The misalignment errors of Hartmann-Shack (H-S) wavefront sensor and deformable mirror in adaptive optics system and Common Path/Common Mode adaptive optics system are studied, by using the directly wavefront slope method and the voltage-surface characteristic of deformable mirror. In the adaptive optics system, re-measurement of the deformable mirror′s response functions would decrease the effects of adjustment error and the system has large tolerance; while in the Common Path/Common Mode adaptive optics system, adjustment errors would have different effects on the compensation performance of the system, because different data fusion method is used. Modified slope fusion method and voltage fusion method have taken the difference of the matching relationships of two H-S sensors and deformable mirror into consideration, so the effects of adjustment errors are the same with those of the normal adaptive optics system. The systems have large tolerance too. Higher precision of adjustment is required when the diretly slope fusion method is used because it is base on the assumption that the relationships at two H-S sensors and deformable mirror are completely identical. The numerical results are given in the course of analyzing.

In this paper, the compensation effects of Hartmann sub-aperture gradients in an adaptive optics (AO) system were analyzed. A kind of optimal-gradient reconstruction algorithm was deduced from normal least-square (LS) reconstruction algorithm by considering the statistical characteristics of disturbed wavefront and measurement noise. The optimal-gradient reconstruction algorithm is concise and effective in practice. The compensation effect and the stability were calculated in the condition of atmospheric turbulence.

A fiber Bragg grating is bonded on special material with a negative thermal expansion coefficient. The simple and compact temperature compensation fiber Bragg grating package is demonstrated. The total variation in wavelength over temperature range from -20～44 ℃ is 0.08 nm, which 1/8 of the uncompensated fiber Bragg grating.

The interactions between two femtosecond dark solitons are numerically investigated. The results show that femtosecond dark solitons are less affected than bright solitons by their respective interaction forces. The latter attracts each other and collides into one pulse, then they keep the state of repulsion without periodicity. The former repulses all the way and the repulsive forces are weaker than those of bright solitons. They have no periodicity,either. In addition,the numerical simulation results show that the interactions between femtosecond dark solitons are the same as those of picosecond dark solitons. It is found that their interactions agree with the empirical expression of picosecond dark solitons for the separation of two solitons as a function of initial separation and traveling distance. And the smaller the initial separation between two dark solitons is, the larger the difference between numerical simulation results and formula calculation results is.

The spectral broaden characteristics of three supercontinuum (SC) fibers with different dispersion properties are compared. Then parameters of standard dispersion shifted fiber (DSF) are optimized from aspects of pulse compression and spectrum reshaping demands respectively to generate broadband and flattened SC spectrum. At the same time, principles of parameter optimization in DSF design are also proposed.

The co-effects of the polarization mode dispersion (PMD), group velocily dispersion (GVD) and self-phase modulation (SPM) in high bit-rate transmission systems are studied. Both in time domain and frequency domain, the pulse evolutions are analyzed. It is proposed that chirp, GVD and SPM can be used to compensate PMD in certain conditions, for example, in the positive dispersion fiber (β 20) or adjusting the input power, both can compensate PMD. The simulation results demonstrate that there exists the optimized input power to minimize the system penalty (in our simulation model that is 10 dBm). The optimization strategy would be helpful to the design of the 40 Gbit/s optical transmission system.

An average method is applied to the nonlinear diffusion equation to obtain nonlinear analytical models for the index profiles of two-step ion-exchange splitters. In this way, the models obtained can predict the index profile after two-step exchanging from the first surface index profile (initial condition), which makes a fine curve with Gaussian function.

Theoretic design of Er 3+-Yb 3+ co-doped phosphate glass (LGS-L) waveguide amplifier was performed by a rate-equation formalism with overlapping integral method. Numerical results demonstrate that, for the Er 3+-Yb 3+ co-doped phosphate glass (LGS-L) fabricated by authors with an Er 3+ concentration of 1.51×10 26 ion/m3 and a Yb 3+ concentration of 19.1×10 26 ions/m3, a gain of 2.6 dB/cm can be obtained, and more than 15 dB gain at an Er 3+ concentration of 2.0×10 26 ions/m3 for amplifier length of 4 cm is possible. Furthermore, effects of the overlapping between lateral distribution of optical fields(signal and pump) and that of Er 3+(Yb 3+) co-doped on gain and optimum length and effects of the ratio of Yb 3+ to Er 3+ doped on gain at a pumping wavelength of 980 nm are discussed.

