Enhanced laser

  15. Photonic quasi-crystal terahertz lasers

    NASA Astrophysics Data System (ADS)

    Vitiello, Miriam Serena; Nobile, Michele; Ronzani, Alberto; Tredicucci, Alessandro; Castellano, Fabrizio; Talora, Valerio; Li, Lianhe; Linfield, Edmund H.; Davies, A. Giles

    2014-12-01

    Quasi-crystal structures do not present a full spatial periodicity but are nevertheless constructed starting from deterministic generation rules. When made of different dielectric materials, they often possess fascinating optical properties, which lie between those of periodic photonic crystals and those of a random arrangement of scatterers. Indeed, they can support extended band-like states with pseudogaps in the energy spectrum, but lacking translational invariance, they also intrinsically feature a pattern of ‘defects’, which can give rise to critically localized modes confined in space, similar to Anderson modes in random structures. If used as laser resonators, photonic quasi-crystals open up design possibilities that are simply not possible in a conventional periodic photonic crystal. In this letter, we exploit the concept of a 2D photonic quasi crystal in an electrically injected laser; specifically, we pattern the top surface of a terahertz quantum-cascade laser with a Penrose tiling of pentagonal rotational symmetry, reaching 0.1-0.2% wall-plug efficiencies and 65 mW peak output powers with characteristic surface-emitting conical beam profiles, result of the rich quasi-crystal Fourier spectrum.

  16. Photonic quasi-crystal terahertz lasers

    PubMed Central

    Vitiello, Miriam Serena; Nobile, Michele; Ronzani, Alberto; Tredicucci, Alessandro; Castellano, Fabrizio; Talora, Valerio; Li, Lianhe; Linfield, Edmund H.; Davies, A. Giles

    2014-01-01

    Quasi-crystal structures do not present a full spatial periodicity but are nevertheless constructed starting from deterministic generation rules. When made of different dielectric materials, they often possess fascinating optical properties, which lie between those of periodic photonic crystals and those of a random arrangement of scatterers. Indeed, they can support extended band-like states with pseudogaps in the energy spectrum, but lacking translational invariance, they also intrinsically feature a pattern of ‘defects’, which can give rise to critically localized modes confined in space, similar to Anderson modes in random structures. If used as laser resonators, photonic quasi-crystals open up design possibilities that are simply not possible in a conventional periodic photonic crystal. In this letter, we exploit the concept of a 2D photonic quasi crystal in an electrically injected laser; specifically, we pattern the top surface of a terahertz quantum-cascade laser with a Penrose tiling of pentagonal rotational symmetry, reaching 0.1–0.2% wall-plug efficiencies and 65 mW peak output powers with characteristic surface-emitting conical beam profiles, result of the rich quasi-crystal Fourier spectrum. PMID:25523102

  17. Examining Crystals with the Use of a Laser.

    ERIC Educational Resources Information Center

    Koultras, Stratakus

    1993-01-01

    Presents three demonstrations that can help teachers explain crystal properties. The equipment used includes a laser, quartz crystals, and chalk dust. The laser light enables students to observe characteristics of structure that cannot be made with white light. (DDR)

  18. Ultrashort pulse laser slicing of semiconductor crystal

    NASA Astrophysics Data System (ADS)

    Kim, Eunho; Shimotsuma, Yasuhiko; Sakakura, Masaaki; Miura, Kiyotaka

    2016-07-01

    Meanwhile, by the convention wire-saw technique, it is difficult to slice off a thin wafer from bulk SiC crystal without the reserving space for cutting. In this study, we have achieved exfoliation of 4H-SiC single crystal by femtosecond laser induced slicing method. By using this, the exfoliated surface with the root-mean-square roughness of 3 μm and the cutting-loss thickness smaller than 30 μm was successfully demonstrated. We have also observed the nanostructure on the exfoliated surface in SiC crystal.

  19. Pulsed quantum-cascade laser-based sensor for trace-gas detection of carbonyl sulfide.

    PubMed

    Wysocki, Gerard; McCurdy, Matt; So, Stephen; Weidmann, Damien; Roller, Chad; Curl, Robert F; Tittel, Frank K

    2004-11-10

    Simultaneous exhaled carbonyl sulfide (OCS) and carbon dioxide concentration measurements in human breath are demonstrated with a compact pulsed quantum-cascade laser-based gas sensor. We achieved a noise-equivalent sensitivity (1sigma) of 1.2 parts per billion by measuring a well-isolated OCS P(11) absorption line in the v3 band at 2057.6 cm(-1) using an astigmatic Herriott cell of 36-m optical path length and 0.4-s acquisition time.

  20. Laser damage resistant nematic liquid crystal cell

    NASA Astrophysics Data System (ADS)

    Raszewski, Z.; Piecek, W.; Jaroszewicz, L.; Soms, L.; Marczak, J.; Nowinowski-Kruszelnicki, E.; Perkowski, P.; Kedzierski, J.; Miszczyk, E.; Olifierczuk, M.; Morawiak, P.; Mazur, R.

    2013-08-01

    There exists a problem in diagnostics of a dense plasma (so-called Thomson diagnostics). For this purpose, the plasma is illuminated by series of high energy laser pulses. Such pulses are generated by several independent lasers operating sequentially, and these pulses are to be directed along an exactly the same optical path. In this case, the energy of each separate pulse is as large as 3 J, so it is impossible to generate a burst of such pulses by a single laser. In this situation, several independent lasers have to be used. To form optical path with λ = 1.064 μm and absolute value of the energy of laser pulse through of 3 J, a special refractive index matched twisted Nematic Liquid Crystal Cell (NLCC) of type LCNP2 with switching on time τON smaller than 5 μs might be applied. High laser damage resistance of NLCC and short τON can be fulfilled by preparation of liquid crystal cells with Liquid Crystal Mixture (LCM), well tuned to twisted nematic electro-optical effect, and well tuned all optical interfaces (Air - Antireflection - Quartz Plate - Electrode - Blocking Film - Aligning Layer - LCM - Aligning Layer - Blocking Film - Electrode - Quartz Plate - Antireflection - Air). In such LCNP2 cell, the transmission is higher than 97% at λ = 1.064 μm, as it is presented by Gooch and Tarry [J. Phys. D: Appl. Phys. 8, 1575 (1975)]. The safe laser density energy is about 0.6 J/cm2 for a train of laser pulses (λ = 1.064 μm, pulse duration 10 ns FWHM, pulse repetition rate 100 pps, train duration 10 s), so the area of liquid crystal cell tolerating 3 J through it shall be as large as 5 cm2. Due to the presence of two blocking film layers between electrodes, LCNP2 can be driven by high voltages. Switching on time smaller than τON = 5 μs was obtained under 200 V switching voltage.

  1. IR laser-induced protein crystal transformation

    SciTech Connect

    Kiefersauer, Reiner Grandl, Brigitte; Krapp, Stephan; Huber, Robert

    2014-05-01

    A novel method and the associated instrumentation for improving crystalline order (higher resolution of X-ray diffraction and reduced mosaicity) of protein crystals by precisely controlled heating is demonstrated. Crystal transformation is optically controlled by a video system. A method and the design of instrumentation, and its preliminary practical realisation, including test experiments, with the object of inducing phase changes of biomolecular crystals by controlled dehydration through heating with infrared (IR) light are described. The aim is to generate and select crystalline phases through transformation in the solid state which have improved order (higher resolution in X-ray diffraction experiments) and reduced mosaic spread (more uniformly aligned mosaic blocks) for diffraction data collection and analysis. The crystal is heated by pulsed and/or constant IR laser irradiation. Loss of crystal water following heating and its reabsorption through equilibration with the environment is measured optically by a video system. Heating proved superior to traditional controlled dehydration by humidity change for the test cases CODH (carbon monoxide dehydrogenase) and CLK2 (a protein kinase). Heating with IR light is experimentally simple and offers an exploration of a much broader parameter space than the traditional method, as it allows the option of varying the rate of phase changes through modification of the IR pulse strength, width and repeat frequency. It impacts the crystal instantaneously, isotropically and homogeneously, and is therefore expected to cause less mechanical stress.

  2. New Mid-IR Lasers Based on Rare-Earth-Doped Sulfide and Chloride Materials

    SciTech Connect

    Nostrand, M

    2000-09-01

    Applications in remote-sensing and military countermeasures have driven a need for compact, solid-state mid-IR lasers. Due to multi-phonon quenching, non-traditional hosts are needed to extend current solid-state, room-temperature lasing capabilities beyond {approx} 4 {micro}m. Traditional oxide and fluoride hosts have effective phonon energies in the neighborhood of 1000 cm{sup -1} and 500 cm{sup -1}, respectively. These phonons can effectively quench radiation above 2 and 4 {micro}m, respectively. Materials with lower effective phonon energies such as sulfides and chlorides are the logical candidates for mid-IR (4-10 {micro}m) operation. In this report, laser action is demonstrated in two such hosts, CaGa{sub 2}S{sub 4} and KPb{sub 2}Cl{sub 5}. The CaGa{sub 2}S{sub 4}:Dy{sup 3+} laser operating at 4.3 {micro}m represents the first sulfide laser operating beyond 2 {micro}m. The KPb{sub 2}Cl{sub 5}:Dy{sup 3+} laser operating at 2.4 {micro}m represents the first operation of a chloride-host laser in ambient conditions. Laser action is also reported for CaGa{sub 2}S{sub 4}:Dy{sup 3+} at 2.4 {micro}m, CaGa{sub 2}S{sub 4}:Dy{sup 3+} at 1.4 {micro}m, and KPb{sub 2}Cl{sub 5}:Nd{sup 3+} at 1.06 {micro}m. Both host materials have been fully characterized, including lifetimes, absorption and emission cross sections, radiative branching ratios, and radiative quantum efficiencies. Radiative branching ratios and radiative quantum efficiencies have been determined both by the Judd-Ofelt method (which is based on absorption measurements), and by a novel method described herein which is based on emission measurements. Modeling has been performed to predict laser performance, and a new method to determine emission cross section from slope efficiency and threshold data is developed. With the introduction and laser demonstration of rare-earth-doped CaGa{sub 2}S{sub 4} and KPb{sub 2}Cl{sub 5}, direct generation of mid-IR laser radiation in a solid-state host has been demonstrated. In

  3. Sulfide binding is mediated by zinc ions discovered in the crystal structure of a hydrothermal vent tubeworm hemoglobin.

    PubMed

    Flores, Jason F; Fisher, Charles R; Carney, Susan L; Green, Brian N; Freytag, John K; Schaeffer, Stephen W; Royer, William E

    2005-02-22

    Key to the remarkable ability of vestimentiferan tubeworms to thrive in the harsh conditions of hydrothermal vents are hemoglobins that permit the sequestration and delivery of hydrogen sulfide and oxygen to chemoautotrophic bacteria. Here, we demonstrate that zinc ions, not free cysteine residues, bind sulfide in vestimentiferan hemoglobins. The crystal structure of the C1 hemoglobin from the hydrothermal vent tubeworm Riftia pachyptila has been determined to 3.15 A and revealed the unexpected presence of 12 tightly bound Zn(2+) ions near the threefold axes of this D(3) symmetric hollow sphere. Chelation experiments on R. pachyptila whole-coelomic fluid and purified hemoglobins reveal a role for Zn(2+) ions in sulfide binding. Free cysteine residues, previously proposed as sulfide-binding sites in vestimentiferan hemoglobins, are found buried in surprisingly hydrophobic pockets below the surface of the R. pachyptila C1 molecule, suggesting that access of these residues to environmental sulfide is restricted. Attempts to reduce the sulfide-binding capacities of R. pachyptila hemoglobins by addition of a thiol inhibitor were also unsuccessful. These findings challenge the currently accepted paradigm of annelid hemoglobin evolution and adaptation to reducing environments. PMID:15710902

  4. Semiconductor single crystal external ring resonator cavity laser and gyroscope

    SciTech Connect

    Spitzer, M.P.

    1993-08-31

    A ring laser is described comprising: a semiconductor single crystal external ring resonator cavity having a plurality of reflecting surfaces defined by the planes of the crystal and establishing a closed optical path; and a discrete laser medium disposed in said semiconductor single crystal external ring resonator cavity for generating coherent light in said cavity, wherein said resonator cavity is decoupled from the laser medium.

  5. IR laser-induced protein crystal transformation.

    PubMed

    Kiefersauer, Reiner; Grandl, Brigitte; Krapp, Stephan; Huber, Robert

    2014-05-01

    A method and the design of instrumentation, and its preliminary practical realisation, including test experiments, with the object of inducing phase changes of biomolecular crystals by controlled dehydration through heating with infrared (IR) light are described. The aim is to generate and select crystalline phases through transformation in the solid state which have improved order (higher resolution in X-ray diffraction experiments) and reduced mosaic spread (more uniformly aligned mosaic blocks) for diffraction data collection and analysis. The crystal is heated by pulsed and/or constant IR laser irradiation. Loss of crystal water following heating and its reabsorption through equilibration with the environment is measured optically by a video system. Heating proved superior to traditional controlled dehydration by humidity change for the test cases CODH (carbon monoxide dehydrogenase) and CLK2 (a protein kinase). Heating with IR light is experimentally simple and offers an exploration of a much broader parameter space than the traditional method, as it allows the option of varying the rate of phase changes through modification of the IR pulse strength, width and repeat frequency. It impacts the crystal instantaneously, isotropically and homogeneously, and is therefore expected to cause less mechanical stress.

  6. Ionization of oriented carbonyl sulfide molecules by intense circularly polarized laser pulses

    SciTech Connect

    Dimitrovski, Darko; Abu-samha, Mahmoud; Madsen, Lars Bojer; Filsinger, Frank; Meijer, Gerard; Kuepper, Jochen; Holmegaard, Lotte; Kalhoej, Line; Nielsen, Jens H.; Stapelfeldt, Henrik

    2011-02-15

    We present combined experimental and theoretical results on strong-field ionization of oriented carbonyl sulfide molecules by circularly polarized laser pulses. The obtained molecular frame photoelectron angular distributions show pronounced asymmetries perpendicular to the direction of the molecular electric dipole moment. These findings are explained by a tunneling model invoking the laser-induced Stark shifts associated with the dipoles and polarizabilities of the molecule and its unrelaxed cation. The focus of the present article is to understand the strong-field ionization of one-dimensionally-oriented polar molecules, in particular asymmetries in the emission direction of the photoelectrons. In the following article [Phys. Rev. A 83, 023406 (2011)] the focus is to understand strong-field ionization from three-dimensionally-oriented asymmetric top molecules, in particular the suppression of electron emission in nodal planes of molecular orbitals.

  7. Transient Plasma Photonic Crystals for High-Power Lasers.

    PubMed

    Lehmann, G; Spatschek, K H

    2016-06-01

    A new type of transient photonic crystals for high-power lasers is presented. The crystal is produced by counterpropagating laser beams in plasma. Trapped electrons and electrically forced ions generate a strong density grating. The lifetime of the transient photonic crystal is determined by the ballistic motion of ions. The robustness of the photonic crystal allows one to manipulate high-intensity laser pulses. The scheme of the crystal is analyzed here by 1D Vlasov simulations. Reflection or transmission of high-power laser pulses are predicted by particle-in-cell simulations. It is shown that a transient plasma photonic crystal may act as a tunable mirror for intense laser pulses. Generalizations to 2D and 3D configurations are possible. PMID:27314721

  8. Transient Plasma Photonic Crystals for High-Power Lasers

    NASA Astrophysics Data System (ADS)

    Lehmann, G.; Spatschek, K. H.

    2016-06-01

    A new type of transient photonic crystals for high-power lasers is presented. The crystal is produced by counterpropagating laser beams in plasma. Trapped electrons and electrically forced ions generate a strong density grating. The lifetime of the transient photonic crystal is determined by the ballistic motion of ions. The robustness of the photonic crystal allows one to manipulate high-intensity laser pulses. The scheme of the crystal is analyzed here by 1D Vlasov simulations. Reflection or transmission of high-power laser pulses are predicted by particle-in-cell simulations. It is shown that a transient plasma photonic crystal may act as a tunable mirror for intense laser pulses. Generalizations to 2D and 3D configurations are possible.

  9. Ultraviolet laser beam monitor using radiation responsive crystals

    DOEpatents

    McCann, Michael P.; Chen, Chung H.

    1988-01-01

    An apparatus and method for monitoring an ultraviolet laser beam includes disposing in the path of an ultraviolet laser beam a substantially transparent crystal that will produce a color pattern in response to ultraviolet radiation. The crystal is exposed to the ultraviolet laser beam and a color pattern is produced within the crystal corresponding to the laser beam intensity distribution therein. The crystal is then exposed to visible light, and the color pattern is observed by means of the visible light to determine the characteristics of the laser beam that passed through crystal. In this manner, a perpendicular cross sectional intensity profile and a longitudinal intensity profile of the ultraviolet laser beam may be determined. The observation of the color pattern may be made with forward or back scattered light and may be made with the naked eye or with optical systems such as microscopes and television cameras.

  10. 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.

  11. Nucleation and crystal growth in laser patterned lines in glasses

    NASA Astrophysics Data System (ADS)

    Komatsu, Takayuki; Honma, Tsuyoshi

    2016-07-01

    Laser-induced crystallization is a new method for the design and control of the crystallization of glasses and opens a new door in the study of nucleation and crystal growth in glasses. Nonlinear optical Sm-doped -BaB2O4 (-BBO) crystal lines were patterned by continuous wave Yb:YVO4 fiber laser (wavelength 1080 nm) in 8Sm2O3-42BaO-50B2O3 glass as an example, and nucleation and crystal growth behaviors in the laser-patterned bending and crossing lines were examined. It was confirmed that the growth of c-axis oriented -BBO crystals follows along the laser scanning direction even if laser scanning direction changes. The model of self-organized homo-epitaxial crystal growth was demonstrated for the orientation of -BBO crystals at the crossing point of two lines, in which the first crystal line at the crossing point acts as nucleation site for the second crystal line. This study proposes a new crystal growth technology.

  12. In situ AFM observations of Ca-Mg carbonate crystallization catalyzed by dissolved sulfide: Implications for sedimentary dolomite formation

    NASA Astrophysics Data System (ADS)

    Zhang, Fangfu; Yan, Chao; Teng, H. Henry; Roden, Eric E.; Xu, Huifang

    2013-03-01

    It has been observed that the metabolism of sulfate-reducing bacteria can overcome the energy barrier to Mg2+ incorporation into growing Ca-Mg carbonates and enhance dolomite precipitation, although the role of SRB in dolomite formation is still under debate. In this study, we presented in situ AFM observations of Ca-Mg carbonate {1 0 4} surface growing from supersaturated solutions. Our data showed that not only can Mg2+ modify the morphology of the polygonal growth hillocks and impede step growth, but it can also inhibit 1-D step nucleation, resulting in the inability for spirals to continue their vertical growth. However, in the presence of dissolved sulfide, both the 1-D step nucleation and step growth which had been retarded by Mg2+ ions were significantly enhanced. For example, in the presence as low as 0.13 mM dissolved sulfide, the step velocity can be increased by more than 9 times compared to that in contact with solutions containing Mg2+ ions but no dissolved sulfide. The Ca-Mg carbonate growth hillock in contact with dissolved sulfide-bearing growth solutions eventually developed a micromosaic-like structure. Based on our observations, we propose that the overall catalytic effect of dissolved sulfide may be twofold, one to stabilize the critical nuclei during 1-D step nucleation by the adsorption of dissolved sulfide on Ca-Mg carbonate surfaces and two to facilitate the dehydration of surface Mg2+-water complexes during growth. We hypothesize that dissolved sulfide may adsorb on crystal faces through hydrogen bonding between the H in HS-/H2S and the O in calcite CO32- to weaken the rigid Mg2+ hydration shell, resulting in an elevated activation entropy for particle attachment and hence a larger kinetic coefficient for step growth. Together with previous studies on disorder dolomite precipitation induced by dissolved sulfide, we demonstrate the catalysis role of dissolved sulfide in sedimentary dolomite formation associate with SRB, which may shed new

  13. Method for reducing energy losses in laser crystals

    DOEpatents

    Atherton, L.J.; DeYoreo, J.J.; Roberts, D.H.

    1992-03-24

    A process for reducing energy losses in crystals is disclosed which comprises: a. heating a crystal to a temperature sufficiently high as to cause dissolution of microscopic inclusions into the crystal, thereby converting said inclusions into point-defects, and b. maintaining said crystal at a given temperature for a period of time sufficient to cause said point-defects to diffuse out of said crystal. Also disclosed are crystals treated by the process, and lasers utilizing the crystals as a source of light. 12 figs.

  14. Method for reducing energy losses in laser crystals

    DOEpatents

    Atherton, L. Jeffrey; DeYoreo, James J.; Roberts, David H.

    1992-01-01

    A process for reducing energy losses in crystals is disclosed which comprises: a. heating a crystal to a temperature sufficiently high as to cause dissolution of microscopic inclusions into the crystal, thereby converting said inclusions into point-defects, and b. maintaining said crystal at a given temperature for a period of time sufficient to cause said point-defects to diffuse out of said crystal. Also disclosed are crystals treated by the process, and lasers utilizing the crystals as a source of light.

  15. Photonic Crystal Laser-Driven Accelerator Structures

    SciTech Connect

    Cowan, Benjamin M.

    2007-08-22

    Laser-driven acceleration holds great promise for significantly improving accelerating gradient. However, scaling the conventional process of structure-based acceleration in vacuum down to optical wavelengths requires a substantially different kind of structure. We require an optical waveguide that (1) is constructed out of dielectric materials, (2) has transverse size on the order of a wavelength, and (3) supports a mode with speed-of-light phase velocity in vacuum. Photonic crystals---structures whose electromagnetic properties are spatially periodic---can meet these requirements. We discuss simulated photonic crystal accelerator structures and describe their properties. We begin with a class of two-dimensional structures which serves to illustrate the design considerations and trade-offs involved. We then present a three-dimensional structure, and describe its performance in terms of accelerating gradient and efficiency. We discuss particle beam dynamics in this structure, demonstrating a method for keeping a beam confined to the waveguide. We also discuss material and fabrication considerations. Since accelerating gradient is limited by optical damage to the structure, the damage threshold of the dielectric is a critical parameter. We experimentally measure the damage threshold of silicon for picosecond pulses in the infrared, and determine that our structure is capable of sustaining an accelerating gradient of 300 MV/m at 1550 nm. Finally, we discuss possibilities for manufacturing these structures using common microfabrication techniques.

  16. Blue shift of laser mode in photonic crystal microcavity

    NASA Astrophysics Data System (ADS)

    Zhao, Pengchao; Feng, Z. G.; Qi, Fan; Qi, Aiyi; Wang, Yufei; Zheng, W. H.

    2014-11-01

    We report the first demonstration of blue shift of optical pumping photonic crystal (PhC) laser. A femtosecond laser was used to pump the InGaAsP based two dimensional photonic crystal laser at room temperature. Linear dependence of the resonance wavelength with respect to the pump power is observed: dλ/dP=-1.5×10-2 nm/μW . Blue shift of overall 1.1nm was obtained with the increase power of pump laser. These results are in agreement with theoretical expectation while the carrier-induced index change is introduced into the PhC semiconductor laser. It shows a possibility that by proper wafer design and careful optimization, we may obtain wavelength stable photonic crystal laser, which is important in photonic integration.

  17. A liquid crystal-based passive badge for personal monitoring of exposure to hydrogen sulfide.

    PubMed

    Robinson, Sheila E; Grinwald, Bart A; Bremer, Laura L; Kupcho, Kurt A; Acharya, Bharat R; Owens, Patrick D

    2014-01-01

    A new liquid crystal (LC)-based passive dosimeter badge for personal monitoring of exposure to hydrogen sulfide (H2S) gas is reported. When a thin film of LC supported on a surface functionalized with lead perchlorate Pb(ClO4)2 (the LC sensor) is exposed to H2S, the orientation of LC molecules in the film changes from perpendicular to parallel. This reorientation induces a change in the appearance of the LC film when viewed between crossed polarizers. A H2S dosimeter was fabricated by pairing a LC sensor with a glass substrate forming a headspace between the two surfaces, to control diffusion of H2S across the LC film. When the dosimeter is exposed to H2S, a bright front appears as a function of exposure time. An algorithm has been developed to correlate this response length and exposure dose. The dosimeters are functionally stable when subjected to extreme temperature and humidity fluctuations, and are immune to a number of potentially interfering chemicals, except mercaptans. These dosimeters detect H2S at 0.2 ppm TWA (8 hr) with ±20% overall accuracy. The dosimeters were used to monitor the personal exposure of personnel working in an oil refinery. The TWA concentrations measured by the LC-based dosimeters correlate strongly with the NIOSH 1063 method that uses a sorbent tube and a pump followed by laboratory analysis. Thus, the LC-based dosimeters can provide a sensitive tool for on-site assessment of personal exposure to H2S in different environments. PMID:24766440

  18. A liquid crystal-based passive badge for personal monitoring of exposure to hydrogen sulfide.

    PubMed

    Robinson, Sheila E; Grinwald, Bart A; Bremer, Laura L; Kupcho, Kurt A; Acharya, Bharat R; Owens, Patrick D

    2014-01-01

    A new liquid crystal (LC)-based passive dosimeter badge for personal monitoring of exposure to hydrogen sulfide (H2S) gas is reported. When a thin film of LC supported on a surface functionalized with lead perchlorate Pb(ClO4)2 (the LC sensor) is exposed to H2S, the orientation of LC molecules in the film changes from perpendicular to parallel. This reorientation induces a change in the appearance of the LC film when viewed between crossed polarizers. A H2S dosimeter was fabricated by pairing a LC sensor with a glass substrate forming a headspace between the two surfaces, to control diffusion of H2S across the LC film. When the dosimeter is exposed to H2S, a bright front appears as a function of exposure time. An algorithm has been developed to correlate this response length and exposure dose. The dosimeters are functionally stable when subjected to extreme temperature and humidity fluctuations, and are immune to a number of potentially interfering chemicals, except mercaptans. These dosimeters detect H2S at 0.2 ppm TWA (8 hr) with ±20% overall accuracy. The dosimeters were used to monitor the personal exposure of personnel working in an oil refinery. The TWA concentrations measured by the LC-based dosimeters correlate strongly with the NIOSH 1063 method that uses a sorbent tube and a pump followed by laboratory analysis. Thus, the LC-based dosimeters can provide a sensitive tool for on-site assessment of personal exposure to H2S in different environments.

  19. Cadmium sulfide membranes

    DOEpatents

    Spanhel, Lubomir; Anderson, Marc A.

    1992-07-07

    A method is described for the creation of novel q-effect cadmium sulfide membranes. The membranes are made by first creating a dilute cadmium sulfide colloid in aqueous suspension and then removing the water and excess salts therefrom. The cadmium sulfide membrane thus produced is luminescent at room temperature and may have application in laser fabrication.

  20. Cadmium sulfide membranes

    DOEpatents

    Spanhel, Lubomir; Anderson, Marc A.

    1991-10-22

    A method is described for the creation of novel q-effect cadmium sulfide membranes. The membranes are made by first creating a dilute cadmium sulfide colloid in aqueous suspension and then removing the water and excess salts therefrom. The cadmium sulfide membrane thus produced is luminescent at room temperature and may have application in laser fabrication.

  1. Assessment of carbon fiber-reinforced polyphenylene sulfide by means of laser ultrasound

    NASA Astrophysics Data System (ADS)

    Kalms, Michael; Peters, Christian; Wierbos, Ronald

    2011-04-01

    From automobile industry to aerospace, thermoformed composites are more and more in use. Thermoplastics offer a number of attractive applications in commercial use like short production times, tailored solutions, recyclability and lower cost. The thermoforming process allows for producing carbon fiber-reinforced parts in a wide range of different geometric shapes. On the other hand this benefit requires a demanding nondestructive testing procedure especially for security relevant parts. A contactless method which is able to fulfil this requirement is the extension of the ultrasound technique with laser technology. It opens up new opportunities for quality assessment during manufacturing like inspection of complex surfaces including small radii, remote observation and nondestructive testing of hot items directly after the thermal forming process. We describe the successful application of laser-based ultrasound on small complex thermoformed composite parts (Cetex® PPS). Cetex consists of semicrystalline polyphenylene sulfide thermoplastics providing outstanding toughness and excellent chemical and solvent resistance. It is qualified in aircraft industry for multiple structural applications. For instance, Cetex is used in the Airbus A380 engine air intakes and the wing fixed leading edge (J-Nose). We investigated several test samples with intentionally introduced defects. The smallest flaw size detected was 2 mm in diameter for delaminations and 6 mm in diameter for porosity.

  2. Polycrystalline silicon thin films crystallized by green laser

    NASA Astrophysics Data System (ADS)

    Yuan, Zhijun; Lou, Qihong; Zhou, Jun; Liu, Xia; Wang, Wei; Su, Zhouping

    2008-12-01

    A top hat beam of frequency-doubled Nd: YAG laser is obtained from our beam shaping optical system. With this beam, amorphous silicon thin films deposited on glass by plasma-enhanced chemical vapor deposition (PECVD) are successfully crystallized. The surface morphology of the laser-crystallized materials is studied by atomic force microscopy (AFM). Pronounced increase in surface roughness after the laser treatment could be observed from the Microscope Photos. Raman spectra of the Si films are measured to confirm the phase transition from amorphous to polycrystalline and to investigate the silicon structural properties. Crystalline fraction evaluated from the Raman spectra are found to increase almost linearly with the laser fluence. There exists the optimized laser fluence to produce the best crystallization in the range of 400 ~1000mJ/cm2.

  3. Automated harvesting and processing of protein crystals through laser photoablation.

    PubMed

    Zander, Ulrich; Hoffmann, Guillaume; Cornaciu, Irina; Marquette, Jean-Pierre; Papp, Gergely; Landret, Christophe; Seroul, Gaël; Sinoir, Jérémy; Röwer, Martin; Felisaz, Frank; Rodriguez-Puente, Sonia; Mariaule, Vincent; Murphy, Peter; Mathieu, Magali; Cipriani, Florent; Márquez, José Antonio

    2016-04-01

    Currently, macromolecular crystallography projects often require the use of highly automated facilities for crystallization and X-ray data collection. However, crystal harvesting and processing largely depend on manual operations. Here, a series of new methods are presented based on the use of a low X-ray-background film as a crystallization support and a photoablation laser that enable the automation of major operations required for the preparation of crystals for X-ray diffraction experiments. In this approach, the controlled removal of the mother liquor before crystal mounting simplifies the cryocooling process, in many cases eliminating the use of cryoprotectant agents, while crystal-soaking experiments are performed through diffusion, precluding the need for repeated sample-recovery and transfer operations. Moreover, the high-precision laser enables new mounting strategies that are not accessible through other methods. This approach bridges an important gap in automation and can contribute to expanding the capabilities of modern macromolecular crystallography facilities. PMID:27050125

  4. Automated harvesting and processing of protein crystals through laser photoablation

    PubMed Central

    Zander, Ulrich; Hoffmann, Guillaume; Cornaciu, Irina; Marquette, Jean-Pierre; Papp, Gergely; Landret, Christophe; Seroul, Gaël; Sinoir, Jérémy; Röwer, Martin; Felisaz, Frank; Rodriguez-Puente, Sonia; Mariaule, Vincent; Murphy, Peter; Mathieu, Magali; Cipriani, Florent; Márquez, José Antonio

    2016-01-01

    Currently, macromolecular crystallography projects often require the use of highly automated facilities for crystallization and X-ray data collection. However, crystal harvesting and processing largely depend on manual operations. Here, a series of new methods are presented based on the use of a low X-ray-background film as a crystallization support and a photoablation laser that enable the automation of major operations required for the preparation of crystals for X-ray diffraction experiments. In this approach, the controlled removal of the mother liquor before crystal mounting simplifies the cryocooling process, in many cases eliminating the use of cryoprotectant agents, while crystal-soaking experiments are performed through diffusion, precluding the need for repeated sample-recovery and transfer operations. Moreover, the high-precision laser enables new mounting strategies that are not accessible through other methods. This approach bridges an important gap in automation and can contribute to expanding the capabilities of modern macromolecular crystallography facilities. PMID:27050125

  5. A nano-patterned photonic crystal laser with a dye-doped liquid crystal

    NASA Astrophysics Data System (ADS)

    Ko, Doo-Hyun; Morris, Stephen M.; Lorenz, Alexander; Castles, Flynn; Butt, Haider; Gardiner, Damian J.; Qasim, Malik M.; Wallikewitz, Bodo; Hands, Philip J. W.; Wilkinson, Timothy D.; Amaratunga, Gehan A. J.; Coles, Harry J.; Friend, Richard H.

    2013-07-01

    Covering a nano-patterned titanium dioxide photonic crystal (PC) within a well-oriented film of dye-doped liquid crystal (LC), a distributed feedback laser is constructed whereby the emission characteristics can be manipulated in-situ using an electric field. This hybrid organic-inorganic structure permits simultaneous selectivity of both the beam pattern and laser wavelength by electrical addressing of the LC director. In addition, laser emission is obtained both in the plane and normal to the PC. Along with experimental data, a theoretical model is presented that is based upon an approximate calculation of the band structure of this birefringent, tuneable laser device.

  6. Hollow-core photonic-crystal fibres for laser dentistry

    NASA Astrophysics Data System (ADS)

    Konorov, Stanislav O.; Mitrokhin, Vladimir P.; Fedotov, Andrei B.; Sidorov-Biryukov, Dmitrii A.; Beloglazov, Valentin I.; Skibina, Nina B.; Wintner, Ernst; Scalora, Michael; Zheltikov, Aleksei M.

    2004-04-01

    Hollow-core photonic-crystal fibres (PCFs) for the delivery of high-fluence laser radiation capable of ablating tooth enamel are developed. Sequences of picosecond pulses of 1.06 µm Nd:YAG-laser radiation with a total energy of about 2 mJ are transmitted through a hollow-core photonic-crystal fibre with a core diameter of approximately 14 µm and are focused on a tooth surface in vitro to ablate dental tissue. The hollow-core PCF is shown to support the single-fundamental-mode regime for 1.06 µm laser radiation, serving as a spatial filter and allowing the laser beam quality to be substantially improved. The same fibre is used to transmit emission from plasmas produced by laser pulses on the tooth surface in the backward direction for detection and optical diagnostics.

  7. Crystal growth and application of large size YCOB crystal for high power laser

    NASA Astrophysics Data System (ADS)

    Wu, Anhua; Xu, Jun; Zheng, Yanqing; Liang, Xiaoyan

    2014-10-01

    Yttrium calcium oxyborate YCa4O(BO3)3 (YCOB) is a novel non-linear optical crystal possessing good thermal, mechanical and nonlinear optical properties. It is regards the important candidate frequency conversion material for the high-average power laser system. In this work, we described our effort to achieve the successful growth of large size YCOB single crystals, and the crystal quality of large size YCOB crystal grown by the Bridgman method. The OPCPA application of YCOB element was also introduced simply. The results confirmed that Bridgman technology can be used for the growth of large size YCOB crystal as an alternative to Czochralski method.

  8. Threshold Characteristics of Slow-Light Photonic Crystal Lasers.

    PubMed

    Xue, Weiqi; Yu, Yi; Ottaviano, Luisa; Chen, Yaohui; Semenova, Elizaveta; Yvind, Kresten; Mork, Jesper

    2016-02-12

    The threshold properties of photonic crystal quantum dot lasers operating in the slow-light regime are investigated experimentally and theoretically. Measurements show that, in contrast to conventional lasers, the threshold gain attains a minimum value for a specific cavity length. The experimental results are explained by an analytical theory for the laser threshold that takes into account the effects of slow light and random disorder due to unavoidable fabrication imperfections. Longer lasers are found to operate deeper into the slow-light region, leading to a trade-off between slow-light induced reduction of the mirror loss and slow-light enhancement of disorder-induced losses. PMID:26918991

  9. Threshold Characteristics of Slow-Light Photonic Crystal Lasers

    NASA Astrophysics Data System (ADS)

    Xue, Weiqi; Yu, Yi; Ottaviano, Luisa; Chen, Yaohui; Semenova, Elizaveta; Yvind, Kresten; Mork, Jesper

    2016-02-01

    The threshold properties of photonic crystal quantum dot lasers operating in the slow-light regime are investigated experimentally and theoretically. Measurements show that, in contrast to conventional lasers, the threshold gain attains a minimum value for a specific cavity length. The experimental results are explained by an analytical theory for the laser threshold that takes into account the effects of slow light and random disorder due to unavoidable fabrication imperfections. Longer lasers are found to operate deeper into the slow-light region, leading to a trade-off between slow-light induced reduction of the mirror loss and slow-light enhancement of disorder-induced losses.

  10. Crystal structure of laser-induced subsurface modifications in Si

    SciTech Connect

    Verburg, P. C.; Smillie, L. A.; Römer, G. R. B. E.; Haberl, B.; Bradby, J. E.; Williams, J. S.; Huis in ’t Veld, A. J.

    2015-06-04

    Laser-induced subsurface modification of dielectric materials is a well-known technology. Applications include the production of optical components and selective etching. In addition to dielectric materials, the subsurface modification technology can be applied to silicon, by employing near to mid-infrared radiation. An application of subsurface modifications in silicon is laser-induced subsurface separation, which is a method to separate wafers into individual dies. Other applications for which proofs of concept exist are the formation of waveguides and resistivity tuning. However, limited knowledge is available about the crystal structure of subsurface modifications in silicon. In this paper, we investigate the geometry and crystal structure of laser-induced subsurface modifications in monocrystalline silicon wafers. Finally, in addition to the generation of lattice defects, we found that transformations to amorphous silicon and Si-iii/Si-xii occur as a result of the laser irradiation.

  11. Eddy covariance carbonyl sulfide flux measurements with a quantum cascade laser absorption spectrometer

    NASA Astrophysics Data System (ADS)

    Gerdel, Katharina; Spielmann, Felix M.; Hammerle, Albin; Wohlfahrt, Georg

    2016-04-01

    Carbonyl sulfide (COS) is the most abundant sulfur containing trace gas present in the troposphere at concentrations of around 500 ppt. Recent interest in COS by the ecosystem-physiological community has been sparked by the fact that COS co-diffuses into plant leaves pretty much the same way as carbon dioxide (CO2) does, but in contrast to CO2, COS is not known to be emitted by plants. Thus uptake of COS by vegetation has the potential to be used as a tracer for canopy gross photosynthesis, which cannot be measured directly, however represents a key term in the global carbon cycle. Since a few years, quantum cascade laser absorption spectrometers (QCLAS) are commercially available with the precision, sensitivity and time response suitable for eddy covariance (EC) flux measurements. While there exist a handful of published reports on EC flux measurements in the recent literature, no rigorous investigation of the applicability of QCLAS for EC COS flux measurements has been carried out so far, nor have been EC processing and QA/QC steps developed for carbon dioxide and water vapor flux measurements within FLUXNET been assessed for COS. The aim of this study is to close this knowledge gap, to discuss critical steps in the post-processing chain of COS EC flux measurements and to devise best-practice guidelines for COS EC flux data processing. To this end we collected EC COS (and CO2, H2O and CO) flux measurements above a temperate mountain grassland in Austria over the vegetation period 2015 with a commercially available QCLAS. We discuss various aspects of EC data post-processing, in particular issues with the time-lag estimation between sonic anemometer and QCLAS signals and QCLAS time series detrending, as well as QA/QC, in particular flux detection limits, random flux uncertainty, the interaction of various processing steps with common EC QA/QC filters (e.g. detrending and stationarity tests), u*-filtering, etc.

  12. Laser Crystallization of Organic-Inorganic Hybrid Perovskite Solar Cells.

    PubMed

    Jeon, Taewoo; Jin, Hyeong Min; Lee, Seung Hyun; Lee, Ju Min; Park, Hyung Il; Kim, Mi Kyung; Lee, Keon Jae; Shin, Byungha; Kim, Sang Ouk

    2016-08-23

    Organic-inorganic hybrid perovskites attract enormous research interest for next generation solar energy harvest. Synergistic crystalline structures comprising organic and inorganic components enable solution processing of perovskite films. A reliable crystallization method for perovskites, compatible with fast continuous process over large-area flexible substrates, is crucial for high performance solar cell production. Here, we present laser crystallization of hybrid perovskite solar cells using near-infrared (NIR) laser (λ = 1064 nm). Crystalline morphology of CH3NH3PbI3 (MAPbI3) perovskite films are widely controllable with laser irradiation condition while maintaining film uniformity. Photothermal heating effectively assisted by interfacial photoconversion layers is critical for phase transformation without beam damage of multilayered device structures. Notably, laser crystallization attains higher device performances than conventional thermal annealing. Fast laser crystallization with manufacture level scan rate (1 m min(-1)) demonstrates inverted-type perovskite solar cells with 11.3 and 8.0% efficiencies on typical glass and flexible polymer substrates, respectively, without rigorous device optimization.

  13. Laser Crystallization of Organic-Inorganic Hybrid Perovskite Solar Cells.

    PubMed

    Jeon, Taewoo; Jin, Hyeong Min; Lee, Seung Hyun; Lee, Ju Min; Park, Hyung Il; Kim, Mi Kyung; Lee, Keon Jae; Shin, Byungha; Kim, Sang Ouk

    2016-08-23

    Organic-inorganic hybrid perovskites attract enormous research interest for next generation solar energy harvest. Synergistic crystalline structures comprising organic and inorganic components enable solution processing of perovskite films. A reliable crystallization method for perovskites, compatible with fast continuous process over large-area flexible substrates, is crucial for high performance solar cell production. Here, we present laser crystallization of hybrid perovskite solar cells using near-infrared (NIR) laser (λ = 1064 nm). Crystalline morphology of CH3NH3PbI3 (MAPbI3) perovskite films are widely controllable with laser irradiation condition while maintaining film uniformity. Photothermal heating effectively assisted by interfacial photoconversion layers is critical for phase transformation without beam damage of multilayered device structures. Notably, laser crystallization attains higher device performances than conventional thermal annealing. Fast laser crystallization with manufacture level scan rate (1 m min(-1)) demonstrates inverted-type perovskite solar cells with 11.3 and 8.0% efficiencies on typical glass and flexible polymer substrates, respectively, without rigorous device optimization. PMID:27377145

  14. Suppression of excited-state absorption in laser crystals

    NASA Astrophysics Data System (ADS)

    Kuznetsova, Elena; Kolesov, Roman; Kocharovskaya, Olga

    2004-10-01

    Currently, a lot of experimental effort in solid-state optics is devoted to searching for laser materials suitable for tunable lasing, primarily in UV and VUV spectral regions. Researchers mainly focus on optical crystals doped with either transition metal or rare-earth ions. The latter ones doped into wide bandgap dielectric crystals have spectrally broad vibronic emission bands associated with 4fn-15d â" 4fn interconfigurational transitions, whose energies lie mostly in UV and VUV regions of the spectrum. The transitions are electric-dipole-allowed, therefore have large absorption and emission cross-sections, and are promising for efficient tunable laser action. However, in almost all promising crystals laser action in UV and VUV is hindered or completely prohibited due to excited-state absorption (ESA), i.e. absorption from metastable laser levels to higher-energy states, which occurs at emission or/and pump wavelengths. A method of suppression of losses due to excited-state absorption (ESA) in laser crystals is proposed, based on a well-known phenomenon of electromagnetically induced transparency (EIT). Absorption from a populated excited electronic state can be reduced under the action of an additional driving coherent field, resonantly coupling the terminal state of ESA to some intermediate discrete state.

  15. Channel waveguide lasers in Nd:LGS crystals.

    PubMed

    Ren, Yingying; Vázquez de Aldana, Javier R; Chen, Feng; Zhang, Huaijin

    2013-03-11

    Optical channel waveguides have been produced in Nd:LGS laser crystals by using ultrafast laser inscription with a depressed cladding configuration. The cross sectional shape of the cladding waveguides is circular, surrounded by low refractive index tracks, which makes the channel waveguides as three-dimensional tubular structures. Under optical pump of 810 nm light, continuous-wave waveguide lasers at 1068 nm have been achieved at room temperature, with minimum lasing threshold of 54 mW, a maximum slope efficiency of 24% and a maximum output power of 16 mW.

  16. Rare earth ion doped non linear laser crystals

    NASA Astrophysics Data System (ADS)

    Jaque, D.; Romero, J. J.; Ramirez, M. O.; Garcia, J. A. S.; de Las Heras, C.; Bausa, L. E.; Sole, J. G.

    2003-01-01

    We show how non linear crystals activated with Yb3+ or Nd3+ ions can be used to develop diode pumped solid state lasers emitting in the visible region of the electromagnetic spectrum. For this purpose we have selected relevant examples of systems investigated in our laboratory.

  17. Ytterbium- and neodymium-doped vanadate laser hose crystals having the apatite crystal structure

    DOEpatents

    Payne, S.A.; Kway, W.L.; DeLoach, L.D.; Krupke, W.F.; Chai, B.H.T.

    1994-08-23

    Yb[sup 3+] and Nd[sup 3+] doped Sr[sub 5](VO[sub 4])[sub 3]F crystals serve as useful infrared laser media that exhibit low thresholds of oscillation and high slope efficiencies, and can be grown with high optical quality. These laser media possess unusually high absorption and emission cross sections, which provide the crystals with the ability to generate greater gain for a given amount of pump power. Many related crystals such as Sr[sub 5](VO[sub 4])[sub 3]F crystals doped with other rare earths, transition metals, or actinides, as well as the many structural analogs of Sr[sub 5](VO[sub 4])[sub 3]F, where the Sr[sup 2+] and F[sup [minus

  18. Ytterbium- and neodymium-doped vanadate laser hose crystals having the apatite crystal structure

    DOEpatents

    Payne, Stephen A.; Kway, Wayne L.; DeLoach, Laura D.; Krupke, William F.; Chai, Bruce H. T.

    1994-01-01

    Yb.sup.3+ and Nd.sup.3+ doped Sr.sub.5 (VO.sub.4).sub.3 F crystals serve as useful infrared laser media that exhibit low thresholds of oscillation and high slope efficiencies, and can be grown with high optical quality. These laser media possess unusually high absorption and emission cross sections, which provide the crystals with the ability to generate greater gain for a given amount of pump power. Many related crystals such as Sr.sub.5 (VO.sub.4).sub.3 F crystals doped with other rare earths, transition metals, or actinides, as well as the many structural analogs of Sr.sub.5 (VO.sub.4).sub.3 F, where the Sr.sup.2+ and F.sup.- ions are replaced by related chemical species, have similar properties.

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

    PubMed

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

    2016-01-01

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

  20. Random lasers from dye-doped chiral photonic crystal films

    NASA Astrophysics Data System (ADS)

    Huang, Yuhua; Zhou, Ying; Wu, Shin-Tson

    2007-02-01

    We have obtained a dye-doped chiral photonic crystal (PC) film with reflection band gap much wider than its original band gap without dye dopants by using multiple-step fabrication processes. Moreover, the dye-doped chiral PC films using our multiple-step fabrication processes exhibit many oscillations within the broadened reflection band gap. The abrupt change of the optical density of state (DOS) around the oscillations provides the possibility of generating laser emission when the dye-doped chiral PC film is pumped by a pulsed laser with wavelength in the absorption region of the laser dye. Based on this property, we demonstrated random lasers which exhibit different multiple-mode laser wavelength at different spatial positions. Different from the random lasers induced by the scattering mechanism, the random lasers from the dye-doped cholesteric polymer film exhibit Gaussian-like beam shape and specific propagation orientation which is normal to the cholesteric planar surface. It is foreseeable that a high efficiency and high power broadband laser can be generated using cholesteric polymer films.

  1. Ultraviolet Laser-induced ignition of RDX single crystal

    PubMed Central

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

    2016-01-01

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

  2. Laser-Induced Thermal-Mechanical Damage Characteristics of Cleartran Multispectral Zinc Sulfide with Temperature-Dependent Properties

    NASA Astrophysics Data System (ADS)

    Peng, Yajing; Jiang, Yanxue; Yang, Yanqiang

    2015-01-01

    Laser-induced thermal-mechanical damage characteristics of window materials are the focus problems in laser weapon and anti-radiation reinforcement technology. Thermal-mechanical effects and damage characteristics are investigated for cleartran multispectral zinc sulfide (ZnS) thin film window materials irradiated by continuous laser using three-dimensional (3D) thermal-mechanical model. Some temperature-dependent parameters are introduced into the model. The temporal-spatial distributions of temperature and thermal stress are exhibited. The damage mechanism is analyzed. The influences of temperature effect of material parameters and laser intensity on the development of thermal stress and the damage characteristics are examined. The results show, the von Mises equivalent stress along the thickness direction is fluctuant, which originates from the transformation of principal stresses from compressive stress to tensile stress with the increase of depth from irradiated surface. The damage originates from the thermal stress but not the melting. The thermal stress is increased and the damage is accelerated by introducing the temperature effect of parameters or the increasing laser intensity.

  3. Crystal structure of laser-induced subsurface modifications in Si

    DOE PAGES

    Verburg, P. C.; Smillie, L. A.; Römer, G. R. B. E.; Haberl, B.; Bradby, J. E.; Williams, J. S.; Huis in ’t Veld, A. J.

    2015-06-04

    Laser-induced subsurface modification of dielectric materials is a well-known technology. Applications include the production of optical components and selective etching. In addition to dielectric materials, the subsurface modification technology can be applied to silicon, by employing near to mid-infrared radiation. An application of subsurface modifications in silicon is laser-induced subsurface separation, which is a method to separate wafers into individual dies. Other applications for which proofs of concept exist are the formation of waveguides and resistivity tuning. However, limited knowledge is available about the crystal structure of subsurface modifications in silicon. In this paper, we investigate the geometry and crystalmore » structure of laser-induced subsurface modifications in monocrystalline silicon wafers. Finally, in addition to the generation of lattice defects, we found that transformations to amorphous silicon and Si-iii/Si-xii occur as a result of the laser irradiation.« less

  4. Excimer laser crystallization of amorphous silicon on metallic substrate

    NASA Astrophysics Data System (ADS)

    Delachat, F.; Antoni, F.; Slaoui, A.; Cayron, C.; Ducros, C.; Lerat, J.-F.; Emeraud, T.; Negru, R.; Huet, K.; Reydet, P.-L.

    2013-06-01

    An attempt has been made to achieve the crystallization of silicon thin film on metallic foils by long pulse duration excimer laser processing. Amorphous silicon thin films (100 nm) were deposited by radiofrequency magnetron sputtering on a commercial metallic alloy (N42-FeNi made of 41 % of Ni) coated by a tantalum nitride (TaN) layer. The TaN coating acts as a barrier layer, preventing the diffusion of metallic impurities in the silicon thin film during the laser annealing. An energy density threshold of 0.3 J cm-2, necessary for surface melting and crystallization of the amorphous silicon, was predicted by a numerical simulation of laser-induced phase transitions and witnessed by Raman analysis. Beyond this fluence, the melt depth increases with the intensification of energy density. A complete crystallization of the layer is achieved for an energy density of 0.9 J cm-2. Scanning electron microscopy unveils the nanostructuring of the silicon after laser irradiation, while cross-sectional transmission electron microscopy reveals the crystallites' columnar growth.

  5. Optical, laser spectroscopic, and electrical characterization of transion metal doped zinc selenide and zinc sulfide nano-and-microcrystals

    NASA Astrophysics Data System (ADS)

    Kim, Changsu

    Middle-infrared lasers operating over a "molecular fingerprint" 2-15 mum spectral range are in great demand for a variety of applications. One of the best choices for lasing in the 2-5 mum spectral range is direct oscillation from divalent transition metal ions (TM2+: Cr 2+, Fe2+, Co2+)-doped wide bandgap II-VI semiconductor crystals. There are three major objectives in this dissertation: (1) Realize and study middle-infrared electroluminescence of n and p-type, Cr doped bulk ZnSe crystals. We have demonstrated a method of ZnSe crystals thermal-diffusion doping with donor (In, Zn, and Al) and acceptor (Cu, Ag, and N through CrN) impurities resulting in n and p-type conductivity of Cr:ZnSe. We are the first to our knowledge to obtain mid-IR electroluminescence in nominally p-type Cr:Ag:ZnSe, which could prove valuable for developing of novel mid-IR laser diodes. (2) En route to low dimensional gain material, develop simple method for making microscopic laser active Cr doped ZnSe, ZnS and CdSe powders, realize and study their laser spectroscopic characteristics. We have demonstrated a simple physical method of Cr2+:ZnSe, ZnS and CdSe powder fabrication with average sizes below ˜ 10mum and ˜1mum (eliminating stage of bulk crystal growth) and demonstrated first ever mid-IR random lasing on these powders under optical excitation. In addition, we have examine suspensions and polymer films impregnated with Cr:II-VI powders for random lasing in the mid-IR. The powder, suspension and polymer samples are fabricated and characterized through the measurement of photoluminescence (PL) spectra, PL kinetics, and lasing threshold energy. (3) En route to low dimensional gain material, develop method for making laser active Cr, Co, and Fe doped ZnSe and ZnS quantum dots (QD), realize and study their laser spectroscopic characteristics. We have demonstrated a novel method of TM doped II-VI QDs fabrication based on laser ablation in liquid and Ar environment. TM doped II-VI QDs

  6. Laser-diode pumped glass-clad Ti:sapphire crystal fiber laser.

    PubMed

    Wang, Shih-Chang; Hsu, Chun-Yang; Yang, Tzu-Te; Jheng, Dong-Yo; Yang, Teng-I; Ho, Tuan-Shu; Huang, Sheng-Lung

    2016-07-15

    Efficient glass-clad crystal fiber (CF) lasers were demonstrated using a Ti:sapphire crystalline core as the gain medium. With a core diameter of 18 μm, the laser diode (LD) pump source can be effectively coupled and guided throughout the crystal fiber for a low threshold and high slope efficiency laser operation. The advantage of high heat dissipation efficiency of the fiber structure can be derived from the low core temperature rising measurement (i.e., 17 K/W) with passive cooling. At an output transmittance of 23%, the lowest absorbed threshold of 118.2 mW and highest slope efficiency of 29.6% were achieved, with linear laser polarization.

  7. Laser-diode pumped glass-clad Ti:sapphire crystal fiber laser.

    PubMed

    Wang, Shih-Chang; Hsu, Chun-Yang; Yang, Tzu-Te; Jheng, Dong-Yo; Yang, Teng-I; Ho, Tuan-Shu; Huang, Sheng-Lung

    2016-07-15

    Efficient glass-clad crystal fiber (CF) lasers were demonstrated using a Ti:sapphire crystalline core as the gain medium. With a core diameter of 18 μm, the laser diode (LD) pump source can be effectively coupled and guided throughout the crystal fiber for a low threshold and high slope efficiency laser operation. The advantage of high heat dissipation efficiency of the fiber structure can be derived from the low core temperature rising measurement (i.e., 17 K/W) with passive cooling. At an output transmittance of 23%, the lowest absorbed threshold of 118.2 mW and highest slope efficiency of 29.6% were achieved, with linear laser polarization. PMID:27420499

  8. Synthesis of Mesostructured Copper Sulfide by Cation Exchange and Liquid Crystal Templating

    SciTech Connect

    Lubeck, C R; Doyle, F M; Gash, A E; Satcher, J H; Han, T Y

    2005-08-01

    describe for the first time, the successful synthesis of highly ordered, mesostructured Cu{sub x}S, by combining the templating of the supramolecular assemblies of non-ionic amphiphilic polymer method with the cation exchange method to transform mesostructured cadmium sulfide (CdS) into mesostructured copper sulfides (CuS, Cu{sub 2}S).

  9. Large mode-volume, large beta, photonic crystal laser resonator

    SciTech Connect

    Dezfouli, Mohsen Kamandar; Dignam, Marc M.

    2014-12-15

    We propose an optical resonator formed from the coupling of 13, L2 defects in a triangular-lattice photonic crystal slab. Using a tight-binding formalism, we optimized the coupled-defect cavity design to obtain a resonator with predicted single-mode operation, a mode volume five times that of an L2-cavity mode and a beta factor of 0.39. The results are confirmed using finite-difference time domain simulations. This resonator is very promising for use as a single mode photonic crystal vertical-cavity surface-emitting laser with high saturation output power compared to a laser consisting of one of the single-defect cavities.

  10. Czochralski growth and laser performance of alexandrite crystals

    SciTech Connect

    Guo, X.; Zhang, B.; Wu, L.; Chen, M.

    1986-08-15

    Alexandrite (BeAl/sub 2/O/sub 4/:Cr/sup 3 +/) crystals have been growing by the Czochralski technique and continually tunable laser output with energy of 304 mJ and slope efficiency of 0.46% in the wavelength range from 735 to 786 nm has been obtained using c-axis rods. Tunable Q-switch pulse output and LiIO/sub 3/ double-frequency have been also obtained.

  11. Laser-generated waves and wakes in rotating ion crystals.

    PubMed

    Kriesel, J M; Bollinger, J J; Mitchell, T B; King, L B; Dubin, D H E

    2002-03-25

    Locally excited plasma waves are generated in a Coulomb crystal by "pushing" with radiation pressure on a rotating cloud of laser-cooled 9Be+ ions. The waves form a stationary wake that is directly imaged through the dependence of the ion fluorescence on Doppler shifts, and theoretical calculations in a slab geometry are shown to accurately reproduce these images. The technique demonstrates a new method of exciting and studying waves in cold ion clouds.

  12. Smectic liquid crystal cell with heat pulse and laser

    SciTech Connect

    Mash, D.H.

    1984-10-16

    A method of operating a homeotropically aligned smectic liquid crystal cell in which the cell is turned from a clear to a scattering state by illumination with an intense flash of light after which a focused laser beam is scanned across the layer to leave clear tracks where homeotropic alignment has been restored thereby producing a display providing, in projection, bright lines on a dark background.

  13. Monitoring crystal dissolution at nanometer resolution using laser reflectometry

    NASA Astrophysics Data System (ADS)

    Eggington, P. J.; Taylor, A. G.

    2000-01-01

    Laser reflectometry has been used for the first time as an in situ real-time monitor of the dissolution of the (0 0 1) face of KClO 3 crystals into aqueous solution. During the dissolution process the reflected light was subject to constructive and destructive interference caused by the movement of crystal boundaries. This produced Fabry-Perot oscillations similar to the widely exploited phenomenon used in the laser reflectometry-based metrology of semiconductor surfaces. The method is adapted and theoretical fits to the observed data are presented. The quality of the data allows dissolution rates of 100 nm s -1 to be measured accurately. Data gained by this method was used to verify the concentration dependence of the dissolution rate and confirm it as a diffusion-controlled mechanism. The hydrodynamic radius of the diffusing ions was found to be 0.224 nm, in agreement with literature values. The potential of laser reflectometry for use as an effective probe sensitive to changes in crystal surface morphology during dissolution has also been demonstrated.

  14. Diffusion of Excitation in GGG:Yb3+ Laser Crystal

    NASA Astrophysics Data System (ADS)

    Kisialiou, I. G.; Ivakin, E. V.

    2015-01-01

    The excitation diffusion coefficient DE is measured directly in laser crystals by the optical method of high-frequency dynamic gratings. DE for Gd3Ga5O12:Yb3+ (21 at.%) crystal is found to be 3·10-9 cm3/s at room temperature and 1.2·10-8 cm3/s at 190°C. In KYW:Yb3+ (20 at.%) crystal no excitation diffusion is observed under the same experimental conditions. It is shown that DE is affected by the activator concentration, the temperature, and the probability of radiationless energy exchange between neighboring active impurity ions, which depends on the minimal distance between donor and acceptor.

  15. Crystal growth, polarized spectra, and laser performance of Yb:CaGdAlO4 crystal

    NASA Astrophysics Data System (ADS)

    Di, J. Q.; Xu, X. D.; Xia, C. T.; Zheng, L. H.; Aka, G.; Yu, H. H.; Sai, Q. L.; Guo, X. Y.; Zhu, L.

    2016-04-01

    In this paper, the crystal growth, polarized spectra, and laser performance of Yb:CaGdAlO4 crystal were reported. The segregation coefficient of Yb3+ ions was calculated to be 0.47. The cell parameters were determined to be a  =  b  =  0.3658 nm, c  =  1.1985 nm. The peak absorption cross-section was calculated to be 2.65  ×  10-20 cm2 at 979 nm and the peak stimulated emission cross-section was 2.23  ×  10-20 cm2 at 980 nm for the π polarization. The continuous-wave (CW) laser operations of uncoated Yb:CaGdAlO4 crystals with 5  ×  5  ×  3 mm3 in size were demonstrated. A maximum output power of 1.6 W at 1048 nm was obtained with a slope efficiency of 28%. The results show that Yb:CaGdAlO4 crystal is a promising laser medium.

  16. Multi-Colour Nanowire Photonic Crystal Laser Pixels

    PubMed Central

    Wright, Jeremy B.; Liu, Sheng; Wang, George T.; Li, Qiming; Benz, Alexander; Koleske, Daniel D.; Lu, Ping; Xu, Huiwen; Lester, Luke; Luk, Ting S.; Brener, Igal; Subramania, Ganapathi

    2013-01-01

    Emerging applications such as solid-state lighting and display technologies require micro-scale vertically emitting lasers with controllable distinct lasing wavelengths and broad wavelength tunability arranged in desired geometrical patterns to form “super-pixels”. Conventional edge-emitting lasers and current surface-emitting lasers that require abrupt changes in semiconductor bandgaps or cavity length are not a viable solution. Here, we successfully address these challenges by introducing a new paradigm that extends the laser tuning range additively by employing multiple monolithically grown gain sections each with a different emission centre wavelength. We demonstrate this using broad gain-bandwidth III-nitride multiple quantum well (MQW) heterostructures and a novel top-down nanowire photonic crystal nanofabrication. We obtain single-mode lasing in the blue-violet spectral region with a remarkable 60 nm of tuning (or 16% of the nominal centre wavelength) that is determined purely by the photonic crystal geometry. This approach can be extended to cover the entire visible spectrum. PMID:24135975

  17. Laser-induced modification of transparent crystals and glasses

    SciTech Connect

    Bulgakova, N M; Stoian, Razvan; Rosenfeld, A

    2010-12-29

    We analyse the processes taking place in transparent crystals and glasses irradiated by ultrashort laser pulses in the regimes typical of various applications in optoelectronics and photonics. We consider some phenomena, which have been previously described by the authors within the different model representations: charging of the dielectric surface due to electron photoemission resulting in a Coulomb explosion; crater shaping by using an adaptive control of the laser pulse shape; optimisation of the waveguide writing in materials strongly resistant to laser-induced compaction under ordinary irradiation conditions. The developed models and analysis of the processes relying on these models include the elements of the solid-state physics, plasma physics, thermodynamics, theory of elasticity and plasticity. Some important experimental observations which require explanations and adequate description are summarised. (photonics and nanotechnology)

  18. Sulfur incorporation into copper indium diselenide single crystals through annealing in hydrogen sulfide

    SciTech Connect

    Titus, Jochen; Birkmire, Robert W.; Hack, Christina; Mueller, Georg; McKeown, Patrick

    2006-02-15

    CuInSe{sub 2} crystals were sulfurized in a H{sub 2}S-Ar gas mixture at 575 deg. C. The focus was on the resulting mass transport, in particular, on the interdiffusion of Se and S. Experiments were done for various sulfurization times, and the resulting S distribution was measured by Auger electron spectroscopy sputter depth profiling and analyzed with the Boltzmann-Matano method. A one-dimensional diffusion process had shaped the S distribution in these crystals. The respective diffusion coefficient was on the order of 10{sup -16} cm{sup 2}/s, and it varied only slightly with the S content in CuIn(Se,S){sub 2}.

