Based on the theory of generalized Huygens theory and the unified theory of coherence and polarization, distribution of the intensity of partially coherent radially polarized beams influenced by source wavelength, and degree of polarization (DOP) influenced by coherence, atmosphere turbulence intensity, spot size and source wavelength, are investigated while propagating in turbulent atmosphere. It is shown that while the partially coherent radially polarized beams propagate in turbulent atmosphere, the distribution of intensity is affected by source wavelength obviously. With the increase of propagation distance, the doughnut beam spot of the partially coherent radially polarized beam becomes a solid beam, which is related to source wavelength. The shorter the source wavelength is, the longer distance the partially coherent radially polarized beam propagates to form a solid beam shape. In addition, distribution of DOP is also affected by coherence, atmosphere turbulence intensity, spot size and source wavelength. At a certain propagation distance, the rate of DOP with radius increases with the larger original coherence, the weaker atmosphere turbulence intensity, the bigger spot size and the shorter source wavelength. Such tendency becomes more obvious with longer propagation distance.

Based on the extend Huygens-Fresnel principle,the analytical expressions for cross-spectral density matrix elements of random electromagnetic Sinh-Gaussian (ShG) beams as typical stochastic electromagnetic beams propagating through atmospheric turbulence are derived,and used to study change in the transverse degree of polarization of random electromagnetic ShG beams propagating in atmospheric turbulence.It is shown that distribution of transverse degree of polarization varies with location when random electromagnetic ShG is propagating in atmospheric turbulence.The smaller the structure constant C2 n ,the larger the Sh-part parameter Ω0 ,or the bigger the spatial correlation length σxy (σyx ) ,the longer the propagation distance of distribution of polarization into bimodal shape,flat shape,unimodal shape.

As one of most important simulation methods,hot air convection atmospheric turbulence simulator has been widely used in many area.However,there is rarely study on the spectral characteristics and probability density characteristics of the simulated turbulence.A long-term measurement is made in a real link under 1 km and 6 km atmospheric environment,and a simulate link by using the same laser emission device and measuring device.The detailed analysis of the spectral characteristics and the probability density fluctuations characteristics of the simulator are done.The experimental results show that compared with the real atmosphere,the spectral characteristics and the probability density fluctuations characteristics of scintillation generated by the convection atmospheric turbulence simulator are well agreed to the real atmosphere.For angle-of-arrival,the spectral characteristics and the probability density fluctuations characteristics are well agreed to the real atmosphere on y axis.But on x axis,because of the lack of crosswind,the spectral characteristics is different from real atmosphere.For probability density fluctuations characteristics,there is no obvious pattern.

Liquid crystal on silicon (LCoS) is a novel programmable diffraction optical element, which has been widely used in optical display, communication and storage etc. The diffraction of LCoS is analyzed and applied into 1 × N wavelength selective switch (WSS) as a wavelength selector, which has succeeded in switching the input wavelength to any output port. Based on the optical scale diffraction theory, the 1st diffraction distribution and efficiency of LCoS are discussed. The results show that the diffraction loss of LCoS is stable and lower than 5 dB when the grating phase order is greater than 10 pixels. Further, an LCoS-based 1 × N WSS is designed and the flexible modulation of channel space is realized. The WSS crosstalk is low and each output can be controlled independently. The total system loss is around 10 dB~14 dB.

According to the requirements of the sensing distance and signal detection for the Brillouin optical time domain reflectometry (BOTDR) sensing system, a hybrid G-Simplex coding technology is proposed based on Simplex code and Golay code. The BOTDR signal is processed by combining the G- Simplex coding with the average superposition algorithm. The results demonstrate that this method can keep the space resolution. The signal-to-noise ratio and sensing distance is improved by using a certain code length. Moreover, with the same denoising effect, the intensity of impulse response can be improved and the superposition times can be largely decreased, which reduce the difficulty of weak signal detection.

When a coherent beam transmits by a multimode fiber,speckles will appear in the output field.Vibrating the fiber is approved to be an effective way to suppress the speckles.To reveal the relationship between the vibration parameters and the suppression effect,we establish the formula connecting the amplitude,frequency,acting length to the speckle improvement based on the rate of mode coupling.The experiment results confirm the trend:the suppression effect improving with vibration amplitude,and changing nonlinearly with the frequency、acting length.Therefore the rate of the mode coupling can evaluate the suppression effect qualitatively.The results provide theoretical proofs and experimental reference.

