The AlGaInAs semiconductor saturable absorber grown by Metal-organic Chemical Vapor Deposition is used as the saturable absorber in a 808 nm LD-pumped passively Q-switched Nd∶YVO4 laser at 1.06 μm.The dependences of the pulse energy,pulse width,pulse repetition rate on the pumping power are measured.With an incident pump power of 10.57 W,an average output power of 3.4 W is obtained,and the corresponding slope efficiency is 39%.At this pump power,the repetition rate reaches the maximum value of 101 kHz.The Q-switched pulse width reaches the minimum of 1.76 ns with an incident pump power of 8.07 W.Using the rate equations of passively Q-switched lasers,the theoretical results for the pulse energy,pulse width,pulse repetition rate are obtained,which show an agreement with the experimental results on the whole.

Based on the master oscillator power amplifier(MOPA) system including a single mode erbium-doped fiber laser used as the master oscillator,and a large-mode-area Erbium/Ytterbium double-clad fiber used as the amplifier gain medium,the polarization states of the seeding laser and the amplified laser are experimentally investigated.The results show that the polarization degree of the output laser of the amplifier is very low without any polarization control device;after inserting a polarizer in the loop of the signal source,the degree of polarization is improved evidently and the stability of the polarization state becomes better,both for continuous wave operation and for mode-locked operations.The mode-locked operation has a little lower polarization degree and a better stability than the continuous wave operation of the amplifier.When a polarizer introduced in the loop of the signal,the instability of the polarization state of the output of amplifier is mainly caused by the polarization parameter azimuth.As a result,the combination use of a polarizer and a polarization controller is supposed to improve the polarization degree and the stability of the output of the amplifier,furthermore,polarization-maintaining gain fiber is recommended to be used to avoid the random perturbation of the environment.The work offers an important experimental basis for the control of the polarization state in the laser beam coherent combination.

A coupled-mode theory for treating the coupling of two terahertz (THz) wire waveguides was studied using the coupled-mode assumption.Both coupling equations and coupling coefficients were obtained by using approximations equivalent with those in coupled-mode theory of optical waveguides.Furthermore,the solutions and coupling characteristics of coupled-mode equations for two same wire waveguides were obtained.The present theory is useful for treating problems involving energy exchange between the wire waveguides.

A wide bandwidth low crosstalk triplexer is designed and fabricated using silica arrayed waveguide gratings(AWGs).In order to obtain wide bandwidth for all three wavelengths whose wavelength differences are large，multimode interferences(MMIs)with different structures are used at the junction between output waveguides and Rowland circle.Using two-dimensional finite difference beam propagation method，the simulated results show that 3 dB bandwidth of the designed triplexer are up to 23 nm,23.5 nm and 25 nm for 1 310 nm,1 490 nm and 1 550 nm，respectively.The insertion losses all are 4 dB.The crosstalk is less than -40 dB for 1 310 nm，and are less than -40 dB for 1 490 nm and 1 550 nm.Using broadband light source，the measured results show that 3dB bandwidth for 1 550 nm is 23 nm.Using three independent narrowband light sources，the measured results show that the insertion losses of the three waves all are 7 dB.The crosstalk is less than -40 dB for 1 310 nm，and are less than -39 dB for 1490 nm and 1 550 nm.The measured and simulated results are basically consistent.

Nonlinear refractive index(n2),absorption coefficient(β) are material figures of merit for ultrafast all-optical switch.n2 and β of GeS2-Ga2S3-Sb2S3-AgCl glass were measured by using Z-scan technique .The result shows GeS2-Ga2S3-Sb2S3-AgCl glass is characteristic with high value n2(1.581×10-10esu),little β at 800 nm(β=4.707cm/GW).The nonlinearity is attributed to high polarization of cation in the glass.

Based on Valley′s quasi-cw approximation,the writing and erasing of gratings in materials exhibiting bulk photovoltaic effect on illumination with short light pulses (such as ns pulses) is investigated.The expression of space-charge field is given out in the paper with two time constants τpa and τpb.When considering and not considering the photovoltaic effect,the diagrams of the two time constants as a function of irradiance in units of 1/(sτR) are the same.The energy required to erase a grating to 1/e of its initial value is also studied in the two cases and the two results are also the same.In the case of short light pulses irradiance,photovoltaic effect has no effect on the writing and erasing photorefractive gratings in the LiNbO3 crystal.

