LD End-Pumped Nd:YAG InnoSlab Laser at 1319 nm

The 1319 nm lasers have important research value and application prospects in optical communications, biomedicine and nonlinear frequency conversion. Currently, there are few reports of high power 1319 nm continuous lasers with high beam quality. We have demonstrated a high output power, high beam quality 1319 nm continuous-wave laser by laser diode end-pumped Nd:YAG slab with a stable-unstable hybrid resonator. With a pumping power of 477 W, an output of 96.8 W was obtained with a slope efficiency of 26.5% and stability of 0.27%. A single wavelength laser operation at 1318.7 nm was demonstrated. At an output of 91.1 W, the beam quality factors M2 in stable and unstable directions were 2.95 and 1.88, respectively.

Diode end-pumped self-Q-switched and mode-locked Nd,Cr：YAG /KTP green laser

We first experimentally demonstrate a laser-diode end-pumped self-Q-switched and mode-locked Nd,Cr：YAG green laser with a KTP crystal as the intra-cavity frequency doubler. The device produces an average output power of 680 mW at 532 nm. The corresponding pulse width of the Q-switched envelope of the green laser is 170 ＋ 20 ns. The mode-locked pulses have a repetition rate of approximately 183 MHz and the average pulse duration is estimated to be around sub-nanosecond. It is found that the intra-cavity frequency doubling greatly improves the modulation depth and stability of the mode-locked pulses within the Q-switched envelope.

Optical coatings for fiber lasers

Fiber laser is the future development direction for the high energy lasers. This paper describs two kinds of optical coatings for fiber laser, including long and short wave pass filters. The one characteristic of fiber laser coatings lies in that coatings should separate two closely wavelength light including laser pump wavelength (980 nm) and laser irradiation wavelength(1 050～1 100 nm). At the same time, the coatings should have high laser damage threshold.

Green Output of 1.5 W from a Diode-Pumped Intracavity Frequency-Doubled Self-Q-Switched and Mode-Locked Cr,Nd：YAG Laser

We report a diode-pumped intracavity frequency-doubled self-Q-switched and mode-locked Cr,Nd：YAG/KTP green laser with a Z-type cavity, which produces 1.5 W of average power at 532nm with incident pump power 14.2 W. The individual mode-locked green pulse duration is about 560ps with 149 MHz repetition rate. Almost 100% modulation depth of the mode-locked green pulses is achieved at an incident pump power of 4.13 W. The maximum energy of Q-switched green pulse is 19.8μJ. The experimental results of pulse duration and pulse energy of Q-switched green pulse agree well with the theoretical calculations.

Preparation and Characterization of Hg_(0.8)Cd_(0.2)Te Epilayers Grown by Hot Wall MOCVD

Hg_(1-x)Cd_xTe(CMT)epilayers with corresponding wavelength of 10.6μm(x=0.2)were reproducibly grown on GaAs substrates in a movable hot wall MOCVD reactor.Rather high uniformity of solid compo- sitions was obtained.X-ray diffraction,TEM,DCXD,FTIR and Van der Pauw technique were employed to determine the crystalline,optical and electrical properties of CMT epilayers,which are effectively im- proved as compared with the previous data.

Influences of annealing temperature on properties of Fe^2+:ZnSe thin films deposited by electron beam evaporation and their applications to Q-switched fiber laser

Fe^2+:ZnSe thin films are prepared on sapphire substrate at room temperature by electron beam evaporation and then annealed in vacuum(about 1×10^-4 Pa)at different temperatures.The influences of thermal annealing on the structural and optical properties of these films such as grain size and optical transmittance are investigated.The x-ray diffraction patterns show that the Fe2+:ZnSe thin film is preferred to be oriented along the(111)plane at different annealing temperatures.After the film is annealed,the full-width-at-half-maximum(FWHM)of the x-ray diffraction peak profile(111)of the film decreases and its crystal quality is improved.Scanning electron microscope images show that the films are more dense after being annealed.Finally,the sample is used as a saturable absorber in ZBLAN fiber laser.The annealed Fe^2+:ZnSe thin films can be used to realize stable Q-switching modulation on ZBLAN fiber laser.The results demonstrate that the Fe2+:ZnSe thin film is a promising material for generating the high-power pulses of mid-infrared Q-switched fiber lasers.

Observation of Antiphase State in a Self-Q-switched Nd,Cr：YAG Laser

We experimentally investigate the antiphase dynamics phenomenon in a self-Q-switched Nd, Cr：YAG laser operating at 946 nm. Due to the effect of spatial hole burning, the Q-switched pulses sequences of one, two and three modes at different pump power are observed. The experimental results show that the pulse sequences display classic antiphase dynamics.

Growth and x-Ray Diffraction Study of a New Laser Crystal Nd^(3+): NaY(WO_(4))_(2)

A new laser crystal Nd^(3+):NaY(WO_(4))_(2) up to 10x10x20mm with low threshold can be obtained from the system of(WO_(4))_(3)-Na_(2)WO_(4) by top-seeded solution growth method.The crystal rod of Ф2,5×5mm was pumped by xenon Hashlamp and 1.06/zm laser output was gained.Using a D/max-rA type diflractometer,the x-ray powder diffraction data of NaY(WO_(4))_(2) were obtained.

Compensated methods for networked control system with packet drops based on compressed sensing

Due to unreliable and bandwidth-limited characteristics of communication link in networked control systems,the realtime compensated methods for single-output systems and multioutput systems are proposed in this paper based on the compressed sensing(CS)theory and sliding window technique,by which the estimates of dropping data packets in the feedback channel are obtained and the performance degradation induced by packet drops is reduced.Specifically,in order to reduce the cumulative error caused by the algorithm,the compensated estimates for single-output systems are corrected via the regularization term;considering the process of single-packet transmission,a new sequential CS framework of sensor data streams is introduced to effectively compensate the dropping packet on single-channel of multi-output systems;in presence of the medium access constraints on multi-channel,the communication sequence for scheduling is coupled to the algorithm and the estimates of the multiple sensors for multi-output systems are obtained via the regularization term.Simulation results illustrate that the proposed methods perform well and receive satisfactory performance.