  19. Crystal and Magnetic Structures of the Oxide Sulfides CaCoSO and BaCoSO.

    PubMed

    Salter, Edward J T; Blandy, Jack N; Clarke, Simon J

    2016-02-15

    CaCoSO, synthesized from CaO, Co, and S at 900 °C, is isostructural with CaZnSO and CaFeSO. The structure is non-centrosymmetric by virtue of the arrangement of the vertex-sharing CoS3O tetrahedra which are linked by their sulfide vertices to form layers. The crystal structure adopts space group P63mc (No. 186), and the lattice parameters are a = 3.7524(9) Å and c = 11.138(3) Å at room temperature with two formula units in the unit cell. The compound is highly insulating, and powder neutron diffraction measurements reveal long-range antiferromagnetic order with a propagation vector k = (1/3, 1/3, 1/2). The magnetic scattering from a powder sample can be modeled starting from a 120° arrangement of Co(2+) spin vectors in the triangular planes and then applying a canting out of the planes which can be modeled in the magnetic space group C(c)c (space group 9.40 in the Belov, Neronova, and Smirnova (BNS) scheme) with Co(2+) moments of 2.72(5) μ(B). The antiferromagnetic structure of the recently reported compound BaCoSO, which has a very different crystal structure from CaCoSO, is also described, and this magnetic structure and the magnitude of the ordered moment (2.75(2) μ(B)) are found by experiment to be similar to those predicted computationally.

  20. Behavior of noble metals upon fractional crystallization of copper-rich sulfide melts

    NASA Astrophysics Data System (ADS)

    Distler, V. V.; Sinyakova, E. F.; Kosyakov, V. I.

    2016-08-01

    Joint behavior of Pt, Pd, Au, As, Bi, Te, and Sn upon fractional crystallization was studied in a melt of cubanite composition with the following admixtures (mol %): Fe, 33.20; Cu, 16.55; S, 50.03; Pt, 0.03; Pd, 0.02; Au, 0.02; As, 0.02; Bi, 0.03; Te, 0.02; Sn, 0.08. The crystallized sample consisted of three zones: (I) a pyrrhotite solid solution POSS; (II) an isocubanite ICB; (III) a multiphase mixture. The behavior of admixtures was studied in the first and second zones. It was shown that pyrrhotite did not contain admixtures of noble metals and accessory elements, whereas Sn was dissolved in cubanite. Other admixtures occurred in the second zone as multiphase inclusions. PdBi x Te1- x , PtBiS3-δ, CuPtBiS3, Bi2S3- x , Au, Pt(As,S)2, (Pt,Pd)S, (Pt,Pd)(Bi,Te)2- x , and PdBi2 were the most abundant phases.

  1. Gold in the Brunswick No. 12 volcanogenic massive sulfide deposit, Bathurst Mining Camp, Canada: Evidence from bulk ore analysis and laser ablation ICP-MS data on sulfide phases

    NASA Astrophysics Data System (ADS)

    McClenaghan, Sean H.; Lentz, David R.; Martin, Jillian; Diegor, Wilfredo G.

    2009-07-01

    The 329-Mt Brunswick No. 12 volcanogenic massive sulfide deposit (total resource of 163 Mt at 10.4% Zn, 4.2% Pb, 0.34% Cu, and 115 g/t Ag) is hosted within a Middle Ordovician bimodal volcanic and sedimentary sequence. Massive sulfides are for the most part syngenetic, and the bulk of the sulfide ore occurs as a Zn-Pb-rich banded sulfide facies that forms an intimate relationship with a laterally extensive Algoma-type iron formation and defines the Brunswick Horizon. Zone refining of stratiform sulfides is considered to have resulted in the development of a large replacement-style Cu-rich basal sulfide facies, which is generally confined between the banded sulfide facies and an underlying stringer sulfide zone. Complex polyphase deformation and associated lower- to upper-greenschist facies regional metamorphism is responsible for the present geometry of the deposit. Textural modification has resulted in a general increase in grain size through the development of pyrite and arsenopyrite porphyroblasts, which tend to overprint primary mineral assemblages. Despite the heterogeneous ductile deformation, primary features have locally been preserved, such as fine-grained colloform pyrite and base and precious metal zonation within the Main Zone. Base metal and trace element abundances in massive sulfides from the Brunswick No. 12 deposit indicate two distinct geochemical associations. The basal sulfide facies, characterized by a proximal high-temperature hydrothermal signature (Cu-Co-Bi-Se), contains generally low Au contents averaging 0.39 ppm ( n = 34). Conversely, Au is enriched in the banded sulfide facies, averaging 1.1 ppm Au ( n = 21), and is associated with an exhalative suite of elements (Zn-Pb-As-Sb-Ag-Sn). Finely laminated sulfide lenses hosted by iron formation at the north end of the Main Zone are further enriched in Au, averaging 1.7 ppm ( n = 41) and ranging up to 8.2 ppm. Laser ablation inductively coupled plasma-mass spectrometry (ICP-MS) analyses of

  2. Development of sulfide calibration standards for the laser ablation inductively-coupled plasma mass spectrometry technique

    USGS Publications Warehouse

    Wilson, S.A.; Ridley, W.I.; Koenig, A.E.

    2002-01-01

    The requirements of standard materials for LA-ICP-MS analysis have been difficult to meet for the determination of trace elements in sulfides. We describe a method for the production of synthetic sulfides by precipitation from solution. The method is detailed by the production of approximately 200 g of a material, PS-1, with a suite of chalcophilic trace elements in an Fe-Zn-Cu-S matrix. Preliminary composition data, together with an evaluation of the homogeneity for individual elements, suggests that this type of material meets the requirements for a sulfide calibration standard that allows for quantitative analysis. Contamination of the standard with Na suggests that H2S gas may prove a better sulfur source for future experiments. We recommend that calibration data be collected in whatever mode is closest to that employed for the analysis of the unknown material, because of variable fractionation effects as a function of analytical mode. For instance, if individual spot analyses are attempted on unknown sample, then a raster of several individual spot analyses, not a continuous scan, should be collected and averaged for the standard. Hg and Au are exceptions to the above and calibration data should always be collected in a scanning mode. Au is more heterogeneously distributed than other trace metals and large-area scans are required to provide an average value for calibration purposes. We emphasize that the values given in Table 1 are preliminary values. Further chemical characterization of this standard, through a round-robin analysis program, will allow the USGS to provide both certified and recommended values for individual elements. The USGS has developed PS-1 as a potential new LA-ICP-MS standard for use by the analytical community, and requests for this material should be addressed to S. Wilson. However, it is stressed that an important aspect of the method described here is the flexibility for individual investigators to produce sulfides with a wide range

  3. Modeling of Crystal Orientations in Laser Powder Deposition of Single Crystal Material

    NASA Astrophysics Data System (ADS)

    Qi, Huan; Liu, Zhaoyang

    This paper presents a numerical model which simulates the dynamic molten pool formation and the crystal orientations of solidified SX alloy in a multi-layer laser powder deposition process. Based on the mathematical model of coaxial laser direct deposition, the effect of parameters (laser power, scanning speed, powder feed rate) on the tendency to form [001] direction expitaxial grains during solidification was evaluated. In the transient three- dimensional model, physical phenomena including heat transfer, melting, grain formation during solidification, mass addition, and fluid flow in the melt pool, were modeled in a self-consistent manner. The temperature fields, fluid flow velocity, clad geometry (width, height and melt pool depth) and grain formation in melting pool of single layer are predicted.

  4. Increase of bulk optical damage threshold fluences of KDP crystals by laser irradiation and heat treatment

    DOEpatents

    Swain, J.E.; Stokowski, S.E.; Milam, D.; Kennedy, G.C.; Rainer, F.

    1982-07-07

    The bulk optical damage threshold fluence of potassium dihydrogen phosphate (KDP) crystals is increased by irradiating the crystals with laser pulses of duration 1 to 20 nanoseconds of increasing fluence, below the optical damage threshold fluence for untreated crystals, or by baking the crystals for times of the order of 24 hours at temperatures of 110 to 165/sup 0/C, or by a combination of laser irradiation and baking.

  5. Convex crystal x-ray spectrometer for laser plasma experiments

    SciTech Connect

    May, M.; Heeter, R.; Emig, J.

    2004-10-01

    Measuring time and space-resolved spectra is important for understanding Hohlraum and Halfraum plasmas. Experiments at the OMEGA laser have used the Nova TSPEC which was not optimized for the OMEGA diagnostic space envelope or for the needed spectroscopic coverage and resolution. An improved multipurpose spectrometer snout, the MSPEC, has been constructed and fielded on OMEGA. The MSPEC provides the maximal internal volume for mounting crystals without any beam interferences at either 2x or 3x magnification. The RAP crystal is in a convex mounting geometry bent to a 20 cm radius of curvature. The spectral resolution, E/dE, is about 200 at 2.5 keV. The spectral coverage is 2 to 4.5 keV. The MSPEC can record four separate spectra on the framing camera at time intervals of up to several ns. The spectrometer design and initial field-test performance will be presented and compared to that of the TSPEC.

  6. High Speed Crystal Growth by Q-switched Laser Melting

    NASA Technical Reports Server (NTRS)

    Cullis, A. G.

    1984-01-01

    The modification of the structural and electrical properties of semiconductors short radiation pulses obtained from Q-switched lasers is described. These modifications are accomplished by high heating and cooling rates. This processing revealed novel crystal growth and high speed resolidification phenomena. The behavior of semiconductor Si is analyzed. The annealing process typically employs short pulses of radiation in or near the visible region of the spectrum. The Q-switched ruby and Nd-YAG lasers are commonly used and these are sometimes mode locked to reduce the pulse length still further. Material to be annealed can be processed with a single large area radiation spot. Alternatively, a small radiation spot size can be used and a large sample area is covered by overlapping irradiated regions.

  7. Producing KDP and DKDP crystals for the NIF laser

    SciTech Connect

    Atherton, L J; Burnham, A K; Combs, R C; Couture, S A; De Yoreo, J J; Hawley-Fedder, R A; Montesant, R C; Robey, H F; Runkel, M; Staggs, M; Wegner, P J; Yan, M; Zaitseva, N P

    1999-09-02

    The cost and physics requirements of the NIF have established two important roles for potassium dihydrogen phosphate (KDP) crystals. 1. To extract more laser energy per unit of flashlamp light and laser glass, the NIF has adopted a multipass architecture as shown in Figure 1. Light is injected in the transport spatial filter, first traverses the power amplifiers, and then is directed to main amplifiers, where it makes four passes before being redirected through the power amplifiers towards the target. To enable the multipass of the main amplifiers, a KDP-containing Pockels cell rotates the polarization of the beam to make it either transmit through or reflect off a polarizer held at Brewster's angle within the main laser cavity. If transmitted, the light reflects off a mirror and makes another pass through the cavity. If reflected, it proceeds through the power amplifier to the target. the original seed crystal as the pyramid faces grow. Unfortunately, this pyramidal growth is very slow, and it takes about two years to grow a crystal to NIF size. To provide more programmatic flexibility and reduce costs in the long run, we have developed an alternative technology commonly called rapid growth. Through a combination of higher temperatures and higher supersaturation of the growth solution, a NIF-size boule can be grown in 1 to 2 months from a small ''point'' seed. However, growing boules of adequate size is not sufficient. Care must be taken to prevent inclusions of growth solution and incorporation of atomically substituted 2. Implosions for ICF work far better at shorter wavelengths due to less generation of hot electrons, which preheat the fuel and make it harder to compress. Compromising between optic lifetime and implosion efficiency, both Nova and the NIF operate at a tripled frequency of the 1053-nm fundamental frequency of a neodymium glass laser. This tripling is accomplished by two crystals, one made of KDP and one made of deuterated KDP (DKDP). The first

  8. One-dimensional parabolic-beam photonic crystal laser.

    PubMed

    Ahn, Byeong-Hyeon; Kang, Ju-Hyung; Kim, Myung-Ki; Song, Jung-Hwan; Min, Bumki; Kim, Ki-Soo; Lee, Yong-Hee

    2010-03-15

    We report one-dimensional (1-D) parabolic-beam photonic crystal (PhC) lasers in which the width of the PhC slab waveguide is parabolically tapered. A few high-Q resonant modes are confirmed in the vicinity of the tapered region where Gaussian-shaped photonic well is formed. These resonant modes originate from the dielectric PhC guided mode and overlap with the gain medium efficiently. It is also shown that the far-field radiation profile is closely associated with the symmetry of the structural perturbation.

  9. Surfactant-controlled composition and crystal structure of manganese(II) sulfide nanocrystals prepared by solvothermal synthesis

    PubMed Central

    Capetti, Elena; Ferretti, Anna M; Dal Santo, Vladimiro

    2015-01-01

    Summary We investigated how the outcome of the solvothermal synthesis of manganese(II) sulfide (MnS) nanocrystals (NCs) is affected by the type and amount of long chain surfactant present in the reaction mixture. Prompted by a previous observation that a larger than stoichiometric amount of sulfur is required [Puglisi, A.; Mondini, S.; Cenedese, S.; Ferretti, A. M.; Santo, N.; Ponti A. Chem. Mater. 2010, 22, 2804–2813], we carried out a wide set of reactions using Mn(II) carboxylates and Mn2(CO)10 as precursors with varying amounts of sulfur and carboxylic acid. MnS NCs were obtained provided that the S/Mn ratio was larger than the L/Mn ratio, otherwise MnO NCs were produced. Since MnS can crystallize in three distinct phases (rock salt α-MnS, zincblende β-MnS, and wurtzite γ-MnS), we also investigated whether the surfactant affected the NC polymorphism. We found that MnS polymorphism can be controlled by appropriate selection of the surfactant. γ-MnS nanocrystals formed when a 1:2 mixture of long chain carboxylic acid and amine was used, irrespective of the presence of carboxylic acid as a free surfactant or ligand in the metal precursor. When we used a single surfactant (carboxylic acid, alcohol, thiol, amine), α-MnS nanocrystals were obtained. The peculiar role of the amine seems to be related to its basicity. The nanocrystals were characterized by TEM and electron diffraction; ATR-FTIR spectroscopy provided information about the surfactants adsorbed on the NCs. PMID:26734522

  10. Solubility, thermal, photoconductivity and laser damage threshold studies on L-serine acetate (LSA) single crystal

    NASA Astrophysics Data System (ADS)

    Rajesh, K.; Thayanithi, V.; Mani, A.; Amudha, M.; Kumar, P. Praveen

    2015-06-01

    L-serine acetate crystal was grown by slow evaporation technique. Solubility of L-Serine Acetate was determined at different temperatures. L-Serine Acetate was characterized by SEM is to identify the morphology of the crystal. TG and DTA study reveals the thermal stability of the grown crystal. Dielectric measurement was carried out for different temperature ranges. Photo conductivity study revealed the nature of conductivity of the crystal under halogen light. Laser damage threshold of the crystal was measured using Nd:YAG laser source. NLO property of the crystal is confirmed by Kurtz-Perry powder technique.

  11. Ultrafast x-ray diffraction of laser-irradiated crystals

    NASA Astrophysics Data System (ADS)

    Heimann, P. A.; Larsson, J.; Chang, Z.; Lindenberg, A.; Schuck, P. J.; Judd, E.; Padmore, H. A.; Bucksbaum, P. H.; Lee, R. W.; Murnane, M.; Kapteyn, H.; Wark, J. S.; Falcone, R. W.

    1997-07-01

    An apparatus has been developed for measuring time-dependent x-ray diffraction. X-ray pulses from an Advanced Light Source bend magnet are diffracted by a sagittally-focusing Si (111) crystal and then by a sample crystal, presently InSb (111). Laser pulses with 100 fs duration and a repetition rate of 1 KHz irradiate the sample inducing a phase transition. Two types of detectors are being employed: an x-ray streak camera and an avalanche photodiode. The streak camera is driven by a photoconductive switch and has a 2 ps temporal resolution determined by trigger jitter. The avalanche photodiode has high quantum efficiency and sufficient time resolution to detect single x-ray pulses in ALS two bunch or `camshaft' operation. A beamline is under construction dedicated for time resolved and micro-diffraction experiments. In the new beamline a toroidal mirror collects 3 mrad horizontally and makes a 1:1 image of the bend magnet source in the x-ray hutch. A laser induced phase transition has been observed in InSb occurring within 70 ps.

  12. The Nokomis Cu-Ni-PGE Deposit, Duluth Complex: A sulfide-bearing, crystal-laden magmatic slurry

    NASA Astrophysics Data System (ADS)

    Peterson, D. M.

    2009-12-01

    deposit. A fundamental aspect of the ever-developing ore deposit model is an understanding of the initial conditions of the magmatic system - its crystallinity, sulfur capacity, geochemistry, and geometry - and how the sulfur saturated SKI magma lived, worked, and died. Such understanding includes the realization that the magma was a crystal-liquid (silicate and sulfide liquids) slurry and the identification of magma channelways and sub-channels and their associated thermal anomalies. In addition, the SKI magmas locally melted the footwall granitoid rocks, and such melts have been incorporated into the sulfide-bearing troctolitic melts of the SKI. In the end, hard work (>16,000 outcrops mapped, ~20,000 geochemical analyses completed, and >155,000 meters of core drilled) and intellectual geologic thought has been used to identify one of the world’s largest resources of Cu-Ni-PGEs.

  13. Photoinduced chemical reactions on natural single crystals and synthesized crystallites of mercury(II) sulfide in aqueous solution containing naturally occurring amino acids.

    PubMed

    Pal, Bonamali; Ikeda, Shigeru; Ohtani, Bunsho

    2003-03-10

    Photoirradiation at >300 nm of aqueous suspensions of several natural crystal specimens and synthesized crystallites of mercury(II) sulfide (HgS) induced deaminocyclization of optically active or racemic lysine into pipecolinic acid (PCA) under deaerated conditions. This is the first example, to the best of our knowledge, of photoinduced chemical reactions of natural biological compounds over natural minerals. It was found that the natural HgS crystals had activity higher than those of synthesized ones but lower than those of other sulfides of transition metals, e.g., CdS and ZnS, belonging to the same II-IV chalcogenides. In almost all of the photoreactions, decompostion of HgS occurred to liberate hydrogen sulfide (H(2)S) and Hg(2+), and the latter seemed to have undergone in-situ reductive deposition on HgS as Hg(0) after a certain induction period (24-70 h) during the photoirradiation, as indicated by the darkened color of the suspensions. The formation of PCA, presumably through combination of oxidation of lysine and reduction of an intermediate, cyclic Schiff base, could also be seen after a certain induction time of the Hg(0) formation. This was supported by the fact that the addition of small amount of Hg(2+) (0.5 wt % of HgS) increased the PCA yield by almost 2-fold. We also tried to elucidate certain aspects of the plausible stereochemical reactions in relation to the chiral crystal structure of HgS. Although, in some experiments, slight enantiomeric excess of the product PCA was observed, the excess was below or equal to the experimental error and no other supporting analytical data could not be obtained; we cannot conclude the enantiomeric photoproduction of PCA by the natural chiral HgS specimen. PMID:12611518

  14. A random laser made of nematic liquid crystal doped with a laser dye

    NASA Astrophysics Data System (ADS)

    Sznitko, L.; Kaliciak, K.; Adamow, A.; Mysliwiec, J.

    2016-06-01

    We report on random laser emission obtained in 5CB and E7 nematic liquid crystal (LC) mixtures doped with 1% weight to weight ratio of DCM laser dye. The LC cell was used as asymmetric planar waveguide were emission was collected from the edge of the sample. Variable stripe length method was utilized to estimate the gain and the losses coefficients. Both systems have shown the threshold energy fluence in order of several mJ/cm2. In both cases above Fredericks potential, significant increase of emission intensity was observed due to the increase of light scattering on liquid crystalline domains. Moreover the use of fifth order of diffraction grating covered with thin alumina film resulted in strong multimode and directional laser emission.

  15. Mid-IR Photonic-Crystal Interband Cascade Lasers

    NASA Astrophysics Data System (ADS)

    Kim, Mijin; Kim, Chul Soo; Bewley, William; Canedy, Chadwick; Lindle, James; Nolde, Jill; Larrabee, Diane; Vurgaftman, Igor; Meyer, Jerry

    2008-03-01

    Photonic-crystal distributed-feedback (PCDFB) semiconductor lasers have the potential to maintain optical coherence over very large areas. We report an electrically pumped PCDFB laser operating in a true single mode in the mid-infrared. A two-dimensional grating was formed on top of an interband cascade laser emitting at 3.3 μm by patterning a high-index Ge layer. The grating and the 400-μm-wide gain stripe were tilted by 20^o with respect to the facet. Current spreading was prevented by ion bombarding the region outside the gain stripe rather than etching of a ridge. The gain region at the back of the cavity was also terminated by ion bombardment, since feedback from the back facet is undesirable. A single mode was emitted with maximum cw output power > 60 mW, resolution-limited spectral linewidth (side-mode suppression ratio 27 dB), and single-lobe spatial far-field with angular full width at half maximum of 0.5^o. Comparison of the near and far field patterns indicated effective M^2 3. The observation of low efficiency is thought to be due primarily to inadequate grating coupling, which can be remedied by thickening the Ge layer.

  16. Study on the laser crystal thermal compensation of LD end-pumped Nd:YAG 1319 nm/1338 nm dual-wavelength laser

    NASA Astrophysics Data System (ADS)

    Sun, R.; Wu, C. T.; Yu, M.; Yu, K.; Wang, C.; Jin, G. Y.

    2015-12-01

    The thermal model of laser diode (LD) end-pumped Nd: YAG was established. We analyzed the thermal effect of the crystal during the generation of 1319 nm/1338 nm dual-wavelength laser. Together with the bonded and non-bonded Nd:YAG crystal characteristics, we proposed to consider the bonded crystal’s internal temperature distribution of the three axes abc for the first time. The results showed that, compared with the non-bonded crystals, the bonded crystals could effectively reduce the crystal temperature. It provided a theoretical basis to solve the problem related to the thermal effect of the laser crystal and improve the laser output performance. The Nd:YAG laser crystal thermal model in this article could be widely applicable to similar laser crystals. The results provide a method to analyze and evaluate bonding crystal thermal compensation effectiveness by establishing the Nd:YAG crystal’s temperature distribution.

  17. Packaging consideration of two-dimensional polymer-based photonic crystals for laser beam steering

    NASA Astrophysics Data System (ADS)

    Dou, Xinyuan; Chen, Xiaonan; Chen, Maggie Yihong; Wang, Alan Xiaolong; Jiang, Wei; Chen, Ray T.

    2009-02-01

    In this paper, we report the theoretical study of polymer-based photonic crystals for laser beam steering which is based on the superprism effect as well as the experiment fabrication of the two dimensional photonic crystals for the laser beam steering. Superprism effect, the principle for beam steering, was separately studied in details through EFC (Equifrequency Contour) analysis. Polymer based photonic crystals were fabricated through double exposure holographic interference method using SU8-2007. The experiment results were also reported.

  18. Effect of XeCl laser irradiation on the defect structure of Nd:YAG crystals

    NASA Astrophysics Data System (ADS)

    Panahibakhsh, S.; Jelvani, S.; Maleki, M. H.; Mollabashi, M.; Abolhosseini, S.

    2014-09-01

    This paper presents the effect of XeCl laser irradiation on Nd:YAG single crystal samples with various number of pulses at different repetition rates and laser fluences. Effects of the irradiation on the optical and structural properties of the crystal are analyzed by UV-vis-NIR spectroscopy. Annihilation of some point defects of the crystal structure is observed following laser irradiation at a fluence of 100 mJ cm-2 with 100 and 500 pulses. Increasing the laser fluence and pulse numbers leads to saturation and new defects are found to be formed in the crystal. Additional absorption spectra of the irradiated samples show that oxygen vacancies in the Nd:YAG crystals are removed during the low-dose irradiation. The laser irradiation is compared to the thermal annealing process for Nd:YAG crystal modification. Additional absorption spectrum of an annealed sample reveals that induced negative absorption band at 236 nm is correlated with the annihilation of the oxygen vacancy center. Our results also demonstrate that XeCl laser treatment has several advantages upon annealing at high temperatures in the Nd:YAG crystal quality improvement. Thus, the present work can give a new approach to modify Nd:YAG crystals to be used in a wide variety of solid-state laser engineering.

  19. Doping of germanium and silicon crystals with non-hydrogenic acceptors for far infrared lasers

    DOEpatents

    Haller, Eugene E.; Brundermann, Erik

    2000-01-01

    A method for doping semiconductors used for far infrared lasers with non-hydrogenic acceptors having binding energies larger than the energy of the laser photons. Doping of germanium or silicon crystals with beryllium, zinc or copper. A far infrared laser comprising germanium crystals doped with double or triple acceptor dopants permitting the doped laser to be tuned continuously from 1 to 4 terahertz and to operate in continuous mode. A method for operating semiconductor hole population inversion lasers with a closed cycle refrigerator.

  20. Mobility of Electron in DNA Crystals by Laser Radiation

    NASA Technical Reports Server (NTRS)

    Zhang, Kaixi; Zhao, Qingxun; Cui, Zhiyun; Zhang, Ping; Dong, Lifang

    1996-01-01

    The mobility of electrons in laser radiated DNA is closed to the energy transfer and energy migration of a biological molecule. Arrhenius has studied the conductivity of the electrons in a biological molecule. But his result is far from the experimental result and meanwhile the relation between some parameters in his theory and the micro-quantities in DNA is not very clear. In this paper, we propose a new phonon model of electron mobility in DNA and use Lippman-Schwinger equation and S-matrix theory to study the mobility of electrons in DNA crystal. The result is relatively close to the experiment result and some parameters in Arrhenius theory are explained in our work.

  1. Convex Crystal X-ray Spectrometer for Laser Plasma Experiments

    SciTech Connect

    May, M; Heeter, R; Emig, J

    2004-04-15

    Measuring time and space-resolved spectra is important for understanding Hohlraum and Halfraum plasmas. Experiments at the OMEGA laser have used the Nova TSPEC which was not optimized for the OMEGA diagnostic space envelope or for the needed spectroscopic coverage and resolution. An improved multipurpose spectrometer snout, the MSPEC, has been constructed and fielded on OMEGA. The MSPEC provides the maximal internal volume for mounting crystals without any beam interferences at either 2x or 3x magnification. The RAP crystal is in a convex mounting geometry bent to a 20 cm radius of curvature. The spectral resolution, E/dE, is about 200 at 2.5 keV. The spectral coverage is 2 to 4.5 keV. The MSPEC can record four separate spectra on the framing camera at time intervals of up to several ns. The spectrometer design and initial field-test performance will be presented and compared to that of the TSPEC. Work supported by U. S. DoE/UC LLNL contract W-7405-ENG-48

  2. Nonradiative relaxation in tunable solid state laser crystals

    NASA Technical Reports Server (NTRS)

    Gayen, S. K.; Wang, W. B.; Petricevic, V.; Alfano, R. R.

    1986-01-01

    The characteristics of nonradiative transitions between the 4T2 and 2E excited states of trivalent-chromium-ion-activated ruby (containing 0.04 percent Cr2O3 by weight) and alexandrite (containing 0.4 at. percent chromium ion) laser crystals were studied using the technique described by Gayen et al. (1985). In this technique, a 527-nm pulse excites the 4T2 band of the Cr(3+), and the subsequent population kinetics among excited states is monitored by an IR picosecond probe pulse as a function of pump-probe delay. In ruby, a resolution-limited sharp rise in the excited state population was followed by a long-lifetime decay, leading to an upper limit of 7 ps for the 4T2-state nonradiative lifetime. In alexandrite, a longer rise time was followed by a multicomponent decay. A theoretical model is proposed for explaining the induced absorption and the transition dynamics observed in these crystals.

  3. Laser initiated thermal tuning of a cholesteric liquid crystal

    SciTech Connect

    Natarajan, Lalgudi V.; Tondiglia, Vincent P.; Sutherland, Richard L.; Siwecki, Stephen A.; White, Timothy J.; Wofford, Jeremy M.; Bunning, Timothy J.

    2010-07-05

    We report on the large wavelength range and light-initiated thermal tuning of the reflection of a liquid crystal (LC) formulation (S811/ZLI-2806) near a smectic (SmA) to cholesteric (CLC) phase transition enabled by the use of a high order parameter heat transfer dye (anthraquinone, AQ). Upon irradiation with a 647 nm Krypton ion (Kr{sup +}) laser line, absorption by AQ generates heat that is transferred to the surrounding LC host. In the S811/ZLI-2806 formulation examined here, the optically generated increase in temperature serves to transition the phase from SmA to CLC. As has been documented, the SmA->CLC transition is typified by a pitch contraction that blueshifts the position of the CLC reflection, in this case a shift from 2500 to 700 nm that can occur in less than 100 s. The tuning range and speed are dependent on the laser power and the amount of dye in the cell.

  4. Nonradiative relaxation in tunable solid-state laser crystals

    SciTech Connect

    Gayen, S.K.; Wang, W.B.; Pettricevic, V.; Alfano, R.R.

    1985-12-01

    The picosecond excite-and-probe adsorption technique is used to study the nonradiative transition dynamics between the /sup 4/T/sub 2/ and the /sup 2/ E excited states of two trivalent-chromium-ion-activated laser crystals -- ruby and alexandrite. A 527-nm 7-ps pulse excites the /sup 4/T/sub 2/ pump band of the Cr/sup 3 +/ ion in these crystals, and the subsequent population kinetics among excited states is monitored by an infrared picosecond probe pulse as a function of pump-probe delay. In ruby, a resolution-limited sharp rise in the excited-state population followed by a long-lifetime decay is observed. This leads to an upper limit of 7 ps for the /sup 4/T/sub 2/ state nonradiative lifetime in ruby. In alexandrite, a longer risetime followed by a multicomponent decay is observed. A theoretical model is proposed for explaining the observed induced absorption and kinetics from excited states of the Cr/sup 3 +/ ion in these crystals. In alexandrite, vibrational relaxation rate for transition from the higher-lying vibrational states of /sup 4/T/sub 2/ to the bottom of /sup 4/T/sub 2/ energy parabola is estimated to be approx. 6 x 10/sup 10/ (relaxation time approx. 17 ps). Transition rate from the bottom of /sup 4/T/sub 2/ parabola to the /sup 2/E is found to be of the order of 3.7 x 10/sup 10//s (relaxation time approx. 27 ps), while the thermal refilling rate of /sup 4/T/sub 2/ from /sup 2/E is approx. 3.5 x 10/sup 9//s. The infrared absorption cross section from the excited /sup 4/T/sub 2/ state is estimated to about an order-of-magnitude higher than that from the metastable /sup 2/E level.

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

    NASA Astrophysics Data System (ADS)

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

    2013-05-01

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

  6. Design and fabrication of photonic crystal quantum cascade lasers for optofluidics.

    PubMed

    Loncar, Marko; Lee, Benjamin G; Diehl, Laurent; Belkin, Mikhail A; Capasso, Federico; Giovannini, Marcella; Faist, Jérôme; Gini, Emilio

    2007-04-16

    We present novel designs and demonstrate a fabrication platform for electrically driven lasers based on high quality-factor photonic crystal cavities realized in mid-infrared quantum cascade laser material. The structures are based on deep-etched ridges with their sides perforated with photonic crystal lattice, using focused ion beam milling. In this way, a photonic gap is opened for the emitted TM polarized light. Detailed modeling and optimization of the optical properties of the lasers are presented, and their application in optofluidics is investigated. Porous photonic crystal quantum cascade lasers have potential for on-chip, intracavity chemical and biological sensing in fluids using mid infrared spectroscopy. These lasers can also be frequency tuned over a large spectral range by introducing transparent liquid in the photonic crystal holes.

  7. Thermal effect of Nd:YVO4 crystal by laser diode end-pumped

    NASA Astrophysics Data System (ADS)

    Zheng, Yibo; Zhang, Lei; Jia, Liping; Kang, Junjian

    2008-12-01

    Based on Possion equation, a thermal conduct model of laser crystal was established. The temperature distribution in laser crystal were obtained,and the optics path difference(OPD) induced by end-face distortion and total OPD were caculated. Based on the calculation, the focal length of laser crystal with different pumping powers was obtained. The experimental result agrees with the caculated result very well. When the pumping power is 2 W and the radius of pumping beams is 320μm the OPD induced by end-face distortion is 36% of the toatal OPD for ND:YVO4 crystal. When the pumping power is 5W, the focal length of crystal is 29.7mm. The study shows that, for the solid-stste laser with high power, the OPD induced by end-face distortion has a large influence on theraml effect of laser crystal. This study provides a theoretical direction for improving the stability of laser and studying the thermal effect of laser crystal.

  8. Measurements of striae in CR+ doped YAG laser crystals

    NASA Technical Reports Server (NTRS)

    Cady, Fredrick M.

    1994-01-01

    Striations in Czochralski (CZ) grown crystals have been observed in materials such as GaAs, silicon, photorefractive crystals used for data storage, potassium titanyl phosphate crystals and LiNbO3. Several techniques have been used for investigating these defects including electron microscopy, laser scanning tomography, selective photoetching, X-ray diffuse scattering, interference orthoscopy, laser interferometry and micro-Fourier transform infrared spectroscopy mapping. A 2mm thick sample of the material to be investigated is illuminated with light that is absorbed and non-absorbed by the ion concentration to be observed. The back surface of the sample is focused onto a solid-state image detector and images of the input beam and absorbed (and diffracted) beams are captured at two wavelengths. The variation of the coefficient of absorption asa function of distance on the sample can be derived from these measurements. A Big Sky Software Beamcode system is used to capture and display images. Software has been written to convert the Beamcode data files to a format that can be imported into a spreadsheet program such as Quatro Pro. The spreadsheet is then used to manipulate and display data. A model of the intensity map of the striae collected by the imaging system has been proposed and a data analysis procedure derived. From this, the variability of the attenuation coefficient alpha can be generated. Preliminary results show that alpha may vary by a factor of four or five over distances of 100 mu m. Potential errors and problems have been discovered and additional experiments and improvements to the experimental setup are in progress and we must now show that the measurement techniques and data analysis procedures provide 'real' information. Striae are clearly visible at all wavelengths including white light. Their basic spatial frequency does not change radically, at least when changing from blue to green to white light. Further experimental and theoretical work can

  9. Laser processing and in-situ diagnostics for crystallization: from thin films to nanostructures

    NASA Astrophysics Data System (ADS)

    Yoo, Jae-Hyuck; In, Jung Bin; Zheng, Andy Cheng; Ryu, Sang-Gil; Hwang, David J.; Xiang, Bin; Minor, Andrew M.; Grigoropoulos, Costas P.

    2014-10-01

    Recent work on laser-induced crystallization of thin films and nanostructures is presented. Characterization of the morphology of the crystallized area reveals the optimum conditions for sequential lateral growth in a-Si thin films under high-pulsed laser irradiation. Silicon crystal grains of several micrometers in lateral dimensions can be obtained reproducibly. Laser-induced grain morphology change is observed in silicon nanopillars under a transmission electron microscopy (TEM) environment. The TEM is coupled with a near-field scanning optical microscopy (NSOM) pulsed laser processing system. This combination enables immediate scrutiny on the grain morphologies that the pulsed laser irradiation produces. The tip of the amorphous or polycrystalline silicon pillar is transformed into a single crystalline domain via melt-mediated crystallization. The microscopic observation provides a fundamental basis for laser-induced conversion of amorphous nanostructures into coarse-grained crystals. A laser beam shaping strategy is introduced to control the stochastic dewetting of ultrathin silicon film on a foreign substrate under thermal stimulation. Upon a single pulse irradiation of the shaped laser beam, the thermodynamically unstable ultrathin silicon film is dewetted from the glass substrate and transformed to a nanodome. The results suggest that the laser beam shaping strategy for the thermocapillary-induced de-wetting combined with the isotropic etching is a simple alternative for scalable manufacturing of array of nanostructures.

  10. EFFECTS OF LASER RADIATION ON MATTER. LASER PLASMA: Thermally induced optical damage to barium-sodium niobate crystals

    NASA Astrophysics Data System (ADS)

    Baryshev, S. A.; Goncharova, I. F.; Konvisar, P. G.; Kuznetsov, V. A.

    1990-06-01

    Thermally induced optical damage (TIOD) was observed in undoped barium-sodium niobate (BSN) crystals as a result of changes in their temperature. This damage was deduced from the behavior of YAG:Nd3+ laser radiation when a BSN crystal was inserted in the resonator and also using a helium-neon laser probe beam. The experimental results were satisfactorily explained by the familiar pyroelectric model of TIOD and, in the crystals studied, an inhomogeneity of the conductivity rather than an inhomogeneity of the pyroelectric constant played the main role.

  11. Laser demonstration of diode-laser-pumped Nd:Sr5(VO4)3F crystal

    NASA Astrophysics Data System (ADS)

    Zhao, Shengzhi; Wang, Qingpu; Zhang, Xingyu; Sun, Lianke; Zhang, Shaojun

    1996-03-01

    The absorption spectrum of a new crystal Nd:Sr6(VO4)3F, known as Nd:S-VAP, is measured and its strong absorption peak at 809 nm shows that it can be suitably pumped by laser-diode. By using a laser-diode pump operating at 809 nm, Nd:S-VAP crystal has been successfully lased at 1.065 micrometer. A highest slope efficiency of 43.5% and a lowest laser threshold of only 11 mW have been measured. The theoretical formulas for threshold power and slope efficiency were written, and the theoretical prediction is in agreement with the experimental result.

  12. Field method for sulfide determination

    SciTech Connect

    Wilson, B L; Schwarser, R R; Chukwuenye, C O

    1982-01-01

    A simple and rapid method was developed for determining the total sulfide concentration in water in the field. Direct measurements were made using a silver/sulfide ion selective electrode in conjunction with a double junction reference electrode connected to an Orion Model 407A/F Specific Ion Meter. The method also made use of a sulfide anti-oxidant buffer (SAOB II) which consists of ascorbic acid, sodium hydroxide, and disodium EDTA. Preweighed sodium sulfide crystals were sealed in air tight plastic volumetric flasks which were used in standardization process in the field. Field standards were prepared by adding SAOB II to the flask containing the sulfide crystals and diluting it to the mark with deionized deaerated water. Serial dilutions of the standards were used to prepare standards of lower concentrations. Concentrations as low as 6 ppB were obtained on lake samples with a reproducibility better than +- 10%.

  13. New Yb-doped crystals for high-power and ultrashort lasers

    NASA Astrophysics Data System (ADS)

    Druon, F.; Boudeile, J.; Zaouter, Y.; Hanna, M.; Balembois, F.; Georges, P.; Petit, J.; Goldner, P.; Viana, B.

    2006-09-01

    Since the beginning of the 90's, Titanium Sapphire has become the crystal of choice for the development of ultrashort laser system producing very short and powerful pulses using the Chirped Pulse Amplification technique. In parallel to these developments leading to commercial products, new laser crystals have been studied in order to reach directly other wavelength range and to overcome the need to develop cw or pulsed green laser to pump the Titanium Sapphire crystal. In order to be able to directly pump the crystals with very efficient and high power semiconductor laser, new crystals doped with ytterbium ions have been developed. Actually, in the field of femtosecond lasers, an intense interest has been shown for ytterbium-doped laser-crystals. These crystals are now well-known to be particularly suitable for very efficient, directly-diode-pumped, solid state femtosecond oscillators. However, it has been shown that the spectral properties of the Yb 3+ dopant strongly depend on the matrix host and a lot of works have been done to find the "ideal" matrix allowing both ultrashort-pulsed and high-power lasers. Firstly, in order to take advantage of the very high-power laser diodes available to pump Yb-doped materials, ideal crystals need to be able to hold high power pumping; so high thermal conductivity is required (>5W/m/K, typically). Secondly, to generate very short pulses (<100 fs) ideal crystals have to demonstrate very broad and smooth spectra. Among the numerous Yb-doped crystals already studied, many failed with one of these two contradictory criteria (contradictory because broad spectra are often synonymous of high disorder in the host lattice and the good thermal conductivity requires an ordered matrix to allow good propagation of phonons). In this paper, we are relating the performance of a new Yb-doped crystal: Yb:CaGdAlO4 (Yb:CALGO) and how it takes place in this quest of "ideal" crystal. Actually, this very new crystal allowed, to our best knowledge

  14. One-step photoinscription of asymmetrically oriented fresnoite-type crystals in glass by ultrafast laser.

    PubMed

    He, Xuan; Poumellec, Bertrand; Liu, Qiming; Brisset, Francois; Lancry, Matthieu

    2014-09-15

    Oriented fresnoite-type crystals (Sr(2)TiSi(2)O(8)) were photoinduced directly in bulk silica-based glass by femtosecond laser irradiation at high repetition rate (typ. 300 kHz). Unlike related results obtained from other researchers, asymmetrical polar-axis orientation of those nonlinear crystals in transverse direction of the cross section has been demonstrated by electron backscattered diffraction and micro-second-harmonic generation (SHG). The nonlinear optical property of laser lines has been further characterized by SHG measurement. We found that the preferential directions of the polar axis were in the laser motion direction with a small dispersion in part of the heated volume. The other part of the crystallized volume shows an axis perpendicular to the writing direction. The mechanism of asymmetric orientation of femtosecond-laser-induced crystallization also is discussed. PMID:26466288

  15. Spectroscopy and laser performance of Nd:Lu_2O_3 crystal

    NASA Astrophysics Data System (ADS)

    Hao, Liangzhen; Wu, Kui; Cong, Hengjiang; Yu, Haohai; Zhang, Huaijin; Wang, Zhengping; Wang, Jiyang

    2011-08-01

    The spectra of Nd3+:Lu2O3 crystal have been examined at room temperature. Judd-Ofelt theory was applied to calculate the spectral parameters of the crystal. With a laser diode as pump source, a continuous-wave laser output power of 2.81 W is achieved, which is the highest value ever reported in this crystals to our knowledge, and its wavelength is also found to be dual-wavelength. Because of the emission cross-section at 1076 nm and 1080 nm are almost identical, laser oscillation for such two wavelengths can be obtained simultaneously. All the properties show that Nd:Lu2O3 is an excellent crystal for laser applications.

  16. Nematic polymer liquid-crystal wave plate for high-power lasers at 1054 nm

    SciTech Connect

    Kreuzer, F. ); Korenic, E.M.; Jacobs, S.D.; Houghton, J.K.; Schmid, A. )

    1994-04-01

    A nematic polymer liquid crystal is used to construct wave plates for use at 1054 nm. Three methods of wave-plate construction are discussed: double substrate with fiber spacers in homogeneous distribution, double substrate with fiber spacers in annular distribution, and single substrate. The polymer liquid crystal shows high laser-damage resistance, making it particularly useful for high-peak-power laser applications. Alignment techniques and measurement of birefringence for the highly viscous polymer are described.

  17. Chemical insights into the synthesis and properties of polycrystalline and single crystal iron scandium sulfide (FeSc2S4)

    NASA Astrophysics Data System (ADS)

    Morey, Jennifer R.; Plumb, Kemp W.; Koohpayeh, Seyed M.; Broholm, Collin L.; McQueen, Tyrel M.

    Iron scandium sulfide, FeSc2S4, has recently attracted significant theoretical and experimental interest as a candidate spin-orbital liquid. An AB2X4 spinel, FeSc2S4 (space group Fd-3m, No. 227) features a high degree of frustration associated with the Fe2+, which occupies the A-site diamond sublattice and is tetrahedrally coordinated by sulfur. The Fe2+ ion is in a high spin (S =2) state, resulting in orbital degeneracy due to a single hole on the e orbitals. We report the strides we have made to produce material in powder and single crystal form, and the relationship between the chemistry and the structural, magnetic, and thermodynamic properties of FeSc2S4. This work was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Material Sciences and Engineering, under Grant No. DEFG02-08ER46544.

  18. The pushing gate in a planar Coulomb crystal using a flat-top laser beam

    NASA Astrophysics Data System (ADS)

    Kitaoka, M.; Buluta, I. M.; Hasegawa, S.

    2009-08-01

    We propose a pushing gate for entangling two ions in a planar Coulomb crystal in the view of realizing large-scale quantum simulations. A tightly focused laser is irradiated from the direction perpendicular to the crystal plane and its spatial intensity profile generates a state-dependent force. We analyze the error sources in this scheme and obtain low infidelity.

  19. Investigation on improvement of laser quality of tunable Al2O3:Ti3+ crystals

    NASA Astrophysics Data System (ADS)

    Deng, Peizhen; Chai, Yao; Yan, Shenghui; Zhang, Guanming; Sun, Yang; Gan, Fuxi

    1990-11-01

    The process of growing large diameter and lower residual infrared absorption single crystals of Al203:T13+ by a new growth technique named induction field up- shift method (IFSM) is described, and some of the problems in producing high laser quality single crystal are discussed using different techniques have been given.

  20. Investigation on growth and laser properties of GGG:(Nd,Cr) single crystals

    SciTech Connect

    Zhang; Lin; Liu; Liu; Zhu

    1986-04-04

    Investigation on the growth and laser properties of gadolinium gallium garnet crystal doped with neodymium and chromium is reported. As the segregation coefficient of Nd in GGG is less than 1 and that of Cr is greater than 1, a modified Czochralski method for growth is adopted in order to keep the dopants being uniform in the grown crystal.

  1. Laser quality single crystal specimens. Final report, 27 September-30 November 1980

    SciTech Connect

    Pollak, T.

    1980-12-15

    Research and development on the crystalline laser host, YLF (LiYF4), was completed during this program. The study involved crystal growth and sample fabrication of rare earth doped YLF. These materials were then evaluated at NRL. A total of 16 laser samples, eight different compositions, were processed during this contract period.

  2. Photonic crystal surface-emitting lasers enabled by an accidental Dirac point

    SciTech Connect

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

    2014-12-02

    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.

  3. Holographic recording in a doubly doped lithium niobate crystal with two wavelengths: a blue laser diode and a green laser

    NASA Astrophysics Data System (ADS)

    Komori, Yuichi; Ishii, Yukihiro

    2010-08-01

    A doubly-doped LiNbO3 (LN) crystal has been well used as a nonvolatile two-wavelength recording material. By using two levels of the crystal, two-kind holograms can be recorded on one crystal; a hologram is recorded with a 405-nm blue laser diode (LD) for a deep Mn level, and another hologram is with a 532-nm green laser for a shallow Fe level. The recording capacity doubles. A 780-nm LD is non-volatile reconstructing source since the LD line is insensitive to both levels. Multiplexed reconstructed images are demonstrated by using a sharp angular selectivity of a volume LN crystal keeping Bragg condition with spherical reconstructions.

  4. A multi-dimensional investigation of laser conditioning in KDP and DKDP crystals

    SciTech Connect

    DeMange, P; Negres, R A; Carr, C W; Radousky, H B; Demos, S G

    2005-10-31

    We present a multi-parametric experimental investigation of laser conditioning efficiency and behavior in KDP and DKDP crystals as a function of laser wavelength, fluence, number of pulses, and conditioning protocol. Our results expose complex behaviors associated with damage initiation and conditioning at different wavelengths that provide a major step towards revealing the underlying physics. In addition, we reveal the key parameters for optimal improvement to the damage performance from laser conditioning.

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

    SciTech Connect

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

    2013-12-31

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

  6. Catastrophic nanosecond laser induced damage in the bulk of potassium titanyl phosphate crystals

    SciTech Connect

    Wagner, Frank R. Natoli, Jean-Yves; Akhouayri, Hassan; Commandré, Mireille; Duchateau, Guillaume

    2014-06-28

    Due to its high effective nonlinearity and the possibility to produce periodically poled crystals, potassium titanyl phosphate (KTiOPO{sub 4}, KTP) is still one of the economically important nonlinear optical materials. In this overview article, we present a large study on catastrophic nanosecond laser induced damage in this material and the very similar RbTiOPO{sub 4} (RTP). Several different systematic studies are included: multiple pulse laser damage, multi-wavelength laser damage in KTP, damage resistance anisotropy, and variations of the laser damage thresholds for RTP crystals of different qualities. All measurements were carried out in comparable experimental conditions using a 1064 nm Q-switched laser and some were repeated at 532 nm. After summarizing the experimental results, we detail the proposed model for laser damage in this material and discuss the experimental results in this context. According to the model, nanosecond laser damage is caused by light-induced generation of transient laser-damage precursors which subsequently provide free electrons that are heated by the same nanosecond pulse. We also present a stimulated Raman scattering measurement and confront slightly different models to the experimental data. Finally, the physical nature of the transient damage precursors is discussed and similarities and differences to laser damage in other crystals are pointed out.

  7. Ridge waveguide lasers in Nd:GGG crystals produced by swift carbon ion irradiation and femtosecond laser ablation.

    PubMed

    Jia, Yuechen; Dong, Ningning; Chen, Feng; Vázquez de Aldana, Javier R; Akhmadaliev, Sh; Zhou, Shengqiang

    2012-04-23

    We report on the fabrication of ridge waveguide in Nd:GGG crystal by using swift C(5+) ion irradiation and femtosecond laser ablation. At room temperature continuous wave laser oscillation at wavelength of ~1063 nm has been realized through the optical pump at 808 nm with a slope efficiency of 41.8% and the pump threshold is 71.6 mW.

  8. Cantilever-enhanced photoacoustic detection of hydrogen sulfide (H2S) using NIR telecom laser sources near 1.6 µm

    NASA Astrophysics Data System (ADS)

    Moser, H.; Lendl, B.

    2016-04-01

    Sensitive detection of hydrogen sulfide (H2S) at different pressure levels using a cantilever-enhanced photoacoustic detector in combination with a telecom NIR L-band laser source is reported. Amplitude and wavelength modulation schemes for photoacoustic signal generation are compared. A detection limit (3 σ) of 8 ppmv was achieved for amplitude modulation mode with a 50-s averaging time for the H2S absorption near 1.6 µm. As compared to simulated spectra, the cantilever-enhanced photoacoustic detection approach in combination with the sufficiently stable and narrow bandwidth NIR laser is able to reproduce the rotationally resolved H2S spectrum at low pressures of 300 mbar.

  9. Mid-infrared photothermal heterodyne spectroscopy in a liquid crystal using a quantum cascade laser

    PubMed Central

    Mërtiri, Alket; Jeys, Thomas; Liberman, Vladimir; Hong, M. K.; Mertz, Jerome; Altug, Hatice; Erramilli, Shyamsunder

    2012-01-01

    We report a technique to measure the mid-infrared photothermal response induced by a tunable quantum cascade laser in the neat liquid crystal 4-octyl-4′-cyanobiphenyl (8CB), without any intercalated dye. Heterodyne detection using a Ti:sapphire laser of the response in the solid, smectic, nematic and isotropic liquid crystal phases allows direct detection of a weak mid-infrared normal mode absorption using an inexpensive photodetector. At high pump power in the nematic phase, we observe an interesting peak splitting in the photothermal response. Tunable lasers that can access still stronger modes will facilitate photothermal heterodyne mid-infrared vibrational spectroscopy. PMID:22912508

  10. Optical bistability in erbium-doped yttrium aluminum garnet crystal combined with a laser diode.

    PubMed

    Maeda, Y

    1994-01-10

    Optical bistability was observed in a simple structure of an injection laser diode combined with an erbium-doped yttrium aluminum garnet crystal. Since a hysteresis characteristic exists in the relationship between the wavelength and the injection current of a laser diode, an optical memory function capable of holding the output status is confirmed. In addition, an optical signal inversion was caused by the decrease of transmission of the erbium-doped yttrium aluminum garnet crystal against the red shift (principally mode hopping) of the laser diode. It is suggested that the switching time of this phenomenon is the time necessary for a mode hopping by current injection.

  11. Effect of crystal axis in temperature dependence of laser-induced damage thresholds by nanosecond near-infrared laser

    NASA Astrophysics Data System (ADS)

    Mikami, Katsuhiro; Sugita, Tsuyoshi; Azumi, Minako; Jitsuno, Takahisa

    2015-10-01

    Laser-induced damage thresholds in crystalline quartz were evaluated using a single-mode Nd:YAG laser (wavelength 1064 nm, pulse width 4 ns) at temperatures ranging from 123 K to 473 K. In this experiment, three kinds of crystalline quartz different in the cut direction were prepared. The damage morphologies were coincident with the crystal structure. The laser induced damage thresholds in crystalline quartz differed according to the cutting direction. The laser-induced damage thresholds expect in the case of Z-cut sample increased with decreasing temperature. The cutting direction of the Z-cut of crystalline quartz was parallel to the crystal axis. A tendency of the temperature dependence was the same with in the case of the glass materials. In contrast, the laser-induced damage threshold of the Z-cut sample decreased with decreasing temperature. The difference in the temperature-dependent behaviors of crystalline quartz is explained using physical models. The crystal axis influenced strongly to the electron resistivity and the electron avalanche process in laser-induced damage mechanisms was affected in the result.

  12. Crystallization of amorphous titanium oxide thin films by pulsed UV-laser irradiation

    SciTech Connect

    Ichikawa, Yo; Adachi, Hideaki; Setsune, Kentaro; Kawashima, Syunichiro; Kugimiya, Koichi

    1996-12-31

    Oxide ceramic materials are applied to many electric devices using dielectric, ferroelectric, piezoelectric and elastic properties. Effects of ultraviolet (UV) laser irradiation on the local crystal structure have been investigated for amorphous Ti-O thin films sputtered on ST-cut quartz substrates. The irradiation was conducted with a pulsed KrF excimer laser of 248 nm in wavelength. There were few changes in the optical transmission spectra of the films before and after the irradiation. The crystal structure of the films was characterized by electron diffraction, XPS and EXAFS analyses. The results obtained from these analyses suggest the films gradually crystallize to a TiO{sub 2} crystal with the rutile type structure by the increasing of the laser pulses.

  13. Far-field detection system for laser beam and crystal alignment

    NASA Astrophysics Data System (ADS)

    Zhang, Jiachen; Liu, Daizhong; Zhu, Baoqiang; Tang, Shunxing; Gao, Yanqi

    2016-03-01

    Laser beam far-field alignment as well as frequency-doubling and frequency-tripling crystal adjustment is very important for high-power laser facility. Separate systems for beam and crystal alignment are generally used while the proposed approach by off-axial grating sampling share common optics for these two functions, reducing both space and cost requirements. This detection system has been demonstrated on the National Laser Facility of Israel. The experimental results indicate that the average far-field alignment error is <5% of the spatial filter pinhole diameter, average autocollimation angle error of crystals is <10 μrad, and average frequency-tripling conversion efficiency is 69.3%, which meet the alignment system requirements on the beam direction and crystals.

  14. Ytterbium-Doped Yettrium Aluminum Garnet Crystal Fiber Multipass Ring Laser

    NASA Astrophysics Data System (ADS)

    Yi, Jui-Yun; Huang, Kuang-Yao; Lai, Chien-Chih; Peng, Hsin; Chen, Li-Hsuan; Huang, Sheng-Lung

    2010-12-01

    We report the growth of ytterbium-doped yettrium aluminum garnet (Yb:YAG) crystal fibers by the laser-heated pedestal growth (LHPG) method. The characteristics of Yb:YAG crystal fibers were analyzed by electron probe microanalyzer (EPMA) and X-ray diffraction measurements. The small crystal fiber diameter makes it effective for heat removal from a high-Yb3+-concentration and quasi-three-level gain medium. The length of this crystal-fiber-based high absorption can be shorter, which is eminently suitable for a multipass ring cavity to maintain cavity stability and mode symmetry. We successfully demonstrated a two-mirror multipass ring laser with 54.7% slope efficiency, which is higher than the 50.3% for a bulk Yb:YAG laser.

  15. Effect of surface morphology on laser-induced crystallization of amorphous silicon thin films

    NASA Astrophysics Data System (ADS)

    Huang, Lu; Jin, Jing; Wang, Guohua; Shi, Weimin; Yang, Weiguang; Yuan, Zhijun; Cao, Zechun; Zhou, Jun; Lou, Qihong; Liu, Jin; Wei, Guangpu

    2013-12-01

    The effect of surface morphology on laser-induced crystallization of hydrogenated intrinsic amorphous silicon (a-Si:H) thin films deposited by PECVD is studied in this paper. The thin films are irritated by a frequency-doubled (λ=532 nm) Nd:YAG pulsed nanosecond laser. An effective melting model is built to identify the variation of melting regime influenced by laser crystallization. Based on the experimental results, the established correlation between the grain growth characterized by AFM and the crystalline fraction (Xc) obtained from Raman spectroscopy suggests that the crystallized process form amorphous phase to polycrystalline phase. Therefore, the highest crystalline fraction (Xc) is obtained by a optimized laser energy density.

  16. Space-selective growth of frequency-conversion crystals in glasses with ultrashort infrared laser pulses.

    PubMed

    Miura, K; Qiu, J; Mitsuyu, T; Hirao, K

    2000-03-15

    We report on space-selective growth of a second-harmonic-generation beta-BaB(2)O(4) (BBO) crystal inside a BaO-Al(2)O(3)-B(2)O(3) glass sample at the focal point of an 800-nm femtosecond laser beam. A spherical heated region was formed during the focused laser irradiation through observation with an optical microscope. We moved the heated region by changing the position of the focal point of the laser beam relative to the glass sample. We grew BBO crystal continuously in the glass sample by adjusting the moving speed of the heated zone. Our results demonstrate that functional crystals can be formed three dimensionally in glasses by use of a nonresonant ultrashort pulsed laser.

  17. Mode-hop-free photonic crystal laser fabricated by holographic exposure technology.

    PubMed

    Zhang, Can; Wang, Baojun; Liang, Song; Zhu, Hongliang; Wang, Wei

    2014-05-15

    A mode-hop-free single-mode laser with a two-dimensional photonic crystal was demonstrated. In the device, the photonic crystal was realized by double holographic exposure technology. This novel procedure simplifies the fabrication of such structures greatly. The design of a reverse junction in the photonic crystal layer induces a partial gain coupling into the laser, which could break the symmetry of the transmission spectrum and realize stable single-mode lasing of the laser. The fabricated device has a high single-mode stability and side-mode suppression ratio of over 45 dB without mode hop at a relatively wide injected current range. The measurement results indicate that the laser with a simple fabrication process is promising as a stable single-mode and high-power light source in optical communication systems.

  18. Selenium Sulfide

    MedlinePlus

    Selenium sulfide comes in a lotion and is usually applied as a shampoo. As a shampoo, selenium sulfide usually is used twice a week for the first ... it is irritating. Rinse off all of the lotion.Do not use this medication on children younger ...

  19. Yb 3+-doped oxide crystals for diode-pumped solid state lasers: crystal growth, optical spectroscopy, new criteria of evaluation and combinatorial approach

    NASA Astrophysics Data System (ADS)

    Boulon, G.

    2003-04-01

    Our recent scientific program has involved the general evaluation of Yb 3+-doped oxide crystals for diode-pumped solid state lasers. Among crystalline families which provide the best expected performances, some have been grown: sesquioxide, oxyapatite, niobate and garnet fibres pulled either from the Laser Heated Pedestal Growth (LHPG) or the Micro-Pulling Down ( μ-PD) technique, tungstates by the top nucleated floating crystal (TNFC) and garnet and oxiapatite by the Czochralski (CZ) technique. Optical spectra of all crystals have been performed. In addition, a combinatorial chemistry approach has been pointed out to study the radiative lifetime and the concentration quenching processes in these laser crystals.

  20. Laser radiation frequency doubling in a single-crystal fibre based on a stoichiometric LiNbO{sub 3} crystal

    SciTech Connect

    Kashin, V V; Nikolaev, D A; Rusanov, S Ya; Tsvetkov, V B

    2015-01-31

    We demonstrate the employment of single-crystal optical fibres based on lithium niobate for doubling the laser radiation frequency. The measured characteristics of the fibre confirm its high quality and spatial homogeneity. Parameters of the frequency doublers for neodymium laser radiation (λ = 1 mm) based on fibre and bulk single crystals are compared. Single crystals are grown by the method of laser-heated pedestal growing with heating by radiation of a CO{sub 2} laser (LHPG-method). (nonlinear optical phenomena)

  1. [Study on Spectral Characteristics of Two Kinds of Home-Made Novel Yb-Doped Fluoride Laser Crystals].