The polarization states of the diffraction beams of nearly perfect conducting blazed gratings in Littrow mounting are studied by numerical simulation.A FDTD program is written,the electromagnetic fields for various polarized incident beams are calculated,and the polarization states of the diffractive waves are extracted.The relation between the polarization state of the diffraction wave and the grating balzed angle and polarization angle for the linearly polarized incident wave is analyzed.In the spectral range of 1 530 ~ 1 570 nm,the polarization dispersion is studied for the linearly and circularly polarized incident beam.The most important conclusions may be significative for the engineering design.

We have discussed the proper gimbal point position in conformal optical system based on the pupil astigmatism criteria.Then,we derive the best position of the aberration correction gimbal point by using aberration correction criteria in rotationally symmetrical system.The result proves the application potential of the aberration correction criteria in conformal optical system design and the dome's image quality has been improved greatly by properly choosing the position of the gimbal point.

In order to improve thepositioning accuracy of mapping system,a design on optical lens of transmission semi-telecentric beam path in image space is expounded,and assembly method based on DFT(Design For Test) of single lens suit and whole optical lens are expounded.The results show that the proposed MTF of optical lens is 0.45(@77 lp/mm), the ground resolution power is 5m,and the distortion is 3/10 000.The test results indicate that each parameter can satisfy user′s qualification.

To overcome the disadvantage of low radiation power for photoconductive antenna,three types of antennas,including dipole,bow-tie and spiral antennas,are studied,where finite integration technology are used to compute their radiation impedances.The simulation results show that the impedance of dipole antenna is dependent on the dipole length,width,photoconductive gap and the width of transmission line,and has a peak value in resonant frequency,so the dipole antenna is suitable for applications working at specific terahertz frequency.The bow-tie and spiral antennas,known as broadband antennas,have approximately stable impedance over the terahertz frequency range under study.The simulation results also show that,the interdigitated fingers,which can be modelled as an additional capacitance,cause the antenna impedance to fall dramatically at high frequency.

An in-fiber Mach-Zehnder interferometer filter based on a pair of long-period fiber gratings (LPGs) had been operated in the reflection mode by incorporating a broadband chirped-fiber Bragg grating (CFBG) or an optical fiber mirror reflector.As a result,the extinction ratio has been nearly doubled and,by tuning chirp rate,i.e.reflection bandwidth of the CFBG using a beam-bending method,channel number of the formed optical comb filter can be easily changed.In our experiment,two comb filters with channel numbers being changed among odd ones from 1 to 5 and 3 to 9 have been achieved,respectively.Even channel filtering can also be achieved if the center wavelength of the chirped fiber grating is changable.

An optimized method of dynamic matched grating filtering demodulation system is proposed and experimentally validated,in which PZT′s hysteresis effect is eliminated by use of rising sawtooth wave and inverse function of relationship between PZT′s voltage and displacement is adopted as the sawtooth wave to correct the PZT′s nonlinear effect.Furthermore,a reference fiber Bragg grating is introduced to realized temperature compensation,of which the center wavelength keeps invariable.In the rising stage of the sawtooth wave,the matched grating will match with the reference grating and the sensing grating at different time.The time difference depends on the center wavelength of the sensing grating,and is insensitive to the temperature of the demodulation system.The experimental results indicate that linearity is improved by 2%,the sensitivity error is less than 0.6% of the theoretical result.The relative error caused by temperature changing from 10℃ to 60℃ is less than 1%.

Study the optical fiber′s UV transmission performance,utilize the depressed inner clad design,with different doping content of Ge and F in fiber′s core,use the Plasma Chemical Vapor Deposition process to develop the sample fiber,and adopt the same drawing process control to fabricate the fiber sample.Through contrast the samples′ optical characters,attenuation sprctrum and UV transmission efficiency and stability,get the influence of the fiber′s UV transmission performance by the doping content.With the increase of the Ge and F doping content the fiber′s 305 nm laser transmission efficiency would decrease obviously.The UV laser transmission efficiency changed from 99.3%~97.8%.This would be caused by the increase of the defects content in the fiber′s core,and then it would decrease the UV laser transmission efficiency.However,with the increase of the Ge doping content,the fiber′s UV transmission stability would increase from 904%~97.2%.The results indicate that:the fiber′s UV transmission efficiency was directly influenced by the Ge doping process,then the transmission stability was influenced by the other doping element,the new defects have been generated.