A Raman fiber temperature sensing system based on sample-ring aualanche photo diode (APD) gain adjusting and temperature calibrating method is proposed and experimentally demonstrated. The proposed system controls the APD bias by comparing the deviation of signal line and baseline obtained from the sample- ring, maintaining a substantially constant APD gain, thus ensuring temperature measurement accuracy and signal to noise ratio. Signal line obtained from the sample-ring is also used as reference signal for temperature calibration, further eliminating measured errors caused by inevitable APD gain fluctuation due to uncertain factors. Experimental results show that the proposed method significantly improves system performs in signal to noise ratio, stability and temperature measurement accuracy with respect to conventional Raman fiber temperature sensing system, it has practical value.

The fiber-optical coil is an important part of fiber-optic guidance weapon system.Due to the difference of the coefficient of thermal expansion(CTE) between the different composition materials,the performance of the accurate winding fiber- optic coil will be significant changed by the temperature.It is necessary to research the temperature matching performance of the fiber-optic coil,in order to ensure the structural stability and performance reliability.This paper presents a system to test the CTE by the double CCD camera,which is a non-contact test method.It uses the double light patch imaging amplification and sampling technology and gets the sample′s axial inflation volume in a temperature range by using the image processing method.In the paper,the test and analysis of the CTE of the off-spool fiber-optic coil,carbon fiber mandrel,polytetrafluoroethylene (PTFE) adjustment layer and the complete fiber-optic coil are finished by using the system.The results are the same in the theoretical analysis and the experiment,which proves that this test system is correct and feasible.

Aiming at the short comings of the existing Gaussian correction methods, the aberration constraint model is put forward to correct the lateral position displacement of transmission type optical system. The correction equation of zero aberration increment is deduced under the aberration constraint condition, and the corresponding lens selection principle is proposed. Zemax software simulation is carried out to validate this method. The results show that this method can reduce the influence of lens position change on the optical imaging quality.

A novel perspective slice method is proposed to solve the low resolution problem in reconstruction parallax images of holographic stereogram. The distance between holographic stereogram plane and viewing plane is set to be finite. A perspective slice is reconstructed by a holographic element (hogel), which is only a point in traditional holographic stereogram. The relationships between parallax image, perspective slice and the spectra of hogels are designed. The width of perspective slice is calculated from viewing distance and the size of hogels. The holographic stereogram with perspective slice is reconstructed by optical system based on a spatial light modulator (SLM). The experimental results demonstrate that the proposed method can enhance the resolution of the reconstruction parallax image by 8 times and represent the details of objects effectively. The influences of reconstruction distance to the quality of parallax images are analyzed.

A method to accurately locate projected center point from single circle image is proposed based on crossratio invariance principle and geometric constraint conditions in projective transformation. Take arbitrary circle secants, the relationship between the secant midpoint and the point at infinity is clear according to the harmonic conjugates and cross-ratio invariance. The equations which contain parameters of secant midpoints are established for solving secant midpoints based on the geometric constraints. Then the position of projected circular center is calculated. Compared with taking the center of projected ellipse as the center point directly, the proposed method does not have projection error. Simulation experiment results show that the accuracy and stability of the method is superior to the method of extracting ellipse′s center. The results of actual experiment show that the circular center positions are consistent with the positions extracted from the relationship among multiple circles, and the maximum position error does not exceed 0.8 pixel. The proposed method can locate the center of a single projected circle independently, which is suitable for wider applications.

The remote sensing images obtained by optical remote sensing camera are degraded and blurred due to atmospheric turbulence, imaging defocus, mechanical vibration. It is necessary to assess the recovery quality of image after the processing of remote sensing image recovery. An assessment method of sharpness is proposed, through the study of the skeleton of image edge detection, the number of pixel on the edge of abstracting the skeleton image is calculated. And the data is used as sharpness parameter of the images. Comparing the sharpness parameter of the recovery images with the distorted images, it is sure that the sharpness of the recovery images is improved. The experiment on remote sensing images demonstrates the validity and credibility of the proposed method, in the same time, it has better results in the noise resistance and the inhibiting effect of the weak ringing ripples.

Wavelet fusion method, wavelet basis and decompose levels play an important role in the fusion algorithm of multi-focus images based on wavelet transform. A new image fusion method based on local wavelet energy is proposed, some wavelet types and levels are analyzed and compared. The fusion parameters such as entropy, peak signal noise rate and spatial frequency are used to evaluate the fusion results. The results show that the new fusion method can get a better fusion results, bior2.2 wavelet basis and 4~6 levels are the best in image fusion, which provides some recommendation for wavelet basis selection.