    PubMed

    Xu, Wen-bin; Chai, Lu; Shi, Jun-kai; Song, You-jian; Hu, Ming-lie; Wang, Qing-yue; Su, Liang-bi; Jiang, Da-peng; Xu, Jun

    2015-09-01

    Yb-doped fluoride crystals are of important another Yb-doped laser materials besides Yb-doped oxide, which are becoming one of interests for developing tunable lasers and ultrafast lasers. In this paper, the systematic and contrastive experiments of the optical spectral characteristics are presented for two types of home-made novel Yb-doped fluoride laser crystals, namely, Yb-doped CaF2-SrF2 mixed crystal and co-doped Yb, Y:CaF2 single crystal. The fluorescent features of Yb-doped CaF2-SrF2 mixed crystal and co-doped Yb, Y:CaF2 single crystal are apparently different by the fluorescence experiment. The physical mechanism of these fluorescence spectra were analyzed and proposed. The influence of doping concentrations of active Yb(3+) ions or co-doping Y ions on the absorption of Yb-doped CaF2-SrF2 mixed crystal and co-doped Yb, Y:CaF2 single crystal was experimentally investigated, and the optimal values of doping concentrations of active Yb(3+) ions or co-doping Y ions in the two types of fluoride laser crystals were obtained. Continuous-wave laser operation for the two novel fluoride laser crystals has been achieved in three-mirror-folded resonator using a laser diode as the pump source. Therein, the laser operation for the co-doped Yb, Y:CaF2 crystal is demonstrated for the first time. For the two types of fluoride laser crystals (four samples), the input-output power relational curves, the optical slope efficiencies and the laser spectra were demonstrated by the laser experiments. By comparisons between the two types of fluoride laser crystals in the absorbability, fluorescence and laser spectra, laser threshold and slope efficiency of the continuous-wave laser operation, the results show that the best one of the four samples in spectral and laser characteristics is co-doped 3at%Yb, 6at% Y:CaF2 single crystal, which has an expected potential in the application. The research results provide available references for improving further laser performance of Yb

  2. Two-dimensional photonic crystal bandedge laser with hybrid perovskite thin film for optical gain

    NASA Astrophysics Data System (ADS)

    Cha, Hyungrae; Bae, Seunghwan; Lee, Myungjae; Jeon, Heonsu

    2016-05-01

    We report optically pumped room temperature single mode laser that contains a thin film of hybrid perovskite, an emerging photonic material, as gain medium. Two-dimensional square lattice photonic crystal (PhC) backbone structure enables single mode laser operation via a photonic bandedge mode, while a thin film of methyl-ammonium lead iodide (CH3NH3PbI3) spin-coated atop provides optical gain for lasing. Two kinds of bandedge modes, Γ and M, are employed, and both devices laser in single mode at similar laser thresholds of ˜200 μJ/cm2 in pulse energy density. Polarization dependence measurements reveal a clear difference between the two kinds of bandedge lasers: isotropic for the Γ-point laser and highly anisotropic for the M-point laser. These observations are consistent with expected modal properties, confirming that the lasing actions indeed originate from the corresponding PhC bandedge modes.

  3. Contamination and Radiation Effects on Nonlinear Crystals for Space Laser Systems

    NASA Technical Reports Server (NTRS)

    Abdeldayem, Hossain A.; Dowdye, Edward; Jamison, Tracee; Canham, John; Jaeger, Todd

    2005-01-01

    Space Lasers are vital tools for NASA s space missions and military applications. Although, lasers are highly reliable on the ground, several past space laser missions proved to be short-lived and unreliable. In this communication, we are shedding more light on the contamination and radiation issues, which are the most common causes for optical damages and laser failures in space. At first, we will present results based on the study of liquids and subsequently correlate these results to the particulates of the laser system environment. We present a model explaining how the laser beam traps contaminants against the optical surfaces and cause optical damages and the role of gravity in the process. We also report the results of the second harmonic generation efficiency for nonlinear optical crystals irradiated with high-energy beams of protons. In addition, we are proposing to employ the technique of adsorption to minimize the presence of adsorbing molecules present in the laser compartment.

  4. Dual-wavelength waveguide lasers at 1064 and 1079 nm in Nd:YAP crystal by direct femtosecond laser writing.

    PubMed

    Nie, Weijie; Cheng, Chen; Jia, Yuechen; Romero, Carolina; Vázquez de Aldana, Javier R; Chen, Feng

    2015-05-15

    Low-loss depressed cladding waveguides have been produced in Nd:YAP laser crystal by using direct femtosecond laser writing. Under optical pump at 812 nm at room temperature, continuous-wave simultaneous dual-wavelength laser oscillations at 1064 and 1079 nm, both along TM polarization, have been realized in the waveguiding structures. It has been found that, with the variation of pump polarization, the intensity ratio of 1064 and 1079 nm emissions varies periodically, while the polarization of output dual-wavelength laser remains unchanged. The maximum output power achieved for the Nd:YAP waveguide lasers is ∼200  mW with a slope efficiency of 33.4%.

  5. Structural and electronic characterization of 355 nm laser-crystallized silicon: Interplay of film thickness and laser fluence

    SciTech Connect

    Semler, Matthew R.; Swenson, Orven F.; Hoey, Justin M.; Guruvenket, Srinivasan; Gette, Cody R.; Hobbie, Erik K.

    2014-04-28

    We present a detailed study of the laser crystallization of amorphous silicon thin films as a function of laser fluence and film thickness. Silicon films grown through plasma-enhanced chemical vapor deposition were subjected to a Q-switched, diode-pumped solid-state laser operating at 355 nm. The crystallinity, morphology, and optical and electronic properties of the films are characterized through transmission and reflectance spectroscopy, resistivity measurements, Raman spectroscopy, X-ray diffraction, atomic force microscopy, and optical and scanning-electron microscopy. Our results reveal a unique surface morphology that strongly couples to the electronic characteristics of the films, with a minimum laser fluence at which the film properties are optimized. A simple scaling model is used to relate film morphology to conductivity in the laser-processed films.

  6. Observation of lattice defects in orthorhombic hen-egg white lysozyme crystals with laser scattering tomography

    NASA Astrophysics Data System (ADS)

    Sato, K.; Fukuba, Y.; Mitsuda, T.; Hirai, K.; Moriya, K.

    1992-08-01

    The effectivity of using laser scattering tomography (LST) as a nondestructive technique for finding lattice defects in protein crystals is demonstrated using an orthorhombic egg-white lysozyme crystal grown by a batch method. It was found that LST figures could be observed from the crystal portions where no defects were detectable by the naked eye or optical microscopy; the number of microdefects revealed in the LST patterns increased on approaching the crystal surface. Two types of defects were differentiated by polarization analysis: (1) point-type defects, assumed to be microdefects such as vacancies, precipitates, or impurities, and (2) bulk-type defects, assumed to correspond to inclusions.

  7. Growth Of Large-Diameter Crystals By Hem Tmfor Optical And Laser Applications

    NASA Astrophysics Data System (ADS)

    Khattak, C. P.; Schmid, F.

    1984-12-01

    The Heat Exchanger Method (HEM), a new crystal growth process, is in commercial production for 20 cm diameter sapphire crystals and 40 cm diameter silicon ingots for optical applications. The simplicity of the HEM combined with a very high degree of control of the submerged, solid-liquid interface allows growth of high-quality crystals. The HEM is also being adapted for the growth of Co:MgF2, Ti:A1203 and Cr:A1203 crystals for laser applications.

  8. Heterogeneously integrated photonic-crystal lasers on silicon for on/off chip optical interconnects.

    PubMed

    Takeda, Koji; Sato, Tomonari; Fujii, Takuro; Kuramochi, Eiichi; Notomi, Masaya; Hasebe, Koichi; Kakitsuka, Takaaki; Matsuo, Shinji

    2015-01-26

    We demonstrate the continuous-wave operation of lambda-scale embedded active-region photonic-crystal (LEAP) lasers at room temperature, which we fabricated on a Si wafer. The on-Si LEAP lasers exhibit a threshold current of 31 μA, which is the lowest reported value for any type of semiconductor laser on Si. This reveals the great potential of LEAP lasers as light sources for on- or off-chip optical interconnects with ultra-low power consumption in future information communication technology devices including CMOS processors.

  9. High-energy picosecond hybrid fiber/crystal laser for thin films solar cells micromachining

    NASA Astrophysics Data System (ADS)

    Lecourt, Jean-Bernard; Boivinet, Simon; Bertrand, Anthony; Lekime, Didier; Hernandez, Yves

    2015-05-01

    We report on an hybrid fiber/crystal ultra-short pulsed laser delivering high pulse energy and high peak power in the picosecond regime. The laser is composed of a mode-lock fiber oscillator, a pulse picker and subsequent fiber amplifiers. The last stage of the laser is a single pass Nd:YVO4 solid-state amplifier. We believe that this combination of both technologies is a very promising approach for making efficient, compact and low cost lasers compatible with industrial requirements.

  10. Substrate temperature effects on laser crystallized NiTi thin films

    SciTech Connect

    Birnbaum, A. J.; Yao, Y. L.; Chung, Ui-Jin; Im, James S.; Huang, X.; Ramirez, A. G.

    2009-04-01

    Amorphous sputter-deposited NiTi thin films were subjected to pulsed, melt-mediated laser crystallization techniques to engineer their microstructure. The effects of laser processing of preheated films are examined. Laser processing of films at an elevated substrate temperature has a significant effect on the rate with which solidification occurs. It is observed that the preheating temperature at which processing is carried out has significant implications for the resulting phase and microstructure, and therefore mechanical properties. Furthermore, the microstructural effects of varying incident laser energy density are examined via atomic force microscopy, scanning electron microscopy, and x-ray diffraction, and mechanical/shape memory properties are characterized via nanoindentation.

  11. A novel laser-based method for controlled crystallization in dental prosthesis materials

    NASA Astrophysics Data System (ADS)

    Cam, Peter; Neuenschwander, Beat; Schwaller, Patrick; Köhli, Benjamin; Lüscher, Beat; Senn, Florian; Kounga, Alain; Appert, Christoph

    2015-02-01

    Glass-ceramic materials are increasingly becoming the material of choice in the field of dental prosthetics, as they can feature both high strength and very good aesthetics. It is believed that their color, microstructure and mechanical properties can be tuned such as to achieve an optimal lifelike performance. In order to reach that ultimate perfection a controlled arrangement of amorphous and crystalline phases in the material is required. A phase transformation from amorphous to crystalline is achieved by a heat treatment at defined temperature levels. The traditional approach is to perform the heat treatment in a furnace. This, however, only allows a homogeneous degree of crystallization over the whole volume of the parent glass material. Here a novel approach using a local heat treatment by laser irradiation is presented. To investigate the potential of this approach the crystallization process of SiO2-Li2O-Al2O3-based glass has been studied with laser systems (pulsed and continuous wave) operating at different wavelengths. Our results show the feasibility of gradual and partial crystallization of the base material using continuous laser irradiation. A dental prosthesis machined from an amorphous glassy state can be effectively treated with laser irradiation and crystallized within a confined region of a few millimeters starting from the body surface. Very good aesthetics have been achieved. Preliminary investigation with pulsed nanosecond lasers of a few hundreds nanoseconds pulse width has enabled more refinement of crystallization and possibility to place start of phase change within the material bulk.

  12. Far-field detection system for laser beams alignment and crystals alignment

    NASA Astrophysics Data System (ADS)

    Liu, D.; Qin, H.; Zhu, B.

    2015-08-01

    Laser beams far-field alignment is very important for the high power laser facility as well as the frequency doubling crystals adjustment. Traditional beams alignment system and crystals alignment system are separated. That means, they use different optical image systems and CCD cameras, which will occupy larger space and use more money. A new farfield detection system of laser beams is presented with a big diffraction grating (37mm*37mm), a set of optical imaging components and a high resolution CCD camera. This detection system, which is fully demonstrated on the National Laser Facility of Israel, can align high power laser facility beams' direction as well as the frequency doubling crystals. The new system occupies small space in the spatial filter through off-axial grating sampling. The experimental results indicate that the average far-field alignment error is less than 5% of spatial filter pinhole diameter, and the average crystals' matching angle error is less than 10urad, which meet the alignment system requirements for beams and crystals.

  13. Influence of surface cracks on laser-induced damage resistance of brittle KH₂PO₄ crystal.

    PubMed

    Cheng, Jian; Chen, Mingjun; Liao, Wei; Wang, Haijun; Wang, Jinghe; Xiao, Yong; Li, Mingquan

    2014-11-17

    Single point diamond turning (SPDT) currently is the leading finishing method for achieving ultra-smooth surface on brittle KH(2)PO(4) crystal. In this work, the light intensification modulated by surface cracks introduced by SPDT cutting is numerically simulated using finite-difference time-domain algorithm. The results indicate that the light intensification caused by surface cracks is wavelength, crack geometry and position dependent. Under the irradiation of 355 nm laser, lateral cracks on front surfaces and conical cracks on both front and rear surfaces can produce light intensification as high as hundreds of times, which is sufficient to trigger avalanche ionization and finally lower the laser damage resistance of crystal components. Furthermore, we experimentally tested the laser-induced damage thresholds (LIDTs) on both crack-free and flawed crystal surfaces. The results imply that brittle fracture with a series of surface cracks is the dominant source of laser damage initiation in crystal components. Due to the negative effect of surface cracks, the LIDT on KDP crystal surface could be sharply reduced from 7.85J/cm(2) to 2.33J/cm(2) (355 nm, 6.4 ns). In addition, the experiment of laser-induced damage growth is performed and the damage growth behavior agrees well with the simulation results of light intensification caused by surface cracks with increasing crack depths.

  14. Thermal characterization, crystal field analysis and in-band pumped laser performance of Er doped NaY(WO(4))(2) disordered laser crystals.

    PubMed

    Serrano, María Dolores; Cascales, Concepción; Han, Xiumei; Zaldo, Carlos; Jezowski, Andrzej; Stachowiak, Piotr; Ter-Gabrielyan, Nikolay; Fromzel, Viktor; Dubinskii, Mark

    2013-01-01

    Undoped and Er-doped NaY(WO4)2 disordered single crystals have been grown by the Czochralski technique. The specific heat and thermal conductivity (κ) of these crystals have been characterized from T = 4 K to 700 K and 360 K, respectively. It is shown that κ exhibits anisotropy characteristic of single crystals as well as a κ(T) behavior observed in glasses, with a saturation mean free phonon path of 3.6 Å and 4.5 Å for propagation along a and c crystal axes, respectively. The relative energy positions and irreducible representations of Stark Er(3+) levels up to (4)G(7/2) multiplet have been determined by the combination of experimental low (<10 K) temperature optical absorption and photoluminescence measurements and simulations with a single-electron Hamiltonian including both free-ion and crystal field interactions. Absorption, emission and gain cross sections of the (4)I(13/2)↔(4)I(15/2) laser related transition have been determined at 77 K. The (4)I(13/2) Er(3+) lifetime (τ) was measured in the temperature range of 77-300 K, and was found to change from τ (77K) ≈ 4.5 ms to τ (300K) ≈ 3.5 ms. Laser operation is demonstrated at 77 K and 300 K by resonantly pumping the (4)I(13/2) multiplet at λ≈1500 nm with a broadband (FWHM≈20 nm) diode laser source perfectly matching the 77 K crystal (4)I(15/2) → (4)I(13/2) absorption profile. At 77 K as much as 5.5 W of output power were obtained in π-polarized configuration with a slope efficiency versus absorbed pump power of 57%, the free running laser wavelength in air was λ≈1611 nm with the laser output bandwidth of 3.5 nm. The laser emission was tunable over 30.7 nm, from 1590.7 nm to 1621.4 nm, for the same π-polarized configuration.

  15. Nonlinear optical frequency conversion with KTP and BiBO crystals for lasers in space

    NASA Astrophysics Data System (ADS)

    Potreck, Arne; Schröder, Helmut; Lammers, Melanie; Tzeremes, Georgios; Riede, Wolfgang

    2014-09-01

    Within ESA's ADM-Aeolus and EarthCARE missions Doppler-wind Lidar systems will be operated in the Earth's orbit to measure global wind profiles. The active instrument will be based on a Nd:YAG laser, frequency tripled by nonlinear optical crystals. Different crystals are therefore to compare and qualify in regard of their space acceptability. A dedicated set-up to measure the maximum conversion efficiencies and its stability during longterm operation for KTP crystals (SHG) and BiBO crystals (SHG and THG) is presented in this work. In order to detect gray-tracking and its influence on thermal lensing in situ, measurements with a Shack-Hartmann sensor and a co-aligned HeNe laser were performed. Conversion efficiencies were 76+/-3 % at SHG for KTP and BiBO crystals and 48+/-2 % at THG with a combination of two BiBO crystals. During longterm experiments of 60 million laser pulses, conversion efficiencies were demonstrated to be stable over time (+/-1 % at SHG with KTP and +/-2 % at THG with BiBO). The occurrence of gray-tracking was detected in the KTP crystal and the resulting thermal lensing with an exponential saturation over time was observed in situ.

  16. Transient stress evolution and crystallization in laser-irradiated amorphous titania sol-gel films

    SciTech Connect

    Exarhos, G.J.; Hess, N.J.; Wood, S.

    1991-10-01

    Amorphous TiO{sub 2} sol-gel films are irreversibly transformed to a crystalline anatase phase when heated to temperatures in excess of 575 K or subjected to intense pulsed or CW laser irradiation. The laser-induced transformation is initiated as a result of impurity absorption and subsequent heating, and results in densification and relative changes in compressive stress of the film. Isothermally annealed films exhibit a decrease in compressive stress as crystallization proceeds while an increase in compressive stress followed by a decrease in stress is observed when crystallization is laser-induced. Raman spectroscopy has been used to characterize the crystallization ingrowth kinetics and is used in this work as a real time probe of both film temperature and localized stress which can be evaluated from shifts in lattice phonon frequencies measured in real time during laser irradiation. The laser not only induces the phase transformation but excites inelastic Raman scattering from which film stress and temperature can be estimated. A second approach for the determination of these parameters requires incorporation of a thin ruby film between the titania and silica substrate. Here, the wavelength shift of the laser-induced ruby fluorescence can be used to quantify interfacial stress; the fluorescence lifetime measurements are used to determine temperature. The advantages and limitations of these techniques for evaluating transient stress and temperature evolution in thin titania films subjected to CW laser irradiation will be discussed.

  17. Generation and use of high power 213 nm and 266 nm laser radiation and tunable 210-400 nm laser radiation with BBO crystal matrix array

    DOEpatents

    Gruen, Dieter M.

    2000-01-01

    A 213 nm laser beam is capable of single photon ablative photodecomposition for the removal of a polymer or biological material substrate. Breaking the molecular bonds and displacing the molecules away from the substrate in a very short time period results in most of the laser photon energy being carried away by the displaced molecules, thus minimizing thermal damage to the substrate. The incident laser beam may be unfocussed and is preferably produced by quintupling the 1064 nm radiation from a Nd:YAG solid state laser, i.e., at 213 nm. In one application, the 213 nm laser beam is expanded in cross section and directed through a plurality of small beta barium borate (BBO) crystals for increasing the energy per photon of the laser radiation directed onto the substrate. The BBO crystals are arranged in a crystal matrix array to provide a large laser beam transmission area capable of accommodating high energy laser radiation without damaging the BBO crystals. The BBO crystal matrix array may also be used with 266 nm laser radiation for carrying out single or multi photon ablative photodecomposition. The BBO crystal matrix array may also be used in an optical parametric oscillator mode to generate high power tunable laser radiation in the range of 210-400 nm.

  18. Growth, spectral properties, and laser demonstration of Nd:GYSO crystal

    NASA Astrophysics Data System (ADS)

    Li, D. Z.; Xu, X. D.; Cong, Z. H.; Zhang, J.; Tang, D. Y.; Zhou, D. H.; Xia, C. T.; Wu, F.; Xu, J.

    2011-07-01

    An Nd:GYSO crystal has been grown by the Czochralski technique. The cell parameters were analyzed with X-ray diffraction (XRD). Room-temperature absorption and fluorescence spectra and fluorescence lifetime of the Nd:GYSO crystal were measured and analyzed. The Judd-Ofelt intensity parameters Ω 2,4,6 were obtained to be 4.06, 4.65, and 3.63×10-20 cm2, respectively. The absorption and emission cross sections and the branching ratios were calculated. The peak-emission cross section is 3.8×10-20 cm2 at 1074 nm with a FWHM of 8.8 nm. Pumped by a laser diode, a maximum 1.54 W continuous-wave (CW) laser output has been obtained with a slope efficiency of 27.4%. All the results show that Nd:GYSO crystal is a promising laser material.

  19. Induced crystallization in CW laser-irradiated sol-gel deposited titania films

    SciTech Connect

    Exarhos, G.J.; Hess, N.J.

    1993-12-31

    Isothermal annealing of amorphous TiO{sub 2} films deposited from acidic sol-gel precursor solutions results in film densification and concomitant increase in refractive index. Subsequent heating above 300C leads to irreversible transformation to an anatase crystalline phase. Similar phenomena occur when such amorphous films are subjected to focused cw laser irradiation. Controlled variations in laser fluence are used to densify or crystallize selected regions of the film. Low fluence conditioning leads to the evolution of a subtle nanograin-size morphology, evident in AFM images, which appears to retard subsequent film crystallization when such regions are subjected to higher laser fluence. Time-resolved Raman spectroscopy has been used to characterize irradiated regions in order to follow the crystallization kinetics, assess phase homogeneity, and evaluate accompanying changes in residual film stress.

  20. Laser-Heated Floating Zone Production of Single-Crystal Fibers

    NASA Technical Reports Server (NTRS)

    Ritzert, Frank; Westfall, Leonard

    1996-01-01

    This report describes how a laser-heated floating zone apparatus can be used to investigate single-crystal fibers of various compositions. A feedrod with a stoichiometric composition of high-purity powders was connected to a pedestal and fed into a laser scan where it combined with a single-crystal fiber seed. A molten zone was formed at this junction. As the feedrod was continuously fed into the laser scan, a single-crystal fiber of a prescribed orientation was withdrawn from the melt. The resultant fibers, whose diameters ranged from 100 to 250 gm, could then be evaluated on the basis of their growth behavior, physical properties, mechanical properties, and fiber perfection.

  1. Quantitative correlation between facets defects of RDX crystals and their laser sensitivity.

    PubMed

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

    2016-08-01

    In this work, the {210} facets of cyclotrimethylenetrinitramine (RDX) single crystals with different quality were studied by scanning electron microscopy and atomic force microscopy. Their laser sensitivity was then assessed using a direct laser ignition test irradiated with ultraviolet laser (wavelength: 355nm, pulse width: 6.4ns). Quantitative relationships between laser sensitivity and surface defects of RDX (210) and (2¯1¯0) facets were investigated. It is determined that the laser sensitivity exhibits significant correlation with the surface roughness, size of which is comparable with scales of laser wavelength. 3D FDTD simulations disclose that this relationship can be well explained with light intensity modulation effects induced by micro-defects on the initial plane wave. PMID:27054669

  2. High-power narrow-vertical-divergence photonic band crystal laser diodes with optimized epitaxial structure

    SciTech Connect

    Liu, Lei; Qu, Hongwei; Liu, Yun; Zhang, Yejin; Zheng, Wanhua; Wang, Yufei; Qi, Aiyi

    2014-12-08

    900 nm longitudinal photonic band crystal (PBC) laser diodes with optimized epitaxial structure are fabricated. With a same calculated fundamental-mode divergence, stronger mode discrimination is achieved by a quasi-periodic index modulation in the PBC waveguide than a periodic one. Experiments show that the introduction of over 5.5 μm-thick PBC waveguide contributes to only 10% increment of the internal loss for the laser diodes. For broad area PBC lasers, output powers of 5.75 W under continuous wave test and over 10 W under quasi-continuous wave test are reported. The vertical divergence angles are 10.5° at full width at half maximum and 21.3° with 95% power content, in conformity with the simulated angles. Such device shows a prospect for high-power narrow-vertical-divergence laser emission from single diode laser and laser bar.

  3. Syntheses, crystal structures, and NLO properties of the quaternary sulfides RE{sub 3}Sb{sub 0.33}SiS{sub 7} (RE=La, Pr)

    SciTech Connect

    Zhao, Hua-Jun

    2015-07-15

    Two quaternary sulfides RE{sub 3}Sb{sub 0.33}SiS{sub 7} (RE=La, Pr) have been prepared from stoichiometric mixtures of elements at 1223 K in an evacuated silica tube. They are the first examples of chalcogenides in the quaternary RE/Si/Sb/Q (RE=rare earth metal; Q=S, Se, Te) system. These two isostructural materials crystallize in the Ce{sub 3}Al{sub 1.67}S{sub 7} structure type in the hexagonal space group P6{sub 3}. Their structure features one-dimensional chains of face-sharing SbS{sub 6} octahedra running parallel to the c direction surrounded by the discrete SiS{sub 4} tetrahedra and RE cations. The La{sub 3}Sb{sub 0.33}SiS{sub 7} exhibits a SHG signal about 0.5 times that of the commercially used IR NLO material AgGaS{sub 2} at 2.05 μm laser. The optical gap of 1.92 eV for La{sub 3}Sb{sub 0.33}SiS{sub 7} was deduced from UV/Vis reflectance spectroscopy. - Graphical abstract: The RE{sub 3}Sb{sub 0.33}SiS{sub 7} (RE=La, Pr), crystalling in the Ce{sub 3}Al{sub 1.67}S{sub 7} structure type, have been prepared. The La{sub 3}Sb{sub 0.33}SiS{sub 7} exhibits a SHG signal about 0.5 times that of the IR NLO material AgGaS{sub 2}. - Highlights: • The RE{sub 3}Sb{sub 0.33}SiS{sub 7} (RE=La, Pr), crystalling in the Ce{sub 3}Al{sub 1.67}S{sub 7} structure type, have been prepared. • The La{sub 3}Sb{sub 0.33}SiS{sub 7} exhibits a SHG signal about 0.5 times that of the IR NLO material AgGaS{sub 2}. • The optical gap of 1.92 eV for La{sub 3}Sb{sub 0.33}SiS{sub 7} was deduced from UV/Vis reflectance spectroscopy.

  4. Analysis of birefringence effects in laser crystals by full vectorial beam propagation method

    NASA Astrophysics Data System (ADS)

    Hartmann, Rainer; Pflaum, Christoph; Graupeter, Thomas

    2014-05-01

    Modern laser technology demands powerful numerical tools to predict the efficiency of laser configurations. Birefringence has a strong influence on the beam quality and output power of a laser amplifier. We developed a complex physical model for simulating laser amplifiers and analyzing the birefringence effects. This model includes pump configuration, thermal lensing effects, birefringence, and beam propagation in the laser amplifier. The pump configuration is simulated using a complete three-dimensional ray tracing or by an approximation based on super-Gaussian functions. For an accurate modeling of the thermal lensing effect, the deformation of the end faces and the polarization dependent index of refraction was taken into account. Temperature, deformation and stress inside the laser crystal were calculated by a three-dimensional finite element analysis (FEA). In particular, the refractive index was accurately calculated by considering its temperature dependency and the photo elastic effect. This refractive index was used in the simulation of laser beam propagation through an amplifier. These simulations were performed by a complete three-dimensional vectorial beam propagation method (VBPM). The advantage of VBPM is that it can be applied to a polarization dependent index of refraction. This is important when taking into account the birefringence obtained by the photo elastic effect inside the laser crystal. The beam propagation method is based on finite elements on block structured grids as well as a Crank-Nicolson approximation in the propagation direction (FE-BPM). Reflecting boundaries were eliminated by introducing a perfect matching layer (PML). Simulation results show that a complete three-dimensional simulation model was useful in analyzing and optimizing high power laser amplifiers. The value of our model lies in the fact that it can take into account the crystal cut direction. Based on this the birefringence for simulating the laser beam quality and

  5. Large-aperture YCOB crystal growth for frequency conversion in the high average power laser system

    NASA Astrophysics Data System (ADS)

    Fei, Yiting; Chai, Bruce H. T.; Ebbers, C. A.; Liao, Z. M.; Schaffers, K. I.; Thelin, P.

    2006-04-01

    Yttrium calcium oxyborate YCa4O(BO3)3 (YCOB) is a novel non-linear optical crystal possessing good thermal, mechanical and non-linear optical properties. Large-aperture YCOB crystals with 75 mm diameter were grown for high-average power frequency conversion on the mercury laser system. The growth morphology (included facet and spiral growth), cracking and inclusions in the as-grown crystal boule were discussed as the critical problem for large-aperture YCOB crystal growth. This can be minimized through modification of the growth program, including pulling rate, separation procedure, and cooling program. High-average power frequency conversion of the mercury laser using YCOB has been demonstrated, and experimental validation of YCOB material yields 50% conversion at 10 Hz has been achieved.

  6. Progress in the Growth of Yb:S-FAP Laser Crystals

    SciTech Connect

    Schaffers, K I; Tassano, J B; Waide, P A; Payne, S A; Morris, R C

    2000-07-01

    The crystal growth of Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F] is being studied for 1.047-{micro}m laser operation. These crystals are not yet routinely available and the growth of high optical quality, low loss crystals poses a challenge due to a number of crystal growth issues, including, cloudiness, bubble core defects, anomalous absorption, low-angle grain boundaries, and cracking. At this time, a growth process has been formulated to simultaneously eliminate or greatly diminish each of the defects yielding high quality material. Laser slabs of dimension 4.0 x 6.0 x 0.75 cm are being fabricated from sub-scale pieces using the diffusion bonding technique.

  7. Growth of garnet crystals for laser applications. Final report, 1 February-31 July 1984

    SciTech Connect

    Khattak, C.P.

    1984-08-01

    The objective of the Phase I effort was to establish feasibility of growth of Gd3Ga5O12(GGG) crystals as a precursor to growth of other garnet crystals, e.g. Gd35c2Ga3O12 (GSGG), for laser applications. Experimental work showed that Ga/sub 2/O/sub 3/ has a high vapor pressure and, therefore, it results in decomposition of GGG prior to meltdown. Introduction of oxygen into the furnace chamber to prevent decomposition was not feasible with existing graphite resistance-heated HEM furnaces. An alternative material in the Al-garnet family, Gd3Sc2Al3O12 (GSAG), was chosen. The higher stability of the melt suggests that low intrinsic defects containing larger crystals of GSAG can be grown as compared to GSGG. This new class of garnet-structured crystals offers potential for high-power, tunable, solid-state laser materials.

  8. Note: Laser beam scanning using a ferroelectric liquid crystal spatial light modulator

    SciTech Connect

    Das, Abhijit; Boruah, Bosanta R.

    2014-04-15

    In this work we describe laser beam scanning using a ferroelectric liquid crystal spatial light modulator. Commercially available ferroelectric liquid crystal spatial light modulators are capable of displaying 85 colored images in 1 s using a time dithering technique. Each colored image, in fact, comprises 24 single bit (black and white) images displayed sequentially. We have used each single bit image to write a binary phase hologram. For a collimated laser beam incident on the hologram, one of the diffracted beams can be made to travel along a user defined direction. We have constructed a beam scanner employing the above arrangement and demonstrated its use to scan a single laser beam in a laser scanning optical sectioning microscope setup.

  9. 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.

  10. The influence of Ag nanoparticles on random laser from dye-doped nematic liquid crystals

    NASA Astrophysics Data System (ADS)

    Ye, Lihua; Liu, Bo; Li, Fangjie; Feng, Yangyang; Cui, Yiping; Lu, Yanqing

    2016-10-01

    The threshold energy and electric field response characteristic of random laser have been investigated in dye-doped nematic liquid crystal (DDNLC) with the addition of different concentrations of Ag nanoparticles (NPs). Due to the localized surface plasmon resonance (LSPR) induced by Ag NPs, random laser from DDNLC with Ag NP doping had a lower threshold energy. From another point of view, nematic liquid crystals (LCs) in a DDNLC cell with the addition of Ag NPs could be more easily influenced by the electric field, which allowed the random laser to be controlled at a lower applied voltage. The turn-off time and turn-on time of random laser also decreased in the DDNLC cells with increasing the concentration of Ag NPs. This is due to the enhancement of the electro-optical characteristic of LC and the restoring force imparted by the locally ordered LCs induced by the Ag NPs, respectively.

  11. Diode-pumped two-frequency lasers based on c-cut vanadate crystals

    SciTech Connect

    Sirotkin, A A; Garnov, Sergei V; Zagumennyi, A I; Zavartsev, Yu D; Kutovoi, S A; Vlasov, V I; Shcherbakov, Ivan A

    2009-09-30

    The luminescent and lasing properties of the neo-dymium ion at the {sup 4}F{sub 3/2}-{sup 4}I{sub 11/2} transition in c-cut vanadate crystals (Nd:YVO{sub 4}, Nd:GdVO{sub 4}, and Nd:Gd{sub 1-x}Y{sub x}VO{sub 4}) are studied. Tuning of the laser radiation wavelength ({Delta}{lambda} = 5.4 nm) is demonstrated. Two-frequency laser schemes with the use of a Lyot filter, a Fabry-Perot etalon, and a Brewster prism as spectral selection elements are proposed and experimentally realised. Stable two-frequency lasing of a laser based on the c-cut Nd:GdVO{sub 4} crystal was obtained in the cw, Q-switched (nanosecond pulses), and active acousto-optic mode-locked (picosecond pulses) regimes. (lasers)

  12. Printed Large-Area Single-Mode Photonic Crystal Bandedge Surface-Emitting Lasers on Silicon.

    PubMed

    Zhao, Deyin; Liu, Shihchia; Yang, Hongjun; Ma, Zhenqiang; Reuterskiöld-Hedlund, Carl; Hammar, Mattias; Zhou, Weidong

    2016-01-04

    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.

  13. Moderate repetition rate ultra-intense laser targets and optics using variable thickness liquid crystal films

    NASA Astrophysics Data System (ADS)

    Poole, P. L.; Willis, C.; Cochran, G. E.; Hanna, R. T.; Andereck, C. D.; Schumacher, D. W.

    2016-10-01

    Liquid crystal films are variable thickness, planar targets for ultra-intense laser matter experiments such as ion acceleration. Their target qualities also make them ideal for high-power laser optics such as plasma mirrors and waveplates. By controlling parameters of film formation, thickness can be varied on-demand from 10 nm to above 50 μm, enabling real-time optimization of laser interactions. Presented here are results using a device that draws films from a bulk liquid crystal source volume with any thickness in the aforementioned range. Films form within 2 μm of the same location each time, well within the Rayleigh range of even tight F / # systems, thus removing the necessity for realignment between shots. The repetition rate of the device exceeds 0.1 Hz for sub-100 nm films, facilitating higher repetition rate operation of modern laser facilities.

  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. Efficient laser emission from cladding waveguide inscribed in Nd:GdVO(4) crystal by direct femtosecond laser writing.

    PubMed

    Liu, Hongliang; Tan, Yang; Vázquez de Aldana, Javier R; Chen, Feng

    2014-08-01

    We report on the fabrication of depressed cladding waveguides in Nd:GdVO(4) laser crystal by using femtosecond laser inscription. The cross section of the structure is a circular shape with a diameter of 150 μm. Under the optical pump at 808 nm, the continuous wave (cw) as well as pulsed (Q-switched by graphene saturable absorber) waveguide lasing at 1064 nm has been realized, supporting guidance of both TE and TM polarizations. The maximum output power of 0.57 W was obtained in the cw regime, while the maximum pulse energy of the pulsed laser emissions was up to 19 nJ (corresponding to a maximum average output power of 0.33 W, at a resonant frequency of 18 MHz). The slope efficiencies achieved for the cw and pulsed Nd:GdVO(4) waveguide lasers were as high as 68% and 52%, respectively. PMID:25078226

  16. Random laser action in stoichiometric Nd3Ga5O12 garnet crystal powder

    NASA Astrophysics Data System (ADS)

    Iparraguirre, I.; Azkargorta, J.; Kamada, K.; Yoshikawa, A.; Rodríguez-Mendoza, U. R.; Lavín, V.; Barredo-Zuriarrain, M.; Balda, R.; Fernández, J.

    2016-03-01

    This work explores the room temperature infrared random laser (RL) performance of Nd3+ ions in a new stoichiometric Nd3Ga5O12 crystal powder. The time-resolved measurements show that the RL pulse is able to follow the subnanosecond oscillations of the pump pulse profile. The pump threshold energy and the absolute stimulated emission energy have been measured using a method developed by the authors. The laser slope efficiency is the highest compared to other Nd3+ stoichiometric RL crystals.

  17. Luminescence of crystals excited by a KrCl laser and a subnanosecond electron beam

    SciTech Connect

    Lipatov, E I; Tarasenko, Viktor F; Orlovskii, Viktor M; Alekseev, S B

    2005-08-31

    Luminescence of crystals of natural spodumene and natural diamond of the type IIa is studied upon excitation by a laser at a wavelength of 222 nm and by a subnanosecond avalanche electron beam (SAEB) formed in air at the atmospheric pressure. The photoluminescence spectra of spodumene and diamond are shown to exhibit additional bands, which are absent upon SAEB excitation. It is demonstrated that SAEB excitation allows one to analyse various crystals under normal conditions without using any vacuum equipment. (interaction of laser radiation with matter)

  18. Sum frequency generation of UV laser radiation at 266  nm in LBO crystal.

    PubMed

    Nikitin, D G; Byalkovskiy, O A; Vershinin, O I; Puyu, P V; Tyrtyshnyy, V A

    2016-04-01

    We report experimental results of generation at 266 nm in LBO crystal by frequency mixing of the fundamental (1064 nm) and third harmonic (355 nm) of ytterbium pulsed fiber laser radiation. Deep ultraviolet (DUV) output power of 3.3 W at 266 nm was achieved with 14% IR-to-DUV conversion efficiency. UV-induced bulk degradation of LBO crystals was observed and visualized by the dark field method. PMID:27192312

  19. Polydimethylsiloxane-enclosed liquid crystal lasers for lab-on-chip applications

    NASA Astrophysics Data System (ADS)

    Schmidtke, Jürgen; Terentjev, Eugene M.

    2010-04-01

    We demonstrate the operation of a self-organized cholesteric liquid crystal laser confined between optically clear and elastic polydimethylsiloxane (PDMS) substrates. The formation of a planar helical texture in the cholesteric was supported by microsctructuring of PDMS layer surface, using the nanoembossing technique with glass substrates coated with conventional alignment layers as a template. The potential of combining miniature cholesteric laser sources and microfluidic devices for lab-on-chip applications is discussed.

  20. Ultrafast-laser-induced surface texturing and crystallization of semiconductors for photovoltaic devices

    NASA Astrophysics Data System (ADS)

    Nayak, Barada K.

    This dissertation discusses the development of a novel laser texturing method that enables fabrication of unique nano/micro surface structures in different material systems and their applications. The primary application described in this work is on the development of improved photovoltaic cells. The interaction of ultrafast lasers in the presence of different reactive and inert gases leads towards formation of nearly regular arrays of conical microstructures (and in some cases nanospikes atop microstructures). These textured surfaces trap the incident light very efficiently in a very broad spectrum (almost 100% over the entire solar spectrum and around 95% in the infrared spectral range of 2.5-25 mum for silicon) and the material looks pitch dark to bare eye. We thoroughly investigated the role of different gases and laser parameters on the formation of these structures and their applications. Laser texturing and crystallization can be achieved as a one step process for amorphous thin film silicon for photovoltaic application. We have also demonstrated the unique capability of low cost semiconductor laser for crystallizing thick silicon films for photovoltaic applications. Laser texturing and crystallization technique has been applied to fabricate efficient thin film solar cells. Encouraging results for cells fabricated in bulk textured silicon has also been observed. Additionally, we have demonstrated three unique applications of this texturing technology: (a) producing superhydrophobic surfaces in titanium and stainless steel; (b) fabrication of arrays of micro/nano holes in silicon; (c) growth and proliferation of stem cells in textured titanium surfaces.

  1. Generation and elimination of polarization-dependent ablation of cubic crystals by femtosecond laser radiation.

    PubMed

    Li, Xin; Rong, Wenlong; Jiang, Lan; Zhang, Kaihu; Li, Cong; Cao, Qiang; Zhang, Guangming; Lu, Yongfeng

    2014-12-01

    We experimentally showed that the π/2-period oscillation of an ablation area with laser polarization direction can be observed in GaAs, ZnSe, MgO and LiF with cubic crystal by a femtosecond laser (800 nm, 100 fs) and that the modulation in the ablation area can be controlled by the laser fluence. While the polarization dependence is sustained in a wide range of laser fluences for a narrow band-gap crystal, it is strongly suppressed with a slight augmentation of laser fluence in a wide band-gap material. The polarization-dependent ablation is explained by the crystal's orientation-dependent reduced-electron mass and the resultant contrasting nonlinear absorptions with slightly different reduced electron mass. The interplay between photoionization and avalanche ionization is discussed to interpret the influence of laser fluence on polarization-dependent ablation. Based on Keldysh's theory, polarization-dependent ablation occurs in a mixed regime between tunneling and multiphoton ionization.

  2. Sensitive detection of malachite green and crystal violet by nonlinear laser wave mixing and capillary electrophoresis.

    PubMed

    Maxwell, Eric J; Tong, William G

    2016-05-01

    An ultrasensitive label-free antibody-free detection method for malachite green and crystal violet is presented using nonlinear laser wave-mixing spectroscopy and capillary zone electrophoresis. Wave-mixing spectroscopy provides a sensitive absorption-based detection method for trace analytes. This is accomplished by forming dynamic gratings within a sample cell, which diffracts light to create a coherent laser-like signal beam with high optical efficiency and high signal-to-noise ratio. A cubic dependence on laser power and square dependence on analyte concentration make wave mixing sensitive enough to detect molecules in their native form without the use of fluorescent labels for signal enhancement. A 532 nm laser and a 635 nm laser were used for malachite green and crystal violet sample excitation. The use of two lasers of different wavelengths allows the method to simultaneously detect both analytes. Selectivity is obtained through the capillary zone electrophoresis separation, which results in characteristic migration times. Measurement in capillary zone electrophoresis resulted in a limit of detection of 6.9 × 10(-10)M (2.5 × 10(-19) mol) for crystal violet and 8.3 × 10(-11)M (3.0 × 10(-20) mol) for malachite green at S/N of 2.

  3. Sensitive detection of malachite green and crystal violet by nonlinear laser wave mixing and capillary electrophoresis.

    PubMed

    Maxwell, Eric J; Tong, William G

    2016-05-01

    An ultrasensitive label-free antibody-free detection method for malachite green and crystal violet is presented using nonlinear laser wave-mixing spectroscopy and capillary zone electrophoresis. Wave-mixing spectroscopy provides a sensitive absorption-based detection method for trace analytes. This is accomplished by forming dynamic gratings within a sample cell, which diffracts light to create a coherent laser-like signal beam with high optical efficiency and high signal-to-noise ratio. A cubic dependence on laser power and square dependence on analyte concentration make wave mixing sensitive enough to detect molecules in their native form without the use of fluorescent labels for signal enhancement. A 532 nm laser and a 635 nm laser were used for malachite green and crystal violet sample excitation. The use of two lasers of different wavelengths allows the method to simultaneously detect both analytes. Selectivity is obtained through the capillary zone electrophoresis separation, which results in characteristic migration times. Measurement in capillary zone electrophoresis resulted in a limit of detection of 6.9 × 10(-10)M (2.5 × 10(-19) mol) for crystal violet and 8.3 × 10(-11)M (3.0 × 10(-20) mol) for malachite green at S/N of 2. PMID:26998858

  4. Tm:GGAG crystal for 2μm tunable diode-pumped laser

    NASA Astrophysics Data System (ADS)

    Šulc, Jan; Boháček, Pavel; Němec, Michal; Fibrich, Martin; Jelínková, Helena; Trunda, Bohumil; Havlák, Lubomír.; Jurek, Karel; Nikl, Martin

    2016-04-01

    The spectroscopy properties and wavelength tunability of diode pumped laser based on Tm-doped mixed gadolinium-gallium-aluminium garnet Gd3(GaxAl1-x)5O12 (Tm:GGAG) single crystal were investigated for the first time. The crystal was grown by Czochralski method in a slightly oxidative atmosphere using an iridium crucible. The tested Tm:GGAG sample was cut from the grown crystal boule perpendicularly to growth direction (c-axis). The composition of sample was determined using electron microprobe X-ray elemental analysis. For spectroscopy and laser experiments 3.5mm thick plane-parallel face-polished plate (without AR coatings) with composition Gd2.76Tm0.0736Ga2.67Al2.50O12 (2.67 at.% Tm/Gd) was used. A fiber (core diameter 400 μm, NA= 0.22) coupled laser diode (emission wavelength 786 nm) was used for longitudinal Tm:GGAG pumping. The laser diode was operating in the pulsed regime (10 ms pulse length, 10 Hz repetition rate, maximum power amplitude 18 W). The 145mm long semi-hemispherical laser resonator consisted of a flat pumping mirror (HR @ 1.8- 2.10 μm, HT @ 0.78 μm) and curved (r = 150mm) output coupler with a reflectivity of » 97% @ 1.8- 2.10 µm. The maximum laser output power amplitude 1.14W was obtained at wavelength 2003nm for absorbed pump power amplitude 4.12W. The laser slope efficiency was 37% in respect to absorbed pumping power. Wavelength tuning was accomplished by using 2mm thick MgF2 birefringent filter placed inside the laser resonator at the Brewster angle. The laser was continuously tunable over 180nm in a spectral region from 1856nm to 2036 nm.

  5. High-power efficient cw and pulsed lasers based on bulk Yb : KYW crystals with end diode pumping

    SciTech Connect

    Kim, G H; Yang, G H; Lee, D S; Kulik, Alexander V; Sall', E G; Chizhov, S A; Yashin, V E; Kang, U

    2012-04-30

    End-diode-pumped lasers based on one and two Yb : KYW crystals operating in cw and Q-switched regimes, as well as in the regime of mode-locking, are studied. The single-crystal laser generated stable ultrashort (shorter than 100 fs) laser pulses at wavelengths of 1035 and 1043 nm with an average power exceeding 1 W. The average output power of the two-crystal laser exceeded 18 W in the cw regime and 16 W in the Q-switched regime with a slope efficiency exceeding 30%.

  6. Laser-Aided Direct Writing of Nickel-Based Single-Crystal Super Alloy (N5)

    NASA Astrophysics Data System (ADS)

    Wang, Yichen; Choi, Jeongyoung; Mazumder, Jyoti

    2016-09-01

    This communication reports direct writing of René N5 nickel-based Super alloy. N5 powder was deposited on (100) single-crystal substrate of René N5, for epitaxial growth, using laser and induction heating with a specially designed closed-loop thermal control system. A thin wall (1 mm width) of René N5 single crystal of 22.1 mm (including 3 mm SX substrate) in height was successfully deposited within 100 layers. SEM and EBSD characterized the single-crystal nature of the deposit.

  7. Effect of medium range order on pulsed laser crystallization of amorphous germanium thin films

    DOE PAGES

    Li, T. T.; Bayu Aji, L. B.; Heo, T. W.; Santala, M. K.; Kucheyev, S. O.; Campbell, G. H.

    2016-06-03

    Sputter deposited amorphous Ge thin films had their nanostructure altered by irradiation with high-energy Ar+ ions. The change in the structure resulted in a reduction in medium range order (MRO) characterized using fluctuation electron microscopy. The pulsed laser crystallization kinetics of the as-deposited versus irradiated materials were investigated using the dynamic transmission electron microscope operated in the multi-frame movie mode. In conclusion, the propagation rate of the crystallization front for the irradiated material was lower; the changes were correlated to the MRO difference and formation of a thin liquid layer during crystallization.

  8. Large-mode-area Yb3+-doped photonic crystal fiber laser

    NASA Astrophysics Data System (ADS)

    Yan, Pei-Guang; Zhang, Wei; Li, Yi-Gang; Zhu, Jianping; Ding, Lei; Chen, Sheng-Ping; Lu, Kecheng; Dong, Susan

    2005-01-01

    In this paper a large mode area Yb3+-doped double cladding photonic crystal fiber laser is reported. The laser's output power reaches as high as 4.3W. The slope efficiency and the maximum optical-to-optical efficiency of laser output are 69.4% and 59.7%, respectively, with respect to absorbed pump power. Single transverse mode operation is obtained at central wavelength of 1072.3nm and the measured mode distribution agrees with the simulation by using scalar beam propagation method.

  9. Two-dimensional colloid-based photonic crystals for distributed feedback polymer lasers

    SciTech Connect

    Mafouana, Rodrigue; Rehspringer, Jean-Luc; Hirlimann, Charles; Estournes, Claude; Dorkenoo, Kokou D.

    2004-11-08

    We report on a process to design highly ordered monolayers of two-dimensional photonic crystals, made of silica nanoparticules, that can be used for the development of organic optical devices. We have used a photopolymerization process to incorporate a dye gain medium into the nanoparticle layers in order to achieve a laser cavity. The high spatial coherence of the deposits allows for single-mode laser emission in the plane of the layer when the light excitation is perpendicular to the plane. Such periodic films should help in reducing the number of layers needed for future electrically pumped distributed feedback lasers.

  10. Laser damage threshold and nonlinear optical properties of large aperture elements of YCOB crystal

    NASA Astrophysics Data System (ADS)

    Zheng, Yanqing; Wu, Anhua; Gao, Pan; Tu, Xiaoniu; Liang, Xiaoyan; Hou, Jing; Yang, Liming; Wang, Tao; Qian, Liejia; Shi, Erwei

    2012-01-01

    Large size of YCa4O(BO3)3(YCOB) crystals were grown both by Czochralski and Bridgman methods. Large size elements as large as 60 mm clear aperture were cut and polished with surface flatness of 1/5 wavelength. Optical homogeneity of YCOB crystal was found in the order of 10-6. Laser damage thresholds of several YCOB crystal elements were tested using different laser facilities with different pulse widths or wavelengths, with thresholds varied from 0.8 GW/cm2 to more than 1 TW/cm2. One SHG and two optical parametric chirped-pulse amplification (OPCPA) experiments were executed to characterize the nonlinear optical properties of YCOB crystals and the quality of the crystals. The results shown that YCOB had good performance in OPCPA application, especially with low content of parameter florescence. Combined with good NLO performance and possibility to grow large size crystals, YCOB crystal was a good choice for high power OPCPA applications.

  11. Laser damage threshold and nonlinear optical properties of large aperture elements of YCOB crystal

    NASA Astrophysics Data System (ADS)

    Zheng, Yanqing; Wu, Anhua; Gao, Pan; Tu, Xiaoniu; Liang, Xiaoyan; Hou, Jing; Yang, Liming; Wang, Tao; Qian, Liejia; Shi, Erwei

    2011-11-01

    Large size of YCa4O(BO3)3(YCOB) crystals were grown both by Czochralski and Bridgman methods. Large size elements as large as 60 mm clear aperture were cut and polished with surface flatness of 1/5 wavelength. Optical homogeneity of YCOB crystal was found in the order of 10-6. Laser damage thresholds of several YCOB crystal elements were tested using different laser facilities with different pulse widths or wavelengths, with thresholds varied from 0.8 GW/cm2 to more than 1 TW/cm2. One SHG and two optical parametric chirped-pulse amplification (OPCPA) experiments were executed to characterize the nonlinear optical properties of YCOB crystals and the quality of the crystals. The results shown that YCOB had good performance in OPCPA application, especially with low content of parameter florescence. Combined with good NLO performance and possibility to grow large size crystals, YCOB crystal was a good choice for high power OPCPA applications.

  12. Batch crystallization of rhodopsin for structural dynamics using an X-ray free-electron laser

    SciTech Connect

    Wu, Wenting; Nogly, Przemyslaw; Rheinberger, Jan; Kick, Leonhard M.; Gati, Cornelius; Nelson, Garrett; Deupi, Xavier; Standfuss, Jörg; Schertler, Gebhard; Panneels, Valérie

    2015-06-27

    A new batch preparation method is presented for high-density micrometre-sized crystals of the G protein-coupled receptor rhodopsin for use in time-resolved serial femtosecond crystallography at an X-ray free-electron laser using a liquid jet. Rhodopsin is a membrane protein from the G protein-coupled receptor family. Together with its ligand retinal, it forms the visual pigment responsible for night vision. In order to perform ultrafast dynamics studies, a time-resolved serial femtosecond crystallography method is required owing to the nonreversible activation of rhodopsin. In such an approach, microcrystals in suspension are delivered into the X-ray pulses of an X-ray free-electron laser (XFEL) after a precise photoactivation delay. Here, a millilitre batch production of high-density microcrystals was developed by four methodical conversion steps starting from known vapour-diffusion crystallization protocols: (i) screening the low-salt crystallization conditions preferred for serial crystallography by vapour diffusion, (ii) optimization of batch crystallization, (iii) testing the crystal size and quality using second-harmonic generation (SHG) imaging and X-ray powder diffraction and (iv) production of millilitres of rhodopsin crystal suspension in batches for serial crystallography tests; these crystals diffracted at an XFEL at the Linac Coherent Light Source using a liquid-jet setup.

  13. Analog Experiments on Sulfide Foams in Magmatic Ore Deposits

    NASA Astrophysics Data System (ADS)

    Leitch, A. M.; Dahn, D.; Zavala, K.

    2009-05-01

    Metal sulfides form as an immiscible phase from silicate magmas. Dynamic mingling and unmingling of the two phases is important for the development of economic deposits: mingling promotes enrichment of the sulfide in valuable metals, and subsequent unmingling generates massive sulfide. Analog experiments were carried out to investigate mingling processes in immiscible systems, using oil, water and small beads to represent magma, sulfide liquid and silicate crystals. Stirring or injection led to the formation of a foam of analog sulfide droplets within an analog silicate framework. We propose that the partial collapse of such a foam explains massive sulfide lenses at the Voisey's Bay magmatic sulfide deposit, and that crystallization of silicate crystals in the remaining foam walls generates 'net-textured' ores. In the experiments, solid particles had a profound effect on unmingling: analog sulfide droplets were stably contained within analog crystal-rich magma and did not coalesce. We therefore suggest that 'net' and 'leopard' textures in disseminated sulfides indicate mingling of sulfide with crystal-poor magma, whereas isolated disseminated patches of sulfide indicate mingling with a crystal-rich magma.

  14. Microchip laser based on Yb:YAG/V:YAG monolith crystal

    NASA Astrophysics Data System (ADS)

    Nejezchleb, Karel; Šulc, Jan; Jelínková, Helena; Škoda, Václav

    2016-03-01

    V:YAG crystal was investigated as a passive Q-switch of longitudinally diode-pumped microchip laser, emitting radiation at wavelength 1030.5 nm. This laser was based on diffusion bonded monolith crystal (diameter 3 mm) which combines in one piece an active laser part (Yb:YAG crystal, 10 at.% Yb/Y, 3 mm long) and saturable absorber (V:YAG crystal, 2 mm long, initial transmission 86 % @ 1031 nm). The microchip resonator consisted of dielectric mirrors directly deposited on the monolith surfaces (pump mirror HT @ 968 nm and HR @ 1031 nm on Yb:YAG part, output coupler with reflection 55 % @ 1031 nm on the V:YAG part). For longitudinal CW pumping of Yb:YAG part, a fibre coupled (core diameter 100 μm, NA = 0.22, emission @ 968 nm) laser diode was used. The laser threshold was 3.8W. The laser slope efficiency for output mean in respect to incident pumping was 16 %. The linearly polarized generated transversal intensity beam profile was close to the fundamental Gaussian mode. The generated pulse length, stable and mostly independent on pumping power, was equal to 1.3 ns (FWHM). The single pulse energy was increasing with the pumping power and for the maximum pumping 9.7W it was 78 μJ which corresponds to the pulse peak-power 56 kW. The maximum Yb:YAG/V:YAG microchip laser mean output power of 1W was reached without observable thermal roll-over. The corresponding Q-switched pulses repetition rate was 13.1 kHz.

  15. Stoichiometric changes in KH2PO4 crystals during laser-induced breakdown

    SciTech Connect

    Negres, R A; Kucheyev, S O; DeMange, P; Bostedt, C; van Buuren, T; Nelson, A J; Demos, S G

    2004-08-31

    The structure of KH{sub 2}PO{sub 4} single crystals (so-called KDP) irradiated with {approx} 3-ns, 355-nm laser pulses with fluences above the laser-induced breakdown threshold is studied by a combination of Raman scattering, photoluminescence, and soft x-ray absorption spectroscopies. We compare spectra from the as-grown material, surface and bulk laser-induced damage sites, as well as from KPO{sub 3} references. Results show that irradiation with fluences above the laser-induced breakdown threshold leads to stoichiometric changes at surface damage sites but not at bulk damage sites. New spectroscopic features are attributed to dehydration products. For the laser irradiation conditions used in this study, the decomposed near-surface layer absorbs photons at {approx} 3.4 eV (364 nm). These results may explain the recently reported fact that surface laser damage sites in KDP crystals tend to grow with subsequent exposure to high-power laser pulses, while bulk damage sites do not.

  16. Ferromagnetism in SrTiO3 Single Crystals Induced by Laser irradiation

    NASA Astrophysics Data System (ADS)

    Singamaneni, Srinivasa Rao; Lee, Y. F.; Prater, J. T.; Smirnov, A. I.; Narayan, J.

    2015-03-01

    SrTiO3 (STO) is diamagnetic in pristine state, important in emerging field of complex oxide electronics. No attention has been paid to explore the magnetic properties of STO crystal upon laser irradiation/annealing. In this presentation, we demonstrate that STO single crystals show ferromagnetic order up to 400 K upon KrF (248 nm) laser irradiation. The high resolution x-ray photo emission spectroscopy (XPS) measurements reveal a strong shift of Sr-, Ti- and O-related peaks. X-ray diffraction (XRD) of laser annealed STO does not reveal a signature of either secondary magnetic or amorphous phases. 300 K X-band (~ 9.543 GHz) angle-dependent electron paramagnetic resonance (EPR) measurements showed no evidence of additional magnetic peaks up on laser irradiation. XPS and EPR data did not provide a strong evidence of Ti3+ formation upon laser annealing. No differences in the visible 300 K Raman spectra of pristine and laser annealed STO are noticed. Interestingly, the magnetic moment is decreased by almost 10-fold upon oxygen annealing of laser annealed STO, inferring that oxygen vacancies play an important role in establishing the observed ferromagnetism.

  17. Phase locking and supermode selection in multicore photonic crystal fiber lasers with a large doped area.

    PubMed

    Michaille, L; Bennett, C R; Taylor, D M; Shepherd, T J; Broeng, J; Simonsen, H R; Petersson, A

    2005-07-01

    We report on the laser properties of multicore photonic crystal fiber lasers. A stable phase locking of six- and seven-core structures through evanescent coupling is observed. Effective supermode selection is obtained by using both diffraction losses and the Talbot effect. A pure in-phase supermode is obtained (1.1 times diffraction limited). The laser operating in this mode has a slope efficiency of 70% with up to 44 W of output power. The modal area of the in-phase supermode multicore fiber is 1150 microm2, which makes it, to our knowledge, the single-mode fiber laser with the largest mode field area. In-phase laser action is stable when the fiber is bent. PMID:16075532

  18. Multiwavelength L-band fiber laser with bismuth-oxide EDF and photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Ramzia Salem, A. M.; Al-Mansoori, M. H.; Hizam, H.; Mohd Noor, S. B.; Abu Bakar, M. H.; Mahdi, M. A.

    2011-05-01

    A multiwavelength laser comb using a bismuth-based erbium-doped fiber and 50 m photonic crystal fiber is demonstrated in a ring cavity configuration. The fiber laser is solely pumped by a single 1455 nm Raman pump laser to exploit its higher power delivery compared to that of a single-mode laser diode pump. At 264 mW Raman pump power and 1 mW Brillouin pump power, 38 output channels in the L-band have been realized with an optical signal-to-noise ratio above 15 dB and a Stokes line spacing of 0.08 nm. The laser exhibits a tuning range of 12 nm and produces stable Stokes lines across the tuning range between Brillouin pump wavelengths of 1603 nm and 1615 nm.

  19. Crystallization to polycrystalline silicon thin film and simultaneous inactivation of electrical defects by underwater laser annealing

    NASA Astrophysics Data System (ADS)

    Machida, Emi; Horita, Masahiro; Ishikawa, Yasuaki; Uraoka, Yukiharu; Ikenoue, Hiroshi

    2012-12-01

    We propose a low-temperature laser annealing method of a underwater laser annealing (WLA) for polycrystalline silicon (poly-Si) films. We performed crystallization to poly-Si films by laser irradiation in flowing deionized-water where KrF excimer laser was used for annealing. We demonstrated that the maximum value of maximum grain size of WLA samples was 1.5 μm, and that of the average grain size was 2.8 times larger than that of conventional laser annealing in air (LA) samples. Moreover, WLA forms poly-Si films which show lower conductivity and larger carrier life time attributed to fewer electrical defects as compared to LA poly-Si films.

  20. Crystallization to polycrystalline silicon thin film and simultaneous inactivation of electrical defects by underwater laser annealing

    SciTech Connect

    Machida, Emi; Horita, Masahiro; Ishikawa, Yasuaki; Uraoka, Yukiharu; Ikenoue, Hiroshi

    2012-12-17

    We propose a low-temperature laser annealing method of a underwater laser annealing (WLA) for polycrystalline silicon (poly-Si) films. We performed crystallization to poly-Si films by laser irradiation in flowing deionized-water where KrF excimer laser was used for annealing. We demonstrated that the maximum value of maximum grain size of WLA samples was 1.5 {mu}m, and that of the average grain size was 2.8 times larger than that of conventional laser annealing in air (LA) samples. Moreover, WLA forms poly-Si films which show lower conductivity and larger carrier life time attributed to fewer electrical defects as compared to LA poly-Si films.

  1. Sympathetic cooling of laser-produced doubly charged ions in a few-ion crystal

    SciTech Connect

    Kwapien, T.; Eichmann, U.; Sandner, W.

    2007-06-15

    We present experimental results in which single Ca{sup +} ions in a chain of laser cooled Ca{sup +} ions are further ionized by means of an intense short pulse laser. The ions are trapped in a linear Paul trap, which is instantaneously loaded by ions from a laser-produced ablation plasma. Due to sympathetic cooling the doubly charged ions are held in place. We study and characterize linear few-ion crystals with mixed charges by applying a radio frequency field, which excites the center of mass (c.m.) and breathing modes of different configurations. From the position shift of laser cooled ions initiated through the higher charge state we can deduce the charge of the nonfluorescing ion. This information might be used as an intensity probe for high intensity lasers.

  2. Tailoring the crystal structure of individual silicon nanowires by polarized laser annealing.

    PubMed

    Chang, Chia-Chi; Chen, Haitian; Chen, Chun-Chung; Hung, Wei-Hsuan; Hsu, I-Kai; Theiss, Jesse; Zhou, Chongwu; Cronin, Stephen B

    2011-07-29

    We study the effect of polarized laser annealing on the crystalline structure of individual crystalline-amorphous core-shell silicon nanowires (NWs) using Raman spectroscopy. The crystalline fraction of the annealed spot increases dramatically from 0 to 0.93 with increasing incident laser power. We observe Raman lineshape narrowing and frequency hardening upon laser annealing due to the growth of the crystalline core, which is confirmed by high resolution transmission electron microscopy (HRTEM). The anti-Stokes:Stokes Raman intensity ratio is used to determine the local heating temperature caused by the intense focused laser, which exhibits a strong polarization dependence in Si NWs. The most efficient annealing occurs when the laser polarization is aligned along the axis of the NWs, which results in an amorphous-crystalline interface less than 0.5 µm in length. This paper demonstrates a new approach to control the crystal structure of NWs on the sub-micron length scale.