A kind of all-glass polarization maintaining PCF is designed and fabricated using rod-in-tube method and capillary-stacking technique.The microscopic end profile of the fiber exhibits an excellent maintenance in the fine structure of the PCF.Thus,this design has effectively overcome the defect of air-holes collapse in traditional PCF fabrication process.Measurement of the fiber attenuation with the cutback method is 6.84 dB/m at 1 550 nm.The polarization measurement indicates that the fiber has a good capability to maintain polarization.Therefore it is feasible to achieve the fiber that can effectively maintain polarization and is easy to be fabricated by this all-glass design.

The omnidirectional total reflectors based on one-dimensional dielectric and magnetic photonic crystals were investigated in this paper.The transmission matrix method was adopted to analyze the transmission properties of such reflectors.In order to obtain broad omnidirectional total reflection bandwidth,the decimal Genetic algorithm was used to optimize their structural parameters including the thickness ratios of the layers and the numbers of periods.The calculation results show that,with the more parameters(including the number of periods and the thickness ratios of the layers) participating in the optimization,the omnidirectional total reflection band becomes wider,the number of the layers becomes less,and the total thickness of the whole structure becomes thinner.Finally,an optimal design described as(0.255A0.255B)5(0.169A0.066B)8 is obtained.The omnidirectional total reflection bandwidth can reach to 1.34ω0,the number of the layers is just 26,and the whole thickness is just 1.8634λ0.The whole structure is very simple.

The indispensable information regarding the image reconstruction is derived immediately/para-immediately by the optical synthetic aperture imaging with the immediate/para-immediate u-v coverage with the samples taking from the space frequency domain.The image of the observed object is obtained.The advantages of the immediate/para-immediate observation using the optical synthetic aperture imaging technology with the immediate/para-immediate u-v coverage are introduced.The analysis of imaging for LBT is proceeded as an example.It deduces the point-spread function and optical transfer function of the LBT system based on the algorithm of the Fast Fourier Transform (FFT),convolution and deconvolution.It also discusses the global transform function and its influence on the effect of imaging.It explains the imaging properties of the immediate/para-immediate u-v coverage.With the means of the experimental simulation,it tests and verifies that the global transform function could restore the image of celestial body under the circumstance which fits the condition of the imaging of the para-immediate u-v coverage.

With CW (continuous wave) laser and a high-speed CCD,hologram of alcohol spray is recorded based on digital in-line holography arrangement.The reconstruction images of a hologram of the particle field are handled the way that in-focus images of the particles in the volume are integrated into a plane and binarized and the edge of the particle images is extracted by Roberts,then Hough transform and sub-pixel precision computing completed,and the size and position of the particles are obtained.The displacement of the particle is extracted by two sequences of the hologram recorded by two exposures and the velocity of the particle is obtained,and the experimental results are given.The research results show that the proposed experimental system is applied to measuring internal combustion engine spray field,which is simple in optical structure and low in cost.

The practicability of reconstructing the kinoform with white-light is discussed.It is drawn that the kinoform can be reconstructed with white-light,if a slit is placed between the kinoform and observer(called as rainbow kinoform).And a method for making rainbow kinoform is proposed.The computer-generated rainbow hologram is calculated.A finite impulse response(FIR) low-pass filter with real coefficients is designed according to the band-width of the object.The FIR band-pass filter with complex coefficient is gained by moving the spectrum of low-pass filter to the position where the spectrum of object is located.And the zero-order and conjugate image is eliminated by filtering the rainbow hologram with designed filter in spatial domain.The kinoform of 3D scenes is made by extracting the object phase distribution of the filtered hologram.In the exprements,the clear reconstructed image of rainbow kinoform is observed under white-light illumination.It is proved that the proposed approach is feasible.