Based on the condition of paraxial approximation, the simple relational expression among the beam parameters, such as the mode field half width, far field divergence half angle and beam propagation factor M2, in the diffracted field of dielectric planar waveguide TE 0 mode is presented. The beam parameters can be calculated accurately by the mode field distribution of the waveguide, or by the diffraction frequency spectrum distribution in far field which is measurable exactly in the experiment. The calculational formulas of M2 factor are described by the ratio of mode field half widths defined by second moment and differential operator in near field, or the the ratio of far field divergence half angles defined by second moment and differential operator. Finally, the analytic function and scope of the beam parameters in the diffracted field of the dielectric planar waveguide TE 0 mode are demonstrated.

The impact of multipath interference (MPI) on the noise figure of fiber Raman amplifier is studied. The noise figure is analytically expressed in terms of the Raman gain and the Rayleigh scattering parameters of the Raman fiber. The difference between the power spectral characteristics of the multipath interference noise and that of the Raman spontaneous emission noise is considered. It is demonstrateed that the MPI can be a significant degrading factor to the noise figure when the Raman on-off gain and the input signal power are increased. A modified noise figure measuring method is proposed so that the noise figure accounts for the MPI deriving from the sum of Rayleigh backscattering signal components.

The dynamic characteristics of semiconductor optical amplifiers (SOA) and the performance of switching window of terahertz optical asymmetric demultiplexers (TOAD) are investigated numerically by taking into account not only interband effects but also intraband effects, such as carrier heating, spectral hole burning, two-photon absorption, and ultrafast nonlinear refraction. Two cases are considered. 1) change the frequency of signal pulse while let the wavelength of control pulse unchanged. 2) change the frequency of control and signal pulse on the condition that the frequency of control pulse is the same as that of signal pulse. Numerical results show that in order to obtain flat and narrow switching window, the wavelength of control and signal pulse should be the same, and the difference between the wavelength of control pulse and the center wavelength of SOA's gain spectral should be little larger.

In the method of iterative shift-and-add for astronomical image reconstruction, a key problem is to determine whether the developing direction and the convergence result of the iterative process are correct. According to the properties that an object bispectrum corrsponds to the image of the object in speckle masking method, the object bispectrum is adopted as the standard function to test the iterative results. The method of least-square is used to distinguish the developing direction and convergence result of the iterative process, so that the blind action of the iterative process can be avoided and a correct reconstructed image will be got.

A method of amplitude fitting is proposed to solve the degeneration problem of the quality of binary images reconstructed by kinoforms. By fitting a small amplitude to the zero-amplitude area of the binary image, involvement of phase in this area during the iteration is ensured. As a result, the degree of freedom during the design of kinoform is increased, and the quality of the binary image reconstructed is improved. Quantitative analyses and discussions of the improved result are given by comparing the final simulation results.

A new method is developed to merge two spatially registered images with differing focus points based on multi-resolution wavelet decomposition and evolutionary strategy. At first, the wavelet decomposition without down-sampling is used to perform an adding of wavelet decomposition components of each image. Then, in terms of differences of area-based energy feature in two original images, evolutionary strategy is adopted to divide the region and perform the fusion. The experimental results show that the proposed method can achieve better fusion performance than wavelet transform method.

A novel self-mixing interferometry (SMI) with dual external cavities was proposed. The model of interference, as well as the modulation and demodulation of interference signal are analyzed. The developed technique uses an additional reference reflector to form dual external cavities between the LD and the target, and reference external cavity is used to compensate the phase error due to optical frequency fluctuation. FFT phase detection technique was applied to analyze SMI signal. By using these techniques, the high precision measurement can be obtained. It is a promising technique used in microelectromechanical systems (MEMS), optical engineering and other engineering application.

By variational approach, the characteristic of Z-scan in thick media with high order nonlinearity is theoretically analyzed. In comparison with the result of Z-scan only considering the third-order nonlinearity. It is found out that the fifth-order nonlinearity can not be neglected when the media has large fifth-order nonlineartiy or the intensity of laser is more powerful. These results are useful in searching high performance optical nonlinear materials and designing optical limiter.

The two-photon absorption properties of 4,4′-bis (dimethylamino) stilbene synthesized recently are calculated at ab initio level. The hybrid density functional theory is embraced to optimize the geometry of the molecule and the time-dependent density functional theory is used to study the nonlinear optical properties of the molecule. Simulation of the solvent effects is carried out by the self-consistent reaction field theory with the polarizable continuum model. The numerical results show that three-state model is good enough to give the two-photon absorption cross section for the lowest excited states, which is consistent with experimental measurement quite well. As the increase of the polarity of solvent, the wavelength of single photon is red-shifted and the two-photon absorption cross section is increased slightly. The TPA cross sections agree well with the experimental data.

The fundamental conception about visual range of low light level (LLL) imaging system is described. Based on the common apparent distance detecting equation, a more practicable and reliable detecting equation is established by using the factors, such as atmospheric transmissivity, spectral matching factor, etc. The relations of parameters, which have an influence on performances of system, are analyzed. The visual range of the night vision goggle under the specific circumstance is estimated which proves the revised apparent distance detecting equation is effective and the design of the system is feasible. Some approaches to improve the LLL imager′s performance are presented.