  3. Recent advancements in transparent ceramics and crystal fibers for high power lasers

    NASA Astrophysics Data System (ADS)

    Kim, W.; Baker, C.; Villalobos, G.; Florea, C.; Gibson, D.; Shaw, L. B.; Bowman, S.; Bayya, S.; Sadowski, B.; Hunt, M.; Askins, C.; Peele, J.; Aggarwal, I. D.; Sanghera, J. S.

    2013-05-01

    In this paper, we present our recent progress in the development of rare-earth (Yb3+ or Ho3+) doped Lu2O3 and Y2O3 sesquioxides for high power solid state lasers. We have fabricated high quality transparent ceramics using nano-powders synthesized by a co-precipitation method. This was accomplished by developments in high purity powder synthesis and low temperature scalable sintering technology developed at NRL. The optical, spectral and morphological properties as well as the lasing performance from our highly transparent ceramics are presented. In the second part of the paper, we discuss our recent research effort in developing cladded-single crystal fibers for high power single frequency fiber lasers has the potential to significantly exceed the capabilities of existing silica fiber based lasers. Single crystal fiber cores with diameters as small as 35μm have been drawn using high purity rare earth doped ceramic or single crystal feed rods by the Laser Heated Pedestal Growth (LHPG) process. Our recent results on the development of suitable claddings on the crystal fiber core are discussed.

  4. Retrograde Evolution of the Hemlo Gold Deposit, Ontario: Fractional Crystallization of a Sulfide Melt and Remobilization of Ore-Related Metals

    NASA Astrophysics Data System (ADS)

    Heiligmann, M.; Clark, J. R.; Williams-Jones, A. E.

    2003-12-01

    The Hemlo gold deposit is a greenstone-hosted, lode-gold system in north-central Ontario, Canada. The main stage of gold mineralization occurred prior to peak, amphibolite-facies metamorphism, and is characterized by disseminated Au-Mo in potassically altered, barite- and pyrite-rich schists. Locally extensive remobilization of this ore occurred at or immediately after peak metamorphism ( ˜630° C, 5-6 kb), and is represented by minerals such as stibnite, realgar, orpiment, zinkenite and cinnabar, which are unstable at high temperature. Volumetrically minor gold was subsequently precipitated in calc-silicate zones at ˜400° C. Minerals reflecting early remobilization occur either at grain boundaries or as solid inclusions along healed fractures devoid of fluid inclusions. Planes of solid inclusions, many of which are polyphase, radiate locally from the boundaries of large polyphase sulfide aggregates. Inclusions containing both liquid and sulfides are observed mainly at intersections of planes of solid-only and liquid-vapor inclusions. Solid inclusions are characterized by complex assemblages in the system As-Sb-Pb-S, that reflect contrasting conditions of fS2 and fO2. The low thermal stability of many of these minerals, the absence of liquid in the solid inclusion trails, the excessive hydrothermal solubility of stibnite above 300° C, and the evidence of contrasting fS2 and fO2 rule out hydrothermal processes as the cause of this remobilization. We therefore propose that the latter was the result of formation of an As-Sb-Pb-S melt, at or near peak metamorphic conditions, containing minor proportions of Au, Hg, Ag, Cu, Tl and Te, and support this hypothesis with results of preliminary experiments showing that realgar-stibnite-cinnabar-bearing solids homogenize to liquid at ˜435° C. The melt is envisaged to have formed as a result of exsolution of elements such as As, Sb and Au from arsenian pyrite during metamorphic recrystallization, melting of primary

  5. THz quantum cascade lasers operating on the radiative modes of a 2D photonic crystal.

    PubMed

    Halioua, Y; Xu, G; Moumdji, S; Li, L H; Davies, A G; Linfield, E H; Colombelli, R

    2014-07-01

    Photonic-crystal lasers operating on Γ-point band-edge states of a photonic structure naturally exploit the so-called "nonradiative" modes. As the surface output coupling efficiency of these modes is low, they have relatively high Q factors, which favor lasing. We propose a new 2D photonic-crystal design that is capable of reversing this mode competition and achieving lasing on the radiative modes instead. Previously, this has only been shown in 1D structures, where the central idea is to introduce anisotropy into the system, both at unit-cell and resonator scales. By applying this concept to 2D photonic-crystal patterned terahertz frequency quantum cascade lasers, surface-emitting devices with diffraction-limited beams are demonstrated, with 17 mW peak output power.

  6. Optical properties of Dy3+ ion in PbF2 laser crystal

    NASA Astrophysics Data System (ADS)

    Chen, G. Z.; Yin, J. G.; Zhang, L. H.; He, M. Z.; Ma, E.; Ning, K. J.; Zhang, P. X.; Liu, Y. C.; Hang, Y.

    2013-11-01

    High-quality Dy:PbF2 crystal is grown by the Bridgman method in a nonvacuum atmosphere. By measuring the area under absorption bands, the experimental oscillator strengths are determined. The Judd-Ofelt (JO) intensity parameters Ωλ (λ = 2, 4, 6) are evaluated by the least-squares fit method. These phenomenological parameters are used to predict radiative transition probabilities, radiative lifetime and branching ratios for various excited levels of the Dy3+:PbF2 crystal. Photoluminescence spectra and lifetime of 6H13/2 levels of the Dy3+ ions have been measured. The laser transitions with most potential are identified and the utility of the PbF2 crystal as laser active material is discussed.

  7. Crystallization kinetics of GeTe phase-change thin films grown by pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Sun, Xinxing; Thelander, Erik; Gerlach, Jürgen W.; Decker, Ulrich; Rauschenbach, Bernd

    2015-07-01

    Pulsed laser deposition was employed to the growth of GeTe thin films on Silicon substrates. X-ray diffraction measurements reveal that the critical crystallization temperature lies between 220 and 240 °C. Differential scanning calorimetry was used to investigate the crystallization kinetics of the as-deposited films, determining the activation energy to be 3.14 eV. Optical reflectivity and in situ resistance measurements exhibited a high reflectivity contrast of ~21% and 3-4 orders of magnitude drop in resistivity of the films upon crystallization. The results show that pulsed laser deposited GeTe films can be a promising candidate for phase-change applications.

  8. Charge transfer processes and ultraviolet induced absorption in Yb:YAG single crystal laser materials

    NASA Astrophysics Data System (ADS)

    Rydberg, S.; Engholm, M.

    2013-06-01

    Charge transfer (CT) transitions and UV induced color centers in Yb:YAG single crystals have been investigated. A simultaneous pair formation of a stable Yb2+ ion and a hole related (O-) color center (hole polaron) are observed through a CT-process. Slightly different types of hole related color centers are formed in Yb:YAG crystals containing small levels of iron impurities. Furthermore, excitation spectroscopy on the UV irradiated Yb:YAG samples could confirm an energy transfer process between Yb3+ and Yb2+ ions. The findings are important for an increased knowledge of the physical loss mechanisms observed in Yb-doped laser materials, such as the nonlinear decay process in Yb:YAG crystals as well as the photodarkening phenomenon in Yb-doped fiber lasers.

  9. Third-order photonic-crystal distributed-feedback quantum cascade lasers

    NASA Astrophysics Data System (ADS)

    Zhang, J. C.; Liu, F. Q.; Wang, L. J.; Zhao, L. H.; Liu, W. F.; Liu, J. Q.; Li, L.; Wang, Z. G.

    2012-10-01

    We demonstrate room-temperature operation of broad-area edge-emitting photonic-crystal distributed-feedback quantum cascade lasers at λ ∼ 4.6 μm. The lasers use a weak-index perturbed third-order photonic-crystal lattice to control the optical mode in the wafer plane. Utilizing this coupling mechanism, the near-diffraction-limited beam quality with a far-field profile normal to the facet can be obtained. Single-mode operation with a signal-to-noise ratio of about 20 dB is achieved in the temperature range of 85-290 K. The single-facet output power is above 1 W for a 55 μm × 2.5 mm laser bar at 85 K in pulsed mode.

  10. Simple model of laser damage initiation and conditioning in frequency conversion crystals

    SciTech Connect

    Feit, M D; Rubenchik, A M; Trenholme, J B

    2005-10-28

    Laser conditioning, i.e. pre-exposure to less than damaging laser fluence, has been shown to improve the damage resistance of KDP/DKDP frequency conversion crystals. We have extended our damage model, small absorbing precursors with a distribution of sizes, to describe various damage related properties such as damage density and effects of laser conditioning in crystals. The model assumes the rate limiting process for both initiation and conditioning depends on temperature and that separate threshold temperatures exist for either conditioning or damage initiation to occur. This is reasonable in KDP/DKDP since the melting temperature is far below the temperatures associated with plasma formation and damage events. This model is capable of accounting for some recently observed damage-conditioning behaviors.

  11. Liquid immiscibility between arsenide and sulfide melts: evidence from a LA-ICP-MS study in magmatic deposits at Serranía de Ronda (Spain)

    NASA Astrophysics Data System (ADS)

    Piña, R.; Gervilla, F.; Barnes, S.-J.; Ortega, L.; Lunar, R.

    2015-03-01

    The chromite-Ni arsenide (Cr-Ni-As) and sulfide-graphite (S-G) deposits from the Serranía de Ronda (Málaga, South Spain) contain an arsenide assemblage (nickeline, maucherite and nickeliferous löllingite) that has been interpreted to represent an arsenide melt and a sulfide-graphite assemblage (pyrrhotite, pentlandite, chalcopyrite and graphite) that has been interpreted to represent a sulfide melt, both of which have been interpreted to have segregated as immiscible liquids from an arsenic-rich sulfide melt. We have determined the platinum-group element (PGE), Au, Ag, Se, Sb, Bi and Te contents of the arsenide and sulfide assemblages using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to establish their partitioning behaviour during the immiscibility of an arsenide melt from a sulfide melt. Previous experimental work has shown that PGE partition more strongly into arsenide melts than into sulfide melts and our results fit with this observation. Arsenide minerals are enriched in all PGE, but especially in elements with the strongest affinity for the arsenide melt, including Ir, Rh and Pt. In contrast and also in agreement with previous studies, Se and Ag partition preferentially into the sulfide assemblage. The PGE-depleted nature of sulfides in the S-G deposits along with the discordant morphologies of the bodies suggest that these sulfides are not mantle sulfides, but that they represent the crystallization product of a PGE-depleted sulfide melt due to the sequestering of PGE by an arsenide melt.

  12. Minimally invasive treatment of pilonidal disease: crystallized phenol and laser depilation.

    PubMed

    Girgin, Mustafa; Kanat, Burhan Hakan; Ayten, Refik; Cetinkaya, Ziya; Kanat, Zekiye; Bozdağ, Ahmet; Turkoglu, Ahmet; Ilhan, Yavuz Selim

    2012-01-01

    Pilonidal disease has been treated surgically and by various other methods for many years. The most important problem associated with such treatment is recurrence, but cosmetic outcome is another important issue that cannot be ignored. Today, crystallized phenol is recognized as a treatment option associated with good medical and cosmetic outcomes. We hypothesized that the addition of laser depilation to crystallized phenol treatment of pilonidal disease might increase the rate of success, and this study aimed to determine if the hypothesis was true. Patients who were treated with crystallized phenol and 755-nm alexandrite laser depilation were retrospectively analyzed. In total, 42 (31 male and 11 female) patients were treated with crystallized phenol and alexandrite laser depilation and were followed up between January 2009 and January 2012. In all, 38 patients (90.5%) had chronic disease and 4 (9.5%) had recurrent disease. Among the patients, 26 (61.9%) recovered following 1 crystallized phenol treatment, and the remaining patients had complete remission following repeated treatment. Some patients needed multiple treatments, even up to 8 times. None of the patients had a recurrence during a mean 24 months (range, 6-30 months) of follow-up. Whatever method of treatment is used for pilonidal disease, hair cleaning positively affects treatment outcome. The present results support the hypothesis that the addition of laser depilation (which provides more permanent and effective depilation than other methods) to crystallized phenol treatment (a non-radical, minimally invasive method associated with very good cosmetic results) can increase the effectiveness of the treatment and also reduce the recurrence rate of the disease. PMID:23294066

  13. Resonance laser-plasma excitation of coherent terahertz phonons in the bulk of fluorine-bearing crystals under high-intensity femtosecond laser irradiation

    SciTech Connect

    Potemkin, F V; Mareev, E I; Khodakovskii, N G; Mikheev, P M

    2013-08-31

    The dynamics of coherent phonons in fluorine-containing crystals was investigated by pump-probe technique in the plasma production regime. Several phonon modes, whose frequencies are overtones of the 0.38-THz fundamental frequency, were simultaneously observed in a lithium fluoride crystal. Phonons with frequencies of 1 and 0.1 THz were discovered in a calcium fluoride crystal and coherent phonons with frequencies of 1 THz and 67 GHz were observed in a barium fluoride crystal. Furthermore, in the latter case the amplitudes of phonon mode oscillations were found to significantly increase 15 ps after laser irradiation. (interaction of laser radiation with matter)

  14. Crystal orientation dependence of femtosecond laser-induced periodic surface structure on (100) silicon.

    PubMed

    Jiang, Lan; Han, Weina; Li, Xiaowei; Wang, Qingsong; Meng, Fantong; Lu, Yongfeng

    2014-06-01

    It is widely believed that laser-induced periodic surface structures (LIPSS) are independent of material crystal structures. This Letter reports an abnormal phenomenon of strong dependence of the anisotropic formation of periodic ripples on crystal orientation, when Si (100) is processed by a linearly polarized femtosecond laser (800 nm, 50 fs, 1 kHz). LIPSS formation sensitivity with a π/2 modulation is found along different crystal orientations with a quasi-cosinusoid function when the angle between the crystal orientation and polarization direction is changed from 0° to 180°. Our experiments indicate that it is much easier (or more difficult) to form ripple structures when the polarization direction is aligned with the lattice axis [011]/[011¯] (or [001]). The modulated nonlinear ionization rate along different crystal orientations, which arises from the direction dependence of the effective mass of the electron is proposed to interpret the unexpected anisotropic LIPSS formation phenomenon. Also, we demonstrate that the abnormal phenomenon can be applied to control the continuity of scanned ripple lines along different crystal orientations.

  15. Pure, single crystal Ge nanodots formed using a sandwich structure via pulsed UV excimer laser annealing

    NASA Astrophysics Data System (ADS)

    Liao, Ting-Wei; Chen, Hung-Ming; Shen, Kuan-Yuan; Kuan, Chieh-Hsiung

    2015-04-01

    In this paper, a sandwich structure comprising a SiO2 capping layer, amorphous Germanium (a-Ge) nanodots (NDs), and a pit-patterned Silicon (Si) substrate is developed, which is then annealed by utilizing a pulsed ultraviolet excimer laser in order to fabricate an array of pure, single crystal Ge NDs at room temperature. A wide bandgap SiO2 capping layer is used as a transparent thermally isolated layer to prevent thermal loss and Si-Ge intermixing. The two-dimensional pit-patterned Si substrate is designed to confine the absorbed laser energy, reduce the melting point, and block the surface migration of the Ge. After optimizing the laser radiation parameters such that the laser energy density is 200 mJ cm-2, the laser annealing period is 10 s, and the number of laser shots is 10, pure, single crystal Ge NDs that have both a regular arrangement and a uniform size distribution are obtained in the pits of the Si substrates. The Raman spectrum shows a highly symmetric Ge transversal optical peak with a full width at half maximum of 4.2 cm-1 at 300.7 cm-1, which is close to that of the original Ge wafer. In addition, the high-resolution transmission electron microscopy image for the Ge NDs and the corresponding selected area electron diffraction pattern shows a clear single crystalline structure without any impurities.

  16. Carbonyl sulfide

    Integrated Risk Information System (IRIS)

    Carbonyl sulfide ; CASRN 463 - 58 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  17. Hydrogen sulfide

    Integrated Risk Information System (IRIS)

    Hydrogen sulfide ; 7783 - 06 - 4 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effec

  18. Selenium sulfide

    Integrated Risk Information System (IRIS)

    Selenium sulfide ; CASRN 7446 - 34 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic

  19. Performance of the x-ray free-electron laser oscillator with crystal cavity

    NASA Astrophysics Data System (ADS)

    Lindberg, R. R.; Kim, K.-J.; Shvyd'Ko, Yu.; Fawley, W. M.

    2011-01-01

    Simulations of the x-ray free-electron laser (FEL) oscillator are presented that include the frequency-dependent Bragg crystal reflectivity and the transverse diffraction and focusing using the two-dimensional FEL code GINGER. A review of the physics of Bragg crystal reflectors and the x-ray FEL oscillator is made, followed by a discussion of its numerical implementation in GINGER. The simulation results for a two-crystal cavity and realistic FEL parameters indicate ˜109 photons in a nearly Fourier-limited, ps pulse. Compressing the electron beam to 100 A and 100 fs results in comparable x-ray characteristics for relaxed beam emittance, energy spread, and/or undulator parameters, albeit in a larger radiation bandwidth. Finally, preliminary simulation results indicate that the four-crystal FEL cavity can be tuned in energy over a range of a few percent.

  20. Photonic crystal design and fabrication assisted by tunable femtosecond oscillator laser

    NASA Astrophysics Data System (ADS)

    Ohlinger, Kristofer B.

    Photonic Crystals have the potential for engineered light interaction as directed by the photonic bandgap, a property that details the prohibited propagation region and ultimately the ability to guide light. A so called, photonics-on-chip, would incorporate arbitrary light guiding with functional elements in one package. The realization of such a device is subject to the fabrication paradigms implemented and this thesis is concerned with holographic lithography as a means for creating polymer photonics crystal templates and two-photon polymerization for incorporating light guiding pathways. In this thesis, the design of the to-be-fabricated structures has been co-opted by computational exploration of the photonic crystals possible under the fabrication paradigms with the photonic bandgap considered as a target for design optimization, and tolerancing. Introduction of defects into photonic crystal templates has been successfully realized with the assistance of a tunable femtosecond oscillator laser after the processing conditions have been investigated and demonstrated.

  1. Phosphate Yb3+ photonic crystal fiber single-mode laser with enormous high pump absorption

    NASA Astrophysics Data System (ADS)

    Franczyk, M.; Stepien, R.; Pysz, D.; Kujawa, I.; Buczynski, R.

    2014-08-01

    We demonstrate a single-mode 6 cm long, phosphate fiber laser with maximum power of 9.0 W. Laser action output power per fiber length of 150 W m-1 was achieved and this is the highest value ever reported in a single-mode fiber laser using a phosphate glass fiber. The slope efficiency of the laser was 36.2% and lasing wavelength was 1028 nm. We used a 6% mol ytterbium-doped, air-clad photonic crystal fiber with the core of 30 µm in diameter. Estimated pump absorption in the fiber exceeded 400 dB m-1.

  2. Variable Thickness Liquid Crystal Films for High Repetition Rate Laser Applications

    NASA Astrophysics Data System (ADS)

    Poole, Patrick; Willis, Christopher; Cochran, Ginevra; Hanna, Randall; Andereck, C. David; Schumacher, Douglass

    2015-05-01

    The presentation of a clean target or target substrate at high repetition rates is of importance to a number of photoelectron spectroscopy and free electron laser applications, often in high vacuum environments. Additionally, high intensity laser facilities are approaching the 10 Hz shot rate at petawatt powers, but are currently unable to insert targets at these rates. We have developed liquid crystal films to address this need for high rep rate targets while preserving the planar geometry advantageous to many applications. The molecular ordering of liquid crystal is variable with temperature and can be manipulated to form a layered thin film. In this way temperature and volume control can be used to vary film thickness in vacuo and on-demand between 10 nm and over 10 μm. These techniques were previously applied to a single-shot ion acceleration experiment in, where target thickness critically determines the physics of the acceleration. Here we present an automatic film formation device that utilizes a linear sliding rail to form liquid crystal films within the aforementioned range at rates up to 0.1 Hz. The design ensures film formation location within 2 μm RMS, well within the Rayleigh range of even short f-number systems. Details of liquid crystal films and this target formation device will be shown as well as recent experimental data from the Scarlet laser facility at OSU. This work was supported by DARPA through a grant from AMRDEC.

  3. Random lasing of microporous surface of Cr2+:ZnSe crystal induced by femtosecond laser

    NASA Astrophysics Data System (ADS)

    Yang, Xianheng; Feng, Guoying; Yao, Ke; Yi, Jiayu; Zhang, Hong; Zhou, Shouhuan

    2015-06-01

    We demonstrate a random lasing emission based on microporous surface of Cr2+:ZnSe crystal prepared by femtosecond pulsed laser ablation in high vacuum (below 5 × 10-4 Pa). The scanning electron microscope results show that there are a mass of micropores with an average size of ˜13 μm and smaller ones with ˜1.2 μm on the surface of Cr2+:ZnSe crystal. The adjacent micropore spacing of the smaller micropores ranges from 1 μm to 5 μm. Under 1750 nm excitation of Nd:YAG (355 nm) pumped optical parametric oscillator, a random lasing emission with center wavelength of 2350 nm and laser-like threshold of 0.3 mJ/pulse is observed. The emission lifetime of 2350 nm laser reduces from 800 ns to 30 ns as the pump energy increases above threshold. The emission spectra and decay time of smooth surface, groove and microporous surface of Cr2+:ZnSe crystal are contrasted. The optional pump wavelength range is from 1500 nm to 1950 nm, which in accordance with the optical absorption property of Cr2+:ZnSe crystal. The peak position of excitation spectra is almost identical to the strongest absorption wavelength.

  4. Laser characteristics of TGT-grown Nd,Y-codoped:SrF2 single crystal

    NASA Astrophysics Data System (ADS)

    Jelínek, Michal; Kubeček, Václav; Su, Liangbi; Jiang, Dapeng; Ma, Fengkai; Zhang, Qian; Cao, Yuexin; Xu, Jun

    2014-05-01

    In this contribution we present spectroscopic and laser properties of TGT (temperature gradient technique) grown Nd,Y:SrF2 crystals with neodymium concentration of 0.4, 0.65 and 0.8 at.%. The absorption cross-section, fluorescence spectra and fluorescence decay time were measured. For the laser experiments, the noncoated crystal samples 3.5 or 5 mm thick were pumped by a 796 nm laser diode matching the Nd:SrF2 absorption peak. Several output couplers with reflectivity ranging from 70 to 98 % at the generated wavelength were tested. In the pulsed pumping regime (pulseduration 2 ms, frequency 10 Hz), the maximum average output power of 75 mW was obtained with the slope efficiency as high as 48 % and the optical-to-optical efficiency of 42 % with respect to the absorbed pump power. The output beam spatial profile was nearly Gaussian in both axes, oscillations started at the wavelength of 1057 nm. At higher pumping levels, the second emission line at 1050 nm appears corresponding to our fluorescence measurements. Wavelength tuning using birefringent filter from 1048 to 1070 nm is probably given by crystal-field splitting of the 4F3/2 manifold in Nd3+. True-CW laser operation was also successfully obtained at lower pumping level with the maximum output power of 90 mW using output coupler reflectivity of 98 %.

  5. Nonlinear optical crystal optimized for ytterbium laser host wavelengths

    DOEpatents

    Ebbers, Christopher A.; Schaffers, Kathleen I.

    2007-08-21

    A material for harmonic generation has been made by substitutional changes to the crystal LaCa.sub.4(BO.sub.3).sub.3 also known as LaCOB in the form Re1.sub.xRe2.sub.yRe3.sub.zCa.sub.4(B0.sub.3).sub.3O where Re1 and Re2, (rare earth ion 1 and rare earth ion 2) are selected from the group consisting of Sc, Yttrium, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; Re3 is Lanthanum; and x+y+z=1.

  6. Nonlinear optical crystal optimized for Ytterbium laser host wavelengths

    DOEpatents

    Ebbers, Christopher A.; Schaffers, Kathleen I.

    2008-05-27

    A material for harmonic generation has been made by substitutional changes to the crystal LaCa.sub.4 (BO.sub.3).sub.3 also known as LaCOB in the form Re1.sub.xRe2.sub.yRe3.sub.zCa.sub.4(B0.sub.3).sub.3O where Re1 and Re2, (rare earth ion 1 and rare earth ion 2) are selected from the group consisting of Sc, Yttrium, La, Ce, Pr, Nd, Sm, Eu, Gd, Th, Dy, Ho, Er, Tm, Yb, and Lu; Re3 is Lanthanum; and x+y+z=1.

  7. Nonlinear optical crystal optimized for Ytterbium laser host wavelengths

    DOEpatents

    Ebbers, Christopher A.; Schaffers, Kathleen I.

    2007-02-20

    A material for harmonic generation has been made by substitutional changes to the crystal LaCa.sub.4 (BO.sub.3).sub.3 also known as LaCOB in the form Re1.sub.xRe2.sub.yRe3.sub.zCa.sub.4(BO.sub.3).sub.3O where Re1 and Re2, (rare earth ion 1 and rare earth ion 2) are selected from the group consisting of Sc, Yttrium, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu; Re3 is Lanthanum; and x+y+z=1.

  8. Growth, optical, thermal and laser damage threshold studies of 4-aminopyridinium 4-nitrophenolate 4-nitrophenol crystal

    NASA Astrophysics Data System (ADS)

    Jagadesan, A.; Peramaiyan, G.; Mohan Kumar, R.; Arjunan, S.

    2015-05-01

    Organic nonlinear optical (NLO) single crystals of 4-aminopyridinium 4-nitrophenolate 4-nitrophenol (4AP4NP) were grown by the slow evaporation solution growth technique. The unit cell parameters and space group of 4AP4NP crystal were found out by single crystal X-ray diffraction analysis. From the UV-vis-NIR spectral studies, the lower cut-off wavelength of the grown crystal was found to be 474 nm. The laser damage threshold study shows that 4AP4NP crystal withstands the laser radiation up to 3.67 GW cm-2. Thermogravimetric and differential thermal analyses revealed that 4AP4ANP is thermally stable up to 175 °C. The specific heat capacity of 4AP4NP was measured to be 3.9135 J g-1 K-1 at 33 °C. Kurtz and Perry powder study reveals that 4AP4NP is a phase-matchable NLO material. The four independent tensor coefficients of dielectric permittivity were found to be ε11=25.09, ε22=25.84, ε33=26.69 and ε13=0.8 from the dielectric measurement.

  9. Temporal, thermal, and light stability of continuously tunable cholesteric liquid crystal laser array.

    PubMed

    Jeong, Mi-Yun; Chung, Ki Soo; Wu, Jeong Weon

    2014-11-01

    Fine-structured polymerized cholesteric liquid crystal (PCLC) wedge laser devices have been realized, with high fine spatial tunability of the lasing wavelength. With resolution less than 0.3 nm in a broad spectral range, more than one hundred laser lines could be obtained in a PCLC cell without extra devices. For practical device application, we studied the stability of the device in detail over time, and in response to strong external light sources, and thermal perturbation. The PCLC wedge cells had good temporal stability for 1 year and showed good stability for strong perturbations, with the lasing wavelength shifting less than 1 nm, while the laser peak intensities decreased by up to 34%, and the high energy band edge of the photonic band gap (PBG) was red shifted 3 nm by temperature perturbation. However, when we consider the entire lasing spectrum for the PCLC cell, the 1-nm wavelength shift may not matter. Although the laser peak intensities were decreased by up to 34% in total for all of the perturbation cases, the remaining 34% laser peak intensity is considerable extent to make use. This good stability of the PCLC laser device is due to the polymerization of the CLC by UV curing. This study will be helpful for practical CLC laser device development.

  10. Studies on output characteristics of stable dual-wavelength ytterbium-doped photonic crystal fiber laser

    NASA Astrophysics Data System (ADS)

    Tian, Hongchun; Zhang, Sa; Hou, Zhiyun; Xia, Changming; Zhou, Guiyao; Zhang, Wei; Liu, Jiantao; Wu, Jiale; Fu, Jian

    2016-06-01

    A stable dual-wavelength ytterbium-doped photonic crystal fiber laser pumped by a 976 nm laser diode has been demonstrated at room temperature. Single-wavelength, dual-wavelength laser oscillations are observed when the fiber laser operates under different pump power by using different length of fibers. Stable dual-wavelength radiation around 1045 nm and 1075 nm has been generated simultaneously at a high pump power directly from an ytterbium-doped fiber laser without using any spectral control mechanism. A small core ytterbium-doped PCF fabricated by the powder sinter direction drawn rod technology is used as gain medium. The pump power and fiber length which can affect the output characteristics of dual-wavelength fiber laser are analyzed in the experiment. Experiments confirm that higher pump power and longer fiber length favors 1075 nm output; lower pump power and shorter fiber length favors 1045 nm output. Those results have a good reference in multi-wavelength fiber laser.

  11. Alexandrite laser frequency doubling in. beta. -BaB/sub 2/O/sub 4/ crystals

    SciTech Connect

    Chen, D.; Yeh, J.

    1988-10-01

    Efficient and tunable coherent ultraviolet (360--390 nm) generation in ..beta..-BaB/sub 2/O/sub 4/ crystals using type-I phase matching at room temperature is presented. The phase-matching angle is characterized with an alexandrite laser with a wavelength tuning range of 725--785 nm. The crystal angular bandwidth of 0.9 mrad-cm and spectral bandwidth of 1.15 nm-cm are also measured. UV output pulse energy of 105 mJ at 378 nm with 31% energy conversion efficiency is achieved.

  12. Self-optimization of optical confinement in an ultraviolet photonic crystal slab laser.

    PubMed

    Yamilov, A; Wu, X; Liu, X; Chang, R P H; Cao, H

    2006-03-01

    We studied numerically and experimentally the effects of structural disorder on the performance of ultraviolet photonic crystal slab lasers. Optical gain selectively amplifies the high-quality modes of the passive system. For these modes, the in-plane and out-of-plane leakage rates may be automatically balanced in the presence of disorder. The spontaneous optimization of in-plane and out-of-plane confinement of light in a photonic crystal slab may lead to a reduction of the lasing threshold.

  13. Ultra-flat supercontinuum generation in cascaded photonic crystal fiber with picosecond fiber laser pumping

    NASA Astrophysics Data System (ADS)

    Zhang, Huanian; Li, Ping

    2016-08-01

    In this letter, a new method for achieving ultra-flat supercontinuum generation is proposed. A picosecond fiber laser was used as the pump source, in a cascaded photonic crystal fiber, ultra-flat supercontinuum generation spectrum at 3 dB level from 1070 up to 1630 nm is obtained, to our knowledge, the 3 dB bandwidth of 560 nm is the most flat supercontinuum generation obtained in photonic crystal fibers, the results indicated that our method is efficient for achieving ultra-flat supercontinuum, which will promote the technical applications of supercontinuum.

  14. Melting of nanocrystals embedded in a crystal matrix heated by nanosecond laser pulses

    SciTech Connect

    Zinoviev, V. A. Dvurechenskii, A. V.; Smagina, Zh. V.; Ivlev, G. D.; Gatskevich, E. I.; Malevich, V. L.

    2012-09-15

    The kinetics of phase transformations of nanocrystals in a crystal matrix is considered upon non-stationary heating by laser pulses. The melting and crystallization kinetics of nanocrystals is described taking into account their size, shape, elemental composition, and elastic deformations appearing due to the mismatch of the lattice constants for nanocrystals and the matrix. The possibility of decreasing the dispersion of nanocrystals over their size in heterostructures with quantum dots is predicted. As an example, melting of Ge nanocrystals in a Si matrix is considered.

  15. Spectroscopic, thermal and cw dual-wavelength laser characteristics of Nd:LaF3 single crystal

    NASA Astrophysics Data System (ADS)

    Hong, Jiaqi; Zhang, Lianhan; Li, Jing; Wang, Zhaowei; He, Jingliang; Zhang, Peixiong; Wang, Yaqi; Hang, Yin

    2016-03-01

    A Nd-doped LaF3 crystal was grown by Czochralski method, and the rocking curves of (0 0 2) and (1 1 0) diffraction planes show good crystallinity quality of the as-grown crystal. Room-temperature fluorescence spectrum and transmittance spectrum of Nd:LaF3 crystal were investigated, both indicating probable dual-wavelength emissions at ∼1.04 μm and ∼1.06 μm. The thermal diffusivity and thermal conductivity of Nd:LaF3 crystal were detailed studied. Cw dual-wavelength laser operation of Nd:LaF3 single crystal at 1040 nm and around 1065 nm with LD pumping was demonstrated. A maximum output power of 302 mW was obtained with a slope efficiency of about 18.5% with respect to the pump power. The results of our study indicate the Nd:LaF3 crystal a promising laser crystal.

  16. Photonic crystal formation on optical nanofibers using femtosecond laser ablation technique.

    PubMed

    Nayak, K P; Hakuta, K

    2013-01-28

    We demonstrate that thousands of periodic nano-craters are fabricated on a subwavelength-diameter tapered optical fiber, an optical nanofiber, by irradiating with just a single femtosecond laser pulse. A key aspect of the fabrication is that the nanofiber itself acts as a cylindrical lens and focuses the femtosecond laser beam on its shadow surface. We also demonstrate that the periodic nano-crater array on the nanofiber shows polarization dependent fiber Bragg grating (FBG) characteristics. Such FBG structures on the nanofiber may act as a 1-D photonic crystal due to the strong transverse and longitudinal confinement of the field. PMID:23389229

  17. Optical channel waveguides in Nd:LGS laser crystals produced by proton implantation.

    PubMed

    Ren, Yingying; Tan, Yang; Chen, Feng; Jaque, Daniel; Zhang, Huaijin; Wang, Jiyang; Lu, Qingming

    2010-07-19

    Optical channel waveguides have been produced for the first time in Nd:LGS multi-functional laser crystals by using proton implantation. The obtained good guiding performance exhibits the well-confined modal fields in the waveguiding structures. The confocal fluorescence images of the obtained waveguides have revealed that the photoluminescence properties of the Nd(3+) ions have been well-preserved in the waveguide's active volume, which suggests promising applications as multi-functional integrated laser generation elements. These images have been also used to elucidate the spatial distribution of lattice damage and distortion caused by the implantation process, which are both mainly located at the nuclear collision region.

  18. Laser trapping of small colloidal particles in a nematic liquid crystal: clouds and ghosts.

    PubMed

    Musevic, I; Skarabot, M; Babic, D; Osterman, N; Poberaj, I; Nazarenko, V; Nych, A

    2004-10-29

    We show that, contrary to intuition, small (< or =1 microm) transparent particles can be trapped and manipulated in a nematic liquid crystal using an intense laser beam, although their index of refraction is lower than both refractive indices of the surrounding birefringent fluid. Two mechanisms are identified that are responsible for this anomalous trapping: (i) surface-induced distortion of the birefringent media around the particle, creating a high-index "cloud" around the colloid, and (ii) laser-induced distortion or (partial) melting of a nematic, creating a ghost colloid.

  19. Wavelength-controlled external-cavity laser with a silicon photonic crystal resonant reflector

    NASA Astrophysics Data System (ADS)

    Gonzalez-Fernandez, A. A.; Liles, Alexandros A.; Persheyev, Saydulla; Debnath, Kapil; O'Faolain, Liam

    2016-03-01

    We report the experimental demonstration of an alternative design of external-cavity hybrid lasers consisting of a III-V Semiconductor Optical Amplifier with fiber reflector and a Photonic Crystal (PhC) based resonant reflector on SOI. The Silicon reflector comprises a polymer (SU8) 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 sidemode suppression ratio of more than 25 dB.

  20. Analysis on the damage threshold of MgO:LiNbO3 crystals under multiple femtosecond laser pulses

    NASA Astrophysics Data System (ADS)

    Su, Zhuolin; Meng, Qinglong; Zhang, Bin

    2016-10-01

    An improved theoretical model of the interaction between multiple femtosecond laser pulses and MgO:LiNbO3 crystals with different doping concentrations has been established based on the classical two-temperature model. The evolutions of electron and lattice temperature with the duration, the repetition frequency and the numbers of multiple femtosecond laser pulses in MgO:LiNbO3 crystals have been simulated numerically by the Crank-Nicholson implicit finite-difference method. Furthermore, the variations of the damage threshold of MgO:LiNbO3 crystals with the parameters of multiple femtosecond laser pulses at different doping concentrations, as well as the influence of doping concentration on damage threshold have also been analyzed. The results show that, the damage threshold of MgO:LiNbO3 crystals increases with the increasing of the duration of the femtosecond laser pulse. The damage threshold of MgO:LiNbO3 crystals first decreases with the increasing of the numbers and the pulse repetition frequency of the laser pulses and then tends to be a constant. The damage threshold of a small amount of MgO-doped LiNbO3 crystals is higher than that of undoped LiNbO3 crystals. Consequently, the resist damage capability of LiNbO3 crystals can be enhanced by doping appropriate MgO in many practical applications.

  1. Investigation of factors affecting the synthesis of nano-cadmium sulfide by pulsed laser ablation in liquid environment

    NASA Astrophysics Data System (ADS)

    Darwish, Ayman M.; Eisa, Wael H.; Shabaka, Ali A.; Talaat, Mohamed H.

    2016-01-01

    Pulsed laser ablation in a liquid medium is a promising technique as compared to the other synthetic methods to synthesize different materials in nanoscale form. The laser parameters (e.g., wavelength, pulse width, fluence, and repetition frequency) and liquid medium (e.g., aqueous/nonaqueous liquid or solution with surfactant) were tightly controlled during and after the ablation process. By optimizing these parameters, the particle size and distribution of materials can be adjusted. The UV-vis absorption spectra and weight changes of targets were used for the characterization and comparison of products.

  2. Lifetime analysis of laser crystallized silicon films on glass

    SciTech Connect

    Kühnapfel, Sven; Amkreutz, Daniel; Gall, Stefan; Huang, Jialiang; Teal, Anthony; Kampwerth, Henner; Varlamov, Sergey

    2015-08-07

    Only recently, the quality of liquid phase crystallized silicon directly on glass substrates made a huge leap towards the quality of multi-crystalline wafers with open circuit voltages well above 600 mV. In this paper, we investigate the material quality in order to identify the factors limiting further performance improvements. We employ photoluminescence imaging on a state of the art test structure with lifetime calibration by transient photoluminescence. The resulting lifetime map is converted into an effective diffusion length map and the origin of regions with short lifetimes is investigated with electron backscattering and transmission electron microscopy. High local dislocation densities in areas with dissociated coincidence site lattice boundaries were found to be responsible for the localised quenching of the photoluminescence signal.

  3. Chemical Bonding in Sulfide Minerals

    SciTech Connect

    Vaughan, David J.; Rosso, Kevin M.

    2006-08-01

    An understanding of chemical bonding and electronic structure in sulfide minerals is central to any attempt at understanding their crystal structures, stabilities and physical properties. It is also an essential precursor to understanding reactivity through modeling surface structure at the molecular scale. In recent decades, there have been remarkable advances in first principles (ab initio) methods for the quantitative calculation of electronic structure. These advances have been made possible by the very rapid development of high performance computers. Several review volumes that chart the applications of these developments in mineralogy and geochemistry are available (Tossell and Vaughan, 1992; Cygan and Kubicki, 2001). An important feature of the sulfide minerals is the diversity of their electronic structures, as evidenced by their electrical and magnetic properties (see Pearce et al. 2006, this volume). Thus, sulfide minerals range from insulators through semiconductors to metals, and exhibit every type of magnetic behavior. This has presented problems for those attempting to develop bonding models for sulfides, and also led to certain misconceptions regarding the kinds of models that may be appropriate. In this chapter, chemical bonding and electronic structure models for sulfides are reviewed with emphasis on more recent developments. Although the fully ab initio quantitative methods are now capable of a remarkable degree of sophistication in terms of agreement with experiment and potential to interpret and predict behavior with varying conditions, both qualitative and more simplistic quantitative approaches will also be briefly discussed. This is because we believe that the insights which they provide are still helpful to those studying sulfide minerals. In addition to the application of electronic structure models and calculations to solid sulfides, work on sulfide mineral surfaces (Rosso and Vaughan 2006a,b) and solution complexes and clusters (Rickard

  4. Microwave emission by nonlinear crystals irradiated with a high-intensity, mode-locked laser

    NASA Astrophysics Data System (ADS)

    Borghesani, A. F.; Braggio, C.; Guarise, M.

    2016-06-01

    We report on the experimental investigation of the efficiency of some nonlinear crystals to generate microwave (RF) radiation as a result of optical rectification (OR) when irradiated with intense pulse trains delivered by a mode-locked laser at 1064 nm. We have investigated lithium triborate (LBO), lithium niobate (LiNbO3), zinc selenide (ZnSe), and also potassium titanyl orthophosphate (KTP) for comparison with previous measurements. The results are in good agreement with the theoretical predictions based on the form of the second-order nonlinear susceptibility tensor. For some crystals we investigated also the second harmonic generation (SHG) to cross check the theoretical model. We confirm the theoretical prediction that OR leads to the production of higher order RF harmonics that are overtones of the laser repetition rate.

  5. Loop Mirror Laser Neural Network with a Fast Liquid-Crystal Display

    NASA Astrophysics Data System (ADS)

    Mos, Evert C.; Schleipen, Jean J. H. B.; de Waardt, Huug; Khoe, Djan G. D.

    1999-07-01

    In our laser neural network (LNN) all-optical threshold action is obtained by application of controlled optical feedback to a laser diode. Here an extended experimental LNN is presented with as many as 32 neurons and 12 inputs. In the setup we use a fast liquid-crystal display to implement an optical matrix vector multiplier. This display, based on ferroelectric liquid-crystal material, enables us to present 125 training examples s to the LNN. To maximize the optical feedback efficiency of the setup, a loop mirror is introduced. We use a -rule learning algorithm to train the network to perform a number of functions toward the application area of telecommunication data switching.

  6. Anisotropic laser properties of Yb:Ca3La2(BO3)4 disordered crystal

    NASA Astrophysics Data System (ADS)

    Wang, Lisha; Xu, Honghao; Pan, Zhongben; Han, Wenjuan; Chen, Xiaowen; Liu, Junhai; Yu, Haohai; Zhang, Huaijin

    2016-08-01

    A study is carried out experimentally on the anisotropy in the laser action of Yb:Ca3La2(BO3)4 disordered crystal, demonstrated with the output coupling changed over a wide range from 0.5% to 40%. Complex polarization state variation with output coupling and evolution with pump power are observed in the laser operation achieved with a- and c-cut crystal samples. A maximum output power of 8.2 W is produced at wavelengths around 1043 nm, with an incident pump power of 24.9 W, the optical-to-optical efficiency being 33%. The polarized absorption and emission cross section spectra are also presented.

  7. Formation Mechanism of Titanium Carbide Crystal in Laser Synthesized Metal-Ceramic Composite Coating

    NASA Astrophysics Data System (ADS)

    Du, Baoshuai; Zhang, Zhongwen; Wang, Xinhong; Zou, Zengda

    In situ titanium carbide reinforced iron-based composite coating was deposited on mild carbon steel using laser surface engineering (LSE) with ferrotitanium and graphite as precursor. The microstructure and phase constituents of the deposited coating were characterized. Formation mechanism of titanium carbide crystal in the composite coating was elucidated by correlating the morphology of titanium carbide and the thermal cycle experienced by the precursor during the laser treatment. It was demonstrated that titanium carbide was formed in situ as a result of the metallurgical reaction between ferrotitanium and graphite following a liquid-precipitation route. Different morphologies of titanium carbide crystal (dendrite and fishbone) correspond to the primary and eutectic titanium carbide respectively.

  8. Matrix-assisted laser ablation production of gold cluster ions from Au-coated photonic crystals.

    PubMed

    Li, Jincheng; Liu, Jian'an; Chen, Yi

    2012-05-01

    A new strategy was explored to generate pure gold cluster ions, Au(n)(+/-), from gold films deposited on solid substrates via a matrix-assisted laser ablation technique. The gold films deposited on SiO(2)-particle-assembled photonic crystals were demonstrated to be the most ideal compared with the films deposited on various glass slides. Dropped with a matrix of 2-(4-hydroxyphenylazo) benzoic acid and bombarded by nitrogen pulse laser (355 nm), they could release a series of Au(n)(+) with n more than 110 or Au(n)(-) with n more than 60 according to the data obtained by inline time-of-flight mass spectrometry. The gold-deposited photonic crystal substrates could be stored at room temperature for at least 6 months. The method is hence steady and convenient in use. PMID:22576875

  9. Use of hollow core fibers, fiber lasers, and photonic crystal fibers for spark delivery and laser ignition in gases

    SciTech Connect

    Joshi, Sachin; Yalin, Azer P.; Galvanauskas, Almantas

    2007-07-01

    The fiber-optic delivery of sparks in gases is challenging as the output beam must be refocused to high intensity ({approx}200 GW/cm2 for nanosecond pulses). Analysis suggests the use of coated hollow core fibers, fiber lasers, and photonic crystal fibers (PCFs). We study the effects of launch conditions and bending for 2 m long coated hollow fibers and find an optimum launch f of {approx}55 allowing spark formation with {approx}98% reliability for bends up to a radius of curvature of 1.5 m in atmospheric pressure air. Spark formation using the output of a pulsed fiber laser is described, and delivery of 0.55 mJ pulses through PCFs is shown.

  10. Spectroscopic and laser properties of SrMoO4:Tm3+ crystal under 1700-nm laser diode pumping

    NASA Astrophysics Data System (ADS)

    Doroshenko, M. E.; Papashvili, A. G.; Dunaeva, E. E.; Ivleva, L. I.; Osiko, V. V.; Jelinkova, H.; Sulc, J.; Nemec, M.

    2016-10-01

    Spectroscopic and laser properties of Tm3+ ions under 1700 nm excitation in SrMoO4 crystal are investigated. Negligible effect of cross-relaxation process (3H4sbnd 3F4, 3H6sbnd 3F4) on population of 3F4 level for thulium concentrations up to 0.25 at.% was demonstrated. Efficient lasing with slope efficiency up to 18% and broadband (over 100 nm) tuning at room temperature under 1700 nm diode pumping were obtained.

  11. High brightness photonic band crystal semiconductor lasers in the passive mode locking regime

    SciTech Connect

    Rosales, R.; Kalosha, V. P.; Miah, M. J.; Bimberg, D.; Posilović, K.; Pohl, J.; Weyers, M.

    2014-10-20

    High brightness photonic band crystal lasers in the passive mode locking regime are presented. Optical pulses with peak power of 3 W and peak brightness of about 180 MW cm{sup −2} sr{sup −1} are obtained on a 5 GHz device exhibiting 15 ps pulses and a very low beam divergence in both the vertical and horizontal directions.

  12. Valence state change and defect centers induced by infrared femtosecond laser in Yb:YAG crystals

    SciTech Connect

    Wang, Xinshun Liu, Yang; Zhao, Panjuan; Guo, Zhongyi; Li, Yan; Qu, Shiliang

    2015-04-21

    The broad band upconversion luminescence in Yb{sup 3+}:YAG crystal has been observed in experiments under the irradiation of focused infrared femtosecond laser. The dependence of the fluorescence intensity on the pump power shows that the upconversion luminescence is due to simultaneous two-photon absorption process, which indicates that the broad emission bands at 365 and 463 nm could be assigned to the 5d → 4f transitions of Yb{sup 2+} ions and the one at 692 nm could be attributed to the electron-hole recombination process on (Yb{sup 2+}-F{sup +}) centers. The absorption spectra of the Yb:YAG crystal samples before and after femtosecond laser irradiation, and after further annealing reveal that permanent valence state change of Yb ions from Yb{sup 3+} to Yb{sup 2+} and (Yb{sup 2+}-F{sup +}) centers have been induced by infrared femtosecond laser irradiation in Yb{sup 3+}:YAG crystal.

  13. Spectroscopic and laser characterization of Yb,Tm:KLu(WO4)2 crystal

    NASA Astrophysics Data System (ADS)

    Loiko, P. A.; Serres, J. M.; Mateos, X.; Demesh, M. P.; Yasukevich, A. S.; Yumashev, K. V.; Petrov, V.; Griebner, U.; Aguiló, M.; Díaz, F.

    2016-01-01

    We report on a comprehensive spectroscopic and laser characterization of monoclinic Yb,Tm:KLu(WO4)2 crystals. Stimulated-emission cross-section spectra corresponding to the 3F4 → 3H6 transition of Tm3+ ions are determined. The radiative lifetime of the 3F4 state of Tm3+ ions is 0.82 ms. The maximum Yb3+ → Tm3+ energy transfer efficiency is 83.9% for 5 at.% Yb - 8 at.% Tm doping. The fractional heat loading for Yb,Tm:KLu(WO4)2 is 0.45 ± 0.05. Using a hemispherical cavity and 5 at.% Yb - 6 at.% Tm doped crystal, a maximum CW power of 227 mW is achieved at 1.983-2.011 μm with a maximum slope efficiency η = 14%. In the microchip laser set-up, the highest slope efficiency is 20% for a 5 at.% Yb- 8 at.% Tm doped crystal with a maximum output power of 201 mW at 1.99-2.007 μm. Operation of Yb,Tm:KLu(WO4)2 as a vibronic laser emitting at 2.081-2.093 μm is also demonstrated.

  14. Batch crystallization of rhodopsin for structural dynamics using an X-ray free-electron laser.

    PubMed

    Wu, Wenting; Nogly, Przemyslaw; Rheinberger, Jan; Kick, Leonhard M; Gati, Cornelius; Nelson, Garrett; Deupi, Xavier; Standfuss, Jörg; Schertler, Gebhard; Panneels, Valérie

    2015-07-01

    Rhodopsin is a membrane protein from the G protein-coupled receptor family. Together with its ligand retinal, it forms the visual pigment responsible for night vision. In order to perform ultrafast dynamics studies, a time-resolved serial femtosecond crystallography method is required owing to the nonreversible activation of rhodopsin. In such an approach, microcrystals in suspension are delivered into the X-ray pulses of an X-ray free-electron laser (XFEL) after a precise photoactivation delay. Here, a millilitre batch production of high-density microcrystals was developed by four methodical conversion steps starting from known vapour-diffusion crystallization protocols: (i) screening the low-salt crystallization conditions preferred for serial crystallography by vapour diffusion, (ii) optimization of batch crystallization, (iii) testing the crystal size and quality using second-harmonic generation (SHG) imaging and X-ray powder diffraction and (iv) production of millilitres of rhodopsin crystal suspension in batches for serial crystallography tests; these crystals diffracted at an XFEL at the Linac Coherent Light Source using a liquid-jet setup. PMID:26144230

  15. Batch crystallization of rhodopsin for structural dynamics using an X-ray free-electron laser.

    PubMed

    Wu, Wenting; Nogly, Przemyslaw; Rheinberger, Jan; Kick, Leonhard M; Gati, Cornelius; Nelson, Garrett; Deupi, Xavier; Standfuss, Jörg; Schertler, Gebhard; Panneels, Valérie

    2015-07-01

    Rhodopsin is a membrane protein from the G protein-coupled receptor family. Together with its ligand retinal, it forms the visual pigment responsible for night vision. In order to perform ultrafast dynamics studies, a time-resolved serial femtosecond crystallography method is required owing to the nonreversible activation of rhodopsin. In such an approach, microcrystals in suspension are delivered into the X-ray pulses of an X-ray free-electron laser (XFEL) after a precise photoactivation delay. Here, a millilitre batch production of high-density microcrystals was developed by four methodical conversion steps starting from known vapour-diffusion crystallization protocols: (i) screening the low-salt crystallization conditions preferred for serial crystallography by vapour diffusion, (ii) optimization of batch crystallization, (iii) testing the crystal size and quality using second-harmonic generation (SHG) imaging and X-ray powder diffraction and (iv) production of millilitres of rhodopsin crystal suspension in batches for serial crystallography tests; these crystals diffracted at an XFEL at the Linac Coherent Light Source using a liquid-jet setup.

  16. Investigations on the growth, optical, thermal, dielectric, and laser damage threshold properties of crystal violet dye-doped potassium acid phthalate single crystal

    NASA Astrophysics Data System (ADS)

    Rao, G. Babu; Rajesh, P.; Ramasamy, P.

    2016-03-01

    Influence of crystal violet dye with different concentration on potassium acid phthalate single crystal grown by conventional method has been studied. No change has been observed in the structure, whereas changes have been observed in the external morphology of the crystal when the dyes are incorporated in the crystal lattice. Thermogravimetric and differential thermal analyses show the onset decomposition temperatures to be at 302, 285, 284, and 285 °C for pure, 0.1, 0.3, and 0.5 mol% crystal violet-doped potassium acid phthalate crystals, respectively. The dielectric measurement was carried out on the grown crystals as a function of frequency at various temperatures. In addition, strong luminescent emission bands at 638, 648, and 640 nm were observed in which the relative intensity was found to be reversed as a result of doping concentration. The laser damage threshold value significantly increased for dye-doped crystal in comparison with pure crystal which may make it suitable for the solid-state dye laser applications.

  17. New criteria to choose the best Yb3+-doped laser crystals

    NASA Astrophysics Data System (ADS)

    Brenier, A.; Boulon, G.

    2001-09-01

    Using a model for the quasi-three-level laser dealing with Gaussian waves, taking into account the saturation of the pump, the stimulated emission at the pump wavelength, the variation of the pump and laser waists along propagation (important for laser diode pumping) and the variation of the laser intensity along propagation, we evaluate the more promising Yb3+-doped crystals for laser applications: YAG, LNB, GdCOB, YCOB, YAB, C-FAP, S-FAP, CLYPA, KGdW, KYW, Sc2O3, Y2O3, Lu2O3. Our evaluation, established for the CW oscillator regime, differs from that of Deloach and coworkers valid for ns pulse extraction mode. KYW, KGdW and Sc2O3 are found to be the most efficient when considering the laser extracted power and S-FAP, C-FAP, YAG, KYW and KGdW are the most efficient when considering the small-signal gain of the amplifier regime.

  18. Laser annealing induced ferromagnetism in SrTiO3 single crystal

    NASA Astrophysics Data System (ADS)

    Rao, S. S.; Lee, Y. F.; Prater, J. T.; Smirnov, A. I.; Narayan, J.

    2014-07-01

    The appearance of ferromagnetic order up to 400 K upon KrF (248 nm) laser irradiation is reported in un-doped SrTiO3 (STO) single crystal. The high resolution x-ray photo emission spectroscopy (XPS) measurements reveal a strong shift of Sr-, Ti-, and O-related peaks. X-ray diffraction of laser annealed STO does not reveal a signature of either secondary magnetic or amorphous phases. 300 K X-band (˜9.543 GHz) angle-dependent electron paramagnetic resonance (EPR) measurements showed no evidence of additional magnetic peaks upon laser irradiation. XPS and EPR data did not provide a strong evidence of Ti3+ formation upon laser annealing. No differences in the visible 300 K Raman spectra of pristine and laser annealed STO are noticed. Interestingly, the magnetic moment is decreased by almost 10-fold upon oxygen annealing of laser annealed STO, inferring that oxygen vacancies play an important role in establishing the observed ferromagnetism.

  19. Laser annealing induced ferromagnetism in SrTiO{sub 3} single crystal

    SciTech Connect

    Rao, S. S. Prater, J. T.; Lee, Y. F.; Narayan, J.; Smirnov, A. I.

    2014-07-28

    The appearance of ferromagnetic order up to 400 K upon KrF (248 nm) laser irradiation is reported in un-doped SrTiO{sub 3} (STO) single crystal. The high resolution x-ray photo emission spectroscopy (XPS) measurements reveal a strong shift of Sr-, Ti-, and O-related peaks. X-ray diffraction of laser annealed STO does not reveal a signature of either secondary magnetic or amorphous phases. 300 K X-band (∼9.543 GHz) angle-dependent electron paramagnetic resonance (EPR) measurements showed no evidence of additional magnetic peaks upon laser irradiation. XPS and EPR data did not provide a strong evidence of Ti{sup 3+} formation upon laser annealing. No differences in the visible 300 K Raman spectra of pristine and laser annealed STO are noticed. Interestingly, the magnetic moment is decreased by almost 10-fold upon oxygen annealing of laser annealed STO, inferring that oxygen vacancies play an important role in establishing the observed ferromagnetism.

  20. Backscatter laser depolarization studies of simulated stratospheric aerosols - Crystallized sulfuric acid droplets

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth; Zhao, Hongjie; Yu, Bing-Kun

    1989-01-01

    The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 micrometer) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of beta equivalent to 0.02, but beta equivalent to 0.10 to 0.15 are generated from aged acid cloud aerosols and acid droplet crystalization effects following the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar beta equivalent to 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (beta equivalent to 0) or ice crystal (beta equivalent to 0.5) clouds.

  1. Backscatter laser depolarization studies of simulated stratospheric aerosols: crystallized sulfuric acid droplets.

    PubMed

    Sassen, K; Zhao, H; Yu, B K

    1989-08-01

    The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 microm) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of delta approximately 0.02, but delta approximately 0.10-0.15 are generated from acid droplet crystallization effects associated with recycled aerosols and the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar delta approximately 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (delta approximately 0) or ice crystal (delta approximately 0.5) clouds.

  2. Backscatter laser depolarization studies of simulated stratospheric aerosols: Crystallized sulfuric acid droplets

    NASA Technical Reports Server (NTRS)

    Sassen, Kenneth; Zhao, Hongjie; Yu, Bing-Kun

    1988-01-01

    The optical depolarizing properties of simulated stratospheric aerosols were studied in laboratory laser (0.633 micrometer) backscattering experiments for application to polarization lidar observations. Clouds composed of sulfuric acid solution droplets, some treated with ammonia gas, were observed during evaporation. The results indicate that the formation of minute ammonium sulfate particles from the evaporation of acid droplets produces linear depolarization ratios of beta equivalent to 0.02, but beta equivalent to 0.10 to 0.15 are generated from aged acid cloud aerosols and acid droplet crystallization effects following the introduction of ammonia gas into the chamber. It is concluded that partially crystallized sulfuric acid droplets are a likely candidate for explaining the lidar beta equivalent to 0.10 values that have been observed in the lower stratosphere in the absence of the relatively strong backscattering from homogeneous sulfuric acid droplet (beta equivalent to 0) or ice crystal (beta equivalent to 0.5) clouds.

  3. Iron isotope composition of particles produced by UV-femtosecond laser ablation of natural oxides, sulfides, and carbonates.

    PubMed

    d'Abzac, Francois-Xavier; Beard, Brian L; Czaja, Andrew D; Konishi, Hiromi; Schauer, James J; Johnson, Clark M

    2013-12-17

    The need for femtosecond laser ablation (fs-LA) systems coupled to MC-ICP-MS to accurately perform in situ stable isotope analyses remains an open question, because of the lack of knowledge concerning ablation-related isotopic fractionation in this regime. We report the first iron isotope analysis of size-resolved, laser-induced particles of natural magnetite, siderite, pyrrhotite, and pyrite, collected through cascade impaction, followed by analysis by solution nebulization MC-ICP-MS, as well as imaging using electron microscopy. Iron mass distributions are independent of mineralogy, and particle morphology includes both spheres and agglomerates for all ablated phases. X-ray spectroscopy shows elemental fractionation in siderite (C-rich agglomerates) and pyrrhotite/pyrite (S-rich spheres). We find an increase in (56)Fe/(54)Fe ratios of +2‰, +1.2‰, and +0.8‰ with increasing particle size for magnetite, siderite, and pyrrhotite, respectively. Fe isotope differences in size-sorted aerosols from pyrite ablation are not analytically resolvable. Experimental data are discussed using models of particles generation by Hergenröder and elemental/isotopic fractionation by Richter. We interpret the isotopic fractionation to be related to the iron condensation time scale, dependent on its saturation in the gas phase, as a function of mineral composition. Despite the isotopic variations across aerosol size fractions, total aerosol composition, as calculated from mass balance, confirms that fs-LA produces a stoichiometric sampling in terms of isotopic composition. Specifically, both elemental and isotopic fractionation are produced by particle generation processes and not by femtosecond laser-matter interactions. These results provide critical insights into the analytical requirements for laser-ablation-based stable isotope measurements of high-precision and accuracy in geological samples, including the importance of quantitative aerosol transport to the ICP. PMID

  4. Single-crystal Brillouin spectroscopy with CO{sub 2} laser heating and variable q

    SciTech Connect

    Zhang, Jin S.; Bass, Jay D.; Zhu, Gaohua

    2015-06-15

    We describe a Brillouin spectroscopy system integrated with CO{sub 2} laser-heating and Raman spectroscopic capabilities. Temperature is determined by measurements of the grey-body thermal radiation emitted by the hot sample, with the system response calibrated relative to a standard tungsten ribbon lamp. High-pressure laser-heating Brillouin scattering measurements of acoustic velocities on liquid water and ice compressed in a diamond-anvil cell were performed at temperatures up to 2500 ± 150 K at high pressure. Single-crystal laser-heating Brillouin measurements were made on the (111) plane of San Carlos olivine at ∼13 GPa, 1300 ± 200 K. The pressure as measured by ruby fluorescence is shown to be within ±0.5 GPa of the pressure on the olivine sample during laser heating when KCl and KBr are used as pressure-transmitting media. In addition, the system is designed for continuously variable scattering angles from forward scattering (near 0° scattering angle) up to near back scattering (∼141°). This novel setup allows us to probe a wide range of wave vectors q for investigation of phonon dispersion on, for example, crystals with large unit cells (on the scale of hundreds of nm)

  5. Single-crystal Brillouin spectroscopy with CO2 laser heating and variable q

    NASA Astrophysics Data System (ADS)

    Zhang, Jin S.; Bass, Jay D.; Zhu, Gaohua

    2015-06-01

    We describe a Brillouin spectroscopy system integrated with CO2 laser-heating and Raman spectroscopic capabilities. Temperature is determined by measurements of the grey-body thermal radiation emitted by the hot sample, with the system response calibrated relative to a standard tungsten ribbon lamp. High-pressure laser-heating Brillouin scattering measurements of acoustic velocities on liquid water and ice compressed in a diamond-anvil cell were performed at temperatures up to 2500 ± 150 K at high pressure. Single-crystal laser-heating Brillouin measurements were made on the (111) plane of San Carlos olivine at ˜13 GPa, 1300 ± 200 K. The pressure as measured by ruby fluorescence is shown to be within ±0.5 GPa of the pressure on the olivine sample during laser heating when KCl and KBr are used as pressure-transmitting media. In addition, the system is designed for continuously variable scattering angles from forward scattering (near 0° scattering angle) up to near back scattering (˜141°). This novel setup allows us to probe a wide range of wave vectors q for investigation of phonon dispersion on, for example, crystals with large unit cells (on the scale of hundreds of nm).