Two models of the image restoration for sparse aperture optical systems are proposed.The adapted condition is analysed about Wiener filtering,least squares filtering and MLE blind deconvolution.According to the experiment,the issue points out Wiener filtering and least squares filtering use camara lens′ OTF as the whole system MTF.In theory the Wiener filtering can make the best image restoration.Considering sparse aperture optical systems with noises,the blind deconvolution uses the atmosphere transfer function and the lens′ OTF as the system MTF to have a image restoration.The result is better than Wiener filtering using constant K and least squares filtering.

The preceding typical atmosphere of Beijing Olymplc Game were measured and analyzed in combine with Raman Lidar,Tapered Element Oscillating Microbalance (TEOM),Black Carbon (BC) and Visibility analyzer from July 19 to July 28 in 2008.The vertical profile and spatio-temporal distribution of aerosol extinction coefficient was shown,and the ratio of aerosol extinction and backscatter was calculated.The relationship of visibility,PM10,PM2.5,BC and aerosol extinction coefficient was analyzed with the data of visibility and mass concentration of particle matter at atmospheric haze.The result shows that there has direct correlation of visibility,mass concentration of particle matter and aerosol extinction coefficient.The technique and method can be provided for controlling the composite pollution of atmosphere based on data comparison,complementary and enrichment of different instrument,and the scientific basic and reference can be provided for treatment of urban air pollution.

A compact Mie scattering lidar system at a wavelength of 532 nm is developed to measure the optical properties of atmospheric aerosol particles and horizontal visibility.Some observations are performed and analyzed.The Fernald method is employed to retrieve the extinction coefficient of aerosol.Some continuous continual experiments are carried out for verifying the feasibility of the Mie scattering lidar at Xi′an area,and the observation results are demonstrated here by measuring the aerosol profiles of the extinction coefficient,the spatial temporal variation of atmospheric boundary layer height which are obtained within whole day at one hour interval,and the horizontal visibility which agrees with the data obtained from the local weather bureau.The observation results show that the Mie scattering lidar is capable of measuring efficiently the optical properties of atmospheric aerosol particles and horizontal visibility.

Fluorogermanate glasses with the compositions of 65GeO2-12AlF3-10BaF2-8Li2O-5La2O3 codoped with Tm3+ and Ho3+ ions are fabricated by conventional melting method.According to the Judd-Ofelt theory,the J-O strength parameters(Ω2，Ω4，Ω6)of Ho3+ are calculated,by which the radiative transition probabilities,fluorescence branching ratios and radiative lifetimes are obtained.According to McCumber theory,the absorption and emission cross-sections corresponding to the 3H6→3F4 transition of Tm3+ and the 5I8→5I7 transition of Ho3+(at 2.0 μm)are obtained,and respective gain cross section spectra are computed as a function of population inversion.With 808 nm LD excitation,the cross-relaxation process of Tm3+ and infrared emission spectra of Tm3+ sensitized Ho3+ ions are studied.The results indicate that the energy transfer efficiency of Tm3+(3F4)→Ho3+(5I7)ions is enhanced and the infrared fluorescence intensity at ~2.0 μm is increased as the Ho3+ co-doped into glass.

ZnO thin films are deposited on sapphire (0001) substrates by a high-purity ZnO target and a pulsed Nd:YAG laser with a wavelength of 355 nm.The structural,optical and electrical properties of ZnO thin films are grown and investigated in various substrate temperatures.The morphological propertie of the films is analyzed by atomic force microscopy (AFM).The optical properties and electrical properties of the films are investigated by Raman scattering and ultraviolet photoluminescence (PL) emission and FTIR Hall-effect measurements,respectively.The results of the temperature of the substrate is a highly important parameter to influence the film morphology and films grown,and the high quality crystallinity has an excellent UV emission at 500 ℃.

Bianisotropic split ring resonator (SRR) metamaterials under TEM waves are analyzed,which reveal that imaginary wave number leads to the SRR resonance.The field distribution over SRRs is expanded into Floquet modes.The metamaterial resonance is engendered by the evanescent modes.The resonance behavior happens in the transmitted modes with the same polarization as the wave incident in the main plane.And the electric and the magnetic resonances are varied with different incidence angle.

A new improved method based on active controlling of phase-shifting is proposed.Five frames of sinusoidal gratings with exactly the same known phase-shifting value are programmed actively.While the five gratings are projected to the measured object one by one,five frames of distorted fringes are captured by CCD camera synchronously.If the known phase-shifting value substitute for the phase-shifting value calculated from distorted fringes in Stoilov′s algorithm,the accuracy of the 3D profile reconstruction may be improved obviously.The experiments show that the average absolute error is less than 0.07,and the mean square error is less than 0.07.

