In order to overcome the influence of amplified spontaneous emission (ASE) on the amplified pulse in the femtosecond laser amplifier, it is an effective way to move the Ti∶sapphire from the waist in the cavity to where the size of the beam is largest. The experiments are carried out on such a new-style folded linear Ti∶sapphire amplifier cavity with the large beam size. The relationship between the beam size and the cavity parameters is calculated and the beam size distribution in the cavity is provided. The systemic experiments are done on the relationship between the output power and the cavity parameters such as the radius of the curved mirror, the reflectivity of the output mirror, the length of the two arms and so on.

Pulse laser performance of Nd∶GdVO 4 crystal is investigated by using xenon-flash lamp as pump source. The dimension of the laser crystal sample is 4 mm×4 mm×6 mm. With output coupler transmission of T=15%, static output energy of 31.7 mJ is obtained at the pump energy of 6.32 J. For T=7% output coupler, the pump threshold of the laser is 0.13 J. The passively Q-switched operation is achieved by using 1.5 mm thickness Cr 4+∶YAG wafer with small-signal transmission of 54.7%. The dynamic-static laser output ratio is about 1:3. With T=15% output coupler, single laser pulses with duration of 48.0 ns and 39.2 ns are acquired at the pump energy of 3.89 J and 6.32 J, respectively.

In this paper, a technology on generation of ultrashort pulse with high extinction ratio is studied. The pulse from gain-switched DFB laser is linearly compressed in dispersion compensation fiber (DCF), then modulated synchronously by an electro-absorption modulator (EAM) by using the nonlinear absorption characteristic of EAM. With this method, ultrashort of 10.4 ps pulse with repetition rate of 10 GHz, low timing jitter, high extinction ratio and no pedestal is generated experimentally. The technology can be used in 40 Gbit/s optical time division multiplexing (OTDM) system. Also the result shows the ability of pulse shaping of EAM.

A near-infrared spectrometer based on an integrated optical acousto-optic tunable filter (IAOTF) is constructed. In this paper, the characteristic equation and resolution of this kind of spectrometer is first theoretically analyzed, and then the coupling light of three distributed feedback (DFB) lasers centered at different wavelengths, is used as the light source and the emitting spectrum is achieved. At last, data recovery is done with Fourier deconvolution method to improve the resolution of the spectromter to 0.6 nm.

The surface ripple modality of Si/Ge material 1 06 μm laser-induced is measured by optical microscope. It indicates that the subsequent laser will cause positive feedback to increase the ripple after the appearance of laser-induced materials' initial ripple. When power density of laser beam is close to damage threshold, periodical ripple will present on surface of the material; and when the density exceeds damage threshold, stochastic distribution will appear in melting area of the material. The surface ripple modalities occur on Si and Ge materials whose characteristics are dependent on the material property, surface status. At the same time, the infections of the surface ripple structures are analyzed for the laser beam propagation characteristics and the damage effects of laser beam interactions with materials.

To describe femtosecond laser ablation on metal surface, the double-temperature equation (DTE) was formatted simply. In this paper, numerical simulation for temperature field of femtosecond-picosecond pulse laser ablation on metal surface is performed by finite-difference method (FDM). It is reasonable to make the DTE simple in femtosecond scale. It is also analysed that the effect of electron-lattice couple coefficient g on surface temperature, and found that g determines the surface temperature rising rate and the electron-lattice couple time. Compared with picosecond pulse laser, the intense of pulse is the main factor of the finally temperature of electron. The ablated depth of femtosecond laser can be controlled as thick as the surface depth of metal.

The waveplate is a usual but important component in optical system. Generally, λ/2 (or λ/4) waveplate is work at specifically wavelength. If the wavelength of the wave is not match to that of the waveplate, the phase retardation of wave would not π (or π/2). The broadband waveplate which the phase retardation is same in its bandwidth is widely used in spectrum shaping, laser tuning and optical communication. In this paper, an infrared three-stage waveplate is designed with the feature of wide band and high-resolution by the aid of computer simulation. The result of experiment turns to be high consistency with the design. The appropriate wavelength range of the waveplate is 1200～1650 nm. The central wavelength is 1390 nm. The phase retardation for λ/2 complex waveplate is 180.0°±3.6° and 90.0°±3.6° for λ/4 ones.