Coupling Frequency Band of the In-Phase Locked Gain Waveguide Array Lasers

A coupling frequency band of an in-phase locked sliced gain waveguide array laser is experimentally investigated.The experimental data show that for an in-phase locked single peak intensity distribution output without side lobes of the sliced gain waveguide array laser,there exists a coupling frequency band and the coupling frequency band increases as the transmissivity of the laser output coupler decreases.

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

The three-dimensional （3D） pump intensity distribution in medium of the laser diode （LD） pumped high average power heat capacity laser is simulated by the ray tracing method, and the divergence characteristics of fast axis and slow axis of LD are simultaneously considered. The transient 3D temperature and stress distributions are also simulated by the finite dement method （FEM） with considering the uneven heat source distribution in medium. A LD face-pumped Nd：GGG heat capacity laser is designed. The average output power is 1.49 kW with an optical-optical efficiency of 24.1%. OCIS codes： 140.3480, 140.6810, 120.6810, 000.4430.

Diode-pumped self-Q-switched Cr,Nd:YAG laser with 7-W average output power

We report a diode-pumped self-Q-switched 1064-nm Cr,Nd：YAG of 16-18 ns. The maximum average output power up to 7 W, 3370, is obtained in a simple and compact linear cavity by using transmittance of 1570. The laser operates at TEM00 mode with a laser with pulse duration in the range corresponding to a slope efficiency of a plane-concave output coupler with a pump power of 14.2 W.

Laser ablation and structuring of CdZnTe with femtosecond laser pulses

We report an experimental investigation on laser ablation and associated surface structuring of CdZnTe by femtosecond Ti:Sa laser pulses(laser wavelengthλ≈800 nm,≈35 fs,10 Hz),in air.By exploiting different static irradiation conditions,the fluence threshold and the incubation effect in CdZnTe are estimated.Interestingly,surface treatment with a low laser fluence(laser pulse energy E≈5-10_μJ)and number of shots(5<N<50)show the formation of well-defined cracks in the central part of the shallow crater,which is likely associated to a different thermal expansion coefficients of Te inclusions and matrix during the sample heating and cooling processes ensuing femtosecond laser irradiation.Irradiation with a larger number of pulses(N≈500,1000)with higher pulse energies(E≈30-50μJ)results in the formation of welldefined laser-induced periodic surface structures(LIPSS)in the outskirts of the main crater,where the local fluence is well below the material ablation threshold.Both low spatial frequency and high spatial frequency LIPSS perpendicular to the laser polarization are found together and separately depending on the irradiation condition.These are ascribed to a process of progressive aggregation of randomly distributed nanoparticles produced during laser ablation of the deep crater in the region of the target irradiated by a fluence below the ablation threshold with many laser pulses.

可饱和吸收镜制造误差及其对飞秒激光器腔型设计的影响（英文）

目的:从可饱和吸收镜(SESAM)制造误差所引起其光学特性的改变出发,提出采用飞秒激光器腔型设计的方法,避免SESAM误差对激光输出性能造成的影响。创新点:从激光器腔型设计方案出发,采用不同曲率镜,调整激光腔中激光晶体及可饱和吸收镜上的光斑半径大小比值,解决SESAM制造误差对激光器输出的影响。方法:采用传递矩阵法计算SESAM半导体膜层厚度对其光学性能的影响。对于不同的SESAM设计,影响大小不同(表1)。结论:通过改变腔内曲率镜M1,M2和M3的曲率值大小以及腔的长度值,可以减弱SESAM制造误差对飞秒激光器输出的影响,实现对所有SESAM的连续锁模。

Mode characteristics of nano-width rectangle resonator

A new method based on Maxwell＇s equations,ABCD ray matrices,and total internal reflection is proposed to theoretically analyze the characteristics of eigenmodes confined in nano-width rectangle resonators.Using this method,mode wavelengths and indices of transverse and longitudinal modes are obtained.Another method based on the finite difference time domain technique and Pad′e approximation is used to numerically calculate resonant wavelengths,mode field distributions and quality factors.The results of two methods show that the resonant wavelengths obtained from both methods are very close,and the maximum relative error is less than 2%.The mode indices of transverse and longitudinal modes obtained agree well with mode field distribution patterns calculated by finite difference time domain techniques.

Spatial and temporal distribution of Q-switched laser pulses in multimode regimes

The spatial and temporal distribution of Q-switched diode-pumped solid-state laser （DPSSL） pulses is investigated in multimode regimes. A theory model of spatial and temporal distribution of multimode Q- switched DPSSL pulses is established. The influences of position, initial inversion population density, and mode ratio on pulse width are studied. The results show that the pulse expands in the position wherein two or more mode intensities are equivalent, and the pulse building time difference of the modes are less than one mode pulse width. These results can be applied in pulse compression and mode composition.

Random lasing in strongly disordered medium

Using the time-dependent theory, we calculate the random-laser emission spectra in a two-dimensional strongly disordered medium. The calculation results show that in low dimensional systems, such as thin- film disordered media and planar waveguides, the larger the difference of the refractive indices between the scattering and background media, the smaller the lasing threshold. We also reveal the existence of multi-mode survival and mode competition. We experimentally obtain the emission spectra of a dye solution with Al particles doped at different pumping energies, and the experimental results agree well with the calculated ones.