The partial differential equations (PDE) filtering model is an important filtering method in electronic speckle pattern interferometry (ESPI) technology. The differential operator is often approximated by difference scheme in PDE models. Three kinds of difference scheme such as central difference, nine point difference and higher difference are introduced. The representative orientation second order PDE filtering model is selected and analyzed, approximating differential operator in PDE model with three different difference schemes using simulated fringe image, simulated phase image and experiment fringe image. The result indicates the high density region and sparse density region can be balanced preferably with higher difference for large density change image. Nine point difference and central difference schemes should be deposed with average filtering. The processing rate with central difference scheme is the fastest, the higher difference takes the second place, and the nine point difference is the slowest.

According to the needs of bionic polarized navigation to sky polarization pattern, a polarization imaging system, based on fish-eye lens with the field of view of 180° is designed to gather sky polarization information. Besides, the collected two-dimensional plane polarization pattern through Matlab software processing can revert to the spatial polarization pattern. The polarization imaging theories are introduced. The experimental instruments are calibrated, imaging formula and parameters of fisheye lens are obtained in the experiment And the images collected by polarization imaging system are corrected in the field of viewing. By using of the calibrated systems and imaging The spatial polarization pattern after calibration and correction is consistent with the single Rayleigh scattering theory model. And they are in a high degree of similarity, azimuth polarization can reach 82.4%, and the degree of polarization similarity is up to 96.91%.

The quality factors of cameras have a direct impact on the performance of video surveillance systems. It has attracted many research interests that how to quantitatively evaluate their performances rationally and effectively. There are many interdependent and interactional parameters that are employed to describe the demonstration of cameras, and hence, it is a complex problem. The main parameters affectting performances of video cameras including technology, function, subjective assessment and economy parameters are analyzed. The comprehensive evaluation of the camera imaging performance is attempted to decompose into three levels based on analytic hierarchy process, and then an evaluation mode is established. The influence of various factors for the mode is discussed and their weight values are calculated. The comprehensive evaluation results of several 1080P digital dome cameras applied to security protection have been obtained. It is expected to provide a reference for construction and running of video surveillance systems.

The essential principle of optical wavefront jitter for seeing- limited in large aperture telescope is presented.The mid and high frequency deviations from perfect wavefront are processed by power spectral density,which is used to evaluate the optic jitter.And it is applied to the plan wavefront measurement for laser,representing the jitter properties in frequency domain.This method contributes to the error analysis and budget of seeing limited optomechanical system and is useful as guidance for the evaluation of the wavefront quality.

In the visible light region,the ill- condition problem in particle size measurement based on spectral extinction technique is analyzed.By analyzing the results of objective function and inversion results,the influence of the ill-condition problem on spectral extinction method is discussed.The experiments are performed with standard polystyrene particles and the particle size distribution is inversed.Both simulation and experimental results show that the ill-condition problem in spectral extinction measurement is serious for the submicron particles.The situation of objective function extremum and inversion results are sensitive to error,leading to the poor stability and accuracy of the inversion results.To ensure the accuracy of the particle size measurement,measurement error should be minimized.In contrast,the situation of objective function and inversion results for micron particles is much better than for submicron particles.

Three-step spatial quasi-phase-shifting technique is able to demodulate the phase from a single frame of fringe pattern. This technique is suitable for dynamic fringe analysis. An improved three-step spatial quasi-phase-shifting technique is presented in this paper. According to actual situation, the number of pixels and the size of neighborhood are able to be tuned arbitrarily to calculate the phase of each pixel. It is conducive to the noise isolation, the error-propagation prevention, and the accuracy improvement in phase demodulation for dynamic fringe analysis.

A novel metal-dielectric-metal (MDM) waveguide based on the hybrid surface plasmonic polaritons (HSPPs) is proposed and numerically analyzed. This waveguide consists of two metal triangle wedge is placed on both sides of dielectric nanowires. Analytical and numerical calculations based on the finite element method (FEM) are carried out at the telecommunication wavelength λ = 1.55 μm . The numerical results show that it can confine light in the ultra-deep-subwavelength region with long propagation distance relative to the distance in the MDM waveguide without metal triangle. Detailed study of this structure reveals that these advantages originate from the tip enhancement of the triangle semiconductor waveguide. At 120°, its propagation distance increase 18% and mode area decrease 65%. So various applications will benefit from the hybrid plasmonic polariton waveguides, such as the laser, coupler and photonic integrated circuits.

