Based on the analysis of frequency spectrum of Faraday angle in blue and violet light ranges for BiAlDyIG materials, we have perpared a fine quality BiAlDyIG thin film by a pyrolysis method and crystalized the film with rapid recurrent thermal annealing. The effective Faraday angle of RRTA sample is over about 0.5 degree larger than that of the common samples, and its Faraday angle increases with the number of recurrent annealing increasing, which is due to the finess of the grain and many Bi 3+ -O 2- -Fe3+ are informed. Meanwhile, the concentration variation of Al3+ions in octahedral and tetrahedral sites results in a decrease of curie temerature (140～160℃). These results are very promising for improving the recirding density and signal-noise-ratio.

This paper describes a fourth harmonic system for a 1 06 μm laser using nonlinear optic crystals, which are a frequency doubling KTP crystal and a frequency quadrupling LAP crystal. Using computer simulation, we have got optimal parameters of the harmonic device. Some parameters of affecting the harmonic conversion efficiency, phased matching, maximum direction of the effective nonlinear coefficient and threshold power are discussed. This fourth harmonic system offers wide applications to the diagnostics of the soft X-ray ps streak camera and framing camera, nonlinear optics and other ultrafast phenomena study. Finally, a 5 ps ultrashort UV laser has been generated and measured using astreak camera.

The experimental studies of influnce of laser coherence induced by the resonant cavity length modulation is introduced in this paper. A theoretical analysis shows that the influnce mechanism is the random vibration of the resonant cavity mirror induced with the PZT.

With all utensils made in China we have successfully manufactured a broadband Er 3+ doped fiber superfluorescence source. The basic characteristics of the superfluorescence source, such as the output power, output linewidth, and the change of the linewidth with temperature, have been analyzed and studied. And rather good experimental results have been obtained. To address directly the question why the natural fluorescence spectrum of the broadband source has a pinnacle structure which results in a too narrow linewidth, we present a simple but effective measure to restrain the pinnacle. Consequently, a spreaded frequency spectrum with a satisfactory width has been obtained.

Instabilities and self switching in a nonlinear directional coupler with single input excitation are discussed. The approximate analytical solutions to the nonlinear coupling equation near the critical power are obtained.

The varying character of the curvature of a water cooled mirror′s surface with varying coolant pressure has been studied. The wavefront aberration of the mirror after pressure deformation has also been analyzed. It is shown that the focus variable mirrors with varying coolant pressure are suitable for the middle infrared laser system.

The combination of optical real time parallelism with computer′s flexibility can implement real time optical image morphology parallel processing. In this paper a real time optical processing system with a mathematical morphological new approach of optical frequency filtering for complex valued kernel structure element to implement binary image real time parallel processing is proposed.

The newly synthesized push pull azobenzene compounds were doped in the PMMA film. Their multiple storage characters were studied. The excellent real time and long time double image storages were obtained. The associative memory image storage was achieved. Furthermore, the storage mechanism is explained.

This paper puts forward a method based on Mie scattering theory, which detects the lateral scattering light from a new view point. A novel theoretical calculation model is established. According to this principle the measuring range of particle sizes is extended while technical requirements are reduced. Combining with mature semiconductor lasers and the CCD image technique, this method will make the particle sizer portable and more sensitive.

The influence of assistant gases on the thresholds of laser induced plasma shielding was studied by using a 20 kW CO 2 laser processing system to weld low carbon steel. The results demonstrate that the critical power densities of laser induced plasma shielding for different assistant gases are in the order from low to high values as following: Ar→N 2→CO 2→He. The plasma shielding threshold could be as low as 1.85×10 6 W/cm 2 when argon was used as the assistant gas in our experiment. The influence of gas on the threshold of plasma shielding depends mainly on the thermal conductivity and dissociation energy of gas, while the influence of ionization enetgy is the secondary compared to the thermal conductivity and dissociation energy. The low power density of plasma shielding in argon is dominantly due to the poor thermal conductivity of argon which causes that the LSC wave can easily overheat and propagate.

A kind of the laser and CCD optigonometry automatic position shifting measuring method for the auto body 3 D curved surface shape is presented in this paper. The principle and the measuring process of the method are analyzed. The expermental system is described. The results of the experiment are provided and have shown that the measurement method and system may be practically valuable.

A blue-violet laser is described by direct laser diode frequency doubling with a new nonlinear organometallic complex CMTC crystal. At room temperature, a blue-violet light output of 11.8 mW (λ=404 nm) is realized. With a 4 mm-long crystal, a SHG conversion efficiency of 0.60% (λ=808 nm) is obtained.

A Nd:glass slab oscillator and two stage amplifier system has been built up. Using a novel Cr 4+ :YAG colour centre crystal, the Q switching experiments, have been performed. After two stage amplifications, the near diffraction limit beam quality of M2x=M2y=1.5 and energy amplification of 10.1 have been achieved.

A hybrid semiconductor laser is fabricated by combining an anti reflection coated F P laser chip with an in fiber Bragg grating (FBG). The cavity length is about 3 cm and the peak reflection of the FBG is 50%. At a bias of 50 mA, the output is 1 mW with a side mode suppression ration of 37.6 dB. A simple theoretical analysis is also given.

The preliminary experimental results of the generation of the 1.871 μm laser oscillation from a monomode Tm 3+ doped silicate fiber pumped by a 1.053 μm laser is reported. The maximum output power is 153 μW, and the slope efficiency is 0.32%.

The excitation of plasma wake wave and acceleration of electrons after interaction between a high intensity ultrashort laser and underdense plasma using a particle in cell simulation is numerically studied. The results show that wake waves can be excited after the interaction between the single frequency or beat wave laser and underdense plasma, but the wake wave has larger strength and longer wavelength, then it can more efficiently accelerate electrons.

This paper describes the experimental setup of a Fourier transform intracavity laser absorption spectrometer (FT ICLAS). The advantages of the spectrometer over the traditional ICLAS grating spectrometer are also discussed.

If only the first order correction to the scalar paraxial field is concerted, then the field can be expressed as =[ε x,0,ε z] and the longitudinal field energy E z is proved to be constantly independent of the position z of the beam cross section. The value of E z stands for the degree of scalar paraxial approximation. An approximation factor η is suggested to characterize this property. The larger η, the worse degree of the approximation. Results are applied to super Gaussian beams.

The asymmetry of the signal is one important character of the self mixing interference effect, which leads to the possibility of directional discrimination in the Doppler velocity measurment or displacement measurment. Theoretical models are given by using a two mirror cavity model, which explains the asymmetry of the self mixing interference signal successfully. Simulation results are given which are consistent with the experimental ones.

In this paper, the effects of density of localized exciton states on stimulated emission processes have been reported. In our experiments, two samples of Zn x Cd 1-x Te ZnTe mutiple quantum wells which with different concentration are employed, and the stimulated emissions from the localizid states are observed in each of them. The density of localized exciton states in Zn 0.67 Cd 0.33 Te ZnTe MQWs is much greater than that in Zn 0.78 Cd 0.22 Te-ZnTe MQWs. The stimulated emission processes was found to be an exciton-ecciton scattering processes, but it was not found in Zn 0.78 Cd 0.22 Te-ZnTe MQWs. It seems to be very important for localized exciton to create stimulated emissions, but too high density of localized exciton states may greatly affect the stimulated emissions.

A graphite target was ablated repetitively by a pulsed Nd:YAG laser. At the constant laser energy, laser photoacoustic strength decreases with the increase of the repetitive times, which indicates that the ablation caused hole plays an inhibitive role in the reduction of flows of energy and of the mass from the sample.