In this paper, a new high power solid state laser multi segment amplifier with 29 cm square each aperture has been introduced and was tested at different charge voltage. Under the condition of charge voltage of 23 kV and pumping energy density of 10 0 J/cm 3, the average small signal gain coefficient of 4 99%cm -1 and energy storage efficiency of 3 0% are obtained in experiments.

It is hard to design for beam expander with high power and wide aperture required, because it is shorten length, larger aperture, as well as on axis and off axis aberration must be corrected properly. In this paper,a design method for high power and wide aperture beam expander is talked about. One beam expander is given with clear aperture of 200mm, focal length of 400 mm and field of view of 2 mrad. Image evaluation and system parameter are shown at same time.

The capillary discharge experiment is proceed at capillary charge filled with Ar gas. Output current of 34.3 kA and current pulse rising edge of 40 ns are attained. It is showed that impedance of capillary filled with gas is consisted of resistance and inductance component. And resistance component is far less than inductance component.

This paper proposed and realized a novel all optical pressure sensor. It is achieved by using fiber coupling laser diode (LD) to pump the Nd∶YAG microchip. The pressure was imposed indirectly on the radial direction of the crystal by a pressure transferring device. As a result of the stress birefringence the microchip laser′s longitudinal mode was split into two with different frequency. The frequency splitting signal is coupled into fiber, detected by a photodiode and than changed as a detectable beat frequency signal. There is a direct proportional relation between the frequency difference and the pressure imposed on the microchip, so pressure can be obtained. Moreover, the effect of the modes on the measurement error was finished. A result of 1.31 MHz/kPa was achieved in the experiment, so it can be used in the high sensitivity measurement and has a broad application future.

Based on the summarizing and comparing the analyzing methods in existence for multipath interference (MPI) resulted from backward Rayleigh scattering in distributed fiber Raman amplifiers, two novel methods are presented. A simple analytical expression is developed in the first method. The evolution of optical powers within each step is calculated by a semi analytical method in the second so that the MPI calculating time can be saved and the precision can be improved.

In this paper, the mechanism and the basic theory of producing holographic volume grating within the polymer dispersed liquid crystal film are expounded. Some experiments were conducted to investigate the micro structure of the H PDLC grating, major factors impacting the diffraction efficiency of grating, such as different recipes of PDLC, the degree of two laser beams, thickness of film, exposing time of PDLC cells and the applied voltage. As a result, it is found that the most significant affecting factor is the recipe of PDLC. With the same recipe, shorter cure time, comparative smaller degree of two laser beams and thinner PDLC film give rise to higher diffraction efficiency. Finally, using 17 degree of two laser beams, 10 μm of PDLC film thickness, 50 mW power of laser with the wavelength of 441 6 nm and exposing time about 30 seconds, the efficiency of about 90% of the H PDLC volume grating is obtained.

In this paper the effects of scattering noise on input images for holographic storage in photorefractive lithium niobate crystals have been investigated in detail by means of measurements of loss of signal to noise ratio (LSNR). A variety of lithium niobate crystal samples with different dopants, different doping concentrations, different annealing after growth, and used for different recording geometries are studied. More attention has been paid to the characteristics of scattering noise resulting from object beams. The experimental results show that the effect of scattering noise in oxidized crystals is less significant than that in reduced or as grown crystals. Comparing with transmission and 90° recording geometries, reflection geometry is less subject to the effect of scattering noise.

In this paper, robust face recognition in complex background is concerned. Two main technologies, eigenface and elastic matching, are compared. The information given by key points is used in elastic matching to get better performance. Experimental results with a real face library are presented.

Laser processing was used to deposite TiCp/Ni Cr B Si C composite coatings on 45 # steel. The microstructure and wear properties were investigated by means of SEM, TEM, and wear test. The mechanism of surface modification of La 2O 3 on the composite coatings was also discussed. The results showed that TiC partly dissolved in the laser melt pool during melting. There were twins and dislocations at the interface of particle TiC and matrix due to the solidifying stress. The interdiffusion zone was formed between the coating and matrix. The carbides of (Fe,Cr) 23 C 6, the micro crystal of α and γ were discovered in the interdiffusion zone. The amorphous phase of Ni Si B La was formed at the interface. The wear resistance of coating was affected by rare earths and the content of TiC. The coatings possessed optimal wear resistance when the mass fraction of TiC was 45%～50%.

According to the physics process of powder feed laser cladding, the basic problems are brought up that must be considered in the numerical model for that process. The model of interaction among laser beam, alloy powder and basement, the states of alloy powder particles at reaching the melt pool and the mixing of the particles with liquid metal in the melt pool are especially discussed and analysed.