  6. A Photonic Crystal Laser from Solution Based Organo-Lead Iodide Perovskite Thin Films.

    PubMed

    Chen, Songtao; Roh, Kwangdong; Lee, Joonhee; Chong, Wee Kiang; Lu, Yao; Mathews, Nripan; Sum, Tze Chien; Nurmikko, Arto

    2016-04-26

    Perovskite semiconductors are actively investigated for high performance solar cells. Their large optical absorption coefficient and facile solution-based, low-temperature synthesis of thin films make perovskites also a candidate for light-emitting devices across the visible and near-infrared. Specific to their potential as optical gain medium for lasers, early work has demonstrated amplified spontaneous emission and lasing at attractively low thresholds of photoexcitation. Here, we take an important step toward practically usable perovskite lasers where a solution-processed thin film is embedded within a two-dimensional photonic crystal resonator. We demonstrate high degree of temporally and spatially coherent lasing whereby well-defined directional emission is achieved near 788 nm wavelength at optical pumping energy density threshold of 68.5 ± 3.0 μJ/cm(2). The measured power conversion efficiency and differential quantum efficiency of the perovskite photonic crystal laser are 13.8 ± 0.8% and 35.8 ± 5.4%, respectively. Importantly, our approach enables scalability of the thin film lasers to a two-dimensional multielement pixelated array of microlasers which we demonstrate as a proof-of-concept for possible projection display applications. PMID:26997122

  7. The effect of multiple wavelengths on Laser-induced damage in DKDP crystals

    SciTech Connect

    Carr, C W; Auerbach, J M

    2005-07-11

    Laser-induced damage is a key factor that constrains how optical materials are used in high-power laser systems. In this work the size and density of bulk laser-induced damage sites formed during frequency tripling in a DKDP crystal are studied. The characteristics of the damage sites formed during tripling, where 1053-nm, 526-nm, and 351-nm light is simultaneously present, are compared to damage sites formed by 351-nm light alone. The fluence of each wavelength is calculated as a function of depth with a full 4D(x,y,z,t) frequency conversion code and compared to measured damage density and size distributions. The density of damage is found be predominantly governed by 351-nm light with some lesser, though non-negligible contribution from 526-nm light. The morphology of the damage sites, however, is seen to be relatively insensitive to wavelength and depend only on total fluence of all wavelengths present.

  8. Cladding single crystal YAG fibers grown by laser heated pedestal growth

    NASA Astrophysics Data System (ADS)

    Bera, Subhabrata; Nie, Craig D.; Harrington, James A.; Chick, Theresa; Chakrabarty, Ayan; Trembath-Reichert, Stephen; Chapman, James; Rand, Stephen C.

    2016-03-01

    Rare-earth doped single-crystal (SC) Yttrium Aluminum Garnet (YAG) fibers are excellent candidates for high power lasers. These SC fiber optics combine the favorable low Stimulated Brillouin Scattering (SBS) gain coefficient and excellent thermal properties to make them an attractive alternative to glass fiber lasers and amplifiers. Various rare-earth doped SC fibers have been grown using the laser heated pedestal growth (LHPG) technique. Several cladding methods, including in-situ and post-growth cladding techniques, are discussed in this paper. A rod-in-tube approach has been used by to grow a fiber with an Erbium doped SC YAG fiber core inserted in a SC YAG tube. The result is a radial gradient in the distribution of rare-earth ions. Post cladding methods include sol-gel deposited polycrystalline.

  9. Properties of Cr:LiSrAlF[sub 6] crystals for laser operation

    SciTech Connect

    Chai, B.H.T. ); Payne, S.A.; Smith, L.K.; Beach, R.J.; Tassano, J.H.; DeLoach, L.D.; Kway, W.L.; Solarz, R.W.; Krupke, W.F. )

    1994-08-20

    We have performed several physical and optical measurements on the Cr:LiSAF (LiSrAlF[sub 6]) laser material that are relevant to its laser performance, including thermal and mechanical properties, water durabilities, and Auger upconversion constants. The expansion coefficient, Young's modulus, fracture toughness, thermal conductivity, and heat capacity are all used to determine an overall thermomechanical figure of merit for the crystal. An investigation of the water durability suggests that the cooling solution should be maintained at pH = 7 to ameliorate problems associated with water dissolution. The Auger constant was found to become much more significant at higher Cr doping, in which excited-state migration leads to a substantial increase in the upconversion rate. We propose a design for a 50-W Cr:LiSAF laser system that is based on a detailed knowledge of all the relevant material parameters.

  10. Rear surface spallation on single-crystal silicon in nanosecond laser micromachining

    NASA Astrophysics Data System (ADS)

    Ren, Jun; Orlov, Sergei S.; Hesselink, Lambertus

    2005-05-01

    Rear surface spallation of single-crystal silicon under 5-ns laser pulse ablation at intensities of 0.6-60GW/cm2 is studied through postablation examination of the ablated samples. The spallation threshold energy and the spallation depth's dependences on the energy and target thickness are measured. From the linear relation between the spallation threshold energy and the target thickness, an estimation of the material spall strength around 1.4GPa is obtained, in reasonable agreement with the spall strength estimation of 0.8-1.2GPa at a strain rate of 107s-1 using Grady's model for brittle materials. The experiment reveals the internal fracturing process over an extended zone in silicon, which is controlled by the competition between the shock pressure load and the laser ablation rate. The qualities of the laser microstructuring and micromachining results are greatly improved by using an acoustic impedance matching approach.

  11. Two-dimensional surface emitting photonic crystal laser with hybrid triangular-graphite structure.

    PubMed

    Martínez, Luis Javier; Alén, Benito; Prieto, Ivan; Galisteo-López, J F; Galli, Matteo; Andreani, Lucio Claudio; Seassal, Christian; Viktorovitch, Pierre; Postigo, Pablo Aitor

    2009-08-17

    We present laser emission of a compact surface-emitting micro laser, optical pumped and operating at 1.5 microm at room temperature. A two-dimensional photonic crystal lattice conformed in a hybrid triangular-graphite configuration is designed for vertical emission. The structures have been fabricated in an InP slab, including four InAsP quantum wells as active layer, on the top of a Si substrate SiO(2) wafer bonded. Laser emission with thresholds around 70 microW and quality factors (Qs) up to 12000 have been measured. The Bloch mode selected for the emission keeps a high Q (>or= 2 x 10(5)) around the Gamma point for a wide range of in-plane values k(||)

  12. Direct laser-writing of ferroelectric single-crystal waveguide architectures in glass for 3D integrated optics.

    PubMed

    Stone, Adam; Jain, Himanshu; Dierolf, Volkmar; Sakakura, Masaaki; Shimotsuma, Yasuhiko; Miura, Kiyotaka; Hirao, Kazuyuki; Lapointe, Jerome; Kashyap, Raman

    2015-01-01

    Direct three-dimensional laser writing of amorphous waveguides inside glass has been studied intensely as an attractive route for fabricating photonic integrated circuits. However, achieving essential nonlinear-optic functionality in such devices will also require the ability to create high-quality single-crystal waveguides. Femtosecond laser irradiation is capable of crystallizing glass in 3D, but producing optical-quality single-crystal structures suitable for waveguiding poses unique challenges that are unprecedented in the field of crystal growth. In this work, we use a high angular-resolution electron diffraction method to obtain the first conclusive confirmation that uniform single crystals can be grown inside glass by femtosecond laser writing under optimized conditions. We confirm waveguiding capability and present the first quantitative measurement of power transmission through a laser-written crystal-in-glass waveguide, yielding loss of 2.64 dB/cm at 1530 nm. We demonstrate uniformity of the crystal cross-section down the length of the waveguide and quantify its birefringence. Finally, as a proof-of-concept for patterning more complex device geometries, we demonstrate the use of dynamic phase modulation to grow symmetric crystal junctions with single-pass writing. PMID:25988599

  13. Direct laser-writing of ferroelectric single-crystal waveguide architectures in glass for 3D integrated optics

    PubMed Central

    Stone, Adam; Jain, Himanshu; Dierolf, Volkmar; Sakakura, Masaaki; Shimotsuma, Yasuhiko; Miura, Kiyotaka; Hirao, Kazuyuki; Lapointe, Jerome; Kashyap, Raman

    2015-01-01

    Direct three-dimensional laser writing of amorphous waveguides inside glass has been studied intensely as an attractive route for fabricating photonic integrated circuits. However, achieving essential nonlinear-optic functionality in such devices will also require the ability to create high-quality single-crystal waveguides. Femtosecond laser irradiation is capable of crystallizing glass in 3D, but producing optical-quality single-crystal structures suitable for waveguiding poses unique challenges that are unprecedented in the field of crystal growth. In this work, we use a high angular-resolution electron diffraction method to obtain the first conclusive confirmation that uniform single crystals can be grown inside glass by femtosecond laser writing under optimized conditions. We confirm waveguiding capability and present the first quantitative measurement of power transmission through a laser-written crystal-in-glass waveguide, yielding loss of 2.64 dB/cm at 1530 nm. We demonstrate uniformity of the crystal cross-section down the length of the waveguide and quantify its birefringence. Finally, as a proof-of-concept for patterning more complex device geometries, we demonstrate the use of dynamic phase modulation to grow symmetric crystal junctions with single-pass writing. PMID:25988599

  14. Transmission characteristics of high-power 589-nm laser beam in photonic crystal fiber

    NASA Astrophysics Data System (ADS)

    Ito, Meguru; Hayano, Yutaka; Saito, Norihito; Akagawa, Kazuyuki; Kato, Mayumi; Saito, Yoshihiko; Takazawa, Akira; Takami, Hideki; Iye, Masanori; Wada, Satoshi; Colley, Stephen A.; Dinkins, Matthew C.; Eldred, Michael; Golota, Taras I.; Guyon, Olivier; Hattori, Masayuki; Oya, Shin; Watanabe, Makoto

    2006-06-01

    We are developing Laser Guide Star Adaptive Optics (LGSAO) system for Subaru Telescope at Hawaii, Mauna Kea. We achieved an all-solid-state 589.159 nm laser in sum-frequency generation. Output power at 589.159 nm reached 4W in quasi-continuous-wave operation. To relay the laser beam from laser location to laser launching telescope, we used an optical fiber because the optical fiber relay is more flexible and easier than mirror train. However, nonlinear scattering effect, especially stimulated Raman scattering (SRS) and stimulated Brillouin scattering (SBS), will happen when the inputted laser power increases, i.e., intensity at the fiber core exceed each threshold. In order to raise the threshold levels of each nonlinear scattering, we adopt photonic crystal fiber (PCF). Because the PCF can be made larger core than usual step index fiber (SIF), one can reduce the intensity in the core. We inputted the high power laser into the PCF whose mode field diameter (MFD) is 14 μm and the SIF whose MFD is 5 μm, and measured the transmission characteristics of them. In the case of the SIF, the SRS was happen when we inputted 2 W. On the other hand, the SRS and the SBS were not induced in the PCF even for an input power of 4 W. We also investigated polarization of the laser beam transmitting through the PCF. Because of the fact that the backscattering efficiency of exciting the sodium layer with a narrowband laser is dependent on the polarization state of the incident beam, we tried to control the polarization of the laser beam transmitted the PCF. We constructed the system which can control the polarization of input laser and measure the output polarization. The PCF showed to be able to assume as a double refraction optical device, and we found that the output polarization is controllable by injecting beam with appropriate polarization through the PCF. However, the Laser Guide Star made by the beam passed through the PCF had same brightness as the state of the polarization.

  15. Ca 4REO(BO 3) 3 crystals for green and blue microchip laser generation: from crystal growth to laser and nonlinear optical properties

    NASA Astrophysics Data System (ADS)

    Aka, G.; Reino, E.; Loiseau, P.; Vivien, D.; Ferrand, B.; Fulbert, L.; Pelenc, D.; Lucas-Leclin, G.; Georges, Patrick

    2004-09-01

    We have taken advantage of congruent melting behavior of the nonlinear rare-earth oxoborate Ca 4REO(BO 3) 3 family to perfect a process of collective fabrication of self-frequency doubling microchip laser based on Nd:GdCOB (Ca 4Gd 1- xNd xO(BO 3) 3) crystals. The process goes from Czochralski boule to 1 × 3 mm 2 chips perfectly oriented (better than 0.1°) to the phase matching direction ( θ=90°, φ=46°) in the XY principal plane, with dielectric mirrors directly deposited on both faces of the chips. 20 mW of self-frequency doubling output power at 530 nm was performed under 800 mW of diode laser as incident pump power at 812 nm. In addition, new compositions from the solid solution Ca 4Gd 1- xY xO(BO 3) 3 (Gd 1- xY xCOB) ( x=0.13, 0.16, 0.44) have been grown by the Czochralski pulling method, in order to achieve noncritical phase matching (NCPM) second harmonic generation of 4F 3/2 → 4I 9/2 Nd 3+ doped laser hosts. Three types of laser wavelengths have been chosen: Nd:YAP (YAlO 3) at 930 nm, Nd:YAG (Y 3Al 5O 12) at 946 nm, and Nd:ASL (Nd ySr 1- x La x- yMg x Al 12- xO 19) at 900 nm. Angular acceptance measurements of these three types of compositions present very large values, compared to pure GdCOB or YCOB oriented in critical phase matching configurations.

  16. Fluorescence quantum efficiency and optical heating efficiency in laser crystals and glasses by laser calorimetry

    SciTech Connect

    Ramponi, A.J.; Caird, J.A.

    1988-06-01

    A photocaloric technique is described for determining the fluorescence quantum efficiencies and optical heating efficiencies of optically active ions in laser materials. Optical absorption within the sample results in a temperature increase until the heat produced by the absorbed power is balanced by heat leakage to the surroundings. The fluorescence quantum efficiency and optical heating efficiency are determined from a measure of the absorbed power, the steady-state temperature, and the time constant associated with sample cooling following laser excitation. An alternative analysis utilizing only the absorbed power and the steady-state temperature as a function of excitation frequency is also shown to yield quantum efficiencies consistent with the first method. Theory and experiment are demonstrated by measuring the fluorescence quantum efficiency and optical heating efficiency for trivalent chromium in gadolinium scandium gallium garnet. Measurements are also reported for several neodymium-doped phosphate laser glasses.

  17. Sulfur and sulfides in chondrules

    NASA Astrophysics Data System (ADS)

    Marrocchi, Yves; Libourel, Guy

    2013-10-01

    The nature and distribution of sulfides within type I PO, POP and PP chondrules of the carbonaceous chondrite Vigarano (CV3) have been studied by secondary electron microscopy and electron microprobe. They occur predominantly as spheroidal blebs composed entirely of low-Ni iron sulfide (troilite, FeS) or troilite + magnetite but in less abundance in association with metallic Fe-Ni beads in opaque assemblages. Troilites are mainly located within the low-Ca pyroxene outer zone and their amounts increase with the abundance of low-Ca pyroxene within chondrules, suggesting co-crystallization of troilite and low-Ca pyroxene during high-temperature events. We show that sulfur concentration and sulfide occurrence in chondrules obey high temperature sulfur solubility and saturation laws. Depending on the fS2 and fO2 of the surrounding gas and on the melt composition, mainly the FeO content, sulfur dissolved in chondrule melts may eventually reach a concentration limit, the sulfur content at sulfide saturation (SCSS), at which an immiscible iron sulfide liquid separates from the silicate melt. The occurrence of both a silicate melt and an immiscible iron sulfide liquid is further supported by the non-wetting behavior of sulfides on silicate phases in chondrules due to the high interfacial tension between their precursor iron-sulfide liquid droplets and the surrounding silicate melt during the high temperature chondrule-forming event. The evolution of chondrule melts from PO to PP towards more silicic compositions, very likely due to high PSiO(g) of the surrounding nebular gas, induces saturation of FeS at much lower S content in PP than in PO chondrules, leading to the co-crystallization of iron sulfides and low-Ca pyroxenes. Conditions of co-saturation of low-Ca pyroxene and FeS are only achieved in non canonical environments characterized by high partial pressures of sulfur and SiO and redox conditions more oxidizing than IW-3. Fe and S mass balance calculations also

  18. Preferential growth orientation of laser-patterned LiNbO{sub 3} crystals in lithium niobium silicate glass

    SciTech Connect

    Komatsu, T.; Koshiba, K.; Honma, T.

    2011-02-15

    Dots and lines consisting of LiNbO{sub 3} crystals are patterned on the surface of 1CuO-40Li{sub 2}O-32Nb{sub 2}O{sub 5}-28SiO{sub 2} (mole ratio) glass by irradiations of continuous-wave Nd:YAG laser (wavelength: {lambda}=1064 nm), diode laser ({lambda}=795 nm), and Yb:YVO{sub 4} fiber laser ({lambda}=1080 nm), and the feature of laser-patterned LiNbO{sub 3} crystal growth is examined from linearly polarized micro-Raman scattering spectrum measurements. LiNbO{sub 3} crystals with the c-axis orientation are formed at the edge parts of the surface and cross-section of dots. The growth direction of an LiNbO{sub 3} along the laser scanning direction is the c-axis. It is proposed that the profile of the temperature distribution in the laser-irradiated region and its change along laser scanning would be one of the most important conditions for the patterning of crystals with a preferential growth orientation. Laser irradiation giving a narrow width is also proposed to be one of the important factors for the patterning of LiNbO{sub 3} crystal lines with homogeneous surface morphologies. -- Graphical abstract: Polarized optical microscope observations for the surface and cross-section of the dot obtained by LD laser ({lambda}=795 nm) irradiations of P=1.4 W and t=20 s in Cu-LNS glass. Schematic model for the orientation of LiNbO{sub 3} crystals at the edge parts of the surface and cross-section of the dot is also shown. Display Omitted Research highlights: > Dots and lines with LiNbO{sub 3} crystals are patterned on the glass surface by laser irradiations. > LiNbO{sub 3} crystals with the c-axis orientation are formed at the edge parts of the surface and cross-section of dots. > The profile of the temperature distribution in the laser-irradiated region is one of the most important conditions for the patterning of highly oriented crystals.

  19. Growth of periodic ZnO nano-crystals on buffer layer patterned by interference laser irradiation

    NASA Astrophysics Data System (ADS)

    Nakamura, D.; Shimogaki, T.; Okazaki, K.; Higashihata, M.; Nakata, Y.; Okada, T.

    2013-03-01

    Zinc oxide (ZnO) nano-crystal is great interest for optoelectronic applications in particular ultraviolet (UV) region such as UV-LEDs, UV-lasers, etc. For the practical optoelectronic applications based on the ZnO nanocrystals, control of nanowire growth direction, shape, density, and position are essentially required. In our study, we introduced a ZnO buffer layer and interference laser irradiation to control the growth position of ZnO nanocrystals. In this presentation, structural and morphological characteristics of periodic ZnO nano-crystals synthesized by the nanoparticle-assisted pulsed laser deposition will be discussed.

  20. Room temperature continuous wave operation of InAs/GaAs quantum dot photonic crystal nanocavity laser on silicon substrate.

    PubMed

    Tanabe, Katsuaki; Nomura, Masahiro; Guimard, Denis; Iwamoto, Satoshi; Arakawa, Yasuhiko

    2009-04-27

    Room temperature, continuous-wave lasing in a quantum dot photonic crystal nanocavity on a Si substrate has been demonstrated by optical pumping. The laser was an air-bridge structure of a two-dimensional photonic crystal GaAs slab with InAs quantum dots inside on a Si substrate fabricated through wafer bonding and layer transfer. This surface-emitting laser exhibited emission at 1.3 microm with a threshold absorbed power of 2 microW, the lowest out of any type of lasers on silicon.

  1. Influence of crystal orientation on the formation of femtosecond laser-induced periodic surface structures and lattice defects accumulation

    SciTech Connect

    Sedao, Xxx; Garrelie, Florence Colombier, Jean-Philippe; Reynaud, Stéphanie; Pigeon, Florent; Maurice, Claire; Quey, Romain

    2014-04-28

    The influence of crystal orientation on the formation of femtosecond laser-induced periodic surface structures (LIPSS) has been investigated on a polycrystalline nickel sample. Electron Backscatter Diffraction characterization has been exploited to provide structural information within the laser spot on irradiated samples to determine the dependence of LIPSS formation and lattice defects (stacking faults, twins, dislocations) upon the crystal orientation. Significant differences are observed at low-to-medium number of laser pulses, outstandingly for (111)-oriented surface which favors lattice defects formation rather than LIPSS formation.

  2. Electrically controllable liquid crystal random lasers below the Fréedericksz transition threshold.

    PubMed

    Lee, Chia-Rong; Lin, Jia-De; Huang, Bo-Yuang; Lin, Shih-Hung; Mo, Ting-Shan; Huang, Shuan-Yu; Kuo, Chie-Tong; Yeh, Hui-Chen

    2011-01-31

    This investigation elucidates for the first time electrically controllable random lasers below the threshold voltage in dye-doped liquid crystal (DDLC) cells with and without adding an azo-dye. Experimental results show that the lasing intensities and the energy thresholds of the random lasers can be decreased and increased, respectively, by increasing the applied voltage below the Fréedericksz transition threshold. The below-threshold-electric-controllability of the random lasers is attributable to the effective decrease of the spatial fluctuation of the orientational order and thus of the dielectric tensor of LCs by increasing the electric-field-aligned order of LCs below the threshold, thereby increasing the diffusion constant and decreasing the scattering strength of the fluorescence photons in their recurrent multiple scattering. This can result in the decrease in the lasing intensity of the random lasers and the increase in their energy thresholds. Furthermore, the addition of an azo-dye in DDLC cell can induce the range of the working voltage below the threshold for the control of the random laser to reduce.

  3. Energy transfer between laser beams due to recording of optical axis gratings in liquid crystals

    NASA Astrophysics Data System (ADS)

    Nersisyan, Sarik R.; Tabiryan, Nelson V.; Stickley, C. Martin

    2006-10-01

    We have studied two-beam-coupling processes related to the generation of optical axis gratings in liquid crystals (LCs) due to the electromagnetic torque acting on the orientation of LCs in superimposed laser beams with spatially modulated polarization. Such gratings result in efficient coupling between the laser beams controlled by the frequency shift introduced between the beams at infrasound frequencies. Larger than 80% efficiency of energy transfer from a pump to a signal beam is reported at power density levels of the laser beams at 1-10 kW/cm2. The distinction between pump and signal beams is relative, since the sign of the frequency shift rather than the power ratio between the beams determines the direction of energy transfer. The experiments were performed for radiation at a 1.06 μm wavelength; high optical nonlinearity and low absorption make LCs suitable for use in visible and near-IR spectra, particularly in high-power laser systems. We have characterized the main fundamental features of the process of recording dynamic orientation gratings, plotting the gain spectra for several LCs and verifying the good quality of the amplified signal beam even for a strongly distorted pump. The obtained results set the groundwork for a variety of novel opportunities and applications that include combining high-power laser beams and wavelength division multiplexing at an ultranarrow interval of frequencies of the order of 1-100 Hz.

  4. Effect of deposition temperature on electron-beam evaporated polycrystalline silicon thin-film and crystallized by diode laser

    SciTech Connect

    Yun, J. Varalmov, S.; Huang, J.; Green, M. A.; Kim, K.

    2014-06-16

    The effects of the deposition temperature on the microstructure, crystallographic orientation, and electrical properties of a 10-μm thick evaporated Si thin-film deposited on glass and crystallized using a diode laser, are investigated. The crystallization of the Si thin-film is initiated at a deposition temperature between 450 and 550 °C, and the predominant (110) orientation in the normal direction is found. Pole figure maps confirm that all films have a fiber texture and that it becomes stronger with increasing deposition temperature. Diode laser crystallization is performed, resulting in the formation of lateral grains along the laser scan direction. The laser power required to form lateral grains is higher in case of films deposited below 450 °C for all scan speeds. Pole figure maps show 75% occupancies of the (110) orientation in the normal direction when the laser crystallized film is deposited above 550 °C. A higher density of grain boundaries is obtained when the laser crystallized film is deposited below 450 °C, which limits the solar cell performance by n = 2 recombination, and a performance degradation is expected due to severe shunting.

  5. High-resolution X-ray focusing concave (elliptical) curved crystal spectrograph for laser-produced plasma

    NASA Astrophysics Data System (ADS)

    Xiao, Shali; Pan, Yingjun; Zhong, Xianxin; Xiong, Xiancai; Yang, Guohong; Liu, Zongli; Ding, Yongkun

    2004-08-01

    The X-ray spectrum emitted from laser-produced plasma contains plentiful information. X-ray spectrometer is a powerful tool for plasma diagnosis and studying the information and evolution of the plasma. X-ray concave (elliptical) curved crystals analyzer was designed and manufactured to investigate the properties of laser-produced plasma. The experiment was carried out on Mianyang Xingguang-II Facility and aimed at investigating the characteristics of a high density iron plasma. Experimental results using KAP, LIF, PET, and MICA curved crystal analyzers are described, and the spectra of Au, Ti laser-produced plasma are shown. The focusing crystal analyzer clearly gave an increase in sensitivity over a flat crystal.

  6. A Nd:MgO:LiTaO3 crystal as a gain medium for 1083 nm lasers

    NASA Astrophysics Data System (ADS)

    Zhang, P. X.; Gong, J.; Hang, Y.; Li, Hongqiang; Zhang, Rui; Xu, Jianqiu

    2013-04-01

    The growth, spectroscopic properties, laser parameters, and laser performance of a Nd3+/Mg2+ co-doped congruent LiTaO3 crystal were investigated. Continuous-wave (cw) laser operation at a wavelength of about 1083 nm with a slope efficiency of nearly 12% was achieved. The maximum cw output power obtained was 615 mW, which, to the best of our knowledge, is the highest output power obtained for this crystal thus far. We propose that Nd:MgO:LiTaO3 lasers could be an excellent source for the optical pumping of helium, and may achieve second harmonic generation and optical parametric oscillation in the same crystal.

  7. Photonic-crystal lasers on silicon for chip-scale optical interconnects

    NASA Astrophysics Data System (ADS)

    Takeda, Koji; Fujii, Takuro; Shinya, Akihiko; Kuramochi, Eiichi; Notomi, Masaya; Hasebe, Koichi; Kakitsuka, Takaaki; Matsuo, Shinji

    2016-03-01

    Optical interconnects are expected to reduce the power consumption of ICT instruments. To realize chip-to-chip or chip-scale optical interconnects, it is essential to fabricate semiconductor lasers with a smaller energy cost. In this context, we are developing lambda-scale embedded active-region photonic-crystal (LEAP) lasers as light sources for chip-scale optical interconnects. We demonstrated the first continuous-wave (CW) operation of LEAP lasers in 2012 and reported a record low threshold current and energy cost of 4.8 μA and 4.4 fJ/bit at 10 Gbit/s in 2013. We have also integrated photonic crystal photodetectors on the same InP chip and demonstrated waveform transfer along 500-μm-long waveguides. Although LEAP lasers exhibit excellent performance, they have to be integrated on Si wafers for use as light sources for chip-scale optical interconnects. In this paper, we give a brief overview of our LEAP lasers on InP and report our recent progress in fabricating them on Si. We bonded the InP wafers with quantum-well gain layers directly on thermally oxidized Si wafers and performed all process steps on the Si wafer, including high-temperature regrowth. After this process modification, we again achieved CW operation and obtained a threshold current of 57 μA with a maximum output power of more than 3.5 μW at the output waveguides. An output light was successfully guided through 500 × 250-nm InP waveguides.

  8. Direct Phasing of Finite Crystals Illuminated with a Free-Electron Laser

    NASA Astrophysics Data System (ADS)

    Kirian, Richard A.; Bean, Richard J.; Beyerlein, Kenneth R.; Barthelmess, Miriam; Yoon, Chun Hong; Wang, Fenglin; Capotondi, Flavio; Pedersoli, Emanuele; Barty, Anton; Chapman, Henry N.

    2015-01-01

    It has been suggested that the extended intensity profiles surrounding Bragg reflections that arise when a series of finite crystals of varying size and shape are illuminated by the intense, coherent illumination of an x-ray free-electron laser may enable the crystal's unit-cell electron density to be obtained ab initio via well-established iterative phasing algorithms. Such a technique could have a significant impact on the field of biological structure determination since it avoids the need for a priori information from similar known structures, multiple measurements near resonant atomic absorption energies, isomorphic derivative crystals, or atomic-resolution data. Here, we demonstrate this phasing technique on diffraction patterns recorded from artificial two-dimensional microcrystals using the seeded soft x-ray free-electron laser FERMI. We show that the technique is effective when the illuminating wavefront has nonuniform phase and amplitude, and when the diffraction intensities cannot be measured uniformly throughout reciprocal space because of a limited signal-to-noise ratio.

  9. Tunable multi-wavelength polymer laser based on a triangular-lattice photonic crystal structure

    NASA Astrophysics Data System (ADS)

    Huang, Wenbin; Pu, Donglin; Qiao, Wen; Wan, Wenqiang; Liu, Yanhua; Ye, Yan; Wu, Shaolong; Chen, Linsen

    2016-08-01

    A continuously tunable multi-wavelength polymer laser based on a triangular-lattice photonic crystal cavity is demonstrated. The triangular-lattice resonator was initially fabricated through multiple interference exposure and was then replicated into a low refractive index polymer via UV-nanoimprinting. The blend of a blue-emitting conjugated polymer and a red-emitting one was used as the gain medium. Three periods in the scalene triangular-lattice structure yield stable tri-wavelength laser emission (625.5 nm, 617.4 nm and 614.3 nm) in six different directions. A uniformly aligned liquid crystal (LC) layer was incorporated into the cavity as the top cladding layer. Upon heating, the orientation of LC molecules and thus the effective refractive index of the lasing mode changes which continuously shifts the lasing wavelength. A maximum tuning range of 12.2 nm was observed for the lasing mode at 625.5 nm. This tunable tri-wavelength polymer laser is simple constructed and cost-effective. It may find application in the fields of biosensors and photonic integrated circuits.

  10. Microchip laser operation of Tm,Ho:KLu(WO₄)₂ crystal.

    PubMed

    Loiko, Pavel; Serres, Josep Maria; Mateos, Xavier; Yumashev, Konstantin; Kuleshov, Nikolai; Petrov, Valentin; Griebner, Uwe; Aguiló, Magdalena; Díaz, Francesc

    2014-11-17

    A microchip laser is realized on the basis of a monoclinic Tm,Ho-codoped KLu(WO₄)₂crystal cut for light propagation along the Ng optical indicatrix axis. This crystal cut provides positive thermal lens with extremely weak astigmatism, S/M = 4%. High sensitivity factors, M = dD/dP(abs), of 24.9 and 24.1 m(-1)/W for the mg- and pg- tangential planes are calculated with respect to the absorbed pump power. Such thermo-optic behavior is responsible for mode stabilization in the plano-plano microchip laser cavity, as well as the demonstrated perfect circular beam profile (M(2) < 1.1). Maximum continuous-wave output power of 450 mW is obtained with a slope efficiency of 31%. A set of output couplers is employed to achieve lasing in the spectral range of 2060-2096 nm. The increase of output coupler transmission results in deterioration of the laser performance attributed to the increased up-conversion losses.

  11. Microchip laser operation of Tm,Ho:KLu(WO₄)₂ crystal.

    PubMed

    Loiko, Pavel; Serres, Josep Maria; Mateos, Xavier; Yumashev, Konstantin; Kuleshov, Nikolai; Petrov, Valentin; Griebner, Uwe; Aguiló, Magdalena; Díaz, Francesc

    2014-11-17

    A microchip laser is realized on the basis of a monoclinic Tm,Ho-codoped KLu(WO₄)₂crystal cut for light propagation along the Ng optical indicatrix axis. This crystal cut provides positive thermal lens with extremely weak astigmatism, S/M = 4%. High sensitivity factors, M = dD/dP(abs), of 24.9 and 24.1 m(-1)/W for the mg- and pg- tangential planes are calculated with respect to the absorbed pump power. Such thermo-optic behavior is responsible for mode stabilization in the plano-plano microchip laser cavity, as well as the demonstrated perfect circular beam profile (M(2) < 1.1). Maximum continuous-wave output power of 450 mW is obtained with a slope efficiency of 31%. A set of output couplers is employed to achieve lasing in the spectral range of 2060-2096 nm. The increase of output coupler transmission results in deterioration of the laser performance attributed to the increased up-conversion losses. PMID:25402038

  12. Crystal growth, perfection, linear and nonlinear optical, photoconductivity, dielectric, thermal and laser damage threshold properties of 4-methylimidazolium picrate: an interesting organic crystal for photonic and optoelectronic devices

    NASA Astrophysics Data System (ADS)

    Rajesh, K.; Arun, A.; Mani, A.; Praveen Kumar, P.

    2016-10-01

    The 4-methylimidazolium picrate has been synthesized and characterized successfully. Single and powder x-ray diffraction studies were conducted which confirmed the crystal structure, and the value of the strain was calculated. The crystal perfection was determined by a HRXR diffractometer. The transmission spectrum exhibited a better transmittance of the crystal in the entire visible region with a lower cut-off wavelength of 209 nm. The linear absorption value was calculated by the optical limiting method. A birefringence study was also carried out. Second and third order nonlinear optical properties of the crystal were found by second harmonic generation and the z-scan technique. The crystals were also characterized by dielectric measurement and a photoconductivity analyzer to determine the dielectric property and the optical conductivity of the crystal. The laser damage threshold activity of the grown crystal was studied by a Q-switched Nd:YAG laser beam. Thermal studies established that the compound did not undergo a phase transition and was stable up to 240 °C.

  13. Nanostructured lead sulfide: synthesis, structure and properties

    NASA Astrophysics Data System (ADS)

    Sadovnikov, S. I.; Gusev, A. I.; Rempel, A. A.

    2016-07-01

    The theoretical and experimental results of recent studies dealing with nanostructured lead sulfide are summarized and analyzed. The key methods for the synthesis of nanostructured lead sulfide are described. The crystal structure of PbS in nanopowders and nanofilms is discussed. The influence of the size of nanostructure elements on the optical and thermal properties of lead sulfide is considered. The dependence of the band gap of PbS on the nanoparticle (crystallite) size for powders and films is illustrated. The bibliography includes 222 references.

  14. A chromogenic limulus test for detection of microbes that decreases the laser damage threshold of potassium dihydrogen phosphate crystals

    NASA Astrophysics Data System (ADS)

    Yokotani, A.; Nishida, Y.; Fujioka, K.; Sasaki, T.; Yamanaka, T.; Yamanaka, C.

    1987-05-01

    The chromogenic limulus test has been applied for the first time to detect an organic impurity contained in potassium dihydrogen phosphate (KDP) crystals. Impurities arise from microbes present during crystal growth, and are responsible for a reduced laser damage threshold. A sensitivity of 10 pg/g KDP (10-5 ppm) was achieved, provided that the KDP solution was neutralized to ˜pH 7. Endotoxin content in the prismatic region of KDP crystals grown in a microbe-rich solution was approximately 100 pg/g KDP. The presence of an organic material in seemingly perfect KDP crystals could be experimentally confirmed.

  15. The interaction of 193-nm excimer laser irradiation with single-crystal zinc oxide: Neutral atomic zinc and oxygen emission

    SciTech Connect

    Kahn, E. H.; Langford, S. C.; Dickinson, J. T.; Boatner, Lynn A

    2013-01-01

    We report mass-resolved time-of-flight measurements of neutral particles from the surface of single-crystal ZnO during pulsed 193-nm irradiation at laser fluences below the threshold for avalanche breakdown. The major species emitted are atomic Zn and O. We examine the emissions of atomic Zn as a function of laser fluence and laser exposure. Defects at the ZnO surface appear necessary for the detection of these emissions. Our results suggest that the production of defects is necessary to explain intense sustained emissions at higher fluence. Rapid, clean surface etching and high atomic zinc kinetic energies seen at higher laser fluences are also discussed.

  16. Simulation of birefringence effects on the dominant transversal laser resonator mode caused by anisotropic crystals.

    PubMed

    Asoubar, Daniel; Zhang, Site; Wyrowski, Frank

    2015-06-01

    Birefringence effects can have a significant influence on the polarization state as well as on the transversal mode structure of laser resonators. This work introduces a flexible, fast and fully vectorial algorithm for the analysis of resonators containing homogeneous, anisotropic optical components. It is based on a generalization of the Fox and Li algorithm by field tracing, enabling the calculation of the dominant transversal resonator eigenmode. For the simulation of light propagation through the anisotropic media, a fast Fourier Transformation (FFT) based angular spectrum of plane waves approach is introduced. Besides birefringence effects, this technique includes intra-crystal diffraction and interface refraction at crystal surfaces. The combination with numerically efficient eigenvalue solvers, namely vector extrapolation methods, ensures the fast convergence of the method. Furthermore a numerical example is presented which is in good agreement to experimental measurements. PMID:26072756

  17. Amplitude autocorrelation of femtosecond laser pulses using linear photogalvanic effect in sillenite crystals

    NASA Astrophysics Data System (ADS)

    Grachev, A. I.; Romashko, R. V.; Kulchin, Yu. N.; Golik, S. S.; Nippolainen, E.; Kamshilin, A. A.

    2012-06-01

    We demonstrate excitation of the linear photogalvanic current in a Bi12TiO20 crystal by two orthogonally polarized femtosecond laser pulses with detecting the electrical current via charge accumulation on the sample electrodes. Such a setup was used to implement an interferometric autocorrelation technique for characterization of ultrashort light pulses. Integration of the detected current in femtosecond time domain leads to vanishing of a bipolar component of the photogalvanic current which arises due to a pulse chirping. The advantage of the proposed technique is that it produces the electric field correlation function directly without the need for data processing using a compact, robust, and non-expensive detector in the form of a photoconductive cell of a non-centrosymmetric crystal.

  18. Laser-written photonic crystal optofluidics for electrochromatography and spectroscopy on a chip

    PubMed Central

    Haque, Moez; Zacharia, Nicole S.; Ho, Stephen; Herman, Peter R.

    2013-01-01

    Femtosecond laser processes were optimized for nonlinear interactions with various optical materials to develop a novel biophotonic lab-on-a-chip device that integrates laser-formed waveguides (WGs), microfluidic channels and photonic crystals (PCs). Such integration seeks the unique demonstration of dual PC functionalities: (1) efficient chromatographic separation and filtration of analytes through a porous PC embedded inside a microfluidic channel and (2) optofluidic spectroscopy through embedded WGs that probe PC stopband shifts as varying analyte concentrations flow and separate. The building blocks together with their integration were demonstrated, providing embedded porous PCs through which electrochromatography drove an accelerated mobile phase of analyte and an optical stopband was probed via integrated buried WGs. Together, these laboratory results underpin the promise of simultaneous chromatographic and spectroscopic capabilities in a single PC optofluidic device. PMID:24010009

  19. 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.

  20. Cholesteric liquid crystal laser in a dielectric mirror cavity upon band-edge excitation

    NASA Astrophysics Data System (ADS)

    Matsuhisa, Yuko; Huang, Yuhua; Zhou, Ying; Wu, Shin-Tson; Takao, Yuuki; Fujii, Akihiko; Ozaki, Masanori

    2007-01-01

    Low threshold laser action of dye-doped cholesteric liquid crystals (CLCs) is demonstrated using an input circularly polarized light whose handedness is the same as the cholesteric helix of the sample at the high-energy band edge of the reflection band. The mechanism originates from the dramatic increase of the photon density of state at the band edges. We also demonstrate an enhanced laser action of a CLC in a dielectric multilayer cavity. In such a device configuration, the band-edge excitation at high-energy band edge improves the lasing performance not only for the same handedness circularly polarized pump beam as the cholesteric helix but also for the opposite one. It stems from the polarization independence of the dielectric multilayers.

  1. Laser-Directed Hierarchical Assembly of Liquid Crystal Defects and Control of Optical Phase Singularities

    SciTech Connect

    Ackerman, P. J.; Qi, Z. Y.; Lin, Y. H.; Twombly, C. W.; Laviada, M. J.; Lansac, Y.; Smalyukh, I. I.

    2012-06-07

    Topological defect lines are ubiquitous and important in a wide variety of fascinating phenomena and theories in many fields ranging from materials science to early-universe cosmology, and to engineering of laser beams. However, they are typically hard to control in a reliable manner. Here we describe facile erasable 'optical drawing' of self-assembled defect clusters in liquid crystals. These quadrupolar defect clusters, stabilized by the medium's chirality and the tendency to form twisted configurations, are shaped into arbitrary two-dimensional patterns, including reconfigurable phase gratings capable of generating and controlling optical phase singularities in laser beams. Our findings bridge the studies of defects in condensed matter physics and optics and may enable applications in data storage, singular optics, displays, electro-optic devices, diffraction gratings, as well as in both optically- and electrically-addressed pixel-free spatial light modulators.

  2. Laser-directed hierarchical assembly of liquid crystal defects and control of optical phase singularities

    PubMed Central

    Ackerman, Paul J.; Qi, Zhiyuan; Lin, Yiheng; Twombly, Christopher W.; Laviada, Mauricio J.; Lansac, Yves; Smalyukh, Ivan I.

    2012-01-01

    Topological defect lines are ubiquitous and important in a wide variety of fascinating phenomena and theories in many fields ranging from materials science to early-universe cosmology, and to engineering of laser beams. However, they are typically hard to control in a reliable manner. Here we describe facile erasable “optical drawing” of self-assembled defect clusters in liquid crystals. These quadrupolar defect clusters, stabilized by the medium's chirality and the tendency to form twisted configurations, are shaped into arbitrary two-dimensional patterns, including reconfigurable phase gratings capable of generating and controlling optical phase singularities in laser beams. Our findings bridge the studies of defects in condensed matter physics and optics and may enable applications in data storage, singular optics, displays, electro-optic devices, diffraction gratings, as well as in both optically- and electrically-addressed pixel-free spatial light modulators. PMID:22679553

  3. Optical characterization of femtosecond laser induced active channel waveguides in lithium fluoride crystals

    SciTech Connect

    Chiamenti, I.; Kalinowski, H. J.; Bonfigli, F.; Montereali, R. M.; Gomes, A. S. L.; Michelotti, F.

    2014-01-14

    We successfully realized broad-band light-emitting color center waveguides buried in LiF crystals by using femtosecond laser pulses. The characterization of the waveguides was performed by optical microscopy, photoluminescence spectra, loss measurements and near-field profiling. The experimental results show that the direct-writing fabrication process induces low-index contrast active channel waveguides: their wavelength-dependent refractive index changes, estimated from 10{sup −3} to 10{sup −4} depending on the writing conditions, allow supporting few modes at visible and near-infrared wavelengths.

  4. Amplification of cylindrically polarized laser beams in single crystal fiber amplifiers.

    PubMed

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

    2013-05-01

    Yb:YAG single crystal fiber (SCF) amplifiers have recently drawn much attention in the field of amplification of ultra-short pulses. In this paper, we report on the use of SCF amplifiers for the amplification of cylindrically polarized laser beams, as such beams offer promising properties for numerous applications. While the amplification of cylindrically polarized beams is challenging with other amplifier designs due to thermally induced depolarization, we demonstrate the amplification of 32 W cylindrically polarized beams to an output power of 100 W. A measured degree of radial polarization after the SCF of about 95% indicates an excellent conservation of polarization.

  5. Direct writing of ferroelectric domains on strontium barium niobate crystals using focused ultraviolet laser light

    SciTech Connect

    Boes, Andreas; Crasto, Tristan; Steigerwald, Hendrik; Mitchell, Arnan; Wade, Scott; Frohnhaus, Jakob; Soergel, Elisabeth

    2013-09-30

    We report ferroelectric domain inversion in strontium barium niobate (SBN) single crystals by irradiating the surface locally with a strongly focused ultraviolet (UV) laser beam. The generated domains are investigated using piezoresponse force microscopy. We propose a simple model that allows predicting the domain width as a function of the irradiation intensity, which indeed applies for both SBN and LiNbO{sub 3}. Evidently, though fundamentally different, the domain structure of both SBN and LiNbO{sub 3} can be engineered through similar UV irradiation.

  6. Three-dimensional Dielectric Photonic Crystal Structures for Laser-driven Acceleration

    SciTech Connect

    Cowan, Benjamin M.; /Tech-X, Boulder /SLAC

    2007-12-14

    We present the design and simulation of a three-dimensional photonic crystal waveguide for linear laser-driven acceleration in vacuum. The structure confines a synchronous speed-of-light accelerating mode in both transverse dimensions. We report the properties of this mode, including sustainable gradient and optical-to-beam efficiency. We present a novel method for confining a particle beam using optical fields as focusing elements. This technique, combined with careful structure design, is shown to have a large dynamic aperture and minimal emittance growth, even over millions of optical wavelengths.

  7. Laser-cooled atoms inside a hollow-core photonic-crystal fiber

    SciTech Connect

    Bajcsy, M.; Hofferberth, S.; Balic, V.; Zibrov, A. S.; Lukin, M. D.; Peyronel, T.; Liang, Q.; Vuletic, V.

    2011-06-15

    We describe the loading of laser-cooled rubidium atoms into a single-mode hollow-core photonic-crystal fiber. Inside the fiber, the atoms are confined by a far-detuned optical trap and probed by a weak resonant beam. We describe different loading methods and compare their trade-offs in terms of implementation complexity and atom-loading efficiency. The most efficient procedure results in loading of {approx}30,000 rubidium atoms, which creates a medium with an optical depth of {approx}180 inside the fiber. Compared to our earlier study this represents a sixfold increase in the maximum achieved optical depth in this system.

  8. Fabrication of two-dimensional metallic photonic crystals using laser interference ablation

    NASA Astrophysics Data System (ADS)

    Pang, Zhaoguang; Zhang, Xinping; Liu, Hongmei; Zhai, Tianrui

    2012-11-01

    We demonstrate the fabrication of two-dimensional (2D) metallic photonic crystals (MPCs) based on colloidal gold nanoparticles, where laser interference ablation combining subsequent high temperature annealing is employed for the construction of 2D gold nano-dot arrays in square lattices. The microscopic and spectroscopic properties of the 2-D MPCs are systematically characterized by the scanning electron microscope and the angle-resolved optical extinction spectroscopic measurements, the strong coupling between the waveguide resonance mode and the particle plasmon resonance of the MPCs imply the success of the fabrication method, which show potential applications in optoelectronic devices and sensors.

  9. Terahertz quantum cascade lasers based on two-dimensional photonic crystal resonators.

    PubMed

    Sirigu, Lorenzo; Terazzi, Romain; Amanti, Maria I; Giovannini, Marcella; Faist, Jèrome; Dunbar, L Andrea; Houdré, Romuald

    2008-04-14

    We demonstrate high spectral control from surface emitting THz Quantum Cascade Lasers based on a two-dimensional photonic crystal cavity. The perforated top metallic contact acts as an in plane resonator in a tight double-metal plasmonic waveguide providing a strong optical feedback without needing three-dimensional cavity features. The optical far-field patterns do not exhibit the expected symmetry and the shape of the cavity mode. The difference is attributed to a metal surface plasmon mediated light outcoupling mechanism also responsible for the relatively low extraction efficiency. PMID:18542623

  10. Luminescence of crystals under the action of subnanosecond electron beam and laser radiation

    NASA Astrophysics Data System (ADS)

    Lipatov, E. I.; Tarasenko, V. F.; Orlovskii, V. M.; Alekseev, S. B.

    2006-02-01

    The studies of luminescence of synthetic ruby, natural spodumene and natural IIa type diamond under the action of laser radiation at 222 nm and subnanosecond avalanche electron beam (SAEB) were carried out. It was demonstrated that SAEB parameters allow obtaining high-intensity luminescence of various crystals in the normal conditions without any vacuum equipment used. At the both types of excitation, ruby emission spectra were similar demonstrating luminescence of chrome only. It was shown that photoluminescence spectra of the spodumene and diamond samples contained some bands being absent in SAEB-initiated cathodoluminescence spectra.

  11. Sulfide chemiluminescence detection

    DOEpatents

    Spurlin, Stanford R.; Yeung, Edward S.

    1985-01-01

    A method of chemiluminescently determining a sulfide which is either hydrogen sulfide or methyl mercaptan by reacting the sulfide with chlorine dioxide at low pressure and under conditions which allow a longer reaction time in emission of a single photon for every two sulfide containing species, and thereafter, chemiluminescently detecting and determining the sulfide. The invention also relates not only to the detection method, but the novel chemical reaction and a specifically designed chemiluminescence detection cell for the reaction.

  12. Sulfide chemiluminescence detection

    DOEpatents

    Spurlin, S.R.; Yeung, E.S.

    1985-11-26

    A method is described for chemiluminescently determining a sulfide which is either hydrogen sulfide or methyl mercaptan by reacting the sulfide with chlorine dioxide at low pressure and under conditions which allow a longer reaction time in emission of a single photon for every two sulfide containing species, and thereafter, chemiluminescently detecting and determining the sulfide. The invention also relates not only to the detection method, but the novel chemical reaction and a specifically designed chemiluminescence detection cell for the reaction. 4 figs.

  13. Nickel-affected silicon crystallization and silicidation on polyimide by multipulse excimer laser annealing

    SciTech Connect

    Alberti, A.; La Magna, A.; Spinella, C.; Privitera, V.; Cuscuna, M.; Fortunato, G.

    2010-12-15

    Nickel enhanced amorphous Si crystallization and silicidation on polyimide were studied during multipulse excimer laser annealing (ELA) from submelting to melting conditions. A {approx}8 nm thick Ni film was deposited on a 100 nm thick {alpha}-Si layer at {approx}70 deg. C in order to promote partial nickel diffusion into silicon. In the submelting regime, Ni atoms distributed during deposition in {alpha}-Si and the thermal gradient due to the presence of the plastic substrate were crucial to induce low fluence ({>=}0.08 J/cm{sup 2}) Si crystallization to a depth which is strictly related to the starting Ni profile. {Alpha}morphous-Si crystallization is not expected on pure Si at those low fluences. Additional pulses at higher fluences do not modify the double poly-Si/{alpha}-Si structure until melting conditions are reached. At a threshold of {approx}0.2 J/cm{sup 2}, melting was induced simultaneously in the polycrystalline layer as well as in the residual {alpha}-Si due to a thermal gradient of {approx}200 deg. C. Further increasing the laser fluence causes the poly-Si layer to be progressively melted to a depth which is proportional to the energy density used. As a consequence of the complete Si melting, columnar poly-Si grains are formed above 0.3 J/cm{sup 2}. For all fluences, a continuous NiSi{sub 2} layer is formed at the surface which fills the large Si grain boundaries, with the beneficial effect of flattening the poly-Si surface. The results would open the perspective of integrating Ni-silicide layers as metallic contacts on Si during {alpha}-Si-crystallization by ELA on plastic substrate.

  14. INTERACTION OF LASER RADIATION WITH MATTER: Luminescence of crystals excited by a KrCl laser and a subnanosecond electron beam

    NASA Astrophysics Data System (ADS)

    Lipatov, E. I.; Tarasenko, Viktor F.; Orlovskii, Viktor M.; Alekseev, S. B.

    2005-08-01

    Luminescence of crystals of natural spodumene and natural diamond of the type IIa is studied upon excitation by a laser at a wavelength of 222 nm and by a subnanosecond avalanche electron beam (SAEB) formed in air at the atmospheric pressure. The photoluminescence spectra of spodumene and diamond are shown to exhibit additional bands, which are absent upon SAEB excitation. It is demonstrated that SAEB excitation allows one to analyse various crystals under normal conditions without using any vacuum equipment.

  15. Broadband coherent light generation in Raman-active crystals driven by femtosecond laser fields

    NASA Astrophysics Data System (ADS)

    Zhi, Miaochan

    I studied a family of closely connected topics related to the production and application of ultrashort laser pulses. I achieved broadband cascade Raman generation in crystals, producing mutually coherent frequency sidebands which can possibly be used to synthesize optical pulses as short as a fraction of a femtosecond (fs). Unlike generation using gases, there is no need for a cumbersome vacuum system when working with room temperature crystals. Our method, therefore, shows promise for a compact system. One problem for sideband generation in solids is phase matching, because the dispersion is significant. I solved this problem by using non-collinear geometry. I observed what to our knowledge is a record-large number of spectral sidebands generated in a popular Raman crystal PbWO4 covering infrared, visible, and ultraviolet spectral regions, when I applied two 50 fs laser pulses tuned close to the Raman resonance. Similar generation in diamond was also observed, which shows that the method is universal. When a third probe pulse is applied, a very interesting 2-D color array is generated in both crystals. As many as 40 anti-Stokes and 5 Stokes sidebands are generated when a pair of time-delayed linear chirped pulses are applied to the PbWO4 crystal. This shows that pulses with picosecond duration, which is on the order of the coherence decay time, is more effective for sidebands generation than Fourier transform limited fs pulses. I also studied the technique of fs coherent Raman anti-Stokes scattering (CARS) which is used as a tool for detecting dipicolinic acid, the marker molecule for bacterial spores. I observed that there is a maximum when the concentration dependence of the near-resonant CARS signal is measured. I presented a model to describe this behavior, and found an analytical solution that agrees with our experimental data. Theoretically, I explored a possible application for single-cycle pulses: laser induced nuclear fusion. I performed both classical

  16. Laser patterning and preferential orientation of two-dimensional planar {beta}-BaB{sub 2}O{sub 4} crystals on the glass surface

    SciTech Connect

    Suzuki, F.; Ogawa, K.; Honma, T.; Komatsu, T.

    2012-01-15

    The laser-induced crystallization method is applied to pattern two-dimensional planar {beta}-BaB{sub 2}O{sub 4} crystals on the surface of Sm{sub 2}O{sub 3}-BaO-B{sub 2}O{sub 3} glass. By scanning Yb:YVO{sub 4} fiber lasers (wavelength: 1080 nm) continuously with a small step (0.5 {mu}m) between laser irradiated areas, homogeneous planar {beta}-BaB{sub 2}O{sub 4} crystals are patterned successfully, and a preferential growth orientation of {beta}-BaB{sub 2}O{sub 4} crystals is confirmed from linearly polarized micro-Raman scattering spectrum and second harmonic intensity measurements. It is found that the crystal growth direction is perpendicular to the laser scanning direction. This relation, i.e., the perpendicular relation, is different from the behavior in discrete crystal line patterning, where the crystal growth direction is consistent with the laser scanning direction. The present study proposes the possibility of the control of crystal growth direction in laser-induced crystallization in glasses. - Graphical abstract: This figure shows confocal scanning laser microscope and polarized optical microscope photographs for {beta}-BaB{sub 2}O{sub 4} crystals obtained by laser irradiations. The laser scanning was repeated with a step of 0.5 {mu}m between the lines using the condition of the power of P=0.8 W and a laser scanning speed of S=8 {mu}m/s. It is suggested that {beta}-BaB{sub 2}O{sub 4} crystals in the overlapped laser-irradiated region are highly oriented and the c-axis direction of {beta}-BaB{sub 2}O{sub 4} crystals is perpendicular to the laser scanning direction. Highlights: Black-Right-Pointing-Pointer Laser-induced crystallization method is applied to pattern {beta}-BaB{sub 2}O{sub 4} crystals. Black-Right-Pointing-Pointer Two-dimensional planar crystals are patterned on the glass surface. Black-Right-Pointing-Pointer Preferential growth orientation of {beta}-BaB{sub 2}O{sub 4} crystals is confirmed. Black-Right-Pointing-Pointer Crystal growth

  17. Sulfidation of iron at high temperatures and diffusion kinetics in ferrous sulfide

    SciTech Connect

    Danielewski, M.; Mrowec, S.; Stoklosa, A.

    1982-02-01

    The kinetics and mechanism of iron sulfidation have been studied as a function of temperature (950-1200 K) and sulfur pressure (10/sup -3/ 0.065 atm). It has been stated that a compact Fe/sub 1-y/ S scale on iron grows according to the parabolic rate law as a result of outward lattice diffusion of metal ions through cation vacancies. The activation energy of sulfidation increases with sulfur pressure and the 1/n exponent increases with temperature. This nontypical dependence of iron sulfidation kinetics on temperature and pressure results from the analogous effect of both these parameters on defect concentration in ferrous sulfide. The chemical diffusion coefficients, D/sub FeS/ , and diffusion coefficients of defects, D/sub d/ , in ferrous sulfide have been calculated on the basis of parabolic rate contacts of iron sulfidation and deviations from stoichiometry in ferrous sulfide. It has been shown that D/sub FeS/ is practically independent of cation vacancy concentration whereas the diffusion coefficient of defects depends strongly on that parameter. A comparison of self-diffusion coefficients of iron in Fe/sub 1-y/ S calculated from the kinetics of iron sulfidation to those obtained from radioisotopic studies indicates that within the range studied of temperatures and sulfur vapor pressures the outward diffusion of iron across the scale occurs preferentially along the c axis of columnar ferrous sulfide crystals.

  18. Laser induced surface damage, thermal transport and microhardness studies on certain organic and semiorganic nonlinear optical crystals

    NASA Astrophysics Data System (ADS)

    Manivannan, S.; Dhanuskodi, S.; Tiwari, S. K.; Philip, J.

    2008-03-01

    N-alkyl-2,6-dimethyl-4(1H)-pyridinones, salts of 4-dimethylaminopyridine and 2-amino-5-nitropyridine are considered to be potential candidates for nonlinear optical (NLO) applications, in particular for the generation of blue-green laser radiation. Single crystals were grown following the slow evaporation technique at constant temperature. Single-shot laser-induced surface damage thresholds in the range 3-10 GW/cm2 were measured using a 18 ns Q-switched Nd:YAG laser. The surface morphologies of the damaged crystals were examined under an optical microscope and the nature of damage identified. The Vicker’s microhardness was determined at a load of 98.07 mN. The thermal transport properties, thermal diffusivity (α), thermal effusivity (e), thermal conductivity (K) and heat capacity (Cp), of the grown crystals were measured by an improved photopyroelectric technique at room temperature. All the results are presented and discussed.

  19. Reactivity of Sulfide Mineral Surfaces

    SciTech Connect

    Rosso, Kevin M.; Vaughan, David J.

    2006-08-01

    In the preceding chapter, the fundamental nature of sulfide mineral surfaces has been discussed, and the understanding we have of the ways in which the surface differs from a simple truncation of the bulk crystal structure reviewed. This naturally leads on to considering our understanding of sulfide surface chemistry, in the sense of how sulfide surfaces interact and react, particularly with gases and liquids. As noted elsewhere in this volume, research on sulfide mineral surfaces and surface reactivity is a relatively recent concern of mineralogists and geochemists, partly prompted by the availability of new imaging and spectroscopic methods, powerful computers and new computer algorithms. There has been a significantly longer history of sulfide mineral surface research associated with technologists working with, or within, the mining industry. Here, electrochemical methods, sometimes combined with analytical and spectroscopic techniques, have been used to probe surface chemistry. The motivation for this work has been to gain a better understanding of the controls of leaching reactions used to dissolve out metals from ores, or to understand the chemistry of the froth flotation systems used in concentrating the valuable (usually sulfide) minerals prior to metal extraction. The need for improved metal extraction technologies is still a major motivation for research on sulfide surfaces, but in the last couple of decades, new concerns have become important drivers for such work. In particular, much greater awareness of the negative environmental impact of acid and toxic metal-bearing waters derived from breakdown of sulfide minerals at former mining operations has prompted research on oxidation reactions, and on sorption of metals at sulfide surfaces. At the interface between fundamental geochemistry and industrial chemistry, the role of sulfide substrates in catalysis, and in the self-assembly and functionalization of organic molecules, has become an area of

  20. Colloidal quantum dot lasers built on a passive two-dimensional photonic crystal backbone

    NASA Astrophysics Data System (ADS)

    Chang, Hojun; Min, Kyungtaek; Lee, Myungjae; Kang, Minsu; Park, Yeonsang; Cho, Kyung-Sang; Roh, Young-Geun; Woo Hwang, Sung; Jeon, Heonsu

    2016-03-01

    We report the room-temperature lasing action from two-dimensional photonic crystal (PC) structures composed of a passive Si3N4 backbone with an over-coat of CdSe/CdS/ZnS colloidal quantum dots (CQDs) for optical gain. When optically excited, devices lased in dual PC band-edge modes, with the modal dominance governed by the thickness of the CQD over-layer. The demonstrated laser platform should have an impact on future photonic integrated circuits as the on-chip coupling between active and passive components is readily achievable.We report the room-temperature lasing action from two-dimensional photonic crystal (PC) structures composed of a passive Si3N4 backbone with an over-coat of CdSe/CdS/ZnS colloidal quantum dots (CQDs) for optical gain. When optically excited, devices lased in dual PC band-edge modes, with the modal dominance governed by the thickness of the CQD over-layer. The demonstrated laser platform should have an impact on future photonic integrated circuits as the on-chip coupling between active and passive components is readily achievable. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08544f

  1. Increasing the laser-induced damage threshold of single-crystal ZnGeP2

    NASA Astrophysics Data System (ADS)

    Zawilski, Kevin T.; Setzler, Scott D.; Schunemann, Peter G.; Pollak, Thomas M.

    2006-11-01

    The laser-induced damage threshold (LIDT) of single-crystal zinc germanium phosphide (ZGP), ZnGeP2, was increased to 2J/cm2 at 2.05μm and a 10 kHz pulse rate frequency (double the previously measured value of 1 J/cm2). This increased LIDT was achieved by improving the polishing of ZGP optical parametric oscillator crystals. Two different polishing techniques were evaluated. Surfaces were characterized using scanning white-light interferometry to determine rms surface roughness and sample flatness. The photon backscatter technique was used to determine the degree of surface and subsurface damage in the sample induced through the fabrication process. The effect of subsurface damage in the samples was studied by removing different amounts of material during polishing for otherwise identical samples. Statistical LIDT was measured using a high-average-power, repetitively Q-switched Tm,Ho:YLF 2.05μm pump laser. On average, lower surface roughness and photon backscatter measurements were a good indicator of ZGP samples exhibiting higher LIDT. The removal of more material during polishing significantly improved the LIDT of otherwise identical samples, indicating the importance of subsurface damage defects in the LIDT of ZGP.

  2. Laser-induced microexplosion confined in the bulk of a sapphire crystal: evidence of multimegabar pressures.

    PubMed

    Juodkazis, S; Nishimura, K; Tanaka, S; Misawa, H; Gamaly, E G; Luther-Davies, B; Hallo, L; Nicolai, P; Tikhonchuk, V T

    2006-04-28

    Extremely high pressures (approximately 10 TPa) and temperatures (5 x 10(5) K) have been produced using a single laser pulse (100 nJ, 800 nm, 200 fs) focused inside a sapphire crystal. The laser pulse creates an intensity over 10(14) W/cm2 converting material within the absorbing volume of approximately 0.2 microm3 into plasma in a few fs. A pressure of approximately 10 TPa, far exceeding the strength of any material, is created generating strong shock and rarefaction waves. This results in the formation of a nanovoid surrounded by a shell of shock-affected material inside undamaged crystal. Analysis of the size of the void and the shock-affected zone versus the deposited energy shows that the experimental results can be understood on the basis of conservation laws and be modeled by plasma hydrodynamics. Matter subjected to record heating and cooling rates of 10(18) K/s can, thus, be studied in a well-controlled laboratory environment.

