In this paper, the performance of the diffractive optical element (DOE) for beam smoothing is analyzed by using the spatial frequency spectrum. Two parameters, light efficiency and top non uniformity, are re defined based on the spatial frequency spectrum. These two parameters can truly and exactly evaluate the performance of the DOE for beam smoothing, because their definitions go back to the origin. Finally, these two performance parameters are calculated, whether the precise design of the DOE for beam smoothing is adopted or not. The calculated results show the validity of the precision design of the DOE.

A new model of the "Needle" method that is more intuitionistic and physically more easily interpreted has been brought out, and the corresponding subject has been deduced particularly. The needed large incidence angle, high accuracy, non polarization anti reflection coating encountered in the process of development of laser gero has been designed successfully.

The positioning system based on surface plasmon resonance (SPR) can achieve nanometer resolution and repeatility. A special retroreflector is designed that incidence angle of its first reflection surface is equal to resonance angle of SPR. Then the surface is coated with gold film and a fibre probe is put behind the film to build up a SPR positioning system. The special retroreflector is component of SPR as well as the measurement mirror of interferometer to implement their integration. At the beginning of a measurement, a zero position is determined by SPR positioning system. If there is drift during measurement, reset interferometer data to diminish drift as soon as the special retroreflector reaches the zero position. The interferometer at nanometer positioning integration system is set up. Experiments show that uncertainty of interferometer is reduced from 70 nm to 10 nm. The measurement precision and stability of interferometer is increased.

The straight waveguide transmission characteristics of two dimensional photonic crystal are investigated based on the overall space theory of vector scattering. The relationship between transmission efficiency and waveguide length is calculated. The coupling of butterfly waveguide is discussed.

By treating photorefractive spatial soliton as rays in geometric optics, the action of the diffusion effect on propagation of PR spatial solitons is analyzed. Based on similarity between ray picture and classical mechanics picture, ray Hamiltonian equations of motion in a diffusion potential created by the induced change in the refractive index are resolved exactly by integrating. Results indicate that the center of the optical spatial solitons moves on a parabolic trajectory and the spatial frequency transverse component shifts linearly with propagation distance.

The killing experiment via photodynamic therapy (PDT) was carried on 30 Kunming mice inoculated with Louis lung cancer. The tumor suppressing rates and curves were observed between the experimental group and control group. Significant differences in the tumor growth curve (P<0.05), tumor mass and tumor volume existed between the two groups (P<0.01). The tumor suppressing rates of tumor volume and mass were 52.94% and 37.24%, respectively, in the experimental group. The results revealed selective injurious effect and growth suppressing effect of photodynamic therapy (PDT) on tumor cells, it is suggested that PDT can regulate the immune function for the mice inoculated with Louis lung cancer. Photodynamic therapy (PDT) will be a available therapy for malignant tumors.

Based on the characteristics of the FRTH in recording and reconstruction, a multiple fractional Fourier transform hologram (M FRTH) and its application in anti counterfeiting were proposed. The FRTH of several objects (or different parts of one object) with different transform order in different positions were respectively recorded on one holographic plate with simple fractional Fourier transform system conveniently. The multiple fractional Fourier transform hologram was fabricated and its characteristics in anti counterfeiting were discussed.

The holographic characteristics of a novel greenlight sensitive photopolymer with high diffraction efficiency and refractive index modulation are discussed. The influence of the exposure, recording intensity, intensity ratio of reference and object wave on the diffration efficiency are studied. The shortage to the high density recording of over exposure is displayed.

This paper studies the thickness of the free limiting layer in the laser shock processing. It analyses the relationship among the high intensity pressure caused by coating vaporization and explosion and transmitted into the interior of the metal layer and that of the free limiting layer, the adherent force between the free limiting layer and the coating, and the properties of the free limiting layer. On the above basis, the optimum thickness of the free limiting layer is obtained, which guarantees not only the optimum LSP effect but also the elimination of the free limiting layer at a time.

A new laser bending process of sheet metals with pre stresses is put forward. The different loading models are analyzed, and desired pre stress distribution in heated zone of the sheet is acquired. The three dimensional thermo mechanical model is established. Using the thermal elastic plastic finite element method (FEM), the process is simulated numerically. Its forming mechanism is analyzed. The bending angles of the sheet metals can be improved significantly, and the deformation direction can also be controlled easily by changing the direction and value of the pre load reasonably. The bending angles of the sheet metals augment remarkably with the improvement of the pre load, and both are in exponential relationship.

Laser clad metal ceramics layers of Ni based B 4C(NB 4C) and Ni based SiC(NSiC) have been obtained on 16Mn steel substrate by means of 5 kW continuous wave CO 2 laser. Microstructure, phases, microhardness and sliding wear characteristics of the layers have been studied. Microhardness and sliding wear characteristics of laser clad Ni based alloy layer (Ni60) was also investigated under the same conditions as a contrast. The results show that the microstructure of laser clad layers consists of dendritic solid solution and the fine eutectic structure between the dendrites. NB 4C clad layer mainly consists of γ Ni,γ (Ni,Fe), (Cr,Fe) 7C 3, CrB, Ni 3B, Fe 2B, Fe 23 (C,B) 6 and B 4C. NSiC clad layer mainly consists of γ Ni,γ (Fe,Ni), (Cr,Fe) 7C 3, Cr 23 C 6 and (Cr,Si) 3Ni 3Si. Microhardness and sliding wear resistance of the three laser clad layers have an order from high to low: NB 4C→NSiC→Ni60.