To approach a high-efficiency, chip-size and widely tunable room temperature semiconductor terahertz (THz) frequency beating optical pumping beam source, an optical-integrated design is adopted. Two multipled distribute feedback (DFB) semiconductor lasers and a multimode interference (MMI) coupler are monolithically integrated on InP based substrate for terahertz frequency beating optical pumping beam generation. The designed Bragg wavelength spacing of the two DFBs is 4.8 nm (0.6 THz). The Bragg wavelength of the two DFBs can be tuned by the injected current. Each of them can red-shift by 3.9 nm. The output THz beating optical beam of the opticalintegrated chip can be coupled into the frequency resolved optical gate (FROG) through single mode fiber. By changing the injected current of the DFBs, room temperature THz frequency beating optical pumping beam source with a tunable frequency range of 0.184~1.02 THz is demonstrated.

An all normal-dispersion Yb-doped mode-locked fiber laser and its amplifier are demonstrated. The experiment system consists of two parts: nonlinear polarization rotation mode-locked fiber laser and amplifier with forward pump. In this experiment, a mode-locked fiber laser, whose repetition rate is 88.3 MHz, with the maximum average output power of 125 mW and 4 ps pulse width is obtained. After amplified, the maximum output power reaches 3.5 W on average, the pulse width and single pulse energy are 7.2 ps and39.64 nJ respectively.

The influence of pump wavelength on output power of 1064 nm laser is experimentally investigated. When the wavelength of pump source is 808 nm, the maximal output power of laser is only 20 W. However, when the wavelength of pump source is 888 nm, the maximum output power of 1064 nm laser can reach up to 33.7 W. In that case, the laser can work with single-longitudinal-mode owing to the nonlinear loss induced by the frequency doubling crystal in the resonator. The measured long term power stability and M2 are better than ±0.51% and 1.1, respectively.

A buried waveguide in LiNbO3 crystal is fabricated,by using the femtosecond laser which repetition rate is 25 MHz.The etching region can be divided into two regions which are inner interaction region and thermally modified region respectively.The coupling experiment shows two single mode buried waveguides are generated in the thermally modified region,and the propagation loss of the two waveguides are below 1.5 dB/cm.At the same time,the inner interaction region leading to a low transmittance.The Raman spectrum of the etching region is measured which shows the light-guide region is densificated by the thermal effect of high repetition,and there is a large-scale defects in the inner interaction region.

The design and fabrication of high power 980 nm ridge waveguide semiconductor laser diodes are described. To reduce the optical power density on facets, the broad-waveguide structure is designed. The 500 mW kink-free laser diodes is obtained by standard ridge waveguide laser diode process techniques, and the catastrophic optical damage (COD) level of the LDs is 560 mW.

In order to study on the influence on the optical-optical efficiency and slope efficiency of the mode match of pump and the laser beam in laser diode pumped alkali vapor laser (DPAL), based on the three level rate equation model, instead of the simplified model with average intensity in the medium, the spatial distribution of pump light intensity in the medium is used, and the one dimension DPAL calculation model considering the axial distribution of pump and the laser intensity and the three dimension DPAL calculation model are established considering the distribution of pump in the medium focusing caused by light intensity and the spot radius. The calculation results of the 1D model show that pump threshold in decreasing, the slope efficiency changes little compared with the simplified model. The calculation results of the 3D model show that when the pump mode volume all in the laser the slope efficiency reach the maximum, therefore in the DPAL actual operation, optimization of focal parameters and laser cavity parameters can improve the pump conversion efficiency.

A laser system design is presented for an absolute gravimeter based on 87Rb atom interferometer. By skillful design, lasers with 9 kinds of different frequency are based on two diode lasers including tapered amplifier. Two electrical feedback systems are used for laser frequency stabilization and generating the Raman lasers, respectively. All other lasers are based on two Raman lasers and realized with frequency shifting by acoustic optical modulators. This laser system not only has the compact and simple construction, but meets all the requirements for laser power and frequency controlling. It has the characteristic of reliability and integrity.

