Sample records for pumped 3he laser

  1. A compact spin-exchange optical pumping system for 3He polarization based on a solenoid coil, a VBG laser diode, and a cosine theta RF coil (United States)

    Lee, Sungman; Kim, Jongyul; Moon, Myung Kook; Lee, Kye Hong; Lee, Seung Wook; Ino, Takashi; Skoy, Vadim R.; Lee, Manwoo; Kim, Guinyun


    For use as a neutron spin polarizer or analyzer in the neutron beam lines of the HANARO (High-flux Advanced Neutron Application ReactOr) nuclear research reactor, a 3He polarizer was designed based on both a compact solenoid coil and a VBG (volume Bragg grating) diode laser with a narrow spectral linewidth of 25 GHz. The nuclear magnetic resonance (NMR) signal was measured and analyzed using both a built-in cosine radio-frequency (RF) coil and a pick-up coil. Using a neutron transmission measurement, we estimated the polarization ratio of the 3He cell as 18% for an optical pumping time of 8 hours.

  2. Metastability exchange optical pumping in {sup 3}He gas up to 30 mT. Efficiency measurements and evidence of laser-induced nuclear relaxation

    Energy Technology Data Exchange (ETDEWEB)

    Batz, Marion


    Advances in metastability exchange optical pumping (MEOP) of {sup 3}He at high laser powers, with its various applications, but also at high gas pressures p{sub 3} and high magnetic field strengths B, have provided strong motivation for revisiting the understanding and for investigating the limitations of this powerful technique. For this purpose, we present systematic experimental and theoretical studies of efficiency and of relaxation mechanisms in B{<=}30 mT and p{sub 3}=0.63-2.45 mbar. {sup 3}He nuclear polarisation is measured by light absorption in longitudinal configuration where weak light beams at 1083 nm parallel to magnetic field and cell axis with opposite circular polarisations are used to probe the distribution of populations in the metastable state. This method is systematically tested to evaluate potential systematic biases and is shown to be reliable for the study of OP dynamics despite the redistribution of populations by OP light. Nuclear polarisation loss associated to the emission of polarised light by the plasma discharge used for MEOP is found to decrease above 10 mT, as expected, due to hyperfine decoupling in highly excited states. However, this does not lead to improved MEOP efficiency at high laser power. We find clear evidence of additional laser-induced relaxation instead. The strong OP-enhanced polarisation losses, currently limiting MEOP performances, are quantitatively investigated using an angular momentum budget approach and a recently developed comprehensive model that describes the combined effects of OP, ME and relaxation, validated by comparison to experimental results.

  3. Increasing the pump-up rate to polarize 3He gas using spin-exchange optical pumping method (United States)

    Lee, Wai Tung; Tong, Xin; Rich, Dennis; Liu, Yun; Fleenor, Michael; Ismaili, Akbar; Pierce, Joshua; Hagen, Mark; Dadras, Jonny; Robertson, J. Lee


    In recent years, polarized 3He gas has increasingly been used as neutron polarizers and polarization analyzers. Two of the leading methods to polarize the 3He gas are the spin-exchange optical pumping (SEOP) method and the meta-stable exchange optical pumping (MEOP) method. At present, the SEOP setup is comparatively compact due to the fact that it does not require the sophisticated compressor system used in the MEOP method. The temperature and the laser power available determine the speed, at which the SEOP method polarizes the 3He gas. For the quantity of gas typically used in neutron scattering work, this speed is independent of the quantity of the gas required, whereas the polarizing time using the MEOP method is proportional to the quantity of gas required. Currently, using the SEOP method to polarize several bar-liters of 3He to 70% polarization would require 20-40 h. This is an order of magnitude longer than the MEOP method for the same quantity of gas and polarization. It would therefore be advantageous to speed up the SEOP process. In this article, we analyze the requirements for temperature, laser power, and the type of alkali used in order to shorten the time required to polarize 3He gas using the SEOP method.

  4. Liquid crystal polarimetry for metastability exchange optical pumping of {sup 3}He

    Energy Technology Data Exchange (ETDEWEB)

    Maxwell, J.D., E-mail:; Epstein, C.S.; Milner, R.G.


    We detail the design and operation of a compact, discharge light polarimeter for metastability exchange optical pumping of {sup 3}He gas near 1 torr under a low magnetic field. The nuclear polarization of {sup 3}He can be discerned from its electron polarization, measured via the circular polarization of 668 nm discharge light from an RF excitation. This apparatus measures the circular polarization of this very dim discharge light using a nematic liquid crystal wave retarder (LCR) and a high-gain, transimpedance amplified Si photodiode. We outline corrections required in such a measurement and discuss contributions to its systematic error.

  5. Experimental study of fusion neutron and proton yields produced by petawatt-laser-irradiated D2-3He or CD4-3He clustering gases

    CERN Document Server

    Bang, W; Bonasera, A; Quevedo, H J; Dyer, G; Bernstein, A C; Hagel, K; Schmidt, K; Gaul, E; Donovan, M E; Consoli, F; De Angelis, R; Andreoli, P; Barbarino, M; Kimura, S; Mazzocco, M; Natowitz, J B; Ditmire, T


    We report on experiments in which the Texas Petawatt laser irradiated a mixture of deuterium or deuterated methane clusters and helium-3 gas, generating three types of nuclear fusion reactions: D(d, 3He)n, D(d, t)p and 3He(d, p)4He. We measured the yields of fusion neutrons and protons from these reactions and found them to agree with yields based on a simple cylindrical plasma model using known cross sections and measured plasma parameters. Within our measurement errors, the fusion products were isotropically distributed. Plasma temperatures, important for the cross sections, were determined by two independent methods: (1) deuterium ion time-of-flight, and (2) utilizing the ratio of neutron yield to proton yield from D(d, 3He)n and 3He(d, p)4He reactions, respectively. This experiment produced the highest ion temperature ever achieved with laser-irradiated deuterium clusters.

  6. Temperature Measurements of Fusion Plasmas Produced by Laser-Irradiated D2-3 He or CD4-3 He Clustering Gases (United States)

    Bang, W.; Ditmire, T.; Quevedo, H.; Dyer, G.; Bernstein, A. C.; Donovan, M.; Gaul, E.; Barbui, M.; Bonasera, A.; Hagel, K.; Natowitz, J. B.


    We report on experiments in which a mixture of D2 or CD4 clusters and 3He gas was irradiated by a petawatt-laser pulse, generating nuclear fusion reactions such as D(d, 3He) n, D(d, t) p , and 3He(d, p)4He. We measured the yields of fusion neutrons and protons from these reactions and found them to agree with yields based on a simple cylindrical plasma model. The plasma temperature was determined by two different methods. In the first, it was derived from time-of-flight data of deuterium ions ejected from exploding D2 or CD4 clusters. In the second, it was measured from the ratio of neutron yield to proton yield from D(d, 3He) n and 3He(d, p)4He reactions, respectively. The temperatures determined by these two methods agree well, indicating (i) the ion energy distribution is not significantly distorted when ions travel in the disassembling plasma; (ii) the kinetic energy of deuterium ions, especially the hottest part responsible for nuclear fusion, is well described by a near-Maxwellian distribution.

  7. Temperature measurements of fusion plasmas produced by petawatt laser-irradiated D2-3He or CD4-3He clustering gases

    CERN Document Server

    Bang, W; Bonasera, A; Dyer, G; Quevedo, H J; Hagel, K; Schmidt, K; Consoli, F; De Angelis, R; Andreoli, P; Gaul, E; Bernstein, A C; Donovan, M; Barbarino, M; Kimura, S; Mazzocco, M; Sura, J; Natowitz, J B; Ditmire, T


    Two different methods have been employed to determine the plasma temperature in a laser-cluster fusion experiment on the Texas Petawatt laser. In the first, the temperature was derived from time-of-flight data of deuterium ions ejected from exploding D2 or CD4 clusters. In the second, the temperature was measured from the ratio of the rates of two different nuclear fusion reactions occurring in the plasma at the same time: D(d, 3He)n and 3He(d, p)4He. The temperatures determined by these two methods agree well, which indicates that: i) The ion energy distribution is not significantly distorted when ions travel in the disassembling plasma; ii) The kinetic energy of deuterium ions, especially the hottest part responsible for nuclear fusion, is well described by a near-Maxwellian distribution.

  8. A measurement of the absolute neutron beam polarization produced by an optically pumped sup 3 He neutron spin filter

    CERN Document Server

    Rich, D R; Crawford, B E; Delheij, P P J; Espy, M A; Haseyama, T; Jones, G; Keith, C D; Knudson, J; Leuschner, M B; Masaike, A; Masuda, Y; Matsuda, Y; Penttilae, S I; Pomeroy, V R; Smith, D A; Snow, W M; Szymanski, J J; Stephenson, S L; Thompson, A K; Yuan, V


    The capability of performing accurate absolute measurements of neutron beam polarization opens a number of exciting opportunities in fundamental neutron physics and in neutron scattering. At the LANSCE pulsed neutron source we have measured the neutron beam polarization with an absolute accuracy of 0.3% in the neutron energy range from 40 meV to 10 eV using an optically pumped polarized sup 3 He spin filter and a relative transmission measurement technique. sup 3 He was polarized using the Rb spin-exchange method. We describe the measurement technique, present our results, and discuss some of the systematic effects associated with the method.

  9. Numerical simulation for nuclear pumped laser

    Energy Technology Data Exchange (ETDEWEB)

    Sakasai, Kaoru [Japan Atomic Energy Research Inst., Tokyo (Japan)


    To apply nuclear pumped laser of {sup 3}He-Ne-Ar gas to detect neutron, the optimum gas mixture was investigated by numerical simulation. When {sup 3}He-Ne-Ar mixture gas are irradiated by neutron, proton and triton with high velocity are produced by {sup 3}He(np)T and two charge particles ionized {sup 3}He, Ne and Ar which reacted each other and attained to 3p`(1/2){sub 0}-3S`(1/2). The calculation method is constructed by defining the rate equations of each ion and exited atom and the electron energy balance equation and by time integrating the simultaneous differential equations of the above two equations and the law of conservation of charge. Penning ionization and energy transport by elastic collision of neutral atom were considered in the transport process of electron energy direct ionization by secondary charge particle. Calculation time was 1 msec. The optimum component was shown 3 atm He, 24 Torr He and 8 Torr Ar by simulation. Laser oscilation was generated under the conditions 3.3 x 10{sup 14} (N/cm{sup 2}/5) thermal neutron flux at 50 cm laser cell length and 99% coefficient of reflection of mirror. After laser oscilation, laser output was proportional to neutron flux. These results showed nuclear pumped laser of {sup 3}He-Ne-Ar was able to detect optically neutron. (S.Y)

  10. Nuclear-pumped lasers

    CERN Document Server

    Prelas, Mark


    This book focuses on Nuclear-Pumped Laser (NPL) technology and provides the reader with a fundamental understanding of NPLs, a review of research in the field, and exploration of large scale NPL system design and applications. Early chapters look at the fundamental properties of lasers, nuclear-pumping and nuclear reactions that may be used as drivers for nuclear-pumped lasers. The book goes on to explore the efficient transport of energy from the ionizing radiation to the laser medium and then the operational characteristics of existing nuclear-pumped lasers. Models based on Mathematica, explanations and a tutorial all assist the reader’s understanding of this technology. Later chapters consider the integration of the various systems involved in NPLs and the ways in which they can be used, including beyond the military agenda. As readers will discover, there are significant humanitarian applications for high energy/power lasers, such as deflecting asteroids, space propulsion, power transmission and mining....

  11. A high-field 3He Metastability Exchange Optical Pumping polarizer operating in a 1.5 T medical scanner for lung MRI

    CERN Document Server

    Collier, G; Wojna, A; Głowacz, B; Suchanek, M; Olejniczak, Z; Dohnalik, T


    After being hyperpolarized using the technique of Metastability Exchange Optical Pumping (MEOP), 3He can be used as a contrast agent for lung magnetic resonance imaging (MRI). MEOP is usually performed at low magnetic field (~ 1 mT) and low pressure (~ 1 mbar), which results in a low magnetization production rate. A delicate polarization-preserving step of compression is also required. It was demonstrated in sealed cells that high nuclear polarization values can be obtained at higher pressures with MEOP, if performed at high magnetic field (non-standard conditions). In this work the feasibility of building a high-field polarizer that operates within a commercial 1.5 T scanner was evaluated. Preliminary measurements of nuclear polarization with sealed cells filled at different 3He gas pressures (1.33 to 267 mbar) were performed. The use of an annular shape for the laser beam increased by 25 % the achievable nuclear polarization equilibrium value (Meq) at 32 and 67 mbar as compared to a Gaussian beam shape. Meq...

  12. Diode-pumped dye laser (United States)

    Burdukova, O. A.; Gorbunkov, M. V.; Petukhov, V. A.; Semenov, M. A.


    This letter reports diode pumping for dye lasers. We offer a pulsed dye laser with an astigmatism-compensated three-mirror cavity and side pumping by blue laser diodes with 200 ns pulse duration. Eight dyes were tested. Four dyes provided a slope efficiency of more than 10% and the highest slope efficiency (18%) was obtained for laser dye Coumarin 540A in benzyl alcohol.

  13. Lasers with nuclear pumping

    CERN Document Server

    Melnikov, S P; Sizov, A N; Miley, George H


    This book covers the history of lasers with nuclear pumping (Nuclear Pumped Lasers, NPLs). This book showcases the most important results and stages of NPL development in The Russian Federal Nuclear Center (VNIIEF) as well as other Russian and international laboratories, including laboratories in the United States. The basic science and technology behind NPLs along with potential applications are covered throughout the book. As such, this book: ·         Contains a historical overview of the extensive information developed over the past 40 years of work on NPLs ·         Covers the most important results and stages of NPL development, not just in the Russian Federal Nuclear Center, VNIIEF, but also in other laboratories in Russia, the United States , and some other scattered international laboratories ·         Systematizes the fragmented information accumulated over these years of very active research and development As the first comprehensive discussion of NPLs, students, research...

  14. Nuclear pumped gas laser research (United States)

    Thom, K.


    Nuclear pumping of lasers by fission-fragments from nuclear chain reactions is discussed. Application of the newly developed lasers to spacecraft propulsion or onboard power, to lunar bases for industrial processing, and to earth for utilization of power without pollution and hazards is envisioned. Emphasis is placed on the process by which the fission-fragement kinetic energy is converted into laser light.

  15. Pumping of titanium sapphire laser (United States)

    Jelínková, H.; Vaněk, P.; Valach, P.; Hamal, K.; Kubelka, J.; Škoda, V.; Jelínek, M.


    Two methods of Ti:Sapphire pumping for the generation of tunable laser radiation in the visible region were studied. For coherent pumping, the radiation of the second harmonic of a Nd:YAP laser was used and a maximum output energy of E out=4.5 mJ was reached from the Ti:Sapphire laser. For noncoherent pumping, two different lengths of flashlamp pulses were used and a maximum of E out=300 mJ was obtained. Preliminary estimations of the wavelength range of tunability were made.

  16. Development of polarized {sup 3}He filter for polarized neutron experiment

    Energy Technology Data Exchange (ETDEWEB)

    Sakai, K.; Sato, H.; Yoshimi, A.; Asahi, K. [Tokyo Inst. of Tech. (Japan). Faculty of Science; Masuda, Y.; Muto, S.; Ishimoto, S.; Morimoto, K.


    A high-pressure polarized {sup 3}He gas cell, pumped with two diode lasers, has been developed at KEK for use as a polarizer and a spin analyzer for low energy neutrons. The polarization attained of {sup 3}He was determined through the measurement of the transmission of the unpolarized neutrons through the {sup 3}He cell. So far we obtained P{sub He}=18% at 10 atm and P{sub He}=12% at 20 atm. (author)

  17. Diode Pumped Fiber Laser. (United States)


    FIBER LASERS I. Nd:YAG FIBER LASER FABRICATION .............. 5 A. FIBER GROWTH .......................... 5 B. FIBER PROCESSING 7...1.32 pm FIBER LASERS I. Nd:YAG FIBER LASER FABRICATION A. FIBER GROWTH The single crystal fibers used in this work were grown at Stanford University

  18. Transverse pumped laser amplifier architecture (United States)

    Bayramian, Andrew James; Manes, Kenneth; Deri, Robert; Erlandson, Al; Caird, John; Spaeth, Mary


    An optical gain architecture includes a pump source and a pump aperture. The architecture also includes a gain region including a gain element operable to amplify light at a laser wavelength. The gain region is characterized by a first side intersecting an optical path, a second side opposing the first side, a third side adjacent the first and second sides, and a fourth side opposing the third side. The architecture further includes a dichroic section disposed between the pump aperture and the first side of the gain region. The dichroic section is characterized by low reflectance at a pump wavelength and high reflectance at the laser wavelength. The architecture additionally includes a first cladding section proximate to the third side of the gain region and a second cladding section proximate to the fourth side of the gain region.

  19. New laser materials for laser diode pumping (United States)

    Jenssen, H. P.


    The potential advantages of laser diode pumped solid state lasers are many with high overall efficiency being the most important. In order to realize these advantages, the solid state laser material needs to be optimized for diode laser pumping and for the particular application. In the case of the Nd laser, materials with a longer upper level radiative lifetime are desirable. This is because the laser diode is fundamentally a cw source, and to obtain high energy storage, a long integration time is necessary. Fluoride crystals are investigated as host materials for the Nd laser and also for IR laser transitions in other rare earths, such as the 2 micron Ho laser and the 3 micron Er laser. The approach is to investigate both known crystals, such as BaY2F8, as well as new crystals such as NaYF8. Emphasis is on the growth and spectroscopy of BaY2F8. These two efforts are parallel efforts. The growth effort is aimed at establishing conditions for obtaining large, high quality boules for laser samples. This requires numerous experimental growth runs; however, from these runs, samples suitable for spectroscopy become available.

  20. Electron beam pumped semiconductor laser (United States)

    Hug, William F. (Inventor); Reid, Ray D. (Inventor)


    Electron-beam-pumped semiconductor ultra-violet optical sources (ESUVOSs) are disclosed that use ballistic electron pumped wide bandgap semiconductor materials. The sources may produce incoherent radiation and take the form of electron-beam-pumped light emitting triodes (ELETs). The sources may produce coherent radiation and take the form of electron-beam-pumped laser triodes (ELTs). The ELTs may take the form of electron-beam-pumped vertical cavity surface emitting lasers (EVCSEL) or edge emitting electron-beam-pumped lasers (EEELs). The semiconductor medium may take the form of an aluminum gallium nitride alloy that has a mole fraction of aluminum selected to give a desired emission wavelength, diamond, or diamond-like carbon (DLC). The sources may be produced from discrete components that are assembled after their individual formation or they may be produced using batch MEMS-type or semiconductor-type processing techniques to build them up in a whole or partial monolithic manner, or combination thereof.

  1. Compact and highly efficient laser pump cavity

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Jim J. (Dublin, CA); Bass, Isaac L. (Castro Valley, CA); Zapata, Luis E. (Livermore, CA)


    A new, compact, side-pumped laser pump cavity design which uses non-conventional optics for injection of laser-diode light into a laser pump chamber includes a plurality of elongated light concentration channels. In one embodiment, the light concentration channels are compound parabolic concentrators (CPC) which have very small exit apertures so that light will not escape from the pumping chamber and will be multiply reflected through the laser rod. This new design effectively traps the pump radiation inside the pump chamber that encloses the laser rod. It enables more uniform laser pumping and highly effective recycle of pump radiation, leading to significantly improved laser performance. This new design also effectively widens the acceptable radiation wavelength of the diodes, resulting in a more reliable laser performance with lower cost.

  2. Materials for diode pumped solid state lasers (United States)

    Chase, L. L.; Davis, L. E.; Krupke, W. F.; Payne, S. A.


    The advantages of semiconductor diode lasers and laser arrays as pump sources for solid state lasers are reviewed. The properties that are desirable in solid state laser media for various diode pumping applications are discussed, and the characteristics of several promising media are summarized.

  3. 28W average power hydrocarbon-free rubidium diode pumped alkali laser. (United States)

    Zweiback, Jason; Krupke, William F


    We present experimental results for a high-power diode pumped hydrocarbon-free rubidium laser with a scalable architecture. The laser consists of a liquid cooled, copper waveguide which serves to both guide the pump light and to provide a thermally conductive surface near the gain volume to remove heat. A laser diode stack, with a linewidth narrowed to approximately 0.35 nm with volume bragg gratings, is used to pump the cell. We have achieved 24W average power output using 4 atmospheres of naturally occurring helium ((4)He) as the buffer gas and 28W using 2.8 atmospheres of (3)He.

  4. Diode-pumped laser altimeter (United States)

    Welford, D.; Isyanova, Y.


    TEM(sub 00)-mode output energies up to 22.5 mJ with 23 percent slope efficiencies were generated at 1.064 microns in a diode-laser pumped Nd:YAG laser using a transverse-pumping geometry. 1.32-micron performance was equally impressive at 10.2 mJ output energy with 15 percent slope efficiency. The same pumping geometry was successfully carried forward to several complex Q-switched laser resonator designs with no noticeable degradation of beam quality. Output beam profiles were consistently shown to have greater than 90 percent correlation with the ideal TEM(sub 00)-order Gaussian profile. A comparison study on pulse-reflection-mode (PRM), pulse-transmission-mode (PTM), and passive Q-switching techniques was undertaken. The PRM Q-switched laser generated 8.3 mJ pulses with durations as short as 10 ns. The PTM Q-switch laser generated 5 mJ pulses with durations as short as 5 ns. The passively Q-switched laser generated 5 mJ pulses with durations as short as 2.4 ns. Frequency doubling of both 1.064 microns and 1.32 microns with conversion efficiencies of 56 percent in lithium triborate and 10 percent in rubidium titanyl arsenate, respectively, was shown. Sum-frequency generation of the 1.064 microns and 1.32 microns radiations was demonstrated in KTP to generate 1.1 mJ of 0.589 micron output with 11.5 percent conversion efficiency.

  5. Polarized (3) He Spin Filters for Slow Neutron Physics. (United States)

    Gentile, T R; Chen, W C; Jones, G L; Babcock, E; Walker, T G


    Polarized (3)He spin filters are needed for a variety of experiments with slow neutrons. Their demonstrated utility for highly accurate determination of neutron polarization are critical to the next generation of betadecay correlation coefficient measurements. In addition, they are broadband devices that can polarize large area and high divergence neutron beams with little gamma-ray background, and allow for an additional spin-flip for systematic tests. These attributes are relevant to all neutron sources, but are particularly well-matched to time of flight analysis at spallation sources. There are several issues in the practical use of (3)He spin filters for slow neutron physics. Besides the essential goal of maximizing the (3)He polarization, we also seek to decrease the constraints on cell lifetimes and magnetic field homogeneity. In addition, cells with highly uniform gas thickness are required to produce the spatially uniform neutron polarization needed for beta-decay correlation coefficient experiments. We are currently employing spin-exchange (SE) and metastability-exchange (ME) optical pumping to polarize (3)He, but will focus on SE. We will discuss the recent demonstration of 75 % (3)He polarization, temperature-dependent relaxation mechanism of unknown origin, cell development, spectrally narrowed lasers, and hybrid spin-exchange optical pumping.

  6. Diode-pumped laser with improved pumping system (United States)

    Chang, Jim J.


    A laser wherein pump radiation from laser diodes is delivered to a pump chamber and into the lasing medium by quasi-three-dimensional compound parabolic concentrator light channels. The light channels have reflective side walls with a curved surface and reflective end walls with a curved surface. A flow tube between the lasing medium and the light channel has a roughened surface.

  7. Lasers from fission. [nuclear pumping feasibility experiments (United States)

    Schneider, R. T.; Thom, K.; Helmick, H. H.


    The feasibility of the nuclear pumping of lasers was demonstrated in three experiments conducted independently at three different laboratories. In this context nuclear pumping of lasers is understood to be the excitation of a laser by the kinetic energy of the fission fragments only. A description is given of research concerned with the use of nuclear energy for the excitation of gas lasers. Experimental work was supplemented by theoretical research. Attention is given to a nuclear pumped He-Xe laser, a nuclear pumped CO laser, and a neon-nitrogen laser pumped by alpha particles. Studies involving uranium hexafluoride admixture to laser media are discussed along with research on uranium hexafluoride-fueled reactors.

  8. Pulsed pumping of semiconductor disk lasers. (United States)

    Hempler, Nils; Hopkins, John-Mark; Kemp, Alan J; Schulz, Nico; Rattunde, Marcel; Wagner, Joachim; Dawson, Martin D; Burns, David


    Efficient operation of semiconductor disk lasers is demonstrated using uncooled and inexpensive 905nm high-power pulsed semiconductor pump lasers. Laser emission, with a peak power of 1.7W, is obtained from a 2.3mum semiconductor disk laser. This is seven times the power achieved under continuous pumping. Analysis of the time-dependent spectral characteristics of the laser demonstrate that significant device heating occurs over the 100-200ns duration of the pumping pulse - finite element modelling of the thermal processes is undertaken in support of these data. Spectral narrowing to below 0.8nm is obtained by using an intra-cavity birefringent filter.

  9. Polarization chaos in an optically pumped laser. (United States)

    Serrat, C; Kul'minskii, A; Vilaseca, R; Corbalán, R


    We study the steady-state and dynamic behavior of an optically pumped J = 0 ? J = 1 ? J = 0 laser operating with an isotropic ring cavity and an axial magnetic field. The gain anisotropy induced by a linearly polarized pump-laser f ield leads, in the steady state, to locking of the two circularly polarized components of the laser field, which acquires a linear polarization parallel to that of the pump field. In the presence of laser intensity instabilities, however, locking does not occur, and polarization instabilities appear. For the f irst time to our knowledge, polarization chaos has been found in a laser system.

  10. Cladding For Transversely-Pumped Laser Rod (United States)

    Byer, Robert L.; Fan, Tso Yee


    Combination of suitable dimensioning and cladding of neodymium:yttrium aluminum garnet of similar solid-state laser provides for more efficient utilization of transversely-incident pump light from diode lasers. New design overcomes some of limitations of longitudinal- and older transverse-pumping concepts and promotes operation at higher output powers in TEM00 mode.

  11. Coherent optical pumping of semiconductor lasers

    Energy Technology Data Exchange (ETDEWEB)

    Pfister, M.; Dupertuis, M.A. [Inst. de Micro- et Optoelectronique, Lausanne (Switzerland). Dept. de Physique


    The influence of coherent optical pumping in semiconductor lasers is investigated theoretically. In particular the mathematical conditions under which an optically pumped system behaves like an electrically (incoherently) pumped system are derived. The authors show that it is practically impossible to reach the interesting regime where coherent effects are important because of the inherent constraints to absorb photons at the pump frequency and to reach threshold gain at the lasing frequency. The effects of changing the temperature and of reduced dimensionality are discussed.

  12. Tapered diode laser pumped 946 nm Nd:YAG laser

    DEFF Research Database (Denmark)

    Cheng, Haynes Pak Hay; Jensen, Ole Bjarlin; Petersen, Paul Michael


    We successfully implemented a 946 nm Nd:YAG laser based on a 808 nm tapered diode pump laser. The tapered diode is developed at the Ferdinand-Braun-Institute fur Hochstfrequenztechnik in Germany. Figure 2 shows the experimental setup and results of each pump source coupled into a 1.5 mm crystal...... laser, we show that tapered diode laser pumping potentially increase the power of 946 nm lasers by a factor of two and reduce the threshold by a factor of three....

  13. Laser-induced quantum pumping in graphene

    Energy Technology Data Exchange (ETDEWEB)

    San-Jose, Pablo [Instituto de Estructura de la Materia (IEM-CSIC), Serrano 123, 28006 Madrid (Spain); Prada, Elsa; Kohler, Sigmund [Instituto de Ciencia de Materiales de Madrid, CSIC, Cantoblanco, 28049 Madrid (Spain); Schomerus, Henning [Department of Physics, Lancaster University, Lancaster LA1 4YB (United Kingdom)


    We investigate non-adiabatic electron pumping in graphene generated by laser irradiation with linear polarization parallel or perpendicular to the transport direction. Transport is dominated by the spatially asymmetric excitation of electrons from evanescent into propagating modes. For a laser with parallel polarization, the pumping response exhibits a subharmonic resonant enhancement which directly probes the Fermi energy; no such enhancement occurs for perpendicular polarization. The resonance mechanism relies on the chirality of charge carriers in graphene.

  14. Ho:YLF pumped HBr laser

    CSIR Research Space (South Africa)

    Botha, LR


    Full Text Available . The model included rotational thermalization within a specific vibrational band as well as vibrational relaxation of both the upper and lower vibrational levels partaking in the laser action. The model is similar to that reported in [2] and [7]. The pump.... The efficiency of converting the 2 micron pump energy to 4 micron output energy is primarily controlled by the rotational and vibrational relaxation times. As the pressure of the laser medium is increased, the rotational and vibrational relaxation times...

  15. A high power lamp-pumped LNA laser with thermally tuned etalon (United States)

    Aminoff, C. G.; Essabaa, S.; Brissaud, I.; Arianer, J.


    This report describes arc-lamp pumped, tunable, continuous-wave LNA laser with improved output efficiency, suitable for optical pumping of helium. Using thermal tuning of intracavity etalons instead of angle tuning reduces losses caused by walk-off effects and provides continuous frequency scanning without a significant decrease in laser power. We obtain an output power of 4 W in a linewidth of 2.5 GHz with the laser wavelength tuned to the 1.083 μm absorption line of metastable helium. This result represents a fourfold gain in efficiency compared with conventional tuning by tilting. The laser provides efficient polarization of helium by optical pumping in various applications, such as nuclear spin polarization of 3He and spin-polarized electron sources.

  16. Diode pumped Nd:YAG laser development (United States)

    Reno, C. W.; Herzog, D. G.


    A low power Nd:YAG laser was constructed which employs GaAs injection lasers as a pump source. Power outputs of 125 mW TEM CW with the rod at 250 K and the pump at 180 K were achieved for 45 W input power to the pump source. Operation of the laser, with array and laser at a common heat sink temperature of 250 K, was inhibited by difficulties in constructing long-life GaAs LOC laser arrays. Tests verified pumping with output power of 20 to 30 mW with rod and pump at 250 K. Although life tests with single LOC GaAs diodes were somewhat encouraging (with single diodes operating as long as 9000 hours without degradation), failures of single diodes in arrays continue to occur, and 50 percent power is lost in a few hundred hours at 1 percent duty factor. Because of the large recent advances in the state of the art of CW room temperature AlGaAs diodes, their demonstrated lifetimes of greater than 5,000 hours, and their inherent advantages for this task, it is recommended that these sources be used for further CW YAG injection laser pumping work.

  17. Semiconductor disk laser pumped Cr2+:Znse lasers. (United States)

    Hempler, Nils; Hopkins, John-Mark; Rösener, Benno; Rattunde, Marcel; Wagner, Joachim; Fedorov, Vladimir V; Moskalev, Igor S; Mirov, Sergey B; Burns, David


    A new flexible pump source, the optically-pumped semiconductor disk laser (SDL), for the Cr(2+):ZnSe laser is reported. The SDL provides up to 6W output power at a free running central wavelength of 1.98 microm. The Cr(2+):ZnSe laser operated at an output power of 1.8W and a slope efficiency of approximately 50% with respect to absorbed pump power whilst maintaining a low output intensity noise figure of <0.14% RMS. The system required no optical isolation even under the situation of significant optical feedback.

  18. Solar pumped lasers and their applications (United States)

    Lee, Ja H.

    Since 1980, NASA has been pursuing high power solar lasers as part of the space power beaming program. Materials in liquid, solid, and gas phases have been evaluated against the requirements for solar pumping. Two basic characteristics of solar insolation, namely its diffuse irradiance and 5800 K blackbody-like spectrum, impose rather stringent requirements for laser excitation. However, meeting these requirements is not insurmountable as solar thermal energy technology has progressed today, and taking advantage of solar pumping lasers is becoming increasingly attractive. The high density photons of concentrated solar energy have been used for mainly electric power generation and thermal processing of materials by the DOE Solar Thermal Technologies Program. However, the photons can interact with materials through many other direct kinetic paths, and applications of the concentrated photons could be extended to processes requiring photolysis, photosynthesis, and photoexcitation. The use of solar pumped lasers on Earth seems constrained by economics and sociopolitics. Therefore, prospective applications may be limited to those that require use of quantum effects and coherency of the laser in order to generate extremely high value products and services when conventional and inexpensive means are ineffective or impossible. The new applications already proposed for concentrated solar photons, such as destruction of hazardous waste, production of renewable fuel, production of fertilizer, and air/water pollution controls, may benefit from the use of inexpensive solar pumped laser matched with the photochemical kinetics of these processes.

  19. Development of a 3He nuclear spin flip system on an in-situ SEOP 3He spin filter and demonstration for a neutron reflectometer and magnetic imaging technique (United States)

    Hayashida, H.; Oku, T.; Kira, H.; Sakai, K.; Hiroi, K.; Ino, T.; Shinohara, T.; Imagawa, T.; Ohkawara, M.; Ohoyama, K.; Kakurai, K.; Takeda, M.; Yamazaki, D.; Oikawa, K.; Harada, M.; Miyata, N.; Akutsu, K.; Mizusawa, M.; Parker, J. D.; Matsumoto, Y.; Zhang, S.; Suzuki, J.; Soyama, K.; Aizawa, K.; Arai, M.


    We have been developing a 3He neutron spin filter (NSF) using the spin exchange optical pumping (SEOP) technique. The 3He NSF provides a high-energy polarized neutron beam with large beam size. Moreover the 3He NSF can work as a π-flipper for a polarized neutron beam by flipping the 3He nuclear spin using a nuclear magnetic resonance (NMR) technique. For NMR with the in-situ SEOP technique, the polarization of the laser must be reversed simultaneously because a non-reversed laser reduces the polarization of the spin-flipped 3He. To change the polarity of the laser, a half-wavelength plate was installed. The rotation angle of the half-wavelength plate was optimized, and a polarization of 97% was obtained for the circularly polarized laser. The 3He polarization reached 70% and was stable over one week. A demonstration of the 3He nuclear spin flip system was performed at the polarized neutron reflectometer SHARAKU (BL17) and NOBORU (BL10) at J-PARC. Off-specular measurement from a magnetic Fe/Cr thin film and magnetic imaging of a magnetic steel sheet were performed at BL17 and BL10, respectively.

  20. Scaling studies of solar pumped lasers (United States)

    Christiansen, W. H.; Chang, J.


    A progress report of scaling studies of solar pumped lasers is presented. Conversion of blackbody radiation into laser light has been demonstrated in this study. Parametric studies of the variation of laser mixture composition and laser gas temperature were carried out for CO2 and N2O gases. Theoretical analysis and modeling of the system have been performed. Reasonable agreement between predictions in the parameter variation and the experimental results have been obtained. Almost 200 mW of laser output at 10.6 micron was achieved by placing a small sapphire laser tube inside an oven at 1500 K the tube was filled with CO2 laser gas mixture and cooled by longitudinal nitrogen gas flow.

  1. Heat pump processes induced by laser radiation (United States)

    Garbuny, M.; Henningsen, T.


    A carbon dioxide laser system was constructed for the demonstration of heat pump processes induced by laser radiation. The system consisted of a frequency doubling stage, a gas reaction cell with its vacuum and high purity gas supply system, and provisions to measure the temperature changes by pressure, or alternatively, by density changes. The theoretical considerations for the choice of designs and components are dicussed.

  2. Laser-diode pumped Nd:YAG lasers; Laser diode reiki Nd:YAG lasear

    Energy Technology Data Exchange (ETDEWEB)

    Yuasa, H.; Akiyama, Y.; Nakayama, M. [Toshiba Corp., Tokyo (Japan)


    Laser-diode pumped Nd:YAG lasers are expected to be applied to laser processing fields such as welding, cutting, drilling, and marking due to their potential for high efficiency and compactness. We are designing and developing laser-diode pumped Nd:YAG lasers using numerical analysis simulation techniques such as ray tracing and thermal analysis. We have succeeded in achieving a laser power of more than 3 kW with 20% efficiency, which is the best ever obtained. In addition, we have developed a laser-diode pumped green laser by second harmonic generation, for precision machining on silicon wafers. (author)

  3. Free-running emerald laser pumped by laser diode

    Institute of Scientific and Technical Information of China (English)

    Zhenqiang Chen; Ge Zhang


    Free-running emerald laser pumped by 660-nm laser diode (LD) was reported. Free-running output powerof 24 mW has been obtained with overall efficiency of 1.4% and slope efficiency of 11.9% when the LD incident power was 2.56 W. The laser threshold value of emerald crystal was estimated to be 0.7 W.

  4. Ho:YLF Laser Pumped by TM:Fiber Laser

    Directory of Open Access Journals (Sweden)

    Mizutani Kohei


    Full Text Available A 2-micron Ho:YLF laser end-pumped by 1.94-micron Tm:fiber laser is described. A ring resonator of 3m length is adopted for the oscillator. The laser is a master oscillator and an amplifier system. It is operated at high repetition rate of 200-5000 Hz in room temperature. The laser outputs were about 9W in CW and more than 6W in Q-switched operation. This laser was developed to be used for wind and CO2 measurements.

  5. Modelling end-pumped solid state lasers

    NARCIS (Netherlands)

    Bernhardi, E.H.; Bollig, C.; Forbes, A.; Esser, M.J.D.; Wörhoff, K.; Agazzi, L.; Ismail, N.; Leijtens, X.


    The operation dynamics of end-pumped solid-state lasers are investigated by means of a spatially resolved numerical rate-equation model and a time-dependent analytical thermal model. The rate-equation model allows the optimization of parameters such as the output coupler transmission and gain medium

  6. High power diode lasers for solid-state laser pumps (United States)

    Linden, Kurt J.; McDonnell, Patrick N.


    The development and commercial application of high power diode laser arrays for use as solid-state laser pumps is described. Such solid-state laser pumps are significantly more efficient and reliable than conventional flash-lamps. This paper describes the design and fabrication of diode lasers emitting in the 780 - 900 nm spectral region, and discusses their performance and reliability. Typical measured performance parameters include electrical-to-optical power conversion efficiencies of 50 percent, narrow-band spectral emission of 2 to 3 nm FWHM, pulsed output power levels of 50 watts/bar with reliability values of over 2 billion shots to date (tests to be terminated after 10 billion shots), and reliable operation to pulse lengths of 1 ms. Pulse lengths up to 5 ms have been demonstrated at derated power levels, and CW performance at various power levels has been evaluated in a 'bar-in-groove' laser package. These high-power 1-cm stacked-bar arrays are now being manufactured for OEM use. Individual diode laser bars, ready for package-mounting by OEM customers, are being sold as commodity items. Commercial and medical applications of these laser arrays include solid-state laser pumping for metal-working, cutting, industrial measurement and control, ranging, wind-shear/atmospheric turbulence detection, X-ray generation, materials surface cleaning, microsurgery, ophthalmology, dermatology, and dental procedures.

  7. Diode pumped solid-state laser oscillators for spectroscopic applications (United States)

    Byer, R. L.; Basu, S.; Fan, T. Y.; Kozlovsky, W. J.; Nabors, C. D.; Nilsson, A.; Huber, G.


    The rapid improvement in diode laser pump sources has led to the recent progress in diode laser pumped solid state lasers. To date, electrical efficiencies of greater than 10 percent were demonstrated. As diode laser costs decrease with increased production volume, diode laser and diode laser array pumped solid state lasers will replace the traditional flashlamp pumped Nd:YAG laser sources. The use of laser diode array pumping of slab geometry lasers will allow efficient, high peak and average power solid state laser sources to be developed. Perhaps the greatest impact of diode laser pumped solid state lasers will be in spectroscopic applications of miniature, monolithic devices. Single-stripe diode-pumped operation of a continuous-wave 946 nm Nd:YAG laser with less than 10 m/w threshold was demonstrated. A slope efficiency of 16 percent near threshold was shown with a projected slope efficiency well above a threshold of 34 percent based on results under Rhodamine 6G dye-laser pumping. Nonlinear crystals for second-harmonic generation of this source were evaluated. The KNbO3 and periodically poled LiNbO3 appear to be the most promising.

  8. Solar-pumped gas laser development (United States)

    Wilson, J. W.


    A survey of gas properties through detailed kinetic models led to the identification of critical gas parameters for use in choosing appropriate gas combinations for solar pumped lasers. Broadband photoabsorption in the visible or near UV range is required to excite large volumes of gas and to insure good solar absorption efficiency. The photoexcitation density is independent of the absorption bandwidth. The state excited must be a metastable state which is not quenched by the parent gas. The emission bandwidth must be less than 10 A to insure lasing threshold over reasonable gain lengths. The system should show a high degree of chemical reversibility and an insensitivity to increasing temperature. Other properties such as good quantum efficiency and kinetic efficiency are also implied. Although photoexcitation of electronic vibrational transitions is considered as a possible system if the emission bands sufficiently narrow, it appears that photodissociation into atomic metastables is more likely to result in a successful solar pumped laser system.

  9. New Class of Excimer-Pumped Atomic Lasers (XPALS) (United States)


    appears to be scnlable in power but, more importBntly, the loser gain medium is cooled by the emission orevery laser photon. The smallest energy derect...during high power pumping has been performed. 15.SUBJECT TERMS alkali lasers , optical pumping, laser medium cooling 16. SECURITY CLASSIFICATION OF...critical to the cooling of the laser medium by pumping it through the lower lying states. Results obtained during this program were described in detail

  10. Semiconductor Laser Diode Pumps for Inertial Fusion Energy Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Deri, R J


    Solid-state lasers have been demonstrated as attractive drivers for inertial confinement fusion on the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory (LLNL) and at the Omega Facility at the Laboratory for Laser Energetics (LLE) in Rochester, NY. For power plant applications, these lasers must be pumped by semiconductor diode lasers to achieve the required laser system efficiency, repetition rate, and lifetime. Inertial fusion energy (IFE) power plants will require approximately 40-to-80 GW of peak pump power, and must operate efficiently and with high system availability for decades. These considerations lead to requirements on the efficiency, price, and production capacity of the semiconductor pump sources. This document provides a brief summary of these requirements, and how they can be met by a natural evolution of the current semiconductor laser industry. The detailed technical requirements described in this document flow down from a laser ampl9ifier design described elsewhere. In brief, laser amplifiers comprising multiple Nd:glass gain slabs are face-pumped by two planar diode arrays, each delivering 30 to 40 MW of peak power at 872 nm during a {approx} 200 {micro}s quasi-CW (QCW) pulse with a repetition rate in the range of 10 to 20 Hz. The baseline design of the diode array employs a 2D mosaic of submodules to facilitate manufacturing. As a baseline, they envision that each submodule is an array of vertically stacked, 1 cm wide, edge-emitting diode bars, an industry standard form factor. These stacks are mounted on a common backplane providing cooling and current drive. Stacks are conductively cooled to the backplane, to minimize both diode package cost and the number of fluid interconnects for improved reliability. While the baseline assessment in this document is based on edge-emitting devices, the amplifier design does not preclude future use of surface emitting diodes, which may offer appreciable future cost reductions and

  11. Applications for reactor-pumped lasers (United States)

    Lipinski, R. J.; McArthur, D. A.

    Nuclear reactor-pumped lasers (RPL's) have been developed in the US by the Department of Energy for over two decades, with the primary research occurring at Sandia National Laboratories and Idaho National Engineering Laboratory. The US program has experimentally demonstrated reactor-pumped lasing in various mixtures of xenon, argon, neon, and helium at wavelengths of 585, 703, 725, 1,271, 1,733, 1,792, 2,032, 2,630, 2,650, and 3,370 nm with intrinsic efficiency as high as 2.5%. The major strengths of a reactor-pumped laser are continuous high-power operation, modular construction, self-contained power, compact size, and a variety of wavelengths (from visible to infrared). These characteristics suggest numerous applications not easily accessible to other laser types. The continuous high power of an RPL opens many potential manufacturing applications such as deep-penetration welding and cutting of thick structures, wide-area hardening of metal surfaces by heat treatment or cladding application, wide-area vapor deposition of ceramics onto metal surfaces, production of sub-micron sized particles for manufacturing of ceramics, and 3-D ceramic lithography. In addition, a ground-based RPL could beam its power to space for such activities as illuminating geosynchronous communication satellites in the earth's shadow to extend their lives, beaming power to orbital transfer vehicles, removing space debris, and providing power (from earth) to a lunar base during the long lunar night.

  12. Grating THz laser with optical pumping (United States)

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


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

  13. Cosmic Ray ^3He Measurements


    Mewaldt, R. A.


    Cosmic ray ^3He/^4He observations, including a new measurement at ~65 MeV/nucleon from ISEE-3, are compared with interstellar propagation and solar modulation models in an effort to understand the origin of cosmic ray He nuclei.

  14. Highly-efficient high-power pumps for fiber lasers (United States)

    Gapontsev, V.; Moshegov, N.; Berezin, I.; Komissarov, A.; Trubenko, P.; Miftakhutdinov, D.; Berishev, I.; Chuyanov, V.; Raisky, O.; Ovtchinnikov, A.


    We report on high efficiency multimode pumps that enable ultra-high efficiency high power ECO Fiber Lasers. We discuss chip and packaged pump design and performance. Peak out-of-fiber power efficiency of ECO Fiber Laser pumps was reported to be as high as 68% and was achieved with passive cooling. For applications that do not require Fiber Lasers with ultimate power efficiency, we have developed passively cooled pumps with out-of-fiber power efficiency greater than 50%, maintained at operating current up to 22A. We report on approaches to diode chip and packaged pump design that possess such performance.

  15. Solar-pumped gas laser development (United States)

    Wilson, J. W.


    The direct conversion of solar radiation into an inverted population for extraction in an optical cavity holds promise as a relatively simple system design. Broad-band photoabsorption in the visible or near-UV range is required to excite large volumes of gas and to ensure good solar absorption efficiency. The state excited must be a metastable state which is not quenched by the parent gas. The emission bandwidth must be less than approximately 10 A. The system should show chemical reversibility and an insensitivity to increasing temperature. Other properties such as good quantum efficiency and kinetic efficiency are also implied. A search of electronic-vibrational transitions in diatomic molecules satisfying these conditions is now in progress. A photodissociation-pumped atomic iodine laser is now being tested under solar pumping conditions. Photodissociation studies for thallium spin-flip metastable formation will begin in the near future.

  16. Unidirectionality of an optically pumped far infrared ring laser (United States)

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


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

  17. DOE reactor-pumped laser program

    Energy Technology Data Exchange (ETDEWEB)

    Felty, J.R. [USDOE, Germantown, MD (United States). Defense Programs; Lipinski, R.J.; McArthur, D.A.; Pickard, P.S. [Sandia National Labs., Albuquerque, NM (United States)


    FALCON is a high-power, steady-state, nuclear reactor-pumped laser (RPL) concept that is being developed by the Department of Energy. The FALCON program has experimentally demonstrated reactor-pumped lasing in various mixtures of xenon, argon, neon, and helium at at wavelengths of 585, 703, 725, 1271, 1733, 1792, 2032, 2630, 2650, and 3370 nm with intrinsic efficiency as high as 2.5%. The major strengths of a reactor-pumped laser are continuous high-power operation, modular construction, self-contained power, compact size, and a variety of wavelengths (from visible to infrared). These characteristics suggest numerous applications not easily accessible to other laser types. A ground-based RPL could beam its power to space for such activities as illuminating geosynchronous communication satellites in the earth`s shadow to extend their lives, beaming power to orbital transfer vehicles, removing space debris, and providing power (from earth) to a lunar base during the long lunar night. The compact size and self-contained power also makes an RPL very suitable for ship basing so that power-beaming activities could be situated around the globe. The continuous high power of an RPL opens many potential manufacturing applications such as deep-penetration welding and cutting of thick structures, wide-area hardening of metal surfaces by heat treatment or cladding application, wide-area vapor deposition of ceramics onto metal surfaces, production of sub-micron sized particles for manufacturing of ceramics, wide-area deposition of diamond-like coatings, and 3-D ceramic lithography.

  18. DOE reactor-pumped laser program (United States)

    Felty, James R.; Lipinski, Ronald J.; McArthur, David A.; Pickard, Paul S.


    FALCON is a high-power, steady-state, nuclear reactor-pumped laser (RPL) concept that is being developed by the Department of Energy. The FALCON program has experimentally demonstrated reactor-pumped lasing in various mixtures of xenon, argon, neon, and helium at wavelengths of 585, 703, 725, 1271, 1733, 1792, 2032, 2630, 2650, and 3370 nm with intrinsic efficiency as high as 2.5%. The major strengths of a reactor-pumped laser are continuous high-power operation, modular construction, self-contained power, compact size, and a variety of wavelengths (from visible to infrared). These characteristics suggest numerous applications not easily accessible to other laser types. A ground-based RPL could beam its power to space for such activities as illuminating geosynchronous communication satellites in the earth's shadow to extend their lives, beaming power to orbital transfer vehicles, removing space debris, and providing power (from earth) to a lunar base during the long lunar night. The compact size and self-contained power also makes an RPL very suitable for ship basing so that power-beaming activities could be situated around the globe. The continuous high power of an RPL opens many potential manufacturing applications such as deep-penetration welding and cutting of thick structures, wide-area hardening of metal surfaces by heat treatment or cladding application, wide-area vapor deposition of ceramics onto metal surfaces, production of sub-micron sized particles for manufacturing of ceramics, wide-area deposition of diamond- like coatings, and 3-D ceramic lithography.

  19. Threshold electrodisintegration of 3He (United States)

    Hicks, R. S.; Hotta, A.; Churchwell, S.; Jiang, X.; Peterson, G. A.; Shaw, J.; Asavapibhop, B.; Berisso, M. C.; Bosted, P. E.; Burchesky, K.; Miskimen, R. A.; Rock, S. E.; Nakagawa, I.; Tamae, T.; Suda, T.; Golak, J.; Skibiński, R.; Witała, H.; Casagrande, F.; Turchinetz, W.; Cichocki, A.; Wang, K.; Glöckle, W.; Kamada, H.; Kobayashi, T.; Nogga, A.


    Cross sections were measured for the near-threshold electrodisintegration of 3He at momentum transfer values of q=2.4, 4.4, and 4.7 fm-1. From these and prior measurements the transverse and longitudinal response functions RT and RL were deduced. Comparisons are made against previously published and new nonrelativistic A=3 calculations using the best available nucleon-nucleon NN potentials. In general, for q<2 fm-1 these calculations accurately predict the threshold electrodisintegration of 3He. Agreement at increasing q demands consideration of two-body terms, but discrepancies still appear at the highest momentum transfers probed, perhaps due to the neglect of relativistic dynamics, or to the underestimation of high-momentum wave-function components.

  20. Fiber-laser-pumped Ti:sapphire laser

    CERN Document Server

    Samanta, G K; Devi, Kavita; Ebrahim-Zadeh, M


    We report the first experimental demonstration of efficient and high-power operation of a Ti:sapphire laser pumped by a simple, compact, continuous-wave (cw) fiber-laser-based green source. The pump radiation is obtained by direct single-pass second-harmonic-generation (SHG) of a 33-W, cw Yb-fiber laser in 30-mm-long MgO:sPPLT crystal, providing 11 W of single-frequency green power at 532 nm in TEM00 spatial profile with power and frequency stability better than 3.3% and 32 MHz, respectively, over one hour. The Ti:sapphire laser is continuously tunable across 743-970 nm and can deliver an output power up to 2.7 W with a slope efficiency as high as 32.8% under optimum output coupling of 20%. The laser output has a TEM00 spatial profile with M2<1.44 across the tuning range and exhibits a peak-to-peak power fluctuation below 5.1% over 1 hour.

  1. High level of $^3$He polarization of 81\\% Maintained in an on-beam $^3$He spin filter using SEOP

    CERN Document Server

    Babcock, E; Ioe, A


    Maintaining high levels of 3He polarization over long periods of time is important to many areas of fundamental and particle beam physics. Long measurement times are often required in such experiments and the data quality is a function of the 3He polarization. This is the case for neutron scattering where the 3He can be used to analyze the spin of a scattered neutron beam and relatively small fluxes of polarized neutrons leads to experiment times longer than several days. Consequently the J\\"ulich Centre for Neutron Science (JCNS) is developing spin-exchange optical pumping (SEOP) systems capable of polarizing the 3He gas in place on a typical neutron instrument. Using a polarizer device we constructed a high level of 3He polarization of 81 % \\pm2% was maintained with good time stability. Such levels of polarization maintained over time will be able to reduce the measurement times for such experiments and eliminate time dependent data corrections.

  2. Nuclear pumped laser research at the Jet Propulsion Laboratory (United States)

    Russell, G. R.


    Using a partially nuclear excited xenon flashlamp to pump an iodine laser, laser pulse shapes were analyzed with and without nuclear flashlamp augmentation. The pulse shapes indicate that the deposition of nuclear energy is equally as effective as electrical energy deposition in producing laser pulse energy output. The amplification of the E-beam pumped CF3I was measured at pressures of several atmospheres. Preliminary data shows that, for a part of the iodine laser pulse, amplification of almost a factor of two is measured. This measurement indicates that the gain in an E-beam pumped CF3I is an order of magnitude greater than in the coaxial laser tube.

  3. "Diode Pumped Solid State Lasers At 2 And 3 µm" (United States)

    Esterowitz, Leon


    The most attractive alternative to flashlamp pumping of solid state lasers is the diode laser. In the past two decades numerous laboratory devices have been assembled which incorporated single diode lasers, small laser diode arrays or LED's for pumping of Nd:YAG, Nd:glass and a host of other Nd lasers. The low power output, low packaging density, and extremely high cost of diode lasers prevented any serious applications for laser pumping in the past. The reason for the continued interest in this area stems from the potential dramatic increase in system efficiency and component lifetime, and reduction of thermal load of the solid-state laser material. The latter not only will reduce thereto-optic effects and therefore lead to better beam quality but also will enable an increase in pulse repetition frequency. The attractive operating parameters combined with low voltage operation and the compactness of an all solid-state laser system have a potential high payoff. The high pumping efficiency compared to flashlamps stems from the good spectral match between the laser diode emission and the rare earth activator absorption bands. A significant advantage of laser diode pumping compared to arc lamps is system lifetime and reliability. Laser diode arrays have exhibited lifetimes on the order of 10,000 hours in cw operation and 109 shots in the pulsed mode. Flashlamp life is on the order of 107 shots, and about 200 hours for cw operation. In addition, the high pump flux combined with a substantial UV content in lamp pumped systems causes material degradation in the pump cavity and in the coolant. Such problems are virtually eliminated with laser diode pump sources. The absence of high voltage pulses, high temperatures and UV radiation encountered with arc lamps leads to much more benign operating features for solid state laser systems employing laser diode pumps. Laser diode technology dates back to 1962 when laser action in GaAs diodes was first demonstrated. However, it

  4. High-power optically pumped semiconductor laser apllications (United States)

    Morioka, S. Brandon


    OPS lasers have found applications in various industrial and scientific laser applications due to their power scaling capability, their wide range of emission wavelengths, physical size and their superior reliability. This paper provides an overview of commercially available OPS lasers and the applications in which they are used including biotechnology, medical, holography, Titanium-Sapphire laser pumping, non-lethal defense, forensics, and entertainment.