  3. Temporal laser pulse shaping for RF photocathode guns : the cheap and easy way using UV birefringent crystals.

    SciTech Connect

    Power, J. G.; Jing, C.; High Energy Physics; Euclid Techlabs, LLC

    2009-01-01

    We report experimental investigations into a new technique for achieving temporal laser pulse shaping for RF photocathode gun applications using inexpensive UV birefringent crystals. Exploiting the group velocity mismatch between the two different polarizations of a birefringent crystal, a stack of UV pulses can be assembled into the desired temporal pulse shape. The scheme is capable of generating a variety of temporal pulse shapes including: (i) flat-top pulses with fast rise-time and variable pulse duration. (ii) microbunch trains, and (iii) ramped pulse generation. We will consider two applications for beam generation at the Argonne Wakefield Accelerator (AWA) including a flat-top laser pulse for low emittance production and matched bunch length for enhanced transformer ratio production. Streak camera measurements of the temporal profiles generated with a 2-crystal set and a 4-crystal set are presented.

  4. Temporal Laser Pulse Shaping for RF Photocathode Guns: The Cheap and Easy way using UV Birefringent Crystals

    SciTech Connect

    Power, John G.; Jing Chunguang

    2009-01-22

    We report experimental investigations into a new technique for achieving temporal laser pulse shaping for RF photocathode gun applications using inexpensive UV birefringent crystals. Exploiting the group velocity mismatch between the two different polarizations of a birefringent crystal, a stack of UV pulses can be assembled into the desired temporal pulse shape. The scheme is capable of generating a variety of temporal pulse shapes including: (i) flat-top pulses with fast rise-time and variable pulse duration. (ii) microbunch trains, and (iii) ramped pulse generation. We will consider two applications for beam generation at the Argonne Wakefield Accelerator (AWA) including a flat-top laser pulse for low emittance production and matched bunch length for enhanced transformer ratio production. Streak camera measurements of the temporal profiles generated with a 2-crystal set and a 4-crystal set are presented.

  5. Properties of reinforced carbon nanotube and laser-crystallized silicon films

    NASA Astrophysics Data System (ADS)

    Semler, Matthew Roy

    Flexible electronics are anticipated to be one of the next technological advancements of electronic devices. The enhanced durability, light-weight nature, and conformity of flexible electronics are desired properties in a variety of fields and are anticipated to reduce production costs. Two promising materials for use in flexible electronics are carbon nanotube (CNT) films and laser-crystallized thin silicon films. CNTs are in their infancy in respect to their presence in electronic devices; however their superb mechanical and electronic properties make them ideal candidates for flexible electronics. Thin silicon films are a natural transition from bulk silicon as bulk silicon has been the preferred material in electronics since the dawn of the transistor. Thin-film silicon retains the well-studied electronic properties of bulk silicon; however, it becomes flexible as it is thinned. Obstacles to the application of both these materials in flexible electronics nonetheless exist. Compressed CNT films undergo strain softening---a mechanism in which the CNT film restructures itself in response to an applied strain, which reduces the Young's modulus and electronic conductivity. In this dissertation, thin CNT films are capped with a thin polymer layer, with the aim to mitigate strain softening through excluded volume interactions in a bilayer format that serves as a paradigm for more sophisticated device relevant settings. More specifically, metallic and semiconducting CNT films of different thicknesses are capped with a polystyrene film of comparable thickness, and the mechanical and electronic strain response of the capped CNT film is examined and discussed. Ultrathin silicon films cannot be grown as monocrystalline silicon, so amorphous silicon films must be deposited and crystallized. Laser crystallization is an alternative to oven annealing and has a faster throughput. In this dissertation, amorphous silicon films of various thicknesses were deposited on several

  6. Optical data recording by laser pulses in liquid-crystal cells with an azo-modified surface

    SciTech Connect

    Serak, S V; Agashkov, A V; Reshetnyak, V Yu

    2001-03-31

    The effect of trans-cis photoisomerisation of azofragments of a polymer film on the molecular reorientation of a liquid crystal is studied. It is shown that, using nanosecond laser pulses, one can perform both the reversible and static data recording in liquid-crystal cells with an azo-modified surface. The rise time of the reorientation is measured by the methods of dynamic holography to be about {approx} 30 {mu}s, and the grating efficiency achieves 15 %. (laser applications and other topics in quantum electronics)

  7. Measurement of reflectivity of spherically bent crystals using Kα signal from hot electrons produced by laser-matter interaction

    SciTech Connect

    Antonelli, L.; Forestier-Colleoni, P.; Folpini, G.; Bouillaud, R.; Fedeli, L.; Fourment, C.; Giuffrida, L.; Hulin, S.; Santos, J. J.; Volpe, L.; Batani, D.; Faenov, A.; Pikuz, S.

    2015-07-15

    In an experiment at the laser facility ECLIPSE of the CELIA laboratory, University of Bordeaux, we measure the reflectivity of spherically bent crystals that are commonly used to investigate the propagation of fast electrons through the Kα radiation they generate in matter. The experimental reflectivity compares well with predictions from a ray-tracing code that takes into account the specific geometry, although the crystals seem to suffer from aging problems.

  8. Z-scan measurements of the nonlinear refractive indices of novel Yb-doped laser crystal hosts

    NASA Astrophysics Data System (ADS)

    Major, A.; Aitchison, J. S.; Smith, P. W. E.; Druon, F.; Georges, P.; Viana, B.; Aka, G. P.

    2005-02-01

    We report on the z-scan characterization of the nonlinear refractive indices of three borate crystals (GdCOB, YCOB, and BOYS), which are new promising Yb-doped laser hosts. The results indicate the possibility of substantial Kerr-lensing and self-phase modulation effects in femtosecond oscillators and amplifiers. High values of the nonlinear refractive indices suggest possible KLM operation of such lasers.

  9. Photonic crystal fibre enables short-wavelength two-photon laser scanning fluorescence microscopy with fura-2

    NASA Astrophysics Data System (ADS)

    McConnell, Gail; Riis, Erling

    2004-10-01

    We report on a novel and compact reliable laser source capable of short-wavelength two-photon laser scanning fluorescence microscopy based on soliton self-frequency shift effects in photonic crystal fibre. We demonstrate the function of the system by performing two-photon microscopy of smooth muscle cells and cardiac myocytes from the rat pulmonary vein and Chinese hamster ovary cells loaded with the fluorescent calcium indicator fura-2/AM.

  10. Live-monitoring of Te inclusions laser-induced thermo-diffusion and annealing in CdZnTe crystals

    SciTech Connect

    Zappettini, A.; Zambelli, N.; Benassi, G.; Calestani, D.; Pavesi, M.

    2014-06-23

    The presence of Te inclusions is one of the main factors limiting performances of CdZnTe crystals as X-ray detectors. We show that by means of infrared laser radiation it is possible to move and anneal tellurium inclusions exploiting a thermo-diffusion mechanism. The process is studied live during irradiation by means of an optical microscope equipment. Experimental conditions, and, in particular, energy laser fluence, for annealing inclusions of different dimensions are determined.

  11. Hard x-ray transmission crystal spectrometer at the OMEGA-EP laser facilitya)

    NASA Astrophysics Data System (ADS)

    Seely, J. F.; Szabo, C. I.; Feldman, U.; Hudson, L. T.; Henins, A.; Audebert, P.; Brambrink, E.

    2010-10-01

    The transmission crystal spectrometer (TCS) is approved for taking data at the OMEGA-EP laser facility since 2009 and will be available for the OMEGA target chamber in 2010. TCS utilizes a Cauchois type cylindrically bent transmission crystal geometry with a source to crystal distance of 600 mm. Spectral images are recorded by image plates in four positions, one IP on the Rowland circle and three others at 200, 400, and 600 mm beyond the Rowland circle. An earlier version of TCS was used at LULI on experiments that determined the x-ray source size from spectral line broadening on one IP positioned behind the Rowland circle. TCS has recorded numerous backlighter spectra at EP for point projection radiography and for source size measurements. Hard x-ray source size can be determined from the source broadening of both K shell emission lines and from K absorption edges in the bremsstrahlung continuum, the latter being a new way to measure the spatial extent of the hard x-ray bremsstrahlung continuum.

  12. Hard x-ray transmission crystal spectrometer at the OMEGA-EP laser facility.

    PubMed

    Seely, J F; Szabo, C I; Feldman, U; Hudson, L T; Henins, A; Audebert, P; Brambrink, E

    2010-10-01

    The transmission crystal spectrometer (TCS) is approved for taking data at the OMEGA-EP laser facility since 2009 and will be available for the OMEGA target chamber in 2010. TCS utilizes a Cauchois type cylindrically bent transmission crystal geometry with a source to crystal distance of 600 mm. Spectral images are recorded by image plates in four positions, one IP on the Rowland circle and three others at 200, 400, and 600 mm beyond the Rowland circle. An earlier version of TCS was used at LULI on experiments that determined the x-ray source size from spectral line broadening on one IP positioned behind the Rowland circle. TCS has recorded numerous backlighter spectra at EP for point projection radiography and for source size measurements. Hard x-ray source size can be determined from the source broadening of both K shell emission lines and from K absorption edges in the bremsstrahlung continuum, the latter being a new way to measure the spatial extent of the hard x-ray bremsstrahlung continuum. PMID:21034000

  13. Laser induced nanoparticle formation in single crystal CaF2

    NASA Astrophysics Data System (ADS)

    Cramer, L.; Langford, S. C.; Dickinson, J. T.

    2004-03-01

    Single crystal calcium fluoride (CaF2) is a material currently being used for vacuum ultra-violet optical components. However, all metal halides have a strong tendency to form point defects under energetic particle and optical irradiation which can degrade performance. Here we examine the consequences of exposing CaF2 to 157 nm excimer laser light. This exposure causes absorption in the visible region due to formations of nanoclusters (colloids) of Ca metal in the bulk. The formation mechanism involves exciton production via two photon absorption. Heating can affect the colloid growth; we have examined the change of transmission at 532 nm vs. temperature during coloring with 157 nm excimer laser light. We find maximum coloration to occur at 50 C. The colloids can also be easily made with exposure to low-energy electrons. The absorption due to colloids can be bleached with subsequent exposure to appropriate laser light. We compare bleaching rates at various wavelengths from 157-1064 nm and find that absorption due to plasmon excitation in the colloids and accompanying heating is the likely bleaching mechanism.

  14. Surface-emitting mid-infrared quantum cascade lasers with high-contrast photonic crystal resonators.

    PubMed

    Xu, Gangyi; Colombelli, Raffaele; Braive, Remy; Beaudoin, Gregoire; Le Gratiet, Luc; Talneau, Anne; Ferlazzo, Laurence; Sagnes, Isabelle

    2010-05-24

    We have developed surface-emitting single-mode quantum cascade lasers which employ high-contrast photonic-crystal resonators. The devices operate on band-edge states of the photonic band-structure. The mode profile and polarization characteristics of the band-edge modes are calculated by three-dimensional finite-difference time-domain simulation. Experimentally, the spectral properties, the far-field patterns, and the polarization characteristics of the lasers are determined and compared with simulations. The good agreement between the simulations and the experiments confirms that the hexapolar mode at the Gamma-point band-edge gives rise to lasing. By using a novel and advanced fabrication method, deep and vertical PhC holes are fabricated with no metal redeposition on the sidewalls, which improves the laser performance with respect to the current status. The angular of the output beam is approximately 15 masculine, and the side mode suppression ratio of the single mode emission is about 25 dB. The threshold current density at 78 K and the maximum operation temperature are 7.6 kA/cm2 and 220 K, respectively. The performance is mainly limited by the loss induced by surface plasmon waveguide, which can be overcome by using an optimized dielectric waveguide structure.

  15. Development of High-Density Plasma Photonic Crystals Using High-Power Lasers

    NASA Astrophysics Data System (ADS)

    Colon Quinones, Roberto; Wang, Benjamin; Lucca Fabris, Andrea; Cappelli, Mark

    2015-09-01

    A plasma photonic crystal (PPC) is an array of plasma structures that interacts with electromagnetic (EM) waves in ways not possible with natural materials. 2D PPCs can be used for generating a band gap, which is a range of wave frequencies in which no waves are transmitted through the structure. Such gap forms when an EM wave travels through a 2D PPC with spacing equal to half the wavelength of the wave and plasma frequency (ωp) on the order of the frequency of the wave. Until recently, research on PPCs has been limited to ωp < 30 GHz, which is equivalent to a plasma density of ne <1013 cm-3 . Over the last year, PPCs of ne >1015 cm-3 have been generated at Stanford through the use of high-power lasers. The PPCs are generated by expanding the laser beam from a Q-switched Nd:YAG laser through a Galilean beam expander and subsequently focusing the beam through an optical micro-lens array. The intense photoionization of air that occurs at the focus of the individual lenses leads to the formation of a 2D array of very dense plasma spots. Photomultiplier measurements show a plasma lifetime of ~150 ns during which the plasma array functions as a PPC, representing a first step towards advancing the field forward into the low THz regime. Sponsored by the AFOSR MURI and DoD NDSEG.

  16. Blue diode-pumped solid-state-laser based on ytterbium doped laser crystals operating on the resonance zero-phonon transition

    DOEpatents

    Krupke, William F.; Payne, Stephen A.; Marshall, Christopher D.

    2001-01-01

    The invention provides an efficient, compact means of generating blue laser light at a wavelength near .about.493+/-3 nm, based on the use of a laser diode-pumped Yb-doped laser crystal emitting on its zero phonon line (ZPL) resonance transition at a wavelength near .about.986+/-6 nm, whose fundamental infrared output radiation is harmonically doubled into the blue spectral region. The invention is applied to the excitation of biofluorescent dyes (in the .about.490-496 nm spectral region) utilized in flow cytometry, immunoassay, DNA sequencing, and other biofluorescence instruments. The preferred host crystals have strong ZPL fluorecence (laser) transitions lying in the spectral range from .about.980 to .about.992 nm (so that when frequency-doubled, they produce output radiation in the spectral range from 490 to 496 nm). Alternate preferred Yb doped tungstate crystals, such as Yb:KY(WO.sub.4).sub.2, may be configured to lase on the resonant ZPL transition near 981 nm (in lieu of the normal 1025 nm transition). The laser light is then doubled in the blue at 490.5 nm.

  17. In situ sulfur isotopes (δ(34)S and δ(33)S) analyses in sulfides and elemental sulfur using high sensitivity cones combined with the addition of nitrogen by laser ablation MC-ICP-MS.

    PubMed

    Fu, Jiali; Hu, Zhaochu; Zhang, Wen; Yang, Lu; Liu, Yongsheng; Li, Ming; Zong, Keqing; Gao, Shan; Hu, Shenghong

    2016-03-10

    The sulfur isotope is an important geochemical tracer in diverse fields of geosciences. In this study, the effects of three different cone combinations with the addition of N2 on the performance of in situ S isotope analyses were investigated in detail. The signal intensities of S isotopes were improved by a factor of 2.3 and 3.6 using the X skimmer cone combined with the standard sample cone or the Jet sample cone, respectively, compared with the standard arrangement (H skimmer cone combined with the standard sample cone). This signal enhancement is important for the improvement of the precision and accuracy of in situ S isotope analysis at high spatial resolution. Different cone combinations have a significant effect on the mass bias and mass bias stability for S isotopes. Poor precisions of S isotope ratios were obtained using the Jet and X cones combination at their corresponding optimum makeup gas flow when using Ar plasma only. The addition of 4-8 ml min(-1) nitrogen to the central gas flow in laser ablation MC-ICP-MS was found to significantly enlarge the mass bias stability zone at their corresponding optimum makeup gas flow in these three different cone combinations. The polyatomic interferences of OO, SH, OOH were also significantly reduced, and the interference free plateaus of sulfur isotopes became broader and flatter in the nitrogen mode (N2 = 4 ml min(-1)). However, the signal intensity of S was not increased by the addition of nitrogen in this study. The laser fluence and ablation mode had significant effects on sulfur isotope fractionation during the analysis of sulfides and elemental sulfur by laser ablation MC-ICP-MS. The matrix effect among different sulfides and elemental sulfur was observed, but could be significantly reduced by line scan ablation in preference to single spot ablation under the optimized fluence. It is recommended that the d90 values of the particles in pressed powder pellets for accurate and precise S isotope analysis

  18. In situ sulfur isotopes (δ(34)S and δ(33)S) analyses in sulfides and elemental sulfur using high sensitivity cones combined with the addition of nitrogen by laser ablation MC-ICP-MS.

    PubMed

    Fu, Jiali; Hu, Zhaochu; Zhang, Wen; Yang, Lu; Liu, Yongsheng; Li, Ming; Zong, Keqing; Gao, Shan; Hu, Shenghong

    2016-03-10

    The sulfur isotope is an important geochemical tracer in diverse fields of geosciences. In this study, the effects of three different cone combinations with the addition of N2 on the performance of in situ S isotope analyses were investigated in detail. The signal intensities of S isotopes were improved by a factor of 2.3 and 3.6 using the X skimmer cone combined with the standard sample cone or the Jet sample cone, respectively, compared with the standard arrangement (H skimmer cone combined with the standard sample cone). This signal enhancement is important for the improvement of the precision and accuracy of in situ S isotope analysis at high spatial resolution. Different cone combinations have a significant effect on the mass bias and mass bias stability for S isotopes. Poor precisions of S isotope ratios were obtained using the Jet and X cones combination at their corresponding optimum makeup gas flow when using Ar plasma only. The addition of 4-8 ml min(-1) nitrogen to the central gas flow in laser ablation MC-ICP-MS was found to significantly enlarge the mass bias stability zone at their corresponding optimum makeup gas flow in these three different cone combinations. The polyatomic interferences of OO, SH, OOH were also significantly reduced, and the interference free plateaus of sulfur isotopes became broader and flatter in the nitrogen mode (N2 = 4 ml min(-1)). However, the signal intensity of S was not increased by the addition of nitrogen in this study. The laser fluence and ablation mode had significant effects on sulfur isotope fractionation during the analysis of sulfides and elemental sulfur by laser ablation MC-ICP-MS. The matrix effect among different sulfides and elemental sulfur was observed, but could be significantly reduced by line scan ablation in preference to single spot ablation under the optimized fluence. It is recommended that the d90 values of the particles in pressed powder pellets for accurate and precise S isotope analysis

  19. Birefringence imaging and orientation of laser patterned β-BaB{sub 2}O{sub 4} crystals with bending and curved shapes in glass

    SciTech Connect

    Ogawa, Kazuki; Honma, Tsuyoshi; Komatsu, Takayuki

    2013-11-15

    Nonlinear optical β-BaB{sub 2}O{sub 4} crystals (β-BBO) with bending and curved shapes were patterned at the surface of 8Sm{sub 2}O{sub 3}–42BaO–50B{sub 2}O{sub 3} glass by laser irradiations (Yb:YVO{sub 4} laser with a wavelength of 1080 nm, power of 0.8 W, and scanning speed of 4 μm/s), and the orientation state of β-BBO crystals was examined from the birefringence imaging obtained by polarization optical microscope (POM) observations. The formation (crystallization) of β-BBO crystals follows along laser scanning direction even if the laser scanning direction changes at a certain point within the bending angle of 60°. The birefringence images indicate that the formation of highly c-axis oriented β-BBO crystals follows along laser scanning direction even if the laser scanning direction changes, and in particular the direction of the c-axis of β-BBO crystals changes gradually at the bending point. The model for the orientation of the c-axis of β-BBO near the bending point is proposed. The present study proposes that the laser-induced crystallization opens a new door for the science and technology in crystal growth engineering. - Graphical abstract: This figure shows the birefringence images obtained by the Abrio IM imaging system (λ=546 nm) for the laser-patterned β-BaB{sub 2}O{sub 4} crystal line with the bending angle of 45° in the glass. The relation between the direction of slow axis and color is also shown. It is demonstrated that the formation (crystallization) of highly c-axis oriented β-BaB{sub 2}O{sub 4} crystals follows along laser scanning direction even if the laser scanning direction changes. Display Omitted - Highlights: • β-BaB{sub 2}O{sub 4} crystals with bending and curved shapes were patterned by laser irradiations. • The orientation was examined from the birefringence imaging. • Highly c-axis oriented crystals follows along laser scanning direction. • The c-axis direction changes gradually at the bending point. • The

  20. Characterization of cobalt doped ZnSe and ZnS crystals as saturable absorbers for alexandrite lasers

    NASA Astrophysics Data System (ADS)

    Sims, Robert A.; Kernal, John; Fedorov, Vladimir V.; Mirov, Sergey B.

    2006-02-01

    Cobalt doped ZnSe and ZnS crystals have been studied to determine their effectiveness for passive Q-switching for 700-800nm spectral range (Alexandrite laser). Samples were prepared using Bridgeman technique for single-step growth of Co doped crystals as well as after growth thermal diffusion of Co in undoped crystals. ZnS:Co:Cr crystals, which have been produced using the Bridgeman technique, show maximum initial absorption coefficients of 17 cm -1 at 725nm. Experimental results are reported on effective thermal diffusion of Co 2+ in ZnSe and ZnS polycrystals and thermal diffusion constants of cobalt ions in ZnSe and ZnS are estimated. The nonlinear saturation properties of cobalt doped ZnSe and ZnS crystals have been investigated experimentally. The induced transparency measurements were performed using electro-optically Q-switched, alexandrite laser radiation at 731, 741, and 778 nm with a pulse duration of about 70 ns. The induced transmission measurements were analyzed using a four-level absorber model and the absorption cross sections have been estimated at both 731nm and 741nm to be 9.5 × 10 -18 cm2 and 8.2 × 10 -18 cm2, respectively. Absorption cross sections calculated from saturation measurements at 4A II--> 4T I(4P) transition are in agreement with results earlier reported for mid-infrared spectral region 4A II--> 4T II of Co 2+ ions. The described Co-doped crystals are very promising as passive Q-switches for alexandrite laser resonators. Co 2+ centers feature high cross section of saturation and their absorption bands are nicely matched to the spectral emission of the tunable alexandrite laser. An efficient ZnS:Co:Cr passive Q-switching of the alexandrite laser cavity was realized with output energy of 15 mJ and 50 ns pulse duration.

  1. Rapid Laser Induced Crystallization of Amorphous NiTi Films Observed by Nanosecond Dynamic Transmission Electron Microscopy (DTEM)

    SciTech Connect

    LaGrange, T; Campbell, G H; Browning, N D; Reed, B W; Grummon, D S

    2010-03-01

    The crystallization processes of the as-deposited, amorphous NiTi thin films have been studied in detail using techniques such as differential scanning calorimetry and, in-situ TEM. The kinetic data have been analyzed in terms of Johnson-Mehl-Avrami-Kolomogrov (JMAK) semi-empirical formula. The kinetic parameters determined from this analysis have been useful in defining process control parameters for tailoring microstructural features and shape memory properties. Due to the commercial push to shrink thin film-based devices, unique processing techniques have been developed using laser-based annealing to spatially control the microstructure evolution down to sub-micron levels. Nanosecond, pulse laser annealing is particularly attractive since it limits the amount of peripheral heating and unwanted microstructural changes to underlying or surrounding material. However, crystallization under pulsed laser irradiation can differ significantly from conventional thermal annealing, e.g., slow heating in a furnace. This is especially true for amorphous NiTi materials and relevant for shape memory thin film based microelectromechanical systems (MEMS) applications. There is little to no data on the crystallization kinetics of NiTi under pulsed laser irradiation, primarily due to the high crystallization rates intrinsic to high temperature annealing and the spatial and temporal resolution limits of standard techniques. However, with the high time and spatial resolution capabilities of the dynamic transmission electron microscope (DTEM) constructed at Lawrence Livermore National Laboratory, the rapid nucleation events occurring from pulsed laser irradiation can be directly observed and nucleation rates can be quantified. This paper briefly explains the DTEM approach and how it used to investigate the pulsed laser induced crystallization processes in NiTi and to determine kinetic parameters.

  2. Laser damage dependence on the size and concentration of precursor defects in KDP crystals: view through differently sized filter pores.

    PubMed

    Wang, Yueliang; Zhao, Yuanan; Xie, Xiaoyi; Hu, Guohang; Yang, Liujiang; Xu, Ziyuan; Shao, Jianda

    2016-04-01

    We investigate the laser-induced damage performance at 1064 nm of potassium dihydrogen phosphate (KDP) crystals grown using filters of different pore sizes. The aim is to explore a novel method for understanding laser-matter interactions with regard to physical parameters affecting the ability of damage precursors to initiate damage. By reducing the pore size of filters in continuous filtration growth, we can improve laser damage resistance. Furthermore, we develop a model based on a Gaussian distribution of precursor thresholds and heat transfer to obtain a size distribution of the precursor defects. Smaller size and/or lower concentration of precursor defects could lead to better damage resistance. PMID:27192280

  3. Passively Q-switched Nd:S-VAP laser with a Cr4+:YAG crystal saturable absorber

    NASA Astrophysics Data System (ADS)

    Shen, Deyuan; Li, Cheng; Song, Jie; Ueda, Ken-ichi

    2000-04-01

    With Cr4+:YAG crystal as the saturable absorber, diode- pumped compact passively Q-switched Nd:S-VAP lasers have been demonstrated using a simple two-mirror linear cavity. When CW pumped with a 1 W high-brightness laser diode, stable laser pulses of duration of 2.9 ns and energy of 13.7 (mu) J are observed with kilohertz repetition rates. The highest peak power of 4.6 kW was obtained at an incident pump power of 904 mW.

  4. Tunable femtosecond laser based on the Nd3+:BaLaGa 3O 7 disordered crystal

    NASA Astrophysics Data System (ADS)

    Agnesi, A.; Pirzio, F.; Tartara, L.; Ugolotti, E.; Zhang, H.; Wang, J.; Yu, H.; Petrov, V.

    2014-03-01

    We demonstrate clear inhomogeneous linewidth broadening for the disordered laser crystal Nd:BaLaGa3O7 (Nd:BLG), which is very promising for the replacement of Nd:glass for ultrafast sources in multiwatt power applications. A Nd:BLG laser oscillator passively mode-locked and pumped by a Ti:sapphire laser generated pulses of 316-fs duration at 1060 nm, whose spectrum completely fills the fluorescence peak at such wavelength. More interestingly, sub-picosecond pulses were smoothly tunable in a 20-nm range, from 1070 to 1090 nm. The shortest pulses achieved were 290 fs long, centered at 1075 nm.

  5. Coherent anti-Stokes Raman scattering imaging with a laser source delivered by a photonic crystal fiber

    PubMed Central

    Wang, Haifeng; Huff, Terry B.; Cheng, Ji-Xin

    2009-01-01

    We demonstrate laser-scanning coherent anti-Stokes Raman scattering (CARS) imaging with two excitation laser beams delivered by a large-mode-area photonic crystal fiber. The group-velocity dispersion and self-phase modulation effects are largely suppressed due to the large mode area of the fiber and the use of pico-second pulses. The fiber delivery preserves the signal level and image spatial resolution well. High-quality images of live spinal cord tissues are acquired using the fiber-delivered laser source. Our method provides a basic platform for developing a flexible and compact CARS imaging system. PMID:16642124

  6. Synthesis of TiO2 nanoscale rods with MHz femtosecond laser irradiation of single crystal surface and characterisation

    NASA Astrophysics Data System (ADS)

    Sivakumar, M.; Tan, Bo; Venkatakrishnan, Krishnan

    2011-06-01

    Growth of nanoscale rods on single crystal rutile TiO2 surface irradiated by MHz pulse repetition rate femtosecond laser in nitrogen environment without a catalyst or template is reported. The rods are of 100 nm in width to 1 micron length. Microraman analysis of the laser irradiated surface shows only a decrease in the intensity of active modes as compared to untreated surface. The growth of TiO2 nanorods can be explained by a method combining nanoparticles formation due to expulsion of molten material from laser irradiated spot and their subsequent growth by vapor-liquid-solid process.

  7. Periodically tapered photonic crystal fibre based strain sensor fabricated by a CO2 laser technique

    NASA Astrophysics Data System (ADS)

    Farrell, Gerald; Bo, Lin; Guan, Chunying; Semenova, Yuliya; Wang, Pengfei

    2014-05-01

    A focused CO2 laser beam has been previously used to successfully fabricate both symmetric and asymmetric long period fiber gratings which have been used for a variety of sensing applications. However fabrication by a CO2 laser beam demands a time consuming laser scanning process which increases the difficulty and cost of fabrication. In this paper a fibre sensor based on a fibre heterostructure with a simple configuration consisting of a series of periodical tapers in a photonic crystal fibre (PCF) sandwiched between two singlemode fibres is proposed and investigated experimentally. The tapers are periodically fabricated along the PCF section using a CO2 laser beam. The proposed fibre heterostructure can be used for strain sensing by measuring the wavelength blueshift of the multimode interference dip of the transmission spectrum as a function of strain. An average stain sensitivity of -68.4 pm/μ ɛ has been experimentally achieved over a microstrain range from 0 to 100 μ ɛ. Assuming in practice that the sensor is interrrogated with a ratiometric power measurement system, then the strain resolution is estimated to be better than 1.18×10-2 microstrain. The mechanisms for refractive index modulation periodically tapered PCF under tensile strain measurements are complex but may be regarded as a combination of stress-relaxation and refractive index perturbations over the length of the tapered PCF induced by strain and by tapering. The proposed fibre strain sensor has the advantage of low temperature sensitivity (average 8.4 pm/°C) and an experimental demonstration of this reduced sensitivity is also presented. The proposed strain sensor benefits from simplicity of fabrication and achieves a competitive sensitivity compared with other existing fibre-optic sensors.

  8. Improving the stability of organosiloxane smectic A liquid crystal random lasers using redox dopants

    NASA Astrophysics Data System (ADS)

    Khan, Ammar A.; Morris, Stephen M.; Gardiner, Damian J.; Qasim, Malik M.; Wilkinson, Timothy D.; Coles, Harry J.

    2015-04-01

    In this paper, we focus on the development of liquid crystal (LC) visible-light scattering devices for random lasers. These light-scattering devices are based upon binary mixtures that consist of an organosiloxane smectic A LC and a wide temperature range nematogen LC. Both the temperature range of the smectic A phase and the dielectric anisotropy of the binary mixture are increased compared with that of the neat organosiloxane compound. In the latter case, the increase in the dielectric anisotropy results in a reduction of the magnitude of the electric field required to induce a clear state. Furthermore, it is found that the electric field threshold continues to decrease with increasing concentration of the nematic compound. For the random laser devices, the Pyrromethene 597 laser dye was added to a mixture that was optimized for scattering and it was found that the absorption properties of the dye becomes unstable in the presence of the electro-hydrodynamic instabilities that are required to generate scattering in the LC cells. This is believed to be due to electro-chemical reactions that occur at the electrodes. To avoid dye degradation and ensure repeatable electro-optic behaviour, a reduction-oxidation (redox) couple is dispersed within the dye-doped binary mixture. It is shown that the addition of redox dopants helps to stabilize the dye in the scattering mixtures, and also increases the long-term repeatability of the scattering behaviour. Finally, we conclude by characterizing the random laser emission of the dye-doped binary mixture and demonstrate improved stability.

  9. Yb:Lu2SiO5 crystal : characterization of the laser emission along the three dielectric axes

    NASA Astrophysics Data System (ADS)

    Toci, Guido; Pirri, Angela; Beitlerova, Alena; Shoji, Yasuhiro; Yoshikawa, Akira; Hybler, Jiri; Nikl, Martin; Vannini, Matteo

    2015-05-01

    Yb:doped Lu2SiO5 (Lutetium orthosilicate, LSO) is an optically biaxial crystal with laser emission in the range 1000- 1100 nm. It features different absorption and emission spectra for polarization along its three dielectric axes. In this work we have characterized the laser emission properties of Yb:LSO along all the three dielectric axis, evidencing differences that can be exploited in the design of ultrafast laser sources. The material was tested in a longitudinally pumped laser cavity. The laser emission efficiency was found similar along all the three dielectric axes, with slope efficiencies around 90% in most cases. Regarding the tuning range, for the most favourable polarization direction we obtained a continuously tunable emission between 993 and 1088 nm (i. e. 95 nm) peaked at 1040 nm. The tuning curves along the three dielectric axes spanned similar ranges but with relevant differences in the shape.

  10. Spatial beam shaping for high-power frequency tripling lasers based on a liquid crystal spatial light modulator

    NASA Astrophysics Data System (ADS)

    Li, Sensen; Wang, Yulei; Lu, Zhiwei; Ding, Lei; Cui, Can; Chen, Yi; Pengyuan, Du; Ba, Dexin; Zheng, Zhenxing; Yuan, Hang; Shi, Lei; Bai, Zhenxu; Liu, Zhaohong; Zhu, Chengyu; Dong, Yongkang; Zhou, Luoxian

    2016-05-01

    We propose and demonstrate a spatial beam shaping method to achieve high-quality near-field for a high-power frequency tripling laser system by using a liquid crystal spatial light modulator (SLM). Considering the nonlinear relationship between the output 3ω intensity and the input 1ω intensity of the frequency conversion system and the transmittance nonuniformity of the whole laser system, we introduce an efficient spatial beam shaping method that improves the output near-field beam quality of frequency tripling laser dramatically. Results show that the near-field peak-to-mean value of the frequency tripling laser improves from 1.83:1 to 1.42:1 after spatial beam shaping within four shots. This method provides effective guidance for spatial beam shaping of high-power frequency tripling laser systems.

  11. SULFIDE MINERALS IN SEDIMENTS

    EPA Science Inventory

    The formation processes of metal sulfides in sediments, especially iron sulfides, have been the subjects of intense scientific research because of linkages to the global biogeochemical cycles of iron, sulfur, carbon, and oxygen. Transition metal sulfides (e.g., NiS, CuS, ZnS, Cd...

  12. Efficient frequency doubling of a pulsed laser diode by use of a periodically poled KTP waveguide crystal with Bragg gratings

    NASA Astrophysics Data System (ADS)

    Rafailov, E. U.; Birkin, D. J. L.; Sibbett, W.; Battle, P.; Fry, T.; Mohatt, D.

    2001-12-01

    Blue light with an average power of as much as 7.5 mW in picosecond pulses has been generated at 486, 488, and 491 nm from a frequency-doubled, nonresonant injection seeded, gain-switched InGaAs/GaAs diode laser by use of a periodically poled KTP waveguide crystal that incorporates a Bragg grating section.

  13. Efficient frequency doubling of a pulsed laser diode by use of a periodically poled KTP waveguide crystal with Bragg gratings.

    PubMed

    Rafailov, E U; Birkin, D J; Sibbett, W; Battle, P; Fry, T; Mohatt, D

    2001-12-15

    Blue light with an average power of as much as 7.5 mW in picosecond pulses has been generated at 486, 488, and 491 nm from a frequency-doubled, nonresonant injection seeded, gain-switched InGaAs/GaAs diode laser by use of a periodically poled KTP waveguide crystal that incorporates a Bragg grating section. PMID:18059745

  14. Simulation and experimental research of x-ray toroidally bent crystal imaging with laser-produced plasma

    NASA Astrophysics Data System (ADS)

    Xinyi, Wang; Shali, Xiao; jian, Lu; Yufen, Wu; Jun, Shi; Jiayu, Qian; Shenye, Liu; Minxi, Wei; Bolun, Chen

    2016-04-01

    Based on the Bragg law and imaging principle of bent crystal, the imaging properties of the monochromic backlighting system with a toroidally bent crystal were studied via ray-tracing simulations and experiments. Comparison experiments with both toroidally and spherically bent crystals using a Cr line as the backlighter were performed, showing that using toroidally bent crystal, a 2D image with the same magnifications in meridional and sagittal directions can be obtained with higher spatial resolution. Experiments with laser-produced plasmas using Mica crystal were carried out on the Shenguang II laser facility. Five laser beams were focused onto a Ti planar target producing a line at 4.75 keV as the backlighter and an image of a metal grid with size of 200 μm  ×  200 μm was recorded with an x-ray image plate. A spatial resolution of 40 μm was demonstrated with a magnification of 3 due to the restriction of the target chamber size. 10 μm spatial resolution might be possible if the detector can be located outside the chamber to enlarge the magnification.

  15. Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal.

    PubMed

    Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I; Wang, Jiyang

    2016-01-01

    With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc.

  16. Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal

    PubMed Central

    Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I.; Wang, Jiyang

    2016-01-01

    With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc. PMID:27461819

  17. Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal

    NASA Astrophysics Data System (ADS)

    Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I.; Wang, Jiyang

    2016-07-01

    With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc.

  18. Efficient high repetition rate electro-optic Q-switched laser with an optically active langasite crystal.

    PubMed

    Ma, Shihui; Yu, Haohai; Zhang, Huaijin; Han, Xuekun; Lu, Qingming; Ma, Changqin; Boughton, Robert I; Wang, Jiyang

    2016-01-01

    With an optically active langasite (LGS) crystal as the electro-optic Q-switch, we demonstrate an efficient Q-switched laser with a repetition rate of 200 kHz. Based on the theoretical analysis of the interaction between optical activity and electro-optic property, the optical activity of the crystal has no influence on the birefringence during Q-switching if the quarter wave plate used was rotated to align with the polarization direction. With a Nd:LuVO4 crystal possessing a large emission cross-section and a short fluorescence lifetime as the gain medium, a stable LGS Q-switched laser was designed with average output power of 4.39 W, corresponding to a slope efficiency of 29.4% and with a minimum pulse width of 5.1 ns. This work represents the highest repetition rate achieved so far in a LGS Q-switched laser and it can provide a practical Q-switched laser with a tunable high repetition rates for many applications, such as materials processing, laser ranging, medicine, military applications, biomacromolecule materials, remote sensing, etc. PMID:27461819

  19. Energy transfer in Tm,Ho:KYW crystal and diode-pumped microchip laser operation.

    PubMed

    Kurilchik, Sergey; Gusakova, Natali; Demesh, Maxim; Yasukevich, Anatol; Kisel, Viktor; Pavlyuk, Anatoly; Kuleshov, Nikolai

    2016-03-21

    An investigation of Tm-Ho energy transfer in Tm(5at.%),Ho(0.4at.%):KYW single crystal by two independent techiques was performed. Based on fluorescence dynamics measurements, energy transfer parameters P71 and P28 for direct (Tm→Ho) and back (Ho→Tm) transfers, respectively, as well as equilibrium constant Θ were evaluated. The obtained results were supported by calculation of microscopic interaction parameters according to the Förster-Dexter theory for a dipole-dipole interaction. Diode-pumped continuous-wave operation of Tm,Ho:KYW microchip laser was demonstrated, for the first time to our knowledge. Maximum output power of 77 mW at 2070 nm was achieved at the fundamental TEM00 mode. PMID:27136836

  20. Development of 3D photonic crystals using sol-gel process for high power laser applications

    NASA Astrophysics Data System (ADS)

    Benoit, F.; Dieudonné, E.; Bertussi, B.; Vallé, K.; Belleville, P.; Mallejac, N.; Enoch, S.; Sanchez, C.

    2015-08-01

    Three-dimensional photonic crystals (PCs) are periodic materials with a modulated refractive index on a length scale close to the light wavelength. This optical property allows the preparation of specific optical components like highly reflective mirrors. Moreover, these structured materials are known to have a high laser-induced damage threshold (LIDT) in the sub-nanosecond range compared to multi-layered dielectric mirrors. This property is obtained because only one high LIDT material (silica) is used. The second material used in the layer stack is replaced by air. In this work, we present the development of 3D PCs with narrow-sized colloidal silica particles, prepared by sol-gel process and deposited with Langmuir-Blodgett technique. Different syntheses routes have been investigated and compared regarding the optical properties of the PCs. Finally a numerical model based on an ideal opal network including defect influence is used to explain these experimental results.

  1. Experiment and simulation of novel liquid crystal plasma mirrors for high contrast, intense laser pulses.

    PubMed

    Poole, P L; Krygier, A; Cochran, G E; Foster, P S; Scott, G G; Wilson, L A; Bailey, J; Bourgeois, N; Hernandez-Gomez, C; Neely, D; Rajeev, P P; Freeman, R R; Schumacher, D W

    2016-01-01

    We describe the first demonstration of plasma mirrors made using freely suspended, ultra-thin films formed dynamically and in-situ. We also present novel particle-in-cell simulations that for the first time incorporate multiphoton ionization and dielectric models that are necessary for describing plasma mirrors. Dielectric plasma mirrors are a crucial component for high intensity laser applications such as ion acceleration and solid target high harmonic generation because they greatly improve pulse contrast. We use the liquid crystal 8CB and introduce an innovative dynamic film formation device that can tune the film thickness so that it acts as its own antireflection coating. Films can be formed at a prolonged, high repetition rate without the need for subsequent realignment. High intensity reflectance above 75% and low-field reflectance below 0.2% are demonstrated, as well as initial ion acceleration experimental results that demonstrate increased ion energy and yield on shots cleaned with these plasma mirrors. PMID:27557592

  2. Experiment and simulation of novel liquid crystal plasma mirrors for high contrast, intense laser pulses

    PubMed Central

    Poole, P. L.; Krygier, A.; Cochran, G. E.; Foster, P. S.; Scott, G. G.; Wilson, L. A.; Bailey, J.; Bourgeois, N.; Hernandez-Gomez, C.; Neely, D.; Rajeev, P. P.; Freeman, R. R.; Schumacher, D. W.

    2016-01-01

    We describe the first demonstration of plasma mirrors made using freely suspended, ultra-thin films formed dynamically and in-situ. We also present novel particle-in-cell simulations that for the first time incorporate multiphoton ionization and dielectric models that are necessary for describing plasma mirrors. Dielectric plasma mirrors are a crucial component for high intensity laser applications such as ion acceleration and solid target high harmonic generation because they greatly improve pulse contrast. We use the liquid crystal 8CB and introduce an innovative dynamic film formation device that can tune the film thickness so that it acts as its own antireflection coating. Films can be formed at a prolonged, high repetition rate without the need for subsequent realignment. High intensity reflectance above 75% and low-field reflectance below 0.2% are demonstrated, as well as initial ion acceleration experimental results that demonstrate increased ion energy and yield on shots cleaned with these plasma mirrors. PMID:27557592

  3. Experiment and simulation of novel liquid crystal plasma mirrors for high contrast, intense laser pulses.

    PubMed

    Poole, P L; Krygier, A; Cochran, G E; Foster, P S; Scott, G G; Wilson, L A; Bailey, J; Bourgeois, N; Hernandez-Gomez, C; Neely, D; Rajeev, P P; Freeman, R R; Schumacher, D W

    2016-08-25

    We describe the first demonstration of plasma mirrors made using freely suspended, ultra-thin films formed dynamically and in-situ. We also present novel particle-in-cell simulations that for the first time incorporate multiphoton ionization and dielectric models that are necessary for describing plasma mirrors. Dielectric plasma mirrors are a crucial component for high intensity laser applications such as ion acceleration and solid target high harmonic generation because they greatly improve pulse contrast. We use the liquid crystal 8CB and introduce an innovative dynamic film formation device that can tune the film thickness so that it acts as its own antireflection coating. Films can be formed at a prolonged, high repetition rate without the need for subsequent realignment. High intensity reflectance above 75% and low-field reflectance below 0.2% are demonstrated, as well as initial ion acceleration experimental results that demonstrate increased ion energy and yield on shots cleaned with these plasma mirrors.

  4. Experiment and simulation of novel liquid crystal plasma mirrors for high contrast, intense laser pulses

    NASA Astrophysics Data System (ADS)

    Poole, P. L.; Krygier, A.; Cochran, G. E.; Foster, P. S.; Scott, G. G.; Wilson, L. A.; Bailey, J.; Bourgeois, N.; Hernandez-Gomez, C.; Neely, D.; Rajeev, P. P.; Freeman, R. R.; Schumacher, D. W.

    2016-08-01

    We describe the first demonstration of plasma mirrors made using freely suspended, ultra-thin films formed dynamically and in-situ. We also present novel particle-in-cell simulations that for the first time incorporate multiphoton ionization and dielectric models that are necessary for describing plasma mirrors. Dielectric plasma mirrors are a crucial component for high intensity laser applications such as ion acceleration and solid target high harmonic generation because they greatly improve pulse contrast. We use the liquid crystal 8CB and introduce an innovative dynamic film formation device that can tune the film thickness so that it acts as its own antireflection coating. Films can be formed at a prolonged, high repetition rate without the need for subsequent realignment. High intensity reflectance above 75% and low-field reflectance below 0.2% are demonstrated, as well as initial ion acceleration experimental results that demonstrate increased ion energy and yield on shots cleaned with these plasma mirrors.

  5. Transient material properties during defect-assisted laser breakdown in deuterated potassium dihydrogen phosphate crystals

    SciTech Connect

    Duchateau, Guillaume; Feit, Michael D.; Demos, Stavros G.

    2014-03-14

    We investigate theoretically the transition from solid dielectric materials to warm solid density plasma during laser-induced breakdown in DKDP crystals (KD{sub 2}PO{sub 4}). Evidence taken from the experimentally measured wavelength dependence of the breakdown threshold suggests that the material excitation mechanisms mainly consist of a sequence of one-photon absorptions between short-lived vibronic defect states spanning the band gap with a quasi-continuum of states. The transition between excitation paths involving different number of photons yields information about the role of temperature in determining the width of the transition and corresponding threshold conduction band density prior to initiation of breakdown. This physical system is well adapted to study a plasma warming up at solid density leading to the so-called warm dense matter.

  6. Pulsed Laser Deposition of VO2 Single Crystal Thin Films on Sapphire Substrates

    NASA Astrophysics Data System (ADS)

    Zhu, Pei-ran; S, Yamamoto; A, Miyashita; H, Naramoto

    1998-12-01

    Thin films of VO2 single-crystalline on (0001) sapphire substrates have been prepared by visible pulsed laser ablation technique. The crystal quality and properties of the films are evaluated through electrical resistance measurement, x-ray diffraction (XRD), and Rutherford-backscattering spectroscopy/channeling (RBS/C) analysis. The dependence of the surface electrical resistance of the films on the temperature shows semiconductor-to-metal transitions with the resistance change of 7 × 103-2 × 104. The hysteresis widths are from less than 1 to 3 K. XRD and RBS/C data reveal that the films prepared in particular conditions are single-crystalline VO2 with the (010) planes parallel to the surface of the sapphire substrate.

  7. Voigt wave investigation in the KGd(WO4)2:Nd biaxial laser crystal

    NASA Astrophysics Data System (ADS)

    Brenier, Alain

    2015-07-01

    We have investigated the Nd3+-doped KGd(WO4)2 biaxial laser crystal for wave propagation directions in the vicinity of the optical axis at wavelengths tunable around 800 nm. The angular absorption distribution was found to be strongly anisotropic. Increasing absorption, the optical axis splits in two new ones able to propagate unchanged a left or a right circularly polarized light and able to propagate a circularly polarized Voigt wave with a linear spatial dependence. The intensities of the transmitted light in different configurations of polarizations were investigated. The angular displacement of the two optical axes versus the absorbed wavelengths was measured and explained with a single oscillator model. The light energy propagation was found distributed inside a crescent-shaped area.

  8. Miniature in-line photonic crystal fiber etalon fabricated by 157 nm laser micromachining.

    PubMed

    Ran, Z L; Rao, Y J; Deng, H Y; Liao, X

    2007-11-01

    A miniature in-line fiber-optic Fabry-Perot etalon is fabricated on a photonic crystal fiber (PCF) by using 157 nm laser micromachining for the first time to our knowledge. Experimental results show that such a PCF-based etalon has an excellent fringe visibility of up to approximately 26 dB due to the mirror-finish quality of the two cavity surfaces inside the PCF. This etalon can be used as an ideal sensor for precise strain measurement under high temperature of up to 800 degrees C. It can also offer some other outstanding advantages, such as fast and easy fabrication, high reproducibility, capacity of mass production, low cost, low temperature-strain cross-sensitivity, and high signal-to-noise ratio. PMID:17975600

  9. Miniature in-line photonic-crystal-fiber etalon fabricated by 157nm laser micromachining

    NASA Astrophysics Data System (ADS)

    Ran, Zeng-ling; Rao, Yun-jiang; Deng, Hong-you; Liao, Xian

    2008-04-01

    A miniature in-line fiber-optic Fabry-Perot etalon sensor is fabricated on a photonic-crystal-fiber (PCF) by using 157nm laser micromachining for the first time to our knowledge. Experimental results show that such a PCF-based etalon sensor has an excellent fringe visibility of up to ~26dB due to the mirror-finish quality of the two cavity surfaces inside the PCF. This etalon sensor can be used as an ideal one for precise strain measurement under high temperature of up to 800°C. It can offer other outstanding advantages, such as fast and easy fabrication, high reproducibility, capacity of mass-production, low-cost, low temperature-strain cross-sensitivity, and high signal-to-noise ratio, etc.

  10. Nonlinear Raman-Nath diffraction of femtosecond laser pulses in a 2D nonlinear photonic crystal.

    PubMed

    Vyunishev, A M; Arkhipkin, V G; Slabko, V V; Baturin, I S; Akhmatkhanov, A R; Shur, V Ya; Chirkin, A S

    2015-09-01

    We study second-harmonic generation (SHG) of femtosecond laser pulses in a rectangular two-dimensional nonlinear photonic crystal (NLPC). Multiple SH beams were observed in the vicinity of the propagation direction of the fundamental beam. It has been verified that the angular positions of these beams obey the conditions of nonlinear Raman-Nath diffraction (NRND). The measured SH spectra of specific NRND orders consist of narrow peaks that experience a high-frequency spectral shift as the order grows. We derive an analytical expression for the process studied and find the theoretical results to be in good agreement with the experimental data. We estimate the enhancement factor of nonlinear Raman-Nath diffraction in 2D NLPC to be 70. PMID:26368697

  11. Photonic crystal heterostructures based on vertical-cavity surface-emitting laser arrays

    NASA Astrophysics Data System (ADS)

    Lundeberg, Lars D. A.; Boiko, Dmitri L.; Kapon, Eli

    The design and analysis of phase-coupled arrays of vertical-cavity surface-emitting lasers (VCSELs) can greatly profit from concepts related to photonic crystals (PhCs). VCSEL-arrays can be modeled as PhCs in which the refractive index varies periodically in the plane normal to the beam propagation direction. The relatively simple implementation of these structures via lithography techniques permits the exploration of complex PhC configurations and the realization of novel spatial-mode-controlled VCSEL array structures. We elaborate here the concept of VCSEL-based PhC heterostructures that permit the control of photonic envelope functions in novel and useful ways. In particular, we discuss envelope function confinement, coupling and switching. Several such heterostructures, implemented using VCSEL arrays employing Bragg mirror patterning, are demonstrated and investigated experimentally.

  12. Crystal growth, optical properties, and continuous-wave laser operation of Nd3+-doped Lu2SiO5 crystal

    NASA Astrophysics Data System (ADS)

    Li, D. Z.; Xu, X. D.; Zhou, D. H.; Xia, C. T.; Wu, F.; Xu, J.; Cong, Z. H.; Zhang, J.; Tang, D. Y.

    2011-01-01

    High quality Nd3+-doped Lu2SiO5 (Nd:LSO) crystal has been grown by the Czochralski technique. The cell parameters were analyzed with X-ray diffraction (XRD). Room temperature absorption and fluorescence spectra and fluorescence lifetime of the Nd:LSO crystal were measured and analyzed. The Judd-Ofelt intensity parameters Ω2,4,6 were obtained to be 2.59, 4.90, and 5.96×10-20 cm2, respectively. The absorption and emission cross sections and the branching ratios were calculated. The peak emission cross section is 5.8 and 6.6×10-20 cm2 at 1075 and 1079 nm, respectively, with full width at half maximum (FWHM) of 2.8 and 5.1 nm in turn. Pumped by a laser diode, a maximum 2.54 W continuous-wave laser output has been obtained with a slope efficiency of 32%. All the results show that this crystal is a promising laser material.

  13. Growth, structural, optical, thermal and laser damage threshold studies of an organic single crystal: 1,3,5 - triphenylbenzene (TPB)

    NASA Astrophysics Data System (ADS)

    Raja, R. Subramaniyan; Babu, G. Anandha; Ramasamy, P.

    2016-05-01

    Good quality single crystals of pure hydrocarbon 1,3,5-Triphenylbenzene (TPB) have been successfully grown using toluene as a solvent using controlled slow cooling solution growth technique. TPB crystallizes in orthorhombic structure with the space group Pna21. The structural perfection of the grown crystal has been analysed by high resolution X-ray diffraction measurements. The range and percentage of the optical transmission are ascertained by recording the UV-vis spectrum. Thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study its thermal properties. Powder second harmonic generation studies were carried out to explore its NLO properties. Laser damage threshold value has been determined using Nd:YAG laser operating at 1064 nm.

  14. Tunable continuous-wave laser at quasi-three-level with a disordered Nd:LGS crystal.

    PubMed

    Wang, Qing; Wei, Zhiyi; Zhang, Yongdong; Zhang, Zhiguo; Yu, Haohai; Zhang, Huaijin; Wang, Jiyang; Gao, Mingwei; Gao, Chunqing; Wang, Zhenlin

    2011-05-15

    A diode-pumped tunable CW Nd(3+):LGS laser at quasi-three-level has been demonstrated. The output power up to 403 mW at the central wavelength of 904 nm was obtained, corresponding to a slope efficiency of 29.7%. Taking advantage of the broad emission spectrum of the disordered crystal Nd:LGS, we tuned the laser wavelength within the spectral range of 899.8 to 906.6 nm with an etalon inserted into the V-type cavity. To the best of our knowledge, it is the first time to obtain a tunable laser based on the (4)F(3/2)-(4)I(9/2) transition of Nd(3+)-doped crystals.

  15. Laser-driven microflow-induced bistable orientation of a nematic liquid crystal in perfluoropolymer-treated unrubbed cells.

    PubMed

    Jampani, V S R; Skarabot, M; Takezoe, H; Muševič, I; Dhara, S

    2013-01-14

    We demonstrate laser-driven microflow-induced orientational change (homeotropic to planar) in a dye-doped nematic liquid crystal. The homeotropic to planar director alignment is achieved in unrubbed cells in the thermal hysteresis range of a discontinuous anchoring reorientation transition due to the local heating by light absorption in dye-doped sample. Various bistable patterns were recorded in the cell by a programmable laser tweezers. The width of the patterns depend on the scanning speed of the tightly focussed laser beam and the minimum width obtained is approximately equal to 0.57μm which is about 35 times smaller than the earlier report in the rubbed cells. We show that the motion of the microbeam spot causes local flow as a result the liquid crystal director is aligned along that direction. PMID:23388965

  16. Two-photon excited fluorescence in the LYB:Eu monoclinic crystal: towards a new scheme of single-beam dual-voxel direct laser writing in crystals.

    PubMed

    Petit, Y; Royon, A; Marquestaut, N; Dussauze, M; Fargues, A; Veber, P; Jubera, V; Cardinal, T; Canioni, L

    2013-01-14

    We report on two-photon excited fluorescence in the oriented Eu(3+)doped LYB monoclinic crystal under femtosecond laser tight focusing. Due to spatial walk-off, the two polarization modes of the incident femtosecond beam simultaneously provide the independent excitation of two distinct focuses, leading to a single-beam dual-voxel nonlinear excitation of fluorescence below material modification threshold. These observations emphasize on the anisotropy of both two-photon absorption as well as fluorescence emission. They demonstrate the localized control of the nonlinear energy deposit, thanks to the adjustment of both the input power and polarization, by properly balancing the injected energy in each voxel. Such approach should be considered for future direct laser writing of waveguides in propagation directions out of the dielectric axes, so as to optimally cope with the highly probable anisotropy of laser-induced material modification thresholds in these crystals. These results open new ways for further potential developments in direct laser writing as the simultaneous inscription of double-line structures for original waveguides processes.

  17. Two-photon excited fluorescence in the LYB:Eu monoclinic crystal: new scheme for single-beam dual-voxel direct laser writing in crystals

    NASA Astrophysics Data System (ADS)

    Petit, Y.; Royon, A.; Marquestaut, N.; Dussauze, M.; Fargues, A.; Veber, P.; Jubera, V.; Cardinal, T.; Canioni, L.

    2013-03-01

    We report on two-photon excited fluorescence in the oriented Eu3+-doped LYB monoclinic crystal under femtosecond laser tight focusing. Due to spatial walk-off, the two polarization modes of the incident femtosecond beam simultaneously provide the independent excitation of two distinct focuses, leading to a single-beam dual-voxel nonlinear excitation of fluorescence below material modification threshold. These observations emphasize on the anisotropy of both two-photon absorption as well as fluorescence emission. They demonstrate the localized control of the nonlinear energy deposit, thanks to the adjustment of both the input power and polarization, by properly balancing the injected energy in each voxel. Such approach should be considered for future direct laser writing of waveguides in propagation directions out of the dielectric axes, so as to optimally cope with the highly probable anisotropy of laser-induced material modification thresholds in these crystals. These results open new ways for further potential developments in direct laser writing as the simultaneous inscription of double-line structures for original waveguides processes.

  18. Numerical study on laser and infrared compatible stealth by forming "hole-digging spectrum" of doped photonic crystal

    NASA Astrophysics Data System (ADS)

    Zhao, Xuanke; Zhao, Qingwu; Zhang, Qinghua; Wang, Lianfen

    2010-10-01

    Compatible stealth of laser and infrared is an urgent demand of modern battlefield, but the demand is ambivalent for conventional materials. As a new type of artificial structure function material, photonic crystals can realize broadband thermal infrared stealth based on its high-reflection photon forbidden band. By forming a "hole-digging" reflection spectrum of doped photonic crystals, high transmittance at military laser wavelength of 1.06μm and 10.6μm can be achieved, so compatible stealth of laser and infrared can be achieved too. In this paper, we selected middle and far infrared-transparent materials, PbTe and Na3AlF6 as high refractive index and low refractive index material respectively, and designed a one-dimensional two-defect-mode photonic crystal based on principles of distributed Bragg reflector microcavity. And then its photon forbidden band was broaden to 1~20μm by constructing two heterojunction photonic crystals. The reflection spectrum and transmission spectrum of the photonic crystals were calculated by characteristic matrix method of thin-film optical theory. The calculation results show that the designed multi-cycle dual-heterojunction photonic crystal has a high spectral reflectance in the near, middle and far infrared band, whose spectral reflectivity is greater than 99% in 1~5μm and 8~14μm infrared bands, and spectral transmittance at 1.06μm and 10.6μm is greater than 96%. This will satisfy the laser and infrared compatible stealth in the near, middle and far infrared bands.

  19. Photonic crystal surface-emitting lasers as a pumping light source for second harmonic generation

    NASA Astrophysics Data System (ADS)

    Watanabe, Akiyoshi; Hirose, Kazuyoshi; Kurosaka, Yoshitaka; Sugiyama, Takahiro; Liang, Yong; Noda, Susumu

    2014-02-01

    Photonic crystal surface emitting lasers (PCSELs) have recently been achieved with both a single spectrum and narrow spot beam pattern under several hundred mW of output power. Even though the high coherence properties of PCSELs are expected to be used for various applications, we have focused on a pumping light source for a wavelength conversion system in this work. We fabricated a 1.06 μm PCSEL with a square lattice 2D photonic crystal in which the lattice period corresponded to the lasing wavelength to obtain green light. The fabricated device had a narrow spot beam pattern of less than 0.5 degrees and a single spectrum at 1068 nm under CW output power of more than 200 mW despite the broad emitting area of 200 × 200 μm2. The wavelength conversion system used single pass second-harmonic generation (SHG) that consisted of only the PCSEL and 50 mm long bulk MgO doped periodically with poled lithium niobate (MgO:PPLN) as a nonlinear medium, i.e., it was a lens-free system. It was important to maintain the high brightness of the pumping light in this system with a single spectrum through the MgO:PPLN. As a result, SHG light was obtained at 534 nm with a narrow spot beam pattern, which followed the beam quality of the PCSEL under CW operation.

  20. Growth and optical properties of Pr3+:KLu(WO4)2 laser crystal: a candidate for red emission laser

    NASA Astrophysics Data System (ADS)

    Yu, Yi; Zhu, Xiurong; Zhang, Xianke; Yuan, Jujun; Yu, Huajun; Kuang, Fangguang; Xiong, Zuzhou; Liao, Jianfei; Zhang, Wen; Wang, Guofu

    2016-06-01

    A Pr3+:KLu(WO4)2 crystal with dimension of 30 × 30 × 15 mm3 was grown in the K2W2O7 flux. A slice was cut from the crystal, and the polarized absorption and fluorescence spectra were measured at room temperature. Based on the J-O theory, the oscillator intensity parameters Ω t ( t = 2, 4, 6), spontaneous emission probabilities and branch ratios were estimated and good results had been obtained. Furthermore, the crystal has a relatively large emission cross-section in the region of 615-630 nm with the highest value of 14.5 × 10-20 cm2, which indicates that the crystal is good for the application in red emission laser. The emission decay time for 1D2 and 3P0 multiplets was discussed. By adapting the I-H model to fit the emission decay curves, the lifetime for 1D2 at 607 nm and 3P0 at 615 nm are 19.72 μs and 8.95 μs, respectively. Then the corresponding fluorescence quantum efficiencies of the two multiplets reach 83.7 % and 87.9 %, respectively. All the studies illustrate that this crystal is potential in red emission laser application.

  1. Imaging X-ray crystal spectrometer for laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Gamboa, E. J.; Montgomery, D. S.; Hall, I. M.; Drake, R. P.

    2011-04-01

    X-ray Thomson scattering (XRTS) is a powerful technique for measuring state variables in dense plasmas. In this paper, we report on the development of a one-dimensional imaging spectrometer for use in characterizing spatially nonuniform, dense plasmas using XRTS. Diffraction of scattered x-rays from a toroidally curved crystal images along a one-dimensional spatial profile while simultaneously spectrally resolving along the other. An imaging spectrometer was fielded at the Trident laser at Los Alamos National Laboratory, yielding a FWHM spatial resolution of < 25 μm, spectral resolution of 4 eV, spectral range of 350 eV, and spatial range of > 3 mm. A geometrical analysis is performed yielding a simple analytical expression for the throughput of the imaging spectrometer scheme. The SHADOW code is used to perform a ray tracing analysis on the spectrometer fielded at the Trident Laser Facility understand the alignment tolerances on the spatial and spectral resolutions. The analytical expression for the throughput was found to agree well with the results from the ray tracing.