Based on the generalized Huygens-Fresnel diffraction integral formula, analytical expressions of coherent superposition multiple laser beams projection light focal spots intensity in hohlraum and wall of indirectdriven fusion device is calculated. The effect of the axial distance, defocus amount, incident angle and focusing F number on cavity internal glazing cross-section light spots intensity distribution and the effect defocus amount, incident angle, focusing F number and diameter on hohlraum wall light spots intensity distribution is analyzed. Simulation results show that within a fixed range, the interference becomes less obvious, and the intensity distribution becomes more uniform with the increasement of defocus amount and F number. In addition, the obtainment of better uniformity of light spots in hohlraum wall is relevant to hohlraum diameter and incident angle.

The key point of laser thermal loading test is to simulate the real temperature field on the top surface of the cylinder head with an easy,controllable,effective and accurate way.A kind of non-symmetric and non-uniform shaped laser beam is chosen as the heat source to irradiate on the top surface of the cylinder head,the simulated temperature field is consistent with the real one.The high cycle and low cycle thermal loading tests are realized.The test results show that the thermal loading tests can be effectively carried out with the temperature and time control models,which can provide the foundation for the fatigue life prediction.

Thin film polarizer reflects about 4%~5% p-polarized light,when the laser beam is incident on the thin film polarizer at Brewster′s angle,which makes the laser beam reflected by intra-cavity thin film polarizer contain depolarized light (s-polarized light)and unignorable p-polarized light.This will result in intra-cavity depolarization rate measurement inaccurate.Intra-cavity depolarization rate measuring inaccuracy caused by intra-cavity thin film polarizer reflecting p-polarized light in an outputting p-polarized Nd:YAG resonator is experimentally investigated.The results show that,for different output mirror transmission in a outputting p-polarized light Nd:YAG resonator,there is obvious difference between the measured depolarization rate plots,when the p-polarized light caused by reflecting effect of thin film polarizer is not filtered from the depolarized light.And that tends to be consistent,if the p-polarized light are filtered from light reflected by the thin film polarizer.The investigation also shows that,for a outputting s-polarized Nd:YAG,the the depolarization rate can be directly measured,because the depolarization light,which is s-polarized light,contains little p-polarized light.

In the process of laser design and use,the observed structure of the laser mounting plate can play a key role in stability of the laser output power.When applying a certain screw preload to the mounting plate,deformation of the mounting plate would generally result in the laser output power with varying degrees of change.In order to reduce the impact of the mounting plate deformation to laser output power stability,three mounting plates with different structures are designed to simulate the deformation of applying a certain screw preload by using the finite element analysis,respectively,and the corresponding output power is measured in several cases through experiments.The results of simulation and experiment show that,compared to the structure of untreated mounting plate and perforated mounting plate,the output power of the laser with side slotted mounting plate structure is relatively stable in the case of applying a certain screw preload.Therefore,the side slotted structure is a more stable and reliable laser mounting plate structure.

The 3 mm thick AZ31B magnesium alloy butt joints are carried out by fiber laser welding. Weld morphology, microstructural and mechanical characteristics of welded joints are investigated by means of optical microscope, scanning electron microscopy (SEM), tensile test machine and Vickers hardness tester. The results show that the weld zone width is narrow and weld appearances are smooth, but at the end of weld, the top surface collapse and back surface appear concave a little. The weld zone is characterized by fine equiaxed, and heat affected zone microstructures coarsen compared with the basemetal. The weld zone grain size increases according to the weld direction. The hardness in heat affected zone of welded joints is minimum, so the tensile samples without pore and crack defect rupture with ductile-brittle mixed mode in the heat affected zone. The ultimate tensile strength and elongation of is up to 95.1% and 89.3% of the basemetal.

In order to reduce the strong parallax false alarm rate of the moving target detection on a moving camera, a moving target detection method based on depth constraint equation is proposed. The relationship between twodimensional image coordinate and three-dimensional world coordinate is mainly studied. According to the image depth information and photography geometry theory, with the two frames image coordinates and the camera internal parameters, the depth constraint equation is established. The depth constraint equation includes gray value and depth information of image. Using the depth constraint equation to detect moving target can effective avoid the influence caused by moving camera. Experiments are performed based on actual image sequence, and related algorithm is compared and analyzed. Experimental results indicate that the proposed method can avoid the parallax false alarm and improve the precision of moving target detection on a moving camera is improved.

Ta2O5 is widely used as a kind of high refractive index film material.The optical constant is vary because of dispersion and absorption as well as different technological conditions.A kind of using electron gun of fabrication of thin film evaporation and ion beam assisted method is introduced.The test based on the Cauchy model of the films in the near ultraviolet to near infrared optical constants are fitted,and illustrates the application of the material in short wavelength pass filter.