Langmuir-Blodgett Film of a novel material which contain Schiff-base and naphthalimide has been made and characterized by using the surface pressure-area (π-A) isotherm line and UV-visible absorption spectra. The breakdown pressure of the monolayer was about 30 mN/m. The area occupied by each molecular was about 1.8 nm 2. The π-A isotherm line shown a steep solid field which demonstrated that this molecules could form a good monolayer on the water surface. The UV-visible absorption spectra shown that the molecule could be deposited onto solid substrate. The transfer ratio was kept in the range 1±0.1. The second-order nonlinear optical properties have been investigated by using second harmonic generation (SHG) technique in Langmuir-Blogett monolayer. The dependence of SHG intensity on the incident angle of fundamental is measured beam. A maximum in SHG intensity was obtained at the incident angle of 60°. The second order nonlinear optical susceptibility χ(2) is about 1.51×10-9 esu. The origin of second harmonic generation is attributed to the conjugation system formed by phenylenevinylene.

The model of the vertical cavity surface emitting laser (VCSEL) was established by SIMULINK and the influence of the spontaneous emission factor on the high frequency and large signal modulation response is studied. The result shows when its value varied from 5×10 -3 to 5×10 -5, with the modulation index deepening, the peak photon density will exhibit bifurcation and multi-period, then go back to single period. But if it reduces to 10 -5, the peak photon density will exhibit chaos at last. Furthermore, the position of the bifurcation occurs is depend on the value of spontaneous emission factor. A large spontaneous emission factor can suppress the nonlinear behaviors of VCSEL. The simulation results are agree with the experimental results reported in document.

The growth of ZnCdSe/ZnSe quantum well on N-treated Si substrates which were covered with ZnO by low-pressure metalorganic chemical vapor deposition (LP-MOCVD) was made. Prior to the growth, the Si substrates were treated with NH 3-passivate method, and then ZnO layer was deposited by plasma-enhanced chemical vapor deposition (PECVD) on the passivated Si substrates, X-ray measurement indicated that single orientation ZnO (0002) film was obtained. On these ZnO-Si substrates, ZnCdSe/ZnSe quantum wells were cnsequently grown by LP-MOCVD. There were multi-peaks in the Raman resonant spectra (RRS) of ZnCdSe/ZnSe quantum wells with different well width. PL investigations showed that the emission peak of the QW structures located at about 520 nm, at RT. However, the luminescent signals of the ZnCdSe/ZnSe quantum wells grown directly on Si substrates were undetectable. This indicated that using NH3-passivate Si substrates covered with ZnO film is an effective way to improve the quality of ZnCdSe/ZnSe quantum well.

The GeO 2 dielectric hollow waveguide structure and the related Miyagi equations are introduced in the report. The transmitting losses of the HE 11 mode in straight and bending GeO 2 dielectric hollow waveguide are analyzed by comparing the curve achieved by the means of Miyagi′s equations with the experiment results. The output energy distribution of straight and bending GeO 2 hollow waveguide are given too.

In this paper, a double-integrating-spheres system, basic principle of measuring technology of ray radiation, optical model of biological tissues were used to study the optical properties of human tissues. The results of measurement showed that the parameters of optical properties of human normal bladder and human bladder cancer tissue at 808 nm laser and the linearly polarized laser in Kubelka-Munk two-flux model had prominent distinction (P0.05) which showed that the depolarization of humanbladder cancer tissue to 808 nm linearly polarized irradiation was very big. The parameters of optical properties of humannormal small intestine tissue at 808 nm lase rand the linearly polarized laser irradiation had all prominent distinction (P<0.01), which showed that the depolarization of human normal small intestine tissue to 808 nm linearly polarized irradiation was smaller. Distribution of light intensity of three kinds of human tissues at 808 nm laser and the linearly polarized laser irradiation in Kubelka-Munk two-flux model had obviously dissimilitude.

Holey fiber (HF) can have high nonlinearity and very flexible dispersion. The zero-dispersion wavelength (λ 0) of HF with high nonlinearity can be adjusted by changing the structure parameters of PCF. This can used to generate high efficient optical parametric amplification (OPA) at desired wavelength in HF. Hermite-Gaussian functions have been used to calculate the zero-dispersion wavelength of hexagon HF, calculations show that when pitch is between 1.1 μm and 2.6 μm, the λ0 of HF is around 1.55 μm, and the relation of pitch vs air hole diameter at λ0 has been given. Simulations of the OPA in HF show that gain of OPA can reach 60 dB in only 20 m HF with pump power of 10 W, or the bandwidth of OPA can reach 300 nm.