  5. Threshold ratios for molecular lasers with optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Kuntsevich, B.F.; Churakou, U.V.


    A series of relationships was obtained for threshold characteristics of high pressure molecular lasers with optical pumping. The threshold pumping density increases in proportion to the square of the active medium's pressure. The minimum value of threshold pumping corresponds to the maximum of the Boltzmann distribution function for rotating sublevels both in the pumping channel and in generation. A weak or strong relationship was observed between the threshold impulse energy and the pressure that is caused by fluctuative relaxation of the upper laser level for various relationships between the intensity of the pumping impulse, pressure and loss coefficient.

  6. Vanadium-pumped titanium x-ray laser

    Energy Technology Data Exchange (ETDEWEB)

    Nilsen, J.


    A resonantly photo-pumped x-ray laser is formed of a vanadium and titanium foil combination that is driven by two beams of intense line focused optical laser radiation. Ground state neon-like titanium ions are resonantly photo-pumped by line emission from fluorine-like vanadium ions.

  7. Development of diode-pumped medical solid-state lasers

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Cheol Jung; Kim, Min Suk


    Two thirds of human body consists of water and the absorption of laser by water is an important factor in medical laser treatment. Er medical lasers have been used in the dermatology, ophthalmology and dental treatments due to its highest absorption by water. However, 2.9 um Er laser can not be transmitted through an optical fiber. On the other hand, Tm laser can be transmitted through an fiber and also has very high absorption by water. Therefore, Tm lasers are used in ophthalmology and heart treatment wherein the fiber delivery is very important for the treatment. Until now, mainly lamp-pumped solid-state lasers have been used in medical treatments, but the lamp-pumped solid-state lasers are being replaced with the diode-pumped solid-state lasers because the diode-pumped solid-state lasers are more compact and much easier to maintain. Following this trend, end-pumped Er and side-pumped Tm lasers have been developed and the output power of 1 W was obtained for Er and Tm respectively.

  8. 550-W diode-pumped Nd:YAG disk laser

    Institute of Scientific and Technical Information of China (English)

    Zhenyu Yao; Jianfeng Jiang; Bo Tu; Tangjian Zhou; Lingling Cui


    When a thin laser crystal disk is used with a nearly flat-top pump profile, the heat flux can be considered to be one-dimensional. This results in a homogeneous temperature and stress profile within the laser medium leading to reduction of thermal effects. A nearly flat-top pump profile is achieved with a two-pass cylindrical-lens coupling system. An average output power of 550 W is obtained by an average pumping

  9. Superfluorescent emission in electrically pumped semiconductor laser

    CERN Document Server

    Boiko, D L; Stadelmann, T; Grossmann, S; Hoogerwerf, A; Weig, T; Schwarz, U T; Sulmoni, L; Lamy, J -M; Grandjean, N


    We report superfluorescent (SF) emission in electrically pumped InGaN/InGaN QW lasers with saturable absorber. In particular, we observe a superlinear growth of the peak power of SF pulses with increasing amplitude of injected current pulses and attribute it to cooperative pairing of electron-hole (e-h) radiative recombinations. The phase transitions from amplified spontaneous emission to superfluorescence and then to lasing regime is confirmed by observing (i) superlinear peak power growth, (ii) spectral shape with hyperbolic secant envelope and (iii) red shift of central wavelength of SF emission pulse. The observed red shift of SF emission is shown to be caused by the pairing of e-h pairs in an indirect cooperative X-transition.

  10. Diode-pumped 1123-nm Nd:YAG laser

    Institute of Scientific and Technical Information of China (English)

    Xiaoping Guo(郭晓萍); Meng Chen(陈檬); Gang Li(李港); Bingyuan zhang(张炳元); Jiandong Yang(杨建东); Zhigang Zhang(张志刚); Yonggang Wang(王勇刚)


    We demonstrated a diode-pumped Nd:YAG laser with a plano-concave resonator. When the pump power is 1.57 W, the output power of 1123-nm laser is 132 mW at the temperature of 20 ℃, and the power change is less than 2% in an hour. A periodically poled LiNbOa (PPLN) was used as outer cavity frequency-doubling crystal and 561-nm laser was observed.

  11. ^3He neutron spin filters for polarized neutron scattering. (United States)

    Chen, Wangchun; Borchers, Julie; Chen, Ying; O'Donovan, Kevin; Erwin, Ross; Lynn, Jeffrey; Majkrzak, Charles; McKenney, Sarah; Gentile, Thomas


    Polarized neutron scattering (PNS) is a powerful tool that probes the magnetic structures in a wide variety of magnetic materials. Polarized ^3He gas, produced by optical pumping, can be used to polarize or analyze neutron beams because of the strong spin dependence of the neutron absorption cross section for ^3He. Polarized ^3He neutron spin filters (NSF) have been of great interest in PNS community due to recent significant improvement of their performance. Here I will discuss successful applications using ^3He NSFs in polarized neutron reflectometry (PNR) and triple-axis spectrometry (TAS). In PNR, a ^3He NSF in conjunction with a position-sensitive detector allows for efficient polarization analysis of off-specular scattering over a broad range of reciprocal space. In TAS, a ^3He NSF in combination with a double focusing pyrolytic graphite monochromator provides greater versatility and higher intensity compared to a Heusler polarizer. Finally I will present the results from patterned magnetically-coupled thin films in PNR and our first ``proof-of-principle'' experiment in TAS, both of which were performed using ^3He NSF(s) at the NIST Center for Neutron Research.

  12. Nuclear-Pumped Lasers. [efficient conversion of energy liberated in nuclear reactions to coherent radiation (United States)


    The state of the art in nuclear pumped lasers is reviewed. Nuclear pumped laser modeling, nuclear volume and foil excitation of laser plasmas, proton beam simulations, nuclear flashlamp excitation, and reactor laser systems studies are covered.

  13. High brightness diode-pumped organic solid-state laser

    CERN Document Server

    Zhao, Zhuang; Nafa, Malik; Chénais, Sébastien; Forget, Sébastien


    High-power, diffraction-limited organic solid-state laser operation has been achieved in a vertical external cavity surface-emitting organic laser (VECSOL), pumped by a low-cost compact blue laser diode. The diode-pumped VECSOLs were demonstrated with various dyes in a polymer matrix, leading to laser emissions from 540 nm to 660 nm. Optimization of both the pump pulse duration and output coupling leads to a pump slope efficiency of 11% for a DCM based VECSOLs. We report output pulse energy up to 280 nJ with 100 ns long pump pulses, leading to a peak power of 3.5 W in a circularly symmetric, diffraction-limited beam.

  14. High brightness diode-pumped organic solid-state laser (United States)

    Zhao, Zhuang; Mhibik, Oussama; Nafa, Malik; Chénais, Sébastien; Forget, Sébastien


    High-power, diffraction-limited organic solid-state laser operation has been achieved in a vertical external cavity surface-emitting organic laser (VECSOL), pumped by a low-cost compact blue laser diode. The diode-pumped VECSOLs were demonstrated with various dyes in a polymer matrix, leading to laser emissions from 540 nm to 660 nm. Optimization of both the pump pulse duration and output coupling leads to a pump slope efficiency of 11% for a DCM based VECSOLs. We report output pulse energy up to 280 nJ with 100 ns long pump pulses, leading to a peak power of 3.5 W in a circularly symmetric, diffraction-limited beam.

  15. DPSS Laser Beam Quality Optimization Through Pump Current Tuning

    Energy Technology Data Exchange (ETDEWEB)

    Omohundro, Rob; /Newport Spectra-Physics, Santa Clara; Callen, Alice; /SLAC; Sukuta, Sydney; /San Jose City Coll.


    The goal of this study is to demonstrate how a DPSS laser beam's quality parameters can be simultaneously optimized through pump current tuning. Two DPSS lasers of the same make and model were used where the laser diode pump current was first varied to ascertain the lowest RMS noise region. The lowest noise was found to be 0.13% in this region and the best M{sup 2} value of 1.0 and highest laser output power were simultaneously attained at the same current point. The laser manufacturer reported a M{sup 2} value of 1.3 and RMS noise value of .14% for these lasers. This study therefore demonstrates that pump current tuning a DPSS laser can simultaneously optimize RMS Noise, Power and M{sup 2} values. Future studies will strive to broaden the scope of the beam quality parameters impacted by current tuning.

  16. Analysis of Thermal Effects in Laser Rod Pumped by Repetitively Pulsed Laser Diode Array

    Institute of Scientific and Technical Information of China (English)

    DAI Qin; LI Xin-zhong; WU Ri-na; WANG Xi-jun


    Based on some assumptions, the numerical model of thermal distribution in solid state laser crystal pumped by pulsed laser diode is set up due to the pumped intensity distribution. Taking into account the property of YAG materials that varies with temperature, the transient temperature distribution of the laser crystal is calculated using finite element method on condition that K is a constant and a function of temperature. Then, the influence of the pumping parameters on the thermal effect in laser crystal is also discussed. This study is helpful to optimize the design of the diode side pumped solid state lasers.

  17. Wave optics simulation of diode pumped alkali laser (DPAL) (United States)

    Endo, Masamori; Nagaoka, Ryuji; Nagaoka, Hiroki; Nagai, Toru; Wani, Fumio


    A numerical simulation code for a diode pumped alkali laser (DPAL) was developed. The code employs the Fresnel- Kirchhoff diffraction integral for both laser mode and pump light propagations. A three-dimensional rate equation set was developed to determine the local gain. The spectral divergence of the pump beam was represented by a series of monochromatic beams with different wavelengths. The calculated results showed an excellent agreements with relevant experimental results. It was found that the main channel of the pump power drain is the spontaneous emission from the upper level of the lasing transition.

  18. Taming random lasers through active spatial control of the pump. (United States)

    Bachelard, N; Andreasen, J; Gigan, S; Sebbah, P


    Active control of the spatial pump profile is proposed to exercise control over random laser emission. We demonstrate numerically the selection of any desired lasing mode from the emission spectrum. An iterative optimization method is employed, first in the regime of strong scattering where modes are spatially localized and can be easily selected using local pumping. Remarkably, this method works efficiently even in the weakly scattering regime, where strong spatial overlap of the modes precludes spatial selectivity. A complex optimized pump profile is found, which selects the desired lasing mode at the expense of others, thus demonstrating the potential of pump shaping for robust and controllable single mode operation of a random laser.

  19. Taming random lasers through active spatial control of the pump

    CERN Document Server

    Bachelard, Nicolas; Gigan, Sylvain; Sebbah, Patrick


    Active control of the pump spatial profile is proposed to exercise control over random laser emission. We demonstrate numerically the selection of any desired lasing mode from the emission spectrum. An iterative optimization method is employed, first in the regime of strong scattering where modes are spatially localized and can be easily selected using local pumping. Remarkably, this method works efficiently even in the weakly scattering regime, where strong spatial overlap of the modes precludes spatial selectivity. A complex optimized pump profile is found, which selects the desired lasing mode at the expense of others, thus demonstrating the potential of pump shaping for robust and controllable singlemode operation of a random laser.

  20. Frequency-doubled diode laser for direct pumping of Ti:sapphire lasers

    DEFF Research Database (Denmark)

    Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika


    A single-pass frequency doubled high-power tapered diode laser emitting nearly 1.3 W of green light suitable for direct pumping of Ti:sapphire lasers generating ultrashort pulses is demonstrated. The pump efficiencies reached 75 % of the values achieved with a commercial solid-state pump laser....... However, the superior electro-optical efficiency of the diode laser improves the overall efficiency of the Ti:sapphire laser by a factor > 2. The optical spectrum emitted by the Ti:sapphire laser shows a spectral width of 112 nm (FWHM). Based on autocorrelation measurements, pulse widths of less than 20...... fs are measured. These results open the opportunity of establishing diode laser pumped Ti:sapphire lasers for e.g. biophotonic applications like retinal optical coherence tomography or pumping of photonic crystal fibers for CARS microscopy....

  1. Thin-disk laser pump schemes for large number of passes and moderate pump source quality (United States)

    Schuhmann, Karsten; Hänsch, Theodor W.; Kirch, Klaus; Knecht, Andreas; Kottmann, Franz; Nez, Francois; Pohl, Randolf; Taqqu, David; Antognini, Aldo


    Novel thin-disk laser pump layouts are proposed yielding an increased number of passes for a given pump module size and pump source quality. These novel layouts result from a general scheme which bases on merging two simpler pump optics arrangements. Some peculiar examples can be realized by adapting standard commercially available pump optics simply by intro ducing an additional mirror-pair. More pump passes yield better efficiency, opening the way for usage of active materials with low absorption. In a standard multi-pass pump design, scaling of the number of beam passes brings ab out an increase of the overall size of the optical arrangement or an increase of the pump source quality requirements. Such increases are minimized in our scheme, making them eligible for industrial applications

  2. Thin-disk laser pump schemes for large number of passes and moderate pump source quality. (United States)

    Schuhmann, Karsten; Hänsch, Theodor W; Kirch, Klaus; Knecht, Andreas; Kottmann, Franz; Nez, Francois; Pohl, Randolf; Taqqu, David; Antognini, Aldo


    Thin-disk laser pump layouts yielding an increased number of passes for a given pump module size and pump source quality are proposed. These layouts result from a general scheme based on merging two simpler pump optics arrangements. Some peculiar examples can be realized by adapting standard, commercially available pump optics with an additional mirror pair. More pump passes yield better efficiency, opening the way for the usage of active materials with low absorption. In a standard multipass pump design, scaling of the number of beam passes brings about an increase in the overall size of the optical arrangement or an increase in the pump source quality requirements. Such increases are minimized in our scheme, making them eligible for industrial applications.

  3. Thin-disk laser pump schemes for large number of passes and moderate pump source quality

    CERN Document Server

    Schuhmann, K; Kirch, K; Knecht, A; Kottmann, F; Nez, F; Pohl, R; Taqqu, D; Antognini, A


    Novel thin-disk laser pump layouts are proposed yielding an increased number of passes for a given pump module size and pump source quality. These novel layouts result from a general scheme which bases on merging two simpler pump optics arrangements. Some peculiar examples can be realized by adapting standard commercially available pump optics simply by intro ducing an additional mirror-pair. More pump passes yield better efficiency, opening the way for usage of active materials with low absorption. In a standard multi-pass pump design, scaling of the number of beam passes brings ab out an increase of the overall size of the optical arrangement or an increase of the pump source quality requirements. Such increases are minimized in our scheme, making them eligible for industrial applications

  4. A Laser-Diode End-Pumped Nd:YVO4 Slab Laser at 1342 nm

    Institute of Scientific and Technical Information of China (English)

    YAN Ying; ZHANG Heng-Li; LIU Yang; XING Ji-Chuan; XIN Jian-Guo


    A laser-diode end-pumped Nd:YV04 slab laser with a fiat-concave stable cavity at 1342nm is demonstrated. Under the pumping power of 92 W, a cw laser of output 17.8 W is obtained with the slope efficiency of 25.6%.

  5. Efficient Ho:YLF laser pumped by a Tm:fiber laser

    CSIR Research Space (South Africa)

    Koen, W


    Full Text Available A thulium fiber laser pumped Ho:YLF laser delivering 45.1 W in a near diffraction limited beam when pumped with 84.7 W is demonstrated. The optical-to-optical efficiency of 53 % compares favorably with similar Ho:YAG lasers....

  6. Assignment of the /Li-7/2 optically pumped laser transitions pumped by Ar/+/ and Kr/+/ laser lines (United States)

    Verma, K. K.; Stwalley, W. C.; Zemke, W. T.


    Welling and Wellegehausen (1977) have reported a list of Na2 and Li2 lines (belonging to B-X and A-X systems) which lase when vapors of these dimers are pumped with an Ar(+) or Kr(+) laser. A description is presented of a fluorescence study of the A-X system of the (Li-7)2 molecule excited by a Kr(+) laser (6471 A). The optically pumped laser lines are identified as P and R doublets in two different fluorescence series. The conditions which favor lasing action of these lines are pointed out. All but one of the known optically pumped laser lines of (Li-7)2 along with their assignments are presented in a table. For each pumping line, several additional wavelengths are listed which satisfy the condition for laser oscillations and which might well lase well under slightly improved conditions.

  7. Laser-diode-pumped 1319-nm monolithic non-planar ring single-frequency laser

    Institute of Scientific and Technical Information of China (English)

    Qing Wang(王青); Chunqing Gao(高春清); Yan Zhao(赵严); Suhui Yang(杨苏辉); Guanghui Wei(魏光辉); Dongmei Hong(洪冬梅)


    Single-frequency 1319-nm laser was obtained by using a laser-diode-pumped monolithic Nd:YAG crystalwith a non-planar ring oscillator (NPRO). When the NPRO laser was pumped by an 800-μm fiber coupledlaser diode, the output power of the single-frequency 1319-nm laser was 220 mW, and the slope efficiencywas 16%. With a 100-μm fiber coupled diode laser pumped, 99-mW single-frequency 1319-nm laser wasobtained with a slope efficiency of 29%.

  8. Intensity scaling of an optically pumped potassium laser (United States)

    Hurd, Edward J.; Holtgrave, Jeremy C.; Perram, Glen P.


    A pulsed, optically pumped potassium laser has been demonstrated with output intensity exceeding 7 MW/cm2. By using a surrogate pump, heat pipe gain cell, and helium pressure of 2500 Torr, the intensity of Diode Pumped Alkali Lasers (DPAL) has been increased by a factor of 38. Bottlenecking due to slow fine structure mixing can be avoided without hydrocarbon buffer gases with as many as 375 lasing photons obtained per potassium atom following a 7.4 ns pump pulse. A slope efficiency of 9.4% is achieved and primarily limited by a mismatch between pumped and cavity mode volumes. Laser performance is well described by a three-level, longitudinally averaged model without ionization.

  9. Polarization properties of laser-diode-pumped micro-grained Nd:YAG ceramic lasers

    CERN Document Server

    Otsuka, Kenju


    Detailed polarization properties have been examined in laser-diode-pumped (LD-pumped) micro-grained ceramic Nd:YAG lasers in different microchip cavity configurations. Stable linearly-polarized single-frequency oscillations, whose polarization direction coincides with that of an LD pump light, were observed in an external cavity scheme. While, in the case of a thin-slice laser scheme with coated reflective ends, elliptically-polarized single-frequency operations took place in the low pump-power regime and dynamic instabilities appeared, featuring self-induced antiphase modulations among counter-rotating circularly-polarized components belonging to the same longitudinal mode, with increasing the pump power

  10. 3He melting pressure temperature scale

    DEFF Research Database (Denmark)

    Halperin, W.P.; Archie, C.N.; Richardson, R.C.


    The latent heat for solidification of **3He has been measured along the **3He melting curve between 23 and 1 mK. A temperature scale is established which depends only on measurements of heat, pressure and volume, and on the condition that the entropy of solid **3He approaches R ln 2 at high...

  11. Mathematical model of an optically pumped molecular laser

    CSIR Research Space (South Africa)

    Botha, LR


    Full Text Available pumped molecular laser Dr L R Botha, Dr C Bollig, D Esser, C Jacobs, D Preussler SAIP 2009 Durban Page 2 © CSIR 2008 Structure of talk • Introduction • Overview of HBr laser • Numerical Model • Comparison... µm laser ring oscillator & pre-amplifier 1.9 µm Optically Pumped Molecular laser @ 4 µm 95:5 HBr Absorption cell Fast detector 2.064 µm ± 1 nm Feedback control box Feedback loop 1 P ie zo m o u nt Fast detector Feedback loop 2 Gas...

  12. Picosecond holmium fibre laser pumped at 1125 \\ {\\text{nm}} (United States)

    Kamynin, V. A.; Filatova, S. A.; Zhluktova, I. V.; Tsvetkov, V. B.


    We report a passively mode-locked, all-fibre holmium laser based on nonlinear polarisation rotation. As a pump source use is made of an 1125-{\\text{nm}} ytterbium-doped fibre laser. The pulse repetition rate of the holmium laser is 7.5 {\\text{MHz}}, and the pulse duration does not exceed 52 {\\text{ps}} at wavelengths of 2065 and 2080 {\\text{nm}}. The average laser output power reaches 5 {\\text{mW}}.

  13. Plasma formation in diode pumped alkali lasers sustained in Cs (United States)

    Markosyan, Aram H.; Kushner, Mark J.


    In diode pumped alkali lasers (DPALs), lasing action occurs on the resonant lines of alkali atoms following pumping by broadband semiconductor lasers. The goal is to convert the efficient but usually poor optical quality of inexpensive diode lasers into the high optical quality of atomic vapor lasers. Resonant excitation of alkali vapor leads to plasma formation through the excitation transfer from the 2P states to upper lying states, which then are photoionized by the pump and intracavity radiation. A first principles global model was developed to investigate the operation of the He/Cs DPAL system and the consequences of plasma formation on the efficiency of the laser. Over a range of pump powers, cell temperatures, excitation frequency, and mole fraction of the collision mixing agent (N2 or C2H6), we found that sufficient plasma formation can occur that the Cs vapor is depleted. Although N2 is not a favored collisional mixing agent due to large rates of quenching of the 2P states, we found a range of pump parameters where laser oscillation may occur. The poor performance of N2 buffered systems may be explained in part by plasma formation. We found that during the operation of the DPAL system with N2 as the collisional mixing agent, plasma formation is in excess of 1014-1015 cm-3, which can degrade laser output intensity by both depletion of the neutral vapor and electron collisional mixing of the laser levels.

  14. Continuous-wave Raman laser pumped within a semiconductor disk laser cavity. (United States)

    Parrotta, Daniele C; Lubeigt, Walter; Kemp, Alan J; Burns, David; Dawson, Martin D; Hastie, Jennifer E


    A KGd(WO₄)₂ Raman laser was pumped within the cavity of a cw diode-pumped InGaAs semiconductor disk laser (SDL). The Raman laser threshold was reached for 5.6 W of absorbed diode pump power, and output power up to 0.8 W at 1143 nm, with optical conversion efficiency of 7.5% with respect to the absorbed diode pump power, was demonstrated. Tuning the SDL resulted in tuning of the Raman laser output between 1133 and 1157 nm.

  15. Proposed Nuclear Pumped Laser Experiments Utilizing Gamma-Rays. (United States)


    geometrica factor. The geometrical factor was derived in 21 geometry. The probability of a photon born in the LXe intersecting the laser tube is e - . 2wr dr...the absorbing media is pumped by a slowly rising pump, the excitation is rapidly degraded due to spontaneous emission and quenching processes. If the

  16. Efficient potassium diode pumped alkali laser operating in pulsed mode. (United States)

    Zhdanov, Boris V; Rotondaro, Matthew D; Shaffer, Michael K; Knize, Randall J


    This paper presents the results of our experiments on the development of an efficient hydrocarbon free diode pumped alkali laser based on potassium vapor buffered by He gas at 600 Torr. A slope efficiency of more than 50% was demonstrated with a total optical conversion efficiency of 30%. This result was achieved by using a narrowband diode laser stack as the pump source. The stack was operated in pulsed mode to avoid limiting thermal effects and ionization.

  17. 600-W lamp pumped CW Nd:YAG laser

    Institute of Scientific and Technical Information of China (English)

    Qiang Li(李强); Zhimin Wang(王志敏); Zhiyong Wang(王智勇); Zhensheng Yu(于振声); Hong Lei(雷訇); Jiang Guo(郭江); Gang Li(李港); Tiechuan Zuo(左铁钏)


    A lamp pumped CW Nd:YAG laser is presented in this paper for the requirement of industrial application.The main factors, which affect output power and beam quality of high power solid-state laser module, are theoretically analyzed. Total electro-optics efficiency of lamp pumped Nd:YAG crystal as high as 4.0% is obtained, and output power is higher than 647 W with beam parameter product 22 mm.mrad.

  18. Pump polarization insensitive and efficient laser-diode pumped Yb:KYW ultrafast oscillator. (United States)

    Wang, Sha; Wang, Yan-Biao; Feng, Guo-Ying; Zhou, Shou-Huan


    We theoretically and experimentally report and evaluate a novel split laser-diode (LD) double-end pumped Yb:KYW ultrafast oscillator aimed at improving the performance of an ultrafast laser. Compared to a conventional unpolarized single-LD end-pumped ultrafast laser system, we improve the laser performance such as absorption efficiency, slope efficiency, cw mode-locking threshold, and output power by this new structure LD-pumped Yb:KYW ultrafast laser. Experiments were carried out with a 1 W output fiber-coupled LD. Experimental results show that the absorption increases from 38.7% to 48.4%, laser slope efficiency increases from 18.3% to 24.2%, cw mode-locking threshold decreases 12.7% from 630 to 550 mW in cw mode-locking threshold, and maximum output-power increases 28.5% from 158.4 to 221.5 mW when we switch the pump scheme from an unpolarized single-end pumping structure to a split LD double-end pumping structure.

  19. Stable 811.53 nm diode laser pump source for optically pumped metastable Ar laser (United States)

    Gao, Jun; Zuo, Duluo; Zhao, Jun; Li, Bin; Yu, Anlan; Wang, Xinbing


    A stable external cavity diode laser coupled with volume Bragg grating for metastable argon atoms pumping is presented. The measured maximum output power of the continuous wave is 6.5 W when the spectral width (FWHM) is less than 21 pm around 811.53 nm and the power efficiency is 68%. The tuning range of the emission wavelength is bigger than 270 pm. The calculated deviation in relative absorption efficiency caused by the fluctuations of wavelength and power is less than 4%.

  20. The Panofsky ratio in 3He (United States)

    Corriveau, F.; Hasinoff, M. D.; Measday, D. F.; Poutissou, J.-M.; Salomon, M.


    The branching ratios have been measured for γ-ray channels produced by π- stopping in liquid 3He. The results for the Panofsky ratio are P3 = ω( π-3He → π0t)/ ω( π-3He → γt) = 2.83 ± 0.07, and for the ratio of the radiative breakup channels, B3 = ω)( π-3He → γnd + γnnp)/ ω( π-3He → γt) = 1.35 ±0.11.

  1. Comparison of different side-pumping configurations for high power laser diode pumped solid-state laser

    Institute of Scientific and Technical Information of China (English)

    Junqing Meng(孟俊清); Weibiao Chen(陈卫标); Xia Hou(侯霞); Qiquan Hu(胡企铨)


    Ray-tracing method is used to simulate the distribution of absorption in crystal rod for different sidepumping configuration. The distribution of pumping power and absorption efficiency is compared, and the numerical results are presented. The results show that the more uniform pumping and the higher absorption coefficient are obtained with a diffuse cavity. And the method of the slow axis of laser diode stack perpendicular to the axis of lasing gives the higher central pumping density.

  2. Diode-pumped Alexandrite ring laser for lidar applications (United States)

    Munk, A.; Jungbluth, B.; Strotkamp, M.; Hoffmann, H.-D.; Poprawe, R.; Höffner, J.


    We present design and performance data of a diode-pumped Q-switched Alexandrite ring laser in the millijoule regime, which is longitudinally pumped by laser diode bar modules in the red spectral range. As a first step, a linear resonator was designed and characterized in qcw operation as well as in Q-switched operation. Based on these investigations, two separate linear cavities were set up, each with one Alexandrite crystal longitudinally pumped by one diode module. The two cavities are fused together and form a ring cavity which yields up to 6 mJ pulse burst energy in the qcw regime at 770 nm.

  3. Direct pumping of ultrashort Ti:sapphire lasers by a frequency doubled diode laser

    DEFF Research Database (Denmark)

    Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika


    electro-optical efficiency of the diode laser. Autocorrelation measurements show that pulse widths of less than 20 fs can be expected with an average power of 52 mW when using our laser. These results indicate the high potential of direct diode laser pumped Ti: sapphire lasers to be used in applications...... like retinal optical coherence tomography (OCT) or pumping of photonic crystal fibers for CARS (coherent anti-stokes Raman spectroscopy) microscopy....

  4. Analysis of Laser Diode Pumped Solid-State Laser Resonator by the Transform Circle Approach

    Institute of Scientific and Technical Information of China (English)

    SONG Feng; ZHANG Guang-Yin; XU Jing-Jun; ZHANG Chao-Bo


    The typical laser characteristics of a laser diode pumped solid-state laser with a Z-type resonator structure are analyzed by the transform circle approach. Laser waists change with the thermal focus length of the lasing medium so that the output power becomes unstable. In particular, there is a very unstable operation region when the pump power is of medium magnitude. A method is put forward to avoid this situation.

  5. Four-Pass Coupler for Laser-Diode-Pumped Solid-State Laser (United States)

    Coyle, Donald B.


    A four-pass optical coupler affords increased (in comparison with related prior two-pass optical couplers) utilization of light generated by a laser diode in side pumping of a solid-state laser slab. The original application for which this coupler was conceived involves a neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal slab, which, when pumped by a row of laser diodes at a wavelength of 809 nm, lases at a wavelength of 1,064 nm. Heretofore, typically, a thin laser slab has been pumped in two passes, the second pass occurring by virtue of reflection of pump light from a highly reflective thin film on the side opposite the side through which the pump light enters. In two-pass pumping, a Nd:YAG slab having a thickness of 2 mm (which is typical) absorbs about 84 percent of the 809-nm pump light power, leaving about 16 percent of the pump light power to travel back toward the laser diodes. This unused power can cause localized heating of the laser diodes, thereby reducing their lifetimes. Moreover, if the slab is thinner than 2 mm, then even more unused power travels back toward the laser diodes. The four-pass optical coupler captures most of this unused pump light and sends it back to the laser slab for two more passes. As a result, the slab absorbs more pump light, as though it were twice as thick. The gain and laser cavity beam quality of a smaller laser slab in conjunction with this optical coupler can thus be made comparable to those of a larger two-pass-pumped laser slab.

  6. Polarization measurement of Cs using the pump laser beam

    CERN Document Server

    Fang, Jiancheng; Duan, Lihong; Fan, Wenfeng; Jiang, Liwei


    In the optical pumping systems based on the pump-probe arrangement, the spin polarization of the atoms is generally monitored utilizing the probe laser beam, in which way an extra perturbation must be introduced and thus affects the normal operation of the sensors. By investigating the absorption rate of the circularly polarized pump laser, here we demonstrate the feasibility of extracting the electron-spin polarization from the transmitted pump laser intensity. We experimentally validate the method in a spin-exchange relaxation free (SERF) magnetometer and the results are in excellent agreement with the theory. The scheme operates in a silent mode and features a real-time observation. We also study the corresponding magnetic field response of the SERF magnetometer and a term arising from the diffusion effects has been added to the original model to explain the discrepancy of the response.

  7. Dichroic mirror for diode pumped YAG:Nd-laser

    DEFF Research Database (Denmark)

    Dinca, Andreea; Skettrup, Torben; Lupei, V.


    The paper describes the design and realization of a dichroic mirror for a diode pumped YAG:Nd laser. The mirror is deposed on an optical glass substrate and works in optical contact with the laser crystal. The design was performed by admittance matching of the basic stack with the adjacent media...

  8. LD-pumped Ho,Tm:YLF microchip laser

    Institute of Scientific and Technical Information of China (English)

    SUN Jing-hua; ZHANG Xin-lu


    A simple rate equation model for 2μm Tm,Ho:YLF laser is given to study laser dynamics. Under low pump power, the explicit formulae for the threshold pump power and the relation between output power and incident power are obtained. The present model provides a straightforward procedure to design the laser resonator and the optical coupling system for optimization. At the same time, the experimental results are reported. At room temperature the slope efficiency is 22.4% and the typical lasing threshold is about 328mW. The theory is in good agreement with experiment.

  9. Q-switched Ho:YLF laser pumped by a Tm:GdVO4 laser.

    CSIR Research Space (South Africa)

    Esser, MJD


    Full Text Available The authors have, through careful analysis of spectroscopic data, designed and demonstrated a diode-end-pumped, quasicontinuous wave Tm:GdVO4 laser operating at 1892 nm in order to pump a Q-switched Ho:YLF laser. The Ho:YLF maximum output energy...

  10. Tapered Diode-pumped continuous-wave alexandrite laser



    Tapered diode-pumped continuous-wave alexandrite laser Ersen Beyatli,1 Ilyes Baali,2 Bernd Sumpf,3 Götz Erbert,3 Alfred Leitenstorfer,4 Alphan Sennaroglu,1 and Umit Demirbas2,4,* 1Laser Research Laboratory, Departments of Physics and Electrical-Electronics Engineering, Koç University, Rumelifeneri, Sariyer, Istanbul 34450, Turkey 2Laser Technology Laboratory, Department of Electrical and Electronics Engineering, Antalya International University, 07190 Dosemealti, Antalya,...

  11. End-Pumped Tm:YAG Ceramic Slab Lasers

    Institute of Scientific and Technical Information of China (English)

    CHENG Xiao-Jin; XU Jian-Qiu; ZHANG Wen-Xin; JIANG Sen-Xue; PAN Yu-Bai


    Lasers from a Tm:YAG ceramic aare reported for the first time to our best knowledge. The Tm:YAG ceramic slab is end-pumped by a laser diode with central wavelength 792nm. At room temperature, the maximum continuous-wave output power is 4.5 W, and the sloping efficiency is obtained to be 20.5%. The laser spectrum of the Tm: YAG ceramic is centered at 2015 nm.

  12. Decoupling of Confined Normal 3He (United States)

    Dimov, S. G.; Bennett, R. G.; Ilic, B.; Verbridge, S. S.; Levitin, L. V.; Fefferman, A. D.; Casey, A.; Saunders, J.; Parpia, J. M.


    Anodic bonding was used to fabricate a 10 mm diameter × 640 nm tall annular geometry suitable for torsion pendulum studies of confined 3He. For pure 3He at saturated vapor pressure the inertia of the confined fluid was seen to be only partially coupled to the pendulum at 160 mK. Below 100 mK the liquid’s inertial contribution was negligible, indicating a complete decoupling of the 3He from the pendulum.

  13. High-Efficiency High-Power Nd:YAG Laser under 885 nm Laser Diode Pumping

    Institute of Scientific and Technical Information of China (English)

    LI Fang-Qin; ZHANG Xiao-Fu; ZONG Nan; YANG Jing; PENG Qin-Jun; CUI Da-Fu; XU Zu-Yan


    A high-efficiency high-power Nd:YAG laser under 885 nm laser diode (LD) pumping is demonstrated. The laser crystal is carefully designed, and the overlapping between the pump modes and the laser modes is optimized. The maximum output power at 1064 nm is 87 W under the absorbed pump power 127.7 W, corresponding to a slope efficiency of 72.4% and an optical-optical efficiency of 68.1%. The optical-optical efficiency is 58.4% for the pump power emitted directly from the LD. To our best knowledge, this is the maximal optical-optical conversion efficiency obtained for the LD end-pumped Nd:YAG lasers so far.

  14. Investigation of radial temperature gradients in diode pumped alkali lasers using tunable diode laser absorption spectroscopy (United States)

    Fox, Charles D.; Perram, Glen P.


    Heat loads in Diode Pumped Alkali Lasers (DPAL) have been investigated using a diode laser to probe the radial dependence of the absorbance. A TiS pump laser heats the medium in a T=50-100°C cesium heat pipe with 5 Torr nitrogen used for quenching. A tunable diode laser probes the spectral absorbance of the cesium cell. Local alkali concentration, temperature, and saturation broadening modify Voigt lineshapes in the wing of the hyperfine split lines. The temperature within the pumped volume exceeds the wall temperature by almost 200 C.

  15. Continuously tunable solution-processed organic semiconductor DFB lasers pumped by laser diode

    DEFF Research Database (Denmark)

    Klinkhammer, Sönke; Liu, Xin; Huska, Klaus


    solutions on cm-scale surface gratings of different periods. We report optically pumped continuously tunable laser emission of 13 nm in the blue, 16 nm in the green and 19 nm in the red spectral region on a single chip respectively. Tuning behavior can be described with the Bragg-equation and the measured...... thickness profile. The laser threshold is low enough that inexpensive laser diodes can be used as pump sources....

  16. Ti:sapphire laser with long-pulse lamp pumping (United States)

    Koselja, Michael P.; Kubelka, Jiri; Kvapil, Jiri


    Lamp pumping of Ti:Sapphire has some advantages over laser pumping and represents some interest due to possible applications. The paper will present laser behavior of Ti:Sapphire under very long lamp pulse pumping. Pulse lamp duration (FWHM) was more than 100 times greater than the lifetime of Ti3+. Output energy with no tuning element was achieved greater than 1.5 J with 0.12% electrical-to-optical efficiency. Dimensions of the rod used was 7 mm in diameter and 148 mm in length. The doping level of Ti3+ was 0.09% Ti2O3 in the rod. Tuning characteristics with different tuning elements are also presented. Further development to obtain CW lamp pumping operation will be discussed.

  17. Pump-Controlled Modal Interactions in Microdisk Lasers

    CERN Document Server

    Liew, Seng Fatt; Redding, Brandon; Solomon, Glenn S; Cao, Hui


    We demonstrate an effective control of nonlinear interactions of lasing modes in a semiconductor microdisk cavity by shaping the pump profile. A target mode is selected at the expense of its competing modes either by increasing their lasing thresholds or suppressing their power slopes above the lasing threshold. Despite of strong spatial overlap of the lasing modes at the disk boundary, adaptive pumping enables an efficient selection of any lasing mode to be the dominant one, leading to a switch of lasing frequency. The theoretical analysis illustrates both linear and nonlinear effects of selective pumping, and quantify their contributions to lasing mode selection. This work shows that adaptive pumping not only provides a powerful tool of controlling the nonlinear process in multimode lasers, but also enables the tuning of lasing characteristic after the lasers have been fabricated.

  18. 980nm diode laser pump modules operating at high temperature (United States)

    Campbell, Jenna; Semenic, Tadej; Leisher, Paul; Bhunia, Avijit; Mashanovitch, Milan; Renner, Daniel


    Existing thermal management technologies for diode laser pumps place a significant load on the size, weight and power consumption of High Power Solid State and Fiber Laser systems, thus making current laser systems very large, heavy, and inefficient in many important practical applications. This problem is being addressed by the team formed by Freedom Photonics and Teledyne Scientific through the development of novel high power laser chip array architectures that can operate with high efficiency when cooled with coolants at temperatures higher than 50 degrees Celsius and also the development of an advanced thermal management system for efficient heat extraction from the laser chip array. This paper will present experimental results for the optical, electrical and thermal characteristics of 980 nm diode laser pump modules operating effectively with liquid coolant at temperatures above 50 degrees Celsius, showing a very small change in performance as the operating temperature increases from 20 to 50 degrees Celsius. These pump modules can achieve output power of many Watts per array lasing element with an operating Wall-Plug-Efficiency (WPE) of >55% at elevated coolant temperatures. The paper will also discuss the technical approach that has enabled this high level of pump module performance and opportunities for further improvement.

  19. Optically pumped terahertz lasers with high pulse repetition frequency: theory and design

    Institute of Scientific and Technical Information of China (English)

    Yude Sun; Shiyou Fu; Jing Wang; Zhenghe Sun; Yanchao Zhang; Zhaoshuo Tian; Qi Wang


    Optically pumped terahertz (THz) lasers with high pulse repetition frequency are designed. Such a laser includes two parts: the optically pumping laser and the THz laser. The structures of the laser are described and analyzed. The rate equations for the pulsed THz laser are given. The kinetic process and laser pulse waveform for this kind of laser are numerically calculated based on the theory of rate equations. The theoretical results give a helpful guide to the research of such lasers.

  20. Transverse Mode Formation in Longitudinally Pumped Miniature Slab Lasers

    Institute of Scientific and Technical Information of China (English)

    XU Jian-Qiu; YE Xin; FANG Tao


    The formation of transverse modes in longitudinally pumped miniature slab lasers is investigated theoretically and experimentally. The longitudinally non-uniform gain-guiding is studied by expanding the electric field into the Hermite-Gaussian functions that satisfy boundary conditions of the resonator. Non-Gaussian transversal beam profiles in the near field are found and the beam diameter is reduced when the pump spot becomes smaller. The experimental observation agrees with the theoretical calculation.

  1. 372-mJ long pulse pyrotechnically pumped laser

    Institute of Scientific and Technical Information of China (English)

    Nan Xiao; Zongfu Jiang; Weihong Hua; Shengfu Yuan


    A pyrotechnically pumped Nd glass laser is demonstrated by the use of pyrotechnic flashlamps composed of several chemical materials arranged in a stable plane concave resonator cavity. The flashlamp was made of chemical mixture with oxidant, fuel, and binder. The emission spectrum of pyrotechnic flame covered most of the absorption bands of Nd3+ in phosphate glass. Under 4.56-g chemical mixture pumping, long pulse output power of about 5.5 W was achieved.

  2. Tandem-pumped 1120-nm actively Q-switched fiber laser

    Institute of Scientific and Technical Information of China (English)

    王建华; 胡金萌; 张世强; 陈露璐; 房勇; 冯衍


    We report on a tandem-pumped actively Q-switched fiber laser system emitting at 1120 nm. Parasitic oscillation is challenging in Yb-doped Q-switched 1120-nm fiber laser, which is suppressed by pumping with a fiber laser at 1018 nm. At least 4 times improvement in output peak power is demonstrated in a single laser setup with 1018-nm fiber laser pumping instead of 976-nm laser diode pumping. This is, to the best of our knowledge, the first demonstration of a tandem-pumped Q-switched fiber laser.

  3. Scaling of an Optically Pumped Mid-Infrared Rubidium Laser (United States)


    model for alkali metal vapor lasers : part I. Narrowband optical pumping.” Applied Physics B 101, No. 1-2, 45-56 (2010). W. Klennert, “ overview,” High-Power Laser Ablation 2008. International Society for Optics and Photonics, 700521 (2008). 64 W.F. Krupke and others, “New...Physics B 89, No. 4, 595-601 (2007). P.P. Sorokin and J.R. Lankard, “Infrared Lasers Resulting from Giant Pulse Laser Excitation of Alkali Metal

  4. Laser-diode and Flash Lamp Pumped Solid-State Lasers (United States)

    Garrec, Bruno Le


    Since the early 80's, most authors are considering that to enable high-average-power operation at the highest laser efficiency, it is necessary to replace flash lamp pumped solid-state lasers with laser-diode pumped solid-state lasers. This assumption is based on the fact that diode pumping has many advantages compared to flash lamp pumping that is seen as an old technology. Although it is very difficult to get true numbers, we shall show that Diode Pumped Solid State Lasers nearby the kW level have a moderate efficiency (Flash lamp pumped fusion lasers are still in the run with a low efficiency but can access high beam quality and high harmonic generation efficiency. For the ELI project, we believe that considering a flash lamp pumped laser makes sense when the amplifier can run at 1 shot/mn to delivering 200J of green light. We shall show that it is an engineering problem to be solved with the help of: adaptive optic and large non linear crystals.

  5. Analyses of the short pulse laser pumped transient collisional excited X-ray lasers

    Energy Technology Data Exchange (ETDEWEB)

    Sasaki, A.; Utsumi, T.; Moribayashi, K.; Zhidkov, A.; Kado, M.; Tanaka, M.; Hasegawa, N.; Kawachi, T. [Japan Atomic Energy Research Inst., Osaka (Japan). Advanced Photon Research Center


    The soft X-ray gain of the transient collisional excited (TCE) Ni-like Ag laser is investigated using the plasma hydrodynamics and atomic kinetics codes. The gain is calculated for a plasma produced from two 100ps laser irradiated solid target to show qualitative agreement with the experiment. The calculation shows significant improvement of the gain using a thin foil target pumped by two short laser pulses, because of a better coupling of the pump laser energy into the gain region of the plasma. The codes will provide performance prediction as well as optimization of the experimental studies of the TCE X-ray lasers. (orig.)

  6. Nonlinear fibre-optic devices pumped by semiconductor disk lasers

    Energy Technology Data Exchange (ETDEWEB)

    Chamorovskiy, A Yu; Okhotnikov, Oleg G [Optoelectronics Research Center, Tampere University of Technology, Tampere (Finland)


    Semiconductor disk lasers offer a unique combination of characteristics that are particularly attractive for pumping Raman lasers and amplifiers. The advantages of disk lasers include a low relative noise intensity (-150 dB Hz{sup -1}), scalable (on the order of several watts) output power, and nearly diffraction-limited beam quality resulting in a high ({approx}70 % - 90 %) coupling efficiency into a single-mode fibre. Using this technology, low-noise fibre Raman amplifiers operating at 1.3 {mu}m in co-propagation configuration are developed. A hybrid Raman-bismuth doped fibre amplifier is proposed to further increase the pump conversion efficiency. The possibility of fabricating mode-locked picosecond fibre lasers operating under both normal and anomalous dispersion is shown experimentally. We demonstrate the operation of 1.38-{mu}m and 1.6-{mu}m passively mode-locked Raman fibre lasers pumped by 1.29-{mu}m and 1.48-{mu}m semiconductor disk lasers and producing 1.97- and 2.7-ps pulses, respectively. Using a picosecond semiconductor disk laser amplified with an ytterbium-erbium fibre amplifier, the supercontinuum generation spanning from 1.35 {mu}m to 2 {mu}m is achieved with an average power of 3.5 W. (invited paper)

  7. Diode-Pumped Mode-Locked LiSAF Laser

    Energy Technology Data Exchange (ETDEWEB)



    Under this contract we have developed Cr{sup 3+}:LiSrAlF{sub 6} (Cr:LiSAF, LiSAF) mode-locked lasers suitable for generation of polarized electrons for CEBAF. As 670 nm is an excellent wavelength for optical pumping of Cr:LiSAF, we have used a LIGHTWAVE developed 670 nm diode pump module that combines the output of ten diode lasers and yields approximately 2 Watts of optical power. By the use of a diffraction limited pump beam however, it is possible to maintain a small mode size through the length of the crystal and hence extract more power from Cr:LiSAF laser. For this purpose we have developed a 1 Watt, red 660nm laser (LIGHTWAVE model 240R) which serves as an ideal pump for Cr:LiSAF and is a potential replacement of costly and less robust krypton laser. This new system is to compliment LIGHTWAVE Series 240, and is currently being considered for commercialization. Partially developed under this contract is LIGHTWAVEs product model 240 which has already been in our production lines for a few months and is commercially available. This laser produces 2 Watts of output at 532 nm using some of the same technology developed for production of the 660nm red system. It is a potential replacement for argon ion lasers and has better current and cooling requirements and is an excellent pump source for Ti:Al{sub 2}O{sub 3}. Also, as a direct result of this contract we now have the capability of commercially developing a mode-locked 100MHz Cr:LiSAF system. Such a laser could be added to our 100 MHz LIGHTWAVE Series 131. The Series 131 lasers provide pico second pulses and were originally developed under another DOE SBIR. Both models of LIGHTWAVE Series 240 lasers, the fiber coupled pump module and the 100MHz LiSAF laser of Series 131 have been partially developed under this contract, and are commercially competitive products.

  8. The analytical investigation of temperature distribution in off-central diode-pumped lasers

    Indian Academy of Sciences (India)

    P Ealhi; A Taghavi; A Gharaati


    The influence of displacement of the pump source with respect to the crystal center on the thermal behavior of the laser crystal is studied analytically. We consider the pump energy to be deposited into the pump region which has been slightly displaced with respect to the crystal center. An analytical expression for temperature distribution for such off-central diode-pumped laser is investigated. The results are then applied to the Nd :YAG and Nd :YVO4 laser crystals and compared with the conventional diode-pumped lasers. We showed that in this special case, the temperature distribution equation in the off-central pumping convert to the conventional central pump scheme.

  9. Investigation of laser diode face-pumped high average power heat capacity laser

    Institute of Scientific and Technical Information of China (English)

    Shenjin Zhang; Shouhuan Zhou; Xiaojun Tang; Guojiang Bi; Huachang LV


    The three-dimensional (3D) pump intensity distribution in medium of the laser diode (LD) pumped highaverage power heat capacity laser is simulated by the ray tracing method, and the divergence characteristicsof fast axis and slow axis of LD are simultaneously considered. The transient 3D temperature and stressdistributions are also simulated by the finite element method (FEM) with considering the uneven heatsource distribution in medium. A LD face-pumped Nd:GGG heat capacity laser is designed. The averageoutput power is 1.49 kW with an optical-optical efficiency of 24.1%.

  10. LED pumped Nd:YAG laser development program (United States)

    Farmer, G. I.; Kiang, Y. C.; Lynch, R. J.


    The results of a development program for light emitting diode (LED) pumped Nd:YAG lasers are described. An index matching method to increase the coupling efficiency of the laser is described. A solid glass half-cylinder of 5.0 by 5.6 centimeters was used for index matching and also as a pumping cavity reflector. The laser rods were 1.5 by 56 millimeters with dielectric coatings on both end surfaces. The interfaces between the diode array, glass cylinder, and laser rod were filled with viscous fluid of refractive index n = 1.55. Experiments performed with both the glass cylinder and a gold coated stainless steel reflector of the same dimensions under the same operating conditions indicate that the index matching cylinder gave 159 to 200 percent improvement of coupling efficiency over the metal reflector at various operating temperatures.

  11. Advances in NASA research on nuclear-pumped lasers (United States)

    De Young, R. J.


    NASA has been primarily interested in nuclear-pumped lasers using the He-3 or U-235F6 reaction for lasant excitation. With He-3 excitation, a large volume, multiple-path He-3-Ar nuclear laser has produced an output of 1 kilowatt. Power deposition was shown to be homogeneous over this volume. The CO laser has been pumped for the first time using the He-3 reaction, producing approximately 200 Watts. Using a boron-10 coating to excite N2, nuclear lasing has been achieved in CO2 in a transfer laser configuration. Nuclear lasing of Ar-Xe has been demonstrated using fission fragment excitation from U-235F6. Research on the gas core reactor has resulted in a steady state operational power of 30 kilowatts with flowing U-235F6 in an argon vortex.

  12. Wavelength diversity in optically pumped alkali vapor lasers (United States)

    Perram, Glen P.


    Alternative wavelengths for optically pumped alkali vapor lasers have been developed using single photon excitation of higher lying P-states, stimulated Raman processes, two-photon excitation of S and D states, and electric quadruple excitation on S-D transitions. Two photon excitation of Cs 72D leads to competing and cascade lasing producing red and infrared lasers operating on the D-P transitions, followed by ultraviolet, blue, the standard near infrared DPAL transitions operating on P-S transitions. The S-D pump transitions are fully bleached at pump intensities exceeding 1 MW/cm2, allowing for lasing transitions that terminate on the ground state. The kinetics of these systems are complex due to competition for population inversion among the many optical transitions. An optically pumped mid-infrared rubidium pulsed, mirrorless laser has also been demonstrated in a heat pipe along both the 62P3/2 - 62S1/2 transition at 2.73 μm and the 62P1/2 - 62S1/2 transition at 2.79 μm with a maximum energy of 100 nJ. Performance improves dramatically as the rubidium vapor density is increased, in direct contradiction with the prior work. No scaling limitations associated with energy pooling or ionization kinetics have been observed. Practical application for infrared counter measures depends on the further development of blue diode pump sources. Finally, stimulated electronic Raman scattering and hyper-Raman processes in potassium vapor near the D1 and D2 lines have been observed using a stable resonator and pulsed laser excitation. First and second order Stokes and anti-Stokes lines were observed simultaneously and independently for a pump laser tuning range exceeding 70 cm-1. When the pump is tuned between the K D1 and D2 lines, an efficient hyper-Raman process dominates with a slope efficiency that exceeds 10%. Raman shifted laser may be useful as a target illuminator or atmospheric compensation beacon for a high power diode pumped alkali laser.

  13. 3He melting pressure temperature scale

    DEFF Research Database (Denmark)

    Halperin, W.P.; Archie, C.N.; Richardson, R.C.;


    The latent heat for solidification of **3He has been measured along the **3He melting curve between 23 and 1 mK. A temperature scale is established which depends only on measurements of heat, pressure and volume, and on the condition that the entropy of solid **3He approaches R ln 2 at high...... temperatures. The A feature of the melting curve which suggests itself as a thermometric fixed point is found to be T//A equals 2. 75 plus or minus 0. 11 mK. The agreement between this value and independent measurements of T//A, based on nuclear or electronic paramagnetism, Johnson noise thermometry...

  14. Cladding for transverse-pumped solid-state laser (United States)

    Byer, Robert L. (Inventor); Fan, Tso Y. (Inventor)


    In a transverse pumped, solid state laser, a nonabsorptive cladding surrounds a gain medium. A single tranverse mode, namely the Transverse Electromagnetic (TEM) sub 00 mode, is provided. The TEM sub 00 model has a cross sectional diameter greater than a transverse dimension of the gain medium but less than a transverse dimension of the cladding. The required size of the gain medium is minimized while a threshold for laser output is lowered.

  15. Development of a thermodynamic model for a cold cycle 3He-4He dilution refrigerator (United States)

    Mueller, B. W.; Miller, F. K.


    A thermodynamic model of a 3He-4He cold cycle dilution refrigerator with no actively-driven mechanical components is developed and investigated. The refrigerator employs a reversible superfluid magnetic pump, passive check valves, a phase separation chamber, and a series of recuperative heat exchangers to continuously circulate 3He-4He and maintain a 3He concentration gradient across the mixing chamber. The model predicts cooling power and mixing chamber temperature for a range of design and operating parameters, allowing an evaluation of feasibility for potential 3He-4He cold cycle dilution refrigerator prototype designs. Model simulations for a prototype refrigerator design are presented.

  16. High-power diode-pumped Tm:YLF slab laser

    CSIR Research Space (South Africa)

    Schellhorn, M


    Full Text Available The aim is to develop a high-power Tm:YLF slab laser which can be utilized to pump a Ho slab laser. A 68 W Tm:YLF slab laser was recently presented in [1] pumped from one end by a single 6-bar stack delivering ~300 W of pump power. In this work, we...