Based on analysis of laser interference length measurement principle,optical path offset model and length of optical path in cube-corner prism model are given,and a simple expression of influence relationship of misalignment error and positioning error is derived with neglecting of straightness errors and angle errors.Positioning errors measurement experiments are carried out and a quantitative estimation method for misalignment error is given.

In order to measure and correct a distorted image,a vertical Ronchi carrier-fringe pattern is used as measuring template,and a distorted grating pattern is captured by the imaging system.Fourier transform method is adopted to analyze the spectrum of the distorted fringe pattern,and the fundamental spectrum is extracted by filtering.An ideal image is obtained from the central region of the distorted image,where there is no distortion,and the unwrapped phase distribution and radial wrapped phase distribution are obtained by fringe analysis.The radial phase distribution is converted to the radial distortion distribution,and the corrected image is obtained utilizing the radial distortion distribution and bilinearity interpolation.The experiment results show that the method is valid.

A method of measuring 3D attitude of objects based on inclined angle of the lines between feature points is proposed,which is applicable to the condition that inter parameter is unknown and object is in a long distance.Synthetic images are applied to verify the correctness of the proposed method.As a result,the mean of absolute value of attitude error is less than 0.6°,and when the size of target are 350 pixels,the measuring error is less than 0.5°.The result shows that the proposed method is with highly correct and strongly convergent.

The Pancharatnam phase of a Tavis-Cummings model with the coherent state in Kerr medium is investigated theoretically and numerically. An exact expression of the Pancharatnam phase under this general system is obtained. The numerical results show that the dipole-dipole coupling strength between two atoms can change the quasi-period of the Pancharatnam phase evolution,and it is also proved that the Pancharatnam phase contains the information of atoms and the field. In the nonlinear interaction regime, the nonlinearity can cause the chaotic behavior of the Pancharatnam phase.

Using the Jaynes-Cummings model,the dynamical properties of the fidelity of quantum states in the system that consists of a two-level atom interacting with a single-mode field are studied.The frequency of the field varying with time in the form of sine is considered.The results obtained by numerical calculations show that the time-evolution behavior of the fidelities of field and system are not influenced by the frequency variation of field,but the time-evolution behavior of the fidelity of atom is modulated by the frequency variation of field.The larger the amplitude of the field frequency variance u is,the stronger modulation interaction of the field frequency variance is.When the amplitude u is larger than a fixed value,the time-evolution behavior of the fidelity of atom will display periodic oscillation behavior.Its oscillation period is in agreement with the period of frequency varying.

A new fuzzy fast Hough transform is proposed to detect the circular boundary of Labyrinth disc aperture in an aeroengine.In the new algorithm,the circle detection problem is decomposed into two stages consisting of a 2D Hough transform to find circle centre and a 1D Hough transform to determine the radius.The 2D Hough transform performs a hierarchical approximation to the solution,starting from a coarse description of the parameter space.The coarse-to-fine search technique is used to reduce the computing and storage requirements of the Hough transform.And,the fuzzy vote technique is adopted to lessen the uncertainty that arise from edge pixel position error and gradient direction error.The circular contour detection results by the proposed algorithm are compared with the results by Standard Hough Transform and Randomized Hough Transform respectively.The experimental results show that the fuzzy fast Hough transform can detect the contour quickly and accurately.

An image coding algorithm based on binary wavelet transform (BWT) and modified SPIHT was proposed.With the BWT,it eliminates spatial correlation and achieves compact representation of an image with integer precision,by mapping image pixels from real field to real field.Modified approach also presented to improve the poor visual quality of the traditional SPIHT algorithm.In our method,BWT coefficients are reordered according to their perceptual importance.The visually important coefficients are transmitted as early as possible,whereas those compression distortions are distributed in less visual significant regions.In this way,the visual qualities of decoded images are significantly improved without impairing the rate-distortion performance of the encoder.Experimental results show that the proposed algorithm achieves optimal compression performance and visual quality for images with various characteristics,as compared with other popular compression algorithms.

