A kind of flat box-like resonator for reactor-pumped lasers (RPL) is presented here, which has a zigzag propagation inside and high coupling efficiency with the reactor. Under the condition of uniform energy loading in the cavity, several factors of laser design and parameters relating energy deposition are explored in this paper. A method for optimizing output coupling is reported as well. These will benefit future experimental work.

In designing the kW order TEM00 mode continuous wave laser unit, a quasi-sealed-off and multi-folded resonator that has the good transverse mode selection ability was developed. In order to insure the mode volume matches with the discharge volume well, the negative thennal lensing effect was taken into account, resulting in the stable output laser whose power is high enough. Based on the forgoing design, a mechanical chopper Q-switched CO: pulse laser was developed then. The resonator parameters were adjusted, including the calculation of the positive thermal lensing effect of the high power laser windows. At last, a Q-switched CO2 laser pulse with the highest average output power of 800 and TEMoo mode was obtained.

An one-dimensional deep sub-wavelength grating is studied. A new method is developed for this sub-wavelength gratings fabrication. In this method, the grating periods are composed of multilayer films which are obtained by the method of PECVD. The diffractive efficiency of the grating is computed by using rigorous coupled-wave analysis (RCWA). The property of polarization of the grating is also discussed.

In this paper, the field distribution of focal plane of the phased-array waveguide grating (AWG) multi/ demultiplexer is analysied by using impulse response function. The numerical solution shows that crosstalk is related to the array aperture and the waveguide width. The method is simple and feasible.

The reflection characteristic of a fiber loop mirror, which comprises two pieces of polarization maintaining fiber, is studied in theory and experiment. A flexible method based on the polarization maintaining fiber loop mirror is proposed for the gain flattening of an erbium-doped fiber amplifier. The excursion of the ASE intensity of the flattened-EDFA is 2 dB in the 1527-1562 nm wavelength region.

The basic principle and the sensing structure of a novel torsion sensor are proposed in this paper. The theoretical formulas of torsional angle sensing are derived and the torsional angle of this sensor is linear to the power loss of the multi-mode fiber. In the range of the torsional angle between - 40°and +40°, the torsion sensing has been realized technologically with the sensitivities 0.375 dB/degree for the symmetrically bidirectional linear torsion sensing and 0.592 dB/degree for the bidirectional unsymmetrical linear torsion sensing.

The output characteristic of reflective fiber optic displacement sensor was analyzed. A novel reflective fiber optic sensor for displacement measurement over a wide measuring range was designed. An inverse model of the sensor was obtained based on neural network trained by the sensor's output and the actual sensed displacement. The neural network was used to process the sensor's output signal, which could largely widen the measuring range and enhance the measuring accuracy.

Based on non-radiation transitions of heavily doped ions in the crystal fiber, a laser-pumped fiber-optic thermal tip has been developed for laser thermotherapy. Pumping by a 809 nm laser diode, the thermal tip generates a maximum temperature of 465° in air (with pumping power of 1124 mW) and 98° in egg white (with pumping power of 933 mW), which is high enough for laser thermotherapy. Meanwhile, the thermal tip shows satisfactory results in temperature stability, thermal response time, bio-compatibility, thermal impact resistibility, and chemical stability.

Using the self-convergent beam width method, the beam width propagation and beam-propagation parameters of hard-edge diffracted super-Gaussian beams are studied. It is found that the self-convergent beam width of super-Gaussian beams obeys the same law as that of the beam width based on the second-order moments without truncation, when the self-convergent-width factor satisfies a certain condition. Therefore, the beam propagation factor (M2-factor) obtained by using this method is invariable upon propagation. Meanwhile, a detailed comparison between the self-convergent beam width method and the asymptotic approach is made and the equivalence between the two methods is discussed. In addition, a concise physical meaning of the self-convergent beam width method is given.

The result shows that the wheat seedling has partly ability of excision repair, and the time of repair peak is about from four to six hours after the UV-B radiation. By excision repair pathway, the repair for the removal of damage induced by UV-B radiation from cellular DNA of the wheat can be influenced by He-Ne laser irradiation. The ability of excision repair of the wheat can be enhanced by He-Ne laser irradiation, and the excision effect of the He-Ne laser irradiation is obviously at the excision peak (at five hours) . The peak of DNA repair synthesis was from six to seven hours after treated by He-Ne laser and UV-B irradiation.

In this paper, an algorithm which process the single image of CO2 laser imaging radar is presented. The simple quick algorithm consists of median threshold filter and homomorphic mean filter. The speckle index by the algorithm is 0.1489. Meanwhile, a few of the filter results are compared, for example median filter, mean filter, median threshold filter and homomorphic mean filter etc.

The recording structure of reflective rainbow hologram on a spherical surface is different from the structure on a plane. In this paper, the relation between objects and reflective diffraction images of spherical surface is derived by calculating phase functions on spherical surface. The design method of recording structure of rainbow hologram of spherical surface is proposed, and the experiments are given.