  17. Turning a random laser into a tunable singlemode laser by active pump shaping

    CERN Document Server

    Bachelard, N; Noblin, X; Sebbah, P


    A laser is not necessarily a sophisticated device: Pumping energy into an amplifying medium randomly filled with scatterers, a powder for instance, makes a perfect "random laser." In such a laser, the absence of mirrors greatly simplifies laser design, but control over emission directionality or frequency tunability is lost, seriously hindering prospects for this otherwise simple laser. We recently proposed a novel approach to harness random lasers, inspired by spatial shaping methods recently employed for coherent light control in complex media. Here, we experimentally implement this method in an optofluidic random laser where modes are spatially extended and therefore strongly overlap, making individual selection a priori impossible. We show that control over the random laser emission can indeed be regained by actively shaping the spatial profile of the optical pump. This unique degree of freedom, which has never been really exploited, allows us to select any desired wavelength and shaping of lasing modes, ...

  18. Efficient Ho:YLF laser pumped by a Tm:fiber laser

    CSIR Research Space (South Africa)

    Koen, W


    Full Text Available Laser sources emitting in the 2 micron region is of particular interest for applications in medicine, remote sensing (LIDAR) and directed infra-red countermeasures. In addition, they are also desirable pump sources for efficient optical parametric...

  19. Continuously tunable solution-processed organic semiconductor DFB lasers pumped by laser diode. (United States)

    Klinkhammer, Sönke; Liu, Xin; Huska, Klaus; Shen, Yuxin; Vanderheiden, Sylvia; Valouch, Sebastian; Vannahme, Christoph; Bräse, Stefan; Mappes, Timo; Lemmer, Uli


    The fabrication and characterization of continuously tunable, solution-processed distributed feedback (DFB) lasers in the visible regime is reported. Continuous thin film thickness gradients were achieved by means of horizontal dipping of several conjugated polymer and blended small molecule solutions on cm-scale surface gratings of different periods. We report optically pumped continuously tunable laser emission of 13 nm in the blue, 16 nm in the green and 19 nm in the red spectral region on a single chip respectively. Tuning behavior can be described with the Bragg-equation and the measured thickness profile. The laser threshold is low enough that inexpensive laser diodes can be used as pump sources.

  20. A High-Pressure Polarized $^3$He Gas Target for Nuclear Physics Experiments Using A Polarized Photon Beam

    CERN Document Server

    Ye, Q; Chen, W; Gao, H; Zheng, W; Zong, X; Averett, T; Cates, G D; Tobias, W A


    Following the first experiment on three-body photodisintegration of polarized $^3$He utilizing circularly polarized photons from High Intensity Gamma Source (HI$\\gamma$S) at Duke Free Electron Laser Laboratory (DFELL), a new high-pressure polarized $^3$He target cell made of pyrex glass coated with a thin layer of sol-gel doped with aluminum nitrate nonahydrate has been built in order to reduce photon beam induced backgrounds. The target is based on the technique of spin-exchange optical pumping of hybrid rubidium and potassium and the highest polarization achieved is $\\sim$62\\% determined from both NMR-AFP and EPR polarimetry. The $X$ parameter is estimated to be $0.17\\pm0.06$ and the performance of the target is in good agreement with theoretical predictions. We also present beam test results from this new target cell and the comparison with the GE180 $^3$He target cell used previously at HI$\\gamma$S. This is the first time that sol-gel coating technique has been used in a polarized $^3$He target for nuclea...

  1. Neodymium YAG lasers pumped by light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Bilak, V.I.; Goldobin, I.S.; Zverev, G.M.; Kuratev, I.I.; Pashkov, V.A.; Stel' makh, M.F.; Tsvetkov, Y.V.; Solov' eva, N.M.


    The results are presented of theoretical and experimental investigations of room-temperature YAG:Nd lasers pumped by light-emitting diodes. The lasing characteristics of a laser operated at the 1.06 and 1.32 wavelengths were investigated in the cw and pulsed regimes and dependences of its parameters on the temperature, pulse repetition frequency, and other factors were studied. In the pulsed regime the laser efficiency was 0.2% and in the cw regime the radiation power reached 50 and 17 mW at the 1.06 and 1.32 wavelengths, respectively.

  2. Ho:KLuW microchip laser intracavity pumped by a diode-pumped Tm:KLuW laser (United States)

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


    A compact intracavity-pumped microchip Ho laser is realized using stacked Tm:KLuW/Ho:KLuW crystals pumped by a laser diode at 805 nm; both crystals are cut for light propagation along the N g optical indicatrix axis and emit with polarization along the N m axis. Maximum CW output power of 285 mW is achieved at a wavelength of 2080 nm for 5.6 W absorbed pump power in the Tm:KLuW crystal with a maximum slope efficiency of 8.3 %. Maximum total (Tm3+ and Ho3+ emission) output of 887 mW with a slope efficiency of 23 % is achieved. Laser operation is obtained in the 1867-1900 nm spectral range corresponding to the Tm emission, while Ho emits at 2078-2100 nm, depending on the output coupling. The microchip Ho laser generates a near-circular output beam with M 2 < 1.1. The compact laser setup with plane-plane cavity provides automatic mode-matching condition for the Tm and Ho laser modes.

  3. Magnetic composite Hydrodynamic Pump with Laser Induced Graphene Electrodes

    KAUST Repository

    Khan, Mohammed Asadullah


    A polymer based magneto hydrodynamic pump capable of actuating saline fluids is presented. The benefit of this pumping concept to operate without any moving parts is combined with simple and cheap fabrication methods and a magnetic composite material, enabling a high level of integration. The operating principle, fabrication methodology and flow characteristics of the pump are detailed. The pump electrodes are created by laser printing of polyimide, while the permanent magnet is molded from an NdFeB powder - polydimethylsiloxane (PDMS) composite. The cross-section area of the pump is 240 mm $^2$ . The electrode length is 5 mm. The magnetic characteristics of the NdFeB-PDMS composite indicate high degree of magnetization, which increases the pump efficiency. Using a saline solution similar to seawater, the pump produces 3.4 mm/s flow velocity at a voltage of 7.5V and a current density of 30 mA/cm $^2$ .

  4. Influence of light polarization on the dynamics of optically pumped lasers

    Energy Technology Data Exchange (ETDEWEB)

    Arjona, M.; Corbalan, R. (Departament de Fisica, Universitat Autonoma de Barcelona, 08193 Bellaterra (Spain)); Laguarta, F.; Pujol, J. (Departament d' Optica i Optometria, Universitat Politecnica de Catalunya, 08222 Terrassa (Spain)); Vilaseca, R. (Departament I. D' Optica, Universitat de Valencia, 46100 Burjassot (Spain))


    The dynamic behavior of a coherently pumped ring laser with a homogeneously broadened four-level medium is analyzed theoretically, considering linearly polarized pump and generated laser beams. The laser is shown to be much more stable when these polarizations are parallel than when they are orthogonal. In the latter case the instability pump threshold can be as low as four times the first laser threshold, and the laser dynamics shows Lorenz-type features.

  5. Experimental study of the diode pumped alkali laser (DPAL) (United States)

    Endo, Masamori; Nagaoka, Ryuji; Nagaoka, Hiroki; Nagai, Toru; Wani, Fumio


    A small-scale cesium diode-pumped alkali laser (DPAL) apparatus has been developed for fundamental researches. A commercial laser diode with volume Bragg grating outcoupler is used to pump the gain cell longitudinally. Both windows of the gain cell are set at Brewster's angle for minimum loss and maximum durability. Output coupling coefficient is continuously variable from 13% to 85% by the slanted quartz plate outcoupler inserted in the optical resonator. Small signal gain is measured with a laser diode probe at various gain cell temperatures. A 6.5 W continuouswave output with 56% optical-to-optical conversion efficiency (based on the absorbed power) has been achieved. A numerical simulation code is developed and its calculation results are in good agreement with the experiments.

  6. High Efficient Continuous-Wave Ho: YAG Laser Pumped by a Diode-pumped Tm: YLF Laser at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    DUAN Xiao-Ming; YAO Bao-Quan; ZHANG Yun-Jun; SONG Cheng-Wei; GAO Jing; JU You-Lun; WANG Yue-Zhu


    We present a high efficient continuous wave Ho:YAG laser pumped by a diode-pumped Tm:YLF laser with a Fabry-Perot etalon tuning at 1.91 μm. The maximum output power reaches 7.2 W when the absorbed pump power is 10.8 W.The slope efficiency (relative to the absorbed power) is 74.1%,and the Tm:YLF to Ho:YAG optical conversion efficiency of 60%,then the diode-to-Holmium optical conversion efficiency achieved is 21.0%.The wavelength is 2090 nm when the transmission of output coupler is larger than 20%.The beam quality factor is M2 ~ 1.15 measured by the travelling knife-edge method.

  7. Diode pumped erbium cascade fiber lasers

    NARCIS (Netherlands)

    Jackson, Stuart D.; Pollnau, Markus; Li, Jianfeng

    Cascading the 4I11/2 -> 4I13/2 transition at 2.8 μm and 4I13/2 -> 4I15/2 transition at 1.6 μm offers a solution to the thermal management of high power Er3+-doped fluoride fiber lasers. We demonstrate an output power of 8.2 W at 2.8 μm from an Er3+-doped fluorozirconate fiber laser with 56 W of

  8. Fibre-coupled red diode-pumped Alexandrite TEM00 laser with single and double-pass end-pumping (United States)

    Arbabzadah, E. A.; Damzen, M. J.


    We report the investigation of an Alexandrite laser end-pumped by a fibre-coupled red diode laser module. Power, efficiency, spatial, spectral, and wavelength tuning performance are studied as a function of pump and laser cavity parameters. It is the first demonstration, to our knowledge, of greater than 1 W power and also highest laser slope efficiency (44.2%) in a diode-pumped Alexandrite laser with diffraction-limited TEM00 mode operation. Spatial quality was excellent with beam propagation parameter M 2 ~ 1.05. Wavelength tuning from 737-796 nm was demonstrated using an intracavity birefringent tuning filter. Using a novel double pass end-pumping scheme to get efficient absorption of both polarisation states of the scrambled fibre-delivered diode pump, a total output coupled power of 1.66 W is produced in TEM00 mode with 40% slope efficiency.

  9. Expansion cooled CO nuclear pumped laser (United States)

    Davis, J. F.; Bird, P. F.; Mansfield, C. R.; Helmick, H. H.


    The paper describes a series of experiments designed to investigate the performance of a fission fragment excited CO laser with gasdynamic cooling. The experiments use a wall source of fission fragments to provide excitation of CO or CO gas mixtures. A separate investigation examines the effects on vibrational excitation distribution of CO or CO gas mixtures with the addition of UF6.

  10. Cosmogenic 3He in detrital gold (United States)

    Stuart, Finlay; Yakubovich, Olga; Caracedo, Ana; Nesterenok, Alexander


    Since the measurement of cosmogenic He in an alluvial diamond by McConville and Reynolds (1996) the application of cosmogenic noble gases to individual detrital grains to quantify surface processes has not been vigorously pursued. The likely low rate of diffusion of cosmogenic He in native metals, and their resistance to weathering and disintegration during erosion and transport, makes them a potential record of long-term Earth surface processes. In an effort to assess the extent that detrital refractory metals record the exposure history during transport and storage we have undertaken a reconnaissance study of the He isotope composition in 18 grains (2-200 mg) of native gold, copper, silver, and PtPd, Pt3Fe and OsIr alloys from alluvial placer deposits from around the world. 4He is dominantly the result of U and Th decay within the grains, or decay of 190Pt in the Pt-rich alloys. 3He is measurable in 13 grains, concentrations range up to 2.7E+6 atoms/g. 3He/4He are always in excess of the crustal radiogenic ratio, up to 306 Ra. Although nucleogenic 3He produced by (n,α) reactions on 6Li, and 3He from trapped hydrothermal fluids, are present, the majority of the 3He is cosmogenic in origin. Using newly calculated cosmogenic 3He production rates in heavy metals, and a determination of the effect of implantation based on the stopping distances of spallogenic 3He and 3H, the grains have 3Hecos concentrations that are equivalent to 0.35 to 1.5 Ma exposure at Earth's surface. In a study of detrital gold grains from several sites in Scotland we have found that 10 % have 3He concentrations that are significantly in excess of that generated since the Last Glacial Maximum. These studies demonstrate that, with refinement, cosmogenic 3He in refractory detrital minerals can be used to quantify sediment transport and storage on the 1-10 Ma timescale. P. McConville & J.H. Reynolds (1989). Geochim. Cosmochim. Acta, 53, 2365-75.

  11. 946 nm Diode Pumped Laser Produces 100mJ (United States)

    Axenson, Theresa J.; Barnes, Norman P.; Reichle, Donald J., Jr.


    An innovative approach to obtaining high energy at 946 nm has yielded 101 mJ of laser energy with an optical-to-optical slope efficiency of 24.5%. A single gain module resonator was evaluated, yielding a maximum output energy of 50 mJ. In order to obtain higher energy a second gain module was incorporated into the resonator. This innovative approach produced un-surprised output energy of 101 mJ. This is of utmost importance since it demonstrates that the laser output energy scales directly with the number of gain modules. Therefore, higher energies can be realized by simply increasing the number of gain modules within the laser oscillator. The laser resonator incorporates two gain modules into a folded "M-shaped" resonator, allowing a quadruple pass gain within each rod. Each of these modules consists of a diode (stack of 30 microlensed 100 Watt diode array bars, each with its own fiber lens) end-pumping a Nd:YAG laser rod. The diode output is collected by a lens duct, which focuses the energy into a 2 mm diameter flat to flat octagonal pump area of the laser crystal. Special coatings have been developed to mitigate energy storage problems, including parasitic lasing and amplified spontaneous emission (ASE), and encourage the resonator to operate at the lower gain transition at 946 nm.

  12. Future directions in 980-nm pump lasers: submarine deployment to low-cost watt-class terrestrial pumps (United States)

    Gulgazov, Vadim N.; Jackson, Gordon S.; Lascola, Kevin M.; Major, Jo S.; Parke, Ross; Richard, Tim; Rossin, Victor V.; Zhang, Kai


    The demands of global bandwidth and distribution are rising rapidly as Internet usage grows. This fundamentally means that more photons are flowing within optical cables. While transmitting sources launches some optical power, the majority of the optical power that is present within modern telecommunication systems originates from optical amplifiers. In addition, modern optical amplifiers offer flat optical gain over broad wavelength bands, thus making possible dense wavelength de-multiplexing (DWDM) systems. Optical amplifier performance, and by extension the performance of the laser pumps that drive them, is central to the future growth of both optical transmission and distribution systems. Erbium-doped amplifiers currently dominate optical amplifier usage. These amplifiers absorb pump light at 980 nm and/or 1480 nm, and achieve gain at wavelengths around 1550 nm. 980 nm pumps achieve better noise figures and are therefore used for the amplification of small signals. Due to the quantum defect, 1480 nm lasers deliver more signal photon per incident photon. In addition, 1480 nm lasers are less expensive than 980 nm lasers. Thus, 1480 nm pump lasers are used for amplification in situations where noise is not critical. The combination of these traits leads to the situation where many amplifiers contain 980 nm lasers to pump the input section of the Er- doped fiber with 1480 nm lasers being used to pump the latter section of Er fiber. This can be thought of as using 980 nm lasers to power an optical pre-amplifier with the power amplification function being pump with 1480 nm radiation. This paper will focus on 980 nm pump lasers and the impact that advances in 980 nm pump technology will have on optical amplification systems. Currently, 980 nm technology is rapidly advancing in two areas, power and reliability. Improving reliability is becoming increasingly important as amplifiers move towards employing more pump lasers and using these pump lasers without redundancy

  13. Resonantly pumped room temperature Ho:LuVO₄ laser. (United States)

    Yao, B Q; Cui, Z; Duan, X M; Du, Y Q; Han, L; Shen, Y J


    Spectroscopic characterization of a Ho:LuVO4 crystal grown by the Czochralski method has been performed, including the absorption and emission spectra. We demonstrate a 2 μm room temperature Ho:LuVO4 laser, resonantly pumped by a 1.94 μm Tm:YAP laser. By use of an output coupler with T=10% transmission, the Ho:LuVO4 laser generated continuous-wave output power of 2.5 W at 2074.18 nm, with a beam quality factor of Mx2=My2=1.3, for a total incident pump power of 19.4 W. The slope efficiency with respect to the pump power was 17.6%, and the optical-to-optical efficiency was 12.9%. Moreover, we obtained a Ho:LuVO4 laser that operated at 2073.77 and 2055.27 nm, by using different output couplers with transmissions of T=15 and 30%.

  14. Generation of Intense THz Pulsed Lasers Pumped Strongly by CO2 Pulsed Lasers

    Institute of Scientific and Technical Information of China (English)

    QI Chun-Chao; CHENG Zu-Hai


    A theoretical method dealing with two intense laser fields interacting with a three-level molecular system is proposed.A discussion is presented on the properties of the solutions for time-independent and time-dependent absorption coefficients and gain coemcient on resonance for strong laser fields,based on analytic evaluation of the rate equations for a homogeneously broadened,three-level molecular system.The pump intensity range can be estimated according to the analytic expression of pump saturation intensity.The effects of pulse width,gas pressure and path length on the energy absorbed from pump light are studied theoretically.The results can be applied to the analysis of pulsed,optically pumped terahertz lasers.

  15. Photoproduction of eta-mesic 3He

    CERN Document Server

    Pfeiffer, M; Annand, J R M; Beck, R; Caselotti, G; Cherepnya, S N; Föhl, K; Fog, L S; Hornidge, D; Janssen, S; Kashevarov, V; Kondratiev, R; Kotulla, M; Krusche, B; McGeorge, J C; MacGregor, I J D; Mengel, K; Messchendorp, J G; Metag, V; Novotny, R; Rost, M; Sack, S; Sanderson, R; Schadmand, S; Thomas, A; Watts, D P


    The photoproduction of eta-mesic 3He has been investigated using the TAPS calorimeter at the Mainz Microtron accelerator facility MAMI. The total inclusive cross section for the reaction gamma+3He->eta+X has been measured for photon energies from threshold to 820 MeV. The total and angular differential coherent eta cross sections have been extracted up to energies of 745 MeV. A resonance-like structure just above the eta production threshold with an isotropic angular distribution suggests the existence of a resonant quasi-bound state. This is supported by studies of a competing decay channel of such a quasi-bound eta-mesic nucleus into pi^0+p+X. A binding energy of (4+-4) MeV and a width of (25+-6) MeV is deduced for the quasi-bound eta-mesic state in 3He.

  16. Photoproduction of eta-mesic 3He. (United States)

    Pfeiffer, M; Ahrens, J; Annand, J R M; Beck, R; Caselotti, G; Cherepnya, S; Föhl, K; Fog, L S; Hornidge, D; Janssen, S; Kashevarov, V; Kondratiev, R; Kotulla, M; Krusche, B; McGeorge, J C; MacGregor, I J D; Mengel, K; Messchendorp, J G; Metag, V; Novotny, R; Rost, M; Sack, S; Sanderson, R; Schadmand, S; Thomas, A; Watts, D P


    The photoproduction of eta-mesic 3He has been investigated using the TAPS calorimeter at the Mainz Microtron accelerator facility MAMI. The total inclusive cross section for the reaction gamma3He-->etaX has been measured for photon energies from threshold to 820 MeV. The total and angular differential coherent eta cross sections have been extracted up to energies of 745 MeV. A resonancelike structure just above the eta production threshold with an isotropic angular distribution suggests the existence of a resonant quasibound state. This is supported by studies of a competing decay channel of such a quasibound eta-mesic nucleus into pi(0)pX. A binding energy of (-4.4+/-4.2) MeV and a width of (25.6+/-6.1) MeV is deduced for the quasibound eta-mesic state in 3He.

  17. Coherent Photoproduction of pi^+ from 3/^He

    Energy Technology Data Exchange (ETDEWEB)

    Rakhsha Nasseripour, Barry Berman


    We have measured the differential cross section for the $\\gamma$$^3$He$\\rightarrow \\pi^+ t$ reaction. This reaction was studied using the CEBAF Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid $^3$He target. The differential cross sections for the $\\gamma$$^3$He$\\rightarrow \\pi^+ t$ reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at backward angles, showing that additional components must be added to the model.

  18. Electric-discharge-pumped nitrogen ion laser (United States)

    Laudenslager, J. B.; Pacala, T. J.; Wittig, C.


    The routine operation is described of an N2(+) laser oscillating on the first negative band system of N2(+) which is produced in a preionized transverse discharge device. The discharge design incorporates features which favor the efficient production of the excitation transfer reaction of He2(+) with N2. A capacitive discharge switched by means of a high-current grounded grid thyratron is used to meet the design requirement of a volumetric discharge in high-pressure gas mixtures where the electric discharge need not have an ultrafast rise time (greater than 10 nsec) but should be capable of transferring large quantities of stored electric energy to the gas. A peak power of 180 kW in an 8-nsec laser pulse was obtained with a 0.1% mixture of N2 in helium at a total pressure of 3 atm. The most intense laser oscillations were observed on the (0,1) vibrational transition at 427.8 microns.

  19. Optimized high-power diode laser, laser arrays, and bars for pump applications (United States)

    Hülsewede, R.; Schulze, H.; Sebastian, J.; Schröder, D.; Meusel, J.; Wolf, J.; Hennig, P.


    Broad area diode laser and diode laser bars are the most efficient light sources. In comparison to solid state laser or gas laser systems the over all beam quality of the diode laser is poor. Thus most application of diode laser bars is high efficient pumping of solid state lasers converting the beam quality and scaling the power of laser systems within the kW range. The pump efficiency and the beam coupling efficiency of the diode laser pumped systems has to be increased to meet the increasing laser market demands for reduced costs. JENOPTIK Diode Lab GmbH (JDL) has optimized their high power brilliance bars to enable reliable high power operation especially, for the 9xx nm wavelength range and low far field divergences. Superior reliability with long operation time of 13,000 hours and high power operation of 200 W are demonstrated for high power bars high filling factor mounted on passively cooled heat sinks. Smaller far field divergence at high power levels requires longer cavity length and higher efficiencies in the beam coupling needs requires lower filling factors. The new high brilliance bars and arrays with 20% filling factor are showing high power operation up to 95 W and a slow axis beam divergence of less than 8° (95% power content).

  20. Efficient laser-diode end-pumped Nd:GGG lasers at 1054 and 1067 nm. (United States)

    Xu, Bin; Xu, Huiying; Cai, Zhiping; Camy, P; Doualan, J L; Moncorgé, R


    Efficient and compact laser-diode end-pumped Nd:GGG simultaneous multiwavelength continuous-wave lasers at ∼1059, ∼1060 and ∼1062  nm were first demonstrated in a free-running 30 mm plano-concave laser cavity. The maximum output power was up to 3.92 W with a slope efficiency of about 53.6% with respect to the absorbed pump power. By inserting a 0.1 mm optical glass plate acting as a Fabry-Pérot etalon, a single-wavelength laser at ∼1067  nm with a maximum output power of 1.95 W and a slope efficiency of 28.5% can be obtained. Multiwavelength lasers, including those at ∼1054 or ∼1067  nm, were also achievable by suitably tilting the glass etalon. These simultaneous multiwavelength lasers provide a potential source for terahertz wave generation.

  1. High power pump laser diodes for 2μm fibre laser (United States)

    Pawlik, S.; Todt, R.; Moser, M.; Romero, O.; Lichtenstein, N.


    We report on our recent developments at II-VI Laser Enterprise of laser diode sources for the 79x nm range. High power conversion efficiency in excess of 62% was demonstrated. For high power applications like Thulium fiber laser pumping we have achieved an output power of more than 12.5W in CW operation for 94 μm wide broad-area single-emitters. We added the functionality of wavelength stabilization to the laser diodes by using a distributed feedback grating (DFB). Locking has been obtained over the full current range between 1A and 4A tested so far with some margin for temperature variation. For efficient fiber laser pumping the laser diodes were integrated in a multi-emitter platform, achieving 38 W out of a 105 μm fiber within 0.15 NA.

  2. High-Reliability Pump Module for Non-Planar Ring Oscillator Laser (United States)

    Liu, Duncan T.; Qiu, Yueming; Wilson, Daniel W.; Dubovitsky, Serge; Forouhar, Siamak


    We propose and have demonstrated a prototype high-reliability pump module for pumping a Non-Planar Ring Oscillator (NPRO) laser suitable for space missions. The pump module consists of multiple fiber-coupled single-mode laser diodes and a fiber array micro-lens array based fiber combiner. The reported Single-Mode laser diode combiner laser pump module (LPM) provides a higher normalized brightness at the combined beam than multimode laser diode based LPMs. A higher brightness from the pump source is essential for efficient NPRO laser pumping and leads to higher reliability because higher efficiency requires a lower operating power for the laser diodes, which in turn increases the reliability and lifetime of the laser diodes. Single-mode laser diodes with Fiber Bragg Grating (FBG) stabilized wavelength permit the pump module to be operated without a thermal electric cooler (TEC) and this further improves the overall reliability of the pump module. The single-mode laser diode LPM is scalable in terms of the number of pump diodes and is capable of combining hundreds of fiber-coupled laser diodes. In the proof-of-concept demonstration, an e-beam written diffractive micro lens array, a custom fiber array, commercial 808nm single mode laser diodes, and a custom NPRO laser head are used. The reliability of the proposed LPM is discussed.

  3. Enhancement of pump efficiency of thin disk lasers by compensation of directional image extension on pumping spot (United States)

    Zamani, Sasan Seyed; Eslami, Esmaeil


    The effect of directional image extension on the total pumping spot in thin disk lasers is reviewed. Three modified pumping setups that can compensate this effect and improve the absorption pumping area are presented, and the efficiency, advantages, and disadvantages of each modified configuration are discussed. Numerical comparison between absorption intensity profiles confirms an increment of maximum pump absorption density at the central region of the pumping area with respect to normal setup. Experimental investigation for the last modified pumping arrangement is in good agreement with simulation results. Measuring laser power output with a similar simple I-shaped resonator shows an enhancement of slope efficiency up to 2.5% together with a lower laser threshold for our modified setup.

  4. Narrow line diode laser stacks for DPAL pumping (United States)

    Koenning, Tobias; Irwin, David; Stapleton, Dean; Pandey, Rajiv; Guiney, Tina; Patterson, Steve


    Diode pumped alkali metal vapor lasers (DPALs) offer the promise of scalability to very high average power levels while maintaining excellent beam quality, making them an attractive candidate for future defense applications. A variety of gain media are used and each requires a different pump wavelength: near 852nm for cesium, 780nm for rubidium, 766nm for potassium, and 670nm for lithium atoms. The biggest challenge in pumping these materials efficiently is the narrow gain media absorption band of approximately 0.01nm. Typical high power diode lasers achieve spectral widths around 3nm (FWHM) in the near infrared spectrum. With state of the art locking techniques, either internal to the cavity or externally mounted gratings, the spectral width can typically be reduced to 0.5nm to 1nm for kW-class, high power stacks. More narrow spectral width has been achieved at lower power levels. The diode's inherent wavelength drift over operating temperature and output power is largely, but not completely, eliminated. However, standard locking techniques cannot achieve the required accuracy on the location of the spectral output or the spectral width for efficient DPAL pumping. Actively cooled diode laser stacks with continuous wave output power of up to 100W per 10mm bar at 780nm optimized for rubidium pumping will be presented. Custom designed external volume holographic gratings (VHGs) in conjunction with optimized chip material are used to narrow and stabilize the optical spectrum. Temperature tuning on a per-bar-level is used to overlap up to fifteen individual bar spectra into one narrow peak. At the same time, this tuning capability can be used to adjust the pump wavelength to match the absorption band of the active medium. A spectral width of <0.1nm for the entire stack is achieved at <1kW optical output power. Tuning of the peak wavelength is demonstrated for up to 0.15nm. The technology can easily be adapted to other diode laser wavelengths to pump different materials.

  5. Two-photon pumped lead halide perovskite nanowire lasers

    CERN Document Server

    Gu, Zhiyuan; Sun, Wenzhao; Li, Jinakai; Liu, Shuai; Song, Qinghai; Xiao, Shumin


    Solution-processed lead halide perovskites have shown very bright future in both solar cells and microlasers. Very recently, the nonlinearity of perovskites started to attract considerable research attention. Second harmonic generation and two-photon absorption have been successfully demonstrated. However, the nonlinearity based perovskite devices such as micro- & nano- lasers are still absent. Here we demonstrate the two-photon pumped nanolasers from perovskite nanowires. The CH3NH3PbBr3 perovskite nanowires were synthesized with one-step solution self-assembly method and dispersed on glass substrate. Under the optical excitation at 800 nm, two-photon pumped lasing actions with periodic peaks have been successfully observed at around 546 nm. The obtained quality (Q) factors of two-photon pumped nanolasers are around 960, and the corresponding thresholds are about 674?J=cm2. Both the Q factors and thresholds are comparable to conventional whispering gallery modes in two-dimensional polygon microplates. Ou...

  6. Continuous variable entanglement in a coherently pumped correlated emission laser

    Energy Technology Data Exchange (ETDEWEB)

    Tesfa, Sintayehu [Physics Department, Addis Ababa University, PO Box 1176, Addis Ababa (Ethiopia)], E-mail:


    Analysis of the effects of external pumping on the quantum features of cavity radiation of the two-photon correlated emission laser is presented. It turns out that the pumping process induces the atomic coherence responsible for the entanglement of the cavity radiation as well as the correlation between the photon numbers belonging to different modes, despite the arising vacuum fluctuations. The photon number correlation is found to be very close to 2 where the entanglement is relatively better. Moreover, the mean number of photon pairs decreases with the amplitude of the driving radiation which is one of the practical limitations associated with the pumping mechanism. It is also shown that the mean photon number of the radiation in mode b is less than one-third of that in mode a.

  7. High repetition rate femtosecond dye amplifier using a laser diode pumped neodymium:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Zysset, B.; LaGasse, M.J.; Fujimoto, J.G.; Kafka, J.D.


    A high repetition rate femtosecond dye amplifier is demonstrated using a laser diode pumped Q-switched Nd:YAG laser. Amplification of wavelength tunable 300 fs pulses from a synchronously mode-locked rhodamine dye laser is achieved with a saturated gain of 70 and a small gain of 200 at a repetition rate of 800 Hz. Maximum pulse energies of 40 nJ are obtained, and pulse compression to as short as 30 fs is demonstrated.

  8. High repetition rate femtosecond dye amplifier using a laser diode pumped neodymium:YAG laser (United States)

    Zysset, B.; LaGasse, M. J.; Fujimoto, J. G.; Kafka, J. D.


    A high repetition rate femtosecond dye amplifier is demonstrated using a laser diode pumped Q-switched Nd:YAG laser. Amplification of wavelength tunable 300 fs pulses from a synchronously mode-locked rhodamine dye laser is achieved with a saturated gain of 70 and a small gain of 200 at a repetition rate of 800 Hz. Maximum pulse energies of 40 nJ are obtained, and pulse compression to as short as 30 fs is demonstrated.

  9. Quasi-CW Diode Laser End-pumped Yb3+∶GlassMicrochip Laser

    Institute of Scientific and Technical Information of China (English)

    DAI Shixun; HU Lili; LIU Zhuping; HUANG Guosong; JIANG Zhonghong; YASUKAZU Izawa


    Quasi-CW diode-pumped Yb3+∶borate glass and Yb3+∶phosphate glass microchip lasers have been reported. From Yb3+∶phosphate glass laser, the maximum average output power was 31 mW and the optical-optical conversion efficiency was 5%.The maximum average output power was 18 mW, and optical-optical conversion efficiency was 3% for Yb3+∶borate glass laser.

  10. Collective excitations of sup 3 He clusters

    Energy Technology Data Exchange (ETDEWEB)

    Serra, Ll.; Garcias, F. (Universidad de las Islas Baleares, Palma de Mallorca (Spain). Dept. de Fisica); Barranco, M. (Barcelona Univ. (Spain). Dept. de Estructura y Constituyentes de la Materia); Navarro, J. (Valencia Univ. (Spain). Dept. de Fisica Atomica, Molecular y Nuclear Consejo Superior de Investigaciones Cientificas, Valencia (Spain). Inst. de Fisica Corpuscular); Giai, V. (Paris-11 Univ., 91 - Orsay (France). Div. de Physique Theorique)


    Collective excitations of {sup 3}He clusters are studied by treating the cluster as a quantum liquid drop. We have used the Random-Phase Approximation sum rules technique within a Density Functional Formalism. Results for L=2 to 10 surface modes and the L=0 volume mode are presented. (orig.).

  11. Diode-pumped Yb3+:KYF4 femtosecond laser. (United States)

    Coluccelli, Nicola; Galzerano, Gianluca; Tonelli, Mauro; Laporta, Paolo; Svelto, Orazio


    Passive mode locking of a diode-pumped Yb(3+):KYF(4) laser is demonstrated using a semiconductor saturable absorber mirror. A high-stability, transform-limited pulse train with a repetition rate of 57 MHz is generated. Solitonlike pulses with maximum average output power of 250 mW, minimum pulse duration of 170 fs, and rms time jitter of 360 fs were obtained.

  12. Thin-Film Evaporative Cooling for Side-Pumped Laser (United States)

    Stewart, Brian K. (Inventor)


    A system and method are provided for cooling a crystal rod of a side-pumped laser. A transparent housing receives the crystal rod therethrough so that an annular gap is defined between the housing and the radial surface of the crystal rod. A fluid coolant is injected into the annular gap such the annular gap is partially filled with the fluid coolant while the radial surface of the crystal rod is wetted as a thin film all along the axial length thereof.

  13. Efficient, resonantly pumped, room-temperature Er3+:GdVO4 laser. (United States)

    Ter-Gabrielyan, N; Fromzel, V; Ryba-Romanowski, W; Lukasiewicz, T; Dubinskii, M


    We report an efficient room-temperature operation of a resonantly pumped Er3+:GdVO4 laser at 1598.5 nm. The maximum continuous wave (CW) output power of 3.5 W with slope efficiency of 56% was achieved with resonant pumping by an Er-fiber laser at 1538.6 nm. With pumping by a commercial laser diode bar stack, a quasi-CW (QCW) output of 7.7 W and maximum slope efficiency of ~53% versus absorbed pump power were obtained. This is believed to be the first resonantly (in-band) pumped, room-temperature Er3+:GdVO4 laser.

  14. Compact KGd(WO4)2 picosecond pulse-train synchronously pumped broadband Raman laser. (United States)

    Gao, Xiao Qiang; Long, Ming Liang; Meng, Chen


    We demonstrate an efficient approach to realizing an extra-cavity, synchronously pumped, stimulated Raman cascaded process under low repetition frequency (1 kHz) pump conditions. We also construct a compact KGd(WO4)2 (KGW) crystal picosecond Raman laser that has been configured as the developed method. A pulse-train green laser pumped the corresponding 70 mm long KGW crystal Raman cavity. The pulse train contains six pulses, about 800 ps separated, for every millisecond; thus, it can realize synchronous pumping between pump pulse and the pumped Raman cavity. The investigated system produced a collinear Raman laser output that includes six laser lines covering the 532 to 800 nm spectra. This is the first report on an all-solid-state, high-average-power picosecond collinear multi-wavelength (more than three laser components) laser to our knowledge. This method has never been reported on before in the synchronously pumped stimulated Raman scattering (SRS) realm.

  15. Method and system for homogenizing diode laser pump arrays

    Energy Technology Data Exchange (ETDEWEB)

    Bayramian, Andrew James


    An optical amplifier system includes a diode pump array including a plurality of semiconductor diode laser bars disposed in an array configuration and characterized by a periodic distance between adjacent semiconductor diode laser bars. The periodic distance is measured in a first direction perpendicular to each of the plurality of semiconductor diode laser bars. The diode pump array provides a pump output propagating along an optical path and characterized by a first intensity profile measured as a function of the first direction and having a variation greater than 10%. The optical amplifier system also includes a diffractive optic disposed along the optical path. The diffractive optic includes a photo-thermo-refractive glass member. The optical amplifier system further includes an amplifier slab having an input face and position along the optical path and separated from the diffractive optic by a predetermined distance. A second intensity profile measured at the input face of the amplifier slab as a function of the first direction has a variation less than 10%.

  16. High-efficiency diode-pumped femtosecond Yb:YAG ceramic laser

    DEFF Research Database (Denmark)

    Zhou, Binbin; Wei, Z.Y.; Zou, Y.W.


    A highly efficient diode-end-pumped femtosecond Yb:yttrium aluminum garnet (YAG) ceramic laser was demonstrated. Pumped by a 968 nm fiber-coupled diode laser, 1.9 W mode-locked output power at a repetition rate of 64.27 MHz was obtained with 3.5 W absorbed pump power, corresponding to a slope...

  17. Photonic crystal fibers for supercontinuum generation pumped by a gain-switched CW fiber laser

    DEFF Research Database (Denmark)

    Larsen, Casper; Noordegraaf, Danny; Hansen, Kim P.


    Supercontinuum generation in photonics crystal fibers (PCFs) pumped by CW lasers yields high spectral power density and average power. However, such systems require very high pump power and long nonlinear fibers. By on/off modulating the pump diodes of the fiber laser, the relaxation oscillations...

  18. Polarized [sup 3]He ion source based on polarized electron capture

    Energy Technology Data Exchange (ETDEWEB)

    Ohshima, Takashi (Osaka Univ., Toyonaka (Japan). Faculty of Science)


    The [sup 3]He[sup +] ions which are formed by [sup 3]He[sup 2+] ions capturing the polarized electrons of the sodium atoms polarized by optical pumping become nuclear polarized beam, as electron polarization shifts to nuclei by ultrafine interaction. When the current of [sup 3]He[sup 2+] ions was 2 e[mu]A, and the degree of polarization of sodium atoms was 0.30[+-]0.05, the [sup 3]He[sup +] beam of nuclear polarization degree 0.0415[+-]0.0061 and beam current 40 nA was obtained. By carrying out the improvement such as the increase of the degree of polarization of sodium or the current of [sup 3]He[sup 2+], it can be expected to form the polarized beam of current more than 10 [mu]A and degree of polarization close to 30%. The polarization experiment carried out so far was mostly on protons and deuterons, and as for [sup 3]He, there was only one polarization experiment. In Research Center for Nuclear Physics, Osaka University, the [sup 3]He beam up to 530 MeV can be obtained by using the ring cyclotron, therefore, it was decided to develop the polarized [sup 3]He ion source using polarized electron capture. The principle of polarization formation, the experimental equipment consisting of ECR ion source, polarized Na target and [sup 3]He nuclear polarization measuring part, and the experimental results are reported. (K.I.).

  19. Laser-diode pumped Nd:GdVO4 ultraviolet laser with LBO frequency tripling

    Institute of Scientific and Technical Information of China (English)

    WANG Yun; FAN Xiu-wei; PENG Qian-qian; LIU Jie; HE Jing-liang


    We have demonstrated a laser-diode pumped Nd:GdVO4 extra-cavity frequency tripling ultraviolet laser with a LBO crystal in this paper.Under the acousto-optic (A-O) Q-switched operation,we have obtained 355 nm ultraviolet laser,with pulse width of 25 ns and pulse repetition rate of 20 kHz.By using a type Ⅰ non-critical phase-matched LBO crystal,the SHG output power of 822 mW is achieved at the incident pump power of 16 W. The output power of 355nm UV laser is 260mW with a type Ⅱ phase-matched LBO crystal,and the conversion efficiency (1 064 nm-355 nm ) is 5.9 %.The power stability of 355 nm laser is 1.7% in 1 h.

  20. Gain dynamics of a free-space nitrogen laser pumped by circularly polarized femtosecond laser pulses

    CERN Document Server

    Yao, Jinping; Zeng, Bin; Chu, Wei; Li, Guihua; Ni, Jielei; Zhang, Haisu; Jing, Chenrui; Zhang, Chaojin; Xu, Huailiang; Cheng, Ya; Xu, Zhizhan


    We experimentally demonstrate ultrafast dynamic of generation of a strong 337-nm nitrogen laser by injecting an external seed pulse into a femtosecond laser filament pumped by a circularly polarized laser pulse. In the pump-probe scheme, it is revealed that the population inversion between the excited and ground states of N2 for the free-space 337-nm laser is firstly built up on the timescale of several picoseconds, followed by a relatively slow decay on the timescale of tens of picoseconds, depending on the nitrogen gas pressure. By measuring the intensities of 337-nm signal from nitrogen gas mixed with different concentrations of oxygen gas, it is also found that oxygen molecules have a significant quenching effect on the nitrogen laser signal. Our experimental observations agree with the picture of electron-impact excitation.

  1. Compact intra-cavity frequency doubled line beam green laser by a laser diode array pumped (United States)

    Yan, Boxia; Qi, Yan; Wang, Yanwei


    Compact, high power, and low-cost green laser light sources are needed in projection-related applications such as digital cinema, rear-projection television, simulators, and command and control stations. We report a LD array directly pumped intracavity SHG Nd:YVO4/PPMgLN laser without lens or waveguide in this letter. A compact 3.12 W green laser was demonstrated by intra-cavity frequency doubled using a PPMgLN bulk crystal by a 19-emitter LD array pumped(single bar), the conversion efficiency from input LD array was 9.2%. A line-beam output suitable for laser projectors was generated, which has the potential to be scalable to small volumes and low costs for laser projection displays.

  2. Designing a Broadband Pump for High-Quality Micro-Lasers via Modified Net Radiation Method (United States)

    Nechayev, Sergey; Reusswig, Philip D.; Baldo, Marc A.; Rotschild, Carmel


    High-quality micro-lasers are key ingredients in non-linear optics, communication, sensing and low-threshold solar-pumped lasers. However, such micro-lasers exhibit negligible absorption of free-space broadband pump light. Recently, this limitation was lifted by cascade energy transfer, in which the absorption and quality factor are modulated with wavelength, enabling non-resonant pumping of high-quality micro-lasers and solar-pumped laser to operate at record low solar concentration. Here, we present a generic theoretical framework for modeling the absorption, emission and energy transfer of incoherent radiation between cascade sensitizer and laser gain media. Our model is based on linear equations of the modified net radiation method and is therefore robust, fast converging and has low complexity. We apply this formalism to compute the optimal parameters of low-threshold solar-pumped lasers. It is revealed that the interplay between the absorption and self-absorption of such lasers defines the optimal pump absorption below the maximal value, which is in contrast to conventional lasers for which full pump absorption is desired. Numerical results are compared to experimental data on a sensitized Nd3+:YAG cavity, and quantitative agreement with theoretical models is found. Our work modularizes the gain and sensitizing components and paves the way for the optimal design of broadband-pumped high-quality micro-lasers and efficient solar-pumped lasers.

  3. Diode-pumped all-solid-state lasers and applications

    CERN Document Server

    Parsons-Karavassilis, D


    This thesis describes research carried out by the within the Physics Department at Imperial College that was aimed at developing novel all-solid-state laser sources and investigating potential applications of this technology. A description of the development, characterisation and application of a microjoule energy level, diode-pumped all-solid-state Cr:LiSGAF femtosecond oscillator and regenerative amplifier system is presented. The femtosecond oscillator was pumped by two commercially available laser diodes and produced an approx 80 MHz pulse train of variable pulse duration with approx 30 mW average output power and a tuning range of over approx 60 nm. This laser oscillator was used to seed a regenerative amplifier, resulting in adjustable repetition rate (single pulse to 20 kHz) approx 1 mu J picosecond pulses. These pulses were compressed to approx 150 fs using a double-pass twin-grating compressor. The amplifier's performance was investigated with respect to two different laser crystals and different pul...

  4. Longitudinal discharge pumped low-pressure XeCl laser (United States)

    Fedorov, A. I.


    We have studied output parameters of a XeCl and a N2 laser pumped by a longitudinal discharge with automatic spark UV preionisation. The output parameters of a low-pressure (30 Torr) XeCl laser operating with Ar, Ne and He as buffer gases or with no buffer gas have been optimised for the first time. The laser generated 5-ns FWHM pulses with an average power of 0.5 mW and output energy of 0.15 mJ. Under longitudinal discharge pumping, an output energy per unit volume of 1.8 J L-1 atm-1 was reached using helium as a buffer gas. With argon-containing and buffer-free mixtures, it was 1.5 J L-1 atm-1. The N2 laser generated 2.5-ns FWHM pulses with an average power of 0.35 mW and output energy of 0.05 mJ.

  5. Ultrafast laser pump/x-ray probe experiments

    Energy Technology Data Exchange (ETDEWEB)

    Larsson, J.; Judd, E.; Schuck, P.J. [Univ. of California, Berkeley, CA (United States)] [and others


    In an ongoing project aimed at probing solids using x-rays obtained at the ALS synchrotron with a sub-picosecond time resolution following interactions with a 100 fs laser pulse, the authors have successfully performed pump-probe experiments limited by the temporal duration of ALS-pulse. They observe a drop in the diffraction efficiency following laser heating. They can attribute this to a disordering of the crystal. Studies with higher temporal resolution are required to determine the mechanism. The authors have also incorporated a low-jitter streakcamera as a diagnostic for observing time-dependant x-ray diffraction. The streakcamera triggered by a photoconductive switch was operated at kHz repetition rates. Using UV-pulses, the authors obtain a temporal response of 2 ps when averaging 5000 laser pulses. They demonstrate the ability to detect monochromatized x-ray radiation from a bend-magnet with the streak camera by measuring the pulse duration of a x-ray pulse to 70 ps. In conclusion, the authors show a rapid disordering of an InSb crystal. The resolution was determined by the duration of the ALS pulse. They also demonstrate that they can detect x-ray radiation from a synchrotron source with a temporal resolution of 2ps, by using an ultrafast x-ray streak camera. Their set-up will allow them to pursue laser pump/x-ray probe experiments to monitor structural changes in materials with ultrafast time resolution.

  6. Enhanced efficiency of AlGaInP disk laser by in-well pumping. (United States)

    Mateo, C M N; Brauch, U; Schwarzbäck, T; Kahle, H; Jetter, M; Abdou Ahmed, M; Michler, P; Graf, T


    The performance of a 665-nm GaInP disk laser operated continuous-wave at 15°C both in-well-pumped at 640 nm and barrier pumped at 532 nm is reported. The efficiency with respect to the absorbed power was enhanced by 3.5 times when using a 640-nm pump instead of a 532-nm pump. In-well pumping which is based on the absorption of the pump photons within the quantum-well heterostructures of the gain region instead of short-wavelength absorption in the barrier and spacer regions reduces the quantum defect between pump and laser photon and hence the heat generation. A slope efficiency of 60% with respect to the absorbed pump power was obtained by in-well pumping at 15°C. Continuous-wave laser operation was further demonstrated at heat sink temperatures of up to 55°C. Both the measurement of photoluminescence and COMSOL simulation show that the overall heat load in the in-well pumped laser is smaller than in the barrier-pumped laser. These results demonstrate the potential of optical in-well pumping for the operation of red AlGaInP disk lasers if combined with means for efficient pump-light absorption.

  7. Rapid prototyping of a micro pump with laser micromachining (United States)

    Wong, C. Channy; Chu, Dahwey; Liu, Sally L.; Tuck, Melanie R.; Mahmud, Zahid; Amatucci, Vincent A.


    A microelectrohydrodynamic (EHD) injection pump has been developed using laser micromachining technoogy. Two desings have been fabricated, tested, and evaluated. The first design has two silicon pieces with KOH-etched wells which are stacked on the tpo of each other. The wells are etched on one side of the wafer and gold is deposited on the other side to serve as the pump electrodes. A Nd:YAG laser is used to drill an array of circular holes in the well region of both silicon parts. This creates a grid distribution with a square pattern. Next the well regions of the silicon parts are aligned, and the parts are bonded together using a Staystik thermoplastic. The pump unit is then mounted into a ceramic package with a large hole drilled in the bottom of the package to permit fluid flow. Aluminum ribbon wire bonds are used to connect the pump electrodes to the package leads. Isolation of metallization and wires is achieved by filling the package well and coating the wires with polyimide. When a voltage is applied at the electrodes, ions are injected into the working fluid, such as an organic solvent, thus inducing flow. The second design has the silicon parts oriented 'back-to-back' and bonded together with Stayform. A 'back-to-back' design will decrease the grid distance so that a smaller voltage is required for pumping. Preliminary results have demonstrated that this micropump can achieve a pressure head of about 287 Pa with an applied voltage of 120 Volt.

  8. Optimization of electron-beam pumped excimer laser (United States)

    Lowum, T. F.; Swecker, J. L.

    The output energy of an electron-beam pumped xenon flouride laser has been enhanced by optimizing certain electron-gun and gas-mix parameters. The optimized e-gun parameters include anode-cathode spacing, magnetic field strength, and cathode voltage. The optimized laser gas parameters include NF3 concentration, Xe concentration, and total pressure. The shortest anode-cathode spacing (9 cm), the strongest magnetic guide field (1600 Gauss), and the highest cathode voltage (375 kV) gave the highest laser output. The optimum gas concentrations were 0.05 percent NF3, 0.3 percent Xe, with Ne added to bring the total gas pressure to 60 psia. The energy degraded by 2 percent per shot with this gas mix.

  9. Optically pumped tunable HBr laser in the mid-infrared region

    CSIR Research Space (South Africa)

    Koen, W


    Full Text Available An optically pumped tunable HBr laser has been demonstrated for the first time. The pump source was a single-frequency Ho:YLF laser and amplifier system, which was locked to the 2064 nm absorption line of HBr. Laser oscillation was demonstrated...

  10. Superradiant dye solution laser with two-photon picosecond optical pumping

    Energy Technology Data Exchange (ETDEWEB)

    Prokhorenko, V.I.; Tikhonov, E.A.; Shpak, M.T.


    A superradiant (superfluorescent) dye solution laser with two-photon picosecond pumping was constructed for the first time. A preliminary study was made of the principal characteristics of the output radiation of this laser which performed up-conversion of the frequency of the pump radiation. The physical mechanisms governing the operation of lasers of this type were analyzed.

  11. Galactic evolution of D and $^{3}$He including stellar production of $^{3}$He

    CERN Document Server

    Dearborn, D S P; Tosi, M P


    New stellar models which track the production and destruction of ^3He (and D) have been evolved for a range of stellar masses (0.65\\leq M/M_{\\odot}\\leq 100), metallicities (0.01 \\leq Z/Z_{\\odot} \\leq 1) and initial (main sequence) ^3He mass fractions (10^{-5} \\leq X_{3,MS} \\leq 10^{-3}). Armed with the ^3He yields from these stellar models we have followed the evolution of D and ^3He using a variety of chemical evolution models with and without infall of primordial or processed material. Production of new ^3He by the lower mass stars overwhelms any reasonable primordial contributions and leads to predicted abundances in the presolar nebula and/or the present interstellar medium in excess of the observationally inferred values. This result, which obtains even for zero primordial D and ^3He, and was anticipated by Rood, Steigman \\& Tinsley (1976), is insensitive to the choice of chemical evolution model; it is driven by the large ^3He yields from low mass stars. In an attempt to ameliorate this problem we h...

  12. Development of laser diode-pumped high average power solid-state laser for the pumping of Ti:sapphire CPA system

    Energy Technology Data Exchange (ETDEWEB)

    Maruyama, Yoichiro; Tei, Kazuyoku; Kato, Masaaki; Niwa, Yoshito; Harayama, Sayaka; Oba, Masaki; Matoba, Tohru; Arisawa, Takashi; Takuma, Hiroshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment


    Laser diode pumped all solid state, high repetition frequency (PRF) and high energy Nd:YAG laser using zigzag slab crystals has been developed for the pumping source of Ti:sapphire CPA system. The pumping laser installs two main amplifiers which compose ring type amplifier configuration. The maximum amplification gain of the amplifier system is 140 and the condition of saturated amplification is achieved with this high gain. The average power of fundamental laser radiation is 250 W at the PRF of 200 Hz and the pulse duration is around 20 ns. The average power of second harmonic is 105 W at the PRF of 170 Hz and the pulse duration is about 16 ns. The beam profile of the second harmonic is near top hat and will be suitable for the pumping of Ti:sapphire laser crystal. The wall plug efficiency of the laser is 2.0 %. (author)

  13. Fiber laser pumped high power mid-infrared laser with picosecond pulse bunch output. (United States)

    Wei, Kaihua; Chen, Tao; Jiang, Peipei; Yang, Dingzhong; Wu, Bo; Shen, Yonghang


    We report a novel quasi-synchronously pumped PPMgLN-based high power mid-infrared (MIR) laser with picosecond pulse bunch output. The pump laser is a linearly polarized MOPA structured all fiberized Yb fiber laser with picosecond pulse bunch output. The output from a mode-locked seed fiber laser was directed to pass through a FBG reflector via a circulator to narrow the pulse duration from 800 ps to less than 50 ps and the spectral FWHM from 9 nm to 0.15 nm. The narrowed pulses were further directed to pass through a novel pulse multiplier through which each pulse was made to become a pulse bunch composing of 13 sub-pulses with pulse to pulse time interval of 1.26 ns. The pulses were then amplified via two stage Yb fiber amplifiers to obtain a linearly polarized high average power output up to 85 W, which were then directed to pass through an isolator and to pump a PPMgLN-based optical parametric oscillator via quasi-synchronization pump scheme for ps pulse bunch MIR output. High MIR output with average power up to 4 W was obtained at 3.45 micron showing the feasibility of such pump scheme for ps pulse bunch MIR output.

  14. Red laser-diode pumped 806 nm Tm3+: ZBLAN fibre laser (United States)

    Juárez-Hernández, M.; Mejía, E. B.


    A Tm3+-doped fluorozirconate (ZBLAN) fibre laser operating CW at 806 nm when diode-pumped at 687 nm is described for the first time. This device is based on the 3F4  →  3H6 transition, and is suitable for first telecom window and sensing applications. A slope efficiency of 50.3% and low threshold pump-power of 11.6 mW were obtained. Maximum output power of 15 mW for 40 mW coupled pump was achieved.

  15. Transverse modes of a diode-laser pumped monolithic unidirectional non-planar ring laser

    Institute of Scientific and Technical Information of China (English)

    Keying Wu(吴克瑛); Suhui Yang(杨苏辉); Guanghui Wei(魏光辉)


    Diode-laser pumped monolithic single-frequency non-planar ring laser has the advantages of compactness,reliability and high efficiency. But when the pump power is high enough, the thermal effect will be seriousand the high-order transverse modes will appear. Therefore the single-mode output power is limited. Inthis paper, the mechanism of generating the high-order transverse modes in the monolithic unidirectionalnon-planar ring cavity is analyzed using ray tracing method. The calculated results are in agreement withthe experiments.