The lattice parameters,band structures,density of states,electron density differences and optical properties of La,Ce,Nd doped SnO2 are studied by density functional theory (DFT).The computational results show that the bond length near La are greatest changed,while the change near Nd are least,which indicates the lattice distortion caused by rare earth doped in SnO2 is related to the covalent radius of doping atom.The band structure shows that rare earth doping can make the band gap of SnO2 narrow.The La doping makes the band gap reduced 0.892 eV comparing that of intrinsic SnO2,and Nd doping induces three energy levels in the forbidden band.The electron density difference shows that rare earth doping makes the electron redistribution of SnO2 and the iconicity enhance,especially the existence of f electrons.La atom loses electrons most and Nd atom loses least,which are consistent with the calculated results of band gaps.The calculated results of optical properties show that the imaginary part of the dielectric function and absorption function have a red shift,which agrees well with the calculated results of energy band gap.

This paper investigates the propagation of charge-2 vortex beam in 0-order and 1-order Bessel lattices induced by non- diffracting Bessel beams in media with focusing nonlinearity. Different stable ring- like vortex solitons can be generated when the lattice depth I0 matches the intensity of the bias electric field. Simulation results show that the vortex beam with topological charge m=2 can form the stable single-ring and multi-ring vortex solitons in a Bessel lattice.

Phase diversity is applied in the sensing of sparse-aperture systems. The accuracy of the wavefront phase estimation and the iteration time are researched by the image noise. The noise reduction is processing for the noise degradation images by the second order butterworth low-pass filter. Meanwhile the image spectrum by filtering and the optical transfer function are being as constraint with apodization to obtain the low frequency area of high signalto-noise ratio, and take the corresponding optical transfer function. The improvement of the object function for the phase diversity is derived after filtering by apodization. Digital simulation indicates that under the condition of different noise intensities, the proposed method can reduce the noise effectively and improve the phase estimation precision, the algorithm iteration time can be reduced simultaneously.

The history and current situation of magnetorheological finishing (MRF) at home and abroad are presented. The principle, characteristics and merits of MRF are introduced. Recent investigations of MRF at Changchun Institute of Optics, Fine Mechanics and Physics (CIOMP) are described in detail, and several key techniques of MRF are resolved. Our research findings include: A new-style magnetorheological (MR) polishing fluid is prepared, and the rheology and polishing power of this MR polishing fluid are improved evidently; dwell time algorithm of MRF based on matrix algebra is studied; in order to increase the area of removal function (polishing spot), improve the material removal rate, and polish large aspheric mirror, a new MRF concept, named Belt-MRF, is presented.

In order to ensure the high measuring precision of large-aperture flat mirror, the accuracy of the largeaperture reference flat mirror must be controlled strictly. The influence of different distribution of adhered spots and different support schemes on the shapes of reference flat mirror are analyzed by means of finite element method (FEM) under gravitational conditions. A kind of support pattern of 300 mm aperture reference flat mirror is designed. The mirror is supported by 12 adhered spots, and the best supporting method of mirror frame by rotation compensation is researched. The Φ 300 mm reference flat mirror is assembled according to the analysis above. The assembly results indicate that the change of optical surface due to supporting is nearly 1.294 nm of root mean square (RMS), which coincides with the analysis and satisfies the requirement of shape precision of the large aperture reference flat mirror.

The noncollinear acousto-optic tunable filter (AOTF) is a new type of spectral component that is developed according to the abnormal acousto-optic interaction principle. The spectral resolution and sidelobe of diffraction signal are two important indices for evaluating the performance of AOTF. The basic principle of doublefiltering using two AOTFs is described. The experimental results confirm that the double-filtering achieves a 40.4% to 83.2% improvement in the spectral resolution and from 9.5570 dB to 13.2407 dB suppression of the sidelobes. The results of this exploratory study demonstrate that double-filtering using two AOTFs has great potential for application in the field of the acousto-optic filtering.