The effect that the intensity of the writing spot relating to the amounts of defocus in the laser direct writing photolithography is analyzed based on the diffractive theory 'and the ray-tracing method, respectively. The photolithographic experiments with various amounts of defocus are developed by using four-axis laser direct writing system, which agree closely with the results of the theory or the ray-tracing method. The grating and reticle fabricated by this way are measured with atomic force microscope (AFM).

A thin surface layer always exists near the surface of laser heating melt pool due to the fluid flow driven by the surface tension gradient. In order to simulate accurately the fluid flow in the laser heating melt pool, the influence of the thin surface layer must be considered carefully. In this paper, the computational domain is divided into two regions, region I includes most part of the melt pool except for the thin surface layer on the top of the melt pool, i.e. region II . Comparison of simulated results using the two-region method with those using single-region method shows that one still can employ the single-region modeling approach to obtain correct isotherms and flow fields provided the mesh near the upper boundary is fine enough to resolve the surface layer.

By analyzing the effects of a Brewster plate inserted a KTP intra-cavity frequency-doubling green laser, by using multi-Brewster plates or combining a Brewster plate with a Q-switch, a high power single frequency green laser stable output is achieved. When incident pump power is 1.3 W, CW SLM green laser with average power of 124 mW and Q-switched SLM green laser with peak power of 108 W are obtained, respectively.

The two cascaded Raman fiber laser using fiber Bragg gratings as cavity mirrors was theoretically simulated and analyzed by use of the double pass configuration. The effects of fiber length, excess loss and output reflectivity on the output characteristics of two cascaded Raman fiber laser, such as output power, slope efficiency, and threshold power were studied on basis of numerical simulations, and the optimized parameters were given.

In this paper, the Yb-doped fiber amplifier (YDFA) and its amplifying characters are reported. In order to study the characters of the YDFA, a narrow linewidth laser was used as the input signal, which produced by the single frequency DPL or narrow wavelength-width LD, operated in CW mode (DC signal) and pulse modulated mode (AC signal). The gain more than 26 dB with the fiber only eighteen meters was obtained.

The divergence of Stokes output versus power density of pump in the Brillouin amplifier was experimentally studied and the relations of divergence among Stokes output, Stokes seed and pump were also experimentally studied. The change of pump power density hardly affects the divergence of Stokes output, and high quality Stokes output could be obtained by controlling the divergence of Stokes seed beam.

Damage mechanism of shells with inner pressure that are exposed to high power CW CO2 laser is studied here. The physics model and numerical solution model of thermal and mechanical responding is described. The finite element method is used to simulate nonlinear temperature and stress profile. Two types of shells are considered and the laser power density is varied from 400 W/cm2 to 1500 W/cm2. The damage times are presented and the damage areas are plotted.

The High quality InGaAsP materials, which wavelength shift is more than 177.5 nm with a small mask width of 0-40 μm, have been obtained by use of NSAG-MOCVD in the low growth pressure of 130 mbar. The composition variation, strain and the enhancement ratios of the vapor phase concentrations for TMIn and TMGa on the epilayer surface at the center of the mask opening to that in the maskless region with the mask width have been deduced, respectively. It is discovered that the ratio variation with the mask width is dependent on the concenration of TMIn and TMGa in the vapour phase when the mask width is less than the threshold mask width, and independent on that when the mask width is more than the threshold mask width. Moreover, the phenomena of In rich with the mask width increase has been explained rationally.

A kind of 3-dimensional photonic band gap (PEG) material which is TiO2 matrix in strips shape is fabricated by using micromolding method. The periodic ridge strips, 10 μm in spacing, are composed of fee packed 200 nm-diameter air spheres, the cross-section of the strip is 10 μm wide and 600 ran in depth, which was observed by SEM measurement. Laser light was coupled into strips by optical fiber to characterize the optical properties of the PBG material. The observed optical band-gap structure is same as that of the PBG material obtained by conventional gravity-deposit-method. And so the above approach is a convenient, efficient way to fabricate PBG materials with patterns.

The photoinduced birefringence was investigated in an amorphous copolymer containing azobenzene groups. And the characteristics of writing and relaxation of photoinduced birefringence were analyzed. A new modified mechanism model of the photoinduced birefringence was established and simulated by computer. The minimums of the error between the experiment data and math's model were calculated by changing the parameters of the math's model, and the best parameter values were obtained thereby.

The characterization of photoinduced birefringence in a new kind of the azobenzerie doped polymer film was studied by varying the intensity of the exciting beam and the angle 9 between the direction of polarization of exciting beam and probe beam. The experimental results showed that the new polymer film has a good characterization for optical storage with the conditions of low exciting beam intensity. The qualitative explanation to the experimental phenomena was also given.