  16. High-temperature diode laser pumps for directed energy fiber lasers (Conference Presentation) (United States)

    Kanskar, Manoj; Bao, Ling; Chen, Zhigang; DeVito, Mark; Dong, Weimin; Grimshaw, Mike P.; Guan, Xinguo; Hemenway, David M.; Martinsen, Robert; Zhang, Jim; Zhang, Shiguo


    Kilowatt-class fiber lasers and amplifiers are becoming increasingly important building blocks for power-scaling laser systems in various different architectures for directed energy applications. Currently, state-of-the-art Yb-doped fiber lasers operating near 1060 nm operate with optical-to-optical power-conversion efficiency of about 66%. State-of-the-art fiber-coupled pump diodes near 975 nm operate with about 50% electrical-to-fiber-coupled optical power conversion efficiency at 25C heatsink temperature. Therefore, the total system electrical-to-optical power conversion efficiency is about 33%. As a result, a 50-kW fiber laser will generate 75 kW of heat at the pump module and 25 kW at the fiber laser module with a total waste heat of 100 kW. It is evident that three times as much waste heat is generated at the pump module. While improving the efficiency of the diodes primarily reduces the input power requirement, increasing the operating temperature primarily reduces the size and weight for thermal management systems. We will discuss improvement in diode laser design, thermal resistance of the package as well as improvement in fiber-coupled optical-to-optical efficiency to achieve high efficiency at higher operating temperature. All of these factors have a far-reaching implication in terms of significantly improving the overall SWAP requirements thus enabling DEW-class fiber lasers on airborne and other platforms.

  17. Comparison of Nd:YAG Ceramic Laser Pumped at 885 nm and 808 nm

    Institute of Scientific and Technical Information of China (English)

    ZONG Nan; ZHANG Xiao-Fu; MA Qing-Lei; WANG Bao-Shan; CUI Da-Fu; PENG Qin-Jun; XU Zu-Yan; PAN Yu-Bai; FENG Xi-Qi


    Laser performance of 1064 nm domestic Nd: YA G ceramic lasers for 885 nm direct pumping and 808 nm traditional pumping are compared. Higher slope efficiency of 34% and maximum output power of 16.5 W are obtained for the 885nm pump with a 6ram length 1 at% Nd:YAG ceramic. The advantages for 885nm direct pumping are discussed in detail. This pumping scheme for highly doping a Nd:YAG ceramic laser is considered as an available way to generate high power and good beam quality simultaneously.

  18. 2-µm Tm:Lu₂O₃ ceramic disk laser intracavity-pumped by a semiconductor disk laser. (United States)

    Saarinen, Esa J; Vasileva, Elena; Antipov, Oleg; Penttinen, Jussi-Pekka; Tavast, Miki; Leinonen, Tomi; Okhotnikov, Oleg G


    A proof-of-principle study of a 1.97-µm Tm:Lu2O3 ceramic disk laser, intracavity pumped by a 1.2-µm semiconductor disk laser, is presented. The demonstrated concept allows for improved pump absorption and takes advantage of the broad wavelength coverage provided by semiconductor disk laser technology. For thin disk lasers the small thickness of the gain element typically leads to inefficient pump light absorption. This problem is usually solved by using a complex multi-pass pump arrangement. In this study we address this challenge with a new laser concept of an intracavity pumped ceramic thin disk laser. The output power at 1.97 µm was limited to 250 mW due to heat spreader-less mounting scheme of the ceramic gain disk.

  19. Powerful red-green-blue laser source pumped with a mode-locked thin disk laser. (United States)

    Brunner, Felix; Innerhofer, Edith; Marchese, Sergio V; Südmeyer, Thomas; Paschotta, Rüdiger; Usami, Takeshi; Ito, Hiromasa; Kurimura, Sunao; Kitamura, Kenji; Arisholm, Gunnar; Keller, Ursula


    We present a red-green-blue laser source with average powers of 8 W in the red, 23 W in the green, and 10.1 W in the blue. The entire pump power for the nonlinear conversion stages is provided by a single laser oscillator without any amplifier stages. Our system does not require any synchronized cavities, and all nonlinear crystals except one are critically phase matched at room temperature.

  20. The double-end-pumped cubic Nd:YVO4 laser: Temperature distribution and thermal stress

    Indian Academy of Sciences (India)

    P Elahi; S Morshedi


    Thermal effects of a double-end-pumped cubic Nd:YVO4 laser crystal are investigated in this paper. A detailed analysis of temperature distribution and thermal stress in cubic crystal with circular shape pumping is discussed. It has been shown that by considering the total input powers as constant, the double-end-pumped configurations with equal pump power can be considered as having a minimum thermal effect with respect to the other end-pumped configuration.

  1. Feasibility study of a sup 3 He-magnetometer for neutron electric dipole moment experiments

    CERN Document Server

    Borisov, Y; Leduc, M; Lobashev, V; Otten, E W; Sobolev, Y


    We report on a sup 3 He-magnetometer capable of detecting tiny magnetic field fluctuations of less than 10 sup - sup 1 sup 4 T in experiments for measuring the electric dipole moment (EDM) of the neutron. It is based on the Ramsey technique of separated oscillating fields and uses nuclear spin-polarized sup 3 He gas which is stored in two vessels of V approx =10 l in a sandwich-type arrangement around the storage bottle for ultra-cold neutrons (UCN). The gas is polarized by means of optical pumping in a separate, small discharge cell at pressures around 0.5 mbar and is then expanded into the actual magnetometer volume. To detect the polarization of sup 3 He gas at the end of the storage cycle the gas is pumped out by means of an oil-diffusion pump and compressed again into the discharge cell where optical detection of nuclear polarization is used.

  2. Reliable pump sources for high-energy class lasers (United States)

    Wölz, Martin; Pietrzak, Agnieszka; Kindsvater, Alex; Wolf, Jürgen; Meusel, Jens; Hülsewede, Ralf; Sebastian, Jürgen


    High-energy class laser systems operating at high average power are destined to serve fundamental research and commercial applications. System cost is becoming decisive, and JENOPTIK supports future developments with the new range of 500 W quasi-continuous wave (QCW) laser diode bars. In response to different strategies in implementing high-energy class laser systems, pump wavelengths of 880 nm and 940 nm are available. The higher power output per chip increases array irradiance and reduces the size of the optical system, lowering system cost. Reliability testing of the 880 nm laser diode bar has shown 1 Gshots at 500 W and 300 μs pulse duration, with insignificant degradation. Parallel operation in eight-bar diode stacks permits 4 kW pulse power operation. A new high-density QCW package is under development at JENOPTIK. Cost and reliability being the design criteria, the diode stacks are made by simultaneous soldering of submounts and insulating ceramic. The new QCW stack assembly technology permits an array irradiance of 12.5 kW/cm². We present the current state of the development, including laboratory data from prototypes using the new 500 W laser diode in dense packaging.

  3. Optically pumped planar waveguide lasers: Part II: Gain media, laser systems, and applications (United States)

    Grivas, Christos


    The field of optically pumped planar waveguide lasers has seen a rapid development over the last two decades driven by the requirements of a range of applications. This sustained research effort has led to the demonstration of a large variety of miniature highly efficient laser sources by combining different gain media and resonator geometries. One of the most attractive features of waveguide lasers is the broad range of regimes that they can operate, spanning from continuous wave and single frequency through to the generation of femtosecond pulses. Furthermore, their technology has experienced considerable advances to provide increased output power levels, deriving benefits from the relative immunity from the heat generated in the gain medium during laser operation and the use of cladding-pumped architectures. This second part of the review on optically pumped planar waveguide lasers provides a snapshot of the state-of-the-art research in this field in terms of gain materials, laser system designs, and as well as a perspective on the status of their application as real devices in various research areas.

  4. Low-threshold terahertz molecular laser optically pumped by a quantum cascade laser

    Directory of Open Access Journals (Sweden)

    A. Pagies


    Full Text Available We demonstrate a low-threshold, compact, room temperature, and continuous-wave terahertz molecular laser optically pumped by a mid-infrared quantum cascade laser. These characteristics are obtained, thanks to large dipole transitions of the active medium: NH3 (ammonia in gas state. The low-power (<60 mW laser pumping excites the molecules, thanks to intense mid-infrared transitions around 10.3 μm. The molecules de-excite by stimulated emission on pure inversion “umbrella-mode” quantum transitions allowed by the tunnel effect. The tunability of the quantum cascade laser gives access to several pure inversion transitions with different rotation states: we demonstrate the continuous-wave generation of ten laser lines around 1 THz. At 1.07 THz, we measure a power of 34 μW with a very low-threshold of 2 mW and a high differential efficiency of 0.82 mW/W. The spectrum was measured showing that the linewidth is lower than 1 MHz. To our knowledge, this is the first THz molecular laser pumped by a solid-state source and this result opens the way for compact, simple, and efficient THz source at room temperature for imaging applications.

  5. Fiber laser pumped burst-mode operated picosecond mid-infrared laser

    Institute of Scientific and Technical Information of China (English)

    魏凯华; 姜培培; 吴波; 陈滔; 沈永行


    We demonstrate a compact periodically poled MgO-doped lithium niobate (MgO:PPLN)-based optical parametric oscillator (OPO) quasi-synchronously pumped by a fiber laser system with burst-mode operation. The pump source is a peak-power-selectable pulse-multiplied picosecond Yb fiber laser. The chirped pulses from a figure of eight-cavity mode-locked fiber laser seed are narrowed to a duration of less than 50 ps using an FBG refl ector and a circulator. The narrowed pulses are directed to pass through a pulse multiplier and to form pulse bunches, each of which is composed of 13 sub-pulses. The obtained pulse bunches are amplified by two-stage fiber pre-amplifiers:one-stage is core-pumped and the other is cladding-pumped. A fiberized acousto–optic modulator is inserted to control the pulse repetition rate (PRR) of the pulse bunches before they are power-amplified in the final amplifier stage with a large mode area (LMA) PM Yb-doped fiber. The maximum average powers from the final amplifier are 85 W, 60 W, and 45 W respectively, corresponding to the PRR of 2.72 MHz, 1.36 MHz, and 0.68 MHz. The amplified pulses are directed to pump an MgO:PPLN-based optical parametric oscillator (OPO). A maximum peak power at 3.45 µm is obtained approximately to be 8.4 kW. Detailed performance characteristics are presented.

  6. DBR-free optically pumped semiconductor disk lasers (United States)

    Yang, Zhou; Albrecht, Alexander R.; Cederberg, Jeffrey G.; Sheik-Bahae, Mansoor


    Optically pumped semiconductor disk lasers (SDLs) provide high beam quality with high average-power power at designer wavelengths. However, material choices are limited by the need for a distributed Bragg reflector (DBR), usually monolithically integrated with the active region. We demonstrate DBR-free SDL active regions, which have been lifted off and bonded to various transparent substrates. For an InGaAs multi-quantum well sample bonded to a diamond window heat spreader, we achieved CW lasing with an output power of 2 W at 1150 nm with good beam quality.

  7. Runaway electron beam control for longitudinally pumped metal vapor lasers (United States)

    Kolbychev, G. V.; Kolbycheva, P. D.


    Physics and techniques for producing of the pulsed runaway electron beams are considered. The main obstacle for increasing electron energies in the beams is revealed to be a self- breakdown of the e-gun's gas-filled diode. Two methods to suppress the self-breakdown and enhance the volumetric discharge producing the e-beam are offered and examined. Each of them provides 1.5 fold increase of the ceiling potential on the gun. The methods also give the ways to control several guns simultaneously. Resulting in the possibility of realizing the powerful longitudinal pumping of metal-vapor lasers on self-terminated transitions of atoms or ions.

  8. Neutron scattering from solid 3He (United States)

    Schanen, R.; Sherline, T. E.; Toader, A. M.; Boyko, V.; Mat'as, S.; Meschke, M.; Schöttl, S.; Adams, E. D.; Cowan, B.; Godfrin, H.; Goff, J. P.; Roger, M.; Saunders, J.; Siemensmeyer, K.; Takano, Y.


    Multiple spin exchange leads, according to present understanding, to a variety of magnetically ordered states in solid 3He, depending on pressure and applied magnetic field. We report the status of experiments to directly determine these structures by neutron scattering. The large neutron absorption cross section, and associated sample heating, impose severe experimental demands on the design of the sample cell. We report on our proposed solution, including details of the sintered heat exchanger necessary to cool the sample, as well as the PrNi 5 nuclear demagnetization stage. The use of NMR in parallel experiments to characterise growth of the solid sample within the sinter is also discussed.

  9. Influence of absorbed pump profile on the temperature distribution within a diode side-pumped laser rod

    Indian Academy of Sciences (India)



    In this paper, an analytical model for temperature distribution of the side-pumped laser rod is extracted. This model can be used for side-pumped laser rods whose absorbed pump profile is a Gaussian profile. Then, it is validated by numerical results which exhibit a good agreement with the analytical results. Afterwards, by considering a general expression for super-Gaussian and top-hat profiles, and solving the heat equation, the influence of profile width and super-Gaussian exponent of the profile on temperature distribution are investigated.Consequently, the profile width turns out to have a greater influence on the temperature compared to the type of the profile.

  10. Influence of absorbed pump profile on the temperature distribution within a diode side-pumped laser rod (United States)

    Moghtader Dindarlu, M. H.; Tehrani, M. Kavosh; Saghafifar, H.; Maleki, A.; Solookinejad, Gh; Jabbari, M.


    In this paper, an analytical model for temperature distribution of the side-pumped laser rod is extracted. This model can be used for side-pumped laser rods whose absorbed pump profile is a Gaussian profile. Then, it is validated by numerical results which exhibit a good agreement with the analytical results. Afterwards, by considering a general expression for super-Gaussian and top-hat profiles, and solving the heat equation, the influence of profile width and super-Gaussian exponent of the profile on temperature distribution are investigated. Consequently, the profile width turns out to have a greater influence on the temperature compared to the type of the profile.

  11. Simple highly efficient pumping configuration in high-power thin-disk laser (United States)

    Seyedzamani, Sasan; Eslami, Esmaeil


    A simple high-power thin-disk pumping configuration using a radiation combination of four commercially available laser-diode stacks is introduced. Two setup modifications are presented to compensate the nonsuitable shape of the pumping spot arising from low beam quality in our combination method. The effects of setup modifications on pumping spot shapes are confirmed by ray tracing simulations using Trace-pro™ software. All setups are arranged in the laboratory, and the experimental measurements show pumping spots improvements on the disk due to modifications in agreement with simulation results. Output power measurements show that by adapting the pumping spot size to the disk cooling capacity the modified setups can deliver higher output powers and efficiencies. Furthermore, the modifications reduce the laser threshold and improve output laser beam quality. Hence, the modifications make the simple four laser-diodes beam combination applicable for thin-disk laser pumping.

  12. Pump-probe laser development for the European X-ray Free-Electron Laser facility (United States)

    Lederer, Max J.; Pergament, Mikhail; Kellert, Martin; Mendez, Cruz


    The successful implementation of superconducting LINAC technology at the European XFEL will boost the time averaged X-RAY power density substantially above current values. In fact, the XFEL will operate at repetition rates of up to 4.5MHz. However, this high pulse rate occurs only during 600μs long bursts of 10Hz repetition rate, rendering up to 27000 pulses per second. Matching this peculiar burst mode operation is a requirement also for the pump-probe femtosecond laser used in experiments. There is currently no commercially available femtosecond laser technology offering this kind of output at close to mJ-level energies per pulse and sub-20fs pulse width. We will outline the scheme of the pump-probe laser currently under development at the European XFEL. The laser design is based on a noncollinear optical parametric amplifier (NOPA) which will be pumped by sub-picosecond pulses from a high power, frequency-doubled Yb:YAG slab amplifier, delivering up to 20kW of fundamental average power during a burst. The design aims at highest possible flexibility regarding intra-burst rep-rates and pulse energies. Also, the use of uncompressed as well as compressed NOPA pump pulses at fundamental wavelength will enhance the flexibility in experiments.

  13. Laser emission from diode-pumped Nd:YAG ceramic waveguide lasers realized by direct femtosecond-laser writing technique. (United States)

    Salamu, Gabriela; Jipa, Florin; Zamfirescu, Marian; Pavel, Nicolaie


    We report on realization of buried waveguides in Nd:YAG ceramic media by direct femtosecond-laser writing technique and investigate the waveguides laser emission characteristics under the pump with fiber-coupled diode lasers. Laser pulses at 1.06 μm with energy of 2.8 mJ for the pump with pulses of 13.1-mJ energy and continuous-wave output power of 0.49 W with overall optical efficiency of 0.13 were obtained from a 100-μm diameter circular cladding waveguide realized in a 0.7-at.% Nd:YAG ceramic. A circular waveguide of 50-μm diameter yielded laser pulses at 1.3 μm with 1.2-mJ energy.

  14. Continuous-wave theory of Yb:YAG end-pumped thin-disk lasers. (United States)

    Jafari, Ahmad Khayat; Aas, Mehdi


    The fundamental principles of the operation of a thin-disk laser are presented. We derived equations from a set of coupled rate equations that predict that the characteristics of a laser are affected by the Boltzmann occupation factors of the pump and the laser states simultaneously. The model is used to investigate the influence of the effective parameters on the operational efficiency of an end-pumped Yb:YAG disk laser. Based on our results, we examined laser output power as a function of output coupler reflectivity, crystal thickness or doping concentration, number of the pump beam passes, and temperature.

  15. Challenges of high power diode-pumped lasers for fusion energy

    Institute of Scientific and Technical Information of China (English)

    Bruno; Le; Garrec


    This paper reviews the different challenges that are encountered in the delivery of high power lasers as drivers for fusion energy.We will focus on diode-pumped solid-state lasers and we will highlight some of the main recent achievements when using ytterbium,cryogenic cooling and ceramic gain media.Apart from some existing fusion facilities and some military applications of diode-pumped solid-state lasers,we will show that diode-pumped solid-state lasers are scalable to inertial fusion energy(IFE)’s facility level and that the all-fiber laser scheme is very promising.

  16. Improving Lifetime of Quasi-CW Laser Diode Arrays for Pumping 2-Micron Solid State Lasers (United States)

    Amzajerdian, Farzin; Meadows, Byron L.; Baker, Nathaniel R.; Barnes, Bruce W.; Singh, Upendra N.; Kavaya, Michael J.


    Operating high power laser diode arrays in long pulse regime of about 1 msec, which is required for pumping 2-micron thulium and holmium-based lasers, greatly limits their useful lifetime. This paper describes performance of laser diode arrays operating in long pulse mode and presents experimental data on the active region temperature and pulse-to-pulse thermal cycling that are the primary cause of their premature failure and rapid degradation. This paper will then offer a viable approach for determining the optimum design and operational parameters leading to the maximum attainable lifetime.

  17. Partially end-pumped Nd:YAG slab laser with a hybrid resonator. (United States)

    Du, K; Wu, N; Xu, J; Giesekus, J; Loosen, P; Poprawe, R


    A Nd:YAG slab is partially end pumped by a diode laser stack with three diode laser bars. The pumped volume has a rectangular cross section. A hybrid resonator, which is stable in the plane of small dimension and is off-axis unstable in the plane of large dimension of the gain cross section, was used to yield highly efficient laser operation at diffraction-limited beam quality. The laser design and experimental results are reported.

  18. Diode-pumped double passively Q-switched Nd:GdVO4 laser

    Institute of Scientific and Technical Information of China (English)

    LIU Min; LIU Shu-shan; LI Lei; WANG Wei-wei; CHEN Fei; LIU Jie


    Through using both Cr4+:YAG and GaAs saturable absorbers, a diode-pumped double passively Q-switched Nd:GdVO4 laser is realized and compared with a single passively Q-switched laser. This laser can generate symmetric pulse temporal profiles and shorter pulses. A laser pulse width of 17 ns has been achieved with the incident pump power of 8.5 W.

  19. Hyperfine Structure Measurements of Antiprotonic $^3$He using Microwave Spectroscopy

    CERN Document Server

    Friedreich, Susanne

    The goal of this project was to measure the hyperfine structure of $\\overline{\\text{p}}^3$He$^+$ using the technique of laser-microwave-laser spectroscopy. Antiprotonic helium ($\\overline{\\text{p}}$He$^+$) is a neutral exotic atom, consisting of a helium nucleus, an electron and an antiproton. The interactions of the angular momenta of its constituents cause a hyperfine splitting ({HFS}) within the energy states of this new atom. The 3\\% of formed antiprotonic helium atoms which remain in a metastable, radiative decay-dominated state have a lifetime of about 1-3~$\\mu$s. This time window is used to do spectroscopic studies. The hyperfine structure of $\\overline{\\text{p}}^4$He$^+$ was already extensively investigated before. From these measurements the spin magnetic moment of the antiproton can be determined. A comparison of the result to the proton magnetic moment provides a test of {CPT} invariance. Due to its higher complexity the new exotic three-body system of $\\overline{\\text{p}}^3$He$^+$ is a cross-check...

  20. Laser emission from a solar-pumped fiber. (United States)

    Mizuno, Shintaro; Ito, Hiroshi; Hasegawa, Kazuo; Suzuki, Takenobu; Ohishi, Yasutake


    We report the realization of a solar-pumped fiber laser (SPFL) using a double-clad (a center core/ an inner clad working also as optical waveguide/ an outer clad) Nd-doped fluoride optical fiber as a laser medium. With a compact off-axis parabolic mirror of 5 cm in aperture diameter, the natural sunlight is concentrated by a factor 10⁴, and introduced partly into the core of the fiber and partly into the inner clad in which the light is guided in some distance and transferred to the core after all. We have obtained clear laser spectrum characteristics with approximately 0.01 nm full-width-half-maximum of the laser line at the peak wavelength of 1053.7 nm, a low-lasing threshold of 49.1 mW, a slope efficiency of 6.6%, and a total efficiency of 1.76%. Further optimization of the medium properties, optical cavity, and concentration technique will yield higher efficiency and lower threshold.

  1. Two-Photon-Pumped Perovskite Semiconductor Nanocrystal Lasers. (United States)

    Xu, Yanqing; Chen, Qi; Zhang, Chunfeng; Wang, Rui; Wu, Hua; Zhang, Xiaoyu; Xing, Guichuan; Yu, William W; Wang, Xiaoyong; Zhang, Yu; Xiao, Min


    Two-photon-pumped lasers have been regarded as a promising strategy to achieve frequency up-conversion for situations where the condition of phase matching required by conventional approaches cannot be fulfilled. However, their practical applications have been hindered by the lack of materials holding both efficient two-photon absorption and ease of achieving population inversion. Here, we show that this challenge can be tackled by employing colloidal nanocrystals of perovskite semiconductors. We observe highly efficient two-photon absorption (with a cross section of 2.7 × 10(6) GM) in toluene solutions of CsPbBr3 nanocrystals that can excite large optical gain (>500 cm(-1)) in thin films. We have succeeded in demonstrating stable two-photon-pumped lasing at a remarkable low threshold by coupling CsPbBr3 nanocrystals with microtubule resonators. Our findings suggest perovskite nanocrystals can be used as excellent gain medium for high-performance frequency-up-conversion lasers toward practical applications.

  2. Measurement of heat pump processes induced by laser radiation (United States)

    Garbuny, M.; Henningsen, T.


    A series of experiments was performed in which a suitably tuned CO2 laser, frequency doubled by a Tl3AsSe37 crystal, was brought into resonance with a P-line or two R-lines in the fundamental vibration spectrum of CO. Cooling or heating produced by absorption in CO was measured in a gas-thermometer arrangement. P-line cooling and R-line heating could be demonstrated, measured, and compared. The experiments were continued with CO mixed with N2 added in partial pressures from 9 to 200 Torr. It was found that an efficient collisional resonance energy transfer from CO to N2 existed which increased the cooling effects by one to two orders of magnitude over those in pure CO. Temperature reductions in the order of tens of degrees Kelvin were obtained by a single pulse in the core of the irradiated volume. These measurements followed predicted values rather closely, and it is expected that increase of pulse energies and durations will enhance the heat pump effects. The experiments confirm the feasibility of quasi-isentropic engines which convert laser power into work without the need for heat rejection. Of more immediate potential interest is the possibility of remotely powered heat pumps for cryogenic use, such applications are discussed to the extent possible at the present stage.

  3. Polarization/Spatial Combining of Laser-Diode Pump Beams (United States)

    Gelsinger, Paul; Liu, Duncan


    A breadboard version of an optical beam combiner is depicted which make it possible to use the outputs of any or all of four multimode laser diodes to pump a non-planar ring oscillator (NPRO) laser. The output of each laser diode has a single-mode profile in the meridional plane containing an axis denoted the 'fast' axis and a narrower multimode profile in the orthogonal meridional plane, which contains an axis denoted the 'slow' axis and a narrower multimode profile in the orthogonal meridional plane, which contains an axis denoted the 'slow' axis. One of the purposes served by the beam-combining optics is to reduce the fast-axis numerical aperture (NA) of the laser-diode output to match the NA of the optical fiber. Along the slow axis, the unmodified laser-diode NA is already well matched to the fiber optic NA, so no further slow-axis beam shaping is needed. In this beam combiner, the laser-diode outputs are collimated by aspherical lenses, then half-wave plates and polarizing beam splitters are used to combine the four collimated beams into two beams. Spatial combination of the two beams and coupling into the optical fiber is effected by use of anamorphic prisms, mirrors, and a focusing lens. The anamorphic prisms are critical elements in the NA-matching scheme, in that they reduce the fast-axis beam width to 1/6 of its original values. Inasmuch as no slow-axis beam shaping is needed, the collimating and focusing lenses are matched for 1:1 iumaging. Because these lenses are well corrected for infinite conjugates the combiner offers diffraction-limited performance along both the fast and slow axes.

  4. PREFACE: JCNS Workshop on Modern Trends in Production and Applications of Polarized 3He (United States)

    Ioffe, Alexander; Babcock, Earl; Gutberlet, Thomas


    Polarized neutron scattering techniques are an indispensable and highly requested tool for studying magnetic phenomena in condensed matter. The different coherent and incoherent scattering of isotopes such as protons and deuterons also allows applications of polarized neutrons in soft matter and biological studies of molecular and macromolecular dynamics. One method to polarize neutrons is to use polarized 3He gas which absorbs, or filters, one spin state of the neutron beam as it passes through it. Only about ten years ago, early polarized neutron scattering experiments using such 3He neutron spin filters (3He NSF) were being conducted using starting 3He polarizations of 55%. Currently there are two different commonly used methods to polarize high quantities of 3He. These methods both collisionally transfer spin polarization to ground state 3He nucleuses; one method uses optical pumping of an excited metastable state of 3He atoms, and the other uses optical pumping of the ground state of an alkali-metal vapour. Within the last decade immense progress in both methods has resulted in 3He polarizations of up to 80% being reported in atmosphere-pressure 3He cells by the world's leading labs. This progress in optical pumped 3He promises to give rise to much more efficient and novel polarized neutron scattering experiments as and also impacts other areas of science. Polarized 3He is additionally applied in research fields such as particle physics, fundamental studies and medicine. Thus not only the techniques and methods of polarization, but the research groups themselves exploring polarized 3He, have a large breadth and diversity spanning different fields of science and locations in the world. Given this diversity, it is rare for this community to meet as a group at any one meeting or conference. Because it is crucial to discuss new developments in 3He polarization in a multi-disciplinary international setting, an international workshop on "Modern Trends in Production

  5. Detection of D-^3He Fusion γ-Rays using Gas Cherenkov Detectors (United States)

    Kim, Y.; Herrmann, H. W.; Mack, J. M.; Young, C. S.; Hale, G. M.; Evans, S. C.; Sedillo, T. J.; Cahill, A.; Horsfield, C. J.; Rubery, M. S.; Grafil, E.; Stoeffl, W.; Waugh, C.; Rinderknecht, H. G.; Frenje, J. A.; Petrasso, R. D.; Miller, E. Kirk


    The high-energy γ-ray from ^3He(d,γ)^5Li reactions has drawn the attention of the nuclear physics and fusion community as a diagnostic signature to study the ^5Li nuclear structure and the D-^3He fusion reaction. In the past, the D-^3He γ-rays have been measured via accelerator-based beam-target experiments and recently in tokamak-based fusion reactors. In this work, we report the detection of D-^3He fusion γ-rays generated from inertial confinement fusion (ICF) implosions at the OMEGA laser facility. The γ-ray signal observed using Gas Cherenkov Detectors (GCD) is proportional to the independently measured 14.7-MeV fusion proton yield and provides a high-bandwidth alternative to fusion protons for D-^3He burn-history measurements. By comparing γ-rays from D-^3He and D-T implosions, we were able to examine (1) similarities in the γ-ray spectra of D-^3He and D-T and (2) disparities in the γ-to-particle branching ratios of D-^3He and D-T. This experimental work motivates further theoretical investigation of the multichannel ^5Li- and ^5He-system.

  6. Functional possibilities for forming different inverse population distributions in diode-side-pumped laser heads

    Energy Technology Data Exchange (ETDEWEB)

    Grechin, S G; Nikolaev, P P; Sharandin, E A [N.E. Bauman Moscow State Technical University, Moscow (Russian Federation)


    The functional possibilities of diode-side-pumped laser heads of solid-state lasers for forming inverse population distributions of different types are analysed. The invariants determining the relationship between the laser head parameters upon scaling are found. The results of comparative experimental studies are presented. (lasers)

  7. Theoretical and Experimental studies on CH{sub 3}OH THz Laser Pumped by Pulse Carbon Dioxide Laser

    Energy Technology Data Exchange (ETDEWEB)

    Fei Fei; Wang Jing; Tian Zhaoshuo; Zhang Yanchao; Fu Shiyou; Wang Qi, E-mail: [Information Optoelectronics Research Institute, Harbin Institute of Technology at Weihai, Sandong, Weihai, 264209 (China)


    In this paper, according to the molecular structure and vibration mode of micro-asymmetric gyroscope CH{sub 3}OH molecule, dynamic process of optically pumped Terahertz laser is analyzed theoretically. The rate equation models based on three level systems are given according to the theory of typical laser rate equation. The output THz pulsed laser waveform is obtained by solving the rate equation model. An all-metal Terahertz laser pumped by RF waveguide carbon dioxide laser is designed with CH{sub 3}OH as its working gas. The pulsed Terahertz laser output is obtained. The waveform and repetition frequency of the optically pumped laser are measured in the experiments. The Terahertz laser designed does not need water cooling system. It also has the advantages of simple structure and small size.

  8. 407 W End-pumped Multi-segmented Nd:YAG Laser. (United States)

    Kracht, Dietmar; Wilhelm, Ralf; Frede, Maik; Dupré, Klaus; Ackermann, Lothar


    A composite crystalline Nd:YAG rod consisting of 5 segments with different dopant concentrations for high power diode end-pumping is presented. A maximum laser output power of 407 W with an optical-to-optical efficiency of 54 % was achieved by longitudinal pumping with a high power laser diode stack.

  9. High efficient diode-pumped Tm:YAP laser at room temperature

    Institute of Scientific and Technical Information of China (English)

    Yufeng Li; Baoquan Yao; Yuezhu Wang; Youlun Ju; Guangjun Zhao; Yanhua Zong; Jun Xu


    A high efficient diode-pumped Tm:YAP laser is reported. The maximum output power at 1981 nm is 5.2 W and the slope efficiency is 30%. Unpolarized absorption near 800 nm and unpolarized fluorescence spectra near 1800 nm pumped by laser diode (LD) are measured. In addition, the relationship between operation temperature and output power is discussed.

  10. Single-frequency operation of a diode-pumped green laser using multi-Brewster plates

    Institute of Scientific and Technical Information of China (English)

    Quan Zheng(郑权); Ling Zhao(赵岭); Longsheng Qian(钱龙生)


    In a diode-pumped, KTP intracavity frequency-doubled green laser, multi-Brewster plates are used toachieve high power single-frequency operation. With a simple experimental setup, single-frequency opera-tion of the diode-pumped green laser with output of 46 and 218 mW is obtained by one and three Brewsterplate, respectively.

  11. Recent advances in polarized 3 He based neutron spin filter development (United States)

    Chen, Wangchun; Gentile, Thomas; Erwin, Ross; Watson, Shannon; Krycka, Kathryn; Ye, Qiang; NCNR NIST Team; University of Maryland Team


    Polarized 3 He neutron spin filters (NSFs) are based on the strong spin-dependence of the neutron absorption cross section by 3 He. NSFs can polarize large area, widely divergent, and broadband neutron beams effectively and allow for combining a neutron polarizer and a spin flipper into a single polarizing device. The last capability utilizes 3 He spin inversion based on the adiabatic fast passage (AFP) nuclear magnetic resonance technique. Polarized 3 He NSFs are significantly expanding the polarized neutron measurement capabilities at the NIST Center for Neutron Research (NCNR). Here we present an overview of 3 He NSF applications to small-angle neutron scattering, thermal triple axis spectrometry, and wide-angle polarization analysis. We discuss a recent upgrade of our spin-exchange optical pumping (SEOP) systems that utilize chirped volume holographic gratings for spectral narrowing. The new capability allows us to polarize rubidium/potassium hybrid SEOP cells over a liter in volume within a day, with 3 He polarizations up to 88%, Finally we discuss how we can achieve nearly lossless 3 He polarization inversion with AFP.

  12. Recent advancements of wide-angle polarization analysis with 3He neutron spin filters (United States)

    Chen, W. C.; Gentile, T. R.; Ye, Q.; Kirchhoff, A.; Watson, S. M.; Rodriguez-Rivera, J. A.; Qiu, Y.; Broholm, C.


    Wide-angle polarization analysis with polarized 3He based neutron spin filters (NSFs) has recently been employed on the Multi-Axis Crystal Spectrometer (MACS) at the National Institute of Standards and Technology Center for Neutron Research (NCNR). Over the past several years, the apparatus has undergone many upgrades to address the fundamental requirements for wide angle polarization analysis using spin exchange optical pumping based 3He NSFs. In this paper, we report substantial improvements in the on-beam-line performance of the apparatus and progress toward routine user capability. We discuss new standard samples used for 3He NSF characterization and the flipping ratio measurement on MACS. We further discuss the management of stray magnetic fields produced by operation of superconducting magnets on the MACS instrument, which can significantly reduce the 3He polarization relaxation time. Finally, we present the results of recent development of horseshoe-shaped wide angle cells.

  13. The effect of incident angle of pumping light on Cholesteric Liquid Crystal tunable laser wavelength

    CERN Document Server

    Yin, Xiangbao


    One notable feature of dye doped cholesteric liquid crystal is the variation of pitch and refractive index as the incidence angle of the pumping light shifts. Based on this feature, this paper studies the effects of pumping light's incidence angle on emission properties of the dye doped cholesteric liquid crystal tunable laser. First, we investigated the relationship among the concentration of chiral reagent, the incidence angle of the pumping light, and the pitch of liquid-crystal display (LCD); then we made a tunable-wavelength laser and pumped the prepared sample with 532nm laser outputted from the Nd: YAG multi-frequency pulse laser. As the incident angle of the pumping light shifts between 20 {\\deg} ~ 90 {\\deg}, the tuning range of the wavelength emitted by the laser reaches 10.73nm, ranging between 647.38nm and 658.11nm.

  14. High-average-power diode-pumped Yb: YAG lasers

    Energy Technology Data Exchange (ETDEWEB)

    Avizonis, P V; Beach, R; Bibeau, C M; Emanuel, M A; Harris, D G; Honea, E C; Monroe, R S; Payne, S A; Skidmore, J A; Sutton, S B


    A scaleable diode end-pumping technology for high-average-power slab and rod lasers has been under development for the past several years at Lawrence Livermore National Laboratory (LLNL). This technology has particular application to high average power Yb:YAG lasers that utilize a rod configured gain element. Previously, this rod configured approach has achieved average output powers in a single 5 cm long by 2 mm diameter Yb:YAG rod of 430 W cw and 280 W q-switched. High beam quality (M{sup 2} = 2.4) q-switched operation has also been demonstrated at over 180 W of average output power. More recently, using a dual rod configuration consisting of two, 5 cm long by 2 mm diameter laser rods with birefringence compensation, we have achieved 1080 W of cw output with an M{sup 2} value of 13.5 at an optical-to-optical conversion efficiency of 27.5%. With the same dual rod laser operated in a q-switched mode, we have also demonstrated 532 W of average power with an M{sup 2} < 2.5 at 17% optical-to-optical conversion efficiency. These q-switched results were obtained at a 10 kHz repetition rate and resulted in 77 nsec pulse durations. These improved levels of operational performance have been achieved as a result of technology advancements made in several areas that will be covered in this manuscript. These enhancements to our architecture include: (1) Hollow lens ducts that enable the use of advanced cavity architectures permitting birefringence compensation and the ability to run in large aperture-filling near-diffraction-limited modes. (2) Compound laser rods with flanged-nonabsorbing-endcaps fabricated by diffusion bonding. (3) Techniques for suppressing amplified spontaneous emission (ASE) and parasitics in the polished barrel rods.

  15. Efficient Pumping Scheme by Direct Excitation of Upper Laser Level in Nd:CNGG

    Institute of Scientific and Technical Information of China (English)

    CAO Ning; HE Kun-Na; GAO Chun-Qing; LI Qi-Nan; ZHAO Yan-Ying; XU Chang-Wen; WEI Zhi-Yi; FENG Bao-Hua; ZHANG Zhi-Guo; ZHANG Huai-Jin; WANG Ji-Yang


    We report an efficient pumping scheme which involves a direct excitation of the upper lasing level of a four-level laser in a Nd-doped Ca3(NbGa)2-xGa3O12 (Nd:CNGG) by using a tunable Ti:sapphire, 700-920nm, cw pump source. The slope efficiency is improved from 10.5% of the traditional band pumping at 808nm to 21.8% of the direct pumping at 882nm. The influence of pumping wavelength on lasing is discussed. We present a scheme of double pumping for lasing.

  16. Laser Diode Pumped 1.54μm Er:Yb:Phosphate Glass Continuous Wave Compact Laser

    Institute of Scientific and Technical Information of China (English)

    孟凡臻; 宋峰; 张潮波; 丁欣; 商美茹; 张光寅


    We report a cw Er3+ :Yb3+ co-doped phosphate glass laser pumped by a laser diode. The maximum output power of 78.3mW and a slope efficiency of 15.25% were achieved. The laser spectral region was from 1532nm to 1535nm, with the peak laser wavelength at 1534nm. The laser modes and time stability were also measured.The thermal effect had little influence on the output in our experiment.

  17. Penning neon plasma laser pumped by a compact accelerator

    Energy Technology Data Exchange (ETDEWEB)

    Derzhiev, V.I.; Zhidkov, A.G.; Koval' , A.V.; Skakun, V.S.; Tarasenko, V.F.


    A study is made of the emission characteristics of a neon laser (wavelengths, 585.3, 724.5, and 703.2 nm) in the afterglow (50-120 ns) of a plasma generated by a short (less than 10 ns) electron beam pulse (20-100 A/sq cm) during the longitudinal and transverse pumping of dense (0.5-3 atm) He-Ne-Ar(Kr) and Ne-H2 mixtures. It is shown experimentally that preheating has a negative effect on the lasing characteristics. The relaxation kinetics of the He-Ne-Ar mixture and the emission characteristics of the neon yellow line are calculated; the results are in good agreement with measured lasing characteristics. 7 references.

  18. Laser pumped (4)He magnetometer with light shift suppression. (United States)

    Lin, Zaisheng; Wang, He; Peng, Xiang; Wu, Teng; Guo, Hong


    We report a laser-pumped (4)He atomic magnetometer with light shift suppression through the atomic sensor itself. A linearly polarized light is used to optically align the (4)He metastable atoms and we monitor the magneto-optical double resonance (MODR) signals produced by the left- and right-circularly orthogonal components. It is shown that light shift leads to the atomic alignment to orientation conversion effect, and thus, the difference between the two MODR signals. One of these two MODR signals is locked at the Larmor frequency and is used to measure the ambient magnetic field, while the differential signal is, simultaneously, fed back to suppress the light shift. The scheme could be of the advantage to the design of compact magnetometers by reducing the systematic errors due to light shift.

  19. Measurements of enlarged blood pump models using Laser Doppler Anemometer. (United States)

    Chua, L P; Yu, S C; Leo, H L


    In an earlier study (Chua et al., 1998, 1999a), a 5:1 enlarged model of the Kyoto-NTN Magnetically Suspended Centrifugal Blood Pump (Akamatsu et al., 1995) with five different impeller blade profiles was designed and constructed. Their respective flow characteristics with respect to (1) the three different blade profile designs: forward, radial, and backward, (2) the number of blades used, and (3) the rotating speed were investigated. Among the five impeller designs, the results obtained suggested that impellers A and C designs should be adopted if higher head is required. Impellers A and C therefore were selected for the flow in between their blades to be measured using Laser Doppler Anemometer (LDA), so as to have a better understanding of the flow physics with respect to the design parameters.

  20. Low-power photolytically pumped lasers: Final technical report

    Energy Technology Data Exchange (ETDEWEB)

    Messing, I.; Lorents, D.C.; Eckstrom, D.J.


    We have carried out an extensive series of measurements of the time-resolved Xe/sub 2/* emission spectra following optical pumping by a short-pulse F/sub 2/ laser at 157.6 nm. Most measurements were performed using a gated Optical Multichannel Analyzer detector; we also made measurements using a scanning monochromator fitted with a photomultiplier and using a boxcar integrator for time resolution. The two sets of results agree well and show that both the singlet and triplet emission bands are broader than expected and have center wavelengths closer together than expected. Measurements were performed both at room temperature and at elevated (140/sup 0/C) and reduced (-27/sup 0/C) temperatures. The broad bandwidth of the individual spectral bands was unexpected and conflicted with a previous spectral measurement using optical pumping by the Xe* resonance line from a microwave discharge lamp. Therefore, we also performed a series of spectral measurements using this type of optical pumping. We achieved good agreement with some previous results in the literature, but not with the result in question. We conclude that the present results are reliable. The results presented in this report provide the first definitive measurement of the individual excimer emissions from each of the Xe/sub 2/(0/sub u//sup +/) and Xe/sub 2/(1/sub u/) states. From these measurements and the known ground state potential, we derived a 1/sub u/ potential that reproduces the emission band very well. However, the 1/sub u/ potential is in substantial disagreement with the recent 1/sub u/ potential derived by the Toronto group. 13 refs., 32 figs., 3 tabs.

  1. Nd:GGG disk laser with multipoint spatially periodic optical pumping (United States)

    Guryev, D. A.; Nikolaev, D. A.; Tsvetkov, V. B.


    The results of the study of the output laser beam spatial characteristics of the Nd:Gd3Ga5O12 (Nd:GGG) disk laser with multipoint spatially periodic diode-pumping are presented. The presence of the optical coupling between the TEM00 lasing channels is demonstrated. The phase-locking of channels was realized due to partial overlapping of laser beams inside the pumped areas of the active element disk.

  2. Continuous-wave operation of a room-temperature Tm: YAP-pumped Ho: YAG laser

    Institute of Scientific and Technical Information of China (English)


    We report a continuous-wave (CW) 2.1-μm Ho:YAG laser operating at room temperature pumped by a diode-pumped 1.94-?m Tm:YAP laser.The maximum output power of 1.5 W is obtained from Ho:YAG laser,corresponding to Tm-to-Ho slope efficiency of 17.9% and diode-to-He conversion efficiency of 5.6%.

  3. Diode-pumped, All-solid-state Cr: LiSGaF Laser

    Institute of Scientific and Technical Information of China (English)

    DAI Jianming; ZHANG Lizhe; ZHANG Weili; CHAI Lu; WANG Yong; XING Qirong; WANG Qingyue


    A compact and efficient CW Cr: LiSGaF laser pumped by two 670 nm laser diodes was reported. Average power as high as 125 mW was generated with a absorbed pump power of 800 mW. The slope efficiency was 17.2%, and the threshold was 72 mW. The tunability of the laser in detail was investigated and a tuning range of 100 nm from 790 to 890 nm was obtained.

  4. Continuously tunable solution-processed organic semiconductor DFB lasers pumped by laser diode

    DEFF Research Database (Denmark)

    Klinkhammer, Sönke; Liu, Xin; Huska, Klaus


    The fabrication and characterization of continuously tunable, solution-processed distributed feedback (DFB) lasers in the visible regime is reported. Continuous thin film thickness gradients were achieved by means of horizontal dipping of several conjugated polymer and blended small molecule...... solutions on cm-scale surface gratings of different periods. We report optically pumped continuously tunable laser emission of 13 nm in the blue, 16 nm in the green and 19 nm in the red spectral region on a single chip respectively. Tuning behavior can be described with the Bragg-equation and the measured...

  5. Diode Laser Pumped Alkali Vapor Lasers with Exciplex-Assisted Absorption (United States)


    Torr of Helium in the discharge is similar to the DPAL systems, o 13 = 7.2 x 10’ 13 cm2. The state degeneracy’s of, g3 =7, g2 =3 and g1 = 5 are more...krypton and helium was used . These gases were further purified by passage through molecular sieve traps that were immersed in liquid nitrogen. The total...was produced from a dye laser pumped by the 308 nm output of an excimer laser running at 10 Hz (Lambda Physik EMG201/FL3002). The linewidth was

  6. {eta} photoproduction off {sup 3}He

    Energy Technology Data Exchange (ETDEWEB)

    Witthauer, Lilian [Department of Physics, University Basel (Switzerland)


    Quark models predict many more states in the excitation spectrum of the nucleon than observed in experiments. Most previous experiments investigating the excitation spectrum of nucleons are based on elastic scattering of charged pions. This makes it probable that the data is biased against states that couple only weakly to N{pi}. Hence, one can study different excitation mechanisms and channels as the photoproduction of mesons via excitation of nucleon resonances. Measurements at ELSA in Bonn investigated the quasi-free {eta} photoproduction off the neutron (I. Jaegle et al., Phys. Rev. Lett 100 (2008) 252002). The resulting cross section shows a narrow structure at W=1.68 GeV with a width smaller than 60 MeV. This structure is only visible in the cross section on the neutron and not in that on the proton. Experiments of the GRAAL collaboration (V.Kuznetsov et al., arXiv:hep-ex/0606065v2) and LNS-Sendai (F. Miyahara et al., Prog. Theor. Phys. Suppl. 168 (2007) 90) showed the same effect in quasi-free photoproduction off the deuteron. In order to exclude any possibility that the structure could arise from nuclear effects (re-scattering of mesons, final state interaction) we have studied it for a nucleon system with different momentum distribution and different neutron/proton ratio, namely {sup 3}He. Preliminary results for the quasi-free {eta} cross section obtained in coincidence with recoil nucleons will be discussed.

  7. Optically pumped alkali laser and amplifier using helium-3 buffer gas (United States)

    Beach, Raymond J.; Page, Ralph; Soules, Thomas; Stappaerts, Eddy; Wu, Sheldon Shao Quan


    In one embodiment, a laser oscillator is provided comprising an optical cavity, the optical cavity including a gain medium including an alkali vapor and a buffer gas, the buffer gas including .sup.3He gas, wherein if .sup.4He gas is also present in the buffer gas, the ratio of the concentration of the .sup.3He gas to the .sup.4He gas is greater than 1.37.times.10.sup.-6. Additionally, an optical excitation source is provided. Furthermore, the laser oscillator is capable of outputting radiation at a first frequency. In another embodiment, an apparatus is provided comprising a gain medium including an alkali vapor and a buffer gas including .sup.3He gas, wherein if .sup.4He gas is also present in the buffer gas, the ratio of the concentration of the .sup.3He gas to the .sup.4He gas is greater than 1.37.times.10.sup.-6. Other embodiments are also disclosed.

  8. Dynamics of an erbium-doped fiber laser with pump modulation: theory and experiment (United States)

    Pisarchik, Alexander N.; Kir'yanov, Alexander V.; Barmenkov, Yuri O.; Jaimes-Reátegui, Rider


    We study in detail the complex dynamics of an erbium-doped fiber laser that has been subjected to harmonic modulation of a diode pump laser. We introduce a novel laser model that describes perfectly all experimentally observed features. The model is generalized to a nonlinear oscillator. The coexistence of different periodic and chaotic regimes and their relation to subharmonics and higher harmonics of the relaxation oscillation frequency of the laser are demonstrated with codimensional-one and codimensional-two bifurcation diagrams in parameter space of the modulation frequency and amplitude. The phase difference between the laser response and the pump modulation is also investigated.

  9. Reactions pd-->3He η and pd-->3He π+π- near the η threshold (United States)

    Mayer, B.; Boudard, A.; Fabbro, B.; Garçon, M.; Kerboul, C.; Poitou, J.; Wellers, F.; Jacobs, W. W.; Saudinos, J.; Tomasi-Gustafsson, E.; Mouly, J. P.; Kessler, R. S.; Nefkens, B. M.; Tippens, B.; van der Schaaf, A.; Abegg, R.; van Oers, W. T.; Briscoe, W.; Petrov, A.; Moalem, A.


    The reaction pd-->3Heη has been studied with the SPES2 spectrometer, for proton energies between 0.2 MeV and 11 MeV above threshold. The total cross section rises from 0.25 to 0.40 μb in this region. The observed energy dependence can be attributed to the strong final state interaction. The angular distribution is nearly isotropic, consistent with S wave production. A measurement of the pd-->3Heπ+π- cross section in the threshold region is also presented. The setup, which is capable of producing 105 tagged η/s with only a few percent background, is used to investigate rare η decays.

  10. Neutron Diffuse Reflectometry of Magnetic Thin Films with a 3He Analyzer (United States)

    Chen, Wangchun; O'Donovan, Kevin; Borchers, Julie


    Polarized neutron reflectometry (PNR) is a powerful probe that characterizes the magnetization depth profile and magnetic domains in magnetic thin films. Although the conventionally used supermirrors are well-matched for specular PNR, they have limited angular acceptance and hence are impractical for complete characterization of the magnetic off-specular scattering where polarization analysis for diffusely reflected neutrons is required. Polarized ^3He gas, produced by optical pumping, can be used to polarize or analyze neutron beams because of the strong spin dependence of the neutron absorption cross section for ^3He. Here we report efficient polarization analysis of diffusely reflected neutrons in a reflectometry geometry using a polarized ^3He analyzer in conjunction with a position-sensitive detector (PSD). We obtained spin-resolved two-dimensional Qx-Qz reciprocal space maps for a patterned array of Co antidots in both the saturated and the demagnetized states. The preliminary results for a patterned amorphous bilayer, Gd40Fe60/ Tb55Fe45, measured with a ^3He analyzer and a PSD will also be discussed. Using the spin exchange optical pumping method we have achieved record high ^3He polarizations of 76% on the neutron beam line where we measured an initial analyzing efficiency of 0.97 and a neutron transmission for the desired spin state of 0.45.

  11. Investigation of diode-laser pumped thulium-doped fluoride lasers; Investigacao de lasers de floureto dopados com tulio e bombeados por diodo-laser

    Energy Technology Data Exchange (ETDEWEB)

    Matos, Paulo Sergio Fabris de


    Tunable lasers emitting around 2.3 mum region are important in many areas, like gas detection, remote sensing and medical applications. Thulium has a large emission spectra around 2.3 mum with demonstrated tuning range of 2.2-2.45 mum using the YLF host. For efficient pump absorption, a high concentration sensitizer like ytterbium can be used. We demonstrate quasi-cw operation of the Yb:Tm:YLF laser, pumped at 960 nm with a 20 W diode bar achieving the highest output power reported so far of 620 mW. Simultaneous pumping of the 2.3 mm Yb:Tm:YLF laser at 685 nm and 960 nm is demonstrated, showing higher slope efficiency than 960 nm alone. Numerical simulations and analytical models show the best ratio of pump power between both wavelengths. (author)

  12. Designing a Broadband Pump for High-Quality Micro-Lasers via Modified Net Radiation Method

    CERN Document Server

    Nechayev, Sergey; Baldo, Marc A; Rotschild, Carmel


    High-quality micro-lasers are key ingredients in non-linear optics, communication, sensing and low-threshold solar-pumped lasers. However, such micro-lasers exhibit negligible absorption of free-space broadband pump light. Recently, this limitation was lifted by cascade energy transfer, in which the absorption and quality factor are modulated with wavelength, enabling non-resonant pumping of high-quality micro-lasers and solar-pumped laser to operate at record low solar concentration. Here, we present a generic theoretical framework for modeling the absorption, emission and energy transfer of incoherent radiation between cascade sensitizer and laser gain media. Our model is based on linear equations of the modified net radiation method and is therefore robust, fast converging and has low complexity. We apply this formalism to compute the optimal parameters of low-threshold solar-pumped lasers. It is revealed that the interplay between the absorption and self-absorption of such lasers defines the optimal pump ...

  13. Comparison of the treatment of vascular lesions with the copper-vapor laser and flashlamp-pumped dye laser (United States)

    Flock, Stephen T.; Waner, Milton; McGrew, Ben; Colvin, G. B.; Montague, Donna


    Vascular lesions such as port-wine stains and telangiectases are sometimes treated with carbon-dioxide lasers, argon lasers or argon-pumped dye lasers; however these lasers are non- specific in their thermal effect on tissues and as a result often cause significant scarring. Recently, evidence has accumulated that the flashlamp-pumped dye (585 nm) and copper- vapor (578 nm) lasers, which produce pulsed light that is efficiently absorbed by hemoglobin, are more selective in coagulating abnormal vascular tissue and as a result give a superior clinical result. It is not yet clear what the most important physical and biological mechanisms are during the light-tissue interaction mediated by these two lasers. The post-treatment sequence of events is different for tissue irradiated by each laser; most significantly, the flashlamp-pumped dye laser causes significant transient purpura, whereas the copper vapor laser causes blanching and eschar formation. The clinical outcome, that is regression of the lesion, is equally successful with either laser although some evidence has accumulated showing that the flashlamp-pumped dye laser is best suited to the treatment of small vessel disease while the copper-vapor laser is better for the treatment of large vessel disease. In this paper, we will discuss our observations of the treatment of vascular lesions on humans with the copper-vapor and flashlamp-pumped dye lasers using empirically derived efficacious treatment parameters. Mathematical models of light and heat propagation and in vivo experiments involving mice ears and rat skin flaps will be used to elucidate what we feel are the important underlying mechanisms of this vascular lesion laser therapy.