In this paper, a convex lens is inserted in the Z cavity, which is used to compensate for the thermal lens effect in gain medium. The experiments verify its feasibility. The maximum output power is 1.14 W, and the slope efficiency is 9 95%.

A novel erbium doped fiber ring laser utilizing amplified spontaneous emission (ASE) as a secondary pump source so that it can operate in L band stably was demonstrated. The output wavelength can be tuned in a wide range of 45 nm, from 1560 nm to 1605 nm, by changing the status of a polarization controller in the cavity. The relationship between the output power and the splitting ratio of the output coupler is also studied in this paper.

The bandwidth of three wave mixing optical parametric amplifiers has been investigated. The general mathematical models for evaluating parametric bandwidth and gain bandwidth of three wave mixing parametric amplifiers are developed via three wave noncollinear interactions, the models take into account crystal length, noncollinear angle, group velocity, group velocity dispersion and gain coefficient effects. The results show that the bandwidths are mostly limited by the group velocity mismatch between the signal and idler. Therefor, for any a three wave mixing parametric amplifier, the widest bandwidth can be obtained by choosing noncollinear angle, crystal length and pump intensity, and the super broad bandwidth gain can be realized.

Statistical characteristics of polarization mode dispersion (PMD) are investigated with dynamical equation. Simulations are performed in two methods: statistical ensemble and frequency ensemble. It is shown numerically that the results from the two methods are consistent with each other. Limited by the condition of long normalized distance, the square of rms delay grows linearly with normalized distance; the probability density functions (PDF) of PMD vector′s components obey Gauss distribution and the PDF of differential group delay (DGD) time obeys Maxwell distribution; PMD vectors are dispersed on the whole Poincare sphere.

By means of linear approximation method, the intensity correlation function and time dependent moments for the gain noise model of a single mode laser driven by exponential function correlation noise are derived. By using the computer technique, some novel phenomena are obtained. In certain cases, the time evolution curves of the intensity correlation function and time dependent moments exhibit two extreme values.

Properties of fanning effect and two wave coupling in a Ce∶KNSBN photorefractive fiber were studied. It is found that the fanning is weak when the incident angle is about 8°, which differs from that in a bulk crystal. Two wave coupling gain increases as the angle between pump beam and signal beam increases when the angle is less than 11°. It decreases as the angle increases when the angle is greater than 11°. The time evolution of transmitting signal beam at different angles was also given. The two wave coupling gain is 77 in the conditions that the angle is 8° and the signal to pump beam intensity ratio is 1∶1000, which is about 4 times that in a bulk crystal in the same conditions. The theoretical fitting and the experimental data are coincident quite well.

The radial velocity distribution and Doppler width distribution of Gd metal atomic vapor heated by the liner electronic gun is measured by the dye double laser induced fllorescence. With demarcating the velocity by isotope displacemen characteristic, the measuring device is simplifyed. The radial velocity and Doppler width distribution of belted atomic vapor are given. The radial velocity approximately linearly decreases with |β| angle increasing. The Doppler width approximately linearly increases with |β| angle increasing.

The numerical analyses have been conducted for characterizing femtosecond laser pulses with the spectral phase interferometry for direct electrical field reconstruction (SPIDER). The spectral phases and amplitudes of the typical femtosecond pulses were reconstructed, as well as the temporal intensity profiles and temporal phases of these pulses were retrieved. The numerical results are in accord with experimental observations.

Analytical expressions, basic rules and physical interpretation of transient phenomena in discrete fiber Raman amplifiers (FRAs) are presented in this paper, and agree well with simulation results. Characteristics of transience in gain clamped FRAs are also discussed based on these analytical expressions.

In order to acquire the largest extinction ratio (ER) of the converted signal in the cross gain modulation (XGM) wavelength conversion, the signal wavelength λ pk,s should be longer than the small signal gain peak wavelength of the semiconductor optical amplifier (SOA). The influence of the signal power, the signal ER, the probe power, the probe wavelength and the drive current of the SOA on λ pk,s  and the improvement of the ER is studied in detail by using the multisection model, and considering the nonsymmetry of the gain profile and the shift of the gain peak wavelength along with the carrier density. It is shown by numerical simulation that λ pk,s should shift to the longer wavelength about 7 nm when the signal power has a increment of 3 dB, while λ pk,s should shift to the shorter wavelength when the signal extinction ratio, the probe power and the drive current of the SOA is increased. The improvement of the ER is enlarged remarkably with the increment of the signal power and the SOA drive current, but decreases with the increase of the signal ER. The change of the probe power and the wavelength has little influence on the improvement of the ER.

An optical communication system with both EDFA and B DFRA is introduced. Two applications of B DFRA are studied. The first case is a receiver terminal with a receiver, an EDFA preamplifier and a B DFRA. The second case is a multistage point to point optical repeated system with both EDFA and B DFRA. The performance improvements in the two cases are calculated. The principle of the Raman pump power selection is discussed.