  2. Crystal structure of rhodopsin bound to arrestin by femtosecond X-ray laser.

    PubMed

    Kang, Yanyong; Zhou, X Edward; Gao, Xiang; He, Yuanzheng; Liu, Wei; Ishchenko, Andrii; Barty, Anton; White, Thomas A; Yefanov, Oleksandr; Han, Gye Won; Xu, Qingping; de Waal, Parker W; Ke, Jiyuan; Tan, M H Eileen; Zhang, Chenghai; Moeller, Arne; West, Graham M; Pascal, Bruce D; Van Eps, Ned; Caro, Lydia N; Vishnivetskiy, Sergey A; Lee, Regina J; Suino-Powell, Kelly M; Gu, Xin; Pal, Kuntal; Ma, Jinming; Zhi, Xiaoyong; Boutet, Sébastien; Williams, Garth J; Messerschmidt, Marc; Gati, Cornelius; Zatsepin, Nadia A; Wang, Dingjie; James, Daniel; Basu, Shibom; Roy-Chowdhury, Shatabdi; Conrad, Chelsie E; Coe, Jesse; Liu, Haiguang; Lisova, Stella; Kupitz, Christopher; Grotjohann, Ingo; Fromme, Raimund; Jiang, Yi; Tan, Minjia; Yang, Huaiyu; Li, Jun; Wang, Meitian; Zheng, Zhong; Li, Dianfan; Howe, Nicole; Zhao, Yingming; Standfuss, Jörg; Diederichs, Kay; Dong, Yuhui; Potter, Clinton S; Carragher, Bridget; Caffrey, Martin; Jiang, Hualiang; Chapman, Henry N; Spence, John C H; Fromme, Petra; Weierstall, Uwe; Ernst, Oliver P; Katritch, Vsevolod; Gurevich, Vsevolod V; Griffin, Patrick R; Hubbell, Wayne L; Stevens, Raymond C; Cherezov, Vadim; Melcher, Karsten; Xu, H Eric

    2015-07-30

    G-protein-coupled receptors (GPCRs) signal primarily through G proteins or arrestins. Arrestin binding to GPCRs blocks G protein interaction and redirects signalling to numerous G-protein-independent pathways. Here we report the crystal structure of a constitutively active form of human rhodopsin bound to a pre-activated form of the mouse visual arrestin, determined by serial femtosecond X-ray laser crystallography. Together with extensive biochemical and mutagenesis data, the structure reveals an overall architecture of the rhodopsin-arrestin assembly in which rhodopsin uses distinct structural elements, including transmembrane helix 7 and helix 8, to recruit arrestin. Correspondingly, arrestin adopts the pre-activated conformation, with a ∼20° rotation between the amino and carboxy domains, which opens up a cleft in arrestin to accommodate a short helix formed by the second intracellular loop of rhodopsin. This structure provides a basis for understanding GPCR-mediated arrestin-biased signalling and demonstrates the power of X-ray lasers for advancing the frontiers of structural biology.

  3. Crystal structure of rhodopsin bound to arrestin by femtosecond X-ray laser

    SciTech Connect

    Kang, Yanyong; Zhou, X. Edward; Gao, Xiang; He, Yuanzheng; Liu, Wei; Ishchenko, Andrii; Barty, Anton; White, Thomas A.; Yefanov, Oleksandr; Han, Gye Won; Xu, Qingping; de Waal, Parker W.; Ke, Jiyuan; Tan, M. H. Eileen; Zhang, Chenghai; Moeller, Arne; West, Graham M.; Pascal, Bruce D.; Van Eps, Ned; Caro, Lydia N.; Vishnivetskiy, Sergey A.; Lee, Regina J.; Suino-Powell, Kelly M.; Gu, Xin; Pal, Kuntal; Ma, Jinming; Zhi, Xiaoyong; Boutet, Sébastien; Williams, Garth J.; Messerschmidt, Marc; Gati, Cornelius; Zatsepin, Nadia A.; Wang, Dingjie; James, Daniel; Basu, Shibom; Roy-Chowdhury, Shatabdi; Conrad, Chelsie E.; Coe, Jesse; Liu, Haiguang; Lisova, Stella; Kupitz, Christopher; Grotjohann, Ingo; Fromme, Raimund; Jiang, Yi; Tan, Minjia; Yang, Huaiyu; Li, Jun; Wang, Meitian; Zheng, Zhong; Li, Dianfan; Howe, Nicole; Zhao, Yingming; Standfuss, Jörg; Diederichs, Kay; Dong, Yuhui; Potter, Clinton S.; Carragher, Bridget; Caffrey, Martin; Jiang, Hualiang; Chapman, Henry N.; Spence, John C. H.; Fromme, Petra; Weierstall, Uwe; Ernst, Oliver P.; Katritch, Vsevolod; Gurevich, Vsevolod V.; Griffin, Patrick R.; Hubbell, Wayne L.; Stevens, Raymond C.; Cherezov, Vadim; Melcher, Karsten; Xu, H. Eric

    2015-07-22

    G-protein-coupled receptors (GPCRs) signal primarily through G proteins or arrestins. Arrestin binding to GPCRs blocks G protein interaction and redirects signalling to numerous G-protein-independent pathways. Here we report the crystal structure of a constitutively active form of human rhodopsin bound to a pre-activated form of the mouse visual arrestin, determined by serial femtosecond X-ray laser crystallography. Together with extensive biochemical and mutagenesis data, the structure reveals an overall architecture of the rhodopsin-arrestin assembly in which rhodopsin uses distinct structural elements, including transmembrane helix 7 and helix 8, to recruit arrestin. Correspondingly, arrestin adopts the pre-activated conformation, with a ~20° rotation between the amino and carboxy domains, which opens up a cleft in arrestin to accommodate a short helix formed by the second intracellular loop of rhodopsin. In conclusion, this structure provides a basis for understanding GPCR-mediated arrestin-biased signalling and demonstrates the power of X-ray lasers for advancing the frontiers of structural biology.

  4. Crystal structure of rhodopsin bound to arrestin by femtosecond X-ray laser

    DOE PAGES

    Kang, Yanyong; Zhou, X. Edward; Gao, Xiang; He, Yuanzheng; Liu, Wei; Ishchenko, Andrii; Barty, Anton; White, Thomas A.; Yefanov, Oleksandr; Han, Gye Won; et al

    2015-07-22

    G-protein-coupled receptors (GPCRs) signal primarily through G proteins or arrestins. Arrestin binding to GPCRs blocks G protein interaction and redirects signalling to numerous G-protein-independent pathways. Here we report the crystal structure of a constitutively active form of human rhodopsin bound to a pre-activated form of the mouse visual arrestin, determined by serial femtosecond X-ray laser crystallography. Together with extensive biochemical and mutagenesis data, the structure reveals an overall architecture of the rhodopsin-arrestin assembly in which rhodopsin uses distinct structural elements, including transmembrane helix 7 and helix 8, to recruit arrestin. Correspondingly, arrestin adopts the pre-activated conformation, with a ~20° rotationmore » between the amino and carboxy domains, which opens up a cleft in arrestin to accommodate a short helix formed by the second intracellular loop of rhodopsin. In conclusion, this structure provides a basis for understanding GPCR-mediated arrestin-biased signalling and demonstrates the power of X-ray lasers for advancing the frontiers of structural biology.« less

  5. Thermal Stress-Induced Depolarization Loss in Conventional and Panda-Shaped Photonic Crystal Fiber Lasers

    NASA Astrophysics Data System (ADS)

    Mousavi, Seyedeh Laleh; Sabaeian, Mohammad

    2016-07-01

    We report on the modeling of the depolarization loss in the conventional and panda-shaped photonic crystal fiber lasers (PCFLs) due to the self-heating of the fiber, which we call it thermal stress-induced depolarization loss (TSIDL). We first calculated the temperature distribution over the fiber cross sections and then calculated the thermal stresses/strains as a function of heat load per meter. Thermal stress-induced birefringence (TSIB), which is defined as |n x - n y |, in the core and cladding regions was calculated. Finally, TSIDL was calculated for the conventional and panda-shaped PCFLs as a function of fiber length and, respectively, saturated values of 22 and 25 % were obtained which were independent of heat load per meter. For panda-shaped PCFLs, prior to being saturated, an oscillating and damping behavior against the fiber length was seen where in some lengths reached 35 %. The results are close to an experimental value of 30 % reported for a pulsed PCFL (Limpert et al., Opt Express 12:1313-1319, 2004) where the authors reported a degree of polarization of 70 % (i.e., a depolarization of 30 %). The most important result of this work is a saturation behavior of TSIDL at long-enough lengths of the fiber laser which is independent of heat load per meter. To our knowledge, this the first report of TSIBL for PCFLs.

  6. Numerical Study of the Features of Ti-Nb Alloy Crystallization during Selective Laser Sintering

    NASA Astrophysics Data System (ADS)

    Dmitriev, A. I.; Nikonov, A. Y.

    2016-07-01

    The demand for implants with individual shape requires the development of new methods and approaches to their production. The obvious advantages of additive technologies and selective laser sintering are the capabilities to form both the external shape of the product and its internal structure. Recently appeared and attractive from the perspective of biomechanical compatibility are beta alloys of titanium-niobium that have similar mechanical properties to those of cortical bone. This paper studies the processes occurring at different stages of laser sintering using computer simulation on atomic scale. The effect of cooling rate on the resulting crystal structure of Ti-Nb alloy was analysed. Also, the dependence of tensile strength of sintered particles on heating time and cooling rate was studied. It was shown that the main parameter, which determines the adhesive properties of sintered particles, is the contact area obtained during sintering process. The simulation results can both help defining the technological parameters of the process to provide the desired mechanical properties of the resulting products and serve as a necessary basis for calculations on large scale levels in order to study the behaviour of actually used implants.

  7. Combined Hydrodynamic and Diffraction Simulations of Femtosecond X-ray Scattering from Laser-Shocked Crystals

    NASA Astrophysics Data System (ADS)

    Wark, Justin S.; Higginbotham, Andrew; Milathianaki, Despina; Gleason, Arianna

    2014-05-01

    We describe a simple hydrocode based on a two-step integration scheme that models the evolution of elastic and plastic strains in crystals subject to rapid laser-shock loading. By monitoring the elastic strains during plastic flow we track the rotation and spacing of lattice planes within the polycrystalline sample, and can thus predict the signal that would be produced by x-ray diffraction in a variety of experimental geometries. By employing a simple Taylor-Orowan dislocation model we simulate diffraction patterns in a Debye-Scherrer geometry to track the orthogonal strain states within a laser-shocked sample. The yielding rate is approximately matched to those observed in multi-million atom molecular dynamics (MD) simulations, allowing movies to be made of the diffraction images that would be seen in a real experimental geometry, and illustrating the pertinent experimental requirements, including target texture. Judicious choice of geometry allows clear demarcation of the initial elastic response of the target to be made from the subsequent plastic relaxation. We discuss the simulations in the context of the novel experimental capabilities that have recently become available with the advent of 4th generation light sources, which allow single-shot diffraction with sub-100-fsec resolution.

  8. Combined Hydrodynamic and Diffraction Simulations of Femtosecond X-Ray Scattering from Laser-Shocked Crystals

    NASA Astrophysics Data System (ADS)

    Wark, Justin; Higginbotham, Andrew; Milathianaki, Despina; Gleason, Arianna

    2013-06-01

    We describe a simple hydrocode based on a two-step integration scheme that models the evolution of elastic and plastic strains in crystals subject to rapid laser-shock loading. By monitoring the elastic strains during plastic flow we track the rotation and spacing of lattice planes within the polycrystalline sample, and can thus predict the signal that would be produced by X-ray diffraction in a variety of experimental geometries. By employing a simple Taylor-Orowan dislocation model we simulate diffraction patterns from in a Debye-Scherrer geometry to track the orthogonal strain states within a laser-shocked sample. The yielding rate is approximately matched to those observed in multi-million atom MD simulations, allowing movies to be made of the diffraction images that would be seen in a real experimental geometry, and illustrating the pertinent experimental requirements, including target texture. Judicious choice of geometry allows clear demarcation of the initial elastic response of the target to be made from the subsequent plastic relaxation. We discuss the simulations in the context of the novel experimental capabilities that have recently become available with the advent of 4th generation light sources, which allow single-shot diffraction with sub-100-fs resolution.

  9. Crystal structure of rhodopsin bound to arrestin by femtosecond X-ray laser

    PubMed Central

    Kang, Yanyong; Zhou, X. Edward; Gao, Xiang; He, Yuanzheng; Liu, Wei; Ishchenko, Andrii; Barty, Anton; White, Thomas A.; Yefanov, Oleksandr; Han, Gye Won; Xu, Qingping; de Waal, Parker W.; Ke, Jiyuan; Eileen Tan, M. H.; Zhang, Chenghai; Moeller, Arne; West, Graham M.; Pascal, Bruce; Van Eps, Ned; Caro, Lydia N.; Vishnivetskiy, Sergey A.; Lee, Regina J.; Suino-Powell, Kelly M.; Gu, Xin; Pal, Kuntal; Ma, Jinming; Zhi, Xiaoyong; Boutet, Sébastien; Williams, Garth J.; Messerschmidt, Marc; Gati, Cornelius; Zatsepin, Nadia A.; Wang, Dingjie; James, Daniel; Basu, Shibom; Roy-Chowdhury, Shatabdi; Conrad, Chelsie; Coe, Jesse; Liu, Haiguang; Lisova, Stella; Kupitz, Christopher; Grotjohann, Ingo; Fromme, Raimund; Jiang, Yi; Tan, Minjia; Yang, Huaiyu; Li, Jun; Wang, Meitian; Zheng, Zhong; Li, Dianfan; Howe, Nicole; Zhao, Yingming; Standfuss, Jörg; Diederichs, Kay; Dong, Yuhui; Potter, Clinton S; Carragher, Bridget; Caffrey, Martin; Jiang, Hualiang; Chapman, Henry N.; Spence, John C. H.; Fromme, Petra; Weierstall, Uwe; Ernst, Oliver P.; Katritch, Vsevolod; Gurevich, Vsevolod V.; Griffin, Patrick R.; Hubbell, Wayne L.; Stevens, Raymond C.; Cherezov, Vadim; Melcher, Karsten; Xu, H. Eric

    2015-01-01

    G protein-coupled receptors (GPCRs) signal primarily through G proteins or arrestins. Arrestin binding to GPCRs blocks G protein interaction and redirects signaling to numerous G protein-independent pathways. Here we report the crystal structure of a constitutively active form of human rhodopsin bound to a pre-activated form of the mouse visual arrestin, determined by serial femtosecond X-ray laser crystallography. Together with extensive biochemical and mutagenesis data, the structure reveals an overall architecture of the rhodopsin-arrestin assembly, in which rhodopsin uses distinct structural elements, including TM7 and Helix 8 to recruit arrestin. Correspondingly, arrestin adopts the pre-activated conformation, with a ~20° rotation between the N- and C- domains, which opens up a cleft in arrestin to accommodate a short helix formed by the second intracellular loop of rhodopsin. This structure provides a basis for understanding GPCR-mediated arrestin-biased signaling and demonstrates the power of X-ray lasers for advancing the frontiers of structural biology. PMID:26200343

  10. Application of circularly polarized laser radiation for sensing of crystal clouds.

    PubMed

    Balin, Yurii; Kaul, Bruno; Kokhanenko, Grigorii; Winker, David

    2009-04-13

    The application of circularly polarized laser radiation and measurement of the fourth Stokes parameter of scattered radiation considerably reduce the probability of obtaining ambiguous results for radiation depolarization in laser sensing of crystal clouds. The uncertainty arises when cloud particles appear partially oriented by their large diameters along a certain azimuth direction. Approximately in 30% of all cases, the measured depolarization depends noticeably on the orientation of the lidar reference plane with respect to the particle orientation direction. In this case, the corridor of the most probable depolarization values is about 0.1-0.15, but in individual cases, it can be noticeably wider. The present article considers theoretical aspects of this phenomenon and configuration of a lidar capable of measuring the fourth Stokes parameter together with an algorithm of lidar signal processing in the presence of optically thin cloudiness when molecular scattering cannot be neglected. It is demonstrated that the element ?44 of the normalized backscattering phase matrix (BSPM) can be measured. Results of measurements are independent of the presence or absence of azimuthal particle orientation. For sensing in the zenith or nadir, this element characterizes the degree of horizontal orientation of long particle diameters under the action of aerodynamic forces arising during free fall of particles.

  11. Thermal Stress-Induced Depolarization Loss in Conventional and Panda-Shaped Photonic Crystal Fiber Lasers

    NASA Astrophysics Data System (ADS)

    Mousavi, Seyedeh Laleh; Sabaeian, Mohammad

    2016-10-01

    We report on the modeling of the depolarization loss in the conventional and panda-shaped photonic crystal fiber lasers (PCFLs) due to the self-heating of the fiber, which we call it thermal stress-induced depolarization loss (TSIDL). We first calculated the temperature distribution over the fiber cross sections and then calculated the thermal stresses/strains as a function of heat load per meter. Thermal stress-induced birefringence (TSIB), which is defined as | n x - n y |, in the core and cladding regions was calculated. Finally, TSIDL was calculated for the conventional and panda-shaped PCFLs as a function of fiber length and, respectively, saturated values of 22 and 25 % were obtained which were independent of heat load per meter. For panda-shaped PCFLs, prior to being saturated, an oscillating and damping behavior against the fiber length was seen where in some lengths reached 35 %. The results are close to an experimental value of 30 % reported for a pulsed PCFL (Limpert et al., Opt Express 12:1313-1319, 2004) where the authors reported a degree of polarization of 70 % (i.e., a depolarization of 30 %). The most important result of this work is a saturation behavior of TSIDL at long-enough lengths of the fiber laser which is independent of heat load per meter. To our knowledge, this the first report of TSIBL for PCFLs.

  12. Thermal effects of laser illumination on coated quartz crystal microbalance surfaces

    NASA Astrophysics Data System (ADS)

    Keller, Benjamin; Stevens, Keeley; Pan, Liming; Krim, Jacqueline

    2013-03-01

    Prior work on the thermal sensitivity of quartz crystal microbalances (QCM) has shown them to be powerful tools, capable of measuring milli-Kelvin temperature impulses while also presenting a well-understood response to steady state heating. This has been demonstrated for physical contact to the QCM surface via a STM tip with a temperature differential; here we present a novel application wherein a laser is focused onto the coated QCM, thus applying a non-contact thermal pulse. By applying variable length (second to minute) exposures from a laser source we can isolate the thermal shock, time decay and gross heating effects. The system is sensitive to the coating used, showing significant differences in heating for absorbative and reflective coatings. This method is unique in that the QCM measures energy lost into the substrate, unlike standard techniques which focus primarily on material efficiency. This has potential to characterize various coatings used in solar cells and thermal collectors, as well as in photovoltaic materials. Funding provided by NSF DMR.

  13. Crystal structure of rhodopsin bound to arrestin by femtosecond X-ray laser.

    PubMed

    Kang, Yanyong; Zhou, X Edward; Gao, Xiang; He, Yuanzheng; Liu, Wei; Ishchenko, Andrii; Barty, Anton; White, Thomas A; Yefanov, Oleksandr; Han, Gye Won; Xu, Qingping; de Waal, Parker W; Ke, Jiyuan; Tan, M H Eileen; Zhang, Chenghai; Moeller, Arne; West, Graham M; Pascal, Bruce D; Van Eps, Ned; Caro, Lydia N; Vishnivetskiy, Sergey A; Lee, Regina J; Suino-Powell, Kelly M; Gu, Xin; Pal, Kuntal; Ma, Jinming; Zhi, Xiaoyong; Boutet, Sébastien; Williams, Garth J; Messerschmidt, Marc; Gati, Cornelius; Zatsepin, Nadia A; Wang, Dingjie; James, Daniel; Basu, Shibom; Roy-Chowdhury, Shatabdi; Conrad, Chelsie E; Coe, Jesse; Liu, Haiguang; Lisova, Stella; Kupitz, Christopher; Grotjohann, Ingo; Fromme, Raimund; Jiang, Yi; Tan, Minjia; Yang, Huaiyu; Li, Jun; Wang, Meitian; Zheng, Zhong; Li, Dianfan; Howe, Nicole; Zhao, Yingming; Standfuss, Jörg; Diederichs, Kay; Dong, Yuhui; Potter, Clinton S; Carragher, Bridget; Caffrey, Martin; Jiang, Hualiang; Chapman, Henry N; Spence, John C H; Fromme, Petra; Weierstall, Uwe; Ernst, Oliver P; Katritch, Vsevolod; Gurevich, Vsevolod V; Griffin, Patrick R; Hubbell, Wayne L; Stevens, Raymond C; Cherezov, Vadim; Melcher, Karsten; Xu, H Eric

    2015-07-30

    G-protein-coupled receptors (GPCRs) signal primarily through G proteins or arrestins. Arrestin binding to GPCRs blocks G protein interaction and redirects signalling to numerous G-protein-independent pathways. Here we report the crystal structure of a constitutively active form of human rhodopsin bound to a pre-activated form of the mouse visual arrestin, determined by serial femtosecond X-ray laser crystallography. Together with extensive biochemical and mutagenesis data, the structure reveals an overall architecture of the rhodopsin-arrestin assembly in which rhodopsin uses distinct structural elements, including transmembrane helix 7 and helix 8, to recruit arrestin. Correspondingly, arrestin adopts the pre-activated conformation, with a ∼20° rotation between the amino and carboxy domains, which opens up a cleft in arrestin to accommodate a short helix formed by the second intracellular loop of rhodopsin. This structure provides a basis for understanding GPCR-mediated arrestin-biased signalling and demonstrates the power of X-ray lasers for advancing the frontiers of structural biology. PMID:26200343

  14. Visualiser of two-micron laser radiation based on Ho:CaF{sub 2} crystals

    SciTech Connect

    Lyapin, A A; Ryabochkina, P A; Ushakov, S N; Fedorov, P P

    2014-06-30

    The anti-Stokes luminescence spectra of Ho:CaF{sub 2} crystals corresponding to the {sup 5}G{sub 4} → {sup 5}I{sub 8}, {sup 5}G{sub 5} → {sup 5}I{sub 8}, {sup 5}F{sub 3} → {sup 5}I{sub 8}, {sup 5}F{sub 4}({sup 5}S{sub 2}) → {sup 5}I{sub 8}, {sup 5}F{sub 5} → {sup 5}I{sub 8}, {sup 5}S{sub 2} → {sup 5}I{sub 7}, {sup 5}I{sub 4} → {sup 5}I{sub 8}, {sup 5}I{sub 5} → {sup 5}I{sub 8}, {sup 5}F{sub 5} → {sup 5}I{sub 7}, {sup 5}F{sub 3} → {sup 5}I{sub 6}, {sup 5}I{sub 6} → {sup 5}I{sub 8}, {sup 5}F{sub 5} → {sup 5}I{sub 6}, and {sup 5}I{sub 5} → {sup 5}I{sub 7} transitions upon excitation of the {sup 5}I{sub 7} level of Ho{sup 3+} ions are studied. A method for visualisation of IR radiation in the two-micron range using Ho:CaF{sub 2} crystals is proposed. The energy efficiency of conversion of two-micron laser radiation to radiation in the red spectral range 620 – 690 nm by a 1 mol % HoF{sub 3}:CaF{sub 2} crystal is estimated to be no higher than 0.02%. (nonlinear optical phenomena)

  15. Laser drilling of via micro-holes in single-crystal semiconductor substrates using a 1070nm fibre laser with millisecond pulse widths

    NASA Astrophysics Data System (ADS)

    Maclean, Jessica O.; Hodson, Jonathan R.; Voisey, K. T.

    2015-07-01

    Micro-machining of semiconductors is relevant to fabrication challenges within the semiconductor industry. For via holes for solar cells, laser drilling potentially avoids deep plasma etching which requires sophisticated equipment and corrosive, high purity gases. Other applications include backside loading of cold atoms into atom chips and ion traps for quantum physics research, for which holes through the semiconductor substrate are needed. Laser drilling, exploiting the melt ejection material removal mechanism, is used industrially for drilling hard to machine materials such as superalloys. Lasers of the kind used in this work typically form holes with diameters of 100's of microns and depths of a few millimetres in metals. Laser drilling of semiconductors typically uses short pulses of UV or long wavelength IR to achieve holes as small as 50 microns. A combination of material processes occurs including laser absorption, heating, melting, vaporization with vapour and dust particle ejection and resolidification. An investigation using materials with different fundamental material parameters allows the suitability of any given laser for the processing of semiconductors to be determined. We report results on the characterization of via holes drilled using a 2000 W maximum power 1070 nm fibre laser with 1-20 ms pulses using single crystal silicon, gallium arsenide and sapphire. Holes were characterised in cross-section and plan view. Significantly, relatively long pulses were effective even for wide bandgap substrates which are nominally transparent at 1070 nm. Examination of drilled samples revealed holes had been successfully generated in all materials via melt ejection.

  16. Transmissive liquid-crystal device correcting primary coma aberration and astigmatism in laser scanning microscopy

    NASA Astrophysics Data System (ADS)

    Tanabe, Ayano; Hibi, Terumasa; Ipponjima, Sari; Matsumoto, Kenji; Yokoyama, Masafumi; Kurihara, Makoto; Hashimoto, Nobuyuki; Nemoto, Tomomi

    2016-03-01

    Laser scanning microscopy allows 3D cross-sectional imaging inside biospecimens. However, certain aberrations produced can degrade the quality of the resulting images. We previously reported a transmissive liquid-crystal device that could compensate for the predominant spherical aberrations during the observations, particularly in deep regions of the samples. The device, inserted between the objective lens and the microscope revolver, improved the image quality of fixed-mouse-brain slices that were observed using two-photon excitation laser scanning microscopy, which was originally degraded by spherical aberration. In this study, we developed a transmissive device that corrects primary coma aberration and astigmatism, motivated by the fact that these asymmetric aberrations can also often considerably deteriorate image quality, even near the sample surface. The device's performance was evaluated by observing fluorescent beads using single-photon excitation laser scanning microscopy. The fluorescence intensity in the image of the bead under a cover slip tilted in the y-direction was increased by 1.5 times after correction by the device. Furthermore, the y- and z-widths of the imaged bead were reduced to 66% and 65%, respectively. On the other hand, for the imaged bead sucked into a glass capillary in the longitudinal x-direction, correction with the device increased the fluorescence intensity by 2.2 times compared to that of the aberrated image. In addition, the x-, y-, and z-widths of the bead image were reduced to 75%, 53%, and 40%, respectively. Our device successfully corrected several asymmetric aberrations to improve the fluorescent signal and spatial resolution, and might be useful for observing various biospecimens.

  17. Growth, crystalline perfection, optical, thermal, laser damage threshold and electrical characterization of melaminium levulinate monohydrate single crystal

    NASA Astrophysics Data System (ADS)

    Sivakumar, N.; Kanagathara, N.; Bhagavannarayana, G.; Kalainathan, S.; Anbalagan, G.

    2015-09-01

    Equimolar amounts of melamine and levulinic acid results an organic crystal of melaminium levulinate monohydrate (MLM) at room temperature. MLM belongs to a monoclinic crystal structure having P21/c space group which was confirmed by single crystal X-ray diffraction study. Functional groups present in the MLM crystal were identified by FT-IR spectral study. HRXRD study dictates the quality of MLM crystal. UV-visble spectrum of MLM reveals the lower cut-off wavelength of 293 nm with 55% optical transparency and optical band gap was found to be 4.20 eV for the prominent plane (1 0 -1). Refractive indices for the three axes of MLM crystal were found to be nx=2.6, ny=2.4 and nz=2.2 respectively. Further the thermal stability and melting point of MLM crystal were investigated by TG/DTA study. Dielectric permittivity tensor components were estimated for the planes (1 0 -1), (0 1 0) and (1 1 1) respectively. The thermal conductivity of the crystal by Wiedemann-Franz law was found to be 5.99×10-11 W/mK at 70 °C. LDT value (2.84 GW/cm2) of MLM was estimated for laser optical device applications.

  18. Laser-writing inside uniaxially birefringent crystals: fine morphology of ultrashort pulse-induced changes in lithium niobate.

    PubMed

    Karpinski, P; Shvedov, V; Krolikowski, W; Hnatovsky, C

    2016-04-01

    This work presents a detailed analysis of the morphology of femtosecond laser-induced changes in bulk lithium niobate (LiNbO3) - one of the most common host materials in photonics - using second-harmonic generation microscopy and scanning electron microscopy. It is shown that focused linearly polarized near-infrared pulses can produce two or three distinct axially separated regions of modified material, depending on whether the pulse propagation is along or perpendicular to the optical axis. When laser writing in LiNbO3 is conducted in multi-shot irradiation mode and the focused light intensity is kept near the bulk damage threshold, periodic planar nanostructures aligned perpendicular to the laser polarization are produced inside the focal volume. These results provide a new perspective to laser writing in crystalline materials, including the fabrication of passive and active waveguides, photonic crystals, and optical data storage devices. PMID:27137036

  19. Generation of radially and azimuthally polarized beams in Yb:YAG laser with intra-cavity lens and birefringent crystal.

    PubMed

    Thirugnanasambandam, Manasadevi P; Senatsky, Yuri; Ueda, Ken-ichi

    2011-01-31

    We demonstrated the operation of cw diode-pumped Yb:YAG laser in radial or azimuthal polarized (RP or AP) beams using a combination of birefringent uniaxial crystal (c-cut YVO4 or α-BBO) and lens as intra-cavity elements. RP and AP doughnut modes (M2 = 2-2.5, polarization extinction ratio 50-100:1) with output power up to 60 mW were generated. Apart from doughnut modes, RP or AP ring-like off-axis oscillations and multi-ring beams with mixed RP and AP were also observed at the output of this laser scheme. Using intra-cavity short focus lenses with spherical aberrations AP or RP modes of higher orders was obtained. Mechanism of mode selection in the laser is discussed. The large variety of beams with axially symmetric polarizations from the output of the proposed laser scheme may find applications in different fields.

  20. Crystallization of Ge2Sb2Te5 thin films by nano- and femtosecond single laser pulse irradiation

    NASA Astrophysics Data System (ADS)

    Sun, Xinxing; Ehrhardt, Martin; Lotnyk, Andriy; Lorenz, Pierre; Thelander, Erik; Gerlach, Jürgen W.; Smausz, Tomi; Decker, Ulrich; Rauschenbach, Bernd

    2016-06-01

    The amorphous to crystalline phase transformation of Ge2Sb2Te5 (GST) films by UV nanosecond (ns) and femtosecond (fs) single laser pulse irradiation at the same wavelength is compared. Detailed structural information about the phase transformation is collected by x-ray diffraction and high resolution transmission electron microscopy (TEM). The threshold fluences to induce crystallization are determined for both pulse lengths. A large difference between ns and fs pulse irradiation was found regarding the grain size distribution and morphology of the crystallized films. For fs single pulse irradiated GST thin films, columnar grains with a diameter of 20 to 60 nm were obtained as evidenced by cross-sectional TEM analysis. The local atomic arrangement was investigated by high-resolution Cs-corrected scanning TEM. Neither tetrahedral nor off-octahedral positions of Ge-atoms could be observed in the largely defect-free grains. A high optical reflectivity contrast (~25%) between amorphous and completely crystallized GST films was achieved by fs laser irradiation induced at fluences between 13 and 16 mJ/cm2 and by ns laser irradiation induced at fluences between 67 and 130 mJ/cm2. Finally, the fluence dependent increase of the reflectivity is discussed in terms of each photon involved into the crystallization process for ns and fs pulses, respectively.

  1. Random lasing of microporous surface of Cr{sup 2+}:ZnSe crystal induced by femtosecond laser

    SciTech Connect

    Yang, Xianheng; Feng, Guoying E-mail: zhoush@scu.edu.cn; Yao, Ke; Yi, Jiayu; Zhang, Hong; Zhou, Shouhuan E-mail: zhoush@scu.edu.cn

    2015-06-15

    We demonstrate a random lasing emission based on microporous surface of Cr{sup 2+}:ZnSe crystal prepared by femtosecond pulsed laser ablation in high vacuum (below 5 × 10{sup −4} Pa). The scanning electron microscope results show that there are a mass of micropores with an average size of ∼13 μm and smaller ones with ∼1.2 μm on the surface of Cr{sup 2+}:ZnSe crystal. The adjacent micropore spacing of the smaller micropores ranges from 1 μm to 5 μm. Under 1750 nm excitation of Nd:YAG (355 nm) pumped optical parametric oscillator, a random lasing emission with center wavelength of 2350 nm and laser-like threshold of 0.3 mJ/pulse is observed. The emission lifetime of 2350 nm laser reduces from 800 ns to 30 ns as the pump energy increases above threshold. The emission spectra and decay time of smooth surface, groove and microporous surface of Cr{sup 2+}:ZnSe crystal are contrasted. The optional pump wavelength range is from 1500 nm to 1950 nm, which in accordance with the optical absorption property of Cr{sup 2+}:ZnSe crystal. The peak position of excitation spectra is almost identical to the strongest absorption wavelength.

  2. Crystallization of Ge2Sb2Te5 thin films by nano- and femtosecond single laser pulse irradiation

    PubMed Central

    Sun, Xinxing; Ehrhardt, Martin; Lotnyk, Andriy; Lorenz, Pierre; Thelander, Erik; Gerlach, Jürgen W.; Smausz, Tomi; Decker, Ulrich; Rauschenbach, Bernd

    2016-01-01

    The amorphous to crystalline phase transformation of Ge2Sb2Te5 (GST) films by UV nanosecond (ns) and femtosecond (fs) single laser pulse irradiation at the same wavelength is compared. Detailed structural information about the phase transformation is collected by x-ray diffraction and high resolution transmission electron microscopy (TEM). The threshold fluences to induce crystallization are determined for both pulse lengths. A large difference between ns and fs pulse irradiation was found regarding the grain size distribution and morphology of the crystallized films. For fs single pulse irradiated GST thin films, columnar grains with a diameter of 20 to 60 nm were obtained as evidenced by cross-sectional TEM analysis. The local atomic arrangement was investigated by high-resolution Cs-corrected scanning TEM. Neither tetrahedral nor off-octahedral positions of Ge-atoms could be observed in the largely defect-free grains. A high optical reflectivity contrast (~25%) between amorphous and completely crystallized GST films was achieved by fs laser irradiation induced at fluences between 13 and 16 mJ/cm2 and by ns laser irradiation induced at fluences between 67 and 130 mJ/cm2. Finally, the fluence dependent increase of the reflectivity is discussed in terms of each photon involved into the crystallization process for ns and fs pulses, respectively. PMID:27292819

  3. Crystallization of Ge2Sb2Te5 thin films by nano- and femtosecond single laser pulse irradiation.

    PubMed

    Sun, Xinxing; Ehrhardt, Martin; Lotnyk, Andriy; Lorenz, Pierre; Thelander, Erik; Gerlach, Jürgen W; Smausz, Tomi; Decker, Ulrich; Rauschenbach, Bernd

    2016-01-01

    The amorphous to crystalline phase transformation of Ge2Sb2Te5 (GST) films by UV nanosecond (ns) and femtosecond (fs) single laser pulse irradiation at the same wavelength is compared. Detailed structural information about the phase transformation is collected by x-ray diffraction and high resolution transmission electron microscopy (TEM). The threshold fluences to induce crystallization are determined for both pulse lengths. A large difference between ns and fs pulse irradiation was found regarding the grain size distribution and morphology of the crystallized films. For fs single pulse irradiated GST thin films, columnar grains with a diameter of 20 to 60 nm were obtained as evidenced by cross-sectional TEM analysis. The local atomic arrangement was investigated by high-resolution Cs-corrected scanning TEM. Neither tetrahedral nor off-octahedral positions of Ge-atoms could be observed in the largely defect-free grains. A high optical reflectivity contrast (~25%) between amorphous and completely crystallized GST films was achieved by fs laser irradiation induced at fluences between 13 and 16 mJ/cm(2) and by ns laser irradiation induced at fluences between 67 and 130 mJ/cm(2). Finally, the fluence dependent increase of the reflectivity is discussed in terms of each photon involved into the crystallization process for ns and fs pulses, respectively. PMID:27292819

  4. Laser patterning of nonlinear optical Bi2ZnB2O7 crystal lines in glass

    NASA Astrophysics Data System (ADS)

    Komatsu, Takayuki; Inoue, Taisuke; Gao, Xuyi; Shinozaki, Kenji; Honma, Tsuyoshi

    2015-05-01

    Bi2O3-based glasses are very attractive from the viewpoints of low-melting, high refractive index and crystallization, and the research on their glasses and glass-ceramics is at the frontiers of glass science and technology. Nonlinear optical Bi2ZnB2O7 crystal lines with a high orientation were patterned in 3Sm2O3-30.3Bi2O3-33.3ZnO-33.3B2O3 glass by using a laser-induced crystallization technique. It was confirmed from transmission electron microscope observations that crystals were formed in the inside of the glass, i.e., at the beneath of 4 micro-meter from the surface, although lasers (Yb:YVO4 laser with a wavelength of 1080 nm) were focused at the glass surface. A new potential for optical device applications was added in Bi2O3-based glasses from the present study.

  5. About the luminescence properties of YAG:Nd, Ce and YAG:Nd single crystals and their relation to laser properties

    NASA Astrophysics Data System (ADS)

    Mares, Jiri A.; Kubelka, Jiri; Kvapil, Jiri

    1986-09-01

    Laser excited luminescence studies of various YAG:Nd, Ce and YAG:Nd (with an excess of yttrium) single crystals together with a testing of laser properties of rods made from the same crystals have been investigated in this paper. It was observed that laser pulse energies increase with increasing halfwidths of the luminescence spectral bands. This dependence and other observations indicate that local structure changes or Nd(3+) nonequivalent centers are present in the studied crystals. Various mechanisms leading to the formation of Nd(3+) nonequivalent centers are discussed and it seems that the more probable mechanism is oxygen segregation and diffusion.

  6. Platinum-scatterer-based random lasers from dye-doped polymer-dispersed liquid crystals in capillary tubes.

    PubMed

    Wang, Jianlong; Zhang, Yating; Cao, Mingxuan; Song, Xiaoxian; Che, Yongli; Zhang, Haiting; Zhang, Heng; Yao, Jianquan

    2016-07-20

    The resonance characteristics of platinum-scatter-based random lasers from dye-doped polymer-dispersed liquid crystals (DDPDLCs) in capillary tubes were researched for the first time, to the best of our knowledge. After adding platinum nanoparticles (Pt NPs) into the liquid crystal mixtures, the emission spectra of DDPDLCs revealed a lower lasing threshold in comparison with those of DDPDLCs without Pt NPs due to light scattering of liquid crystal droplets and the local field enhancement around Pt NPs. Furthermore, the full width at half-maximum (FWHM) and the lasing threshold were determined by the doping density of the Pt NPs. The threshold was decreased by about half from 17.5  μJ/pulse to 8.7  μJ/pulse on the condition that around 1.0 wt. % was the optimum concentration of Pt NPs doped into the DDPDLCs. The FWHM of the peaks sharply decreased to 0.1 nm. Our work provides an extremely simple method to enhance random lasers from DDPDLCs doped with Pt NPs, and it has potential applications in random fiber lasers or laser displays.

  7. Platinum-scatterer-based random lasers from dye-doped polymer-dispersed liquid crystals in capillary tubes.

    PubMed

    Wang, Jianlong; Zhang, Yating; Cao, Mingxuan; Song, Xiaoxian; Che, Yongli; Zhang, Haiting; Zhang, Heng; Yao, Jianquan

    2016-07-20

    The resonance characteristics of platinum-scatter-based random lasers from dye-doped polymer-dispersed liquid crystals (DDPDLCs) in capillary tubes were researched for the first time, to the best of our knowledge. After adding platinum nanoparticles (Pt NPs) into the liquid crystal mixtures, the emission spectra of DDPDLCs revealed a lower lasing threshold in comparison with those of DDPDLCs without Pt NPs due to light scattering of liquid crystal droplets and the local field enhancement around Pt NPs. Furthermore, the full width at half-maximum (FWHM) and the lasing threshold were determined by the doping density of the Pt NPs. The threshold was decreased by about half from 17.5  μJ/pulse to 8.7  μJ/pulse on the condition that around 1.0 wt. % was the optimum concentration of Pt NPs doped into the DDPDLCs. The FWHM of the peaks sharply decreased to 0.1 nm. Our work provides an extremely simple method to enhance random lasers from DDPDLCs doped with Pt NPs, and it has potential applications in random fiber lasers or laser displays. PMID:27463926

  8. Phase Engineering of 2D Tin Sulfides.

    PubMed

    Mutlu, Zafer; Wu, Ryan J; Wickramaratne, Darshana; Shahrezaei, Sina; Liu, Chueh; Temiz, Selcuk; Patalano, Andrew; Ozkan, Mihrimah; Lake, Roger K; Mkhoyan, K A; Ozkan, Cengiz S

    2016-06-01

    Tin sulfides can exist in a variety of phases and polytypes due to the different oxidation states of Sn. A subset of these phases and polytypes take the form of layered 2D structures that give rise to a wide host of electronic and optical properties. Hence, achieving control over the phase, polytype, and thickness of tin sulfides is necessary to utilize this wide range of properties exhibited by the compound. This study reports on phase-selective growth of both hexagonal tin (IV) sulfide SnS2 and orthorhombic tin (II) sulfide SnS crystals with diameters of over tens of microns on SiO2 substrates through atmospheric pressure vapor-phase method in a conventional horizontal quartz tube furnace with SnO2 and S powders as the source materials. Detailed characterization of each phase of tin sulfide crystals is performed using various microscopy and spectroscopy methods, and the results are corroborated by ab initio density functional theory calculations. PMID:27099950

  9. Phase Engineering of 2D Tin Sulfides.

    PubMed

    Mutlu, Zafer; Wu, Ryan J; Wickramaratne, Darshana; Shahrezaei, Sina; Liu, Chueh; Temiz, Selcuk; Patalano, Andrew; Ozkan, Mihrimah; Lake, Roger K; Mkhoyan, K A; Ozkan, Cengiz S

    2016-06-01

    Tin sulfides can exist in a variety of phases and polytypes due to the different oxidation states of Sn. A subset of these phases and polytypes take the form of layered 2D structures that give rise to a wide host of electronic and optical properties. Hence, achieving control over the phase, polytype, and thickness of tin sulfides is necessary to utilize this wide range of properties exhibited by the compound. This study reports on phase-selective growth of both hexagonal tin (IV) sulfide SnS2 and orthorhombic tin (II) sulfide SnS crystals with diameters of over tens of microns on SiO2 substrates through atmospheric pressure vapor-phase method in a conventional horizontal quartz tube furnace with SnO2 and S powders as the source materials. Detailed characterization of each phase of tin sulfide crystals is performed using various microscopy and spectroscopy methods, and the results are corroborated by ab initio density functional theory calculations.

  10. High-power diode-pumped passively Q-switched Nd:S-VAP laser with Cr4+:YAG crystal saturable absorber

    NASA Astrophysics Data System (ADS)

    Shen, Deyuan; Tang, Ding Y.; Tam, Siu Chung; Ueda, Ken-ichi

    2001-10-01

    Neodymium-doped strontium fluoro-vanadate is a favorable laser material for diode-pumped, compact, and passively Q-switched lasers. We have constructed a high power passively Q-switched Nd:S-VAP laser with a fiber coupled 10 W laser diode pumping. To avoid severe thermal deposition and thermal induced crystal fracture, several measures have been taken in the laser design. With a Cr4+:YAG of initial transmission of 80%, stable laser pulses of duration of 3 ns, energy of 45 micro-joule and repetition rate of 23 kHz are obtained at an incident pump power of 7.75 W.

  11. The interaction of 193-nm excimer laser radiation with single-crystal zinc oxide: The generation of atomic Zn line emission at laser fluences below breakdown

    SciTech Connect

    Khan, Enamul H.; Langford, S. C.; Dickinson, J. T.; Boatner, L. A.

    2013-08-28

    The production of gas phase atomic and ionic line spectra accompanying the high laser fluence irradiation of solid surfaces is well known and is most often due to the production and interaction of high densities of atoms, ions, and electrons generated from laser-induced breakdown. The resulting plasma expands and moves rapidly away from the irradiated spot and is accompanied by intense emission of light. This type of “plume” is well studied and is frequently exploited in the technique of chemical analysis known as laser induced breakdown spectroscopy. Here, we describe a similar but weaker emission of light generated in vacuum by the laser irradiation of single crystal ZnO at fluences well below breakdown; this emission consists entirely of optical line emission from excited atomic Zn. We compare the properties of the resulting laser-generated gas-phase light emission (above and below breakdown) and describe a mechanism for the production of the low-fluence optical emission resulting from a fortuitous choice of material and laser wavelength.

  12. Laser performance of diode-pumped Nd, Y-codoped CaF 2-SrF 2 mixed crystal

    NASA Astrophysics Data System (ADS)

    Liu, J.; Fan, M. W.; Su, L. B.; Jiang, D. P.; Ma, F. K.; Zhang, Q.; Xu, J.

    2014-03-01

    A disordered Nd, Y-codoped CaF2-SrF2 mixed crystal was obtained by the temperature gradient technique (TGT). The absorption and fluorescence spectra of the crystal were measured at room temperature. Diode-pumped continuous-wave (CW) and Q-switched laser operations were demonstrated at 1056 nm with a 0.65 at.% Nd, 10 at.% Y-codoped crystal, for the first time to our knowledge. The CW output power of 724 mW was obtained in a compact linear cavity. Also the Q-switched pulse characteristics of Nd, Y:CaF2-SrF2 laser crystal were reported based on Cr4+:YAG saturable absorbers in a folded cavity. The shortest pulse width of 110 ns and the highest peak power of 383 W were obtained when the initial transmission of the Cr4+:YAG crystals was 90%. The dependence of the operational parameters on the pump power was also investigated experimentally.

  13. Liquid crystal films as on-demand, variable thickness (50–5000 nm) targets for intense lasers

    SciTech Connect

    Poole, P. L. Andereck, C. D.; Schumacher, D. W.; Daskalova, R. L.; Feister, S.; George, K. M.; Willis, C.; Akli, K. U.; Chowdhury, E. A.

    2014-06-15

    We have developed a new type of target for intense laser-matter experiments that offers significant advantages over those currently in use. The targets consist of a liquid crystal film freely suspended within a metal frame. They can be formed rapidly on-demand with thicknesses ranging from nanometers to micrometers, where the particular value is determined by the liquid crystal temperature and initial volume as well as by the frame geometry. The liquid crystal used for this work, 8CB (4′-octyl-4-cyanobiphenyl), has a vapor pressure below 10{sup −6} Torr, so films made at atmospheric pressure maintain their initial thickness after pumping to high vacuum. Additionally, the volume per film is such that each target costs significantly less than one cent to produce. The mechanism of film formation and relevant physics of liquid crystals are described, as well as ion acceleration data from the first shots on liquid crystal film targets at the Ohio State University Scarlet laser facility.

  14. Laser-driven 6-16 keV x-ray imaging and backlighting with spherical crystals

    NASA Astrophysics Data System (ADS)

    Schollmeier, M.; Rambo, P. K.; Schwarz, J.; Smith, I. C.; Porter, J. L.

    2014-10-01

    Laser-driven x-ray self-emission imaging or backlighting of High Energy Density Physics experiments requires brilliant sources with keV energies and x-ray crystal imagers with high spatial resolution of about 10 μ m. Spherically curved crystals provide the required resolution when operated at near-normal incidence, which minimizes image aberrations due to astigmatism. However, this restriction dramatically limits the range of suitable crystal and spectral line combinations. We present a survey of crystals and spectral lines for x-ray backlighting and self-emission imaging with energies between 6 and 16 keV. Ray-tracing simulations including crystal rocking curves have been performed to predict image brightness and spatial resolution. Results have been benchmarked to experimental data using both Sandia's 4 kJ, ns Z-Beamlet and 200 J, ps Z-Petawatt laser systems. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000. SAND NO. 2014-15552A.

  15. Thermal, spectroscopic and laser properties of Nd3+ in gadolinium scandium gallium garnet crystal produced by optical floating zone method

    NASA Astrophysics Data System (ADS)

    Tian, Li; Wang, Shuxian; Wu, Kui; Wang, Baolin; Yu, Haohai; Zhang, Huaijin; Cai, Huaqiang; Huang, Hui

    2013-12-01

    A neodymium-doped gadolinium scandium gallium garnet (Nd:GSGG) single crystal with dimensions of Φ 5 × 20 mm2 has been grown by means of optical floating zone (OFZ). X-ray powder diffraction (XRPD) result shows that the as-grown Nd:GSGG crystal possesses a cubic structure with space group Ia3d and a cell parameter of a = 1.2561 nm. Effective elemental segregation coefficients of the Nd:GSGG as-grown crystal were calculated by using X-ray fluorescence (XRF). The thermal properties of the Nd:GSGG crystal were systematically studied by measuring the specific heat, thermal expansion and thermal diffusion coefficient, and the thermal conductivity of this crystal was calculated. The absorption and luminescence spectra of Nd:GSGG were measured at room temperature (RT). By using the Judd-Ofelt (J-O) theory, the theoretical radiative lifetime was calculated and compared with the experimental result. Continuous wave (CW) laser performance was achieved with the Nd:GSGG at the wavelength of 1062 nm when it was pumped by a laser diode (LD). A maximum output power of 0.792 W at 1062 nm was obtained with a slope efficiency of 11.89% under a pump power of 7.36 W, and an optical-optical conversion efficiency of 11.72%.

  16. Lasers.

    ERIC Educational Resources Information Center

    Schewe, Phillip F.

    1981-01-01

    Examines the nature of laser light. Topics include: (1) production and characteristics of laser light; (2) nine types of lasers; (3) five laser techniques including holography; (4) laser spectroscopy; and (5) laser fusion and other applications. (SK)

  17. Spatially selected synthesis of LaF{sub 3} and Er{sup 3+}-doped CaF{sub 2} crystals in oxyfluoride glasses by laser-induced crystallization

    SciTech Connect

    Kusatsugu, M.; Kanno, M.; Honma, T.; Komatsu, T.

    2008-05-15

    Oxyfluoride glasses with a small amount of NiO are prepared using a conventional melt quenching technique, and the spatially selected crystallization of LaF{sub 3} and CaF{sub 2} crystals is induced on the glass surface by irradiations of continuous wave lasers with a wavelength of {lambda}=1064 or 1080 nm. Dots and lines including LaF{sub 3} crystals are patterned by heat-assisted (300 deg. C) laser irradiations ({lambda}=1064 nm) with a power of P=1 W and an irradiation time of 10 s for dots and a scanning speed of S=5 {mu}m/s for lines. Lines consisting of CaF{sub 2} crystals are also patterned in an ErF{sub 3}-doped oxyfluoride glass by laser irradiations ({lambda}=1080 nm) with a power of P=1.7 W and a scanning speed of S=2 {mu}m/s, and the incorporation of Er{sup 3+} ions into CaF{sub 2} crystals is confirmed from micro-photoluminescence spectrum measurements. It is proposed that the lines patterned by laser irradiations in this study are consisted of the composite of LaF{sub 3} or CaF{sub 2} nanocrystals and SiO{sub 2}-based oxide glassy phase. It is demonstrated that a combination of Ni{sup 2+}-dopings and laser irradiations is effective in spatially selected local crystallizations of fluorides in oxyfluoride glasses. - Graphical abstract: This figure shows the polarization optical and confocal scanning laser micrographs for lines obtained by laser irradiations with a laser power of P=1.7 W and a scanning speed of S=2 {mu}m/s in an oxyfluoride glass. It is proposed that the line consists of the composite of CaF{sub 2} nanocrystals and oxide glassy phase. This is the first demonstration on the patterning of fluoride crystals in glass by laser irradiations.

  18. Laser response of a quartz crystal microbalance: frequency changes induced by light irradiation in the air phase.

    PubMed

    Kawasaki, Takayoshi; Mochida, Tetsuhiro; Katada, Jun-ichi; Okahata, Yoshio

    2009-09-01

    A weak laser irradiation (523-785 nm, 5-60 mW) onto an Au electrode surface of a 27-MHz quartz crystal microbalance (QCM) caused a frequency increase (a mass decrease) in the air phase. These frequency changes depended on the wavelength of the irradiated laser in the order of 523 nm > 636 nm > 785 nm, which corresponds to the light absorbance of the Au electrode of the QCM. The laser response increased linearly with increasing laser power (5-60 mW). In addition, the laser response showed a maximum at the incidence angle of 72 degrees when the P-polarized 636 nm laser was irradiated on the Au surface, due to the evanescent effect. These laser responses were also observed in the humid air of H2O, D2O, and in the vapors of various alcohols. Based on these findings, the observed frequency increase (mass decrease) can be explained by the photo-induced reversible desorption of water molecules from the Au electrode surface of the QCM due to the interfacial property changes.

  19. Fabrication of microchannels in single-crystal GaN by wet-chemical-assisted femtosecond-laser ablation

    NASA Astrophysics Data System (ADS)

    Nakashima, Seisuke; Sugioka, Koji; Midorikawa, Katsumi

    2009-09-01

    We investigated micro- and nano-fabrication of wide band-gap semiconductor gallium nitride (GaN) using a femtosecond (fs) laser. Nanoscale craters were successfully formed by wet-chemical-assisted fs-laser ablation, in which the laser beam is focused onto a single-crystal GaN substrate in a hydrochloric acid (HCl) solution. This allows efficient removal of ablation debris produced by chemical reactions during ablation, resulting in high-quality ablation. However, a two-step processing method involving irradiation by a fs-laser beam in air followed by wet etching, distorts the shape of the crater because of residual debris. The threshold fluence for wet-chemical-assisted fs-laser ablation is lower than that for fs-laser ablation in air, which is advantageous for improving fabrication resolution since it reduces thermal effects. We have fabricated craters as small as 510 nm by using a high numerical aperture (NA) objective lens with an NA of 0.73. Furthermore, we have formed three-dimensional hollow microchannels in GaN by fs-laser direct-writing in HCl solution.

  20. Investigation of laser-fired point contacts on KOH structured laser-crystallized silicon by conductive atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Gref, Orman; Weizman, Moshe; Rhein, Holger; Gabriel, Onno; Gernert, Ulrich; Schlatmann, Rutger; Boit, Christian; Friedrich, Felice

    2016-06-01

    A conductive atomic force microscope is used to study the local topography and conductivity of laser-fired aluminum contacts on KOH-structured multicrystalline silicon surfaces. A significant increase in conductivity is observed in the laser-affected area. The area size and spatial uniformity of this enhanced conductivity depends on the laser energy fluence. The laser-affected area shows three ring-shaped regimes of different conductance depending on the local aluminum and oxygen concentration. Finally, it was found that the topographic surface structure determined by the silicon grain orientation does not significantly affect the laser-firing process.

  1. Micromachining of liquid crystal polymer film with frequency converted diode-pumped Nd:YVO4 laser

    NASA Astrophysics Data System (ADS)

    Li, Mingwei; Hix, Ken; Dosser, Larry R.; Hartke, Kevin; Blackshire, Jim

    2003-07-01

    Liquid crystal polymer (LCP) is a new and innovative material being used as an alternative to polyimide in the flexible circuit industry. LCP has many intrinsic benefits over polyimide including lower moisture absorption and improved dimensional stability. However, LCP is very resistant to chemical milling or etching. As a result, other methods for processing the material are being investigated including laser micromachining. In this paper, three frequency converted diode-pumped solid-state (DPSS) Nd:YVO4 lasers at 355 nm were used to micromachine a LCP film and a copper/LCP laminate. Of them, two are Q-switched lasers operating in the nanosecond regime and the other a mode-locked laser in the picosecond regime. The Q-switched lasers can be operated at pulse repetition rates of 1 to 300 kHz while the mode-locked system is operated at 80 MHz. The micromachining experiments consisted of cutting the 50 μm thick LCP film, cutting the 18 μm thick copper on the film, and drilling micro-vias through both the copper coating and the film substrate. The laser/material interactions and processing speeds were studied and compared. The results show that, compared to polyimide film of the same thickness, LCP film can be more efficiently processed by laser micromachining. In addition, each laser has a unique advantage in processing LCP based flexible circuit materials. The Q-switched lasers are more capable of processing the copper coating while the mode-locked laser can cut LCP film faster with the smallest kerf width.

  2. Diode-laser-pumped high efficiency continuous-wave operation at 912 nm laser in Nd:GdVO4 crystal

    NASA Astrophysics Data System (ADS)

    Yu, X.; Chen, F.; Gao, J.; Li, X. D.; Yan, R. P.; Zhang, K.; Yu, J. H.; Zhang, Z. H.

    2009-01-01

    High efficiency operation on continuous-wave (cw) 912 nm laser at room temperature in Nd:GdVO4 crystal pumped by 808 nm diode-laser is reported in this letter. The maximum output power of 8.0 W was obtained at the incident un-polarized pump power of 47.0 W, giving the corresponding optical-to-optical conversion efficiency of 17.0% and the average slope efficiency of 22.9%. Further tests show that the lasing threshold is reduced and the efficiency is increased evidently when using the π-polarized 808 nm pump source. 4.8 W 912 nm laser was achieved at the polarized pump power of 21.8 W, optical-to-optical conversion efficiency is increased to 22.0% and average slope efficiency is up to 33.6%.

  3. Investigation of Cr:Tm:Er:YAG laser crystals in a resonator with various degrees of spectral selectivity.

    PubMed

    Mochalov, I V; Petrovskii, G T; Sandulenko, A V; Sandulenko, V A; Cervantes, M; Terpugov, V S

    1997-06-20

    It has been established that Tm(3+) ions do not prevent multiple-wavelength oscillation in Cr:Tm:Er:YAG laser crystals inserted inside of the completely nonselective mirror resonator. The output mirror spectral selectivity needed for single-wavelength oscillation at 2.697 mum for a considerable excess of pumping energy over the threshold has been determined experimentally. It has been shown that Tm(3+) optimum concentration in the crystals could be determined correctly in the described resonator scheme. PMID:18253431

  4. Femtosecond laser direct writing of large-area two-dimensional metallic photonic crystal structures on tungsten surfaces.

    PubMed

    Qiao, Hongzhen; Yang, Jianjun; Wang, Fei; Yang, Yang; Sun, Julong

    2015-10-01

    Metallic photonic crystals (MPCs) and metamaterials operating in the visible spectrum are required for high-temperature nanophotonics, but they are often difficult to construct. This study demonstrates a new approach to directly write two-dimensional (2D) MPCs on tungsten surfaces through the cylindrical focusing of two collinear femtosecond laser beams with certain temporal delays and orthogonal linear polarizations. Results are physically attributed to the laser-induced transient crossed temperature grating patterns and tempo-spatial thermal correlations. Optical properties of the fabricated MPCs are characterized. Such a simple and efficient technique can be used to fabricate large-area, 2D microstructures on metal surfaces for potential applications.

  5. 1.083 μm laser operation in Nd,Mg:LiTaO3 crystal

    NASA Astrophysics Data System (ADS)

    Hu, P. C.; Hang, Y.; Li, R.; Gong, J.; Yin, J. G.; Zhao, C. C.; He, X. M.; Yu, T.; Zhang, L. H.; Chen, W. B.; Zhu, Y. Y.

    2011-10-01

    Nd,Mg:LiTaO3 single crystal with high optical quality was grown by Czochralski technique. Absorption and fluorescence spectra were investigated. The peak absorption cross section at 806.5 nm and peak emission cross section at 1091 nm are 6.81×10-20 and 3.28×10-20 cm2, respectively. The fluorescence lifetime was measured to be 129 μs. With a laser-diode as the pump source, a maximum 375 mW continuous-wave laser output at 1083 nm has been obtained with a slope efficiency of 7.2% with respect to the pump power.

  6. Self-organized homo-epitaxial growth in nonlinear optical BaAlBO3F2 crystal crossing lines patterned by laser in glass

    NASA Astrophysics Data System (ADS)

    Shinozaki, K.; Abe, S.; Honma, T.; Komatsu, T.

    2015-11-01

    Crystallization processing of glasses is important as a novel technique for the development of new optical materials, and laser-induced crystallization provides a new challenge in science and technology of materials. Nonlinear optical BaAlBO3F2 crystal lines with crossing, bending, and spiral shapes were patterned at the surface of 2NiO-49BaF2-24.5Al2O3-24.5B2O3 (mol%) and 2.9NiO-48.5BaF2-24.3Al2O3-24.3B2O3 (mol%) glasses by laser irradiation (Yb:YVO4 laser with a wavelength of 1080 nm) and the orientation state of BaAlBO3F2 crystals was examined from birefringence image observations. The birefringence images indicate that the growth of highly c-axis oriented BaAlBO3F2 crystals follows along the laser scanning direction even if the laser scanning direction changes, and in particular the direction of the c-axis of BaAlBO3F2 crystals changes gradually at the crossing and bending points. The model of "self-organized homo-epitaxial growth" is proposed for the crystal orientation at the crossing and bending points, as a new crystal growth science and engineering beyond the wise providence of nature.

  7. High power single-frequency and frequency-doubled laser with active compensation for the thermal lens effect of terbium gallium garnet crystal.