The arrayed waveguide grating (AWG) has greatly prospective in optical communication as a wavelength filter. Crosstalk is one of the most important factors which block the wide use of AWGs. In order to reduce the crosstalk of an AWG, a new method was proposed and studied in this paper. In this method, the output minimum of a channel is located at the center of the waveguides of other channels and there is no sidelobes of the channel in the waveguides of other channels in the mean time by adjusting the free spectrum range (FSR) of AWG, foca length of Rowland circle and the number of the waveguide array. Thus the crosstalk of an AWG, pecially the adjacent crosstalk can be reduced greatly. Numerical approaching of 1×16 AWGs with different FSR by beam propagation method (BPM) shows the adjacent crosstalk can be reduced about 5.7 dB by this method.

The point-matching method is extended to analyze a travelling-wave electrode structure for ridge-type LiNbO 3 optical modulators. The potential function is expended in terms of a Fourier sine series, and the coefficients of the series are obtained by satisfying the boundary conditions in the contact plane at a finite, discrete set of pints. The calculated fields are used to estimate the characteristic impedance and microwave effective index. This method provides a simple and fast approach to the quasi-static analysis of the multi-layered structures with finite electrode thickness. The results agree well with those obtained using the finite-element method. Some significant conclusions are made for design and optimization of modulators.

Fused planar 3×3 single mode fiber coupler is very important in optic switch, optic buffer, optic resonator and optic filter etc, both the evolution of polarization and the performance of wavelength are the crux. Based on the coupled-mode equations, the theoretical analysis of a fused planar 3×3 fiber coupler was presented. It is not coupling field but optic fiber pigtail operating on the evolution of polarization. The appropriate distance of the cores of the fiber (it is 12.5 μm to us) is obtained via analyzing the relation between the spliting ratio and wavelength. And the fused planar 3×3 single mode fiber coupler is fabricated which has long coupling field by moving flame. The experiment results indicate that the splitting ratio of output of coupler has little change when the wavelength of the input optic range from 1.500 tp 1.575 μm, the experiment results are in good agreement with the theoretical analysis.

The optical pattern recognition is realized by optical correlation, the traditional optical correlation judge the similarity degree of two images by their correlation peak. The fractional Fourier transform contains the spatial information and the spatial-frequency information simultaneously. The fractional correlation can be used to optical pattern recognition too. To overcome the defect that the traditional optical correlator can not recognize images with small differences, a new method based on the fractional correlation was proposed. The theory of the photoelectric hybrid system for realizing this method is given. The simulated results showed that by adjusting the fractional order p, the correlator can not only recognize nearly identical images efficiently, but also provide the position information of differences. As the fractional order p approach zero, the fractional difference correlation peak became to the difference of two images; as the fractional order p approach one the result is the same as the result of difference correlation.

The GaN thin films were grown on Si(111) substrate by Mg-doping simultaneously using a pulsed laser two-beam deposition system. The characteristics of an undepoed GaN film and the Mg-doped GaN film were investigated by using X-ray diffraction, atomic force microscopy, room temperature Van der Pauw-Hall measurements and photoluminescence. It was found that the Mg-doped GaN films have the hexagonal wurtzite crystalline structures similar to the undoped GaN films. As increasing the doped Mg-doped dose, a decrease in the size of grains of the GaN films can be seen, and the GaN films become p-type conductivity. The optical property of Mg-doped GaN film can be improved with increasing p-type carrier concentration. But the p-type carrier concentration can be decrased and the crystalline quality of the GaN films can be degraded by the too high doping Mg dose. The intensity of the yellow band emission peaks become stronger with increasing the doping Mg dose. These results show that it is possible to obtain high p-type carrier concentration in GaN films using the optimal pulsed laser two-beam deposition parameters.