  14. A Laser-Diode-Pumped Widely Tunable Single-Longitude-Mode Tm:YAP Laser at Room Temperature

    Institute of Scientific and Technical Information of China (English)

    LI Yu-Feng; JU You-Lun; YAO Bao-Quan; WANG Yue-Zhu; Sergii Ubizskii


    A laser-diode-pumped widely tunable single-longitude-mode Tm:YAP laser in 2μm eye-safe region is built. Continuous tunable range from 1899nm to 2025nm is achieved with the maximum laser output power of 225 m W at 1989nm. In addition, the Tm:YAP laser operating under multimode and single-mode conditions is discussed.

  15. Diode laser pumped solid state laser. Part IV. ; Noise analysis. Handotai laser reiki kotai laser. 4. ; Noise kaiseki

    Energy Technology Data Exchange (ETDEWEB)

    Sakurai, H.; Seno, T.; Tanabe, Y. (Asahi Glass Co. Ltd., Tokyo (Japan))


    Concerning the second harmonic generation(SHG) of diode laser pumped solid state laser using a nonlinear optical material, the researches are carried out to pracitically apply to the optical pickup. Therefore, the reduction of output optical noise has become the important researching subject. The theoretical and experimental analyses of noise generating mechanism were carried out for the system in which Nd;YAG as the laser diode and KTP (KTiOPO {sub 4}) as the nonlinear optical crystal were used. The following findings for the noise generating mechanism could be obtained: The competitive interaction between the polarization modes was dominant noise mechanism in the high frequency range from 1 to 20MHz and the noise could be removed sufficiently by using the QWP(quarter wave plate). On the other hand, the noise observed in the low frequency range from 100 to 200kHz depended on the resonance length, agreed qualitatively with the theoretical analysis of the noise to the competitive longitudinal modes and agreed quantitatively with the noise generating frequency range. 10 refs., 13 figs., 1 tab.

  16. Modeling of static and flowing-gas diode pumped alkali lasers (United States)

    Barmashenko, Boris D.; Auslender, Ilya; Yacoby, Eyal; Waichman, Karol; Sadot, Oren; Rosenwaks, Salman


    Modeling of static and flowing-gas subsonic, transonic and supersonic Cs and K Ti:Sapphire and diode pumped alkali lasers (DPALs) is reported. A simple optical model applied to the static K and Cs lasers shows good agreement between the calculated and measured dependence of the laser power on the incident pump power. The model reproduces the observed threshold pump power in K DPAL which is much higher than that predicted by standard models of the DPAL. Scaling up flowing-gas DPALs to megawatt class power is studied using accurate three-dimensional computational fluid dynamics model, taking into account the effects of temperature rise and losses of alkali atoms due to ionization. Both the maximum achievable power and laser beam quality are estimated for Cs and K lasers. The performance of subsonic and, in particular, supersonic DPALs is compared with that of transonic, where supersonic nozzle and diffuser are spared and high power mechanical pump (needed for recovery of the gas total pressure which strongly drops in the diffuser), is not required for continuous closed cycle operation. For pumping by beams of the same rectangular cross section, comparison between end-pumping and transverse-pumping shows that the output power is not affected by the pump geometry, however, the intensity of the output laser beam in the case of transverse-pumped DPALs is strongly non-uniform in the laser beam cross section resulting in higher brightness and better beam quality in the far field for the end-pumping geometry where the intensity of the output beam is uniform.

  17. Diffractive Combiner of Single-Mode Pump Laser-Diode Beams (United States)

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


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

  18. Efficient fiber-laser-pumped Ho:YLF oscillator and amplifier utilizing the transmitted pump power of the oscillator

    CSIR Research Space (South Africa)

    Strauss, HJ


    Full Text Available In this paper, researchers have demonstrated that a Ho:YLF oscillator and amplifier system can be designed in a compact setup where the pump power from an unpolarized fibre laser utilized efficiently. The system produced more than 20 mJ energy per...

  19. New class of compact diode pumped sub 10 fs lasers for biomedical applications

    DEFF Research Database (Denmark)

    Le, T.; Mueller, A.; Sumpf, B.;


    -laser. In this work we present an alternative method by deploying frequency-doubled IR diodes with good beam qualities to pump fs-lasers. The revolutionary approach allows choosing any pump wavelengths in the green region and avoids complicated relay optics for the diodes. For the first time we show results...... of a diode-pumped 10 fs-laser and how a single diode setup can be integrated into a 30 x 30 cm(2) fs-laser system generating sub 20 fs laser pulses with output power towards half a Watt. This technology paves the way for a new class of very compact and cost-efficient fs-lasers for life science and industrial...... applications....

  20. Method for optical pumping of thin laser media at high average power

    Energy Technology Data Exchange (ETDEWEB)

    Zapata, Luis E. (Livermore, CA); Beach, Raymond J. (Livermore, CA); Honea, Eric C. (Sunol, CA); Payne, Stephen A. (Castro Valley, CA)


    A thin, planar laser material is bonded to a light guide of an index-matched material forming a composite disk. Diode array or other pump light is introduced into the composite disk through the edges of the disk. Pump light trapped within the composite disk depletes as it multi-passes the laser medium before reaching an opposing edge of the disk. The resulting compound optical structure efficiently delivers concentrated pump light and to a laser medium of minimum thickness. The external face of the laser medium is used for cooling. A high performance cooler attached to the external face of the laser medium rejects heat. Laser beam extraction is parallel to the heat flux to minimize optical distortions.

  1. Diode-pumped tunable laser with dual Cri:LiSAF rods

    Institute of Scientific and Technical Information of China (English)

    Xie Guo-Qiang; Wang Tao; Zhu He-Yuan; Qian Lie-Jia


    We propose and demonstrate a simple approach to lower the thermal quenching effect and improve the output power of Cr:LiSAF lasers, which is accomplished by employing two laser rods. The resonator contains two laser rods and is designed by using two "X" folding cavities in cascade. A tunable laser output of ~ 180 mW has been achieved with the pump of single-striped laser diodes. Compared with lasers using single gain rod, the laser with dual rods shows less severe thermal effect and increases the output by more than two times.

  2. Optimal main pulse angle for different preplasma conditions in transient collisionally pumped x-ray lasers. (United States)

    Ursescu, Daniel; Zielbauer, Bernhard; Kuehl, Thomas; Neumayer, Paul; Pert, Geoff


    The effects of the incidence angle of the main pump (MP) pulse in non-normal pumping geometry and the influence of the MP duration are investigated experimentally and theoretically for a transient collisionally pumped (TCE) x-ray laser in Ni-like Zr at 45 degrees and 72 degrees incidence angle on the target. The way they transfer to the x-ray laser output depends on the preplasma conditions, most notably on the average ionization distribution at the arrival of the MP. Moreover, contrary to previous grazing incidence pumping results, it is found that the shortest attainable MP maximizes the output. Modeling of the experimental results is performed with EHYBRID code. The results are important for scaling high repetition-rate non-normal incidence pumped lasers to sub- 10nm wavelengths.

  3. Ultra low-energy switch based on a cavity soliton laser with pump modulation (United States)

    Eslami, M.; Gandomani, S. Z.; Prati, F.; Tajalli, H.; Kheradmand, R.


    We study the effects of pump modulation in a cavity soliton laser consisting of a vertical cavity surface emitting laser with an intra-cavity saturable absorber. We show that a drifting soliton experiences enhanced mobility features by modulating the pump at the resonance frequency, and the effects are even larger below resonance. In particular, pump modulation reduces the rest time of the soliton in the initial stage of the motion and it increases its drift velocity in this regime. Moreover, pump modulation allows a decrease in the switching energy of the soliton to an amount equal to 36 photons. These results indicate that pump modulation is a promising way for the use of a cavity soliton laser as a fast optical buffer and an ultra low-energy optical switch.

  4. Nd: YAG Laser-Pumped Raman-Shifted Methane Laser as an Eye-safe Laser Rangefmder

    Directory of Open Access Journals (Sweden)

    Jai Paul Dudeja


    Full Text Available In this article, a feasibility study of the design and performance of a laser rangefinder emitting at an eye-safe wavelength of 1.54 micron, is reported. It is a Raman-shifted laser where an Nd:YAG laser emitting at a wavelength of 1.06 micron is used as pumping source that is incident on a Raman cell containing methane gas at a very high pressure, rsulting in the Stokes radiation at 1.54 micron. Conversion efficiencies as higb as 40 per cent have been reported so far by some workers and continued efforts are on to increase this value close tothe theoretical Qmits. A comparative performance of this laser, proposed as a futuristic military rangefinder, is studied vis-a-vis commonly used Nd:YAG lasers as well as more recent rangefinders using CO2 lasers. A comparison of this laser emitting at 1.54 micron,with Er : glass laser emitting at the same wavelength, is also discussed.

  5. 1-kilowatt CW all-fiber laser oscillator pumped with wavelength-beam-combined diode stacks. (United States)

    Xiao, Y; Brunet, F; Kanskar, M; Faucher, M; Wetter, A; Holehouse, N


    We have demonstrated a monolithic cladding-pumped ytterbium-doped single all-fiber laser oscillator generating 1 kW of CW signal power at 1080 nm with 71% slope efficiency and near diffraction-limited beam quality. Fiber components were highly integrated on "spliceless" passive fibers to promote laser efficiency and alleviate non-linear effects. The laser was pumped through a 7:1 pump combiner with seven 200-W 91x nm fiber-pigtailed wavelength-beam-combined diode-stack modules. The signal power of such a single all-fiber laser oscillator showed no evidence of roll-over, and the highest output was limited only by available pump power.

  6. Heat generation and thermo-mechanical effect modeling in longitudinally diode-pumped solid state lasers (United States)

    Lakhdari, Fouad; Osmani, Ismahen; Tabet, Saida


    Thermal management in solid state laser is a challenge to the high power laser industry's ability to provide continued improvements in device and system performance. In this work an investigation of heat generation and thermo-mechanical effect in a high-power Nd:YAG and Yb:YAG cylindrical-type solid state laser pumped longitudinally with different power by fibre coupled laser diode is carried out by numerical simulation based on the finite element method (FEM). Impact of the dopant concentration on the power conversion efficiency is included in the simulation. The distribution of the temperature inside the lasing material is resolute according to the thermal conductivity. The thermo-mechanical effect is explored as a function of pump power in order to determine the maximum pumping power allowed to prevent the crystal's fracture. The presented simulations are in broad agreement with analytical solutions; provided that the boundary condition of the pump induced heat generation is accurately modelled.

  7. High Speed Pump-Probe Apparatus for Observation of Transitional Effects in Ultrafast Laser Micromachining Processes

    Directory of Open Access Journals (Sweden)

    Ilya Alexeev


    Full Text Available A pump-probe experimental approach has been shown to be a very efficient tool for the observation and analysis of various laser matter interaction effects. In those setups, synchronized laser pulses are used to create an event (pump and to simultaneously observe it (probe. In general, the physical effects that can be investigated with such an apparatus are restricted by the temporal resolution of the probe pulse and the observation window. The latter can be greatly extended by adjusting the pump-probe time delay under the assumption that the interaction process remains fairly reproducible. Unfortunately, this assumption becomes invalid in the case of high-repetition-rate ultrafast laser material processing, where the irradiation history strongly affects the ongoing interaction process. In this contribution, the authors present an extension of the pump-probe setup that allows to investigate transitional and dynamic effects present during ultrafast laser machining performed at high pulse repetition frequencies.

  8. Effect of absorbed pump power on the quality of output beam from monolithic microchip lasers

    Indian Academy of Sciences (India)

    Pranab K Mukhopadhyay; K Ranganathan; Jogy George; S K Sharma; T P S Nathan


    The dependence of the beam propagation factor (2 parameter) with the absorbed pump power in the case of monolithic microchip laser under face-cooled configuration is extensively studied. Our investigations show that the 2 parameter is related to the absorbed pump power through two parameters ( and ) whose values depend on the laser material properties and laser configuration. We have shown that one parameter arises due to the oscillation of higher order modes in the microchip cavity and the other parameter accounts for the spherical aberration associated with the thermal lens induced by the pump beam. Such dependency of 2 parameter with the absorbed pump power is experimentally verified for a face-cooled monolithic microchip laser based on Nd3+ - doped GdVO4 crystal and the values of and parameters were estimated from the experimentally measured data points.

  9. High-efficiency resonantly pumped 1550-nm fiber-based laser transmitter Project (United States)

    National Aeronautics and Space Administration — nLight proposes the development of high efficiency, high average power 1550-nm laser transmitter system that is based on Er-doped fiber amplifier resonantly pumped...

  10. High energy diode-pumped solid-state laser development at the Central Laser Facility (United States)

    Mason, Paul D.; Banerjee, Saumyabrata; Ertel, Klaus; Phillips, P. Jonathan; Butcher, Thomas; Smith, Jodie; De Vido, Mariastefania; Chekhlov, Oleg; Hernandez-Gomez, Cristina; Edwards, Chris; Collier, John


    In this paper we review the development of high energy, nanosecond pulsed diode-pumped solid state lasers within the Central Laser Facility (CLF) based on cryogenic gas cooled multi-slab ceramic Yb:YAG amplifier technology. To date two 10J-scale systems, the DiPOLE prototype amplifier and an improved DIPOLE10 system, have been developed, and most recently a larger scale system, DiPOLE100, designed to produce 100 J pulses at up to 10 Hz. These systems have demonstrated amplification of 10 ns duration pulses at 1030 nm to energies in excess of 10 J at 10 Hz pulse repetition rate, and over 100 J at 1 Hz, with optical-to-optical conversion efficiencies of up to 27%. We present an overview of the cryo-amplifier concept and compare the design features of these three systems, including details of the amplifier designs, gain media, diode pump lasers and the cryogenic gas cooling systems. The most recent performance results from the three systems are presented along with future plans for high energy DPSSL development within the CLF.

  11. A new LD-pumped single frequency micro-chip green la-ser

    Institute of Scientific and Technical Information of China (English)

    LIN Hai-feng; CHEN Jian-lin; YANG Shang-gong


    A novel LD-pumped single-frequency micro-chip green laser is presented By using the combination of short cavity and Loyt filter formed by Rochon prism and KTP crystal, a stable single frequency green laser is obtained with 60 mW output at 500 mWLD-pump. The optical-to-optical conversion efficiency is about 12%. The optical contact between components of the laser is adopted. This laser has the advantages of a compact structure and a low cost.

  12. High-Power Continuous-Wave Directly-Diode-Pumped Fiber Raman Lasers

    Directory of Open Access Journals (Sweden)

    Tianfu Yao


    Full Text Available We describe novel fiber Raman lasers pumped directly by spectrally combined high power multimode laser diodes at 975 nm and emitting at 1019 nm. With a commercial multimode graded-index fiber, we reached 20 W of laser output power with a record slope efficiency of 80%. With an in-house double-clad fiber, the beam quality improved to M2 = 1.9, albeit with lower output power and slope efficiency due to higher fiber loss. We believe this is the first publication of a fiber Raman laser cladding-pumped directly by diodes.

  13. Pump-probe imaging of laser-induced periodic surface structures after ultrafast irradiation of Si

    Energy Technology Data Exchange (ETDEWEB)

    Murphy, Ryan D. [Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109 (United States); Torralva, Ben [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Adams, David P. [Sandia National Laboratories, Albuquerque, New Mexico 87123 (United States); Yalisove, Steven M. [Department of Materials Science and Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States)


    Ultrafast pump-probe microscopy has been used to investigate laser-induced periodic surface structure (LIPSS) formation on polished Si surfaces. A crater forms on the surface after irradiation by a 150 fs laser pulse, and a second, subsequent pulse forms LIPSS within the crater. Sequentially delayed images show that LIPSS with a periodicity slightly less than the fundamental laser wavelength of 780 nm appear on Si surfaces ∼50 ps after arrival of the second pump laser pulse, well after the onset of melting. LIPSS are observed on the same timescale as material removal, suggesting that their formation involves material ejection.

  14. Pump-probe imaging of laser-induced periodic surface structures after ultrafast irradiation of Si (United States)

    Murphy, Ryan D.; Torralva, Ben; Adams, David P.; Yalisove, Steven M.


    Ultrafast pump-probe microscopy has been used to investigate laser-induced periodic surface structure (LIPSS) formation on polished Si surfaces. A crater forms on the surface after irradiation by a 150 fs laser pulse, and a second, subsequent pulse forms LIPSS within the crater. Sequentially delayed images show that LIPSS with a periodicity slightly less than the fundamental laser wavelength of 780 nm appear on Si surfaces ˜50 ps after arrival of the second pump laser pulse, well after the onset of melting. LIPSS are observed on the same timescale as material removal, suggesting that their formation involves material ejection.

  15. Diode-pumped Nd:GAGG-LBO laser at 531 nm (United States)

    Zou, J.; Chu, H.; Wang, L. R.


    We report a green laser at 531 nm generation by intracavity frequency doubling of a continuous wave (cw) laser operation of a 1062 nm Nd:GAGG laser under in-band diode pumping at 808 nm. A LiB3O5 (LBO) crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation of the laser. At an incident pump power of 18.5 W, as high as 933 mW of cw output power at 531 nm is achieved. The fluctuation of the green output power was better than 3.5% in the given 4 h.

  16. Diode Stack End-Pumped Nd:GdVO4 Continuous Wave Slab Laser

    Institute of Scientific and Technical Information of China (English)

    ZHANG Heng-Li; ZHANG Huai-Jin; LI Dai-Jun; WANG Ji-Yang; SHI Peng; Haas Rüdiger; LI Hong-Xia; JIANG Min-Hua; DU Keming


    @@ We report a diode stack end-pumped Nd:GdVO4 slab laser with a near-diffraction-limited beam. The output power of 45.8 W at 1064nm is obtained under the pumping power of 147W, with the optical-optical conversion efficiency of 31.2%, and the slope efficiency is 39.6%.

  17. Multi-pass 1.9 um Tm:YLF slab laser pump source

    CSIR Research Space (South Africa)

    Strauss, HJ


    Full Text Available A novel multi-pass Tm: YLF laser was demonstrated with an improvement in efficiency, footprint and cost over a two diode stack pumped, single pass system. 100 W of output power from 261 W of incident diode pump power with a slope efficiency of 44...

  18. Microsecond pulsed optical parametric oscillator pumped by a Q-switched fiber laser

    NARCIS (Netherlands)

    Klein, M.E.; Adel, P.; Auerbach, M.; Fallnich, C.; Gross, P.; Boller, Klaus J.


    We report on what is to our knowledge the first optical parametric oscillator (OPO) pumped by microsecond pulses from a wavelength-tunable solid-state laser. The singly resonant OPO (SRO) is based on a periodically poled LiNbO3 crystal and pumped with 2.1-ms-long pulses from an actively Q-switched Y

  19. Lunar ~3He estimations and related parameters analyses

    Institute of Scientific and Technical Information of China (English)


    As a potential nuclear fuel, 3He element is significant for both the solution of impending human energy crisis and the conservation of natural environment. Lunar regolith contains abundant and easily extracted 3He. Based on the analyses of the impact factors of 3He abundance, here we have compared a few key assessment parameters and approaches used in lunar regolith 3He reserve estimation and some representative estimation results, and discussed the issues concerned in 3He abundance variation and 3He reserve estimation. Our studies suggest that in a range of at least meters deep, 3He abundance in lunar regolith is homogeneously distributed and generally does not depend on the depth; lunar regolith has long been in a saturation state of 3He trapped by minerals through chemical bonds, and the temperature fluctuation on the lunar surface exerts little influence on the lattice 3He abundance. In terms of above conclusions and the newest lunar regolith depth data from the microwave brightness temperature retrieval of the "ChangE-1" Lunar Microwave Sounder, a new 3He reserve estimation has been presented.

  20. 5kW GTWave fiber amplifier directly pumped by commercial 976nm laser diodes. (United States)

    Zhan, Huan; Liu, Qinyong; Wang, Yuying; Ke, Weiwei; Ni, Li; Wang, Xiaolong; Peng, Kun; Gao, Cong; Li, Yuwei; Lin, Honghuan; Wang, Jianjun; Jing, Feng; Lin, Aoxiang


    With home-made fiber perform and special fiber drawing & coating technique, a new-type of (3 + 1) GTWave fiber theoretically designed for bi-directional pump method, was successfully fabricated and justified of integrating multi-kW pump energy from commercial 976nm laser diodes. This (3 + 1) GTWave fiber amplifier demonstrated uniform absorption of pump light and easy thermal management characteristics along the whole fiber length. This amplifier is capable of simultaneously aggregating 5.19kW pump power at 976nm and finally generating 5.07kW laser output at 1066.5nm with an optical-to-optical efficiency of 74.5%, the first publically-reported multi-kW GTWave fiber directly pumped with commercial 976nm laser diodes to the best of our knowledge. No power roll-over was found at 5kW level and further power scaling can be expected with more pump power. The results indicate that GTWave fiber is a competitive integrated fiber device to collect enough pump energy from low-cost commercial laser diodes for multi-kW fiber laser development.

  1. High-efficiency Tm-doped yttrium aluminum garnet laser pumped with a wavelength-locked laser diode (United States)

    Huang, H. Z.; Huang, J. H.; Liu, H. G.; Dai, S. T.; Weng, W.; Zheng, H.; Ge, Y.; Li, J. H.; Deng, J.; Yang, X.; Lin, W. X.


    We first demonstrate a high-efficiency composite Tm-doped yttrium aluminum garnet laser end-pumped with a narrow-linewidth laser diode, which was locked at a wavelength of 784.9 nm with volume Bragg gratings. The locked pump wavelength was experimentally determined by the excitation peak, which was also the absorption peak of a 3.5 at.% Tm:YAG crystal around 785 nm, for the improvement of laser efficiency under high-intensity pumping. Under an absorbed pump power of 24.64 W, a maximum output power of 11.12 W at 2018 nm was obtained, corresponding to an optical to optical conversion efficiency of 45.1% and a slope efficiency of 52.4%.

  2. Laser action at 16. mu. by optical pumping of CO/sub 2/ with an HF laser

    Energy Technology Data Exchange (ETDEWEB)

    Kuntsevich, B.F.; Stepanov, B.I.; Trushin, S.A.; Churakov, V.V.


    Calculations are presented on the threshold properties of a CO/sub 2/ laser that is optically pumped by the P/sub 1/(7) line of a HF laser. The dependence on the CO/sub 2/ pressure is considered.(AIP)

  3. Core temperature in super-Gaussian pumped air-clad photonic crystal fiber lasers compared with double-clad fiber lasers

    Indian Academy of Sciences (India)

    P Elahi; H Nadgaran; F Kalantarifard


    In this paper we investigate the core temperature of air-clad photonic crystal fiber (PCF) lasers pumped by a super-Gaussian (SG) source of order four. The results are compared with conventional double-clad fiber (DCF) lasers pumped by the same super-Gaussian and by top-hat pump profiles.

  4. TEM00 mode Nd:YAG solar laser by side-pumping a grooved rod (United States)

    Vistas, Cláudia R.; Liang, Dawei; Almeida, Joana; Guillot, Emmanuel


    A simple TEM00 mode solar laser system with a grooved Nd:YAG rod pumped through a heliostat-parabolic mirror system is reported here. The radiation coupling capacity of a fused silica tube lens was combined with the multipass pumping ability of a 2 V-shaped cavity to provide efficient side-pumping along a 4.0 mm diameter grooved Nd:YAG single-crystal rod. TEM00 mode solar laser power of 3.4 W was measured by adopting an asymmetric large-mode laser resonant cavity. Record TEM00 mode solar laser collection efficiency of 3.4 W/m2and slope efficiency of 1.9% was achieved, which corresponds to 1.8 and 2.4 times more than the previous TEM00 mode Nd:YAG solar laser using the PROMES-CNRS heliostat-parabolic mirror system, respectively.

  5. Performance Limits of Pulse Tube Cryocoolers Using 3HE (United States)

    Kittel, P.


    The enthalpy, entropy, and exergy flows resulting from the real gas effects of 3He in ideal pulse tube cryocoolers are described. The discussion follows a previous description of the real gas effects of 4He in ideal pulse tube cryocoolers and makes use of a recently developed model of the thermophysical properties of 3He. This model is used to describe how the thermodynamic flows are affected by real gas phenomena of 3He and compares these effects to similar effects for 4He. The analysis was done over the pressure range 0.3-2 MPa and temperatures down to 1 K. At 2 MPa there is almost no difference in the cooling power between 3He and 4He. At lower pressures, using 3He is advantageous. There is a 1-2 K reduction in the 3He cooling power vs. temperature curves compared to those for 4He in the 0.3-1 MPa range.

  6. A low timing jitter picosecond microchip laser pumped by pulsed LD (United States)

    Wang, Sha; Wang, Yan-biao; Feng, Guoying; Zhou, Shou-huan


    SESAM passively Q-switched microchip laser is a very promising instrument to replace mode locked lasers to obtain picosecond pulses. The biggest drawback of a passively Q-switched microchip laser is its un-avoided large timing jitter, especially when the pump intensity is low, i.e. at low laser repetition rate range. In order to obtain a low timing jitter passively Q-switched picosecond microchip laser in the whole laser repetition rate range, a 1000 kHz pulsed narrow bandwidth Fiber Bragg Grating (FBG) stablized laser diode was used as the pump source. By tuning the pump intensity, we could control the output laser frequency. In this way, we achieved a very low timing jitter passively Q-switched picosecond laser at 2.13 mW, 111.1 kHz. The relative timing jitter was only 0.0315%, which was around 100 times smaller compared with a cw LD pumped microchip working at hundred kilohertz repetition rate frequency range.

  7. A Polymer Film Dye Laser with Spatially Modulated Emission Controlled by Transversely Distributed Pumping

    Directory of Open Access Journals (Sweden)

    Zurab V. Wardosanidze


    Full Text Available Spatial modulation of laser emission controlled by the structure of excitation light field was demonstrated. A dye doped polymer film as an active medium was sandwiched between two laser mirrors forming a laser cell. The pumping was performed by an interference pattern formed with two mutually coherent beams of the second harmonic of a Q-switched Nd:YAG laser (532 nm and located in the plane of the laser cell. The laser emission was observed normally on the plane of the cell. The cross section of the obtained laser emission was modulated in intensity with an interval between maximums depending on the period of the pumping interference pattern. Thus, the emitted light field qualitatively looks like diffraction from an elementary dynamic hologram, that is, a holographic diffraction grating.

  8. Cryogenic Ho:CaF2 laser pumped by Tm:fiber laser (United States)

    Jelínek, Michal; Kubeček, Václav; Ma, Weiwei; Zhao, Beibei; Jiang, Dapeng; Su, Liangbi


    The laser operation in the pulsed as well as continuous-wave regime of a modified-Bridgeman-grown 0.5 at.% Ho:CaF2 crystal at 83 K pumped by a Tm:fiber laser is reported. The maximum output power was 2.37 W at 2060 nm or 1.3 W at 2110 and 2130 nm. Continuous tuning range over 90 nm from 2030 to 2120 nm was achieved using a birefringent filter. The Ho:CaF2 fundamental spectroscopic properties as absorption and fluorescence spectra at 83 and 293 K are also presented.

  9. Blue Up-Conversion Fibre Laser Pumped by a 1120-nm Raman Fibre Laser

    Institute of Scientific and Technical Information of China (English)

    QIN Guan-Shi; HUANG Sheng-Hong; FENG Yan; SHIRAKAWA A.; MUSHA M.; UEDA Ken-ichi


    @@ A Tm3+-doped ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) fibre up-conversion laser pumped by a 1120-nm Raman fibre laser is demonstrated with blue output power levels up to 116mW. For the output mirror with 80% reflectivity, the slope efficiency is about 15%, the optical-to-optical conversion efficiency is 11%, and the maximum un-saturated output power is 116mW. For 60% reflectivity, the slope efficiency is about 18% and the opticalto-optical conversion efficiency is 12%, whilst the maximum saturated output power is about 80mW due to the existence of photo-degradation effect in Tm3+ doped ZBLAN glass fibre.

  10. A Precision Measurement of Nuclear Muon Capture on $^{3}He$

    CERN Document Server

    Ackerbauer, P; Baturin, V N; Beer, G A; Breunlich, W H; Case, T; Crowe, K M; Daniel, H; Deutsch, J; Govaerts, J; Grigoriev, Yu S; Hartmann, F J; Kammel, P; King, R; Lauss, B; Maev, E M; Markushin, V E; Marton, J; Mühlbauer, M; Petitjean, C; Petitjean, T; Petrov, G E; Prieels, R; Prymas, W; Schott, W; Semenchuk, G G; Smirenin, Yu V; Vorobyov, A A; Voropaev, N I; Wojciechowski, P; Grigoriev, Yu.S.; Petitjean, Th.; Smirenin, Yu.V.


    The muon capture rate in the reaction mu- 3He -> nu + 3H has been measured at PSI using a modular high pressure ionization chamber. The rate corresponding to statistical hyperfine population of the mu-3He atom is (1496.0 +- 4.0) s^-1. This result confirms the PCAC prediction for the pseudoscalar form factors of the 3He-3H system and the nucleon.

  11. Ti : sapphire laser synchronised with femtosecond Yb pump laser via nonlinear pulse coupling in Ti : sapphire active medium (United States)

    Didenko, N. V.; Konyashchenko, A. V.; Konyashchenko, D. A.; Kostryukov, P. V.; Kuritsyn, I. I.; Lutsenko, A. P.; Mavritskiy, A. O.


    A laser system utilising the method of synchronous pumping of a Ti : sapphire laser by a high-power femtosecond Yb3+-doped laser is described. The pulse repetition rate of the Ti : sapphire laser is successfully locked to the repetition rate of the Yb laser for more than 6 hours without the use of any additional electronics. The measured timing jitter is shown to be less than 1 fs. A simple qualitative model addressing the synchronisation mechanism utilising the cross-phase modulation of oscillation and pump pulses within a Ti : sapphire active medium is proposed. Output parameters of the Ti : sapphire laser as functions of its cavity length are discussed in terms of this model.

  12. Basic studies on laser-assisted phacoemulsification using diode-pumped Er:YAG laser (United States)

    Hausladen, Florian; Wurm, Holger; Stock, Karl


    The aim of this study was to determine the potential of a novel diode-pumped Er:YAG laser for phacoemulsification in basic experimental investigations. An appropriate experimental setup was created, including a translation stage for sample movement, a sample holder, a water spray for sample humidification and a surgical microscope with a CCD camera for video documentation. The analysis of the laser cuts and histological sections was done by light microscopy. As samples porcine eye lenses hardened by formalin were used. In ablation experiments with different spot diameters and radiant powers and a constant repetition rate νr = 200 Hz the maximum ablation depths of (4.346 +/- 0.044) mm have reached at (Ø = 480 μm, Φ = 24.15 W) with a maximum extend of thermal damage of (0.165 +/- 0.030) mm. The average ablation efficiency is 0.241 mm3/J. With a spot diameter of 308 μm the maximum ablation depth is (4.238 +/- 0.040) mm at 24.65 W with a mean ablation efficiency of 0.293 mm3/J. The extend of the thermally damaged region is (0.171 +/- 0.024) mm at this laser power. Using a sapphire cylinder with a diameter of 412 μm (length 38.5 mm) in direct tissue contact with water spray for sample humidification the ablation depth reaches (1.017 +/- 0.074) mm at 4.93 W and (1.840 +/- 0.092) mm at 9.87 W with a mean efficiency of 0.261 mm3/J. A thermal damage zone of (0.064 +/-0.024) mm at 9.87 W was measured. Additionally, at this high power, a progressive contamination and destruction of the cylinder end facet was observed. In conclusion, the investigations show that the diode-pumped Er:YAG laser has considerable potential for cataract surgery.

  13. Efficient Diode-Pumped Passively Q-Switched Nd:GdVO4 Lasers

    Institute of Scientific and Technical Information of China (English)

    刘杰; 贾玉磊; 杨济民; 杜鹃; 何京良


    An efficient diode-pumped Nd:GdVO4 laser passively Q-switched by a Cr4+ :YAG has been developed as a saturable absorber. A KTP crystal is used for the extra-cavity second-harmonic generation and a BBO crystal for the sum frequency mixing. The green output power is 172mW at incident pump power of 8 W. The ultraviolet (UV) output power is measured to be 20mW at the same pump power. The peak power of the UV laser is 143 W with the pulse repetition rate of 14 kHz and pulse width of 10 ns.

  14. Recent development on high-power tandem-pumped fiber laser (United States)

    Zhou, Pu; Xiao, Hu; Leng, Jinyong; Zhang, Hanwei; Xu, Jiangmin; Wu, Jian


    High power fiber laser is attracting more and more attention due to its advantage in excellent beam quality, high electricto- optical conversion efficiency and compact system configuration. Power scaling of fiber laser is challenged by the brightness of pump source, nonlinear effect, modal instability and so on. Pumping active fiber by using high-brightness fiber laser instead of common laser diode may be the solution for the brightness limitation. In this paper, we will present the recent development of various kinds of high power fiber laser based on tandem pumping scheme. According to the absorption property of Ytterbium-doped fiber, Thulium-doped fiber and Holmium-doped fiber, we have theoretically studied the fiber lasers that operate at 1018 nm, 1178 nm and 1150 nm, respectively in detail. Consequently, according to the numerical results we have optimized the fiber laser system design, and we have achieved (1) 500 watt level 1018nm Ytterbium-doped fiber laser (2) 100 watt level 1150 nm fiber laser and 100 watt level random fiber laser (3) 30 watt 1178 nm Ytterbium-doped fiber laser, 200 watt-level random fiber laser. All of the above-mentioned are the record power for the corresponded type of fiber laser to the best of our knowledge. By using the high-brightness fiber laser operate at 1018 nm, 1178 nm and 1150 nm that we have developed, we have achieved the following high power fiber laser (1) 3.5 kW 1090 nm Ytterbium-doped fiber amplifier (2) 100 watt level Thulium-doped fiber laser and (3) 50 watt level Holmium -doped fiber laser.

  15. New Electronic-Transition Laser Systems. Part 1. Electron Pumped Systems. Part 2. Chemically Pumped Systems (United States)


    laser development . There has not yet been a demonstration of gain in a visible chemical laser systems, and it appears unlikely that practical lasers of this type will be developed in the near future. Substantial progress has been made

  16. High-repetition-rate femtosecond dye amplifier using a laser-diode-pumped neodymium:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Zysset, B.; LaGasse, M.J.; Fujimoto, J.G.; Kafka, J.D.


    A high-repetition-rate femotosecond dye amplifier is demonstrated using a laser-diode-pumped Q-switched Nd:YAG laser. Amplification of wavelength-tunable 300-fs pulses from a synchronously mode-locked rhodamine dye laser is achieved with a saturated gain of 70 and a small gain of 200 at a repetition rate of 800 Hz. Maximum pulse energies of 40 nJ are obtained, and pulse compression to as short as 30 fs is demonstrated.

  17. Phosphate-core silica-clad Er/Yb-doped optical fiber and cladding pumped laser. (United States)

    Egorova, O N; Semjonov, S L; Velmiskin, V V; Yatsenko, Yu P; Sverchkov, S E; Galagan, B I; Denker, B I; Dianov, E M


    We present a composite optical fiber with a Er/Yb co-doped phosphate-glass core in a silica glass cladding as well as cladding pumped laser. The fabrication process, optical properties, and lasing parameters are described. The slope efficiency under 980 nm cladding pumping reached 39% with respect to the absorbed pump power and 28% with respect to the coupled pump power. Due to high doping level of the phosphate core optimal length was several times shorter than that of silica core fibers.

  18. Low-noise Raman fiber amplifier pumped by semiconductor disk laser. (United States)

    Chamorovskiy, A; Rautiainen, J; Rantamäki, A; Okhotnikov, O G


    A 1.3 µm Raman fiber amplifier pumped by 1.22 µm semiconductor disk laser in co-propagation geometry is demonstrated. Measured relative intensity noise of -148 dB/Hz over frequency range up to 3.5 GHz was measured at 900 mW of pump power. 9 dB gain was achieved with co-propagating pumping geometry with less than 2 dB additional noise induced by amplifier to the signal. Nearly shot-noise-limited operation of semiconductor disk laser combined with the diffraction-limited beam allows for efficient core-pumping of the single-mode fiber Raman amplifiers and represents a highly practical approach which takes full advantage of co-propagating pumping.

  19. High power operation of cladding pumped holmium-doped silica fibre lasers. (United States)

    Hemming, Alexander; Bennetts, Shayne; Simakov, Nikita; Davidson, Alan; Haub, John; Carter, Adrian


    We report the highest power operation of a resonantly cladding-pumped, holmium-doped silica fibre laser. The cladding pumped all-glass fibre utilises a fluorine doped glass layer to provide low loss cladding guidance of the 1.95 µm pump radiation. The operation of both single mode and large-mode area fibre lasers was demonstrated, with up to 140 W of output power achieved. A slope efficiency of 59% versus launched pump power was demonstrated. The free running emission was measured to be 2.12-2.15 µm demonstrating the potential of this architecture to address the long wavelength operation of silica based fibre lasers with high efficiency.


    Directory of Open Access Journals (Sweden)

    P. A. Loiko


    Full Text Available An experimental setup was developed for thermal lensing measurements in the anisotropic diode-pumped laser crystals. The studied crystal is placed into the stable two-mirror laser cavity operating at the fundamental transversal mode. The output beam radius is measured with respect to the pump intensity for different meridional planes (all these planes contain the light propagation direction. These dependencies are fitted using the ABCD matrix method in order to obtain the sensitivity factors showing the change of the optical power of thermal lens due to variation of the pump intensity. The difference of the sensitivity factors for two mutually orthogonal principal meridional planes describes the thermal lens astigmatism degree. By means of this approach, thermal lensing was characterized in the diode-pumped monoclinic Np-cut Nd:KGd(WO42 laser crystal at the wavelength of 1.067 μm for light polarization E || Nm.

  1. Diode-pumped Q-switched Nd{sup 3+} : YAG laser operating in a wide temperature range without thermal stabilisation of pump diodes

    Energy Technology Data Exchange (ETDEWEB)

    Vainshenker, A E; Vilenskiy, A V; Kazakov, A A; Lysoy, B G; Mikhailov, L K; Pashkov, V A [Open Joint-Stock Company ' M.F. Stel' makh Polyus Research and Development Institute' , Moscow (Russian Federation)


    A model sample of a compact low-power-consumption Nd{sup 3+} : YAG laser emitting 20-mJ pulses with a pulse repetition rate up to 20 Hz (in cyclic duty) at a wavelength of 1064 nm is developed and studied. The laser is designed for operating at external temperatures from -40 to +50 deg C. This was achieved by using quasi-end diode pumping without thermal stabilisation of pump diodes. (laser optics 2012)

  2. Frequency-doubled DBR-tapered diode laser for direct pumping of Ti:sapphire lasers generating sub-20 fs pulses. (United States)

    Müller, André; Jensen, Ole Bjarlin; Unterhuber, Angelika; Le, Tuan; Stingl, Andreas; Hasler, Karl-Heinz; Sumpf, Bernd; Erbert, Götz; Andersen, Peter E; Petersen, Paul Michael


    For the first time a single-pass frequency doubled DBR-tapered diode laser suitable for pumping Ti:sapphire lasers generating ultrashort pulses is demonstrated. The maximum output powers achieved when pumping the Ti:sapphire laser are 110 mW (CW) and 82 mW (mode-locked) respectively at 1.2 W of pump power. This corresponds to a reduction in optical conversion efficiencies to 75% of the values achieved with a commercial diode pumped solid-state laser. However, the superior electro-optical efficiency of the diode laser improves the overall efficiency of the Ti:sapphire laser by a factor > 2. The optical spectrum emitted by the Ti:sapphire laser when pumped with our diode laser shows a spectral width of 112 nm (FWHM). Based on autocorrelation measurements, pulse widths of less than 20 fs can therefore be expected.

  3. Nd:YAG solid-state ring laser pumped by a light-emitting diode

    Energy Technology Data Exchange (ETDEWEB)

    Belozerov, S.A.; Kornienko, L.S.; Kravtsov, N.V.; Kuratev, I.I.; Rusakov, S.I.; Stel' makh, M.F.; Shelaev, A.A.; Shelaev, A.I.


    This letter reports lasing in an Nd:YAG solid-state laser (lambda = 1.06 pumped either in pulses or continuously by a light-emitting diode. We report the first experimental results on this laser.(AIP)

  4. Pump spot size dependent lasing threshold in organic semiconductor DFB lasers fabricated via nanograting transfer

    DEFF Research Database (Denmark)

    Liu, Xin; Klinkhammer, Sönke; Wang, Ziyao


    material. This geometrically well-defined structure allows for a systematic investigation of the laser threshold behavior. The laser thresholds for these devices show a strong dependence on the pump spot diameter. This experimental finding is in good qualitative agreement with calculations based on coupled...

  5. Room-temperature diode-pumped Yb:KYF(4) laser. (United States)

    Galzerano, Gianluca; Laporta, Paolo; Sani, Elisa; Bonelli, Lucia; Toncelli, Alessandra; Tonelli, Mauro; Pesatori, Alessandro; Svelto, Cesare


    Continuous-wave laser action has been demonstrated in a diode-pumped Yb:KYF(4) crystal. Crystal growth, spectroscopic measurements, and laser results are presented. A maximum output power of 505 mW, a slope efficiency of 43%, and a continuous wavelength tunability range of 65nm, from 1013 to 1078 nm, have been obtained at room temperature.

  6. Reducing Thermal Effect in End-Diode-Pumped Laser Crystal by Using a Novel Resonator

    Institute of Scientific and Technical Information of China (English)

    YAO Ai-Yun; HOU Wei; LI Hui-Qing; BI Yong; LIN Xue-Chun; GENG Ai-Cong; KONG Yu-Peng; CUI Da-Fu; XU Zu-Yan


    @@ We report a new way, i.e. double-end-pumping, to extend the stability range of a laser resonator, in advantage of making the thermal loading be effectively divided between the ends of the laser crystal to reduce the thermal effect, thus to extend the stability range.

  7. Diode-pumped 1.7-W erbium 3-µm fiber laser

    NARCIS (Netherlands)

    Jackson, S.D.; King, T.A.; Pollnau, M.


    Utilizing lifetime quenching of the Er3+ lower laser level by energy transfer to a Pr3+ co-dopant, 1.7 W output power and 17% slope efficiency are demonstrated from a double-clad diode-pumped 2.7-µm Er3+,Pr3+:ZBLAN fiber laser.

  8. Discrete excitation of mode pulses using a diode-pumped solid-state digital laser

    CSIR Research Space (South Africa)

    Ngcobo, Sandile


    Full Text Available In this paper, we experimentally demonstrate novel method of generating discrete excitation of on-demand Lagaurre-Gaussian (LG) mode pulses, in a diode pumped solid-state digital laser. The digital laser comprises of an intra-cavity spatial light...

  9. Methane-based in situ temperature rise measurement in a diode-pumped rubidium laser. (United States)

    Wang, Rui; Yang, Zining; Wang, Hongyan; Xu, Xiaojun


    We measured active zone temperature rise of an operational diode-pumped rubidium laser non-perturbatively with methane-based near-infrared tunable diode laser spectroscopy (TDLAS). For a Rb+ methane diode-pumped alkali laser (DPAL), the temperature rise was obtained. Especially, the temperature differences (∼10  K) between lasing and un-lasing cases were well identified, which demonstrated a high sensitivity of the method. To our knowledge, this is the first demonstration of extending the methane-based TDLAS method to DPAL study.

  10. High Efficient LD-pumped Nd∶YVO4/ LBO Red Laser

    Institute of Scientific and Technical Information of China (English)

    ZHENG Quan; ZHAO Ling; TAN Huiming


    A design of high efficient LD-pumped Nd∶YVO4/LBO red laser was reported in this paper. For the first time, type-I critical phase-matched LBO was used for 1.342 μm intracavity frequency-doubling to obtain 671 nm red laser. With 760 mW incident pump power, 78 mW TEM00 mode red laser output was obtained, the optical-to-optical conversion up to 10%. Measurements showed the beam divergent angle less than 0.5 mrad, polarization degree more than 100∶1 and power instability in 48 hours less than ±2%.

  11. Passive mode locking of a Nd:KGW laser with hot-band diode pumping (United States)

    Eibna Halim, M. Z.; Talukder, R. C.; Waritanant, T.; Major, A.


    Passive mode locking of a Nd:KGW laser with hot-band diode pumping at 910 nm was demonstrated. A semiconductor saturable absorber mirror was used as a mode locking mechanism. The laser generated 2.4 ps pulses at a repetition rate of ~83.8 MHz. An average output power of 87 mW was obtained at 1067 nm. To the best of our knowledge, this is the first report on passive mode locking of a Nd:KGW laser with low quantum defect pumping which holds great promise for further output power scaling.

  12. Spherical distribution structure of the semiconductor laser diode stack for pumping

    Institute of Scientific and Technical Information of China (English)

    Zhao Tianzhuo; Yu Jin; Liu Yang; Zhang Xue; Ma Yunfeng; Fan Zhongwei


    A semiconductor laser diode stack is used for pumping and 8 semiconductor laser diode arrays of the stack are put on a sphere,and the output of every bar is specially off-axis compressed to realize high coupling efficiency.The output beam of this semiconductor laser diode stack is shaped by a hollow duct to the laser active medium.The efficiency of the hollow light pipe,which is used for semiconductor laser diode stack coupling,is analyzed by geometric optics and ray tracing.Geometric optics analysis diagnoses the reasons for coupling loss and guides the design of the structure.Ray tracing analyzes the relation between the structural parameters and the output characteristics of this pumping system,and guides parameter optimization.Simulation and analysis results show that putting the semiconductor laser diode arrays on a spherical surface can increase coupling efficiency,reduce the optimum duct length and improve the output energy field distribution.

  13. Large aperture discharge-pumped KrF laser for picosecond amplification

    CERN Document Server

    Yuan Xiao; LiuJingRu; Goldhar, J


    A large aperture discharge-pumped KrF laser module with simple spark gaps was developed. The laser beam cross section of 4 cm x 3 cm and the maximum laser output energy of 1.3J in 20ns were obtained at the charging voltage of 30 kV and gas mixtures of [F sub 2] : [Kr] : [Ne] = 0.1 : 2 : 97.9. The gain and absorption coefficients at different gas mixtures were measured with a frequency doubled dye laser pumped by a XeCl laser. Using this laser module as a ps amplifier, the output energy of 140 mJ in 10 ps was obtained

  14. The effect of pulsewidth of pumping pulse on the stability of distributed feedback dye laser (United States)

    Pasandideh, K.; Rahbari, M.; Sadighi Bonabi, R.


    The generation of a single and stable picosecond pulse by distributed feedback dye laser is investigated in this work. The numerical result for the rate equation system that includes the thermal effects in the lasing medium is provided. By applying this model to Rhodamine 6G, it is found that considerable improvement in the stability of the laser can be achieved by pumping the system with narrower laser pulses. The simulation shows that if the dye solution is pumped by sub-200 ps pulse, the laser can be operated in single-pulse output mode with acceptable stability in pulsewidth over a long range of pumping intensity. This result is confirmed by a more complicated model composed of non-averaged Maxwell and rate equations. Even though the thermal effects do not play a significant role in equivalent cavity lifetime, they result in considerable wavelength shift toward the shorter wavelengths.

  15. The progress of nuclear pumped laser in CFBR-Ⅱ reactor

    Institute of Scientific and Technical Information of China (English)

    Chengde Yang(杨成德); Hande Chen(陈涵德); Chun Zheng(郑春); Xiaolin Zhao(赵小林); Huilin Han(韩惠林)


    Development of nuclear pumped lasers (NPL) in the CFBR-Ⅱ reactor is briefly reviewed. The results ofthe two NPL experiments in CFBR-Ⅱ reactor are described. The first one focused on the principle ofnuclear pumped laser, and 4-mW laser output power achieved. The second NPL experiment focused onthe small signal gain and the efficiency of the nuclear pumped He-Ar-Xe gas mixture at 1.73 μm. Themaximum laser power measured to be 45 mW when thermal neutron flux rate is 6.9 × 10 14 cm-2 @ s-1.The small signal gain at 1.73μm by the Rigrod analysis method is to be, and the saturationintensity is fitted to be 36 W/cm2.

  16. A High-Energy, 100 Hz, Picosecond Laser for OPCPA Pumping

    Directory of Open Access Journals (Sweden)

    Hongpeng Su


    Full Text Available A high-energy diode-pumped picosecond laser system centered at 1064 nm for optical parametric chirped pulse amplifier (OPCPA pumping was demonstrated. The laser system was based on a master oscillator power amplifier configuration, which contained an Nd:YVO4 mode-locked seed laser, an LD-pumped Nd:YAG regenerative amplifier, and two double-pass amplifiers. A reflecting volume Bragg grating with a 0.1 nm reflective bandwidth was used in the regenerative amplifier for spectrum narrowing and pulse broadening to suit the pulse duration of the optical parametric amplifier (OPA process. Laser pulses with an energy of 316.5 mJ and a pulse duration of 50 ps were obtained at a 100 Hz repetition rate. A top-hat beam distribution and a 0.53% energy stability (RMS were achieved in this system.

  17. Active mode-locking via pump modulation in a Tm-doped fiber laser

    Directory of Open Access Journals (Sweden)

    Yu Wang


    Full Text Available We propose and experimentally realize a new class of actively mode-locking technique using pump modulation for rare-earth doped fiber lasers. A Tm-doped fiber laser at 2 μm is mode-locked using the proposed active mode-locking via pump modulation technique. Low-threshold continuous-wave mode-locking is achieved with a transform-limited pulse width of 4.4 ps, a spectral bandwidth of 0.9 nm, and a repetition rate of 12.9 MHz. Second-harmonic mode-locking is also demonstrated by simply driving the pump current at an appropriate frequency. More importantly, we believe that this technique can be applied to mode-lock other rare-earth doped fiber laser systems such as erbium- and ytterbium-doped fiber lasers.

  18. LD-pumped passively Q-switched red laser at 660 nm

    Institute of Scientific and Technical Information of China (English)

    Qinghua Xue(薛庆华); Quan Zheng(郑权); Yikun Bu(卜轶坤); Longsheng Qian(钱龙生)


    A laser diode (LD) pumped Nd:YAG red pulse laser at 660 nm was presented by V:YAG passively Qswitching and LBO intracavity frequency doubling. With 1.6-W incident pump power, average output power of 46-mW, pulse duration (FWHM) of 23.3 ns, pulse repetition rate of 21.6 kHz, peak power of 91.4 W, and single pulse energy of 2.13μJ were obtained. The beam quality factor M2 was less than 1.2. The fluctuations of pulse energy and repetition rate were less than 3% in 4 hours. The pulsed laser at 660 nm is expected to be used as the pump source of Cr3+:doped crystal to obtain the gain-switched tunable laser.

  19. Ions Preheated in 3He-Rich Solar Particle Events

    Institute of Scientific and Technical Information of China (English)



    A wave-particle resonance absorption model in the two-ion plasma is suggested in explanation to the coronal ions preheating in 3He-rich solar particle events. It is found that 3He and Fe ions are preferably preheated by the ion-ion hybrid waves at their fundamental and second harmonic ion cyclotron frequencies, respectively.

  20. High-power diode-pumped AlGaAs surface-emitting laser. (United States)

    Holm, M A; Burns, D; Cusumano, P; Ferguson, A I; Dawson, M D


    We report the development and characterization of an efficient diode-pumped surface-emitting semiconductor laser operating at approximately 870 nm. By using a semiconductor Bragg reflector stack/multiple GaAs quantum well structure, mounted within a conventional laser cavity, we achieved single transverse mode laser output powers of 153 mW. Self-tuning over a 15-nm spectral range has been obtained.

  1. Synchronous pumping of picosecond dye laser using high efficiency second harmonic generation from optical fibres (United States)

    Lawandy, N. M.; Bernardin, J. P.; Macdonald, R. L.; Demouchy, G.


    The stable operation of a mode-locked dye laser synchronously pumped by the second harmonic of an Nd:YAG laser produced in an Nd codoped germanosilicate optical fiber is reported. The optical fiber preparation technique, which results in a second harmonic conversion efficiency of 2 percent, is described. This optical fiber SHG conversion efficiency is the highest reported to date using a continuous-wave mode-locked laser.

  2. Nanoimprinted organic semiconductor laser pumped by a light-emitting diode. (United States)

    Tsiminis, Georgios; Wang, Yue; Kanibolotsky, Alexander L; Inigo, Anto R; Skabara, Peter J; Samuel, Ifor D W; Turnbull, Graham A


    An organic semiconductor laser, simply fabricated by UV-nanoimprint lithography (UV-NIL), that is pumped with a pulsed InGaN LED is demonstrated. Molecular weight optimization of the polymer gain medium on a nanoimprinted polymer distributed feedback resonator enables the lowest reported UV-NIL laser threshold density of 770 W cm(-2) , establishing the potential for scalable organic laser fabrication compatible with mass-produced LEDs.

  3. Research on fission fragment excitation of gases and nuclear pumping of lasers (United States)

    Schneider, R. T.; Davie, R. N.; Davis, J. F.; Fuller, J. L.; Paternoster, R. R.; Shipman, G. R.; Sterritt, D. E.; Helmick, H. H.


    Experimental investigations of fission fragment excited gases are reported along with a theoretical analysis of population inversions in fission fragment excited helium. Other studies reported include: nuclear augmentation of gas lasers, direct nuclear pumping of a helium-xenon laser, measurements of a repetitively pulsed high-power CO2 laser, thermodynamic properties of UF6 and UF6/He mixtures, and nuclear waste disposal utilizing a gaseous core reactor.

  4. Effects of Plasma Formation on the Cesium Diode (DPAL) and Excimer (XPAL) Pumped Alkali Laser (United States)

    Markosyan, Aram H.; Kushner, Mark J.


