The Hall measurement equipment has been used to measure the mobility, the electron concentration and the resistivity of the 2DEG in the n-type modulation-doped GaAs/AlxGa1-xAs heterostruqture material before and during the sample being irradiated by FEL. Comparing the result of two cases, it is found that: 1) with enhancing temperature, the mobility decreases, and FEL makes the mobility increase; 2) the variety of the electron concentration with the temperature is more complex, but generally speaking, FEL makes electron concentration reduce; 3) with enhancing temperature, the resistivity increases, and FEL makes the resistivity decline, but the effect isn't obvious. These phenomena have all been analyzed in details.

In this paper, the coupling efficiency in the micro-prism sided-coupling method of double-cladding fiber was calculated and analyzed. The results show that this inclination of the pumping light to the incident facet of the micro-prism is the factor that affects the coupling efficiency mostly,the coupling efficiency can be larger than 90% in theory.

A method uniting the scalar approximation with the Snell's law and the Fresnel relations is presented in detail. Two formulae of the energy flux density and the diffraction efficiency are derived for the step transmission grating. As a example of application, the diffraction efficiency and the factors influencing on them are analyzed and calculated for the transmission grating with 4 steps. The results show that it is excellent for the gratings of d>4λ, because this kind of the method can not only avoid the complexity of the complete arrow wave theory, but also overcome the insufficiency of the pure scalar approximation. It isn't suitable for the gratings of d<4λ.

For improving the heterodyne efficiency in CO2 laser imaging radar system, a focus-off telescope is applied as beam broadening system to adjust the position of the local beam waist in local beam branch of the CO2 laser imaging radar optical system. By adjusting the local beam waist to the focal plane of the imaging objective lens the best phase matching situation is accomplished between the local beam and the signal beam reflected from the target.

In this paper, by using the hybrid algorithm merging hill-climbing with simulated annealing, the precise design of the diffractive optical element (DOE) for beam smoothing in fractional Fourier transform domain is completed. True beam smoothing has been obtained, the intensity distribution of any point, besides the used sampling point in the optimization, on the output plane is consistent with the demand for beam smoothing.

A technique of monitoring the change of blood perfusion utilizing the principle of laser speckle technique combined with CCD imaging method was studied. A laser speckle measurement system of measuring the velocities of blood flow in rat's mesentery was designed in present paper. The parameter and precision of the system was testified by a model experiment. On this basis, the dynamic changes of the velocities of the blood flow in rat's mesentery under different temperatures were measured. Meanwhile, the diameter of blood vessels was measured with CCD camera. With these measurements, changes of blood perfusion by heat were studied. The results indicated that this system and method could be used to monitor the change of blood perfusion effectively. This work provides a new method to measure thermal induced change in blood perfusion of tissue.

LCTV's phase modulation characteristics has been analyzed in this paper. Then a phase plate that can make a plane wave become a step-jump wavefront is inserted into a specific plane of incident light path of a cyclic radial shearing interferometer. And a gray distribution that can produce a conjugated wavefront of the step-jump wavefront was input the LCTV. The experimental result shows that the step-jump wavefront has been compensated ideally.

The very small aperture laser (VSAL) is a important light source used in the near-field optical storage system. So it is necessary for studying the near-field property of VSAL s output light. As the output region of the VSAL. the optical characters and the intensity distribution in the near-field of the metal film with micro-aperture have been numerical simulated using two dimension nonlinear FDTD (2D-NL-FDTD) method. Through analyzing the results from the viewpoint of the optics, the possible application in the near-field optical recording have been discussed, and some data indicating the near-field optical characters of the output light have been given.

In this paper, it has been studied that the hardened zones of ductile iron QT800-2 are processed through laser shock again, after laser quenched. The results indicate that properties of the zone treated through compound method is improved, compared to that through only laser quenched. The hardness increases by 18% and the wearability enhances about 100%. Especially, the residual stress of the interior of the material was changed into compressive stress.

Laser cladding of NiCrBSi-TiC composite coatings on Ti-6Al-4V alloy substrate was carried out, and the microstructure of the clad layer was characterized by SEM and TEM. The friction and wear properties of the clad layer were examined in atmosphere and in vacuum (10-5 Pa). The results showed that in the clad layer, the dispersive undissolved TiC particles and liquid-precipitated TiC were distributed in the matrix consisting of γ-Ni dendrites and γ-Ni+M23 (CB)6 eutectics, the liquid-precipitated TiC having a clear and smooth interface with matrix. The epitaxial growth of TiC was found at the interface of undissolved TiC particles with γ-Ni matrix. In atmosphere, the friction coefficients of the clad layer were ranged from 0. 3 to 0. 4, and the wear rate of clad layer was a magnitude lower than that of Ti-6Al-4V alloy. In vacuum, the friction coefficients of clad layer varied from 0. 4 to 0. 5, and the wear rate of clad layer was half as that of Ti-6Al-4V alloy.

