A strictly-all-fiberized 2 to 5 μm supercontinuum (SC) laser source with high conversion efficiency is demonstrated. A broadband thulium-doped fiber amplifier with spectral coverage of 2-2.7 μm is used to pump a piece of single-mode fluoroindate (InF3) fiber. A fusion spliced joint with loss down to 0.07 dB is achieved between a piece of silica fiber and the InF3 fiber, which keeps all-fiber structure and efficient pump power coupling. A 1.35-W SC with spectral coverage of 1.5-5.2 μm is obtained with a record power conversion efficiency of 59.5%. This research, to the best of the authors' knowledge, demonstrates the first all-fiber-integrated of InF3-fiber-based MIR-SC laser sources to date.
Self-organized passive coherent beam combination of multichannel pulsed laser with all-fiber configuration is reported.
The phase of multichannel Yb-doped pulsed fiber amplifiers is locked by optical feed-back ring cavity. The traditional
disadvantage of energy dissipation to side lode for lower aperture filling is solved via all-fiber laser array with
single-aperture configuration. Coherent beam combination of four pulsed fiber amplifiers is experimentally demonstrated.
Variable pulsed laser can be obtained by adjusting a AOM,stable combination pulsed fiber laser with excellent temporal
and spatial characteristic is achieved. The efficiency of coherent combination is up to 85.0%. This approach presented
here provides a feasible technique for power scaling of high-power pulsed fiber laser and maintaining beam quality
simultaneously.
An all-fiber pulsed Yb-doped laser is introduced. Different characteristic pulse laser can be obtained by adjusting output power and signal generator with tunable 15ns~1μs pulse duration, tunable 50Hz~5MHz repetition rate. Average power1.24W was obtained at 10kHz, the FWHM was 65 ns, the single-pulse power 0.13mJ and peak-power 2kW. At 100Hz the peak-power can reach 10kW with output power 84mW,pulse FWHM 86ns. The all-fiber laser have simple configuration, fully fiberized cavities without the need for careful alignment of free-space components allowing for robust and compact system designs. it’s parameter can be easily adjusted by AOM. A wide range of independently-tunable pulse durations and repetition rates are desirable for deployment in industrial applications,including high-power nonlinear wavelength conversion processes, LIDAR, etc. also greatly extend the applications in power amplified, pulse-compressed and high-repeat frequency as laser seeds.
Multiwavelength seed laser can suppress stimulated Brillouin scattering (SBS) and improve the ultimate output power of
the fiber laser amplifier. Coherent combining of multiwavelength lasers/amplifiers is a promising way to get much
higher total output power than coherent combining of the single frequency lasers/amplifiers. Coherent beam combining
of stimulated Brillouin scattering based multiwavelength fiber lasers is proposed and demonstrated. Multiwavelength
laser is generated using stimulated Brillouin scattering effect by seeded a 10 kilometer single mode fiber laser with a
single frequency laser and phase locking is achieved using stochastic parallel gradient descent (SPGD) algorithm.
Experiment results shows that more than 15 wavelengths are generated for the laser. With active phase control, mean
power of the main-lobe in close-loop is 1.37 times of that value in open-loop and the visibility of the long exposure
interference pattern is 0.37. Scale up this architecture to higher power involves introduction of power amplifiers,
increasing channel number of amplifiers and power of each individual amplifier.
The free-vortex aerodynamic windows (abbr. FADW) can take the place of the conventional solid windows for high energy lasers to solve the problems caused by the intrinsic fractional absorption of the laser energy. Usually the procedure in designing FADW includes two central processes. The first is to design the asymmetric supersonic laval nozzle using the method of characteristics and the method of simple wave under the ideal conditions, and the second is to design the diffuser. The method of designing the diffuser of FADW is based on the experimental method mostly, but the diffuser's properties influences the performance ofthe overall FADW system deadly, so an experimental prototype of FADW whose structure and layout is adjustable has been designed and manufactured to optimize the design of the diffuser for FADW system. This paper reports the design methods of the FADW system and discusses the experimental results. The results show that this prototype of the FADW has good running properties, and FADW whose structure and layout is adjustable can be used to optimize the FADW design perfectly.
KEYWORDS: Aerodynamics, Interferometry, Optical testing, High power lasers, Crystals, Laser crystals, Laser optics, Laser resonators, Fluctuations and noise, Laser energy
The concept of the free-vortex aerodynamic windows (FADW) is one of the best effective methods taking the place of the conventional beam output crystal windows of high power laser. An experimental model of the supersonic free-vortex aerodynamic window has been designed and made in our latest study. This paper studies the aero-optical phenomena of the FADWs supersonic jet to realize the laser optical quality degradation caused by the free- vortex jet, and to find out the relation of output laser beam quality through the FADW to the structure of the FADWs shearing interferometry. At last the structure of FADWs jet has been studied by means of shearography.
Different geometry nozzles used in CW hydrogen fluoride chemical laser are investigated. Four geometry parameters, including throat width; area ratio; axis length and base width are considered. The flow properties, laser outcoupling power and small signal gain (SSG) of a Fabry-Perot resonator are calculated. The results show that when throat width and area ratio increase, the power and SSG peak will decrease in varying degree; they also varied when axis length changed; larger base width is related to lower cavity pressure, and smaller base width is related higher cavity pressure.
The He is usually used as diluent in combustion cw hydrogen/deuterium fluoride (HF/DF) chemical lasers. Sometimes, the N2 is also used as diluent in cw HF/DF chemical laser, because N2 is more cheaper than the He. It was thought that the efficiency of cw HF/DF laser with N2 diluent was lower than that of HF/DF laser with He diluent since the molecular weight of N2 is heavier than that of He. In this paper, the performance of cw DF chemical lasers with He and N2 diluent was investigated. The small signal gain, power spectral distributions, cavity pressure, power and efficiency of DF lasers with these two diluents have been calculated using a finite-difference technique for the numerical integration of the steady and unsteady Navier-Stokes equation with reactive flow (compressibility scaling method-CSM), which was developed in the chemical gas dynamic laboratory of the state institute of applied chemistry in Russia. The numerical results show that the efficiency of DF lasers with N2 diluent is not lower than that of the lasers with He diluent.
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