The refractive index fluctuation of atmosphere are mainly caused by variations in temperature and humidity. A new method of studying effects of humidity fluctuation on the structure parameter of the refractive index is proposed. Humidity fluctuations is obtained from fluctuations of ‘sonic temperature’, very closely equivalent to virtual temperature ,using a three-component sonic anemometer. The structure parameters C2Q, CTQ, can be calculated. C2n and temperature fluctuation, humidity fluctuation are measured by a sonic anemometer and microthermal probe both in dry desert and in damp sea shore. Meanwhile, the humidity fluctuation can be estimated by a mode using field experiment meteorologic condition as input parementers. Both measurement and mode show that humidity directly influencing C2n can be ignored. Humidity effects is mainly achiered associating with temperatime fluctuation. Generally, the contribution to C2n is less than 10% except near a marine surface or saturated soil especially during occurrence minimal C2n before sunset.

Evanescent-field coupling based on long-period fiber grating (LPG) and bi-conical tapered fiber is proposed and investigated both theoretically and experimentally. The light coupled to the cladding modes by LPG can be transferred to a bi-conical fiber. In order to obtain high coupling efficiency, the phase-matched condition should be satisfied and the two fibers should be close enough. The characteristics of the coupling also depend on the position of the coupling region. To get higher coupling efficiency, the coupling region should locate after LPG. This kind of evanescent-field coupling can be used to monitor the characteristics of the LPG which is used in the devices or systems on line.

A novel numerical model and an efficient algorithm are developed to calculate the powers of signal and noise light waves in multiple wavelengths bidirectionally pumping fiber Raman amplifiers. The relationship between the noises, including the amplified spontaneous emission noise and the double Rayleigh backscattering noise, and the degree of pumping directionality is studied. According to the simulation results there exists an optimal degree of pumping directionality, at which the total noise power drops to its lowest value. Furthermore, an optimization of evaluating factor considering both the optical signal to noise ratio and nonlinear distortion impact is put forward. After optimization, fiber Raman amplifiers can achieve not only flat gain spectrum but also the best balance between optical signal to noise ratio and nonlinear distortion impact.

The supercell model for the Bragg fibers is proposed for investigating the mode characteristics and propagation properties. The transverse refractive index profile is expressed by Fourier series, and the energy band structure is obtained by the plane wave expansion method. The mode propagation constant and the expansion coefficients of the electric field can be obtained from the eigen system which is deduced from the full-vectorial coupling wave equations based on the localized orthogonal Hermite-Gaussian functions. The supercell mode is implemented when the high-index core Bragg fiber is taken into account. Some lower-order modes are analyzed, and the mode birefringence of the fundamental pairs can be used to scale the accuracy of this algorithm. The supercell model is also efficient for the hollow core Bragg fibers.

The crosstalk of cascaded stimulated Brillouin scattering (SBS) in the S band distributed fiber Raman amplifier forward pumped by the fiber laser has been studied. By S band distributed fiber Raman amplifier using narrow spectral bandwidth (<100 MHz) as signal source, the forward stimulated Brillouin scattering was observed when amplified signal power is larger than the threshold of SBS, which is the phenomena that transmitting sound wave Brillouin scattering is amplified in fiber amplifier. Second-order SBS in the Stokes region appeared with the increase of pump power, and the power of even order SBS was stronger than that of odd order Brillouin-Rayleigh scattering in the experiment. The forward cascaded multiple stimulated Brillouin emerged when the pump power is increased further, and the amplified signal power is translated into SBS with stronger noise when the gain decreased. The crosstalk of SBS damaged the performance of Raman amplifier and made Raman amplifier useless in DWDM fiber transmission system, therefore the signal power and pump power entering fiber had to be controlled strictly. In the experiment, the signal and companion lines beside SBS could be observed, too.

Optical switch is a kind of important passive optical components in all-optical communication network. A kind of optical structure design method of 4×4 free-space optical switch is presented and a matrix theoretical analysis is made for this 4×4 optical switch structure. The 4×4 optical switch has a novel optical module configuration. It consists of polarization beam splitter, 1/4 wave plate, 1/2 wave plate, polarization optical modulator, right angle prism, and total reflection mirror. The operation is independent of the polarization states of input optical signals. Non-blocking optical switching can be implemented between input channels and output channels. This new kind of optical switch structure has the features of less optical components, compact size, modularity, polarization-independent. The routing control table for the 4×4 optical switch is given based on the matrix analysis. It provides a theoretical analysis method to describe routing controlling states between any one of the input channel and any one of the output channel of the 4×4 optical switch. So the routing controlling function of the non-blocked optical switching matrix can be realized expediently.