Pulse laser with two-dimensional lattice distribution by optical transformation, was used to modify surface processing for ductile iron. The surface roughness of modified sample and original sample, modified layer depth, micro-hardness distribution and abrasion resistance were measured. On the condition of ensuring surface roughness (not melting or little melting) . the modified layer depth increased with pulse time. The wear resistance experiments showed that the wear resistance of ductile iron modified by pulse laser was increased by 1. 8 times.

This paper introduces a LD side-pumped CW Nd: YAG laser with the output of 37. 9 W in 1064 nm and the optical efficiency of 23.7%. The pumped system is analyzed by ray tracing. The disadvantage of experimental pump structure and the side-pumped laser design are discussed.

Using pre-pumping mechanism to improve the stability of passively Q-switched lasers, it has been verified with Nd3+ , Cr4+: YAG. Compared with CW pump and pulse pump, the stability of both frequency and amplitude for pre-pump is much improved. Finally, the experiment results of optimization of pre-pumping parameters are given.

This paper reported a continuous-wave Cr4+: YAG laser pumped by a Nd:YVO4 laser with a tuning range over 160 nm. At room temperature, the laser power is as much as 370 mW at an absorbed pump power of 5 W. The slope efficiency is 8. 7% with a pump threshold of 1. 94 W.

Theoretical analysis and calculations indicate that the gain of a semiconductor optical amplifier (SOA) will increase if reflectivity increases appropriately. By selecting appropriate refractive index and thickness of the antireflection film, the reflectivity of TM mode is larger than that of TE mode in a range of wavelength, such a reflectivity distribution can increase the gain of TM mode relatively, improve the polarization insensitivity of SOA and give SOA more flexibility in designing active region and waveguide to meet the requirements needed by other performances.

K9 glass substrates were cleaned by using a new cleaning technology, and some single-layer and multilayer coatings were prepared with the various oxide materials and different film thickness by the electron-beam evaporation technique. Comparison between the new cleaning technology and the ordinary cleaning was made in the experiments, and it were found that the new cleaning technology improved the surface roughness and the damage threshold of the new cleaning procedure showed twice as large as that of the ordinary cleaning procedure. Two methods of plasma spark and micrograph were used to detect the laser damage. Laser damage thresholds were obtained by using 1-on-1 test and R-on-1 test.

With the development of digital signal processing technology, digital spectrum LDA processor are very interesting. Owing to low ratio of signal to noise, limited burst continuance and wide dynamic measurement range in LDA systems, spectrum correcting methods have to be studied in order to improve the precision of LDA processor. Energy centrobaric, ratio, zoom FFT, phase difference and spectrum simulation correcting methods are used in LDA signal processing. Through carrying out simulating calculation with three kinds of Doppler signals, ratio correcting method is picked out and applied in real-time measurement, and the satisfying result is achieved.

According to thermal conduction theories of anisotropic materials that are irradiated with continuously modulated laser, a photothermal measuring method about the thermal conductivity tensor and the orientation of the principal axis of the conductivity of arbitrarily opaquely anisotropic materials is given based on the theories of So(3) group rotation.

This paper proposed a new method to measure the retardation of a wave plate, which is based on phase difference of reference signal and tested signal. This method is suitable for any wave plate and simplifies the measurement equipment.

To suppress Gordon-Haus effect, the narrow filter is inserted into optical communication system, as a result of compensating for the filter loss, the excess linear gain amplifies linear waves coexistent with soliton trains. leading to instability of the background. If light intensity is strong enough, in fiber the nonlinear gain will be engendered, by use of the effect, it is not necessary to compensate for the filter loss. This paper have studied the optical soliton stable propagation in the fiber communication system with nonlinear gain circumstance in the case of introducing the soliton potential function in the theory aspect.

As the key component in the WDM network, the acousto-optic tunable filter (AOTF) is broadly used in the field of optical communications and optical interconnections. But an obstacle in its application is its frequency draft along with the change of the temperature. In this paper, the temperature property of the AOTF has been analyzed theoretically. The calculation shows the temperature draft of 0.8 nm/℃. Additionally, a set of PID temperature control system is fabricated, to successfully stabilize the temperature of the AOTF within ±0. 1℃. The temperature property of AOTF is also measured by the PID system. The results agreed with the theoretical analysis very well.