    Diode pumped alkali lasers (DPALs) and excimer pumped alkali lasers (XPALs) are being investigated as a means to convert optical pumps having poor optical quality to laser radiation having high optical quality. DPALs sustained in Cs vapor are pumped on the D2(852.35 nm), Cs(62S1/2) --> Cs(62P3/2) , transition and lase on the D1(894.59 nm) transition, Cs(62P1/2) --> Cs(62S1/2) . Collisional mixing (spin orbit relaxation) of the Cs(62P3/2) and Cs(62P1/2) levels is a key part of this three-level (in fact, a quasi-two-level) laser scheme. In the five-level XPAL pumping scheme, the CsAr(B2Σ1/ 2 +) state is optically pumped by 836.7 nm pulses, which later dissociates and produces Cs(62P3/2) . As in DPAL, a collisional relaxant transfers the population of Cs(62P3/2) to Cs(62P1/2) , which enables lasing on D1 transition. A first principals global computer model has been developed for both systems to investigate the effects of plasma formation on the laser performance. Argon is used as a buffer gas and nitrogen or ethane are used as a collisional relaxant at total pressure of 600 Torr at temperatures of 350-450 K, which produces vapor pressures of Cs of systems, a plasma formation in excess of 1014 - 1016cm-3 occurs, which potentially reduces laser output power by electron collisional mixing of upper and lower laser levels. Work supported by DoD High Energy Laser Multidisc, Res. Initiative.

  5. Short-pulse generation in a diode-end-pumped solid-state laser

    CSIR Research Space (South Africa)

    Ngcobo, S


    Full Text Available in the picosecond region with a maximum average output power of 2.8W. Passive modelocking of the Nd:YVO4 laser has been demonstrated using a semiconductor saturable absorber mirror (SESAM). THEORETICAL ANALYSIS Ultra-fast solid state lasers are a key component... theoretical PQSML,th of 2.08W. Short-Pulse Generation in a Diode-End-Pumped Solid-State Laser S. Ngcobo1,2, C. Bollig1 and H. Von Bergmann2 1CSIR National Laser Centre, PO Box 395, Pretoria, 0001, South Africa 2Laser Research Center, University...

  6. Room temperature CW and QCW operation of Ho:CaF2 laser pumped by Tm:fiber laser (United States)

    Jelínek, Michal; Cvrček, Jan; Kubeček, Václav; Zhao, Beibei; Ma, Weiwei; Jiang, Dapeng; Su, Liangbi


    Laser radiation in the wavelength range around 2 μm is required for its specific properties - it is very suitable for medical applications, remote sensing, or pumping of optical parametric oscillators to generate ultrafast pulses in the mid-IR region further exploited in nonlinear optics. Crystals as YLF, YAG, LLF, and GdVO4 doped by holmium were already investigated and found suitable for the tunable laser generation around 2.1 mμ. Only a few works are devoted to the laser operation of holmium-doped fluorides as CaF2. In this work, pulsed and continuous-wave laser operation of a modified- Bridgman-grown Ho:CaF2 active crystal at room temperature is reported. A commercial 50 W 1940 nm Tm-fiber laser was used to pump a laser oscillator based on a novel 10 mm long 0.5 at.% Ho:CaF2 active crystal placed in the Peltiercooled holder. In the pulsed regime (10 ms, 10 Hz), the laser slope efficiency of 53 % with respect to the absorbed pump power was achieved. The laser generated at the central wavelength of 2085 nm with the maximum mean output power of 365 mW corresponding to the power amplitude of 3.65 W. In the continuous wave regime, the maximum output power was 1.11 W with the slope efficiency of 41 % with respect to the absorbed pump power. To our best knowledge this is the first demonstration of this laser active material operating in the CW regime at room temperature. The tuning range over 60 nm from 2034 to 2094 nm was achieved using a birefringent filter showing the possibility to develop a mode-locked laser system generating pulses in the sub-picosecond range.

  7. The Map of 3He Abundance for the Moon Nearside (United States)

    Kaydash, V. G.; Shkuratov, Yu. G.; Starukhina, L. V.


    In [1] strong correlation between 3He content in the lunar soils and the product of the soil maturity Is/FeO upon the content of TiO2 has been presented. Using this correlation we mapped the abundance of 3He for the nearside of the Moon. For this purpose the maps [2] of the maturity degree Is/FeO and abundance of titanium in the regolith of visible hemisphere were taken. The greatest 3He abundance is predicted for the west part of mare Serenitatis (16-20 ppb) associated with ilmenite basalts areas. The lowest 3He (1-5 ppb) is characteristic of the north and south highlands. As 3He is implanted by solar wind, the variation of its average normal flux with latitude and longitude of a lunar site could affect the 3He abundance. If so, 3He content near the poles should be less than that in equatorial zones. However, 3He content is controlled by degassing rates, which is proved by great difference between the abundance ratios of the gases in solar wind and in lunar soils [3]. Moreover, lower temperature in polar regions prevent degassing so effectively that even higher 3He content can be predicted there. As a first approximation we did not take the latitude and longitude dependence of 3He abundance into account. Refs.: [1] Taylor L.A. Engr., constr., & Oper. In Space IV, Proc. of Space'94, 678. [2] Shkuratov Yu.G. et al. 1999. Icarus, 137, 222-234. [3] Haskin L., Warren P. Lunar chemistry. Lunar sourcebook. /Eds. Heiken G. H. et al.. N. Y., 1991. 357-474.

  8. Improved performance of high average power semiconductor arrays for applications in diode pumped solid state lasers

    Energy Technology Data Exchange (ETDEWEB)

    Beach, R.; Emanuel, M.; Benett, W.; Freitas, B.; Ciarlo, D.; Carlson, N.; Sutton, S.; Skidmore, J.; Solarz, R.


    The average power performance capability of semiconductor diode laser arrays has improved dramatically over the past several years. These performance improvements, combined with cost reductions pursued by LLNL and others in the fabrication and packaging of diode lasers, have continued to reduce the price per average watt of laser diode radiation. Presently, we are at the point where the manufacturers of commercial high average power solid state laser systems used in material processing applications can now seriously consider the replacement of their flashlamp pumps with laser diode pump sources. Additionally, a low cost technique developed and demonstrated at LLNL for optically conditioning the output radiation of diode laser arrays has enabled a new and scalable average power diode-end-pumping architecture that can be simply implemented in diode pumped solid state laser systems (DPSSL`s). This development allows the high average power DPSSL designer to look beyond the Nd ion for the first time. Along with high average power DPSSL`s which are appropriate for material processing applications, low and intermediate average power DPSSL`s are now realizable at low enough costs to be attractive for use in many medical, electronic, and lithographic applications.

  9. Modelling the effect of 3He in direct drive capsule implosions (United States)

    Garbett, W. J.; Horsfield, C. J.; Herrmann, H. W.; Langenbrunner, J. R.; Cooley, J. H.; Wilson, D. C.; Evans, S. C.; Sedillo, T. J.; Rubery, M. S.; Drew, D.; Mack, J. M.; Young, C. S.; Kyrala, G. A.; Frenje, J.; Glebov, V. Yu


    D3He fuels are often used in ICF implosion experiments, either as a surrogate for DT to restrict the output neutron yield, or to produce protons for use in diagnosis of core conditions. Recent experiments have suggested that capsules filled with D3He do not behave as expected, but that both proton and neutron yields are anomalously degraded relative to the pure D2 case. We have performed direct drive implosion experiments using the Omega laser to examine the effect of 3He on DT-filled glass capsules. The use of DT fuel allows reaction history measurements to be obtained using the Gas Cherenkov diagnostic (GCD). It was hoped that the detailed information provided by GCD measurements would complement existing measurements to constrain modelling. We present recent modelling and analysis of the experiments using radiation-hydrocode simulations, and explore some of the hypotheses proposed to explain the results.

  10. Experiment Research on a Highly Stable LD-pumped Solid State Laser

    Institute of Scientific and Technical Information of China (English)

    YAN Ping; HE Bin; WEI Guanghui


    In high power laser systems, the stability of the seed laser is vitally important. This paper presents the work on the design and manufacture of a highly stable LD pumped solid state seed laser which has the advantages of being all solid state, compact, easy to manufacture and low cost. The laser was composed of two parts. One was an LD pumped 0.5 mm thin Nd: YLF laser system in which the instability was around±6% (3σ). The other was a close-looped laser power control system using external cavity power feedback. Using an electro-optic modulator, a 1×2 optical fiber splitter and a signal processing circuit, we successfully realized the highly stable LD pumped Nd: YLF laser in which the instability of laser output power was lower than±0.2 %/hour (3σ). A digital PID (Proportion, Integration and Differentiation) control method was used with a control frequency of 40 kHz. The 3 mW of highly stable laser power through the optical fiber was obtained.

  11. Investigation of pre-pulse pumping laser for preserving temporal waveform of stimulated Raman scattering (United States)

    Chen, Junchi; Su, Hongpeng; Peng, Yujie; Guo, Xiaoyang; Wang, Zhanshan; Leng, Yuxin


    A modified polarized beam combination technique is proposed for preserving the temporal waveforms of stimulated Raman scattering. 1064 nm pre-pulse pumping lasers prior to the main pumping laser with a delay time are generated and injected into a Ba(NO3)2 Raman medium to excite the crystal firstly. The influences of pre-pulse lasers with various energy levels on the temporal shapes of Raman lasers are investigated, and it is demonstrated that the temporal waveforms of the Raman laser are distorted once the energies of the pre-pulse are below and above the required energy for preserving the temporal shapes of Stokes radiation. It is also discovered that the temporal shape of the 1197 nm Raman laser cannot be perfectly preserved if the energy of the 1064 nm main laser is too low or the relative delay time is too large. Moreover, the optical conversion efficiency and Stokes laser energy obtained under pumping lasers with single and double intensity peaks are compared.

  12. Efficient quasi-three-level Nd:YAG laser at 946 nm pumped by a tunable external cavity tapered diode laser

    DEFF Research Database (Denmark)

    Cheng, Haynes Pak Hay; Jensen, Ole Bjarlin; Tidemand-Lichtenberg, Peter;


    Using a tunable external cavity tapered diode laser (ECDL) pumped quasi-three-level Nd:YAG laser, a fivefold reduction in threshold and twofold increase in slope efficiency is demonstrated when compared to a traditional broad area diode laser pump source. A TEM00 power of 800 mW with 65% slope...... efficiency is obtained, the highest reported TEM00 power from any 946 nm Nd:YAG laser pumped by a single emitter diode laser pump source. A quantum efficiency of 0.85 has been estimated from experimental data using a simple quasi-three-level model. The reported value is in good agreement with published...... values, suggesting that the model is adequate. Improvement of the 946 nm laser due to the ECDL's narrow spectrum proves to be less significant when compared to its spatial quality, inferring a broad spectrum tapered diode laser pump source may be most practical. Experimental confirmation of such setup...


    Directory of Open Access Journals (Sweden)

    D. A. Arkhipov


    Full Text Available Subject of Research. Thermophysical and optical techniques of parameter regulation for diode pumped solid-state laser are studied as applied to space laser communication and laser ranging lines. Methods. The investigations are carried out on the base of the original design of diode pumped solid-state laser module that includes the following: Nd:YAG slab element, diode pumped by 400W QCW produced by NORTHROP GRUMMAN; two-pass unstable resonator with rotation of the laser beam aperture about its axis through 1800; the output mirror of the resonator with a variable reflection coefficient; hyperthermal conductive plates for thermal stabilization of the laser diode generation modes. The presence of thermal conductive plates excludes conventional running water systems applied as cooling systems for solid-state laser components. The diodes temperature stabilization is achieved by applying the algorithm of pulse-width modulation of power of auxiliary electric heaters. To compensate for non-stationary thermal distortions of the slab refractive index, the laser resonator scheme comprises a prism reflector with an apex angle of 1200. Narrow sides of the prism are covered with reflective coating, and its wide side is sprayed with antireflection coating. The beam aperture is turned around its axis through 1800 because of triple reflection of the beam inside the prism. The turning procedure leads to compensating for the output beam phase distortions in view of symmetric character of the aberrations of slab refractive index. To suppress parasitic oscillations inside the slab, dielectric coatings of wide sides of the slab are used. Main Results. We have demonstrated theoretically and experimentally that the usage of hyperthermal conductive plates together with the algorithm of pulse-width modulation provides stabilizing of the diode substrate temperature accurate within ± 0.1 °С and smoothing the temperature distribution along the plate surface accurate

  14. Tm:GGAG crystal for 2μm tunable diode-pumped laser (United States)

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


    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.

  15. Single-mode, All-Solid-State Nd:YAG Laser Pumped UV Converter (United States)

    Prasad, Narasimha S.; Armstrong, Darrell, J.; Edwards, William C.; Singh, Upendra N.


    In this paper, the status of a high-energy, all solid-state Nd:YAG laser pumped nonlinear optics based UV converter development is discussed. The high-energy UV transmitter technology is being developed for ozone sensing applications from space based platforms using differential lidar technique. The goal is to generate greater than 200 mJ/pulse with 10-50 Hz PRF at wavelengths of 308 nm and 320 nm. A diode-pumped, all-solid-state and single longitudinal mode Nd:YAG laser designed to provide conductively cooled operation at 1064 nm has been built and tested. Currently, this pump laser provides an output pulse energy of >1 J/pulse at 50 Hz PRF and a pulsewidth of 22 ns with an electrical-to-optical system efficiency of greater than 7% and a M(sup 2) value of <2. The single frequency UV converter arrangement basically consists of an IR Optical Parametric Oscillator (OPO) and a Sum Frequency Generator (SFG) setups that are pumped by 532 nm wavelength obtained via Second Harmonic Generation (SHG). In this paper, the operation of an inter cavity SFG with CW laser seeding scheme generating 320 nm wavelength is presented. Efforts are underway to improve conversion efficiency of this mJ class UV converter by modifying the spatial beam profile of the pump laser.

  16. Plasma Formation During Operation of a Diode Pumped Alkali Laser (DPAL) in Cs (United States)

    Babaeva, Natalia Yu.; Zatsarinny, Oleg; Bartschat, Klaus; Kushner, Mark J.


    Diode pumped Alkali Lasers (DPALs) produce laser action on the resonant lines of alkali atoms. Diode lasers resonantly pump the 2P3/2 state of the alkali atom which is collisionally relaxed to the 2P3/2 state which then lases to the ground state 2S1/2. The low optical quality of high power semiconductor diode lasers is converted into high optical quality laser radiation from the alkali vapor. The Cs DPAL system using Ar/Cs/C2H6 mixtures has shown promising results. (C2H6 is the collisional relaxant.) In other studies, resonant excitation of alkali vapor by low power lasers has been used to produce highly ionized channels, initiated through associative ionization and superelastic electron heating. The issue then arises if plasma formation occurs during DPAL by similar mechanisms which would be detrimental to laser performance. In this paper, we report on results from a computational study of a DPAL using Cs vapor. The global model addresses quasi-cw pumping of the Cs(2P3/2) state by laser diodes, and includes a full accounting of the resulting electron kinetics. To enable this study, the B-spline R-matrix (BSR) with pseudostates method was employed to calculate electron impact cross sections for Cs. We found that for pump rates of many to 10 kW/cm2, plasma densities approaching 1013 cm-3 occur during laser oscillation with higher values in the absence of laser oscillation. Supported by DoD High Energy Laser Mult. Res. Initiative and NSF.

  17. Zeeman Relaxation of Cold Atomic Iron and Nickel in Collisions with 3He

    CERN Document Server

    Johnson, Cort; Brahms, Nathan; Doyle, John M; Kleppner, Daniel; Greytak, Thomas J


    We have measured the ratio of the diffusion cross-section to the angular momentum reorientation cross-section in the colliding Fe-3He and Ni-3He systems. Nickel (Ni) and iron (Fe) atoms are introduced via laser ablation into a cryogenically cooled experimental cell containing cold (< 1 K) 3He buffer gas. Elastic collisions rapidly cool the translational temperature of the ablated atoms to the helium temperature. The cross-section ratio is extracted by measuring the decays of the atomic Zeeman sublevels. For our experimental conditions, thermal energy is comparable to the Zeeman splitting. As a result, thermal excitations between Zeeman sublevels significantly impact the observed decay. To determine the cross-section ratio accurately, we introduce a model of Zeeman state dynamics that includes thermal excitations. We find the cross-section ratio for Ni-3He = 5 x 10^3 and Fe-3He <= 3 x 10^3 at 0.75 K in a 0.8 T magnetic field. These measurements are interpreted in the context of submerged shell suppressio...

  18. 1.3 µm Raman-bismuth fiber amplifier pumped by semiconductor disk laser. (United States)

    Chamorovskiy, A; Rautiainen, J; Rantamäki, A; Golant, K M; Okhotnikov, O G


    A hybrid Raman-bismuth fiber amplifier pumped in co-propagation configuration by a single 1.22 µm semiconductor disk laser is presented. The unique attribute of this dual-gain system is that both amplifiers require the pump source with the same wavelength because pump-Stokes spectral shift in 1.3 µm Raman amplifier and pump-gain bandwidth separation in 1.3 µm bismuth fiber amplifier have the same value. Residual pump power at the output of Raman amplifier in this scheme is efficiently consumed by bismuth-doped fiber thus increasing the overall conversion efficiency. The small-signal gain of 18 dB at 1.3 W of pump power has been achieved for hybrid scheme which is by 9 dB higher as compared with isolated Raman amplifier without bismuth fiber. Low noise performance of pump semiconductor disk laser with RIN of -150 dB/Hz combined with nearly diffraction-limited beam quality and Watt-level output powers allows for efficient core-pumping of a single-mode fiber amplifier systems and opens up new opportunities for amplification in O-band spectral range.

  19. Novel Single-Frequency Diode Pumped Solid-State Lasers and Their Applications in Laser Ranging and Velocimetry

    Institute of Scientific and Technical Information of China (English)

    杨苏辉; 吴克瑛; 魏光辉


    Two models of laser diode pumped unidirectional single-frequency ring lasers with maximum single-frequency output powers of 1 W and 780mW are investigated. The statistical linewidth of the free-run laser is measured to be 2.1 kHz within 5μs by using a single-mode fibre link. We use the monolithic laser to measure the angular speed of a spinning motor and simulate a linearly frequency modulated continuous-wave ladar system in the laboratory.

  20. 885-nm Pumped Ceramic Nd:YAG Master Oscillator Power Amplifier Laser System (United States)

    Yu, Anthony


    The performance of a traditional diode pumped solid-state laser that is typically pumped with 808-nm laser diode array (LDA) and crystalline Nd:YAG was improved by using 885-nm LDAs and ceramic Nd:YAG. The advantage is lower quantum defect, which will improve the thermal loading on laser gain medium, resulting in a higher-performance laser. The use of ceramic Nd:YAG allows a higher Nd dopant level that will make up the lower absorption at the 885-nm wavelength on Nd:YAG. When compared to traditional 808-nm pump, 885-nm diodes will have 30% less thermal load (or wasted heat) and will thus see a similar percentage improvement in the overall laser efficiency. In order to provide a more efficient laser system for future flight missions that require the use of low-repetition- rate (systems are numerous. The epitaxial structures of these 885-nm diodes are aluminum-free. There is a significant reduction in the thermal load generated from the Stokes shift or quantum defects. A Stokes shift is the energetic difference between the pump and laser photons. Pumping at a wavelength band closer to the lasing wavelength can reduce the thermal load by .30% compared to traditional pumping at 808 nm, and increase the optical- to-optical efficiency by the same factor. The slope efficiency is expected to increase with a reduction in the thermal load. The typical crystalline Nd:YAG can be difficult to produce with doping level >1% Nd. To make certain that the absorption at 885 nm is on the same par as the 808-nm diode, the Nd:YAG material needs to be doped with higher concentration of Nd. Ceramic Nd:YAG is the only material that can be tailored to specific needs.

  1. Cryogenic nanosecond and picosecond high average and peak power(HAPP) pump lasers for ultrafast applications

    Institute of Scientific and Technical Information of China (English)

    David C.Brown; Sten Tornegrd; Joseph Kolis


    Using cryogenic laser technology, it is now possible to design and demonstrate lasers that have concomitant high average and peak powers, with near-diffraction-limited beam quality. We refer to these new laser systems as HAPP lasers. In this paper, we review important laser crystal materials properties at cryogenic temperature, with an emphasis on Yb lasers, and discuss the important design considerations, including the laser-induced damage threshold, nonlinear effects and thermal effects. A comprehensive model is presented to describe diode pulsed pumping with arbitrary duration and repetition rate, and is used with the Frantz–Nodvik equation to describe, to first order, the performance of HAPP laser systems. A computer code with representative results is also described.

  2. Solar Source Regions of Energetic 3He Emission (United States)

    Mason, G. M.; Nitta, N. V.; Cohen, C. M.; Wiedenbeck, M. E.


    One of the surprising observations from the ACE mission has been the detection of energetic 3He emission occurring over multi-day periods. Previously observations of solar energetic 3He had detected short-lived "impulsive" energetic particle events which were associated with type III bursts and energetic electrons. The ACE observations were able to detect 3He at very low levels (<1% of 4He compared to ~10% in most earlier work) and this showed that the impulsive events often occurred during seemingly continuous multi-day periods of 3He emission. During solar active periods, 3He was present at 1 AU the majority of the time, giving evidence for either semi-continuous processes or else unresolved multiple small injections. The obvious injections during such periods were strongly associated with jet activity By adding STEREO and SDO observations we are seeking to extend the observational picture for these events. First, by following single 3He emitting regions from STEREO-B to ACE to STEREO-A we seek to examine for how long the 3He emission can continue, since any single spacecraft can be magnetically connected to a single region for only a few days and ACE often sees emission periods of that length. Second, by using SDO-AIA we seek to probe further the properties of the emitting regions to see if the previously reported association with jets is seen in events which we can now observe with greater resolution, sensitivity, and cadence than previously possible.

  3. Diode-pumped Q-switched Nd:YLF laser at 1313 nm (United States)

    Xu, Shan; Gao, Shufang; Zheng, Chunyan


    In this letter, we describe the operation of an end-pumped acousto-optic Q-switched Nd:YLF laser. According to the theoretical analysis and calculation for Nd:YLF crystal, the thermal focal length of σ-polarized laser is positive in plane-parallel resonator, while that of π-polarized laser is negative. Hence laser operation at σ-polarized 1313 nm should be stable in plane-parallel cavity. When absorbed pump power is 12.45 W and the pulse repetition frequency is 10 kHz, 3.1 W output laser at 1313 nm is achieved. As a result, the optical-optical conversion efficiency is 25.4 % and slope efficiency is 31.2 %, respectively.

  4. Dynamics of Efficiency Change by Temperature in Diode Pumped Nd:YAG Heat Capacity Laser

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Jun; TANG Bing; SHU Xiao-Jian


    We investigate the influence of temperature on the efficiency of diode pumped Nd:YAG heat capacity laser is studied. It is shown that the efficiency of such a laser system is greatly reduced at higher temperature. This bad behaviour is mainly caused by the doped-ion redistribution among various Stark levels of the ground state, and by a thermal equilibrium between the upper laser level and the pump level. Meanwhile, the thermal excitations from the ground state to the lower laser level also play a role. We derive a model to describe those effects, with the considerations of emission spectrum of laser diodes, the subtle Stark structures and the linewidth of absorption and of simulated-emission.

  5. Lasing of ambient air with microjoule pulse energy pumped by a multi terawatt IR femtosecond laser

    CERN Document Server

    Point, Guillaume; Brelet, Yohann; Mitryukovskiy, Sergey; Ding, Pengji; Houard, Aurélien; Mysyrowicz, André


    We report on the lasing action of atmospheric air pumped by an 800 nm femtosecond laser pulse with peak power up to 4 TW. Lasing emission at 428 nm increases rapidly over a small range of pump laser power, followed by saturation above ~ 1.5 TW. The maximum lasing pulse energy is measured to be 2.6 uJ corresponding to an emission power in the MW range, while a maximum conversion efficiency of is measured at moderate pump pulse energy. The optical gain inside the filament plasma is estimated to be excess of 0.7/cm. The lasing emission shows a doughnut profile, reflecting the spatial distribution of the pump-generated white-light continuum that acts as a seed for the lasing. We attribute the pronounced saturation to the defocusing of the seed in the plasma amplifying region and to the saturation of the seed intensity.

  6. Manipulating coherence resonance in a quantum dot semiconductor laser via electrical pumping. (United States)

    Otto, Christian; Lingnau, Benjamin; Schöll, Eckehard; Lüdge, Kathy


    Excitability and coherence resonance are studied in a semiconductor quantum dot laser under short optical self-feedback. For low pump levels, these are observed close to a homoclinic bifurcation, which is in correspondence with earlier observations in quantum well lasers. However, for high pump levels, we find excitability close to a boundary crisis of a chaotic attractor. We demonstrate that in contrast to the homoclinic bifurcation the crisis and thus the excitable regime is highly sensitive to the pump current. The excitability threshold increases with the pump current, which permits to adjust the sensitivity of the excitable unit to noise as well as to shift the optimal noise strength, at which maximum coherence is observed. The shift adds up to more than one order of magnitude, which strongly facilitates experimental realizations.

  7. Stochastic resonance for signal-modulated pump noise in a single-mode laser

    Institute of Scientific and Technical Information of China (English)

    Liangying Zhang; Li Cao; Fahui Zhu


    By adopting the gain-noise model of the single-mode laser in which with bias and periodical signals serve as inputs, combining with the effect of coloured pump noise, we use the linear approximation method to calculate the power spectrum and signal-to-noise ratio (SNR) of the laser intensity under the condition of pump noise and quantum noise cross-related in the form of δ function. It is found that with the change of pump noise correlation time, both SNR and the output power will occur stochastic resonance (SR). If the bias signal α is very small, changing the intensities of pump noise and quantum noise respectively does not lead to the appearance of SR in the SNR; while α increases to a certain number, SR appears.

  8. Cosmogenic and nucleogenic 3He in apatite, titanite, and zircon (United States)

    Farley, K. A.; Libarkin, J.; Mukhopadhyay, S.; Amidon, W.


    Cosmogenic 3He was measured in apatite, titanite, and zircon and cosmogenic 21Ne in quartz at 13 depth intervals in a 2.7-m long drill core in a Miocene ignimbrite from the Altiplano of Bolivia. All three 3He depth profiles as well as the 21Ne profile attenuate exponentially with depth, indicating that both of these isotopes are cosmogenic in origin with no significant contribution from other sources. The attenuation lengthscale for 3He production of Λ = 180 ± 11 g/cm 2 is consistent with expectations for neutron spallation, and is identical to that found for the cosmogenic 21Ne in quartz. By normalizing the measured 3He concentrations to 21Ne and using the independently known cosmogenic 21Ne production rate, the apparent cosmogenic 3He production rates in apatite, titanite, and zircon were respectively found to be 112, 97, and 87 atoms/g/yr at sea-level and high latitude. The formal uncertainty on these estimates is ˜ 20% (2 σ), and arises in equal parts from uncertainties in the measured 3He/ 21Ne ratios and the uncertainty in the 21Ne production rate. However an additional factor affecting the apparent 3He production rate in these phases arises from the long stopping range of spalled 3He and tritium (which decays to 3He). Because all three accessory phases have higher mean atomic number than major rock-forming minerals, they will have lower 3He production rates than their surroundings. As a consequence the long stopping ranges will cause a net implantation of 3He and therefore higher apparent production rates than would apply for purely in-situ production. Thus these apparent production rates apply only to the specific grain sizes analyzed. Analysis of sieved zircon aliquots suggests that a factor of 2 increase in grain size (from ˜ 50 to ˜ 100 μm cross-section) yields a 10% decrease in apparent production rate. While this effect warrants further study, the grain sizes analyzed here are typical of the accessory phases commonly encountered, so the apparent

  9. Solid-state led-pumped YAG:Nd/sup 3 +/ ring laser

    Energy Technology Data Exchange (ETDEWEB)

    Belozerov, S.A.; Korniyenko, L.S.; Kravtsov, N.V.; Kuratev, I.I.; Rusakov, S.I.; Stel' makh, M.F.; Shelayev, A.A.; Shelayev, A.N.


    The article is a report on attainment of stimulated emission in a YAG:Nd/sup 3 +/ solid-state ring laser (lambda = 1.06 with both cw and pulsed pumping by light-emitting diodes. The YAG:Nd/sup 3 +/ crystal was 1.5 mm in diameter and 20 mm long with Brewster faces. The laser was made as a monoblock in which channels were drilled for the laser beam. Total losses on the mirrors did not exceed 0.2%. Cavity perimeter was 22 cm. Pumping was by two lines of LEDs based on epitaxial heterostructure Al/sub x/Ga/sub 1-x/As. In the pulsed pumping mode maximum pulse duration was 8 ms, and maximum recurrence rate was 100 Hz. The threshold pumping current in the pulsed mode was about 1.1 A with prf of 10 Hz, pulse duration of 0.5 ms and temperature of 300 K. Maximum admissible current in this mode is 6 A. In cw pumping, the LED lines were fed by a stabilized DC source at voltage of about 40 V. Threshold pumping current was about 1.5 A, i.e., the threshold power was about 60 W. The optimum maximum current in the cw mode was about 2.0 A. Emission power was a near-linear function of current through the LEDs in either pumping mode. It was experimentally demonstrated that a rotating ring laser can produce stable beats with both cw and pulsed LED pumping. It should be possible to use self-switching modes to measure non-reciprocal effects. 5 references, 2 figures.

  10. Clad-pumped Er-nanoparticle-doped fiber laser (Conference Presentation) (United States)

    Baker, Colin C.; Friebele, E. Joseph; Rhonehouse, Daniel L.; Marcheschi, Barbara A.; Peele, John R.; Kim, Woohong; Sanghera, Jasbinder S.; Zhang, Jun; Chen, Youming; Pattnaik, Radha K.; Dubinskii, Mark


    Erbium-doped fiber lasers are attractive for directed energy weapons applications because they operate in a wavelength region that is both eye-safer and a window of high atmospheric transmission. For these applications a clad-pumped design is desirable, but the Er absorption must be high because of the areal dilution of the doped core vs. the pump cladding. High Er concentrations typically lead to Er ion clustering, resulting in quenching and upconversion. Nanoparticle (NP) doping of the core overcomes these problems by physically surrounding the Er ions with a cage of Al and O in the NP, which keeps them separated to minimize excited state energy transfer. A significant issue is obtaining high Er concentrations without the NP agglomeration that degrades the optical properties of the fiber core. We have developed the process for synthesizing stable Er-NP suspension which have been used to fabricate EDFs with Er concentrations >90 dB/m at 1532 nm. Matched clad fibers have been evaluated in a core-pumped MOPA with pump and signal wavelengths of 1475 and 1560 nm, respectively, and efficiencies of 72% with respect to absorbed pump have been obtained. We have fabricated both NP- and solution-doped double clad fibers, which have been measured in a clad-pumped laser testbed using a 1532 nm pump. The 1595 nm laser efficiency of the NP-doped fiber was 47.7%, which is high enough for what is believed to be the first laser experiment with the cladding pumped, NP-doped fiber. Further improvements are likely with a shaped cladding and new low-index polymer coatings with lower absorption in the 1500 - 1600 nm range.

  11. Diode-pumped 1.7-W erbium 3-µm fiber laser

    NARCIS (Netherlands)

    Jackson, Stuart D.; King, Terence A.; Pollnau, Markus


    We report what is to our knowledge the first 3-mm fiber laser of the 1-W class. 1.7 W of output power and 17.3% slope eff iciency (with respect to the launched pump power) at a wavelength of 2.71 mm are demonstrated from a double-clad erbium-doped ZBLAN fiber diode pumped at 790 nm. Energy transfer

  12. Enhanced performance of thin-disk lasers by pumping into the zero-phonon line. (United States)

    Weichelt, Birgit; Voss, Andreas; Abdou Ahmed, Marwan; Graf, Thomas


    Pumping Yb:YAG or Yb:LuAG into the zero-phonon line at 969 nm instead of using the common pump wavelength of 940 nm reduces the heat generation by 32%. In addition to the 3% increase of the Stokes efficiency, this significantly reduces the diffraction losses caused by the thermally induced phase distortions leading to a remarkable increase of the overall efficiency especially of fundamental-mode thin-disk lasers. Using this pumping scheme in an Yb:LuAG thin-disk laser, we achieved 742 W of nearly diffraction limited (M2≈1.5) output power at an unprecedented high optical efficiency of 58.5%. For multimode operation (M2≈15) the maximum optical efficiency of an Yb:YAG thin-disk laser was increased to 72%.

  13. Polarized three-photon-pumped laser in a single MOF microcrystal. (United States)

    He, Huajun; Ma, En; Cui, Yuanjing; Yu, Jiancan; Yang, Yu; Song, Tao; Wu, Chuan-De; Chen, Xueyuan; Chen, Banglin; Qian, Guodong


    Higher order multiphoton-pumped polarized lasers have fundamental technological importance. Although they can be used to in vivo imaging, their application has yet to be realized. Here we show the first polarized three-photon-pumped (3PP) microcavity laser in a single host-guest composite metal-organic framework (MOF) crystal, via a controllable in situ self-assembly strategy. The highly oriented assembly of dye molecules within the MOF provides an opportunity to achieve 3PP lasing with a low lasing threshold and a very high-quality factor on excitation. Furthermore, the 3PP lasing generated from composite MOF is perfectly polarized. These findings may eventually open up a new route to the exploitation of multiphoton-pumped solid-state laser in single MOF microcrystal (or nanocrystal) for future optoelectronic and biomedical applications.

  14. Femtosecond laser pumped by high-brightness coherent polarization locked diodes. (United States)

    Purnawirman; Phua, P B


    We demonstrate, for the first time to our knowledge, the use of a coherent polarization locked diode as the high-brightness pump source for a femtosecond laser. Four diode emitters are coherently locked to produce more than 5 W linearly polarized, narrow linewidth, and single-lobed pump beam. This gives >10× brightness improvement over the conventional diode array. The diode beam is then used to pump a Yb:KYW laser to obtain 2 W output with 57% slope efficiency in cw laser operation. By using a saturable absorber mirror, we achieved cw mode-locking operation with a 177 fs pulse width at an average power of 0.55 W.

  15. Compact resonantly intra-cavity pumped tunable Ho:Sc2SiO5 laser (United States)

    Yang, Xiao-tao; Song, En-zhe; Xie, Wen-qiang


    A compact intra-cavity pumped low threshold continuous-wave Ho:Sc2SiO5 laser is reported. The characteristics of output wavelength tuning are investigated by use a intra-cavity briefringent (BF) filter. A wavelength tunable range of 140 nm from 2020 to 2160 nm is achieved. For the free-running mode, the laser slope efficiency is 24.8%, when the output central wavelength is 2110 nm. The laser threshold is about 820 mW of incident pump power. With the BF filter, a maximum output power of 870 mW is obtained at the incident pump power of 5 W, corresponding to a slope efficiency of 20.3%. The characteristics of output wavelength verse the crystal temperature are also investigated.

  16. A stable gain-switched Ho:CYA laser resonantly pumped at 1922 nm (United States)

    Zhang, J. N.; Chen, B. H.; Shen, D. Y.; Xu, X. D.


    We report on a gain-switched Ho:CaYAlO4 laser resonantly pumped by a home-constructed high power Tm:fiber laser at ~1922 nm. Stable nanosecond single-pulse operation could be maintained when the continuous-wave pump signal was modulated at repetition rates of 60-100 kHz with an acousto-optic modulator. A pulse duration of 311 ns has been obtained at a 60 kHz repetition rate under a pump power level of 11 W. The temporal stability and simplicity of operation make this laser suitable for a variety of applications, such as spectroscopy, gas sensing, and as the seed source of a master oscillation power amplifier system.

  17. Solar radiation pumped solid state of lasers for Solar Power Satellites

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Ruiyi [New Jersey (United States)


    The Laser Solar Power Satellites (L-SPS) is the most promising way to overcome global energy and environmental and economical problems. The purpose was to use the favorable combination of solar radiation, modern lasers and the extremely promising phenomenon Optical Phase Conjugation (OPC). Direct conversion of solar energy to energy of a high-power laser beam has the advantage of high efficiency and precise energy transportation. In this paper, direct solar radiation pumping of the laser is compared with the pumping using the intermediate stage of the conversion of the solar radiation in electrical energy. Possible solid-state lasers that can be used in L-SPS are also discussed (including optical system and cooling system). [Spanish] Los Satelites de Energia Solar Laser (L-SPS) son la forma mas prometedora para contrarrestar los problemas globales de energia, ambientales y problemas economicos. El proposito fue el de usar la combinacion favorable de radiacion solar, laseres modernos y el fenomeno extremadamente prometedor de conjugacion de fase optica (OPC). La conversion directa de energia solar a energia de un rayo laser de alta potencia tiene la ventaja de la alta eficiencia y precision de la transportacion de la energia. En este documento la radiacion solar directa impulsada por el laser se compara con la impulsion usando el estado intermedio de conversion de la radiacion solar en energia electrica. Tambien se analizan los posibles laseres de estado solido que pueden usarse en L-SPS (incluyendo el sistema optico y el sistema de enfriamiento).

  18. Spectroscopic issues in optical polarization of 3He gas for Magnetic Resonance Imaging of human lungs (United States)

    Dohnalik, T.; Głowacz, B.; Olejniczak, Z.; Pałasz, T.; Suchanek, M.; Wojna, A.


    The Magnetic Resonance Imaging (MRI) of human lungs for diagnostic purposes became possible by using nuclear spin hyperpolarized noble gases, such as 3He. One of the methods to polarize 3He is the Metastability Exchange Optical Pumping (MEOP), which up to now has been performed at low pressure of about 1 mbar and in low magnetic field below 0.1 T (standard conditions). The equilibrium nuclear polarization can reach up to 80%, but it is dramatically reduced during the subsequent gas compression to the atmospheric pressure that is necessary for the lungs examination. Further polarization losses occur during the transportation of the gas to the hospital scanner. It was shown recently that up to 50% polarization can be obtained at elevated pressure exceeding 20 mbar, by using magnetic field higher than 0.1 T (nonstandard conditions). Therefore, following the construction of the low-field MEOP polarizer located in the lab, a dedicated portable unit was developed, which uses the magnetic field of the 1.5 T MR medical scanner and works in the continuous-flow regime. The first in Poland MRI images of human lungs in vivo were obtained on the upgraded to 3He resonance frequency Siemens Sonata medical scanner. An evident improvement in the image quality was achieved when using the new technique. The paper shows how spectroscopic measurements of 3He carried out in various experimental conditions led both to useful practical results and to significant progress in understanding fundamental processes taking place during MEOP.

  19. Influences of pump transitions on thermal effects of multi-kilowatt thulium-doped fiber lasers

    CERN Document Server

    Yang, Jianlong; Tang, Yulong; Xu, Jianqiu


    Thermal effects are critical constrains for developing high-power thulium-doped fiber lasers (TDFLs). In this paper, we numerically investigate the lasing and thermal characteristics of the TDFLs under different pump transitions. Our results show, the widely-used pump transition $^3H_6\\rightarrow^3H_4$, taking advantages of high-power high-efficiency laser diodes at $\\sim$0.8 $\\mu$m, may not be a superior choice for directly outputting multi-kilowatt at 2 $\\mu$m because of severe thermal problems. Meanwhile, using other pump transitions resulting 2-$\\mu$m emissions, especially the in-band pump transition $^3H_6\\rightarrow^3F_4$, will decrease the generated heat to a large extent. By optimizing the power filling factor of the gain fiber, we find a 2-$\\mu$m TDFL cladding-pumped at 1.9 $\\mu$m will lead to the laser slope efficiency close to its quantum efficiency (95\\%). The induced ultra-low quantum defect would be of great importance for power scaling. We thus propose tandem-pumped TDFLs for reducing the heat ...

  20. High power CW diode-side-pumped Nd:YAG rod laser

    Institute of Scientific and Technical Information of China (English)

    Hailin Wang(王海林); Weiling Huang(黄维玲); Zhuoyou Zhou(周卓尤); Hongbing Cao(曹红兵)


    We report on the characterization of a diode-side-pumped Nd:YAG rod laser operating at high CW output power. A four-fold pump configuration is designed and the pump light is directly coupled into the Nd:YAG rod without the help of any cylindrical lenses. The distribution of pump light in the Nd:YAG rod has been calculated by using ray tracing program. The thermal lens effect of the Nd:YAG rod has been experimentally measured. A maximum output power of 800 W at 1064 nm in multimode operation is obtained for a pump power of 2400 W with 33% optical-optical efficiency. At the same time, the maximum beam parameter product of 25 mm.mrad is achieved.

  1. Pharyngeal pumping continues after laser killing of the pharyngeal nervous system of C. elegans

    Energy Technology Data Exchange (ETDEWEB)

    Avery, L.; Horvitz, H.R. (Massachusetts Institute of Technology, Cambridge (USA))


    Using a laser microbeam to kill specific subsets of the pharyngeal nervous system of C. elegans, we found that feeding was accomplished by two separately controlled muscle motions, isthmus peristalsis and pumping. The single neuron M4 was necessary and sufficient for isthmus peristalsis. The MC neurons were necessary for normal stimulation of pumping in response to food, but pumping continued and was functional in MC- worms. The remaining 12 neuron types were also unnecessary for functional pumping. No operation we did, including destruction of the entire pharyngeal nervous system, abolished pumping altogether. When we killed all pharyngeal neurons except M4, the worms were viable and fertile, although retarded and starved. Since feeding is one of the few known essential actions controlled by the nervous system, we suggest that most of the C. elegans nervous system is dispensable in hermaphrodites under laboratory conditions. This may explain the ease with which nervous system mutants are isolated and handled in C. elegans.

  2. Reliable Optical Pump Architecture for Highly Coherent Lasers Used in Space Metrology Applications (United States)

    Erlig, Herman; Qiu, Yueming; Poberezhskiy, Ilya Y.; Meras, Patrick L.; Chang, Daniel H.; Wu, Yen-Hung


    The design and initial demonstration of a laser pump module (LPM) incorporating single-mode, grating-stabilized 808-nm diode lasers and a low-loss, high-port-count optical combiner are completed. The purpose of the developed LPM is to reliably pump an Nd:YAG crystal in the laser head (LH), which serves as the optical metrology source for SIMLite mission. Using the narrow-linewidth, single-mode laser diodes enables placement of the pump power near Nd adsorption peak, which enhances pumping efficiency. Grating stabilization allows for stable pump spectra as diode operating temperature and bias current change. The low-loss, high-port-count optical combiner enables efficient combining of tens of pumps. Overall, the module supports 5+ years of continuous operation at 2 W of pump power with reliability approaching 100 percent. The LPM consists of a laser diode farm (LDF) and a pump beam combiner (PBC). An array of 807- to 808-nm fiber-pigtailed laser diodes makes up the LDF. A Bragg grating in each 5- m core single-mode (SM) fiber pigtail acts to stabilize the lasing spectra over a range of diode operating conditions. These commercially available single-mode laser diodes can deliver up to 150 mW of optical power. The outputs from the multiple pumps in the LDF are routed to the PBC, which is a 37-input by 1-output all-fiber device. The input ports consist of 5- m core SM fiber, while the output port consists of 105- m core, 0.15 NA (numerical aperture) multi-mode (MM) fiber. The combiner is fabricated by fusing the 37 input fibers while simultaneously tapering the fused region. At the completion of this process, the MM fiber is spliced to the end of the adiabatic taper, and, for protection, the combiner is sheathed by a capillary tube. A compact and robust metal housing was designed and fabricated to protect the PBC during space deployment.

  3. Feasibility of an iodine gas laser pumped by concentrated terrestrial solar radiation

    Energy Technology Data Exchange (ETDEWEB)

    Terry, C.K.; Peterson, J.E.; Goswami, D.Y. [Univ. of Florida, Gainesville, FL (United States). Dept. of Mechanical Engineering


    A t-C{sub 4}F{sub 9}I iodine gas laser pumped by terrestrial sunlight was analyzed. Lasant properties, spectral terrestrial insolation data, and established laser fundamentals were used to develop a mathematical model of a terrestrial solar-pumped system. Threshold pumping power and available terrestrial pumping power were predicted and used to estimate the solar concentration required to initiate lasing. Laser output power was also predicted. Because this lasant is relatively new and has never been pumped by solar radiation, many physical properties are not well known. An uncertainty analysis was used to predict errors in threshold solar concentration and output power. In all cases, conservative estimates of physical properties were used. The dominant uncertainty in both threshold and output predictions was due to wide variation in published values of the quenching reaction caused by the lasant parent molecule. Several optical and geometric configurations were devised using commercially available primary solar collectors: parabolic or compound parabolic troughs, a Shenandoah-type 7.5 meter diameter parabolic dishes, or a 17 meter diameter stretched membrane dish. Threshold solar concentration for these systems ranged from below 50 to almost 200 suns depending on the laser tube geometry. Output power ranged from below 1 Watt to almost 90 Watts, and was a function of primary collector dimension.

  4. Ultrasound Attenuation in Liquid ^3He/High Porosity Aerogel (United States)

    Choi, H. C.; Mulders, N.


    High porosity silica aerogels have been extensively used to study the influence of disorder in p-wave superfluid ^3He. Experimental investigations performed during the last decade revealed three distinct superfluid phases in liquid ^3He /98% aerogel system. The three phases found in this system are called as A, B, and A1-like phases (using the same nomenclature as in the bulk), although only the spin component of the order parameter has been studied and found to resemble that of corresponding bulk phases. A complete understanding of the microscopic structure of the p-wave superfluid phases requires identification of both orbital and spin components of the order parameter. Until now, there is no experimental attempt to directly probe the orbital structure in ^3He/aerogel system. To resolve this issue, we performed acoustic measurements by direct transmission of ultrasound through the ^3He/98% aerogel sample. We will present and discuss our preliminary results.

  5. Supercontinuum Generation with Output Power of 1.7 W Pumped by a Picosecond Laser Pulse (United States)

    Pan, Er-Ming; Ruan, Shuang-Chen; Guo, Chun-Yu; Wang, Yun-Cai; Wei, Hui-Feng


    By using a photonic crystal fiber, a supercontinuum source with output power up to 1.7W, pumped by a passively mode-locked diode-pumped Nd:YVO4 picosecond laser is obtained. A spectral width of the supercontinuum is 1700 nm (500-2200 nm) with the 5 dB spectral width approximately 1000 nm (1200-2200 nm). This high power wide band supercontinuum source meets the demand of many applications such as optical coherence tomography, frequency metrology and wavelength-division-multiplexing systems. The evolution of the supercontinuum with the increasing pump power is presented and analyzed.

  6. Polarised two-photon excitation of quantum well excitons for manipulation of optically pumped terahertz lasers

    Energy Technology Data Exchange (ETDEWEB)

    Slavcheva, G., E-mail: [Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ (United Kingdom); Kavokin, A.V., E-mail: [School of Physics and Astronomy, University of Southampton, Highfield, Southampton SO17 1BJ (United Kingdom); Spin Optics Laboratory, St. Petersburg State University, 1, Ulyanovskaya 198504 (Russian Federation)


    Optical pumping of excited exciton states in a semiconductor quantum well embedded in a microcavity is a tool for realisation of ultra-compact terahertz (THz) lasers based on stimulated optical transition between excited (2p) and ground (1s) exciton state. We show that the probability of two-photon absorption by a 2p-exciton is strongly dependent on the polarisation of both pumping photons. Five-fold variation of the threshold power for terahertz lasing by switching from circular to co-linear pumping is predicted. We identify photon polarisation configurations for achieving maximum THz photon generation quantum efficiency.

  7. Laser printed graphene on polyimide electrodes for magnetohydrodynamic pumping of saline fluids

    KAUST Repository

    Khan, Mohammed Asadullah


    An efficient, scalable pumping device is reported that avoids moving parts and is fabricated with a cost-effective method. The magnetohydrodynamic pump has electrodes facilely made by laser printing of polyimide. The electrodes exhibit a low sheet resistance of 22.75 Ω/square. The pump is implemented in a channel of 240 mm2 cross-section and has an electrode length of 5 mm. When powered by 7.3 V and 12.43 mA/cm2, it produces 13.02 mm/s flow velocity.

  8. Flashlamp-pumped Ti:Sapphire laser with different rods grown by Czochralski and Verneuil methods (United States)

    Boquillon, J. P.; Said, J.


    The design and the development of a flashlamp-pumped Ti:Sapphire laser is described. Design criteria are discussed and performance improvements using different types of fluorescent UV converters or filters, such as organic dyes or doped glass are presented. We have tested different laser rods at various Ti-concentrations obtained by Verneuil or Czochralski growth techniques. The maximum laser output energy of 540 mJ with a differential efficiency up to 1% was achieved by using only a pyrex filter surrounding the laser rod.

  9. Green electron-beam pumped laser arrays based on II-VI nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Zverev, M.M.; Gamov, N.A.; Zdanova, E.V.; Studionov, V.B.; Peregoudov, D.V. [Moscow State Inst. of Radio Engineering, Electronics and Automations, Moscow (Russian Federation); Ivanov, S.V.; Sedova, I.V.; Gronin, S.V.; Sorokin, S.V.; Kop' ev, P.S. [Ioffe Physical Technical Inst., RAS Polytekhnicheskaya, St. Petersburg (Russian Federation); Olikhov, I.M. [Gamma Co. Ltd., SRC Platan, Fryazino (Russian Federation)


    Room temperature electron-beam pumped (U = 15-26 keV) green lasers and laser arrays based on multiple quantum well II-VI structures with an extended up to 2 {mu}m waveguide have been studied. The maximum achieved output pulse power is as high as 31 and 630 W per facet from a single 0.24-mm-wide laser element at the cavity length of 0.4 mm and a laser array consisting of 26 elements, respectively. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

  10. The 3He spectral function in light-front dynamics

    Directory of Open Access Journals (Sweden)

    Rinaldi Matteo


    Full Text Available A distorted spin-dependent spectral function for 3He is considered for the extraction of the transverse-momentum dependent parton distributions in the neutron from semi-inclusive deep inelastic electron scattering off polarized 3He at finite momentum transfers, where final state interactions are taken into account. The generalization of the analysis to a Poincaré covariant framework within the light-front dynamics is outlined.

  11. The 3He spectral function in light-front dynamics

    CERN Document Server

    Rinaldi, Matteo; Kaptari, Leonid; Pace, Emanuele; Salmè, Giovanni; Scopetta, Sergio


    A distorted spin-dependent spectral function for 3He is considered for the extraction of the transverse-momentum dependent parton distributions in the neutron from semi-inclusive deep inelastic electron scattering off polarized 3He at finite momentum transfers, where final state interactions are taken into account. The generalization of the analysis to a Poincar\\'e covariant framework within the light-front dynamics is outlined.

  12. Polar Phase of Superfluid (3)He in Anisotropic Aerogel. (United States)

    Dmitriev, V V; Senin, A A; Soldatov, A A; Yudin, A N


    We report the first observation of the polar phase of superfluid (3)He. This phase appears in (3)He confined in a new type of aerogel with a nearly parallel arrangement of strands which play the role of ordered impurities. Our experiments qualitatively agree with theoretical predictions and suggest that in other systems with unconventional Cooper pairing (e.g., in unconventional superconductors) similar phenomena may be found in the presence of anisotropic impurities.

  13. Strong-coupling and the Stripe phase of $^3$He


    Wiman, Joshua J.; Sauls, J. A.


    Thin films of superfluid $^3$He were predicted, based on weak-coupling BCS theory, to have a stable phase which spontaneously breaks translational symmetry in the plane of the film. This crystalline superfluid, or "stripe" phase, develops as a one dimensional periodic array of domain walls separating degenerate B phase domains. We report calculations of the phases and phase diagram for superfluid $^3$He in thin films using a strong-coupling Ginzburg-Landau theory that accurately reproduces th...

  14. End pumped yellow laser performance of Dy3+:ZnWO4 (United States)

    Xia, Zhongchao; Yang, Fugui; Qiao, Liang; Yan, Fengpo


    We report an end pumped single transverse-mode (TEM00) yellow laser based on Dy3+:ZnWO4 crystal. The pump light is InGaN blue laser diode at 450 nm with the maximum power of 1.5 W. A 3 cm length Dy3+:ZnWO4 crystal served as the gain medium. By way of the square filter, we discuss the TEM00 properties. In continuous-wave operation and single transverse-mode, a maximum output power of 0.110 W and a slope efficiency of 13.0% are achieved at an emission wavelength of 575 nm.

  15. Determination of Thermal Conductivity of Liquids by a Multi-Point Laser Pump Method

    Institute of Scientific and Technical Information of China (English)

    MA Di; KUO Pao-Kuang; XU Xiao-Dong; ZHANG Shu-Yi


    As an advanced optical method, a multi-point pump method is presented for measurements of thermo-physical properties of liquids. Meanwhile, based on the laser-induced thermal grating method, a new theory model is presented and used to analyse the thermal effects caused by the multi-point laser pump, by which the thermal conductivity of liquids can be obtained. The results of some typical liquids, such as water, ethanol and acetone, are presented and are consistent with those of acknowledged values, demonstrating that the multi-point method is simple and useful for characterizing thermal properties of liquids.

  16. Research on fission induced plasmas and nuclear pumped lasers at the Los Alamos Scientific Laboratory (United States)

    Helmick, H. H.


    A program of research on gaseous uranium and uranium plasmas is being conducted at The Los Alamos Scientific Laboratory under sponsorship of the National Aeronautics and Space Administration. The objective of this work is twofold: (1) to demonstrate the proof of principle of a gaseous uranium fueled reactor, and (2) pursue fundamental research on nuclear pumped lasers. The relevancy of the two parallel programs is embodied in the possibility of a high-performance uranium plasma reactor being used as the power supply for a nuclear pumped laser system. The accomplishments in the two above fields are summarized

  17. K^- ^3He and K^+K^- interactions in the reaction pd -> ^3He K^+K^-

    CERN Document Server

    Grishina, V Yu; Kondratyuk, L A


    We investigate the K^- ^3He and K^+K^- interactions in the reaction pd -> ^3He K^+K^- near threshold and compare our model calculations with data from the MOMO experiment at COSY-Juelich. The data do not support a strong attraction between the K^- and ^3He system needed for formation of deeply bound K^- nuclear states. We also estimate upper limits for the a_0(980) and f_0(980) contributions to the produced K^+ K^- pairs.