Though Bi, Al substituted Dy-iron garnet films for magneto-optical recording prepared by pyrolysis are nanocrystalline, but because the imhomogeneity of grain boundaries, the sizes of the grains are bigger and imhomogeneity, there is a serious problem of media noise in magneto-optical recording. While Bi, Al substituted Dy-iron garnet films for magneto-optical recording with Rb-doping not only decreased the crystallized temperature, but also decreased the grains sizes. The biggest grain size from 100 nm decreased to about 50 nm, average grains size decreased to about 30 nm, and the homogeneity of the grains was improved. The reflecting of the surface increased because of the doped Rb existed on the surface of the films in form of Rb2O condensate filling the surface curves. The signal to noise improved. So Rb-doping can greatly improved the magneto-optical characteristics of Dy-iron garnet films for magneto-optical recording.

In this paper, the absorption spectrum and the fluorescence (or emission) spectrum of the Nd 3+∶ Y 0.5Gd 0.5VO 4 crystal were measured; Its strong absorption wavelength is at 808 5 nm; Its π polarized absorption is stronger than its σ polarized absorption and their FWHM are 4 5 nm and 8 5 nm, respectively, their absorption cross section are 19 69×10 -20 cm 2 and 6 41×10 -20 cm 2, respectively; Fluorescence (or emission) spectrum FWHM at 1064 nm is 3 7 nm; Its fluorescence lifetime is 110 μs (Nd:0.8at.-%); These properties show that Nd3+:Y0.5Gd0.5VO4 crystal is a kind of potential efficient laser material.

Photoconductive effect and heat effect in semiconductor photoconductive detectors when they are irradiated by laser were considered simultaneously. A transportation model of photoconductive carriers and heat transmission model were established. The photoconductive carriers consistency and the heat equilibrium carriers consistency in PC-type HgCdTe detectors under various laser irradiation density were calculated. Instantaneous change behaviors of the detectors were imitated further. The imitative results arsults are identical with experimental results.

A novel LD-SPM interferometer, which can be used to measure micro-vibrations with a high accuracy in real time, is proposed. In this paper, a composite light source is employed to decrease the measurement errors caused by the light-intensity changes. Experiments verify the usefulness of the interferometer.

The saw blade often cracks, breaks up or vibrates during sawing steel. Aiming at solving this problem, laser quenching technology is adopted to treat the saw blade teeth instead of the general used heat treating method. because laser quench can make thinner quenched layer, finer crystal grain, higher hardness and better abrasion resistance, and the saw blade teeth can also maintain its good tenacity. When laser treating the saw blade teeth, by using metallography analysis, FEM simulation based on ANSYS, selecting appropriate laser processing parameters and strictly controlling the quenched area of the blade teech, the saw blades can be got with high abrasion resistance and high impingement resistance, consequently, which will reduce break-up, fracture or tip corrosion of the blade teeth. In addition, for the saw blade itself, besides the better sawing performance, its vibration and stability is still another problem which cannot be neglected. Laser hardening can change the stress distribution of the saw blade body, which is of significant influence on its vibration performance. If the technique is appropriate, which can improve its vibration property and ensure the sawing performance and decrease the noise. The effect of laser treating relies on the laser processing parameters, such as laser power and scanning velocity. Based on theoretical calculation and producing practies, by selecting appropriate laser processing parameters and the technique, the life-cycle of the saw blade can be prolonged and the sawing quality can be well guaranteed.

By using of the magnetohydrodynamic effect of electrical current, a new aspect of CO 2 laser beam welding of aluminum with an electrical current technique was reported. A DC power source was used to supply current to the weld pool. One pole of the source was connected with a tungsten electrode which was set in front of the weld pool and the other with the work piece in the rear of the weld pool. In so doing a closed electrical circuit was built. When the electrical current flows in the weld pool, a magnetic field is induced and electromagnetic forces are generated in it, which change the fluid flow and the heat exchange condition of the weld pool. So far the experimental results have shown that the weld depth and area increase and the weld seam becomes more slender when the current is up to a certain value, e.g. 200 A. In the experimental conditions, the weld depth increases maximum nearly by 32% and the weld area nearly by 20%, but the weld width decrease maximum nearly by 28%.

