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Wang G.,Science and Technology on Solid State Laser Laboratory | Tang X.,Science and Technology on Solid State Laser Laboratory | Ren J.,Suzhou University | Huang Q.,Suzhou University | Wang W.,Science and Technology on Solid State Laser Laboratory
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2016

The wavefront can keep stable while the laser system is adjusted well. Based on this characteristic, in order to improve the beam quality, we suggest to make mirror of free-form surface to compensate for the laser wavefront aberration. First, the theory of aberration compensated with free-form shape mirror is introduced, then through computer simulation, the mirror's capability of is discussed, lastly, the mirror is used by laser system which the average output power is 12.5KW. By the using of free-form shape mirror, laser's wavefront, beam quality of farfield and intensity of nearfield are improved obviously: the intensity of nearfield F is improved from 0.15 to 0.39; the wavefront's PV is improved from 6.3μm to 1.7μm; the wavefront's rms is improved from 2.0μm to 0.4μm; the beam quality of farfield β is improved from 5.25 to 1.8. Compared with deformable mirror of adaptive optics, the free-form shape mirror has its own advantage: low cost; with no increase to laser system complication; the free-from shape mirror can be used to compensated for high order wavefront aberration effectively. © 2016 SPIE.


Ren J.,Soochow University of China | Tang X.,Science and Technology on Solid State Laser Laboratory | Wang G.,Science and Technology on Solid State Laser Laboratory | Huang Q.,Soochow University of China | And 2 more authors.
Springer Proceedings in Physics | Year: 2017

Freeform optical components (FOCs) can effectively simplify optical system configuration and improve optical preforms, they can be applied on imaging system, illumination system and phase compensation system. Scattered sagittal points reported by coordinate measuring machine (CMM) often exist uncertainty and makes contour error inaccurate. A new model which subtracts CMM date from enveloping surface calculated by theoretical equation includes tilt, rotation and shift. Experiments result shows this method introduced by this article could efficiently analysis scattered CMM data and PV (Peak-to-valley) less than 2 μm which matched accuracy of CMM (1.8+ L/300 μm) and accuracy of fabrication error of SPDT. © Springer International Publishing AG 2017.


Li P.-X.,Beijing University of Technology | Liu Z.,Beijing University of Technology | Chi J.-J.,Beijing University of Technology | Yang C.,Beijing University of Technology | And 6 more authors.
Laser Physics Letters | Year: 2013

We report a picosecond ytterbium-doped double-clad fiber amplifier with a semiconductor saturable absorber mirror (SESAM) mode locking large mode area photonic crystal fiber (PCF) oscillator as the seed source. In the seed source, without any dispersion compensator or tunable elements in the cavity, we obtain self-starting mode locking of a tunable ytterbium-doped fiber oscillator. The 1037-1054 nm tuning range is achieved by proper adjustment of the half-wave plate and SESAM in the laser cavity. More than 1 W output power at the different wavelengths of operation has been achieved in experiments. For the fiber amplifier seeded with an SESAM mode locking PCF fiber oscillator, an average output power of 21 W has been demonstrated at a repetition rate of 45.9 MHz with a pulse duration of 8.8 ps, corresponding to a pulse energy of 458 nJ and a peak power of 52 kW. The nonlinear effect of self-phase-modulation (SPM), which results in spectral broadening, has been observed during the amplified experiments. © 2013 Astro Ltd.


Chi J.-J.,Beijing University of Technology | Li P.-X.,Beijing University of Technology | Yang C.,Beijing University of Technology | Zhao Z.-Q.,Beijing University of Technology | And 5 more authors.
Chinese Physics B | Year: 2013

We report on a theoretical and experimental study of an all-normal-dispersion (ANDi) Yb-doped mode-locked fiber laser, in which nonlinear polarization rotation (NPR) is used to realize mode-locking without any dispersion compensation. Based on the coupled nonlinear Schrödinger (CNLS) equation, a model simulating the mode-locked process of an all-normal-dispersion ring fiber laser is developed, which shows that the achievement of stable mode-locking depends on the alignment of the polarization controller (PC) along the fast-polarization axis of the fiber, the birefringence intensity, and the net cavity dispersion. According to the theoretical analysis, stable mode-locked pulses with pulse duration 300 ps and average output power 33.9 mW at repetition rate 36 MHz are obtained. © 2013 Chinese Physical Society and IOP Publishing Ltd.