  18. Spatial Combining of Laser-Diode Beams for Pumping an NPRO (United States)

    Gelsinger, Paul; Liu, Duncan; Mulder, Jerry; Aguayo, Francisco


    A free-space optical beam combiner now undergoing development makes it possible to use the outputs of multiple multimode laser diodes to pump a neodymium-doped yttrium aluminum garnet (Nd:YAG) non-planar ring oscillator (NPRO) laser while ensuring that the laser operates at only a single desired frequency. Heretofore, a Nd:YAG NPRO like the present one has been pumped by a single multimode laser-diode beam delivered via an optical fiber. It would be desirable to use multiple pump laser diodes to increase reliability beyond that obtainable from a single pump laser diode. However, as explained in this article, simplistically coupling multiple multimode laser-diode beams through a fiber-optic combiner would entail a significant reduction in coupling efficiency, and lasing would occur at one or more other frequencies in addition to the single desired frequency. To minimize coupling loss, one must ensure that the NA (approximately equal to 0.3) of the combined laser-diode beams is less than the NA of the fiber. The A(Omega) of the laser-diode beam in the slow-axis plane is 1/1.3 as large as that of the fiber. This A(Omega) is small enough to enable efficient coupling of light into the optical fiber, but too large for combining of beams in the slow-axis plane. Therefore, a pair of cylindrical lenses is used to cancel the slow-axis plane magnification introduced by the on-cylindrical lenses used to effect magnification in the fast-axis plane.


    Institute of Scientific and Technical Information of China (English)



    We report on the implementation of a KTP optical parametric oscillator pumped by a pulsed tunable Ti:sapphire laser. Two major improvements were achieved, including the connection of the signal and idler tuning ranges and the high-output conversion efficiency through the signal and idler tuning ranges. Both in the signal and idler, the continuous output wavelength from 1.261 to 2.532μm was obtained by varying the pump wavelength from 0.7 to 0.98μm. The maximum output pulse energy was 27.2mJ and the maximum conversion efficiency was 35.7% at 1.311μm (signal).

  20. A 3 He-129 Xe co-magnetometer with 87 Rb magnetometry (United States)

    Limes, Mark; Sheng, Dong; Romalis, Mike


    We report progress on a 3 He-129 Xe co-magnetometer detected with a 87 Rb magnetometer. The noble-gas co-magnetometer is insensitive to any long-term bias field drifts, but the presence of hot Rb can cause instability in the ratio of 3 He-129 Xe precession frequencies. We use a sequence of Rb π pulses to suppress the instability due to Rb-noble gas interactions by a factor of 104 along all three spatial axes. For detection, our 87 Rb magnetometer operates using single-axis 87 Rb π pulses with σ+ /σ- pumping-this technique decouples the 87 Rb magnetometer from bias fields, and allows for SERF operation. We are presently investigating systematic effects due to combinations of several imperfections, such as longitudinal noble gas polarization, imperfect 87 Rb π pulses, and 87 Rb pump light shifts. Thus far, our 87 Rb magnetometer has a sensitivity of 40 fT/√{Hz}, and our 3 He-129 Xe co-magnetometer has achieved a single-shot precession frequency ratio error of 20 nHz and a long-term bias drift of 8 nHz at 7 h. We are developing the co-magnetometer for use as an NMR gyro, and to search for possible spin-gravity interactions. Supported by DARPA and NSF.

  1. 3-He in the Milky Way Interstellar Medium: Ionization Structure

    CERN Document Server

    Bania, T M; Rood, Robert T; Wilson, T L; LaRocque, Jennifer M


    The cosmic abundance of the 3-He isotope has important implications for many fields of astrophysics. We are using the 8.665 GHz hyperfine transition of 3-He+ to determine the 3-He/H abundance in Milky Way HII regions and planetary nebulae. This is one in a series of papers in which we discuss issues involved in deriving accurate 3-He/H abundance ratios from the available measurements. Here we describe the ionization correction we use to convert the 3-He+/H+ abundance, y3+, to the 3-He/H abundance, y3. In principle the nebular ionization structure can significantly influence the y3 derived for individual sources. We find that in general there is insufficient information available to make a detailed ionization correction. Here we make a simple correction and assess its validity. The correction is based on radio recombination line measurements of H+ and 4-He+, together with simple core-halo source models. We use these models to establish criteria that allow us to identify sources that can be accurately corrected...

  2. Bragg-Scattering Four-Wave Mixing in Nonlinear Fibers with Intracavity Frequency-Shifted Laser Pumps

    Directory of Open Access Journals (Sweden)

    Katarzyna Krupa


    Full Text Available We experimentally study four-wave mixing in highly nonlinear fibers using two independent and partially coherent laser pumps and a third coherent signal. We focus our attention on the Bragg-scattering frequency conversion. The two pumps were obtained by amplifying two Intracavity frequency-shifted feedback lasers working in a continuous wave regime.

  3. Diode end-pumped 1123-nm Nd:YAG laser with 2.6-W output power

    Institute of Scientific and Technical Information of China (English)

    Zhiqiang Cai; Meng Chen; Zhigang Zhang; Rui Zhou; Wuqi Wen; Xin Ding; Jianquan Yao


    We present a compact and high output power diode end-pumped Nd:YAG laser which operates at the wavelength of 1123 nm. Continuous wave (CW) laser output of 2.6 W was achieved at the incident pump power of 15.9 W, indicating an overall optical-optical conversion efficiency of 16.4%, and the slope efficiency was 18%.

  4. Highly efficient cascaded P-doped Raman fiber laser pumped by Nd:YVO4 solid-state laser

    Institute of Scientific and Technical Information of China (English)

    Chaohong Huang; Zhiping Cai; Zhengqian Luo; Wencai Huang; Huiying Xu; Chenchun Ye


    A highly efficient cascaded P-doped Raman fiber laser (RFL) pumped by a 1064-nm continuous wave (CW) Nd:YVO4 solid-state laser is reported. 1.15-W CW output power at 1484 nm is obtained while the input pump power is 4 W, corresponding to the power conversion efficiency of 28.8%. The threshold pump power for the second-order Stokes radiation is 1.13 W. The slope efficiency is as high as 42.6%. The experimental results are in good agreement with theoretical ones. Furthermore, the power instability of the P-doped RFL at 1484 nm in an hour is observed to be less than 5%.

  5. Comparison of fiber lasers based on distributed side-coupled cladding-pumped fibers and double-cladding fibers. (United States)

    Huang, Zhihe; Cao, Jianqiu; Guo, Shaofeng; Chen, Jinbao; Xu, Xiaojun


    We compare both analytically and numerically the distributed side-coupled cladding-pumped (DSCCP) fiber lasers and double cladding fiber (DCF) lasers. We show that, through optimization of the coupling and absorbing coefficients, the optical-to-optical efficiency of DSCCP fiber lasers can be made as high as that of DCF lasers. At the same time, DSCCP fiber lasers are better than the DCF lasers in terms of thermal management.

  6. Polarized 3He Gas Circulating Technologies for Neutron Analyzers

    Energy Technology Data Exchange (ETDEWEB)

    Watt, David; Hersman, Bill


    We describe the development of an integrated system for quasi-continuous operation of a large volume neutron analyzer. The system consists of a non-magnetic diaphragm compressor, a prototype large volume helium polarizer, a surrogate neutron analyzer, a non-depolarizing gas storage reservoir, a non-ferrous valve manifold for handling gas distribution, a custom rubidium-vapor gas return purifier, and wire-wound transfer lines, all of which are immersed in a two-meter external magnetic field. Over the Phase II period we focused on three major tasks required for the successful deployment of these types of systems: 1) design and implementation of gas handling hardware, 2) automation for long-term operation, and 3) improvements in polarizer performance, specifically fabrication of aluminosilicate optical pumping cells. In this report we describe the design, implementation, and testing of the gas handling hardware. We describe improved polarizer performance resulting from improved cell materials and fabrication methods. These improvements yielded valved 8.5 liter cells with relaxation times greater than 12 hours. Pumping this cell with 1500W laser power with 1.25nm linewidth yielded peak polarizations of 60%, measured both inside and outside the polarizer. Fully narrowing this laser to 0.25nm, demonstrated separately on one stack of the four, would have allowed 70% polarization with this cell. We demonstrated the removal of 5 liters of polarized helium from the polarizer with no measured loss of polarization. We circulated the gas through a titanium-clad compressor with polarization loss below 3% per pass. We also prepared for the next phase of development by refining the design of the polarizer so that it can be engineer-certified for pressurized operation. The performance of our system far exceeds comparable efforts elsewhere.

  7. Towards jitter-free pump-probe measurements at seeded free electron laser facilities. (United States)

    Danailov, Miltcho B; Bencivenga, Filippo; Capotondi, Flavio; Casolari, Francesco; Cinquegrana, Paolo; Demidovich, Alexander; Giangrisostomi, Erika; Kiskinova, Maya P; Kurdi, Gabor; Manfredda, Michele; Masciovecchio, Claudio; Mincigrucci, Riccardo; Nikolov, Ivaylo P; Pedersoli, Emanuele; Principi, Emiliano; Sigalotti, Paolo


    X-ray free electron lasers (FEL) coupled with optical lasers have opened unprecedented opportunities for studying ultrafast dynamics in matter. The major challenge in pump-probe experiments using FEL and optical lasers is synchronizing the arrival time of the two pulses. Here we report a technique that benefits from the seeded-FEL scheme and uses the optical seed laser for nearly jitter-free pump-probe experiments. Timing jitter as small as 6 fs has been achieved and confirmed by measurements of FEL-induced transient reflectivity changes of Si3N4 using both collinear and non-collinear geometries. Planned improvements of the experimental set-up are expected to further reduce the timing jitter between the two pulses down to fs level.

  8. A solar simulator-pumped gas laser for the direct conversion of solar energy (United States)

    Weaver, W. R.; Lee, J. H.


    Most proposed space power systems are comprised of three general stages, including the collection of the solar radiation, the conversion to a useful form, and the transmission to a receiver. The solar-pumped laser, however, effectively eliminates the middle stage and offers direct photon-to-photon conversion. The laser is especially suited for space-to-space power transmission and communication because of minimal beam spread, low power loss over large distances, and extreme energy densities. A description is presented of the first gas laser pumped by a solar simulator that is scalable to high power levels. The lasant is an iodide C3F7I that as a laser-fusion driver has produced terawatt peak power levels.

  9. Dual-wavelength stable nanosecond pulses generation from cladding-pumped fiber laser

    Institute of Scientific and Technical Information of China (English)

    Shuling Hu; Jing Yu; Chunqing Gao; Guanghui Wei; Fuyun Lü


    In this paper, the generation of dual-wavelength stable nanosecond pulses by a laser diode pumped Ybdoped double-clad fiber laser is presented. In the experiment, the fiber laser with two-mirror cavity is approved which operates in a self-Q-switching regime. The Q-switching mechanism is based on stimulatedBrillouin scattering (SBS). When the pump power achieves the SBS threshold, the fiber laser changes from the start resonator to the SBS resonator. With different reflectivities of the second mirror, stable dual-wavelength pulses with the pulse width range from 10 ns to less than 2 ns are obtained. The resultwas explained theoretically by birefringency (including stochastic birefringency and bend birefringency).

  10. 80-W cw TEM{sub 00} IR beam generation by use of a laser-diode-side-pumped Nd:YAG rod laser

    Energy Technology Data Exchange (ETDEWEB)

    Konno, Susumu; Fujikawa, Shuichi; Yasui, Koji [Mitsubishi Electric Corp. Amagasaki, Hyogo (Japan). Advanced Technology R and D Center


    We have demonstrated high-efficient and high-power operation of a diode-side-pumped Nd:YAG rod laser. The laser has a simple and scalable configuration consisting of a diffusive pumping reflector and an advanced cavity configuration for polarization-dependent bifocusing compensation. (author)

  11. Dynamics of an erbium-doped fiber laser subjected to harmonic modulation of a diode pump laser (United States)

    Pisarchik, Alexander N.; Kir'yanov, Alexander V.; Barmenkov, Yuri O.; Reategui, R. J.


    An erbium-doped fiber laser is shown to operate as a bistable or multistable nonlinear system under harmonic modulation of the diode pump laser. Phase- and frequency-dependent states are demonstrated both experimentally and in numerical simulations through codimensional-one and codimensional-two bifurcation diagrams in the parameter space of the modulation frequency and amplitude. In particular, generalized bistability results in doubling of saddle-node bifurcation lines where different coexisting attractors born. The laser model describes well all experimental features.

  12. High-speed off-axis holographic cinematography with a copper-vapor-pumped dye laser. (United States)

    Lauterborn, W; Judt, A; Schmitz, E


    A series of coherent light pulses is generated by pumping a dye laser with the pulsed output of a copper-vapor laser at rates of as much as 20 kHz. Holograms are recorded at this pulse rate on a rotating holographic plate. This technique of high-speed holographic cinematography is demonstrated by viewing the bubble filaments that appear in water under the action of a sound field of high intensity.

  13. An Al sub 2 O sub 3 :Ti(3+) laser with microsecond flashlamp pumping

    Energy Technology Data Exchange (ETDEWEB)

    Gorelenko, A.IA.; Demidovich, A.A.; Kalosha, I.I.; Nabatov, V.V.; Sevast' ianov, B.K. (Institut Kristallografii, Moscow (USSR) Institut Fiziki, Minsk (Belorussian SSR))


    The paper presents results of the optimization of a flashlamp-pumped Al2O3:Ti(3+) laser using fluorescent light converters. Two types of converters were tested, i.e., a liquid one and a polymeric one using coumarin-30 dye. The maximum laser output energy amounted to 130 mJ with a differential efficiency of 0.4 percent. The wavelength tuning range was from 685 to 920 nm. 6 refs.

  14. Multimode distributed feedback laser emission in a dye-doped optically pumped polymer thin-film (United States)

    Sobel, F.; Gindre, D.; Nunzi, J.-M.; Denis, C.; Dumarcher, V.; Fiorini-Debuisschert, C.; Kretsch, K. P.; Rocha, L.


    We report on particular features of thin film distributed feedback (DFB) lasers. Devices are optically pumped using a Lloyd-mirror interferometer. For a given DFB grating period, the number of lasing modes is film thickness dependent. Spectral content of the devices is analysed using planar waveguide theory. An excellent agreement between the theoretical transverse electric mode structure and the laser emission spectrum is found.

  15. Frequency-stabilized diode-pumped Nd:YAG laser of high power

    Energy Technology Data Exchange (ETDEWEB)

    Taccheo, S.; Laporta, P.; Longhi, S. [CNR, Milano (Italy). Centro di Elettronica Quantistica e Strumentazione Elettronica]|[Politecnico di Milano (Italy). Dipt. di Fisica; Svelto, C. [Politecnico di Milano (Italy). Dipt. di Elettronica e Informazione


    The authors describe a frequency-stabilized diode-pumped Nd:YAG laser of high power whose single-mode operation is obtained by suppressing the spatial hole burning through the twisted-mode technique. Active frequency stabilization is achieved by fringe side locking the laser beam to a reference Fabry-Perot cavity. Output power up to 800 mW in single-transverse and -longitudinal mode operation with a linewidth of less than 20 kHz is obtained.

  16. Temperature variation induced by the pulsed-periodic laser pumping under terahertz wave generation (United States)

    Kitaeva, G. Kh; Moiseenko, E. V.; Shepelev, A. V.


    During nonlinear-optical parametric frequency conversion the heat-related effects occur, considerably influencing the conversion process. We develop versatile methods for analytic and numerical calculations of thermo-optical parameters and the temperature distribution inside a non-linear crystal pumped by periodic laser pulses. As an example, numerical results are presented for a number of laser-based schemes actual for the non-linear optical terahertz wave generation and parametric frequency conversion processes.

  17. A 980 nm pseudomorphic single quantum well laser for pumping erbium-doped optical fiber amplifiers (United States)

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


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

  18. Design of high-brightness TEM00-mode solar-pumped laser for renewable material processing (United States)

    Liang, D.; Almeida, J.


    The conversion of sunlight into laser light by direct solar pumping is of ever-increasing importance because broadband, temporally constant, sunlight is converted into laser light, which can be a source of narrowband, collimated, rapidly pulsed, radiation with the possibility of obtaining extremely high brightness and intensity. Nonlinear processes, such as harmonic generation, might be used to obtain broad wavelength coverage, including the ultraviolet wavelengths, where the solar flux is very weak. The direct excitation of large lasers by sunlight offers the prospect of a drastic reduction in the cost of coherent optical radiation for high average power materials processing. This renewable laser has a large potential for many applications such as high-temperature materials processing, renewable magnesium-hydrogen energy cycle and so on. We propose here a scalable TEM00 mode solar laser pumping scheme, which is composed of four firststage 1.13 m diameter Fresnel lenses with its respective folding mirrors mounted on a two-axis automatic solar tracker. Concentrated solar power at the four focal spots of these Fresnel lenses are focused individually along a common 3.5 mm diameter, 70 mm length Nd:YAG rod via four pairs of second-stage fused-silica spherical lenses and third-stage 2D-CPCs (Compound Parabolic Concentrator), sitting just above the laser rod which is also double-pass pumped by four V-shaped pumping cavities. Distilled water cools both the rod and the concentrators. 15.4 W TEM00 solar laser power is numerically calculated, corresponding to 6.7 times enhancement in laser beam brightness.

  19. First results from Tyrex, the new polarized-{sup 3}He filling station at ILL

    Energy Technology Data Exchange (ETDEWEB)

    Andersen, K.H. [Institut Laue-Langevin, 6, rue J. Horowitz, F-38042 Grenoble Cedex 9 (France)]. E-mail:; Chung, R. [Institut Laue-Langevin, 6, rue J. Horowitz, F-38042 Grenoble Cedex 9 (France); Guillard, V. [Institut Laue-Langevin, 6, rue J. Horowitz, F-38042 Grenoble Cedex 9 (France); Humblot, H. [Institut Laue-Langevin, 6, rue J. Horowitz, F-38042 Grenoble Cedex 9 (France); Jullien, D. [Institut Laue-Langevin, 6, rue J. Horowitz, F-38042 Grenoble Cedex 9 (France); Lelievre-Berna, E. [Institut Laue-Langevin, 6, rue J. Horowitz, F-38042 Grenoble Cedex 9 (France); Petoukhov, A. [Institut Laue-Langevin, 6, rue J. Horowitz, F-38042 Grenoble Cedex 9 (France); Tasset, F. [Institut Laue-Langevin, 6, rue J. Horowitz, F-38042 Grenoble Cedex 9 (France)


    A new filling station for nuclear polarisation of {sup 3}He gas has been constructed at the ILL, Grenoble. The 'Tyrex' machine uses metastability-exchange optical pumping for polarising the {sup 3}He gas at about 1 mbar pressure. The gas is then compressed up to several bars via a hydraulic titanium-alloy piston compressor. The machine can provide about 1.5 bar-l/h of polarised gas--an order-of-magnitude increase over the first filling station installed at the ILL in 1996. The compressed, polarised gas is used for polarising neutron beams for condensed-matter and fundamental physics experiments. First results are presented and examples of implementations on existing neutron instruments at ILL are described.

  20. Primary populations of metastable antiprotonic $^{4}He$ and $^{3}He$ atoms

    CERN Document Server

    Hori, Masaki; Hayano, R S; Ishikawa, T; Sakuguchi, J; Tasaki, T; Widmann, E; Yamaguchi, H; Torii, H A; Juhász, B; Horváth, D; Yamazaki, T


    Initial population distributions of metastable antiprotonic **4He and **3He atoms over principal and angular momentum quantum numbers were investigated using laser spectroscopy. The total fractions of antiprotons captured into the metastable states of the atoms were deduced. Cascade calculations were performed using the measure populations to reproduce the delayed annihilation time spectrum. Results showed agreement between the simulated and measured spectra. (Edited abstract) 30 Refs.

  1. Reducing temperature dependence of the output energy of a quasi-continuous wave diode-pumped Nd:YAG laser. (United States)

    Lee, Kangin; Kim, Youngjung; Lee, Sijin; Kwon, Jin Hyuk; Gwak, Jin Seog; Yi, Jonghoon


    It is demonstrated by numerical modeling that spectrally dispersed compound pumping diodes and low-loss pumping chamber reduced the temperature dependence of the output energy of quasi-continuous wave diode-pumped Nd:YAG lasers considerably. Several compound diodes with different spectral profiles were tested for pumping. The laser energy was calculated as a function of diode temperature from -30°C to 60°C. When a compound diode with a flat-top spectrum was used for pumping, the mean laser energy was 83% of the maximum energy of a Nd:YAG laser pumped by a diode with a narrow bandwidth. In addition, a compound diode with three emission lines was tested for pumping. When the wavelength gap between the adjacent emission lines of the pumping diode was in the range of 3-10 nm, the mean energy of the Nd:YAG laser became similar to that of a Nd:YAG laser pumped by a diode with a flat-top spectrum.

  2. Reversing the Pump-Dependence of a Laser at an Exceptional Point

    CERN Document Server

    Brandstetter, M; Deutsch, C; Klang, P; Schöberl, J; Türeci, H E; Strasser, G; Unterrainer, K; Rotter, S


    When two resonant modes in a system with gain or loss coalesce in both their resonance position and their width, a so-called "Exceptional Point" occurs which acts as a source of non-trivial physics in a diverse range of systems. Lasers provide a natural setting to study such "non-Hermitian degeneracies", since they feature resonant modes and a gain material as their basic constituents. Here we show that Exceptional Points can be conveniently induced in a photonic molecule laser by a suitable variation of the applied pump. Using a pair of coupled micro-disk quantum cascade lasers, we demonstrate that in the vicinity of these Exceptional Points the laser shows a characteristic reversal of its pump-dependence, including a strongly decreasing intensity of the emitted laser light for increasing pump power. This result establishes photonic molecule lasers as promising tools for exploring many further fascinating aspects of Exceptional Points, like a strong line-width enhancement and the coherent perfect absorption ...

  3. Selective removal of dental caries with a diode-pumped Er:YAG laser (United States)

    Yan, Ruth; Chan, Kenneth H.; Tom, Henry; Simon, Jacob C.; Darling, Cynthia L.; Fried, Daniel


    Selective removal of caries lesions with high precision is best accomplished using lasers operating at high pulse repetition rates utilizing small spot sizes. Conventional flash-lamp pumped Er:YAG lasers are poorly suited for this purpose, but new diode-pumped Er:YAG lasers have become available operating at high pulse repetition rates. The purpose of this study was to measure the ablation rate and selectivity of sound and demineralized enamel and dentin for a 30 W diode-pumped Er:YAG laser operating with a pulse duration of 20-30-μs and evaluate it's potential for the selective removal of natural occlusal lesions on extracted teeth. Microradiography was used to determine the mineral content of the demineralized enamel and dentin of 300-μm thick sections with natural caries lesions prior to laser ablation. The ablation rate was calculated for varying mineral content. In addition, near-IR reflectance measurements at 1500-1700- nm were used to guide the laser for the selective ablation of natural occlusal caries lesions on extracted teeth.

  4. Femtosecond laser direct writing of single mode polymer micro ring laser with high stability and low pumping threshold. (United States)

    Parsanasab, Gholam-Mohammad; Moshkani, Mojtaba; Gharavi, Alireza


    We have demonstrated an optically pumped polymer microring laser fabricated by two photon polymerization (TPP) of SU-8. The gain medium is an organic dye (Rhodamine B) doped in SU-8, and the laser cavity is a double coupled microring structure. Single mode lasing was obtained from the two coupled rings each with 30 µm and 29 µm radii using Vernier effect. Low laser threshold of 0.4 µJ/mm(2) is achieved using 1 µm wide polymer waveguides and the quality factor is greater than 10(4) at 612.4 nm wavelength. The lasing remained stable with pump energies from threshold to energies as high as 125 times the threshold.

  5. Transverse effects in a microchip laser with asymmetric end-pumping: modal interference and dynamic instability

    CERN Document Server

    Otsuka, K; Makino, H; Ohtomo, T; Okamoto, A


    Formation of complicated emission patterns consisting of many transverse modes and associated intensity pulsations at beat frequencies between some pairs of transverse eigenmodes in microchip solid-state lasers with laser-diode asymmetric end-pumping are reviewed. The dependence of billiard-like transverse patterns on pump power and crystal rotation (i.e. kaleidoscopic patterns) was demonstrated in a 0.3 mm thick thin-slice LiNdP sub 4 O sub 1 sub 2 laser with sheet-like end-pumping. Pump-power-dependent high-speed self-pulsations were observed. The asymmetric optical confinement resulted in the formation of transverse patterns which were totally different from normal Hermite-Gaussian resonator modes. The interference among pairs of non-orthogonal transverse eigenmode fields, whose energy levels exhibited avoided crossing with increasing pump power, was shown to result in high-speed intensity modulations. A good numerical reproduction of the observed high-speed modulations was obtained with model equations. (...

  6. High-brightness, fiber-coupled pump modules in fiber laser applications (United States)

    Hemenway, Marty; Urbanek, Wolfram; Hoener, Kylan; Kennedy, Keith W.; Bao, Ling; Dawson, David; Cragerud, Emily S.; Balsley, David; Burkholder, Gary; Reynolds, Mitch; Price, Kirk; Haden, Jim; Kanskar, Manoj; Kliner, Dahv A.


    High-power, high-brightness, fiber-coupled pump modules enable high-performance industrial fiber lasers with simple system architectures, multi-kW output powers, excellent beam quality, unsurpassed reliability, and low initial and operating costs. We report commercially available (element™), single-emitter-based, 9xx nm pump sources with powers up to 130 W in a 105 μm fiber and 250 W in a 200 μm fiber. This combination of high power and high brightness translates into improved fiber laser performance, e.g., simultaneously achieving high nonlinear thresholds and excellent beam quality at kW power levels. Wavelength-stabilized, 976 nm versions of these pumps are available for applications requiring minimization of the gain-fiber length (e.g., generation of high-peak-power pulses). Recent prototypes have achieved output powers up to 300 W in a 200 μm fiber. Extensive environmental and life testing at both the chip and module level under accelerated and real-world operating conditions have demonstrated extremely high reliability, with innovative designs having eliminated package-induced-failure mechanisms. Finally, we report integrated Pump Modules that provide conveniently formatted for fiber-laser pumping or direct-diode applications; these 19" rack-mountable, 2U units combine the outputs of up to 14 elements™ using fused-fiber combiners, and they include high-efficiency diode drivers and safety sensors.

  7. 1.34μm Nd:YVO4 high efficiency laser end-pumped by diode-laser of flat-concave cavity type

    Institute of Scientific and Technical Information of China (English)

    Shang Lian-Ju; Ning Ji-Ping


    The parameters of 1.34μm Nd:YVO4 laser end-pumped with flat-concave cavity are theoretically analysed. The analysis in this paper may be helpful to the designing of kindred lasers. The operation of 1.34μm Nd:YVO4 laser end-pumped by a diode-laser with flat-concave cavity is achieved. The output power of 3.51W at 1.34μm and optical to optical conversion efficiency of 39.0% are obtained at the pump power of 9.0W.

  8. PUMPS (United States)

    Thornton, J.D.


    A pump is described for conveving liquids, particure it is not advisable he apparatus. The to be submerged in the liquid to be pumped, a conduit extending from the high-velocity nozzle of the injector,and means for applying a pulsating prcesure to the surface of the liquid in the conduit, whereby the surface oscillates between positions in the conduit. During the positive half- cycle of an applied pulse liquid is forced through the high velocity nozzle or jet of the injector and operates in the manner of the well known water injector and pumps liquid from the main intake to the outlet of the injector. During the negative half-cycle of the pulse liquid flows in reverse through the jet but no reverse pumping action takes place.

  9. Carrier-Envelope Offset Stabilized Ultrafast Diode-Pumped Solid-State Lasers

    Directory of Open Access Journals (Sweden)

    Stéphane Schilt


    Full Text Available Optical frequency combs have been revolutionizing many research areas and are finding a growing number of real-world applications. While initially dominated by Ti:Sapphire and fiber lasers, optical frequency combs from modelocked diode-pumped solid-state lasers (DPSSLs have become an attractive alternative with state-of-the-art performance. In this article, we review the main achievements in ultrafast DPSSLs for frequency combs. We present the current status of carrier-envelope offset (CEO frequency-stabilized DPSSLs based on various approaches and operating in different wavelength regimes. Feedback to the pump current provides a reliable scheme for frequency comb CEO stabilization, but also other methods with faster feedback not limited by the lifetime of the gain material have been applied. Pumping DPSSLs with high power multi-transverse-mode diodes enabled a new class of high power oscillators and gigahertz repetition rate lasers, which were initially not believed to be suitable for CEO stabilization due to the pump noise. However, this challenge has been overcome, and recently both high power and gigahertz DPSSL combs have been demonstrated. Thin disk lasers have demonstrated the highest pulse energy and average power emitted from any ultrafast oscillator and present a high potential for the future generation of stabilized frequency combs with hundreds of watts average output power.

  10. Narrow-line, tunable, high-power diode laser pump for DPAL applications (United States)

    Pandey, Rajiv; Merchen, David; Stapleton, Dean; Irwin, David; Humble, Chuck; Patterson, Steve; Kissel, Heiko; Biesenbach, Jens


    We report on a high-power diode laser pump source for diode-pumped alkali lasers (DPAL), specifically rubidium alkali vapor lasers at 780nm, delivering up to 100W/bar with FWHM spectral line width of 0.06nm (~30GHz). This pump is based on a micro-channel water-cooled stack with collimation in both-axes. Wavelength-locking of the output spectrum allows absorption in one of the very narrow resonance lines of the atomic rubidium alkali vapor. To achieve these results, research was conducted to deliver the highest performance on all key components of the product from the diode laser bar which produces the optical power at 780nm to the external Bragg gratings which narrow the spectrum line width. We highlight the advancements in the epitaxy, device design, beam collimation, grating selection, alignment, tunability and thermal control that enable realization of this novel pump-source for DPALs. Design trade-offs will be presented.

  11. Flashlamp pumped Ti-sapphire laser for ytterbium glass chirped pulse amplification

    Energy Technology Data Exchange (ETDEWEB)

    Nishimura, Akihiko; Ohzu, Akira; Sugiyama, Akira [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment] [and others


    A flashlamp pumped Ti:sapphire laser is designed for ytterbium glass chirped pulse amplification. A high quality Ti:sapphire rod and a high energy long pulse discharging power supply are key components. The primary step is to produce the output power of 10 J per pulse at 920 nm. (author)

  12. Picosecond pulse generation from a synchronously pumped mode-locked semiconductor laser diode (United States)

    Auyeung, J. C.; Johnston, A. R.


    A semiconductor laser diode was mode locked in an external cavity when synchronously pumped with 90-ps current pulses. Transform-limited optical pulses with a 10-ps pulse width and a peak power of 160 mW were produced. Operating characteristics of such a system are described.

  13. A kinetic model of the electron-beam-pumped XeCl laser active medium

    Energy Technology Data Exchange (ETDEWEB)

    Boichenko, A.M.; Derzhiev, V.I.; Zhidkov, A.G.; Iakovlenko, S.I. (Institut Obshchei Fiziki, Moscow (USSR))


    Kinetic models are developed for XeCl laser active media in different buffer gases (helium, neon, and argon) pumped by an electron beam. In the calculations of the generation characteristics, allowance is made for the effect of the cavity field on the photoinduced transitions. The numerical results on the efficiency are in good agreement with experiments on electron beams. 17 refs.

  14. Grazing Incidence Pumping X-Ray Laser Scheme with Application of Paraboloid Mirrors

    Institute of Scientific and Technical Information of China (English)

    DONG Quan-Li; YAN Fei; ZHANG Jie; ZHONG Jia-Yong; ZHAO Jing; SHENG Zheng-Ming; LI Han-Ming; LI Ying-Jun


    @@ A grazing incidence pumping x-ray laser scheme using JIGUANG Ⅱ is proposed. We investigate the characteristics of the focusing of parabolas, and obtain the optimal intensity distributions in the target surfaces with paraboloid mirrors of different parameters by the vectorial ray-tracing.

  15. Locking of self-oscillation frequency by pump modulation in an erbium-doped fiber laser (United States)

    Pisarchik, A. N.; Barmenkov, Yu. O.


    Frequency locking of self-oscillations in a diode-pumped erbium-doped fiber laser by external modulation of the diode current is studied experimentally. The coexistence of locking and unlocking regimes is detected. The condition for onset of the bistability and dependences of the frequency detuning on the modulation frequency and amplitude are established. Transitions to torus-chaos are also demonstrated.

  16. Simulation of a tunable optically pumped terahertz intersubband laser with diluted magnetic semiconductors

    NARCIS (Netherlands)

    Popadić, M.; Milanović, V.; Ikonić, Z.; Indijn, D.


    A simulation of an optically pumped laser based on a ZnSe/Zn1−yCdySe double quantum well with a Zn1−xMnxSe diluted magnetic semiconductor barrier is presented. Giant Zeeman splitting in diluted magnetic semiconductors leads to splitting of electronic states, which in turn leads to tunability of lase

  17. New class of compact diode pumped sub 10 fs lasers for biomedical applications

    DEFF Research Database (Denmark)

    Le, T.; Mueller, A.; Sumpf, B.;


    Diode-pumping Ti: sapphire lasers promises a new approach to low-cost femtosecond light sources. Thus in recent years much effort has been taken just to overcome the quite low power and low beam qualities of available green diodes to obtain output powers of several hundred milliwatts from a fs-la...

  18. Diode-side-pumped, passively Q-switched Yb:LuAG laser (United States)

    Kaskow, Mateusz; Galecki, Lukasz; Jabczynski, Jan K.; Skorczakowski, Marek; Zendzian, Waldemar; Sulc, Jan; Nemec, Michal; Jelinkova, Helena


    A high-gain, diode-side-pumped Yb:LuAG slab laser was designed and investigated for use at room temperature. Pumping occurred from a fast-axis collimated 2D laser diode stack emitting at a wavelength of 970 nm, with 0.8 J over a duration of 0.8 ms. The pump scheme, which enabled efficient mode matching and high gain, was analysed and experimentally verified for different dopant levels. An energy of 100 mJ with 23% slope efficiency in a near fundamental mode was achieved in the free-running regime. A peak power of 2.5 MW and a pulse energy of 10.1 mJ were demonstrated in passive Q-switching by means of a Cr:YAG saturable absorber with 39% initial transmission. The study defined the indications for optimizing such a system.

  19. End-pumped 1.5 microm monoblock laser for broad temperature operation. (United States)

    Schilling, Bradley W; Chinn, Stephen R; Hays, A D; Goldberg, Lew; Trussell, C Ward


    We describe a next-generation monoblock laser capable of a greater than 10 mJ, 1.5 microm output at 10 pulses/s (pps) over broad ambient temperature extremes with no active temperature control. The transmitter design is based on a Nd:YAG laser with a Cr4+ passive Q switch and intracavity potassium titanyl phosphate optical parametric oscillator. To achieve the repetition rate and efficiency goals of this effort, but still have wide temperature capability, the Nd:YAG slab is end pumped with a 12-bar stack of 100 W (each) diode bars. Different techniques for focusing the pump radiation into the 4.25 mmx4.25 mm end of the slab are compared, including a lensed design, a reflective concentrator, and a lens duct. A wide temperature operation (-20 degrees C to 50 degrees C) for each end-pumped configuration is demonstrated.

  20. Pre-pumped passively Q-switched Nd:YAG/Cr:YAG microchip laser

    Institute of Scientific and Technical Information of China (English)

    Xinning Tian(田信宁); Ping Yan(闫平); Qiang Liu(柳强); Mali Gong(巩马理); Yun Liao(廖云)


    A pre-pumped passively Q-switched Nd:YAG/Cr:YAG microchip laser is demonstrated with a peak power of 7.5 kW at pulse repetition rate of serveral kilohertzs. The full-width at half-maximum(FWHM)is 734 ps, and the pulse energy is 5.5 μJ with a fundamental spatial mode. In this system, the pre-pumped microchip laser of Nd:YAG/Cr:YAG wafer which is bonded through the thermal-bonding technique has achieved a time jitter value of 12 μs and a Q-switched amplitude instability of 1.26%(15)through the pre-pumped modulation technique.

  1. An optically pumped GaN/AlGaN quantum well intersubband terahertz laser (United States)

    Fu, Ai-Bing; Hao, Ming-Rui; Yang, Yao; Shen, Wen-Zhong; Liu, Hui-Chun


    We propose an optically pumped nonpolar GaN/AlGaN quantum well (QW) active region design for terahertz (THz) lasing in the wavelength range of 30 μm ~ 40 μm and operating at room temperature. The fast longitudinal optical (LO) phonon scattering in GaN/AlGaN QWs is used to depopulate the lower laser state, and more importantly, the large LO phonon energy is utilized to reduce the thermal population of the lasing states at high temperatures. The influences of temperature and pump intensity on gain and electron densities are investigated. Based on our simulations, we predict that with a sufficiently high pump intensity, a room temperature operated THz laser using a nonpolar GaN/AlGaN structure is realizable.

  2. The ISOLDE RILIS pump laser upgrade and the LARIS Laboratory

    CERN Document Server

    Marsh, B A; Fedorov, D V; Fedosseev, V N; Launila, O J; Lindroos, M; Losito, R; Osterdahl, F K; Pauchard, T; Pohjalainen, I T; Sassenberg, U; Seliverstov, M DSt. Petersburg, INP; Sjödin, A M; Tranströmer, G


    On account of its high efficiency, speed and unmatched selectivity, the Resonance Ionization Laser Ion Source (RILIS) is the preferred method for ionizing the nuclear reaction products at the ISOLDE on-line isotope separator facility. [...

  3. Pump Diode Characterization for an Unstable Diode-Pumped Alkali Laser Resonator (United States)


    narrowed linewidth. Learning how to control the tuning range of the VBG will permit the fine-tuning of the output frequency of the pump to match the...of commands and their descriptions HINDI get/set toggle indicators on/off HMODEL get harmonic model HO get/set harmonic options HQ get has Q‐switch

  4. Theoretical analysis of thermal effects in fiber laser from the moment when pump is turned on to steady-state

    Institute of Scientific and Technical Information of China (English)

    Zilun Chen; Jing Hou; Zongfu Jiang


    A theoretical analysis of the pump-induced temperature change and associated thermal phase shift occurring in a fiber laser is presented. The temperature rise and thermal phase shift from the moment when pump is turned on to steady-state in fiber lasers, such as Yb-doped fiber laser, are numerical calculated.With the same parameters, the numerical solution is in good agreement with the finite-element (ANSYS software) simulation.

  5. Rate equations model and optical external efficiency of optically pumped electrically driven terahertz quantum cascade lasers (United States)

    Hamadou, A.; Thobel, J.-L.; Lamari, S.


    A four level rate equations model for a terahertz optically pumped electrically driven quantum cascade laser is here introduced and used to model the system both analytically and numerically. In the steady state, both in the presence and absence of the terahertz optical field, we solve the resulting nonlinear system of equations and obtain closed form expressions for the levels occupation, population inversion as well as the mid-infrared pump threshold intensity in terms of the device parameters. We also derive, for the first time for this system, an analytical formula for the optical external efficiency and analyze the simultaneous effects of the cavity length and pump intensity on it. At moderate to high pump intensities, we find that the optical external efficiency scales roughly as the reciprocal of the cavity length.

  6. OLET architectures for electrically-pumped organic lasers (United States)

    Zamboni, R.; Capelli, R.; Toffanin, S.; Murgia, M.; Först, M.; Muccini, M.


    Organic light emitting transistors (OLET) have been recently demonstrated as innovative architectures combining into an integrated optoelectronic device multi-functional properties namely, the driving ability of a transistor device with the conversion of electrical current into efficient light emission via electronic relaxation of organic semiconductors. State of the art materials, achievement and performances will be presented and discussed in view of possible OLET architectures exploitation as electrically pumped organic nanolasers.

  7. An Optical Cryostat with $^{3}$He Sorption Refrigerator

    CERN Document Server

    Trofimov, V N; Perminov, V G; Vdovin, V F; Vystavkin, A N


    An optical cryostat with $^{3}$He sorption refrigerator is described. The refrigerator is mounted on a copper plate with temperature 4.2 K in vacuum volume of a helium cryostat. It has two sorption steps: the first with working gas $^4$He is intended for condensation of $^{3}$He, the second with $^{3}$He for cooling down to 0.3 K. The cryostat is an independent device that does not contain the external gas communications aimed at reaching low temperatures, and working gases are stored in cans integrated with the cryostat. The refrigerator can be used together with the cryocoolers of Gifford--McMahon or pulse tube types with cooling power not less than 0.3 W/4 K, thus allowing operating without any liquid cryoagents.

  8. Strong-Coupling and the Stripe Phase of ^3He (United States)

    Wiman, Joshua J.; Sauls, J. A.


    Thin films of superfluid 3He were predicted, based on weak-coupling BCS theory, to have a stable phase which spontaneously breaks translational symmetry in the plane of the film. This crystalline superfluid, or "stripe" phase, develops as a one-dimensional periodic array of domain walls separating degenerate B phase domains. We report calculations of the phases and phase diagram for superfluid 3He in thin films using a strong-coupling Ginzburg-Landau theory that accurately reproduces the bulk 3He superfluid phase diagram. We find that the stability of the Stripe phase is diminished relative to the A phase, but the Stripe phase is stable in a large range of temperatures, pressures, confinement, and surface conditions.

  9. Recurring 3He-rich Solar Energetic Particle Events

    CERN Document Server

    Bucik, R; Mall, U; Korth, A; Mason, G M


    Using the SIT instrument aboard STEREO we have examined the abundance of the 3He during the ascending phase of solar cycle 24 from January 2010 through December 2012. We report on several cases when 3He-rich solar energetic particle events were successively observed on ACE and STEREO-A with delays consistent with the Carrington rotation rate. In the investigated period ACE and STEREO-A were significantly separated in the heliolongitude corresponding to solar rotation times of 5 to 10 days. We inspect STEREO-A EUV images and use the potential-field source-surface extrapolations together with in-situ magnetic field data to identify responsible solar sources. We find the 3He/4He ratio highly variable in these events and correlated between the spacecraft for the cases with the same connection region on the Sun.

  10. Light-Front Dynamics and the 3He Spectral Function

    CERN Document Server

    Pace, Emanuele; Kaptari, Leonid; Rinaldi, Matteo; Salme', Giovanni; Scopetta, Sergio


    Two topics are presented. The first one is a novel approach for a Poincare' covariant description of nuclear dynamics based on light-front Hamiltonian dynamics. The key quantity is the light-front spectral function, where both normalization and momentum sum rule can be satisfied at the same time. Preliminary results are discussed for an initial analysis of the role of relativity in the EMC effect in 3He. A second issue, very challenging, is considered in a non-relativistic framework, namely a distorted spin-dependent spectral function for 3He in order to take care of the final state interaction between the observed pion and the remnant in semi-inclusive deep inelastic electron scattering off polarized 3He. The generalization of the analysis within the light-front dynamics is outlined.

  11. Quark-Hadron Duality in Neutron (3He) Spin Structure

    Energy Technology Data Exchange (ETDEWEB)

    Solvignon, Patricia; Liyanage, Nilanga; Chen, Jian-Ping; Choi, Seonho; Aniol, Konrad; Averett, Todd; Boeglin, Werner; Camsonne, Alexandre; Cates, Gordon; Chang, C.; Chang, C.C.; Chang, C.; Chang, C.C.; Chudakov, Eugene; Craver, Brandon; Cusanno, Francesco; Deur, Alexandre; Dutta, Dipangkar; Ent, Rolf; Feuerbach, Robert; Frullani, Salvatore; Gao, Haiyan; Garibaldi, Franco; Gilman, Ronald; Glashausser, Charles; Gorbenko, Viktor; Hansen, Jens-Ole; Higinbotham, Douglas; Ibrahim, Hassan; Jiang, Xiaodong; Jones, Mark; Kelleher, Aidan; Kelly, J.; Keppel, Cynthia; Kim, Wooyoung; Korsch, Wolfgang; Kramer, Kevin; Kumbartzki, Gerfried; LeRose, John; Lindgren, Richard; Ma, Bin; Margaziotis, Demetrius; Markowitz, Pete; McCormick, Kathy; Meziani, Zein-Eddine; Michaels, Robert; Moffit, Bryan; Monaghan, Peter; Munoz-Camacho, Carlos; Paschke, Kent; Reitz, Bodo; Saha, Arunava; Sheyor, Ran; Singh, Jaideep; Slifer, Karl; Sulkosky, Vince; Sulkosky, Vincent; Sulkosky, Vince; Sulkosky, Vincent; Tobias, William; Urciuoli, Guido; Wang, Kebin; Wijesooriya, Krishni; Wojtsekhowski, Bogdan; Woo, Seungtae; Yang, Jae-Choon; Zheng, Xiaochao; Zhu, Lingyan


    We present experimental results of the first high-precision test of quark-hadron duality in the spin-structure function g_1 of the neutron and $^3$He using a polarized 3He target in the four-momentum-transfer-squared range from 0.7 to 4.0 (GeV/c)^2. Global duality is observed for the spin-structure function g_1 down to at least Q^2 = 1.8 (GeV/c)^2 in both targets. We have also formed the photon-nucleon asymmetry A_1 in the resonance region for 3He and found no strong Q^2-dependence above 2.2 (GeV/c)^2.

  12. Quark-Hadron Duality in Neutron (3He) Spin Structure

    CERN Document Server

    Solvignon, P; Chen, J -P; Choi, Seonho; Aniol, K; Averett, T; Boeglin, W; Camsonne, A; Cates, G D; Chang, G; Chudakov, E; Craver, B; Cusanno, F; Deur, A; Dutta, D; Ent, R; Feuerbach, R; Frullani, S; Gao, H; Garibaldi, F; Gilman, R; Glashausser, C; Gorbenko, V; Hansen, O; Higinbotham, D W; Ibrahim, H; Jiang, X; Jones, M; Kelleher, A; Kelly, J; Keppel, C; Kim, W; Korsch, W; Krämer, K; Kumbartzki, G; LeRose, J J; Lindgren, R; Ma, B; Margaziotis, D J; Markowitz, P; McCormick, K; Meziani, Z -E; Michaels, R; Moffit, B; Monaghan, P; Camacho, C Munoz; Paschke, K; Reitz, B; Saha, A; Sheyor, R; Singh, J; Slifer, K; Sulkosky, V; Tobias, A; Urciuoli, G M; Wang, K; Wijesooriya, K; Wojtsekhowski, B; Woo, S; Yang, J -C; Zheng, X; Zhu, L


    We present experimental results of the first high-precision test of quark-hadron duality in the spin-structure function g_1 of the neutron and $^3$He using a polarized 3He target in the four-momentum-transfer-squared range from 0.7 to 4.0 (GeV/c)^2. Global duality is observed for the spin-structure function g_1 down to at least Q^2 = 1.8 (GeV/c)^2 in both targets. We have also formed the photon-nucleon asymmetry A_1 in the resonance region for 3He and found no strong Q^2-dependence above 2.2 (GeV/c)^2.

  13. Evolution of D and $^{3}He$ in the Galaxy

    CERN Document Server

    Tosi, M P


    The predictions of Galactic chemical evolution models for D and $^3$He are described in connection with those on the other Galactic quantities for which observational constraints are available. Models in agreement with the largest set of data predict deuterium depletions from the Big Bang to the present epoch smaller than a factor of 3 and do not allow for D/H primordial abundances larger than $\\sim4\\times10^{-5}$. Models predicting higher D consumption do not reproduce other observed features of our Galaxy. If both the primordial D and $^3$He are low, models assuming that 90% of low-mass stars experience an extra-mixing during the red giant phase reproduce all the $^3$He observed abundances. The same percentage allows to fit also the observed carbon isotopic ratios, thus supporting the self-consistency of the extra-mixing mechanism.

  14. Feasibility of neutron diffraction on solid 3He (United States)

    Siemensmeyer, K.; Schuberth, E. A.; Adams, E. D.; Takano, Y.; Guckelsberger, K.


    We have investigated the feasibility of neutron diffraction from solid 3He. The experiment will be performed at the HMI, first aiming for the properties of the antiferromagnetic ordering in the BCC phase and the ferromagnetic order in the HCP phase. Signal and beam heating considerations are essential to account for the enormous neutron absorption cross section of 3He. The study shows that neutron diffraction and transmission experiments are possible, relying on the experience gained from the neutron diffraction experiments on Cu and Ag at nanokelvin temperatures. A pressure cell has been developed which complies with the conflicting demands arising from the neutron and ultralow temperature aspects of the experiment. This work is a first step in an extensive effort to characterize 3He by neutron diffraction.

  15. Synchronously pumped picosecond all-fibre Raman laser based on phosphorus-doped silica fibre. (United States)

    Kobtsev, Sergey; Kukarin, Sergey; Kokhanovskiy, Alexey


    Reported for the first time is picosecond-range pulse generation in an all-fibre Raman laser based on P₂O₅-doped silica fibre. Employment of phosphor-silicate fibre made possible single-cascade spectral transformation of pumping pulses at 1084 nm into 270-ps long Raman laser pulses at 1270 nm. The highest observed fraction of the Stokes component radiation at 1270 nm in the total output of the Raman laser amounted to 30%. The identified optimal duration of the input pulses at which the amount of Stokes component radiation in a ~16-m long phosphorus-based Raman fibre converter reaches its maximum was 140-180 ps.

  16. Side-pumped short rectangular Nd-doped phosphate glass fiber lasers

    Institute of Scientific and Technical Information of China (English)

    Yulong Tang; Yong Yang; Jianqiu Xu


    Watt-level short fiber lasers side-pumped through fiber-to-waveguide couplers are demonstrated. The fiber lasers are fabricated from Nd-doped phosphate glass with large numerical aperture of 0.2 and rectangular cross section of 1.5 × 0.5 (mm). Single transverse mode output is achieved by the gain-guiding effect. Average power of 1 W is generated from a 4.0-cm-long fiber laser with a slope efficiency of 10%.

  17. High-Power Diode-Side-Pumped Intracavity-Frequency-Doubled Continuous Wave 532 nm Laser

    Institute of Scientific and Technical Information of China (English)

    ZHANG Yu-Ping; ZHANG Hui-Yun; ZHONG Kai; LI Xi-Fu; WANG Peng; YAO Jian-Quan


    @@ An efficient and high-power diode-side-pumped cw 532nm green laser based on a V-shaped cavity geometry, and capable of generating 22.7 W green radiation with optical conversion efficiency of 8.31%, has been demonstrated. The laser is operated with rms noise amplitude of less than 1% and with M2-parameter of about 6.45 at the top of the output power. This laser has the potential for scaling to much higher output power.

  18. Design of a device for pumping a double-clad fiber laser with a laser-diode bar. (United States)

    Zenteno, L A


    Pumping rare-earth-doped double-clad fiber lasers with GaAlAs laser-diode bars typically requires one to transform a 1-cm-long one-dimensional linear array of tens of multimode laser-diode sources into atwo-dimensional oblong cross section that approximately matches the fiber's first cladding shape. I describe the design of a device, henceforth called a high-brightness geometric transformer, that uses a cylindrical microlens to image the laser-diode bar near field onto a linear array of soft-glass, thin-clad, rectangular fibers. In turn, the fibers output ends are arranged to form a stack that matches the required first cladding shape. For a typical laser-diode bar with a brightness of 25 mW·µm(-2)·sr(-1), the geometric transformer output brightness is 0.6 mW·µm(-2)·sr(-1), i.e., there is a 40× intermediate loss of brightness. If the output of the geometric transformer is used to pump a Nd-doped double-clad fiber laser, anoverall brightness gain of 340× can be achieved.

  19. Novel pressure sensor by diode-pumped birefringent Nd:YAG dual-frequency laser (United States)

    Huang, Chunning; Li, Yan; Zhang, Shulian; Guo, Hui


    The prototype of a novel sensor based on laser frequency splitting technology is presented in this paper and the results of a series of experiments are reported. A scheme of the novel pressure sensor by diode-pumped birefringent Nd:YAG dual-frequency laser is brought forward. As a result of the stress birefringence the laser's longitudinal mode is split to two with frequency difference. Both the theoretical analysis and the experiments indicate that there is a direct ratio relation between the frequency difference and the pressure imposed on the Nd:YAG crystal. Therefore when the external pressure is sensed by the Nd:YAG dual-frequency laser and the beat frequency is measured by the frequency counter, the pressure value can be obtained from the magnitude of the beat frequency. The laser can operate under single mode or complex modes with little error to the experiment results. Some research work under different pumping ways is finished and it indicates that the beat frequency has little relation with pumping ways. The experiment has a good linearity (R greater than 0.999) with satisfied precision, sensitivity (5.27 MHz/kPa) and stability, which provides a good academic and experimental foundation for further research.

  20. Development of solar concentrators for high-power solar-pumped lasers. (United States)

    Dinh, T H; Ohkubo, T; Yabe, T


    We have developed unique solar concentrators for solar-pumped solid-state lasers to improve both efficiency and laser output power. Natural sunlight is collected by a primary concentrator which is a 2  m×2  m Fresnel lens, and confined by a cone-shaped hybrid concentrator. Such solar power is coupled to a laser rod by a cylinder with coolant surrounding it that is called a liquid light-guide lens (LLGL). Performance of the cylindrical LLGL has been characterized analytically and experimentally. Since a 14 mm diameter LLGL generates efficient and uniform pumping along a Nd:YAG rod that is 6 mm in diameter and 100 mm in length, 120 W cw laser output is achieved with beam quality factor M2 of 137 and overall slope efficiency of 4.3%. The collection efficiency is 30.0  W/m2, which is 1.5 times larger than the previous record. The overall conversion efficiency is more than 3.2%, which can be comparable to a commercial lamp-pumped solid-state laser. The concept of the light-guide lens can be applied for concentrator photovoltaics or other solar energy optics.

  1. Neutron-scattering experiment on solid 3He (United States)

    Mat'aš, S.; Bat'ko, I.; Boyko, V.; Schöttl, S.; Siemensmeyer, K.; Raasch, S.; Radulov, I.; Adams, E. D.; Scherline, T. E.

    The central aim of our work is the characterisation of magnetic and crystallographic properties of solid 3He on a microscopic scale. This can only be achieved using neutron-diffraction techniques. The potential of neutron methods in magnetism and their application to nuclear magnetism is well known. They were very successful in the recent investigation of spontaneous nuclear order in copper and silver. The high neutron absorption cross section makes the application of neutron diffraction in solid 3He very difficult - but a careful feasibility study of diffraction experiments shows that new results of fundamental importance in the field of magnetism may be gained.

  2. Anisotropic phases of superfluid ^{3}he in compressed aerogel. (United States)

    Li, J I A; Zimmerman, A M; Pollanen, J; Collett, C A; Halperin, W P


    It has been shown that the relative stabilities of various superfluid states of ^{3}He can be influenced by anisotropy in a silica aerogel framework. We prepared a suite of aerogel samples compressed up to 30% for which we performed pulsed NMR on ^{3}He imbibed within the aerogel. We identified A and B phases and determined their magnetic field-temperature phase diagrams as a function of strain. From these results, we infer that the B phase is distorted by negative strain forming an anisotropic superfluid state more stable than the A phase.