The global searching method is adopted in the traditional correlation algorithms in target tracking system, resulting in the large amounts of calculation, the difficulty of real-time implementation and even the loss of the tracking target when the target is partially shaded or in sharp attitude variation. To solve the problems, an improved approach based on the loop correlation template matching and Kalman filter is proposed to realize target tracking. Kalman filter, to make the tracking more active, estimates the possible region of the target in the next frame at first,and finds the best matching points by the loop correlation matching in the aforementioned region while the loop-template matching overcomes the loss of the horizontal matching points caused by the sharp attitude variation. So the algorithm has strong robustness, and is of translation and rotation invariance. In the experiments, the proposed algorithm is applied to the tracking of a main battle tank partially shaded and a jet with “Viktor Pugachev′s Cobra”. Compared with the traditional algorithms, the algorithm herein can steadily track the targets in less time without losing them.

A new rotation invariant feature extraction method for texture classification is proposed.2-D Fourier transform is applied on a texture image,a disk area within the central region of image is chosen,and frequency is sampled on the selected area with equal interval angles within the orientation［0°,180°］,so orientation decomposition is realized.A set of complex Morlet wavelet are applied on projection slice of each direction to decompose each projection into several frequency channels,the average and variance extracted are computed in each frequency channel,and then linear regression model is employed to computer realationship feature between frequency channels.1-D DFT is applied to features and the amplitudes of Fourier coefficient are selected as features,then the extracted features are rotation invariant.Experimental results show that features extracted have a good rotation invariant and better classification performance with some existing methods,and better classification results can also be achieved for non-rotation texture classification.

According to the visible and infrared image sequences,when tracking in every frame,color features of visible image ,vertical projective image and horizontal projective image features of infrared image are extracted.The weight in each channel was calculated with Bhattacharyya coefficient,and the weighted mean-shift tracking algorithm in dual-channel videos was derived.So visible/infrared dual-channel target tracking algorithm based on weighted mean-shift was proposed to improve tracking performance while luminance of object is changed.The proposed algorithm can effectively use the better information of each channel,for it makes the channel whose Bhattacharyya coefficient is higher have higher weight.The experiment in object tracking demonstrates that the proposed algorithm overall performance outperforms one channel(visible or infrared) target tracking algorithm based on mean-shift，and it almost remains the tracking performance when luminance of object is changed.

A SHC confidence based on 3SS of digital video stabilizing method is proposed.The 3SS is used to compute the motion parameter between the standard frame and the current frames,and the SHC confidence is applied to restrict the result of 3SS,aiming at the improvement of motion parameter accuracy.The method is proved to be effective and workable on a320×240 in-vehicle motion video with ±40pixels fluttering.

The accuracy of iris recognition is lowered due to the shelter by part of eyelid and eyelash during the process of iris detection.A noise detection method using the 2D-Gabor filter is proposed for it.Firstly,the eyelid and eyelash are detected using 2D-Gabor filter in the normalized iris images.Then the noise regions are marked.Finally,the interferential bits in the iris codes are eliminated to avoid the noise effect to the recognition as much as possible.The experiments by using the CASIA(3.0)database are finished.The result shows that the recognition rate with the noise detection is 99.02%,but the recognition rate without the noise detection is 98.46%.

Aiming at the tracking question that one target changes to multi-targets,such as the separating of airplane and rocket,the separating of airplane and missile and the separating of classes,a complex target- identify arithmetic is put forward.It is based on target′s area,length,width,length and width ratio,compat degree,moment of inertia and flight path.This arithmetic can identify the target exactly.Among the arithmetic,a new primary and secondary objects switch technique are applied.The arithmetic heightens the multi-targets track reliability.The results show that the arithmetic is provided with high targets identify precision,good targets switch stability and high extend apply value.

The checkerboard-shape filter pair with directions 45° and 135° which can decompose the input image into two images containing different directional information of the original image are designed.A 2-D separable CMFB is applied to the two images to realize subband decompositions.This cascading structure corresponds to a new directional filter bank of redundant ratios of 2.The new DFB can provide good directional and frequency selectivity.The new DFB and the doubly local Wiener filtering algorithm are combined to develop a new image denoising algorithm.The experimental results show that the proposed algorithm achieves satisfactory performance improvement for images with abundant textures.