Terahertz quantum-well photodetectors (THz QWPs) are photon-type detectors working in terahertz regime. Recent progress in the development of terahertz QWPs is reviewed in the following aspects. First, by considering the many-particle effects, the response peak frequency and the band structure of terahertz QWPs are calculated and optimized accurately; the electron transport behavior is explored within the self-consistent emissioncapture model. Second, three types of light couplers for terahertz QWPs are introduced. At resonant frequencies, the polarization of the light field is effectively tuned by the light couplers to fulfill the selection rule for intersubband transitions. The electric field intensities in the active multi-quantum-well (MQW) absorption region of terahertz QWPs are also enhanced. Therefore, the sensitivity of terahertz QWPs is improved. Third, the anomalous response peak at the longitudinal optical (LO) phonon frequency of GaAs is found in terahertz QWPs. Such response peak originates from the field enhancement in the MQW absorption layer mediated by LO phonons.

Magneto-optic modulation based on square wave signal has excellent properties, while it has the disadvantage of signal distortion. Theoretically, its mechanism is studied. Square wave signal is expanded into different frequency sine signal form by Fourier series. Magnetic fields of long solenoid driven by various frequency sinusoidal signals are calculated with Maxwell′s equations and Bessel′s equation. Various magnetic fields are added together and magnetic field of long solenoid driven by square wave is calculated in theory.

In terms of small target detection in hyperspectral imagery,two classes of small target detection algorithms in hyperspectral imagery are studied,analyzed and compared,which are categorized into fully self-adaptive detectors and semi-supervised detectors.To fully self-adaptive detectors,calculations show that anomaly detector and whiteddistance abnormity anomaly detector (WAAD) are better than low probability target detector (LPTD) and uniform target detector (UTD).To semi-supervised detectors,elliptically contoured distributions detector with hyperbola threshold (ECDHyT) is the best judging from the receiver operating characteristic (ROC) curve.The reason is that ECDHyT is based on the elliptically contoured distributions which can characterize target and background influenced by many factors more precisely.Comparison between the two classes of the algorithing is made.Target detection efficiency can be improved remarkably with even a little prior information about the target.

The effective extraction of radar echo signal is a key step in the process of Doppler signal processing in interior ballistics. Currently manual interception is usually adopted in the engineering application. The method often causes high error and low precision. Aiming at these problems, an effective method of Doppler signal automatic extraction is proposed. The obvious noise can be intercepted. According to the principle of Doppler, the method uses short-time Fourier transform (STFT) to acquire the velocity of the entire signal. The maximun velocity point is judged as the terminal point for the effective signal. The improved method of multiple-window energy ratio is adopted to determine the starting point. The experimental results through simulated signal and actual signal show that the average error of the method to extract the starting points and terminal points of the effective signal is 0.1875 μs.

Passively Q-switched solid-state lasers with high repetition rates can be widely used in many fields like precision laser radar,miniature laser source,environmental detection and fine processing,which have attracted considerable interests as narrow pulse laser source in recent years.The main techniques for improving the laser′s performance include passively Q-switched oscillator,actively-controllable passively Q-switched laser and power amplifier.In this paper,the domestic and international progress on high repetition rates passively Q-switched solidstate lasers are summarized from the above three aspects and the various embodiments of every scheme.In addition,the prospect and applications of the lasers are discussed in the article．

As one kind of photoacoustic spectroscopy technology, quartz-enhanced photoacoustic spectroscopy gas sensor has advantages of high sensitivity, high selectivity and rapid response. Tuning fork and micro resonance tubes is used instead of photoacoustic cell and microphone to realize quartz-enhanced photoacoustic spectroscopy detection. Micro resonance tubes is used for signal enhancement. Three types of coupling configuration mode between tuning fork and micro resonance tubes are analyzed and compared. The factors which affect the signal amplitude and signal to noise ratio are also analyzed. The progress in terms of parameters optimization is summarized. On basis of the analysis, the latest progress in spectraphone is also provided. In addition, a new type of terahertz quartz-enhanced spectraphone is introduced, which uses a custom made quartz tuning fork. With the development of mid infrared laser source，quartz-enhanced photoacoustic spectroscopy will not be confined by the limitation of beam quality , and will be used more widely.

Optoelectronic tweezers is a new kind of particle manipulation technology based on dielectrophoresis.Light pattern is projected onto a photoconductive layer with the photoelectric effect,and then virtual electrodes is generated on the layer,to manipulate particles.Compared with traditional dielectrophoresis manipulation,the most obvious feature of the optoelectronic tweezers is virtual electrode;it can be flexible controlled by graphics software.Through software,optical pattern can form on anywhere of the photoconductive layer,so as to achieve flexible control.Experimental system and working principle of optoelectronic tweezers are expounded,research progress and application in micro-nano manipulation are introduced.