The model of stimulated Brillouin scattering in fiber grating based Fabry-Perot resonator is studied. The analytical solution of steady state stimulated Brillouin scattering equations for the first-order Stokes wave is given, and its transmission power and reflection power are calculated. The analytical solution of pump wave at incident end and the equation of energy conservation with neglecting fiber attenuation are obtained. Numerical solution for second-order Stokes wave is then given using Shooting and Levenberg-Marguardt (L-M) methods under the boundary conditions. The dependence of the transmission power and reflection power of pump wave and Stokes wave on incident wave power is investigated. Furthermore, the distribution of the power of pump wave and Stokes wave in the Fabry-Perot resonator is simulated and discussed.

A new algorithm is presented to extract colored texture by effectively merging the texture feature, color feature and spatial correlation of color texture based on wavelet decomposition. Experiments are conducted on a set of 20 natural colored texture images in which multiple feature fusion and classification can be performed on the basis of the pyramid wavelet decomposition (PWD), incomplete tree-structured wavelet decomposition (ICTSWD) and wavelet packet decomposition (WPD). It is demonstrated that correct class rate of multiple feature fusion based on PWD is 85.78% and correct class rate based on WPD is 91.03% with the dimensionality increased exponentially, but the dimensionality of feature fusion based on ICTSWD descended greatly because of selective decomposition in sub-band, and correct class rate is 90.63% after fusion, simultaneously, multiple feature fusion based on ICTSWD has better anti-noise ability than fusion using WPD.

Modulation measurement profilometry (MMP), which encode the height information into the modulation information of sinusoidal grating on the measuring surface, is a vertical measurement technique. It is suitbed for measuring those objects with discontinuous height steps and/or spatially isolated surfaces. The application of MMP based on Fourier-transform is discussed in measuring complex surface, with presenting the concept of the depth-of-modulation and anlyzing its influence on measurement. Based on the depth-of-modulation, the detailed method and projects of designing measurement system are proposed to improve accuracy of measurement, and several practical questions influencing accuracy and solutions are discussed. The measured results show that the MMP based on Fourier transform measuring surface of complex objects can improve the accuracy of measurement greatly.

A new device of lateral-spread photorefractive volume holographic lens is presented. It is recorded holographically by the interference of a plane wave and a spherical wave in a double-doped LiNbO3 crystal. The lens can laterally spread and focus the plane wave which perpendicularly incident crystal planar, and vice versa. The lens has the advantages of light weight, high reliability that the general volume holographic lens possesses. Moreover, it has the particular properties of lateral-spread, small duty ratio and easy of minimized integration. On the basis of the coupled-wave theory of local volume holography, the amplitude distribution and the diffraction efficiency of the diffracted beams are calculated. The normalized intensity profile at the focal plane is given and compared with that of an ideal convergent spherical wave.

An approach for compression of hyper-spectral images based on wavelet trellis-coded quantization is proposed. Processing of spectral and spatial redundancy make up the main ingredients of compression of hyper-spectral image. Firstly, the proposed algorithm takes advantage of spectral difference pulse code modulation (DPCM) to remove the spectral redundancy, then the discrete wavelet transform is carried out over the error images resulted from DPCM and trellis-coded quantization with uniform threshold value is adopted to quantize the sub-band images. At last, entropy encoding of quantized code-words is performed by adaptive arithmetic encoding. To compute optimal quantization thresholds in rate-distortion sense for each sub-band of all spectral bands, an algorithm for bit allocation based on sub-band statistic characteristic and R-D characteristic of trellis-coded quantization is also desigued. In the experiments, excellent performance of the proposed algorithm is demonstrated. For the hyper-spectral image of experiment, the PSNR of the algorithm is 37.1 dB at the compression ratio of 32. This shows that the approach can efficiently compress hyper-spectral image and be suitable for the applications of hyper-spectral images compression.