A new heat treatment method that combines carburizing or siliconizing with laser hardening treatment in the salt solution was adopted. Using this method, the laser hardening treatment can be carried out, during surface carburizing and surface siliconizing. Experimental result shows that after laser carburizing and laser siliconizing, the carbon and silicon content in the low carbon steel 20 # surface increases by twice as original steel. A hardening layer consisting mainly of martensite and bainite structure can be obtained, which surface hardness is 1.5～2 times harder than that of original sample. The wear resistance of laser carburizing and laser siliconizing samples is increased 4～7.5 times as original steel. The test of static corrosion in the 10% H 2SO 4 solution for 240 hours shows that the corrosion resistance of steel 20 # after laser siliconizing is about 40% larger than original steel.

Using the laser diode CW pumping Cr 4+ ∶YAG Nd 3+ ∶YAG combined single crystal microcylinder, the self Q switched laser pulses with the pulse width of 10 ns and the pulse repetition rate of 10 kHz are obtained. The average output power is 18 mW. Theoretical calculated pulse width and repetition rate vs pump power are agree with the experimental results.

The semiconductor laser rate equations are rewritten using a new set of parameters which can all be found from steady state and small signal measurements on the laser. Procedures for finding these parameters are described. Parameters have been measured on 1537.5 nm DFB laser. Comparison between large signal measurements and simulations using the measured parameters shows in general good agreement for modulation currents sufficiently above threshold.

The nonlinear absorptions and optical limiting properties of two nest shaped metallic clusters were investigated with 532 nm, 8 ns duration laser pulses. Z scan and optical limiting experimental results indicate that the nonlinear absorptions and optical limiting properties of two clusters depend critically on the heavy metallic atoms in the two clusters. The effective excited state absorption cross sections were calculated according to effective excited state absorption theory. The optical limiting mechanisms were analyzed.

Based on the single electron approximation and soft core potential model, 1D time dependent ShrAo¨Gdinger equation is solved to investigate the effect of positive and negative chirp on high order harmonic spectrum. It is shown that the harmonic spectrum generated by a positive chirped pulse splits, while that generated by a negative chirped pulse is broadened, which implies that a radiation source as short as attosecond could be produced.

An important parameter characterizing phase conjugation technology used in the powerful laser system is the phase conjugation fidelity. Brillouin enhanced four wave mixing, whose interference beat frequency drives an acoustic field, can improve the SBS phase conjugation fidelity. For the double frequency single cell configuration, using array camera, the experiments are carried out on the phase conjugation fidelity of beam interference driving SBS when the SBS conversion efficiency is optimal.

Based on the Kirchhoff law, according to the relationships between various technical parameters and main specifications (limited temperature measurement sensitivity, temperature measurement accuracy, temperature measurement range), an optimal working wavelength of the practical real time temperature measurement system using laser diode and LiTaO 3 pyroelectric detector is proposed. Experimental results show that both temperature measurement sensitivity and temperature measurement accuracy are suitable for the requirement in the range of 400～1200℃.

A technique for accurate measurement of the refractive indexes of liquid and gas was proposed. The approach, based on Fabry Perot (F P) interferometer and using the central wavelength of transmission spectrum to elicit the measurand, essentially eliminates the errors aroused from light source fluctuation. Such a system was developed. The optical signal was transmitted through fibers, and a tunable optical filter is used to collect the sensing data. Using the test data of refractive indexes of a set of alcohol solution with different concentrations, the analytical relation between refractive index and central wavelength of transmission spectrum was educed with least squares linear regression method, the regression error is less than 0 00005. Refractive indexes of distilled water and acetone were measured respectively; the measuring error is no more than 0 0001.

This article gives a detail study of short pulse heterodyne system about the target distance measurement with carbon dioxide laser radar. It points out the influence of random error on single pulse distance measure precision and the main source of system error. A contrast experiment of far target distance measure was carried out. The pulse trip back time was measured.

A new method of measuring micro vibration was put forward based on the principle of optical fiber resonance. The principle was given and some data from experimentation were got.

In this paper, the effects of chirped fiber grating on optical pulse was analyzed, calculating the broadening of optical pulses after propagating through a certain fiber span and then compressed by a chirped fiber grating, considering the influence those ripples on increasing dispersion power penalty. According to the requirement that dispersion power penalty should be less than 1dB, the relationship between maximum amplitude, period of GVD ripples and system bit rate was investigated.

BY modifying phase mask UV exposure system and inserting a circumvolved device which making optical fiber rotation in back of the phase mask, the PMD in fiber Bragg gratings (FBGs) is compensated. The average differential group delays (DGD) are 18 2 ps and 0.2 ps before and after compensation, respectively. These have already be used to 40 Gb/s OTDM system as dispersion compensators, and polarization mode dispersion (PMD) in 122 km G.652 SMF was successfully compensated by two chirped FBGs in a 40Gb/s OTDM transmission system.

The method of declining Gaussian beam in AWG is introduced. A 4×4 AWG is simulated with this method, and the result is compared with that using BPM method. This method is simple and feasible. It is helpful to optimize the design of devices.