Based on the characteristics of tip-tilt mirror, a new method of flat field processing for solar images using tip-tilt mirror is proposed. The principle and the procedure for this method are introduced. The experimental results are presented. The results show that it is very effective to do flat field processing for solar images with tip-tilt mirror. After making flat field correction, the quality of the solar images can be improved.

Light-emitting diodes based on heterojunction with structure ITO/PDDOPV/PPQ/Al have been successfully fabricated, in which PDDOPV {poly (2,5-bis (dodecyloxy)-phenylenevinylene]} is a hole transporting polymer while PPQ } is a hole transporting polymer while PPQ [poly (phenyl quinoxaline)] is an electron transporting polymer. Light emission was observed under both positive and negative bias voltage. Light emission under positive bias voltage mainly is originated from PDDOPV, but light emission under negative bias voltage includes blue light emission which is from PPQ and yellow emission which is from PDDOPV. Intensity ratio of the blue emission to yellow emission increases with increasing negative bias, when the reverse applied voltage is 22 V, 24 V, 26 V, 28 V, respectively, the ratio of PPQ peak value to PDDOPV peak value, IPPQ/IPDDOPV are 1.092, 1.329, 1.605, 2.046 respectively. In other words, the emitting color is voltage-dependent color tunable, which is a promising property to realize colorful display. The light emitting mechanism under negative bias voltage is analyzed.

Starting from the propagation law of partially coherent light, spectral changes in Young′s two-slit experiment with Schell model beams are studied. That the spectral switches in Young′s experiment at far zone can also take place is pointed out. The spectral switch effect, which is physically attributed to the diffraction by the slits and spatial coherence of light, increases with increasing slit parameter ε and source spatial correlation Δ. Detailed numerical results are given to illustrate the behavior of spectral shifts and spectral switches in Young′s experiment and a comparison with previous work is also made.

The first rainbow of multilayer spheres is studied, whose profiles of the refractive index are exponential decrease or increase by using generalized Lorentz-Mie theory of multilayer sphere. The results obtained demonstrate that the angle positions of the rainbow of the multilayer sphere is sensitive to the refractive index profile, whether the refractive index exponential decrease or exponential increase. The results are very useful to probe the refractive index, its gradients and temperature of the combustible particle.

In this paper, based on the reciprocity theorem, the light scattering from a spherical particle above a slightly rough dielectric surface is studied. According to the electric field integral equation of the surface, the recursive solution for the induced current on the slight rough surface is derived using the perturbation expansion of the surface, and the method for computing the interaction field is given. With considering the known scattering matrix of the slightly rough surface and the spherical particle, the analytical solution of the scattering cross section for the composite model is presented, the backscattering cross sections are calculated and discussed in detail.

A reproducible color gamut in CIE L*a*b* 3D color space is proposed as a performance index for evaluating the reproducibility of dichroic filters used in color separation/recombination system. Using this method, the effect of broad conic angle incidence on the color reproducibility from the special angle characteristic of dichroic filters is analyzed. And from the viewpoint of optimizing the volume of the color gamut, a precompensation method is presented to optimize the filters′ design parameter so that the color reproducibility of the films will be promoted remarkably when the incident beam is broad conic angle beam.

The influence of niobium (Nb) doping on the properties of lead tungstate crystals (PWO) has been investigated. Transmission, emission, positron annihilation lifetime spectrum and X-ray photoelectron spectra(XPS)of PWO∶Nb and undoped PWO were reported. The luminescence characteristics of the Nb-doped PWO crystal was discussed by comparing the results with that of pure PWO crystal. Nb doping improved the luminescence property of PWO and enhanced the percentage of its quick component. The defects in PWO crystal caused by Nb dopant has been studied by means of positron annihilation lifetime spectrum and X-ray photoelectron spectra. The results show that Nb dopant increases the concentration of lead vacancy (V Pb) as well as the concentration of low-valent oxygen. The Nb 5+ will occupy the lattice of W 5+ and make some (WO 4) 2- change to (NbO 3+V O)-, which will result in the improvement of luminescence performance of PWO crystal.

In this paper, a hybrid integrated micro fiber spectrometer is put forward. A holographic concave grating is adopted as dispersing and imaging element, which can easily realize the flat spectrum plane. The detecting element is linear CMOS image sensor. The spectrum range of this micro spectrometer is from 400 nm to 800 nm. The whole system has many advantages, such as a few optic elements, higher transfer efficiency, compact structure and small volume. The structure and parameter of this micro spectrometer are optimized. First xxperiment and computer simulation are carried out to test the design. The results has been showen that this micro fiber spectrometer has a good performance.