In the experiment of 10.6 μm continuous wave CO2 laser induced diffusion, the substrate is irradiated by a focused laser beam. To realize selective diffusion in local region, the diameter of the laser beam spot on the surface of the semiconductor substrate is only about dozens of microns. Because temperature rise of the exposed region must meet the requirement of diffusion experiment, high power density of the incident laser beam is necessary. On the other hand, the 10.6 μm light absorption coefficient of semiconductors such as Si, InP increases with the rising of temperature. The above two factors can easily lead to a thermal runaway phenomenon. The mechanism of thermal runaway was analyzed, then a numerical method was proposed to calculate the relation between the temperature of the exposed region and the power density of the incident laser beam. When the semiconductor substrate is kept at room temperature before the laser irradiation, it is shown that the temperature of the exposed region cannot be induced steadily to the value required in the diffusion experiment by using irradiation of laser beam with constant power. This problem can be avoided by preheating the substrate and real-time controlling the temperature of the exposed region.

Laser-induced plasma shock wave and cavitation bubble by pulsed laser ablation of a metal in water are investigated by a high-sensitive optical beam deflection technique. The experimental results present the laser-produced plasma shock waves propagation, the detachment of the shock wave from bubble wall, cavitation bubble oscillation and bubble-collapse-induced shock waves generation in the vicinity of a solid boundary. It is shown that with the increase of the number of oscillating cycles, the maximum and minimum bubble radii are decreased sharply, as well as the corresponding oscillating durations. The minimum bubble radius is determined by the bubble energy and gas-vapor content in a cavity. The duration of bubble expansion is obviously longer than that of contraction during the same oscillating cycle.

Firstly, the short-term stability of the laser's frequency stabilized is theoretically studied by methods of third and fifth harmonic, and the experiment of increasing the frequency short-term stability is performed. Secondly, the semiconductor laser's frequency stabilized circuit system is discussed, and by useing this system to take the rubidium 87's hyperfine spectra F=2?kF'=3, 1 as reference frequency, that laser's frequency is stabilized by the third harmonic sign and fifth harmonic sign of saturated absorption spectra of 87Rb. The laser used is DL100 of TuiOptics, center wavelength is 780 nm, linewidth is 1 MHz, and finally a frequency stabilization got is 10-12. We computed the short-term stability generated by these two stablization technology theoretically is computed, and the calculated result with the experimental result is compared, and they were similar to each other.

A new type of laser resonator with annular output beam is presented. Annular output beam is obtained by outer ring coupling in a stable laser resonator. The integral equation of this type of laser resonator is resolved by using Fox-Li numerical iteration method. Amplitude distributions and phase distributions of fundamental mode of the diffraction-coupling output field and the fields on the surfaces of the mirrors are computed by computer programming when the output plane mirror's radius varies in a plane-concave stable resonator. The theoretical results predict that there exists steady diffraction output field with annular beam distribution when the output plane mirror's radius is less than that of the fundamental mode in an usual stable resonator. Experimental TEA CO2 laser with printed circuit board preionization is used. The laser has gain length of 90 cm. The resonator is composed of a total-reflective concave spherical mirror of curvature radius 20 m and a total-reflective plane mirror of mirror radius 4.5 mm, separated by 5 m distance. The annular output spot of fundamental mode with inner radius 4.5 mm and outer radius 5.5 mm is obtained by the experiment. Therefore the feasibility of the scheme generating annular beam has been verified theoretically and experimentally.

A new pumping structure of laser gain media slab is proposed, the thermal wavefront distortion caused by the non-uniform temperature distribution of the laser gain media slab will be self-corrected in this structure, and the theoretical model of the transient temperature distribution is established to describe the pumping structure, the analytic expression of the transient temperature distribution of the laser gain media slab is derived from heat conduction equations. Numerical simulations of the temperature distribution within 10 seconds and at 60 seconds are given for N-31 Nd

How to decrease the threshold and how to improve the quality of output beam of stimulated Brillouin scattering (SBS) phase-conjugation cavity is a problem. The output characteristic of compound phase-conjugate cavity with good beam mode is reported. The output energy of single pulse is 13.35 mJ with 15 ns of widths, and the divergence angle is 0.6 mrad. The results of pulse widths and output energies and beam profiles are given, indicating that using the compound cavity is a useful and easy method to improve the quality of beam mode.

