Two kinds of improvement, ST improvement and ST-input-output improvement, on Yang-Gu algorithm have been proposed to design diffractive optical elements (DOE) used for beam shaping in this paper. These kinds of improvement can provide less sensitivity to the initial phases, better shaping quality, and higher iterative convergence efficiency. The validity of the two kinds of improvement is proved mathematically, and is shown by simulation of the practical design. Further, the ST-input-output improvement can mitigate the contradiction among the different parameters in beam shaping.

A practical and feasible tuning scheme for fiber Bragg grating by electromagnetic force is reported. In the experiment, a tuning range of 1.38 nm was obtained under 300 mA current. The restoration of tuning is quite good. The tuning scheme can be used in re-configurable optical add/drop multiplexer (ROADM), external-cavity fiber lasers, and fiber sensors based on wavelength modulation.

This paper analyzes the necessity of fast protection for capacitor bank with high specific storage used in SG-Ⅲ high power laser. A technical scheme with inductor and tailor-made fuse was proposed. Especially the design of fast protective fuse was introduced. The experiments demonstrated that the fast protective fuse can take action within a quarter of first cycle of current and limit the voltage reversal under 10%. The design of the protection can meet the project requirements and can reduce the damage of PPS to the lower extent and provent the personnel safe and collateral property from the all threats.

An adaptive beam expander to control the focusing characteristics of flying optics, was proposed and its operating principle and adjusting characteristics were analyzed. The simulation results indicate that the adaptive beam expander can be used to control the focusing length and spot size.

When a high power laser beam propagates through a multi-stage amplifier, distances separating different stages play an important role in deciding the characteristics of the output beam. The concept of the relative intensity noise (RIN) has been adapted to quantitatively analyse the experiment results.

Using MTT to study the influence of He-Ne laser irradiation on proliferation of spleen cell and thymus cell with SP2/O marrow tumour mice. The result shows that the laser can enhance the activation of immune cell, as compared with the control group (P<0.01). This demonstrates that laser irradiating immune organ region has enhanced lymphocyte activation, promoted DNA duplication and increased immune function.

In this paper, a new method for target recognition, normalized fringe-adjusted joint transform correlation is proposed. Analysis shows that the method can work more effectively. Simulation results show that, compared with NJTC and JTC, the correlation peak is more obvious, sharper; compared with FAF JTC, the anti-noise ability is greatly increased; and simulation shows that in 0 to 0.2 noise level, the new method increases PBR, and discrimination; the output is stable under different illumination.

A new method of image recognition is proposed in this paper. It realized the straight double-JPS interference of the JPS of input identifying image and reference one, and didn′t need special optical components and improving the JPS variedly either. The experiment showed that in the double-JPS interference of the same images the fringes appeared, but no fringes in the different images condition.

In this paper, the characteristic recognition vector and the template matrix are proposed for image recognition based on volume holographic storage image-databases, which include the effect of the non-uniform diffraction efficiency upon the recognition accuracy. With such vectors and the matrices, the comparison study has been performed experimentally about several recognition algorithms, and it is found that the scheme of correlation coefficient is optimum.

By means of combining the real-time holographic device and the acoustic source testing device, a new tool for experimental earthquake simulation research is developed. The stress fields and its variations in the specimen are recorded by real-time holographic interferometry while the wave-forms of ultra-sonic waves stimulated by the micro-cracks are recorded by a transient automatic wave-form recorder to determine the time, location and intensity of the micro-cracks. Some noticeable phenomena have been observed in the experiment, the elastic strain and plastic strain can be visualized clearly and can be recorded in high resolution by this method as well as the generation and extending of cracks.

The experimental results of 74 mW red laser at 671 nm have been observed with 1 W diode pumped Nd∶YVO 4 laser and type-Ⅰ critical phase matching of LBO crystal. The analyses and experiment show that the double frequency by critical phase-matching is the useful method to obtain high efficiency solid-state red laser.

In this work, InGaAs/GaAs multi-layers quantum dots are grown by using MOCVD technique and ridge-like stripe structures are fabricated. It is shown that the threshold current density is dependent on the QDs structure. The threshold current density is greatly lowered by using multi-layers quantum dots, coupled QDs layers and wide band gap barriers. The minimum average threshold current density of 20 A/cm 2 is achieved. The lasing wavelength is also dependent on the active region. With increasing the number of QDs layers, the lasing peak will move to long wavelength end.

A new phenomenon that the output of a laser diode does not change with the injected light intensity which is modulated when its injection current is certain values has been found. The amplitude of output change of the laser diode varies periodically with the increase of the injection current. It is made clear through the theoretic analysis that this phenomenon is caused by stimulated emission and interband carrier absorption that depend on the longitudinal mode competition, thermal effects, and so on.