Mao X.,Science and Technology on Solid State Laser Laboratory | Bi G.,Science and Technology on Solid State Laser Laboratory | Deng M.,Science and Technology on Solid State Laser Laboratory | Wang X.,Science and Technology on Solid State Laser Laboratory | Zhong G.,Science and Technology on Solid State Laser Laboratory
Zhongguo Jiguang/Chinese Journal of Lasers | Year: 2010

Laser diode (LD) end-pumped, thermally bonded Nd:YAG/Cr4+:YAG passively Q-switched laser is theoretically analysed and experimentally studied. The key laser parameters such as repetition rates, pulse width, peak power, pulse energy and mutual relation are investigated. The high peak power of 6.25 kW, pulse energy of 50 μJ, pulse width of 8 ns, repetition rate of 200 kHz laser are obtained. Experiment shows that thermally bonded solid state laser has high repetition rate, short pulse widh and high peak power.


Wang G.,Science and Technology on Solid State Laser Laboratory
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2014

Stochastic Parallel Gradient Descent(SPGD) algorithm can optimize the system exhibition firsthand without using of wavefront sensor, it predigests the adaptive optic system. Based on SPGD algotithm, a model with 32 element demormable mirror was simulated, the capability of correct toward static aberration and convergence of SPGD algorithm are analysed, the relationship of gain coefficient, stochastic perturbation amplitude are discussed, an adaptive adjustment of gain coefficient is proposed, and it can improve convergence rate effectively. © 2014 SPIE.


Zhang K.,Science and Technology on Solid State Laser Laboratory | Zhang D.Y.,Science and Technology on Solid State Laser Laboratory | Li Y.,Science and Technology on Solid State Laser Laboratory | Zhu C.,Science and Technology on Solid State Laser Laboratory | And 4 more authors.
Laser Physics | Year: 2013

We report a double stage linearly polarized ytterbium-doped double clad fiber (YDCF) amplifier working at 1063.9 nm, which generates a diffraction-limited output with an average power of 102 W at a repetition rate of 100 kHz, a pulse duration of 14.9 ns, a peak power of 68 kW, a 3 dB spectral width of about 0.47 nm and a polarization extinction ratio (PER) of about 13 dB. The seed is modulated to work at a suitable Gaussian shape to restrain the pulse distortion in the fiber amplifier. To the best of our knowledge, this result represents the highest peak power with narrow line-width and excellent beam quality in linearly polarized YDCF. © 2013 Astro Ltd.


Hao J.,Science and Technology on Solid State Laser Laboratory | Zhao H.,Science and Technology on Solid State Laser Laboratory | Zhang D.,Science and Technology on Solid State Laser Laboratory | Zhang L.,Science and Technology on Solid State Laser Laboratory | Zhang K.,Science and Technology on Solid State Laser Laboratory
Applied Optics | Year: 2015

This paper demonstrates an all-fiber narrow linewidth amplifier with a seed based on narrow linewidth fiber Bragg gratings (FBGs). The fiber amplifier achieves a narrow bandwidth output of 823 W, with an opto-optic efficiency of 84.5%. The pair of FBGs in the seed configuration helps to assure a narrow linewidth of the laser as 0.08 nm. In the laser profile, we introduce a cladding stripper with a sectional structure, which realizes high pump power leakage with high efficiency. The paper also discusses the impact of seed linewidth and fiber length on the SBS threshold in a narrow bandwidth laser. Based on this analysis, we discovered ways to inhibit SBS onset and scale power output. © 2015 Optical Society of America.


Sui X.-L.,Science and Technology on Solid state Laser Laboratory | Zhou S.-H.,Science and Technology on Solid state Laser Laboratory
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2013

The design and performance of Optical frequency modulation continuous wave (OFMCW) coherent laser radar is presented. By employing a combination of optical heterodyne and linear frequency modulation techniques and utilizing fiber optic technologies, highly efficient, compact and reliable laser radar suitable for operation in a space environment is being developed.We also give a hardware structure of the OFMCW coherent laser radar. We made a detailed analysis of the measurement error. Its accuracy in the speed range is less than 0.5%.Measurement results for the movement of the carrier has also made a detailed assessment. The results show that its acceleration vector has better adaptability. The circuit structure is also given a detailed design. At the end of the article, we give the actual authentication method and experimental results. © 2013 SPIE.


Lian T.,Xidian University | Wang S.,Xidian University | Guo Z.,Xidian University | Li B.,Xidian University | And 3 more authors.
Guangxue Xuebao/Acta Optica Sinica | Year: 2012

A surface heat source adjustment approach to calculate temperature field is presented in this paper. In the approach, virtual surface heat source is introduced at the boundary of the object to solve the boundary value problem of the steady-state heat conduction equation. A contact model of rough surfaces with heat conduction connection is established. On this basis, the randomly distributed boundary conditions are established, and the temperature field in the medium is computed by using the surface heat source adjustment method. The result shows that the temperature field presents some random fluctuation due to the untight contact between the actual surfaces. The fluctuation is very obvious near the boundary while it is not obvious at the center, and the smaller the effectively contacted area, the more obvious the fluctuation is. For example, the fluctuation of 50% effective contact is more obvious than that of 75%.

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