Based on the theoretical analysis of cascading of sum frequency-generation and difference-frequency-generation processes [χ(2)∶χ(2)] under quasi-phase-matching conditions, periodically poled lithium niobate (PPLN) and annealed-proton-exchanged waveguide (APE) were fabricated. Using the fabricated crystal of PPLN-APE, an all-optical switching experiment is carried out. The control pulse is generated by a Q-switched Co2+-doped MgAl2O4 laser with a wavelength of 1.54 μm. The CW signal beam is generated by a laser diode with wavelength of 1.5 μm. When the control pulse intensity reached 3 kW and the CW signal intensity reached 1 mW, the all-optical switching realized a switching efficiency of 13%. In the conclusion, the key technologies to improve the switching properties further is discussed.

For space optical remote sensor (SORS) with either film or TDI-CCD imaging, to achieve higher resolution requires more accurate real-time image motion compensation. This primarily depends on real-time computation of the image motion velocity vector (IMVV) and error budget and synthesis on related parameters. An effective modeling scheme is introduced and the derivation of IMVV equation, error budget and synthesis by Monte-Carlo method are presented in detail. This total solution was applied to SORS system field test and has been confirmed to be very accurate based on the resolution, transfer function at Nyquist frequency, signal-to-noise ratio and average gray scale of the captured images.

A new idea of linked Voigt anomalous dispersion optical filter (VADOF) is prenserted. Its transmission spectrum is analyzed and calculated. The result shows that, compared with VADOF, the linked VADOF changes the multi-peak configuration of VADOF into single-peak one and has narrower bandwidth and higher noise rejection ratio. The linked VADOF is applied into a new laser frequency-locking scheme, which improves the stability of laser frequency. Consequently, a novel inter-satellite laser link system using linked VADOF for frequency locking in the transmitter and Faraday anomalous dispersion optical (FADOF) for radiation rejection in the receiver is given. The result of field test demonstrates that this novel system is feasible.

Because some visible hybrid diffractive-refractive optical systems were complicated, the optical and thermal properties of glass materials in visible band were various. The initial system configurations of the visible hybrid optics could not be reliably gained by achromatic and athermal equations like those of the infrared hybrid optics. The thermal property of diffractive optical elements was analyzed, and achromatic design and athermal design were separately carried through in the optical system design, prompting the completion of designing visible-band, athermal camera lens for space applications. The image quality with the systems was uniform and the shifting range of MTF was confined within 6%, at 20～100 ℃. Design result showed that hybrid optical system had compact structure and reliable performance within required temperature range.

Slow light propagation in solid state material is initially observed at room temperature. The slowdown of light resulting from dramatic change of refractive index by spectra hole which is produced by coherent population oscillation is investigated in a ruby crystal at 514.5 nm from Ar+ laser. Measured delay is about (2.314±0.005) ms, corresponding to group velocity as low as (43.215±0.094) m/s. The variation of the delay and the group velocity with modulation frequencies is observed in the experiment.

The angular spectrum theory is introduced to analyze optical diffraction lithography in thick film photoresist, and the reflection and transmission on the interface and the variation of dielectric coefficient in depth direction in thick film inhomogeneous resist are considered. A novel lithography model is put forward to simplify the analysis of optical diffraction, and the fast Fourier transform (FFT) algorithm is converted into convolution calculation to save computation cost. Numerical calculation results show that the reflection and transmission on the interface and the variation of dielectric coefficient in depth direction have important effects on the diffractive field intensity of thick film resist.

For analyzing the energy loss of an extraordinary beam at crystal surfaces, a simple method is proposed to calculate the corresponding reflectivity and transmissivity. According to the boundary relations of the electromagnetic field, and based on the phenomena of double refraction and double reflection in crystals, the reflectivity and transmissivity are deduced at boundary when an extraordinary beam is incident from an isotropic medium upon a crystal or from a crystal to an isotropic medium with optical axis in the incident plane. The change of the direction of the optic axis has influence on the critical angle θc but little influence on reflectivity, The reflectivity for e-beam incident upon a crystal from an isotropic medium is experimentally verified with LiNbO3 crystal. The formulate given in this paper are general and representative.