  3. Optimized Biasing of Pump Laser Diodes in a Highly Reliable Metrology Source for Long-Duration Space Missions (United States)

    Poberezhskiy, Ilya Y; Chang, Daniel H.; Erlig, Herman


    Optical metrology system reliability during a prolonged space mission is often limited by the reliability of pump laser diodes. We developed a metrology laser pump module architecture that meets NASA SIM Lite instrument optical power and reliability requirements by combining the outputs of multiple single-mode pump diodes in a low-loss, high port count fiber coupler. We describe Monte-Carlo simulations used to calculate the reliability of the laser pump module and introduce a combined laser farm aging parameter that serves as a load-sharing optimization metric. Employing these tools, we select pump module architecture, operating conditions, biasing approach and perform parameter sensitivity studies to investigate the robustness of the obtained solution.

  4. Modeling of end-pumped Yb:YAG thin-disk lasers with nonuniform temperature distribution. (United States)

    Zhu, Guangzhi; Zhu, Xiao; Zhu, Changhong; Shang, Jianli; Wan, Hailin; Guo, Fei; Qi, Lijun


    A plane wave model with nonuniform temperature distribution in the thin-disk crystal is developed to describe the dynamic behavior of an end-pumped Yb:YAG thin-disk laser. A set of couple-rate equations and 2D stationary heat-conduction equations are derived. The stable temperature distribution in the disk crystal is calculated using a numerical iterative method. The analytic expression is capable of dealing with more practical laser systems than previous works on this subject as it allows for nonuniform temperature distribution in the disk crystal. Based on these results, we examined laser output intensity as a function of pump intensity, dopant concentration, resonator coupler reflectivity, crystal thickness and temperature of cooling liquid.

  5. yb3+-Doped Double-Clad Fibre Laser Pumped by Rectangular Inner Cladding

    Institute of Scientific and Technical Information of China (English)

    宁鼎; 李乙刚; 黄榜才; 孙建军; 吕可诚; 袁树忠; 董孝义


    A novel Yb3+-doped double-clad silica fibre with rectangular inner cladding was designed and developed by using the modified chemical vapour deposition process, solution-doping and optical machining all together. The dimensions of the inner cladding are 100 × 70 μm, and Yb3+-doped concentration in the core is about 0.24 wt. %. The operation of the fibre laser pumped by inner cladding is reported. The threshold of the laser is 34mW.When the pump power launched is 141mW, the laser output is 84mW at the wavelength 1075.6nm, and the slope efficiency is 77%.

  6. Multi-coupler side-pumped Yb-doped double-clad fiber laser

    Institute of Scientific and Technical Information of China (English)

    Pan Ou(欧攀); Ping Yan(闫平); Mali Gong(巩马理); Wenlou Wei(韦文楼)


    The side-coupler of angle polished method, using angle-polished multimode fiber and optical adhesive, is used to efficiently pump an Yb-doped double-clad fiber laser. The maximum coupling efficiency of 78.6% is achieved by the side-coupler for a multimode fiber with a circular core of 200 μm and a double-clad fiber with a 350/400 μm D-shaped inner cladding. While laser diodes (LDs) with three side-couplers are simultaneously used as pump sources, maximum output power of 1.38 W and slope efficiency of 48.9% are demonstrated in the fiber laser system.

  7. Multi-coupler side-pumped Yb-doped double-clad fiber laser

    Institute of Scientific and Technical Information of China (English)

    欧攀; 闫平; 巩马理; 韦文楼


    The side-coupler of angle polished method, using angle-polished multimode fiber and optical adhesive, is used to efficiently pump an Yb-doped double-clad fiber laser. The maximum coupling efficiency of 78.6%is achieved by the side-coupler for a multimode fiber with a circular core of 200 μm and a double-clad fiber with a 350/400 μm D-shaped inner cladding. While laser diodes (LDs) with three side-couplers are simultaneously used as pump sources, maximum output power of 1.38 W and slope efficiency of 48.9% are demonstrated in the fiber laser system.

  8. A Continuous-Wave Diode-Side-Pumped Tm:YAG Laser with Output 51 W

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xiao-Fu; CUI DaFu; XU Zu-Yan; XU Yi-Ting; LI Cheng-Ming; ZONG Nan; XU Jia-Lin; CUI Qian-Jin; LU Yuan-Fu; BO Yong; PENG Qin-Jun


    A compact diode-side-pumped Tm:YAG laser is presented, which can output 51 W of cw power at 2.02μm. The Tm:YAG rod is side pumped by nine diode arrays with the central wavelength of 783nm and the with bandwidth of about 2.5 nm at 25℃. To decrease the thermal effect on the both ends and dissipate the heat effectively, one composite Tm:YAG rod with the undoped YAG end caps and the screw threads on the side surface of the rod is used as the laser crystal. The maximum optical-to-optical conversion efficiency of the 2.02-μm laser output is 14.2%, with a slope efficiency of 26.8%.

  9. Study of diode-pumped Yb:YAG disk lasers at low temperature

    Institute of Scientific and Technical Information of China (English)

    Jianlei Wang; Zhenhua Zhang; Xiaojin Cheng; Lei Li; Xiangchun Shi; Xiaolei Zhu; Weibiao Chen


    A Yb:YAG disk laser with V-shaped stable resonator and active-mirror configuration, end-pumped by a 940-nm InGaAs laser diode array, is demonstrated. Performances and optimization of the disk laser at low temperature over a range of 130-200 K are investigated theoretically and experimentally. Laser output energy of 1.46 J/pulse operating at 10-Hz repetition rate is obtained with the optimum output coupler transmission of 30%, and the corresponding optical-to-optical efficiency is 48.7%.%Yb:YAG[1-4],by virtue of its high quantum efficiency (>90%),long life time,no concentration quenching,no excite-state absorption,and no upconversion effect,has recently been considered as a suitable candidate for lasers with high average power and high efficiency[5-7].Due to their wide absorption band centered at 941 nm,Yb:YAG lasers are more acceptable for variation of pump laser diode (LD) wavelength.

  10. Low threshold and high efficiency solar-pumped laser with Fresnel lens and a grooved Nd:YAG rod (United States)

    Guan, Zhe; Zhao, Changming; Yang, Suhui; Wang, Yu; Ke, Jieyao; Gao, Fengbin; Zhang, Haiyang


    Sunlight is considered as a new efficient source for direct optical-pumped solid state lasers. High-efficiency solar pumped lasers with low threshold power would be more promising than semiconductor lasers with large solar panel in space laser communication. Here we report a significant advance in solar-pumped laser threshold by pumping Nd:YAG rod with a grooved sidewall. Two-solar pumped laser setups are devised. In both cases, a Fresnel lens is used as the primary sunlight concentrator. Gold-plated conical cavity with a liquid light-guide lens is used as the secondary concentrator to further increase the solar energy concentration. In the first setup, solar pumping a 6mm diameter Nd:YAG rod, maximum laser power of 31.0W/m2 cw at 1064nm is produced, which is higher than the reported record, and the slope efficiency is 4.98% with the threshold power on the surface of Fresnel lens is 200 W. In the second setup, a 5 mm diameter laser rod output power is 29.8W/m2 with a slope efficiency of 4.3%. The threshold power of 102W is obtained, which is 49% lower than the former. Meanwhile, the theoretical calculating of the threshold power and slope efficiency of the solar-pumped laser has been established based on the rate-equation of a four-level system. The results of the finite element analysis by simulation software are verified in experiment. The optimization of the conical cavity by TraceProsoftware and the optimization of the laser resonator by LASCADare useful for the design of a miniaturization solar- pumped laser.

  11. Efficient Pumping Schemes for High Average Brightness Collisional X-ray Lasers

    Energy Technology Data Exchange (ETDEWEB)

    Keenan, R; Dunn, J; Shlyaptsev, V N; Smith, R F; Patel, P K; Price, D F


    Advances in transient collisional x-ray lasers have been demonstrated over the last 5 years as a technique for achieving tabletop soft x-ray lasers using 2-10 J of laser pump energy. The high peak brightness of these sources operating in the high output saturation regime, in the range of 10{sup 24}-10{sup 25} ph. mm{sup -2} mrad{sup -2} s-1 (0.1% BW){sup -1}, is ideal for many applications requiring high photon fluence in a single short burst. However, the pump energy required for these x-ray lasers is still relatively high and limits the x-ray laser repetition rate to 1 shot every few minutes. Higher repetition rate collisional schemes have been reported and show some promise for high output in the future. We report a novel technique for enhancing the coupling efficiency of the laser pump into the gain medium that could lead to enhanced x-ray inversion with a factor of ten reduction in the drive energy. This has been applied to the collisional excitation scheme for Ni-like Mo at 18.9 nm and x-ray laser output has been demonstrated. Preliminary results show lasing on a single shot of the optical laser operating at 10 Hz and with 70 mJ in the short pulse. Such a proposed source would have higher average brightness, {approx}10{sup 14} ph. mm{sup -2} mrad{sup -2} s{sup -1} (0.1% BW){sup -1}, than present bending magnet 3rd generation synchrotron sources operating at the same spectral range.

  12. 1.8kW laser diode pumped YAG laser; Shutsuryoku 1.8kW no handotai laser reiki YAG laser

    Energy Technology Data Exchange (ETDEWEB)



    Toshiba Corporation, as a participant in Ministry of International Trade and Industry`s `photon measurement and processing technology project` since August, 1997, is engaged in the development of an energy-efficient LD (laser diode) pumped semiconductor YAG (yttrium-aluminum-garnet) laser device to be used for welding and cutting. It is a 5-year project and the goal is a mean output of 10kW and efficiency of 20%. In this article, a simulation program is developed which carries out calculation about element technology items such as the tracking of the beam from the pumping LD and the excitation distribution, temperature distribution, thermal stress distribution, etc., in the YAG rod. An oscillator is constructed, based on the results of the simulation, and it exhibits a world-high class continuous laser performance of a 1.8kW output and 13% efficiency. The record of 13% efficiency is five times higher than that achieved by the conventional lamp-driven YAG laser device. (translated by NEDO)

  13. Laser pumping of ions in a cooler buncher

    Energy Technology Data Exchange (ETDEWEB)

    Cheal, B., E-mail: [University of Manchester (United Kingdom); Baczynska, K. [University of Birmingham, School of Physics and Astronomy (United Kingdom); Billowes, J.; Campbell, P. [University of Manchester (United Kingdom); Eronen, T. [University of Jyvaeskylae, Department of Physics (Finland); Forest, D. H. [University of Birmingham, School of Physics and Astronomy (United Kingdom); Kessler, T.; Moore, I. D. [University of Jyvaeskylae, Department of Physics (Finland); Rueffer, M. [University of Birmingham, School of Physics and Astronomy (United Kingdom); Tordoff, B. [University of Manchester (United Kingdom); Tungate, G. [University of Birmingham, School of Physics and Astronomy (United Kingdom); Aystoe, J. [University of Jyvaeskylae, Department of Physics (Finland)


    Optical experiments at the IGISOL isotope separator facility, Jyvaeskylae, have for many years benefited from the introduction of an ion beam cooler. The device, a gas-filled RF quadrupole, reduces the emittance and longitudinal energy spread of the ion beam. Very recently, use has been made of the axial confinement of slowly travelling ions at the end of the cooler to redistribute the electronic populations through efficient laser excitation. Such a technique has proved beneficial to laser spectroscopic measurements and is a precursor to using the method to polarize the ion beam.

  14. Simulation of medical Q-switch flash-pumped Er:YAG laser

    Energy Technology Data Exchange (ETDEWEB)

    Wang Yanlin; Huang Chuyun; Yao Yucheng; Zou Xiaolin, E-mail:, E-mail:, E-mail:, E-mail: [Physics school, Hubei University of Technology, Wuhan, China 430068 (China)


    Er: YAG laser, the wavelength is 2940nm, can be absorbed strongly by water. The absorption coefficient is as high as 13000 cm{sup -1}. As the water strong absorption, Erbium laser can bring shallow penetration depth and smaller surrounding tissue injury in most soft tissue and hard tissue. At the same time, the interaction between 2940nm radiation and biological tissue saturated with water is equivalent to instantaneous heating within limited volume, thus resulting in the phenomenon of micro-explosion to removal organization. Different parameters can be set up to cut enamel, dentin, caries and soft tissue. For the development and optimization of laser system, it is a practical choice to use laser modeling to predict the influence of various parameters for laser performance. Aim at the status of low Erbium laser output power, flash-pumped Er: YAG laser performance was simulated to obtain optical output in theory. the rate equation model was obtained and used to predict the change of population densities in various manifolds and use the technology of Q-switch the simulate laser output for different design parameters and results showed that Er: YAG laser output energy can achieve the maximum average output power of 9.8W under the given parameters. The model can be used to find the potential laser systems that meet application requirements.

  15. Neutron spin filter based on optically polarized sup 3 He in a near-zero magnetic field

    CERN Document Server

    Skoy, V R; Sorokin, V N; Kolachevsky, N N; Sobelman, I I; Sermyagin, A V


    A test of polarization of sup 3 He nuclei via spin-exchange collisions with optically pumped rubidium atoms in an extremely low applied magnetic field was carried out. Permalloy magnetic shields were used to prevent a fast relaxation of sup 3 He polarization owing to the inhomogeneity of a surrounding magnetic field. The whole installation was placed at the neutron beam line of the IBR-30 facility, and used as a neutron spin filter. Thus, a prototype of new design of neutron polarizer was introduced. We intend to apply this experience for the full-scale KaTRIn facility to test the time reversal violation in neutron-nuclear reactions.

  16. Neutron spin filter based on optically polarized {sup 3}He in a near-zero magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Skoy, V.R. E-mail:; Prokofichev, Yu.V.; Sorokin, V.N.; Kolachevski, N.N.; Sobelman, I.I.; Sermyagin, A.V


    A test of polarization of {sup 3}He nuclei via spin-exchange collisions with optically pumped rubidium atoms in an extremely low applied magnetic field was carried out. Permalloy magnetic shields were used to prevent a fast relaxation of {sup 3}He polarization owing to the inhomogeneity of a surrounding magnetic field. The whole installation was placed at the neutron beam line of the IBR-30 facility, and used as a neutron spin filter. Thus, a prototype of new design of neutron polarizer was introduced. We intend to apply this experience for the full-scale KaTRIn facility to test the time reversal violation in neutron-nuclear reactions.

  17. Conceptual design of a polarized 3He neutron spin filter for polarized neutron spectrometer POLANO at J-PARC (United States)

    Ino, T.; Ohoyama, K.; Yokoo, T.; Itoh, S.; Ohkawara, M.; Kira, H.; Hayashida, H.; Sakai, K.; Hiroi, K.; Oku, T.; Kakurai, K.; Chang, L. J.


    A 3He neutron spin filter (NSF) has been designed for a new polarized neutron chopper spectrometer called the Polarization Analysis Neutron Spectrometer with Correlation Method (POLANO) at the Materials and Life Science Experimental Facility of the Japan Proton Accelerator Research Complex. It is designed to fit in a limited space on the spectrometer as an initial neutron beam polarizer and is polarized in situ by spin exchange optical pumping. This will be the first generation 3He NSF on POLANO, and a polarized neutron beam up to 100 meV with a diameter of 50 mm will be available for research on magnetism, hydrogen materials, and strongly correlated electron systems.

  18. Laser Characteristics of Cladding-Pumped Short Er3+/yb3+ Codoped Single Mode Phosphate Glass Fibre

    Institute of Scientific and Technical Information of China (English)

    XU Shan-Hui; YANG Zhong-Min; XU Wen-Cheng; QIU Dong-Lai; ZHANG Qin-Yuan; JIANG Zhong-Hong


    We experimentally investigate the laser characteristics of a ser/es of short pieces of newly-developed Er3+/Yb3+ codoped single mode phosphate glass fibres via the cladding pump of a 976nm multimode laser diode. A stable continuous-wave single transverse mode laser with over 85 m W at 1553 nm is generated from a 5.5-cm-long active fibre. Single mode laser output power per unit length is up to 15 m W/cm. Moreover, the slope efficiency is 11.8% when the pump power is below 940mW and the 3dB linewidth is 0.06nm at the maximum pump power. The numerical simulation results show that the laser emission slope efficiency can exceed 20% by means of increasing the coupling efficiency of the pump to the fibre core further.

  19. Analysis of dual-end-pumped Nd3+-doped index-crossover gain guided-index antiguided fiber laser (United States)

    Shen, Xiao; Wei, Wei; Zou, Hui; Zhang, Liaolin


    A dual-end pumped Nd3+-doped index-crossover gain guided-index antiguided (IGG-IAG) fiber laser is analyzed in theory. Pump light propagation and output laser characteristics are both explored by solving the related rate equations. Simulation results show that pump power confined in the IGG-IAG fiber core is larger and more uniform than that of the gain-guided and index-antiguided(GG-IAG) fiber, and the optimum fiber length and the output power of the IGG-IAG fiber laser are both larger than that of GG-IAG fiber laser. The relationship between threshold pump power and doped concentration, fiber length, fiber radius is researched respectively. The analysis results give out a method for the optimal design of the IGG-IAG fiber laser.

  20. Efficient Laser-Diode End-Pumped Passively Q-Switched Mode-Locked Yb:LYSO Laser Based on SESAM

    Institute of Scientific and Technical Information of China (English)

    XU Shi-Xiang; LI Wen-Xue; HAO Qiang; ZHAI Hui; ZENG He-Ping


    We report an eddicient Q-switched laser action based on a semiconductor saturable absorber mirrors(SESAMs)as passively Q-switched laser starter and a Yb:LYSO alloyed crystal as gain material pumped directly by 974nm In GaAs laser diodes.The output pulse duration is measured to be about 7μs,while the average power and the repetition rate of the pulse chain are about 0.92 W and 6.2kHz.respectively,under 12.5 W absorbed pumping power.The Q-switched mode-locked pulse train is also observed in this setup.The laser performance shows that Yb:LYSO is a promising laser gain medium for laser-diode pumped compact solid-state lasers.

  1. Three dimensional structural insight of laser drilled orifices in osmotic pump tablets. (United States)

    Wu, Li; Wang, Lebing; Wang, Shuxia; Xiao, Tiqiao; Chen, Min; Shao, Qun; York, Peter; Singh, Vikaramjeet; Yin, Xianzhen; Gu, Jingkai; Zhang, Jiwen


    The orifice drilled in the membrane as a channel for drug delivery is the key functional part of the osmotic pumps for a controlled drug release system. Reported conventional microscopic evaluations of these orifices have been limited to measurement of two-dimensional cross-section diameters. This study was aimed at establishing a novel method to measure quantitatively the three-dimensional architectures of orifices based on synchrotron radiation X-ray microcomputed tomography (SR-μCT). Quantitative analysis of architectures extracted from captopril osmotic pumps drilled by a range of operating parameters indicated that laser power correlated with the cross section area, volume, surface area and depth of the orifices, while scanning speed of laser beam showed inverse relationships with the above structure characters. The synchrotron radiation based Fourier transform infrared microspectroscopy mapping showed that there was no apparent chemical change in the surrounding area of the orifice compared with the normal membrane region. Thus SR-μCT was successfully applied to marketed felodipine osmotic pumps for architectural evaluation of the orifices. In conclusion, the first three-dimensional structural insight of orifices in osmotic pump tablets by SR-μCT and structural reconstruction for the architectures has provided deeper insight into improving the design of advanced osmotic pumps for controlled drug release.

  2. Continuous-wave and Q-switched performance of an Yb:YAG/YAG composite thin disk ceramic laser pumped with 970-nm laser diode

    Institute of Scientific and Technical Information of China (English)

    Hong Cai; Jun Zhou; Hongming Zhao; Yunfeng Qi; Qihong Lou; Jingxing Dong; Yunrong Wei


    Using front face-pumped compact active mirror laser (CAMIL) structure, we have demonstrated an Yb:YAG/YAG composite ceramic disk laser with pumping wavelength at 970 nm. The laser has been operated in both continuous-wave (CW) and Q-switching modes. Under CW operation, laser output power of 1.05 W with 2% transmission output coupler was achieved at the wavelength of 1031 nm. Qswitched laser output was gotten by using an acousto-optic Q-switch. The repetition rate ranged from 1 to 30 kHz and the pulse width varied from 166 to 700 ns.

  3. High Efficient LGp0 End Pumped Nd:YAG Laser

    CSIR Research Space (South Africa)

    Ngcobo, S


    Full Text Available The transformation of a single mode TEM00 Gaussian beam by forcing the laser to operate into a symmetrical single mode higher order TEMp0 Laguerre Gaussian beam intensity distribution is very useful in improving and substantially increasing...

  4. 8-mJ TEM(00) diode-end-pumped frequency-quadrupled Nd:YAG laser. (United States)

    Feugnet, G; Pocholle, J P


    A frequency-quadrupled Nd:YAG laser pumped by a commercially available high-brightness stack is described. A master oscillator power amplifier configuration was implanted, and the laser delivered energy of 8 mJ at 0.266microm . The laser was air cooled for easy use.

  5. High-power diode-end-pumped Tm:YLF slab laser delivering 189 W at 1890 nm

    CSIR Research Space (South Africa)

    Koen, W


    Full Text Available The authors present a high-power Tm:YLF slab laser double-end-pumped by two 300 W laser diode stacks. The resonator was designed such that the laser emitted at 1890 nm instead of the conventional operating wavelength of 1912 nm. At full incident...

  6. Measurement of thermal lensing in end-pumped Yb-doped yttrium vanadate crystal and sesquioxide laser ceramics (United States)

    Pestryakov, E. V.; Petrov, V. V.; Trunov, V. I.; Kirpichnikov, A. V.; Merzliakov, M. A.; Laptev, A. V.; Polyakov, K. V.


    The results of theoretical and experimental study of thermal lensing in diode-pumped Yb:YVO4 laser crystal, Yb:Y2O3 and Yb:Sc2O3 laser ceramics are presented. Shown, that influence of thermo-lensing effect is necessary to consider for creation of effective high-intensity femtosecond Yb-doped laser systems.

  7. Modelling two-phase transport of 3H/3He

    NARCIS (Netherlands)

    Visser, A.; Schaap, J.D.; Leijnse, T.; Broers, H.P.; Bierkens, M.F.P.


    Degassing of groundwater by excess denitrification of agricultural pollution complicates the interpretation of 3H/3He data and hinders the estimation of travel times in nitrate pollution studies. In this study we used a two-phase flow and transport model (STOMP) to evaluate the method presented by

  8. Modelling two-phase transport of 3H/3He

    NARCIS (Netherlands)

    Visser, A.; Schaap, J.D.; Leijnse, T.; Broers, H.P.; Bierkens, M.F.P.


    Degassing of groundwater by excess denitrification of agricultural pollution complicates the interpretation of 3H/3He data and hinders the estimation of travel times in nitrate pollution studies. In this study we used a two-phase flow and transport model (STOMP) to evaluate the method presented by V

  9. The {sup 3}He neutron-spin filter at ILL

    Energy Technology Data Exchange (ETDEWEB)

    Tasset, F.; Heil, W.; Humblot, H.; Lelievre-Berna, E.; Roberts, T. [Institut Max von Laue - Paul Langevin (ILL), 38 - Grenoble (France)


    Neutron-Spin Filters (NSF) using gaseous polarised {sup 3}He have long been recognised as of enormous potential value in many polarised neutron-scattering applications and, accordingly, ILL started a development programme some years ago. This report gives an account of the present status of the project. (author). 13 refs.

  10. Conceptual design of the D- sup 3 He reactor artemis

    Energy Technology Data Exchange (ETDEWEB)

    Momoto, H.; Tomita, Y. (National Inst. for Fusion Science, Nagoya (JP)); Ishida, A. (Niigata Univ. (Japan)); Miley, G.H. (Illinois Univ., Urbana, IL (United States)); Kohzaki, Y. (Inst. for Future Technology, Tokyo (JP)); Ohi, S. (Osaka Univ., Suita (Japan)); Ohnishi, M. (Kyoto Univ. (Japan)); Sato, H. (Himeji Inst. of Tech., Hyogo (Japan)); Steinhauer, L.C. (STI Optronics, Inc., Bellevue, WA (US)); Tuszewski, M. (Los Alamos National Lab., NM (United States))


    In this paper, a comprehensive design study of the D-{sup 3}He-fueled field-reversed configuration (FRC) reactor Artemis is carried out for the purpose of proving its attractive characteristics and clarifying the critical issues for a commercial fusion reactor. The FRC burning plasma is stabilized and sustained in a steady equilibrium by means of preferential trapping of D-{sup 3}He fusion-produced energetic protons. A novel direct energy converter for 15-MeV protons is also presented. On the basis of consistent fusion plasma production and simple engineering, a compact and simple reactor concept is presented. The D-{sup 3}He FRC power plant offers a most attractive prospect for energy development. It is environmentally acceptable in terms of radioactivity and fuel resources, and the estimated cost of electricity is low compared with a light water reactor. Critical physics and engineering issues in the development of the D-{sup 3}He FRC reactor are clarified.

  11. Dating degassed groundwater with 3H/3He

    NARCIS (Netherlands)

    Visser, A.; Broers, H.P.; Bierkens, M.F.P.


    The production of gases in groundwater under contaminated locations by geochemical and biological processes is not uncommon. Degassing of these gases from groundwater and repartitioning of noble gases between water and gas phase distorts groundwater dating by 3H/3He. We observed noble gas concentrat

  12. Dating degassed groundwater with 3H/3He

    NARCIS (Netherlands)

    Visser, A.; Broers, H.P.; Bierkens, M.F.P.


    The production of gases in groundwater under contaminated locations by geochemical and biological processes is not uncommon. Degassing of these gases from groundwater and repartitioning of noble gases between water and gas phase distorts groundwater dating by 3H/3He. We observed noble gas

  13. Hyperpolarised sup 3 He gas production for magnetic resonance imaging of the human air ways

    CERN Document Server

    Fichele, S


    This thesis describes the experimental techniques, and methods employed in hyperpolarised sup 3 He gas production and magnetic resonance imaging of the human air-ways, using spin-echo sequences and MR tagging techniques. An in-house polariser utilising the metastability optical pumping technique was constructed. The main results of this work are concerned with engineering difficulties involved in compressing HP sup 3 He and a large proportion of this PhD thesis details the design, construction, and performance of an in-house built peristaltic compressor. In preliminary imaging experiments using RARE, high signal to noise projection images of the lungs were acquired using less than 0.5 cm sup 3 (STP) of purely polarised HP gas. Later, increased HP gas quantities (typically 10 cm sup 3) were obtained by employing the peristaltic compressor. Consequently we could acquire 10 mm thick slices spanning the entire lung following a single sup 3 He gas bolus administration. Finally, the first results using MR tagging t...

  14. Kinetic model of stimulated emission created by resonance pumping of aluminum laser-induced plasma (United States)

    Gornushkin, I. B.; Kazakov, A. Ya.


    Stimulated emission observed experimentally in an aluminum laser induced plasma is modeled via a kinetic approach. The simulated emission at several cascade transitions is created by a pump laser guided through the plasma at several microseconds after its creation and tuned in resonance with the strong 3s23p-3s24s transition at 266 nm. A two-dimensional space-time collisional radiative plasma model explains the creation of the population inversion and lasing at wavelengths of 2100 n m and 396.1 nm. The population inversion for lasing at 2100 n m is created by depopulation of the ground 3s23p state and population of the 3s25s state via the absorption of the resonant radiation at 266 nm. The population inversion for lasing at 396.1 nm occurs during the laser pulse via the decay of the population of the pumped 3s25s state to the excited 3s24s state via cascade transitions driven optically and by collisions. In particular, efficient are the mixing transitions between neighboring states separated by small gaps on the order of k T at plasma temperatures of 5000-10 000 K. The model predicts that the population inversion and corresponding gain may reach high values even at very moderate pump energy of several μJ per pulse. The efficiency of lasing at 2100 n m and 396.1 nm is estimated to be ˜3% and 0.05%, correspondingly with respect to the pump laser intensity. The gain for lasing at 396.1 nm can reach as high as ˜40 cm-1. The polarization effect that the pump radiation at 266 nm imposes on the stimulated emission at 396.1 nm is discussed. The calculated results are favorably compared to experimental data.

  15. 3.1 kW monolithic MOPA configuration fibre laser bidirectionally pumped by non-wavelength-stabilized laser diodes (United States)

    Yan, Ping; Huang, Yusheng; Sun, Junyi; Li, Dan; Wang, Xuejiao; Gong, Mali; Xiao, Qirong


    We report an all-fibre monolithic master oscillator power amplifier configuration fibre laser bidirectionally pumped by non-wavelength-stabilized laser diodes. The Raman Effect and thermal problems can be effectively suppressed by the bidirectional pumping configuration. A small core diameter double-clad ytterbium-doped fibre is utilized in the amplifier for a refined beam quality control. As a result, a maximum output power of 3122 W and an optical-to-optical efficiency of 81.4% are achieved with near-diffraction-limitation beam quality. No mode instability was detected via a photodiode. Also, the output power instability was measured to be less than 0.6% during a continuous operation of 2 h.

  16. 300 W laser-diode dual-end-pumped Nd:YVO4 Innoslab laser (United States)

    Duan, Yabo; Song, Chengtian; Mao, Yefei


    We demonstrate a continuous wave neodymium-doped vanadate (Nd:YVO4) experiment with the laser diode dual end pumped directly in the band at 880 nm. Due to the advantage of the Innoslab laser, a 22 mm  ×  10 mm  ×  1 mm Nd:YVO4 crystal was used. By using a positive confocal unstable-stable hybrid fold resonator, a maximum power of 330 W was obtained at the absorbed pump power of 725 W. The corresponding optical-to-optical efficiency and slope efficiency were 45.5% and 55.8%, respectively. At an output power of 300 W, the beam quality factors M 2 in the unstable direction and stable direction were 1.7 and 2.1, respectively.

  17. Pump-probe differencing technique for cavity-enhanced, noise-canceling saturation laser spectroscopy

    CERN Document Server

    De Vine, G; Close, J D; Gray, M B; Vine, Glenn de; Clelland, David E. Mc; Close, John D.; Gray, Malcolm B.


    We present an experimental technique enabling mechanical-noise free, cavity-enhanced frequency measurements of an atomic transition and its hyperfine structure. We employ the 532nm frequency doubled output from a Nd:YAG laser and an iodine vapour cell. The cell is placed in a traveling-wave Fabry-Perot interferometer (FPI) with counter-propagating pump and probe beams. The FPI is locked using the Pound-Drever-Hall (PDH) technique. Mechanical noise is rejected by differencing pump and probe signals. In addition, this differenced error signal gives a sensitive measure of differential non-linearity within the FPI.

  18. Supercontinuum generation pumped by a regeneratively mode-locked fiber laser

    Institute of Scientific and Technical Information of China (English)

    JIA Dong-fang; TAN Bin; WANG Zhao-ying; GE Chun-feng; NI Wen-jun; LI Shi-chen


    Supercontinuum(SC) generation in a dispersion-shifted fiber(DSF) pumped by a 10 GHz regeneratively mode-locked fiber laser(RMLFL) is presented.Optimization of pump wavelength leads to a 20 dB bandwidth of 58.73 nm,which covers the whole C band and part of L band.Using an angle-tuning thin film filter,multi-wavelength and pico-second pulse trains of low chirp could be chosen from the SC spectrum.Amplified spontaneous emission(ASE) induced degeneration of the achieved pulse trains is observed and discussed.

  19. Pulsed pump: Thermal effects in solid state lasers under super-Gaussian pulses

    Indian Academy of Sciences (India)

    H Nadgaran; M Sabaian


    Solid state laser (SSL) powers can be realistically scaled when pumped by a real, efficient and multimode pulse. In this work, a fourth-order super-Gaussian pulse was assumed as a pump for SSL's and a complete analytical expression for the thermal phase shift is given. Moreover, the focal length of thermal lens in paraxial ray approximation regime was studied. The results when applied to a Ti : sapphire crystal show an appreciable correction for abberation compared to a top-hat pulse.

  20. Measurement of the plasma astrophysical S factor for the 3He(D, p)4He reaction in exploding molecular clusters

    CERN Document Server

    Barbui, M; Bonasera, A; Hagel, K; Schmidt, K; Natowitz, J B; Burch, R; Giuliani, G; Barbarino, M; Zheng, H; Dyer, G; Quevedo, H J; Gaul, E; Bernstein, A C; Donovan, M; Kimura, S; Mazzocco, M; Consoli, F; De Angelis, R; Andreoli, P; Ditmire, T


    The plasma astrophysical S factor for the 3He(D, p)4He fusion reaction was measured for the first time at temperatures of few keV, using the interaction of intense ultrafast laser pulses with molecular deuterium clusters mixed with 3He atoms. Different proportions of D2 and 3He or CD4 and 3He were mixed in the gas jet target in order to allow the measurement of the cross-section for the 3He(D, p)4He reaction. The yield of 14.7 MeV protons from the 3He(D, p)4He reaction was measured in order to extract the astrophysical S factor at low energies. Our result is in agreement with other S factor parameterizations found in the literature.

  1. Stable, continuous-wave, intracavity, optical parametric oscillator pumped by a semiconductor disk laser (VECSEL). (United States)

    Stothard, D J M; Hopkins, J-M; Burns, D; Dunn, M H


    We report relaxation oscillation free, true continuous-wave operation of a singly-resonant, intracavity optical parametric oscillator (OPO) based upon periodically-poled, MgO-doped LiNbO3 and pumped internal to the cavity of a compact, optically-excited semiconductor disk laser (or VECSEL). The very short upper-laser-state lifetime of this laser gain medium, coupled with the enhancing effect of the high-finesse pump laser cavity in which the OPO is located, enables a low threshold, high efficiency intracavity device to be operated free of relaxation oscillations in continuous-wave mode. By optimizing for low-power operation, parametric threshold was achieved at a diode-laser power of only 1.4 W. At 8.5 W of diode-laser power, 205 mW of idler power was extracted, indicating a total down-converted power of 1.25 W, and hence a down-conversion efficiency of 83%.

  2. Reviews of a Diode-Pumped Alkali Laser (DPAL): a potential high powered light source (United States)

    Cai, He; Wang, You; Han, Juhong; An, Guofei; Zhang, Wei; Xue, Liangping; Wang, Hongyuan; Zhou, Jie; Gao, Ming; Jiang, Zhigang


    Diode pumped alkali vapor lasers (DPALs) were first developed by in W. F. Krupke at the beginning of the 21th century. In the recent years, DPALs have been rapidly developed because of their high Stokes efficiency, good beam quality, compact size and near-infrared emission wavelengths. The Stokes efficiency of a DPAL can achieve a miraculous level as high as 95.3% for cesium (Cs), 98.1% for rubidium (Rb), and 99.6% for potassium (K), respectively. The thermal effect of a DPAL is theoretically smaller than that of a normal diode-pumped solid-state laser (DPSSL). Additionally, generated heat of a DPAL can be removed by circulating the gases inside a sealed system. Therefore, the thermal management would be relatively simple for realization of a high-powered DPAL. In the meantime, DPALs combine the advantages of both DPSSLs and normal gas lasers but evade the disadvantages of them. Generally, the collisionally broadened cross sections of both the D1 and the D2 lines for a DPAL are much larger than those for the most conventional solid-state, fiber and gas lasers. Thus, DPALs provide an outstanding potentiality for realization of high-powered laser systems. It has been shown that a DPAL is now becoming one of the most promising candidates for simultaneously achieving good beam quality and high output power. With a lot of marvelous merits, a DPAL becomes one of the most hopeful high-powered laser sources of next generation.

  3. Power Beaming to Space Using a Nuclear Reactor-Pumped Laser (United States)

    Lipinski, Ronald J.; Monroe, David K.; Pickard, Paul S.


    The present political and environmental climate may slow the inevitable direct utilization of nuclear power in space. In the meantime, there is another approach for using nuclear energy for space power. That approach is to let nuclear energy generate a laser beam in a ground-based nuclear reactor-pumped laser (RPL), and then beam the optical energy into space. Potential space applications for a ground-based RPL include (1) illuminating geosynchronous communication satellites in the earth's shadow to extend their lives, (2) beaming power to orbital transfer vehicles, (3) providing power (from earth) to a lunar base during the long lunar night, and (4) removing space debris. FALCON is a high-power, steady-state, nuclear reactor-pumped laser (RPL) concept which is being developed by the Department of Energy with Sandia National Laboratories as the lead laboratory. The FALCON program has experimentally demonstrated reactor-pumped lasing in various mixtures of xenon, argon, neon, and helium at wavelengths of 585, 703, 725, 1271, 1733, 1792, 2032, 2630, 2650, and 3370 nm with intrinsic efficiency as high as 2.5%. Frequency-doubling the 1733-nm line would yield a good match for photovoltaic arrays at 867 nm. Preliminary designs of an RPL suitable for power beaming have been completed. The MW- class laser is fairly simple in construction, self-powered, closed-cycle (no exhaust gases), and modular. This paper describes the FALCON program accomplishments and power-beaming applications.

  4. Selective removal of dental composite with a diode-pumped Er:YAG laser (United States)

    Fried, William A.; Chan, Kenneth H.; Darling, Cynthia L.; Fried, Daniel


    Selective removal of dental composite with high precision is best accomplished using lasers operating at high pulse repetition rates focused to a small spot size. Conventional flash-lamp pumped Er:YAG lasers are poorly suited for this purpose, but new diode-pumped Er:YAG lasers have become available operating at high pulse repetition rates. The purpose of this study was to compare the ablation rates and selectivity of enamel and composite for a 30 W diode-pumped Er:YAG laser operating with a pulse duration of 30-50-μs and evaluate it's suitability for the selective removal of composite from tooth surfaces. The depth of ablation and changes in surface morphology were assessed using digital microscopy. The fluence range of 30-50 J/cm2 appeared optimal for the removal of composite, and damage to sound enamel was limited to less than 100-μm after the removal of composite as thick as 700-800-μm. Future studies will focus on the use of methods of feedback to further increase selectivity.

  5. Gigahertz frequency comb from a diode-pumped solid-state laser. (United States)

    Klenner, Alexander; Schilt, Stéphane; Südmeyer, Thomas; Keller, Ursula


    We present the first stabilization of the frequency comb offset from a diode-pumped gigahertz solid-state laser oscillator. No additional external amplification and/or compression of the output pulses is required. The laser is reliably modelocked using a SESAM and is based on a diode-pumped Yb:CALGO gain crystal. It generates 1.7-W average output power and pulse durations as short as 64 fs at a pulse repetition rate of 1 GHz. We generate an octave-spanning supercontinuum in a highly nonlinear fiber and use the standard f-to-2f carrier-envelope offset (CEO) frequency fCEO detection method. As a pump source, we use a reliable and cost-efficient commercial diode laser. Its multi-spatial-mode beam profile leads to a relatively broad frequency comb offset beat signal, which nevertheless can be phase-locked by feedback to its current. Using improved electronics, we reached a feedback-loop-bandwidth of up to 300 kHz. A combination of digital and analog electronics is used to achieve a tight phase-lock of fCEO to an external microwave reference with a low in-loop residual integrated phase-noise of 744 mrad in an integration bandwidth of [1 Hz, 5 MHz]. An analysis of the laser noise and response functions is presented which gives detailed insights into the CEO stabilization of this frequency comb.

  6. An end pumped all internal reflection small-sized slab picosecond laser amplifier (United States)

    Chen, Junchi; Peng, Yujie; Su, Hongpeng; Leng, Yuxin


    An end pumped all internal reflection small-sized slab picosecond laser system amplifier is proposed and demonstrated based on the common Nd:YAG crystal. A cylinder lens is introduced to pre-compensate for the one-dimensional thermal effect caused by the high power pumping laser. The maximum output powers of 6.6 and 6.3 W are obtained at the absorbed pumping power of 25 W without and with a cylinder mirror, and the corresponding optical conversion efficiencies are about 10.4% and 9.3% respectively. The measured M 2 factors along the slow and fast axes are 1.71 and 2.47 respectively. The instability of the maximum output laser is below 0.8% (RMS) within measuring time up to 15 min. It is demonstrated that the all internal reflection slab can support long enough optical gain distance to realize the signal laser amplification for the newly developed crystal even with small size and low doped concentration.

  7. Spontaneous Generation of Vortex Array Beams from a Thin-Slice Solid-State Laser with Wide-Aperture Laser-Diode Pumping

    CERN Document Server

    Otsuka, Kenju


    We studied complex lasing pattern formations in a thin-slice solid-state laser with wide-aperture laser-diode end-pumping. Radial and rectangular vortex arrays were found to be formed in a controlled fashion with symmetric and asymmetric pump beam profiles, respectively. Most of these vortices exhibited single-frequency oscillations arising from a spontaneous process of transverse mode locking of nearly degenerate modes assisted by the laser nonlinearity. Single-frequency rectangular array beams consisting of a large number of vortices, e.g., closely packed 36 or 46 vortex pixels, were generated, originating from Ince-Gaussian modes excited by the asymmetric pumping.

  8. Pumping laser excited spins through MgO barriers (United States)

    Martens, Ulrike; Walowski, Jakob; Schumann, Thomas; Mansurova, Maria; Boehnke, Alexander; Huebner, Torsten; Reiss, Günter; Thomas, Andy; Münzenberg, Markus


    We present a study of the tunnel magneto-Seebeck (TMS)4 effect in MgO based magnetic tunnel junctions (MTJs). The electrodes consist of CoFeB with in-plane magnetic anisotropy. The temperature gradients which generate a voltage across the MTJs layer stack are created using laser heating. Using this method, the temperature can be controlled on the micrometer length scale: here, we investigate, how both, the TMS voltage and the TMS effect, depend on the size, position and intensity of the applied laser spot. For this study, a large variety of different temperature distributions was created across the junction. We recorded 2D maps of voltages generated by heating in dependence of the laser spot position and the corresponding calculated TMS values. The voltages change in value and sign, from large positive values when heating the MTJ directly in the centre to small values when heating the junction on the edges and even small negative values when heating the sample away from the junction. Those zero crossings lead to very high calculated TMS ratios. Our systematic analysis shows, that the distribution of the temperature gradient is essential, to achieve high voltage signals and reasonable resulting TMS ratios. Furthermore, artefacts on the edges produce misleading results, but also open up further possibilities of more complex heating scenarios for spincaloritronics in spintronic devices.

  9. GaAs-based high temperature electrically pumped polariton laser

    Energy Technology Data Exchange (ETDEWEB)

    Baten, Md Zunaid; Bhattacharya, Pallab, E-mail:; Frost, Thomas; Deshpande, Saniya; Das, Ayan [Center for Photonic and Multiscale Nanomaterials, Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, Michigan 48109 (United States); Lubyshev, Dimitri; Fastenau, Joel M.; Liu, Amy W. K. [IQE, Inc., 119 Technology Drive, Bethlehem, Pennsylvania 18015 (United States)


    Strong coupling effects and polariton lasing are observed at 155 K with an edge-emitting GaAs-based microcavity diode with a single Al{sub 0.31}Ga{sub 0.69}As/Al{sub 0.41}Ga{sub 0.59}As quantum well as the emitter. The threshold for polariton lasing is observed at 90 A/cm{sup 2}, accompanied by a reduction of the emission linewidth to 0.85 meV and a blueshift of the emission wavelength by 0.89 meV. Polariton lasing is confirmed by the observation of a polariton population redistribution in momentum space and spatial coherence. Conventional photon lasing is recorded in the same device at higher pump powers.

  10. Electrically pumped photonic crystal laser constructed with organic semiconductors (United States)

    Cai, Yuan-yuan; Chen, Xiao; Li, Ning; Li, Chang-wei; Wang, Yi-quan


    We experimentally demonstrate the lasing action of electrically pumped octagonal quasi-crystal microcavities formed in a layer of conjugated polymer poly[2-methoxy- 5-(2-ethylhexyloxy)-1,4-phenylenevinylene] (MEH-PPV) sandwiched between two electrodes. Lasing from a point-defect microcavity is observed at a wavelength of 606 nm with a narrow linewidth of 0.5 nm, limited by the spectrometer resolution. Due to the properties of the photonic bandgap and localization in photonic crystals, the threshold current for lasing is low at 0.8 mA. The ion injection in the luminescent polymer layer by focused ion beam (FIB) etching technology also contributes to enhancement of the carrier density as well as the mobility, resulting in an increase of MEH-PPV conductivity and a decrease of turn-on voltage.

  11. A 3He gas heat switch for the 0.5-2 K temperature range (United States)

    Smith, Eric N.; Parpia, Jeevak M.; Beamish, John R.


    We have constructed a prototype heat switch for use in a cyclic demagnetization apparatus. The desired operating range of the switch is from 0.5 to 1.8 K. The measured conductivity of the switch is 50 μW/ K at 1.5 K when ‘off ’ and 8 mW/K at 0.5 K when ‘on’. The switching is carried out by 3He gas which is admitted and extracted from the device by a miniature charcoal adsorption pump which is controlled by electrical heat and a weak thermal link to a pumped 4He bath. In this paper we discuss details of construction and the performance as a function of temperature, and consider the switching time between on and off states.

  12. Development of high-brightness high-power fiber laser pump sources (United States)

    Priest, J. A.; Faircloth, Brian O.; Swint, Reuel B.; Coleman, James J.; Forbes, David V.; Zediker, Mark S.


    High power fiber lasers have strong potential for use in both commercial and military applications. Improved wall plug efficiency over Nd:YAG and CO2 lasers combined with up to a 10-fold improvement in beam quality, make fiber lasers extremely attractive for industrial applications such as welding and cutting. In military applications, fiber lasers offer a simplified logistic train, a deep magazine limited only by electric power, and a compact footprint, allowing theater defense and self-protection of combat platforms with speed of light engagement and flexible response. Commercial viability of these systems, however, is limited by the availability of compact, cost effective, and reliable diode laser pump sources in the multi-kilowatt regime. The relatively low brightness of diode laser sources has complicated the task of building high power pumps at a reasonable cost. In response to this need, Nuvonyx, Inc. in conjunction with the University of Illinois at Urbana-Champaign, has been developing a new technology for producing high power, single lateral mode devices which do not suffer form the instabilities mentioned above. The waveguide consists of a narrow section, approximately 2 μm wide, which flares to approximately 12 μm wide at the output facet. The flaring of the waveguide increases the gain volume and reduces the optical power density at the facet allowing for higher output power capability. The index guide is defined using an epitaxial process which allows the confinement of the mode to be reduced as the width of the guide expands. Thus, the mode is confined in a single mode waveguide throughout the cavity maintaining stability of the mode to the emitting facet. In November 2002, Nuvonyx, Inc. was awarded a contract with the Air Force Research Lab, Kirtland AFB, Albuquerque, NM, to transition these devices to production quality for use in high-power fiber laser pumps. Partnered with Alfalight, Inc. and the University of Illinois, we have begun initial

  13. Compact, diode-pumped, solid-state lasers for next generation defence and security sensors (United States)

    Silver, M.; Lee, S. T.; Borthwick, A.; McRae, I.; Jackson, D.; Alexander, W.


    Low-cost semiconductor laser diode pump sources have made a dramatic impact in sectors such as advanced manufacturing. They are now disrupting other sectors, such as defence and security (D&S), where Thales UK is a manufacturer of sensor systems for application on land, sea, air and man portable. In this talk, we will first give an overview of the market trends and challenges in the D&S sector. Then we will illustrate how low cost pump diodes are enabling new directions in D&S sensors, by describing two diode pumped, solid- state laser products currently under development at Thales UK. The first is a new generation of Laser Target Designators (LTD) that are used to identify targets for the secure guiding of munitions. Current systems are bulky, expensive and require large battery packs to operate. The advent of low cost diode technology, merged with our novel solid-state laser design, has created a designator that will be the smallest, lowest cost, STANAG compatible laser designator on the market. The LTD delivers greater that 50mJ per pulse up to 20Hz, and has compact dimensions of 125×70×55mm. Secondly, we describe an ultra-compact, eye-safe, solid-state laser rangefinder (LRF) with reduced size, weight and power consumption compared to existing products. The LRF measures 100×55×34mm, weighs 200g, and can range to greater than 10km with a single laser shot and at a reprate of 1Hz. This also leverages off advances in laser pump diodes, but also utilises low cost, high reliability, packaging technology commonly found in the telecoms sector. As is common in the D&S sector, the products are designed to work in extreme environments, such as wide temperature range (-40 to +71°C) and high levels of shock and vibration. These disruptive products enable next- generation laser sensors such as rangefinders, target designators and active illuminated imagers.


    Directory of Open Access Journals (Sweden)

    A. V. Belikov


    Full Text Available Subject of Study. The paper discusses the breadboarding results of compact diode pumped laser. The laser is based on Yb,Er:glass slab active element and frustrated total internal reflection (FTIR shutter and features of the impact of generated pulses at the water-containing media. The transmitter working in cavity dumping mode provides generation of single microsecond pulses or regular trains of these pulses with peak power up to 100 kW and average output power up to 8 W. The laser allows varying output parameters of radiation in wide range and is designed for the usage in technology and biomedical applications. The possibilities of the laser radiation parameters adapting for application in a compact laser cataract extraction complex are examined. Method. The energy efficient for three level active medium method of lasing pulses repetition rate increasing was investigated, which comprises the generation of pulse trains by several FTIR shutter switching on one pump pulse. We carried out analysis of application possibility for microsecond laser pulses with peak power of tens of kilowatts at wavelength of 1,54 μm in the processing of water-containing tissues. The acoustic response on the interaction of radiation with a model environment was studied. Main Results. In the modulation mode of useful (active losses lasing pulses have been obtained with microsecond duration and energy more than 100 mJ and trains of pulses with total energy of 0,5 J at the effective pulse repetition rate of more than 50 Hz. The minimal permissible period of laser pulses in train (300 μs has been established experimentally on the basis of optoacoustic studies. It meets the criteria of operation noninvasiveness consisting in prevention of the risk of posterior lens capsule damage with laser radiation. Practical Relevance. The results obtained with the layout of diode pumped Yb,Er:glass laser with cavity dumping and slab active element are presently record for diode-pumped

  15. Numerical simulation of end-pumped CW Nd3+: GdVO4 laser at 1063 nm

    Institute of Scientific and Technical Information of China (English)

    Zu Ning-Ning; Sun Gui-Juan; Dai Zhen-Wen


    A theoretical model to simulate an end-pumped CW Nda+:GdVO4 laser at 1063nm is presented.Its essence is to use the propagation equations to demonstrate the spatial evolutions of the pump and the laser powers in the cavity,hence it is applicable to both low and high gain lasers.The simulation results obtained by this model are in good agreement with the experimental observations reported in the literature for a Ti:sapphire-pumped Nd3+:GdVO4 laser.Moreover,some parameters,such as the reflectivity of output coupler,the spot size of laser beam and the crystal length,are discussed with a view to optimizing the laser performance.

  16. Linearly polarized pumped passively Q-switched Nd:YVO4 microchip laser for Ince-Gaussian laser modes with controllable orientations (United States)

    He, Hong-Sen; Zhang, Ming-Ming; Dong, Jun; Ueda, Ken-Ichi


    A tilted, linearly polarized laser diode end-pumped Cr4+:YAG passively Q-switched a-cut Nd:YVO4 microchip laser for generating numerous Ince-Gaussian (IG) laser modes with controllable orientations has been demonstrated by selecting the crystalline orientation of an a-cut Nd:YVO4 crystal. The same IG laser mode with different orientations has been achieved with the same absorbed pump power in a passively Q-switched Nd:YVO4 microchip laser under linearly polarized pumping when the incident pump power and the crystalline orientation of an a-cut Nd:YVO4 crystal are both properly selected. The significant improvement of pulsed laser performance of controllable IG modes has been achieved by selecting the crystalline orientation of an a-cut Nd:YVO4 crystal. The maximum pulse energy is obtained along the a-axis of an a-cut Nd:YVO4 crystal and the highest peak power is achieved along the c-axis of an a-cut Nd:YVO4 crystal, respectively, which has potential applications on quantum computation and optical manipulation. The generation of controllable IG laser modes in microchip lasers under linearly polarized pumping provides a convenient and universal way to control IG laser mode numbers with anisotropic crystal as a gain medium.

  17. Erbium Doped GaN Lasers by Optical Pumping (United States)


    control number. PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. Texas Technical University Box 41035 349 Admin Bldg Lubbock, TX 79409 -1035...obtained via growth by hydride vapor phase epitaxy (HVPE) in conjunction with a laser-lift-off (LLO) process . An Er doping level of 1.4 × 10^20 atoms/cm3...GPA to 4.0 (4.0 max scale): Number of graduating undergraduates funded by a DoD funded Center of Excellence grant for Education , Research and

  18. Big solar furnace as pumping source for high power lasers (United States)

    Payziyev, Sh.; Bakhramov, S.; Klichev, Sh.; Kasimov, A.; Riskiev, T.; Abdurakhmanov, A.; Fazilov, A.


    For effective conversion of the energy of the concentrated solar flux of 1 MW Big Solar Furnace of the Scientific and Production Association "Physics-Sun" (Tashkent) with focal spot size of about 40 cm into the coherent laser radiation, the several designs of the multi-element secondary concentrators for various active mediums with different thermal and optical characteristics were considered. For calculations of parameters of secondary concentrators the Ray tracing and Monte-Carlo methods were used and the numerical experiments were performed.

  19. XeF pump laser. Final technical report

    Energy Technology Data Exchange (ETDEWEB)


    The goal of this program was to demonstrate operation of an XeF laser of adequate energy, efficiency and beam quality at high repetition rates. The specific design goals were: PRF greater than or equal to 10 kHz, energy output greater than or equal to 50 mJ/pulse, efficiency greater than or equal to 0.3%, and beam divergence angle less than or equal to 20x diffraction limited. In the following sections of this report we will discuss how these goals have been met.

  20. Dynamical Properties of a Single-Mode Laser Driven by Quadratic Pump Noise

    Institute of Scientific and Technical Information of China (English)

    ZHANG Li; CAO Li


    We propose a single-mode laser model driven by quadratic pump noise with cross correlation between the real and imaginary parts of the pump noise. The effect of the cross-correlation coefficient λp between the real and imaginary parts of the pump noise on dynamical properties is studied by using of the linear approximation. The theoretical expressions of intensity correlation function λ(t), normalized intensity fluctuation λ(0) are calculated.It is found that the most conspicuous effects of λp on both the intensity correlation function and the normalized intensity fluctuation appear at |λp| = √0.5, but not at |λp| = 1.