    PubMed

    Yin, Qiwei; Lu, Huadong; Su, Jing; Peng, Kunchi

    2016-05-01

    The thermal lens effect of terbium gallium garnet (TGG) crystal in a high power single-frequency laser severely limits the output power and the beam quality of the laser. By inserting a potassium dideuterium phosphate (DKDP) slice with negative thermo-optical coefficient into the laser resonator, the harmful influence of the thermal lens effect of the TGG crystal can be effectively mitigated. Using this method, the stable range of the laser is broadened, the bistability phenomenon of the laser during the process of changing the pump power is completely eliminated, the highest output power of an all-solid-state continuous-wave intracavity-frequency-doubling single-frequency laser at 532 nm is enhanced to 30.2 W, and the beam quality of the laser is significantly improved. PMID:27128067

  8. Generation of 3.5 W of diffraction-limited green light from SHG of a single tapered diode laser in a cascade of nonlinear crystals

    NASA Astrophysics Data System (ADS)

    Hansen, Anders K.; Jensen, Ole B.; Sumpf, Bernd; Erbert, Götz; Unterhuber, Angelika; Drexler, Wolfgang; Andersen, Peter E.; Petersen, Paul Michael

    2014-02-01

    Many applications, e.g., within biomedicine stand to benefit greatly from the development of diode laser-based multi- Watt efficient compact green laser sources. The low power of existing diode lasers in the green area (about 100 mW) means that the most promising approach remains nonlinear frequency conversion of infrared tapered diode lasers. Here, we describe the generation of 3.5 W of diffraction-limited green light from SHG of a single tapered diode laser, itself yielding 10 W at 1063 nm. This SHG is performed in single pass through a cascade of two PPMgO:LN crystals with re-focusing and dispersion compensating optics between the two nonlinear crystals. In the low-power limit, such a cascade of two crystals has the theoretical potential for generation of four times as much power as a single crystal without adding significantly to the complexity of the system. The experimentally achieved power of 3.5 W corresponds to a power enhancement greater than 2 compared to SHG in each of the crystals individually and is the highest visible output power generated by frequency conversion of a single diode laser. Such laser sources provide the necessary pump power for biophotonics applications, such as optical coherence tomography or multimodal imaging devices, e.g., FTCARS-OCT, based on a strongly pumped ultrafast Ti:Sapphire laser.

  9. Room-temperature laser annealing for solid-phase epitaxial crystallization of β-Ga2O3 thin films

    NASA Astrophysics Data System (ADS)

    Shiojiri, Daishi; Fukuda, Daiji; Yamauchi, Ryosuke; Tsuchimine, Nobuo; Koyama, Koji; Kaneko, Satoru; Matsuda, Akifumi; Yoshimoto, Mamoru

    2016-10-01

    The epitaxial crystallization of β-Ga2O3 thin films on NiO-buffered α-Al2O3(0001) substrates via the solid-phase crystallization of amorphous Ga2O3 thin films by KrF excimer laser annealing at room temperature (RT) was examined. The results of X-ray and reflection high-energy electron diffraction measurements indicated that the epitaxial β-Ga2O3 (\\bar{2}01) thin films were fabricated by RT laser annealing. The optical bandgap of the thin films was estimated to be 4.9 eV from the results of UV/vis transmittance measurements. In the cathodoluminescence spectrum, UV-green luminescence was observed for the thin films. These optical properties are similar to those of bulk β-Ga2O3.

  10. Crystal field disorder effects in the optical spectra of Nd{sup 3+} and Yb{sup 3+}-doped calcium lithium niobium gallium garnets laser crystals and ceramics

    SciTech Connect

    Lupei, V.; Lupei, A.; Gheorghe, C.; Gheorghe, L.; Achim, A.; Ikesue, A.

    2012-09-15

    The optical spectroscopic properties of RE{sup 3+} (Nd, 1 at. % or Yb, 1 to 10 at. %)-doped calcium-lithium-niobium-gallium garnet (CLNGG) single crystals and ceramics in the 10 K-300 K range are analyzed. In these compositionally disordered materials, RE{sup 3+} substitute Ca{sup 2+} in dodecahedral sites and the charge compensation is accomplished by adjusting the proportion of Li{sup +}, Nb{sup 5+}, and Ga{sup 3+} to the doping concentration. The crystals and ceramics show similar optical spectra, with broad and structured (especially at low temperatures) bands whose shape depends on temperature and doping concentration. At 10 K, the Nd{sup 3+4}I{sub 9/2}{yields}{sup 4}F{sub 3/2,5/2} and Yb{sup 3+2}F{sub 7/2}{yields}{sup 2}F{sub 5/2} absorption bands, which show prospect for diode laser pumping, can be decomposed in several lines that can be attributed to centers with large differences in the crystal field. The positions of these components are the same, but the relative intensity depends on the doping concentration and two main centers dominate the spectra. Non-selective excitation evidences broad emission bands, of prospect for short-pulse laser emission, whereas the selective excitation reveals the particular emission spectra of the various centers. The modeling reveals that the nonequivalent centers correspond to RE{sup 3+} ions with different cationic combinations in the nearest octahedral and tetrahedral coordination spheres, and the most abundant two centers have 4Nb and, respectively, 3Nb1Li in the nearest octahedral sphere. At 300 K, the spectral resolution is lost. It is then inferred that the observed optical bands are envelopes of the spectra of various structural centers, whose resolution is determined by the relative contribution of the temperature-dependent homogeneous broadening and the effects of crystal field disordering (multicenter structure, inhomogeneous broadening). The relevance of spectroscopic properties for selection of pumping

  11. Plate-shaped Yb:LuPO4 crystal for efficient CW and passively Q-switched microchip lasers

    NASA Astrophysics Data System (ADS)

    Liu, Junhai; Wang, Lisha; Han, Wenjuan; Xu, Honghao; Zhong, Degao; Teng, Bing

    2016-10-01

    It is demonstrated that plate-shaped crystals of Yb:LuPO4, which are grown from spontaneous nucleation by high-temperature solution method, can be utilized to make microchip lasers operating in continuous-wave (CW) or passively Q-switched mode. Efficient operation of such a microchip laser, which is built with a 0.3 mm thick crystal plate in a 2 mm long plane-parallel cavity, is realized at room temperature. With 2.37 W of pump power absorbed, 1.45 W of CW output power is generated with a slope efficiency of 73%. When passively Q-switched with a Cr4+:YAG crystal plate as saturable absorber, the laser produces a maximum pulsed output power of 0.53 W at 1013.3 nm, at a pulse repetition rate of 23.8 kHz, the resulting pulse energy, duration, and peak power are 22.3 μJ, 4.0 ns, and 5.6 kW, respectively.

  12. Pulsed and continuous-wave laser operation of TGT-grown Nd,Y-codoped :SrF2 single crystal

    NASA Astrophysics Data System (ADS)

    Jelínek, Michal; Kubeček, Václav; Su, Liangbi; Jiang, Dapeng; Ma, Fengkai; Zhang, Qian; Cao, Yuexin; Xu, Jun

    2014-05-01

    In this letter we present laser properties of temperature gradient technique (TGT) grown Nd,Y : SrF2 crystals with Nd3+ concentrations of 0.4, 0.65 and 0.8 at% and Y3+ concentration of 10 at%. The noncoated crystal samples, 3.1 or 5 mm long, were pumped by the 796 nm laser diode matching the Nd,Y : SrF2 absorption peak. In the pulsed pumping regime (pulse-duration 2 ms, frequency 10 Hz), maximum average output power of 75 mW (corresponding to peak power of 3.75 W) was obtained with slope efficiency as high as 51% and optical-to-optical efficiency of 42% with respect to the absorbed pump power. The output beam spatial profile was nearly Gaussian in both axes, oscillations started at the wavelength of 1057 nm. At higher pumping levels, the second emission line at 1051 nm appears corresponding to our fluorescence measurements. Wavelength tuning using a birefringent filter from 1048 to 1070 nm is probably given by the crystal-field splitting of the 4F3/2 manifold in Nd3+. True-continuous-wave laser operation was also successfully obtained at lower pumping levels with maximum output power of 380 mW and slope efficiency of 28% at the wavelength of 1057 nm.

  13. Interaction of intense femtosecond laser pulses with KDP and DKDP crystals in the short wavelength regime.

    PubMed

    Duchateau, Guillaume; Geoffroy, Ghita; Belsky, Andrei; Fedorov, Nikita; Martin, Patrick; Guizard, Stéphane

    2013-10-30

    We investigate the electronic photo-excitation and relaxation mechanisms involved in the optical breakdown of potassium dihydrogen phosphate crystal (KH2PO4) and its deuterated form. The dynamics and spectroscopic properties of electron-hole pair formation are investigated using time-resolved measurement of the dielectric function, and luminescence spectroscopy. The non-common mechanical and electronic characteristics of these dielectric materials are revealed by the particular structure of ablation craters and also by the complex dynamics observed in the relaxation of excited carriers. This relaxation occurs in two steps, and varies with the initial carrier density and thus with the laser intensity. We show that the defect states play a key role in the excitation pathways, and also determine the relaxation stage. The latter also depends upon the initial amount of energy of the electron-hole pair after photo-excitation. A model based on kinetic equations describing the evolution of the different level populations allows us to successfully interpret and reproduce the experimental data. PMID:24100170

  14. Low-damage surface smoothing of laser crystallized polycrystalline silicon using gas cluster ion beam

    NASA Astrophysics Data System (ADS)

    Tokioka, H.; Yamarin, H.; Fujino, T.; Inoue, M.; Seki, T.; Matsuo, J.

    2007-04-01

    Surface smoothing of laser crystallized polycrystalline silicon (poly-Si) films using gas cluster ion beam (GCIB) technology has been studied. It is found that both SF6-GCIB and O2-GCIB decrease the height of hillocks and reduce the surface roughness of the irradiated films. The mean surface roughness value of poly-Si films was reduced from 10.8 nm to 2.8 nm by SF6-GCIB irradiation at 80°. Ultraviolet reflectance measurement reveals that GCIB irradiation causes damage near-surface of the poly-Si films. Formation of the damage, however, can be suppressed by using GCIB irradiation at high incident angle. Effect of GCIB irradiation in a metal-insulator-semiconductor (MIS) capacitor has also been investigated. The capacitance-voltage curves of MIS capacitor with SF6-GCIB irradiation are distorted. On the contrary, the distortion is reduced by O2-GCIB irradiation at 80, which suggests that electrical-activated damage of the films can be decreased by using O2-GCIB irradiation.

  15. Multi-wavelength laser tuning based on cholesteric liquid crystals with nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Sheng-Chieh; Lin, Jia-De; Lee, Chia-Rong; Hwang, Shug-June

    2016-04-01

    A controllable multi-wavelength laser from a dye-doped cholesteric liquid crystal (DDCLC) cell is demonstrated by incorporating self-assembled polyhedral oligomeric silsesquioxane (POSS) nanoparticles (NPs). Multi-wavelength lasing emission is achieved by formation of multiple planar domains; this formation is dominantly influenced by the vertical alignment of NP clusters adsorbed on the substrate surface through a rapid thermal annealing process. The multi-wavelength lasing peaks are generated through the resultant effect of multiple longitudinal resonant modes of a Fabry-Pérot etalon between the cell substrates and the amplification of fluorescence photons with the resonant wavelengths within the broadening long-wavelength edge of the reflection band of the multi-domain CLC. The amount of multi-wavelength lasing peaks can be controlled by changing the POSS NP concentration and the cooling rate of the cell. Furthermore, thermo-reversible control of the multi-wavelength lasing emission can be attained by controlling the thermally induced phase separation process of the POSS/DDCLC cell via a heating/cooling cyclic process.

  16. Strongly driven quantum pendulum of the carbonyl sulfide molecule

    NASA Astrophysics Data System (ADS)

    Trippel, Sebastian; Mullins, Terry; Müller, Nele L. M.; Kienitz, Jens S.; Omiste, Juan J.; Stapelfeldt, Henrik; González-Férez, Rosario; Küpper, Jochen

    2014-05-01

    We demonstrate and analyze a strongly driven quantum pendulum in the angular motion of state-selected and laser-aligned carbonyl sulfide molecules. Raman couplings during the rising edge of a 50-ps laser pulse create a wave packet of pendular states, which propagates in the confining potential formed by the polarizability interaction between the molecule and the laser field. This wave-packet dynamics manifests itself as pronounced oscillations in the degree of alignment with a laser-intensity-dependent period.

  17. Structural studies of bean pod mottle virus, capsid, and RNA in crystal and solution states by laser Raman spectroscopy

    SciTech Connect

    Li, Tiansheng; Thomas, G.J. Jr. ); Chen, Zhongguo; Johnson, J.E. )

    1990-05-29

    Structures of protein and RNA components of bean pod mottle virus (BPMV) have been investigated by use of laser Raman spectroscopy. Raman spectra were collected from both aqueous solutions and single crystals of BPMV capsids (top component) and virions (middle and bottom components, which package, respectively, small and large RNA molecules). Analysis of the data permits the assignment of conformation-sensitive Raman bands to viral protein and RNA constituents and observation of structural similarities and differences between solution and crystalline states of BPMV components. The Raman results show that the protein subunits of the empty capsid contain between 45% and 55% {beta}-strand and {beta}-turn secondary structure, in agreement with the recently determined X-ray crystal structure, and that this total {beta}-strand content undergoes a small increase with packaging of RNA. A comparison of Raman spectra of crystal and solution states of the BPMV middle component reveals only minor structural differences between the two, and these are restricted almost exclusively to Raman bands of RNA in the region of assigned phosphodiester conformation markers. Although in both the crystal and solution only C3{prime} endo/anti nucleosides are detected, the crystal exhibits a weaker 813-cm{sup {minus}1} band and strong 870-cm{sup {minus}1} band, which suggests that {approximately}8% of the nucleotides have O-P-O torsions configured differently in the crystal from that in the solution.

  18. Polarization switching detection method using a ferroelectric liquid crystal for dichroic atomic vapor laser lock frequency stabilization techniques.

    PubMed

    Dudzik, Grzegorz; Rzepka, Janusz; Abramski, Krzysztof M

    2015-04-01

    We present a concept of the polarization switching detection method implemented for frequency-stabilized lasers, called the polarization switching dichroic atomic vapor laser lock (PSDAVLL) technique. It is a combination of the well-known dichroic atomic vapor laser lock method for laser frequency stabilization with a synchronous detection system based on the surface-stabilized ferroelectric liquid crystal (SSFLC).The SSFLC is a polarization switch and quarter wave-plate component. This technique provides a 9.6 dB better dynamic range ratio (DNR) than the well-known two-photodiode detection configuration known as the balanced polarimeter. This paper describes the proposed method used practically in the VCSEL laser frequency stabilization system. The applied PSDAVLL method has allowed us to obtain a frequency stability of 2.7×10⁻⁹ and a reproducibility of 1.2×10⁻⁸, with a DNR of detected signals of around 81 dB. It has been shown that PSDAVLL might be successfully used as a method for spectra-stable laser sources.

  19. In Situ Laser Crystallization of Amorphous Silicon for TFT Applications: Controlled Ultrafast Studies in the Dynamic TEM

    SciTech Connect

    Taheri, M; Teslich, N; Lu, J P; Morgan, D; Browning, N

    2008-02-08

    An in situ method for studying the role of laser energy on the microstructural evolution of polycrystalline Si is presented. By monitoring both laser energy and microstructural evolution simultaneously in the dynamic transmission electron microscope, information on grain size and defect concentration can be correlated directly with processing conditions. This proof of principle study provides fundamental scientific information on the crystallization process that has technological importance for the development of thin film transistors. In conclusion, we successfully developed a method for studying UV laser processing of Si films in situ on nanosecond time scales, with ultimate implications for TFT application improvements. In addition to grain size distribution as a function of laser energy density, we found that grain size scaled with laser energy in general. We showed that nanosecond time resolution allowed us to see the nucleation and growth front during processing, which will help further the understanding of microstructural evolution of poly-Si films for electronic applications. Future studies, coupled with high resolution TEM, will be performed to study grain boundary migration, intergranular defects, and grain size distribution with respect to laser energy and adsorption depth.

  20. Laser performance of in-band pumped Er : LiYF4 and Er : LiLuF4 crystals

    NASA Astrophysics Data System (ADS)

    Gorbachenya, K. N.; Kurilchik, S. V.; Kisel, V. E.; Yasukevich, A. S.; Kuleshov, N. V.; Nizamutdinov, A. S.; Korableva, S. L.; Semashko, V. V.

    2016-02-01

    Spectroscopic properties of Er : LiLuF4 and Er : LiYF4 crystals in the spectral region near 1.5 μm and the lasing characteristics of these crystals under in-band pumping at a wavelength of 1522 nm are studied. With the Er : LiLuF4 crystal, the maximum slope efficiency with respect to the absorbed pump power was 44% at a wavelength of 1609 nm. Continuous-wave operation of an inband pumped Er : LiYF4 laser is obtained for the first time. The output power at a wavelength of 1606 nm was 58 mW with a slope efficiency of 21%.

  1. Crystal growth, frequency doubling, and infrared laser performance of Yb{sup 3+}:BaCaBO{sub 3}F

    SciTech Connect

    Schaffers, K.I.; DeLoach, L.D.; Payne, S.A.

    1996-05-01

    Yb:BaCaBO{sub 3}F (Yb:BCBF) has been investigated as a new laser crystal with potential for self-frequency doubling. Yb{sup 3+} in BCBF exhibits a minimum absorption cross section at 912 nm of 1.1 {times} 10{sup {minus}20} cm{sup 2} with a bandwidth (FWHM) of 19 nm. The maximum emission cross section at 1034 nm is 1.3 {times} 10{sup {minus}20} cm{sup 2} with a transition bandwidth of 24 nm. The measured emission lifetime of Yb{sup 3+} is 1.17 ms. An Yb:BCBF laser has been demonstrated with a Ti:sapphire pump source, and a measured slope efficiency of 38% has been obtained for the fundamental laser output. Single crystal powders of BCBF have been compared with KD*P for a relative measure of the second-harmonic generating potential, yielding d{sub eff} (BCBF) {approximately}0.26 pm/V. The phasematching angle has been estimated from the refractive index data for type 1 second-harmonic generation of 0.517 {micro}m light; the predicted angle is 37{degree} from the c-axis. The growth, spectroscopy, laser performance, and linear and nonlinear optical properties of Yb:BCBF are reported.

  2. Frequency doubling of 1560nm diode laser via PPLN and PPKTP crystals and frequency stabilization to rubidium absorption line

    NASA Astrophysics Data System (ADS)

    Guo, Shanlong; Yang, Jianfeng; Yang, Baodong; Zhang, Tiancai; Wang, Junmin

    2010-11-01

    In our experiment, a polarization-maintaining (PM) fiber-pigtailed butterfly-sealed 1560nm distributed-feedback (DFB) laser diode is amplified by a 5-Watt EDFA, then a multiple-period PPLN crystal (1mm×10mm×20mm) and a single-period PPKTP crystal (1mm×2mm×30mm) are utilized to perform SHG via single pass configuration. The second harmonic power of ~ 239 mW@780 nm for PPLN and ~ 210 mW@780 nm for PPKTP are obtained with ~5W@1560 nm laser input, corresponding to SHG efficiency of ~ 5.2% for PPLN and ~ 4.4% for PPKTP, respectively. Finally the 1560 nm laser diode's frequency is locked to rubidium absorption line via SHG and rubidium absorption spectroscopy, the laser frequency drift for free-running case is ~ 56 MHz in 30 s, the residual frequency after being locked drift is ~ +/- 3.5 MHz.

  3. Laser characteristics of low-threshold high-efficiency Nd:Sr5(VO4)3F crystal

    NASA Astrophysics Data System (ADS)

    Wang, Qingpu; Zhao, Shengzhi; Zhang, Xingyu

    1995-06-01

    The absorption spectrum of a new crystal, Nd: Sr 5( VO4) 3F (Nd:S-VAP), was measured, which showed that Nd:S-VAP can be suitably pumped at 583.0 and 809.0 nm as well as with a xenon flash lamp. With a tunable dye laser (570-600 nm) and a xenon flash lamp as pump sources, respectively, the free-running and Q -switched outputs with BDN dye film were realized at 1.065 mu m . For the tunable dye-laser pump source the threshold energy is 2 mJ and the slope efficiency is 50%, while for the xenon flash-lamp pump source the lowest threshold energy is 130 mJ and the highest slope efficiency is 1.3%. The laser characteristics, such as the emission spectrum, the polarization, the output energy, and the pulse width, were measured. In addition, the prospect of a Nd:S-VAP crystal for low-threshold, high-efficiency miniature lasers is discussed.

  4. Efficient frequency doubler of 1560 nm laser based on a semi-monolithic resonant cavity with a PPKTP crystal

    NASA Astrophysics Data System (ADS)

    Wang, Junmin; Zhang, Kong; Ge, Yulong; Guo, Shanlong

    2016-06-01

    We have demonstrated 1.61 W of 780 nm single-frequency continuous-wave laser output with a semi-monolithic periodically poled potassium titanyl phosphate (PPKTP) crystal doubler pumped by a 2-W erbium-doped fiber amplifier boosted 1560 nm diode laser. The measured maximum doubling efficiency is 77%, and the practical value should be 80% when taking into account the fundamental-wave mode matching efficiency. The measured beam quality factor of 780 nm output, M2, is better than 1.04. Typical root-mean-square fluctuation of 780 nm output is less than 0.5% in 30 minutes. This compact frequency doubler has good mechanical stability, and can be employed for many applications, such as laser cooling and trapping, atomic coherent control, atomic interferometer, and quantum frequency standard with rubidium atoms.

  5. Intracavity SRS conversion in diode-pumpedmultifunctional Nd{sup 3+}:SrMoO{sub 4} laser crystal

    SciTech Connect

    Basiev, Tasoltan T; Smetanin, Sergei N; Fedin, Aleksandr V; Shurygin, Anton S

    2010-10-15

    Lasing of a miniature all-solid-state SRS laser based on a Nd{sup 3+}:SrMoO{sub 4} crystal with a LiF:F{sub 2}{sup -}-passive Q-switch is studied. The dependences of the laser and SRS self-conversion parameters on the initial transmission of the passive Q-switch are studied experimentally and theoretically. Simulation of the lasing kinetics has shown the possibility of nonlinear cavity dumping upon highly efficient SRS self-conversion of laser radiation. An increase in the active medium length from 1 to 3mm resulted in an increase in the energy of the output 1.17-{mu}m SRS radiation from 20 {mu}J to record-high 60 {mu}J at the absorbed multimode diode pump energy of 3.7 mJ. (nonlinear optical phenomena)

  6. Spectral and lasing characteristics of dye-doped cholesteric liquid crystals as materials for laser projection screens

    NASA Astrophysics Data System (ADS)

    Ilchishin, Igor P.

    2004-07-01

    Absorbtion spectra, fluorescence spectra and quantum yields of dyes of various classes in cholesteric liquid crystals (CLC) and in isotropic solutions as well as the thresholds oftheir lasing in CLC were investigated. The increase ofquantum yields of dyes in concentrated CLC-solution in comparison with diluted isotropic ones are established for the first time. It has been shown that neutral phenolenone dyes with voluminose terminal groups which hinder aggregation of their molecules in concentrated solutions. The experimental investigations of the lasing efficiency of a distributed feedback laser (DFB) based on CLC from excitation intensity and optical density of dye in the active layer are presented. The thermal phase grating induced by laser radiation in doped CLC, as it is shown, the high << effective Q>> of the CLC layers are compensated and the lasing efficiency ofthis lasers are improved.

  7. Design and fabrication of hollow-core photonic crystal fibers for high power fast laser beam transportation and pulse compression

    NASA Astrophysics Data System (ADS)

    Wang, Y. Y.; Peng, Xiang; Alharbi, M.; Dutin, C. F.; Bradley, T. D.; Mielke, Michael; Booth, Timothy; Benabid, F.

    2012-03-01

    We report on recent design and fabrication of Kagome type hollow-core photonic crystal fiber (HC-PCF) for the purpose of high power fast laser beam transportation. The fabricated seven-cell three-ring hypocycloid-shaped large core fiber exhibits an up-to-date lowest attenuation (among all Kagome fibers) of 40dB/km over a broadband transmission centered at 1500nm. We show that the large core size, low attenuation, broadband transmission, single modedness, low dispersion and relatively low banding loss makes it an ideal host for high power laser beam transportation. By filling the fiber with helium gas, a 74μJ, 850fs and 40kHz repetition rate ultra-short pulse at 1550nm has been faithfully delivered with little propagation pulse distortion. Compression of a 105μJ laser pulse from 850fs to 300fs has been achieved by operating the fiber in ambient air.

  8. CW and passively Q-switched laser performance of Nd:Lu2SiO5 crystal

    NASA Astrophysics Data System (ADS)

    Xu, Xiaodong; Di, Juqing; Zhang, Jian; Tang, Dingyuan; Xu, Jun

    2016-01-01

    We demonstrated an efficient and controllable dual-wavelength continuous-wave (CW) laser of Nd:Lu2SiO5 (Nd:LSO) crystal. The maximum output power was 3.02 W at wavelength of 1075 nm and 1079 nm, and with increasing of absorbed pump power, the ratio of 1079 nm laser rose. The slope efficiency of 65.6% and optical-to-optical conversion efficiency of 63.3% were obtained. The passively Q-switched laser properties of Nd:LSO were investigated for the first time. The shortest pulse, maximum pulse energy and peak power were 11.58 ns, 29.05 μJ and 2.34 kW, respectively.

  9. A CW green laser emission by self-sum-frequency-mixing in Nd:GdCOB crystal

    NASA Astrophysics Data System (ADS)

    Shao, Y.; Jin, H. J.; Lin, J.; Zhang, D.; Tao, Z. H.; Zhang, T. Y.; Li, Y. L.; Ruan, Q. R.

    2011-10-01

    A compact and efficient green laser light at 538 nm produced by self-sum-frequency-mixing of both fundamental infrared laser waves (1061 and 1091 nm) in Nd:GdCa4O(BO3)3 (Nd:GdCOB) crystal is demonstrated. With 18.2 W of diode pump power, a maximum output power of 1.73 W in the green spectral range at 538 nm has been achieved, corresponding to an optical-to-optical conversion efficiency of 9.5%; the output power stability over 30 min is better than 3%. To the best of our knowledge, this is first work on self-sum-frequency-mixing of a diode pumped Nd:GdCOB laser.

  10. Morphology and orientation of β-BaB{sub 2}O{sub 4} crystals patterned by laser in the inside of samarium barium borate glass

    SciTech Connect

    Nishii, Akihito; Shinozaki, Kenji; Honma, Tsuyoshi; Komatsu, Takayuki

    2015-01-15

    Nonlinear optical β-BaB{sub 2}O{sub 4} crystal lines (β-BBO) were patterned in the inside of 8Sm{sub 2}O{sub 3}–42BaO–50B{sub 2}O{sub 3} glass by irradiations of continuous-wave Yb:YVO{sub 4} lasers with a wavelength of 1080 nm (power: P=0.8–1.0 W, scanning speed: S=0.2–2.5 μm/s), in which the laser focal position was moved gradually from the surface to the inside. The morphology, size, and orientation of β-BBO crystals were examined from polarization optical microscope and birefringence imaging observations. It was demonstrated that c-axis oriented β-BBO crystals with long lengths (e.g., 20 mm) were patterned in the inside of the glass. The morphology of β-BBO in the cross-section of lines was a rectangular shape with rounded corners, and the volume of β-BBO formed increased with increasing laser power and with decreasing laser scanning speed. The maximum depth in the inside from the surface for β-BBO patterning increased with increasing laser power, e.g., D{sub max}∼100 μm at P=0.8 W, D{sub max}∼170 μm at P=0.9 W, and D{sub max}∼200 μm at P=1 W. The present study proposes that the laser-induced crystallization opens a new door for applied engineering in glassy solids. - Graphical abstract: This figure shows the POM photographs for β-BaB{sub 2}O{sub 4} crystal lines patterned by cw Yb:YVO{sub 4} fiber laser irradiations with a laser power of P=0.8 W and a laser scanning speed S=2 μm/s in the glass. The laser focal point was moved gradually from the surface into the inside. The results shown in Fig. 1 demonstrate that it is possible to pattern highly oriented β-BaB{sub 2}O{sub 4} crystals even in the inside of glasses. - Highlights: • β-BaB{sub 2}O{sub 4} crystal lines were patterned in the inside of a glass by lasers. • Laser focal position was moved gradually from the surface to the inside. • Birefringence imaging was observed. • Morphology, size, and orientation of crystals were clarified. • Crystal lines with long lengths

  11. Computational study of the generation of crystal defects in a bcc metal target irradiated by short laser pulses

    NASA Astrophysics Data System (ADS)

    Lin, Zhibin; Johnson, Robert A.; Zhigilei, Leonid V.

    2008-06-01

    The generation of crystal defects in a Cr target irradiated by a short, 200 fs, laser pulse is investigated in computer simulations performed with a computational model that combines the classical molecular dynamics method with a continuum description of the laser excitation of conduction band electrons, electron-phonon coupling, and electron heat conduction. Interatomic interactions are described by the embedded atom method (EAM) potential with a parametrization designed for Cr. The potential is tested by comparing the properties of the EAM Cr material with experimental data and predictions of density functional theory calculations. The simulations are performed at laser fluences close to the threshold for surface melting. Fast temperature variation and strong thermoelastic stresses produced by the laser pulse are causing surface melting and epitaxial resolidification, transient appearance of a high density of stacking faults along the {110} planes, and generation of a large number of point defects (vacancies and self-interstitials). The stacking faults appear as a result of internal shifts in the crystal undergoing a rapid uniaxial expansion in the direction normal to the irradiated surface. The stacking faults are unstable and disappear shortly after the laser-induced tensile stress wave leaves the surface region of the target. Thermally activated generation of vacancy-interstitial pairs during the initial temperature spike and quick escape of highly mobile self-interstitials to the melting front or the free surface of the target, along with the formation of vacancies at the solid-liquid interface during the fast resolidification process, result in a high density of vacancies, on the order of 10-3 per lattice site, created in the surface region of the target. The strong supersaturation of vacancies can be related to the incubation effect in multipulse laser ablation/damage and should play an important role in mixing/alloying of multicomponent or composite

  12. Investigations on structural, optical, dielectric, laser damage threshold and NLO properties of 2-amino-5-nitropyridinium p-tolunesulfonate (2A5NPT) single crystal

    NASA Astrophysics Data System (ADS)

    Pandian, Muthu Senthil; Sivasubramani, V.; Ramasamy, P.

    2016-05-01

    The highly efficient organic nonlinear optical (NLO) 2-amino-5-nitropyridinium p-tolunesulfonate single crystals have been grown by conventional slow evaporation technique using Millipore water as a solvent in the period of 60 days. The single crystal XRD confirms the unit cell parameters of the grown crystal. The morphology of the grown crystal was analyzed using Bruker-Kappa APEXII single crystal instrument and their planes are identified. The optical transmittance range and the cut-off wavelength are recorded using UV-Visible NIR characterization. The laser damage threshold (LDT) studies were carried out using Nd:YAG laser and LDT value was found to be 3.7 GW/cm2. The dielectric constant and dielectric loss of 2A5NPT single crystals were measured. The SHG efficiency was tested by powder Kurtz-Perry technique and the SHG efficiency is 15 times greater than that of standard KDP material.

  13. Sulfide Mineralogy and Geochemistry

    NASA Astrophysics Data System (ADS)

    Dilles, John

    2007-02-01

    Reviews in Mineralogy and Geochemistry Series, Volume 61 David J. Vaughan, Editor Geochemical Society and Mineralogical Society of America; ISBN 0-939950-73-1 xiii + 714 pp.; 2006; $40. Sulfide minerals as a class represent important minor rock-forming minerals, but they are generally known as the chief sources of many economic metallic ores. In the past two decades, sulfide research has been extended to include important roles in environmental geology of sulfide weathering and resultant acid mine drainage, as well as in geomicrobiology in which bacteria make use of sulfides for metabolic energy sources. In the latter respect, sulfides played an important role in early evolution of life on Earth and in geochemical cycling of elements in the Earth's crust and hydrosphere.

  14. Liquid crystal near-IR laser beam shapers employing photoaddressable alignment layers for high-peak-power applications

    NASA Astrophysics Data System (ADS)

    Marshall, Kenneth L.; Saulnier, Debra; Xianyu, Haiqing; Serak, Svetlana; Tabiryan, Nelson

    2013-09-01

    Large-scale, high-energy Nd:glass laser systems require beam shapers to control the spatial distribution of the incident intensity. Commercially available liquid crystal (LC) electro-optical spatial light modulators (SLM's) are frequently employed for this purpose, but their intrinsic requirement for conductive metal or metal-oxide coatings limits their 1054-nm laser-damage thresholds to 230 mJ/cm2 (2.4 ns, 5 Hz), relegating them for use only in low-fluence areas of the laser system. Previously, we demonstrated that passive near-IR LC beam shapers employing coumarin alignment layers patterned by contact photolithography are capable of high resolution and contrast and can withstand incident 1054-nm laser-fluence levels of <30 J/cm2 (1-ns pulse). An evolutionary step to expand the scope of this simple and robust device would be to identify and incorporate into the device structure photoalignment layers that trigger LC bulk reorientation by undergoing reversible optical switching between two predetermined alignment patterns using low-energy polarized UV/visible incident light and have a high near-IR laser-damage threshold. Such "optically driven" LC beam shapers offer the in-system write/erase flexibility of the electro-optical LC SLM's while eliminating conductive coatings that compromise the laser-damage threshold and electrical interconnects that increase device fragility and complexity. To this end, we have recently identified and evaluated the 1054-nm laser-damage-resistance and coating properties of several commercial azobenzene-based photoswitchable alignment materials. In 1-on-1 and N-on-1 testing, these new materials displayed 1054-nm laser-damage thresholds that compare very favorably to those of previously tested coumarin photoalignment materials (30 to 60 J/cm2).

  15. Laser damage threshold and nonlinear optical studies on guanidinium L - monohydrogen tartrate (GuHT) single crystal for NLO device applications

    NASA Astrophysics Data System (ADS)

    Vivek, P.; Murugakoothan, P.

    2015-06-01

    An organic NLO material guanidinium l - monohydrogen tartrate (GuHT) was grown by the slow evaporation technique using water as a solvent. The GuHT crystal belongs to orthorhombic system with noncentrosymmetric space group P212121. The morphology of the GuHT crystal was studied. The laser induced surface damage threshold behaviour of the GuHT crystal was analyzed in different planes. The second harmonic generation (SHG) effective nonlinearity was confirmed by Kurtz and Perry powder technique.

  16. Nonlinear optical crystal development for laser wavelength shifting at AFRL Materials Directorate

    NASA Astrophysics Data System (ADS)

    Fernelius, Nils C.; Hopkins, Frank K.; Ohmer, M. C.

    1999-06-01

    Our objective is to develop crystals that shift the light from well developed laser sources to application specific wavelengths which may be tunable. Military applications extend across the entire spectrum from ultraviolet through the far-infrared but our greatest interest has been in materials for the mid-IR (3-5 μm) and far-IR (8-12 μm) atmospheric windows. Our primary applications that drive crystal development are infrared countermeasures and remote sensing of chemical and biological warfare agents. To achieve these results we have pursued two tracks: birefringent bulk materials and quasi-phase-matched structures. Birefringent studies include the grey track problem in KTiOPO4 (KTP) plus growth of its isomorphs, KTIOAsO4 (KTA), RbTiOAsO4 (RTA), CsTiOAsO4 (CTA), and KxRb1-xTiOPO4 (KRTA); chalcopyrites: ZnGeP2, CdGeAs2, AgGaS2, AgGaSe2, AgGa(1-x)InxSe2, AgGaTe2; plus GaSE, and HgGa2S4. A small portion of the effort is pursuing UV materials, the foremost being the borates MM'(B3O5)3 where M=Sr, Ba, Pb; M'=Li,Na. Previously, work was done on LiB3O5 (LBO), β-bonding (GaAs), by periodic poling (LiNbO3, LiTaO3, KTP, BaTiO3) and by periodic doping. Th cover the 4.5-5.0 μm band, work is being done on RTA and Pb{MgxNbyTi1-x-y}O3 (PMNT). For periodic poling in the 8-12 μm region studies are being made on CGC (CsGeCl3), CGB (CsGeBr3), Tl3PbBr5, Tl4PbI6 and Tl4HgI6. QPM can also be obtained using total internal reflection devices (GaAs, ZnSe).

  17. Silicate melt removal and sulfide liquid retention in ultramafic rocks of the Duke Island Complex, Southeastern Alaska

    NASA Astrophysics Data System (ADS)

    Stifter, Eric C.; Ripley, Edward M.; Li, Chusi

    2014-10-01

    Magmatic Ni-Cu-PGE sulfide mineralization occurs within olivine clinopyroxenite, hornblende-bearing clinopyroxenite, and magnetite-hornblende-rich rocks in the Ural-Alaskan-Type Duke Island Complex in Southeast Alaska. The addition of large amounts of sulfur from country rocks occurred during fractional crystallization of the parental magma when clinopyroxene was becoming a liquidus mineral. Textural interfaces between sulfide and silicate minerals are strongly interlobate, and differ significantly from net-textures that are developed in many Ni-Cu-PGE deposits. Sulfide-free olivine clinopyroxenite is an adcumulate; residual liquid was efficiently expelled from the accumulating crystal pile. A significant interstitial liquid component is observable only in the form of interstitial sulfide in the S-rich rocks. Rounded sulfide inclusions and blebby to vermicular sulfide-silicate intergrowths indicate that silicate crystallization occurred under conditions of sulfide saturation. The presence of dense sulfide liquid inhibited the growth of silicate minerals and led to the development of interlobate grain boundaries. Strong, localized wetting of sulfide liquids on crystallizing silicates, and downward percolation of sulfide liquid through a crystallizing mush may have contributed to the evolution of these textures. Residual silicate liquid was removed from the system due to a combination of buoyant advection and compaction, but dense sulfide liquid remained.

  18. Difference-frequency generation in the field of a few-cycle laser pulse propagating in a GaAs crystal with a domain structure

    SciTech Connect

    Oganesyan, David L; Vardanyan, Aleksandr O; Oganesyan, G D

    2013-06-30

    Difference-frequency generation in a GaAs crystal with a periodic domain structure in the field of a few-cycle laser pulse is considered for the case of weakly pronounced material dispersion. The straight-line method is used to solve numerically the system of coupled nonlinear partial differential equations describing the evolution of the electric field of this laser pulse in GaAs crystals with periodic and chirped domain structures. It is shown that application of a GaAs crystal with a chirped domain structure makes it possible to control the frequency-modulation law for a broadband differencefrequency pulse. (nonlinear optical phenomena)

  19. Report on the Study of Radiation Damage in Calcium Fluoride and Magnesium Fluoride Crystals for use in Excimer Laser Applications

    SciTech Connect

    None, None

    1999-10-04

    A study was performed to investigate the effects of radiation damage in calcium fluoride and magnesium fluoride crystals caused by gamma rays and UV photons from excimer lasers. The purpose was to study and correlate the damage caused by these two different mechanisms in various types of material used for fabricating optical elements in high power excimer lasers and lens systems of lithography tools. These optical systems are easily damaged by the laser itself, and it is necessary to use only the most radiation resistant materials for certain key elements. It was found that a clear correlation exists between the, radiation induced damage caused by high energy gamma rays and that produced by UV photons from the excimer laser. This correlation allows a simple procedure to be developed to select the most radiation resistant material at the ingot level, which would be later used to fabricate various components of the optical system. This avoids incurring the additional cost of fabricating actual optical elements with material that would later be damaged under prolonged use. The result of this screening procedure can result in a considerable savings in the overall cost of the lens and laser system.

  20. Quantitative study of stress levels in AT and BT cut quartz crystal microbalances associated with surface laser irradiation

    NASA Astrophysics Data System (ADS)

    Goodman, L. H.; Bililign, E. S.; McCann, B. J.; Keller, B. W.; Stevens, K.; Kenny, S. G.; Krim, J.

    The frequency response of an AT cut Quartz Crystal Microbalance (QCM) to laser irradiation has been increasingly studied in recent years, as the combination of photons with materials on a QCM's electrodes enables fundamental studies of topics that span biophysics to photovoltaics. In order for such studies to advance, however, the impact of heating effects associated with laser irradiation of the QCM must be accounted for. Prior studies reached qualitative conclusions that laser irradiation induces stress QCM's arising from non-uniform thermal expansion, but did not quantitatively measure the degree of stress. Secondary effects such as surface film desorption and/or changes in temperature were also reported to be present. We report here a study of the frequency response of AT and BT cut QCM's to laser irradiation. AT and BT cut QCM's have similar response to mass adsorption, but opposite frequency response to stress levels, allowing the stress levels induced by the laser light to be quantitatively measured when the results are compared. Studies were performed in both vacuum and air, to control for the presence of adsorbed films. As expected, system designs that minimize temperature gradients result in less of an effect. Work supported by NSF DMR-1310456.

  1. Adaptive correction of vortex laser beam in a closed-loop system with phase only liquid crystal spatial light modulator

    NASA Astrophysics Data System (ADS)

    Ma, Haotong; Liu, Zejin; Wu, Huiyun; Xu, Xiaojun; Chen, Jinbao

    2012-03-01

    We propose and demonstrate the wave front correction of a vortex laser beam by using dual phase only liquid crystal spatial light modulators (LC-SLMs) and a stochastic parallel gradient descent (SPGD) algorithm. One phase only LC-SLM is used to generate vortex laser beam by loading spiral phase screen onto the wave front of input quasi-Gaussian beam. The other phase only LC-SLM under SPGD controller based on the subzone control method adaptively compensates the wave front of vortex laser beam. Numerical simulation and experimental results show that after correction, vortex doughnut like beam is focused into a beam with airy disk pattern distribution in the far field. The adaptive corrections of vortex laser beam with different optical topological charges are studied. The results show that the optical topological charge has little influence on adaptive correction. The powers in the main lobe of far field intensity distributions of vortex laser beams with different optical topological charges are all greatly improved by adaptive correction. The technique proposed in this paper can be used in optical communication, relay mirror and atmospheric turbulence correction.

  2. Material properties of pulsed-laser crystallized Si thin films grown on yttria-stabilized zirconia crystallization-induction layers by two-step irradiation method

    NASA Astrophysics Data System (ADS)

    Thi Kieu Lien, Mai; Horita, Susumu

    2016-03-01

    Amorphous Si thin films on yttria-stabilized zirconia (YSZ) layers were crystallized widely in solid phase by the two-step method with a pulsed laser, moving the sample stage. The crystalline quality, impurity diffusion, and electrical properties of the crystallized Si films were investigated. It was found that the crystallinity of the Si thin films was improved and their surface was smooth without an incubation layer at the interface, indicating the uniform crystallinity of Si on YSZ. The diffusion of Zr and Y into the Si thin films was as small as or smaller than the order of 1017 atoms/cm3. We evaluated the electrical properties of carrier concentration and Hall mobility of the Si thin films with/without YSZ layers by using the resistivity and AC Hall effect measurements. The temperature and doping concentration dependences were measured for both undoped and P-doped films. It was found that both the undoped and P-doped Si/YSZ/glass films showed higher mobilities and carrier concentrations (and therefore higher conductivities), which indicate a smaller number of defects, than the Si/glass films. This suggested that the Si film crystallized on the YSZ layer is more suitable for application to electronic devices than the Si film on glass.

  3. Femtosecond laser-induced crystallization of amorphous N-doped Ge{sub 8}Sb{sub 92} films and in situ characterization by coherent phonon spectroscopy

    SciTech Connect

    Li, Zhongyu; Wen, Ting; Lai, Tianshu E-mail: jwzhai@tongji.edu.cn; Hu, Yifeng; Zhai, Jiwei E-mail: jwzhai@tongji.edu.cn

    2015-04-07

    Femtosecond laser-irradiation-induced phase change of amorphous N-doped Ge{sub 8}Sb{sub 92} films is in situ studied by coherent phonon spectroscopy. We have observed that a new coherent optical phonon (COP) mode occurs as laser irradiation fluence reaches certain thresholds, indicating laser-induced phase changes. Additionally, this new phonon mode has also been verified in heat-annealing-crystallized N-doped Ge{sub 8}Sb{sub 92} films, confirming the emergence of laser-irradiation-induced crystallization. By measuring the pump fluence dependence of COP dynamics in laser-crystallized N-doped Ge{sub 8}Sb{sub 92} films, we found that the frequency and lifetime of COP decrease with the increasing of pump fluence, which suggests good crystallinity in laser-crystallized N-doped Ge{sub 8}Sb{sub 92} films. It has also been observed that the crystallization temperature of amorphous N-doped Ge{sub 8}Sb{sub 92} films increases with N-doping content. Our results indicate promising applications of N-doped Ge{sub 8}Sb{sub 92} films in optical phase-change memory devices.

  4. Femtosecond laser-induced crystallization of amorphous N-doped Ge8Sb92 films and in situ characterization by coherent phonon spectroscopy

    NASA Astrophysics Data System (ADS)

    Li, Zhongyu; Hu, Yifeng; Wen, Ting; Zhai, Jiwei; Lai, Tianshu

    2015-04-01

    Femtosecond laser-irradiation-induced phase change of amorphous N-doped Ge8Sb92 films is in situ studied by coherent phonon spectroscopy. We have observed that a new coherent optical phonon (COP) mode occurs as laser irradiation fluence reaches certain thresholds, indicating laser-induced phase changes. Additionally, this new phonon mode has also been verified in heat-annealing-crystallized N-doped Ge8Sb92 films, confirming the emergence of laser-irradiation-induced crystallization. By measuring the pump fluence dependence of COP dynamics in laser-crystallized N-doped Ge8Sb92 films, we found that the frequency and lifetime of COP decrease with the increasing of pump fluence, which suggests good crystallinity in laser-crystallized N-doped Ge8Sb92 films. It has also been observed that the crystallization temperature of amorphous N-doped Ge8Sb92 films increases with N-doping content. Our results indicate promising applications of N-doped Ge8Sb92 films in optical phase-change memory devices.

  5. Comparison of actively Q-switched laser performance of disordered Yb:Ca3La2(BO3)4 crystals cut along the crystallographic axes.

    PubMed

    Wang, Yeqing; Chen, Aixi; Tu, Chaoyang

    2015-03-10

    In this paper, actively Q-switched laser operation with an acousto-optic switch has been demonstrated by using Yb:Ca3La2(BO3)4 crystals cut along the a, b, and c crystallographic axes. The most efficient Q-switched laser operation was obtained by using b-cut Yb:Ca3La2(BO3)4 crystal with 1 kHz pulse repetition frequency, generating laser pulses of 0.5 mJ, 42.56 KW peak power and 9 ns pulse width, when the output couplings were 3%, 5%, and 5%, respectively. Pulse performances and output laser spectra of the a-, b-, and c-cut Yb:Ca3La2(BO3)4 crystals were compared under similar experimental conditions. PMID:25968384

  6. Nonequivalent Yb{sup 3+} centres in Y{sub 1-x}Yb{sub x}Al{sub 3}(BO{sub 3}){sub 4} laser crystals

    SciTech Connect

    Boldyrev, K N; Popova, Marina N; Bezmaternykh, L N; Betinelli, M

    2011-02-28

    The absorption spectra of nonlinear laser crystals Y{sub 1-x}Yb{sub x}Al{sub 3}(BO{sub 3}){sub 4} grown from bismuth-lithium-molybdate and potassium-molybdate solution-melts are comparatively studied by high-resolution Fourier spectroscopy. The differences observed in the fine structure of the absorption spectra are correlated with the variations in the solution-melt composition and in the concentrations of bismuth and molybdenum impurities in the crystals. It is shown that the concentration of the molybdenum impurity (the main factor hindering lasing in the UV spectral region) in the single crystals grown from the bismuth-lithium-molybdate solutions is more than an order of magnitude smaller than in the crystals grown using the potassium-molybdate solution-melt. The described method can be used for express analysis of the quality of UV laser crystals and for improving the solution-melt technologies of growth of laser crystals and crystals used for generation of the fourth harmonic of Nd:YAG laser radiation. (active media)

  7. Novel liquid-crystal alignment method using polarized laser light (Invited Paper)

    NASA Astrophysics Data System (ADS)

    Sun, Shao-Tang; Gibbons, Wayne M.; Shannon, Paul J.

    1992-10-01

    The control of liquid crystal alignment is of critical importance to the electro-optic performance of a liquid crystal display. Recently a new alignment method was discovered. Instead of the conventional buffing technique, polarized light is employed to treat the polymer alignment layer on the substrate of the display cell for the control of liquid crystal orientation. This non-contact method of aligning liquid crystals offers unique possibilities for display cell repair or reconfiguration after cell assembly. In addition, novel liquid crystal phase devices can be realized for use in optical processing.

  8. Photonic crystal-based flat lens integrated on a Bragg mirror for high-Q external cavity low noise laser.

    PubMed

    Seghilani, M S; Sellahi, M; Devautour, M; Lalanne, P; Sagnes, I; Beaudoin, G; Myara, M; Lafosse, X; Legratiet, L; Yang, J; Garnache, A

    2014-03-10

    We demonstrate a high reflectivity (> 99%), low-loss (< 0.1%) and aberrations-free (2% of λ rms phase fluctuations) concave Bragg mirror (20mm radius of curvature) integrating a photonic crystal with engineered spherical phase and amplitude transfer functions, based on a III-V semiconductors flat photonics technology. This mirror design is of high interest for highly coherent high power stable external cavity semiconductor lasers, exhibiting very low noise. We design the photonic crystal for operation in the pass band. The approach incorporates spatial, spectral (filter bandwidth= 5nm) and polarization filtering capabilities. Thanks to the mirror, a compact single mode TEM(00) 2mm-long air gap high finesse (cold cavity Q-factor 10(6) - 10(7)) stable laser cavity is demonstrated with a GaAs-based quantum-wells 1/2-VCSEL gain structure at 1μm. Excellent laser performances are obtained in single frequency operation: low threshold density of 2kW/cm(2) with high differential efficiency (21%). And high spatial, temporal and polarization coherence: TEM(00) beam close to diffraction limit, linear light polarization (> 60dB), Side Mode Suppression Ratio > 46dB, relative intensity noise at quantum limit (< -150dB) in 1MHz-84GHz radio frequency range, and a theoretical linewidth fundamental limit at 10 Hz (Q-factor ∼ 3.10(13)). PMID:24663933

  9. An Elliptical Crystal Spectrometer Suitable for EXAFS Studies of Laser Compressed Materials and for High Resolution X-Ray Spectroscopy.

    PubMed

    Ridgeley, A; Goodman, D; Hall, T A

    1995-01-01

    Using an x-ray spectrometer with an elliptically curved crystal it is possible to study absorption spectra from a target placed at one focus of the ellipse using a backlighting source placed at the other focus. This principle has been used to develop a spectrometer for EXAFS studies of laser compressed materials. The backlighting source is placed at one focus of the ellipse and the laser compressed EXAFS sample at the other. Using this technique a small area of the EXAFS target can be probed, thereby minimizing any spatial variations in the compressed plasma due to nonuniformities in the laser beams. Also, the dispersive nature of the crystal ensures that it acts as a bandpass filter, so that the EXAFS sample is not probed by other x-ray wavelengths which may cause unwanted heating. Another advantage is that compressed and uncompressed EXAFS spectra can be compared on a single shot. The optical properties of the spectrometer are discussed analytically and using a computer ray-tracing program. The development and alignment of the elliptical spectrometer are discussed, and its performance using both x-ray film and a CCD detector is evaluated. The use of the elliptical spectrometer as a high-resolution x-ray instrument is presented. PMID:21307480

  10. Photonic crystal-based flat lens integrated on a Bragg mirror for high-Q external cavity low noise laser.

    PubMed

    Seghilani, M S; Sellahi, M; Devautour, M; Lalanne, P; Sagnes, I; Beaudoin, G; Myara, M; Lafosse, X; Legratiet, L; Yang, J; Garnache, A

    2014-03-10

    We demonstrate a high reflectivity (> 99%), low-loss (< 0.1%) and aberrations-free (2% of λ rms phase fluctuations) concave Bragg mirror (20mm radius of curvature) integrating a photonic crystal with engineered spherical phase and amplitude transfer functions, based on a III-V semiconductors flat photonics technology. This mirror design is of high interest for highly coherent high power stable external cavity semiconductor lasers, exhibiting very low noise. We design the photonic crystal for operation in the pass band. The approach incorporates spatial, spectral (filter bandwidth= 5nm) and polarization filtering capabilities. Thanks to the mirror, a compact single mode TEM(00) 2mm-long air gap high finesse (cold cavity Q-factor 10(6) - 10(7)) stable laser cavity is demonstrated with a GaAs-based quantum-wells 1/2-VCSEL gain structure at 1μm. Excellent laser performances are obtained in single frequency operation: low threshold density of 2kW/cm(2) with high differential efficiency (21%). And high spatial, temporal and polarization coherence: TEM(00) beam close to diffraction limit, linear light polarization (> 60dB), Side Mode Suppression Ratio > 46dB, relative intensity noise at quantum limit (< -150dB) in 1MHz-84GHz radio frequency range, and a theoretical linewidth fundamental limit at 10 Hz (Q-factor ∼ 3.10(13)).

  11. GV /m Single-Cycle Terahertz Fields from a Laser-Driven Large-Size Partitioned Organic Crystal

    NASA Astrophysics Data System (ADS)

    Vicario, Carlo; Monoszlai, Balazs; Hauri, Christoph P.

    2014-05-01

    We report on compact and efficient laser-based THz generation in the terahertz frequency gap (1-10 THz). The radiation is generated by optical rectification of a midinfrared laser in a large-size, partitioned nonlinear organic crystal assembly. This enables up-scaling of presently field-limited tabletop THz sources to GV /m electric and several tesla magnetic field at millijoule pulse energy. In agreement with simulations, the THz beam properties at focus are shown to be not deteriorated by the discontinuity of the emitter surface. The high laser-to-THz energy conversion efficiency exceeds the Manley-Rowe limit and is explained by a cascaded χ(2) process in the organic crystals accompanied by a significant redshift of the pump spectrum. The scheme provides a compact, tabletop THz source for single-cycle transients at field strength equivalent or even higher to linear accelerator and FEL-based THz sources. This opens an avenue toward novel nonlinear THz applications.

  12. A study on crystalline perfection, optical, dielectric, mechanical, laser damage threshold and NLO properties of glycine added potassium dihydrogen phosphate single crystals

    SciTech Connect

    Boopathi, K.; Rajesh, P.; Ramasamy, P.

    2012-06-05

    Single crystals of glycine doped potassium dihydrogen phosphate have been grown by slow evaporation solution technique, slow cooling along with seed rotation and Sankaranaryanan-Ramasamy method. The size of the grown crystal in slow cooling method was 35x25x20 mm{sup 3} and in SR method it was 20 mm in diameter and 110 mm in length. The grown crystals were characterized by HRXRD, UV-Visible, dielectric, Vickers microhardness, laser damage threshold and SHG studies. The crystalline perfection of the grown crystals has been analyzed by high resolution X-ray diffraction. The transmittance of the grown crystals is 66%, 70%, and 77% respectively and all the crystals have good transparency in the entire visible region. The crystal grown by SR method glycine added KDP has much higher hardness value than other method grown crystals. Higher laser damage threshold was observed in SR method grown glycine added KDP crystal compared to SR method grown pure KDP crystal. The second harmonic generation efficiency of the glycine doped KDP is increased compared to pure KDP.

  13. Use of Zinc Sulfide as a Self-Focusing Element in a Self-Starting Kerr Lens Modelocked TITANIUM:SAPPHIRE Laser

    NASA Astrophysics Data System (ADS)

    Pearson, Gary Whiton

    Scope and method of study. A numerical model of Kerr Lens Modelocking (KLM) in a Ti:sapphire laser with an additional highly nonlinear self-focusing element was developed using the Hankel transform beam propagation method. The influence on nonlinear self-focusing element position and the nonlinear index of refraction, n_2, were tested. The numerical model was used to optimize the design of an experimental linear cavity Ti:sapphire laser with an additional highly nonlinear self-focusing element in the cavity. Various materials were tested with a wide range of nonlinear index of refractions, including: quartz, SF11 glass, cubic zirconia, ZnS, ZnSe, and CdS. Tests for self-modelocking pump power threshold, self-starting, and long term stability were done on the laser with the different nonlinear materials used as self-focusing elements. Findings and conclusions. The numerical portion of the study showed for the first time that Kerr Lens Modelocking does not act like a saturable absorber in that self-focusing does not 'bleach'. Instead, there is a minimum loss intracavity power, beyond which intracavity loss increases with increase in intracavity power. This limits the pulse peak power and may be an explanation for multi-pulsing seen in over pumped KLM lasers. Additionally, a much steeper initial slope in the power vs. loss relation suggested that increasing the n_2 in the KLM laser cavity could make the system self-starting and reduce the need for high power argon ion pump lasers. The experimental portion of the study produced the first known truly self -starting linear cavity KLM Ti:sapphire laser. Further, the self-modelocking pump power threshold was significantly lowered as well and stability considerably enhanced. The best results were obtained with monocrystalline ZnS.

  14. Investigation of continuous wave and pulsed laser performance based on Nd3+:Gd0.6Y1.4SiO5 crystal

    NASA Astrophysics Data System (ADS)

    Feng, Chao; Liu, Zhaojun; Cong, Zhenhua; Shen, Hongbin; Li, Yongfu; Wang, Qingpu; Fang, Jiaxiong; Xu, Xiaodong; Xu, Jun; Zhang, Xingyu

    2015-12-01

    We systematically investigated a laser diode (LD) pumped Nd:GYSO (Nd3+:Gd0.6Y1.4SiO5) laser. The output power of the continuous wave laser was as high as 3.5 W with a slope efficiency of 31.8%. In the Q-switched operation; the laser exhibited dual-wavelengths output (1073.6 nm and 1074.7 nm) synchronously with a Cr4+:YAG as the saturable absorber (SA). Additionally, a passively mode-locked laser was demonstrated using a semiconductor SA mirror with a maximum average output power of 510 mW at a central wavelength of 1074 nm, while the pulse width of the laser was as short as 5 ps. Our experiment proved that the Nd:GYSO mixed crystal was a promising material for a solid-state laser.

  15. Lasing and laser-induced motion of zinc oxide nano-crystals irradiated by ultraviolet laser beam

    NASA Astrophysics Data System (ADS)

    Okazaki, K.; Nakamura, D.; Higashihata, M.; Okada, T.

    2011-03-01

    The lasing characteristics and the alignment methods of ZnO nanocrystals were investigated for an application to ultraviolet (UV) laser diode (LD). ZnO nanowires and nanosheets were synthesized on a silicon substrate by a CVD method or nanoparticle assisted pulsed-laser deposition (NAPLD), and then those ZnO nanocrystals were examined by a photoluminescence (PL) method with a third-harmonic Nd:YAG laser (355 nm, 5 ns). The observed emission spectra showed the obvious lasing characteristics having mode structure and a threshold for lasing. The threshold power density of a ZnO nanowire and a nanosheet were measured to be 100 kW/cm2 and 5 kW/cm2, respectively. Furthermore, the threshold power was calculated to be 8.4 mW for a ZnO nanowire and 2.5 mW for a ZnO nanosheet. Then the oscillation mechanisms were discussed on those ZnO nanocrystals. We also observed the laser-induced motion (LIM) of ZnO nanocrystals when they were excited by ultraviolet laser beam.

  16. Frequency conversion of molecular gas lasers in PbIn6Te10 crystal within mid-IR range.

    PubMed

    Ionin, A A; Kinyaevskiy, I O; Klimachev, Y M; Kotkov, A A; Badikov, V V; Mitin, K V

    2016-05-15

    PbIn6Te10 is a new mid-infrared (IR) nonlinear crystal with a very wide transparency range from 1.7 up to 31 μm. Calculated phase-matching angles show possibility of frequency conversion throughout the transparency range. Sum frequency generation of multiline carbon monoxide (CO) laser and difference frequency generation when mixing CO and carbon dioxide laser radiation were experimentally studied. Laser-induced damage threshold and frequency conversion efficiency under multiline CO laser pumping were measured.

  17. Direct writing of 150 nm gratings and squares on ZnO crystal in water by using 800 nm femtosecond laser.

    PubMed

    Liu, Jukun; Jia, Tianqing; Zhou, Kan; Feng, Donghai; Zhang, Shian; Zhang, Hongxin; Jia, Xin; Sun, Zhenrong; Qiu, Jianrong

    2014-12-29

    We present a controllable fabrication of nanogratings and nanosquares on the surface of ZnO crystal in water based on femtosecond laser-induced periodic surface structures (LIPSS). The formation of nanogrooves depends on both laser fluence and writing speed. A single groove with width less than 40 nm and double grooves with distance of 150 nm have been produced by manipulating 800 nm femtosecond laser fluence. Nanogratings with period of 150 nm, 300 nm and 1000 nm, and nanosquares with dimensions of 150 × 150 nm2 were fabricated by using this direct femtosecond laser writing technique.

  18. Alignment of CH3F in para-H2 crystal studied by IR quantum cascade laser polarization spectroscopy

    NASA Astrophysics Data System (ADS)

    Kawasaki, Hiroyuki; Mizoguchi, Asao; Kanamori, Hideto

    2016-05-01

    In order to investigate the alignment of CH3F in para-H2 crystals, high resolution polarization spectroscopy of the ν3 vibrational band is studied using a quantum cascade laser at 1040 cm-1. It is found that the main and satellite series of peaks in the ν3 vibrational band of CH3F have the same polarization dependence. This result supports the previously proposed cluster model with ortho-H2 in first and second nearest neighbor sites. The observed polarization dependence function is well described by a simple six-axis void model in which CH3F is not aligned along the c-axis of the crystal but tilted to 64.9(3)° from it.

  19. 10-W pulsed operation of substrate emitting photonic-crystal quantum cascade laser with very small divergence.

    PubMed

    Yao, Dan-Yang; Zhang, Jin-Chuan; Cathabard, Olivier; Zhai, Shen-Qiang; Liu, Ying-Hui; Jia, Zhi-Wei; Liu, Feng-Qi; Wang, Zhan-Guo

    2015-01-01

    High-power broad area substrate emitting photonic-crystal distributed feedback (DFB) quantum cascade lasers (QCLs) emitting around 4.73 μm is reported. Two-dimensional centered rectangular photonic-crystal (CRPC) grating is introduced to enhance optical coherence in large area device. Main lobe far-field radiation pattern with a very small divergence angle of about 0.65° × 0.31° is obtained. A record peak output power for vertical emitting QCLs exceeding 10 W is obtained with high reflectivity (HR) coating. Robust single longitudinal mode emission with a side mode suppression ratio (SMSR) of 30 dB is continuously tunable by the heat sink temperature up to 65°C. PMID:25977652

  20. Alignment of CH3F in para-H2 crystal studied by IR quantum cascade laser polarization spectroscopy.

    PubMed

    Kawasaki, Hiroyuki; Mizoguchi, Asao; Kanamori, Hideto

    2016-05-14

    In order to investigate the alignment of CH3F in para-H2 crystals, high resolution polarization spectroscopy of the ν3 vibrational band is studied using a quantum cascade laser at 1040 cm(-1). It is found that the main and satellite series of peaks in the ν3 vibrational band of CH3F have the same polarization dependence. This result supports the previously proposed cluster model with ortho-H2 in first and second nearest neighbor sites. The observed polarization dependence function is well described by a simple six-axis void model in which CH3F is not aligned along the c-axis of the crystal but tilted to 64.9(3)° from it.