Coherent light sources in the mid-infrared (mid-IR) range have broad practical and potential applications in spectroscopy, remote sensing, medical and military. Erbium(Er)-doped ZBLAN fiber lasers are well suitable for mid-infrared coherent light source at 2.7 μm. The latest progress of watt-level continuous wave (CW), high-power pulsed, wavelength-tunable, Q-switched and CW mode-locked Er3 +∶ZBLAN fiber lasers operating at 2.7 μm is introduced in this article. Finally, the development trends of the mid-infrared Er-doped ZBLAN fiber lasers are prospected.

The grating structure on metal contact electrode is designed to couple incident light into surface plasmon ploaritons, and a calculated approach is presented to quantitatively evaluate light trapping properties. It can be found that cube grating made by copper material can obtain the largest efficiency of thin film solar cell. The effect of the structure parameters of solar cell on the light trapping is discussed. An increasement in light trapping will be maximum with 30 nm height grating. The length of grating determines the width of peak in the light trapping spectra, and the period of grating determines the location of peak in the light trapping spectra. The results obtained have significance in further design to get more efficiency thin-film solar cells.

In order to improve the detection capability and accuracy of laser-induced breakdown spectroscopy (LIBS), the univariate and multivariate method [multiple linear regression (MLR)] are adopted to make quantitative analysis on Cr contained in samples respectively. Univariate analysis has been made by use of two characteristic spectral lines CrI: 425.435 nm and CrI: 427.48 nm, the limits of detection are obtained under the condition of five laser energies. The results indicate that the analytical results of CrI: 425.435 nm are better than CrI: 427.48 nm, the best limit of detection of Cr is achieved 5.8 mg/g. The linear correlation between the prediction and actual values of concentration of samples is discussed using MLR, the correlation coefficient is increasing to above 0.99 from 0.98 compared with univariate method. Using the approach of leave-one-cross-validation, the relative errors of prediction (REP) of univariate analysis of CrI: 425.435 nm and CrI: 427.48 nm are 6.73％ and 7.59％ respectively, while the REP of MLR is reduced to 4.66％ . The results indicate that LIBS combined with MLR can improve the accuracy of prediction on concentration of samples.

Copper thin films are deposited on K9 optical glass substrate by magnetron sputtering method. By X-ray diffraction, the structure of copper film are detected. By Ultraviolet (UV)-visible spectrophotometer and grating spectrometer, the optical absorption properties of copper film are detected. The results show that: for the same Cu thin films, the peak-number and peak position obtained by two different instrument are different. The peak of absorption spectrum is two obtained by grating spectrometer and has a "red shift" to that obtained by UV-visible spectrophotometer, this due to the different instrument resolutions and different light sources.

A laser-induced breakdown spectroscopy (LIBS) system is developed for the determination of heavy metals in cultivated land around the city of Baoding, China. The element composition of the soil is determined by a quantitative spectrum analysis. The results show that the concentrations of Cd and Hg in three base soil samples do not exceed the limits specified by the second- class soil standard“Environmental quality standard for soils”(GB 15618-1995) issued by the state.

Diamond-like carbon (DLC) film prepared by pulsed laser deposition is one of excellent means for antireflective and protective films of infrared (IR) window. DLC film on silicon is prepared by 248 nm nanosecond laser, and influence of pulse energy on optics performance, mechanical hardness and residual stress of DLC film are studied. According as experiments, IR transmission and surface hardness of the films both increase along with increasing of laser pulse energy, which indicates that high energy is propitious to prepare protective DLC film for IR window. However, residual stress in DLC film is also increased to reduce the adhesion strength of the film on substrate. This result supplies the practice base to the study on DLC film prepared by nanosecond pulse laser deposition.

An optical harmonic mixing system based on femtosecond laser technology is designed and built for ultrawideband microwave/millimeter wave measurement. In the system, femtosecond laser pulse train is utilized as the light carrier, and the signals under test are mixed with the high order harmonics of the femtosecond pulse envelope function, and then are down-converted into direct current (DC) for further measurement. Since femtosecond pulse train is characterized with wide-banded harmonics, the present system could cover a measurement bandwidth of 100 GHz. Aperture electric field amplitude distributions of 6.56 GHz and 100 GHz antennas are measured, respectively, using such system and the experiment results are corresponding well with electromagnetic simulations, which proves the correctness of the design. Besides, the harmonic mixer is achieved by using an electro-optical crystal(i.e. LiNbO3) based on Pockels′ effect.