Using the equivalent external cavity approximation, a theoretical model of fiber grating external cavity semiconductor laser (FGECL) has been presented after taking into account the reflectivity distribution of fiber grating. The numerical analysis shows that the obtained mode suppression ratio (MSR) by the model is obviously lower than that by regarding the reflectivity distribution of fiber grating as a dot function.

By using a phase-shifted fiber grating instead of an uniform grating and an expensive circular as narrow-band filter, and a Mach-Zenhder fiber filter as wide-band filter, and integrating the effect of saturable absorber of the unpumped doped fiber, a single-frequency Yb 3+ -doped fiber ring laser operated at 1053 nm is obtained.

By using Wigner distribution function, the beam combination characteristics of general astigmatic Gaussian beams are studied. The analytical formulas of intensity profiles and beam propagation factor (M2) for incoherent and coherent combinations are derived. The analytical and numerical results show that the beam quality of the resulting beam depends on the number, normalized separation distance and geometrical arrangement of beamlets. The beam quality of the coherent combination is better than that of the incoherent combination when the beam propagation factor (M2) is chosen as the criterion, whereas the beam quality of the coherent combination is not always better than that of the incoherent combination, if the power in the bucket (PIB) is adopted as the criterion.

A model of an open ladder-type three level noninversion lasing system is presented in this paper. A steady state linear analytical solution, and the effect of the probe and driving fields detunings varying on the noninversion lasing gain, dispersion and population difference are investigeted. It is found that the open ladder-type system can obtain the noninversion lasing gain much bigger than that obtained in the corresponding closed ladder type system; the variation rule of the gain, dispersion and population difference in the open ladder type noninversion lasing system is much different from those in the open Λ-type and simple three level noninversion lasing systems.

Low pressure DC flowing discharge is used to study the formation of XeI  excimer in mixture of Xe/I 2. Fluorescence emission at spectral regions of 240～270 nm is examined. The characteristics of the emission spectra of the excimer and 253 nm intensity formed from mixture for different total gas pressures are reported. The investigation shows that 253 nm fluorescence intensity is the largest at 333 Pa and the correlated electron temperature of discharge plasma is 13.2 eV. The major reaction channel is Xe being excited to  3P by impact of high speed electron, and then XeI(A,B,C) being formed by collision between Xe( 3P) and I 2.

The magnetic-field gradient in axis of an ant-Helmholtz coil in a dilute Rb vapor through observing fluorescence while laser frequency sweeping is measured. The result is checked by using other method and is compared with the calculation. All phenomena could be understanded by considering nonlinear magnetic susceptibility.

Nonlinear refraction and optical limiting properties in the novel nanocomposite based on C 60 structured system with gold nanoparticles were investigated by Z-scan technique and optical limiting experiment with Q switched, double frequency ns/ps Nd∶YAG laser pulses. The experimental results show that the nonlinear refraction mainly results from the surface plasmon resonance of gold nanoparticles in the nanocomposite. The optical limiting properties of the nanocomposite is stronger than that of C 60 toluene solution. The optical limiting mechanisms were discussed.

This paper proposes a novel resonant cavity enhanced (RCE) photodetector with a flat-top and steep-edge response, which is promising for WDM application. The simulated response curve has a bandwidth of 1.8 nm at 0.5 dB down from the peak, 5.6 nm at 10 dB down from the peak, 10.4 nm at 20 dB down from the peak, and a peak quantum efficiency of 99.7%, the ripple in the flat-top is negligible.

A new method of phase-modulated excimer laser crystallization to fabricate the three-dimensional nc-Si array within the a-Si∶H/a-SiN x∶H multilayers (MLs) is adopted. The results of atomic force microscopy (AFM), micro-Raman measurements and cross-section transmission electron microscopy (X-TEM) demonstrated that the crystallized sample shows a three-dimensional ordered structure of nc-Si with the average size of about 3.6 nm, which has longitudinal order with 14 nm periodicity confined by SiN x sublayers in the MLs, and lateral order with 2 μm periodicity by patterned local crystallization.

Super resolution, which allows the readout of information beyond the optical cutoff frequency given by 2NA/λ, is an alternate way to increase the recording density without the need to directly reduce the spot size by increasing NA and reducing λ. Ge-Sb-Te is a kind of phase-change optical recording material with good performance. It may used to be mask layer in the super-resolution optical disks. In this paper, the relation of the optical parameters (reflectivity and R m/R c) and the film thickness of the structure of the multi-layers of read-only super-resolution optical disks were studied with method of eigenmatrix of multi-layer films. The ideal result of thickness for each layer is given. The read-only super-resolution optical disks were fabricated by RF magnetron sputtering technology. The optical properties were measured.