In laser assisted microprocessing, the temperature distribution in the small exposed region is the main parameter. The temperature distribution should not be influenced by the measurement. Therefore the remote sensing of the temperature distribution in the small exposed region is needed. So a computer-controlled temperature measurement system has been developed. The system can realize the real time temperature measurement of the small laser-exposed region nonintrusively. In the system, a InGaAs/InP photodiode converts the radiation from the small high temperature region into photocurrent. Then the photocurrent is amplified, and converted into digital data. Combining with calibration experiment, the computer calculates the temperature through interpolation. The system can reach a temperature resolution of 0.2 ℃. The measurement region diameter of 18 μm is also obtained. At the same time, algorithm has been designed to cooperate the move of the motorized stage and the acquisition of temperature data. It follow that the measruement of temperature distribution and the accurate location of the highest temperature region are realized.

The surface optical performances of K9 glass plate through different chemical cleaning procedures were synthetically characterized by p-polarized reflectance method, atomic force microscopy and laser damage test. The results show that the extinction coefficient of glass surface with acid erosion decreases clearly, and its fineness and laser-induced damage threshold increase accordingly. Further the glass surface optical performances can be improved through alkaline cleaning. In addition, with the development of cleaning program of glass plate, the changing trend of glass surface optical parameters measured by p-polarized reflectance, accord with that of observed surface roughness and damage threshold.

In this paper, the fatigue specimens with center hole and metallography specimens made by sheet of 1420 Al-Li alloy were processed by intense pulse laser, then the surface of laser shock processed zone was observed by SEM, and the fatigue test and hardness measurement were processed. Results showed that the surface of 1420 Al-Li alloy sheet was not destroyed by intense laser or shock waves, while laser shock processing could improve the hardness and fatigue properties obviously, and strengthened zone was similar to the laser spot in size, and the hardened depth was up to about 1 mm.

The objective of this work was to determine the effect of low dosage CO 2 laser (825 mW/cm 2) on production of eggplants via radiating their dry seeds (10 s, 13 s and 15 s) and then analyzing plot yield. The result indicates that the longer radiated time was, the later the peak of increasing production appeared. The 13 s treatment was conductive to increment of yield of prophase and metaphase. But 15 s treatment can increase the yield of anaphase. The multi-regression, mathematical analogue was established on different treatment of plot yield accumulative value.

Systematic experiments on the effects of He-Ne laser irradiation combined with the traditional antitumor medicine of cyclophosphamide on peripheral blood serum IgG were conducted by using the experimental model of mouse S180 ascites sarcoma. Three groups of tumor bearing mice were irradiated upon the inner corners with the dosages of 11 00, 14 67 and 22 00 J/cm 2 He-Ne laser irradiation respectively, and injected with CYT intraperitoneally to observe the changes of peripheral blood serum IgG in tumor bearing mice. The values of peripheral blood serum IgG in tumor bearing mice in the mice with CYT+He-Ne laser irradiation treatment were higher than that with CYT treatment only. The kinetic detection of peripheral blood serum IgG indicated that CYT showed the immunosuppressive effects on the tumor bearing mice, and the immunosuppressive effects were alleviated in some degree by He-Ne laser irradiation.

He-Ne laser irradiation combined with salvia miltiorrhiza injection (SM) can treat ischemia and anoxemia well in clinic, but the mechanism remains obscure. In this paper, the effects of low intensity He-Ne laser irradiation, SM, and the combination of He-Ne laser irradiation and SM on the respiratory burst of bovine neutrophils were studied, respectively, which may help to understand the mechanism of the combination of He-Ne laser irradiation and SM fight against ischemic injury. The chemiluminescence was used to measure the respiratory burst of neutrophils. The results showed that 200 J/m2, 2000 J/m2 He-Ne laser irradiation can stimulate the respiratory burst of neutrophils, 40 J/2, 1000 J/m2, 6000 J/m2 He-Ne laser irradiation can inhibit the respiratory burst of neutrophils, 4～16 μL SM can inhibit the respiratory burst of neutrophils, and have the dose-effect relation. The inhibitory effect of the combination of 1000 J/m3 He-Ne laser irradiation and 8 μL SM is more marked than that of only laser or SM.

The generation of FWM going with PPLN-OPO was put forward for the first time. FWM frequency matching and quasi-phase matching conditions of bumping wave λ 3 (1064 nm), signal wave λ 1 (1500 nm) and idle wave λ 2 (3660.55 nm) in PPLN-OPO was discussed. The system of PPLN-OPO-FWM process was set up theoretically and the setting of optical system was realized experimentally. The conclusion of experiment was accorded with theoretical analysis, which is valuable for the study of PPLN, OPO and FWM in theory and practice.