As a new degree of freedom for light manipulation, the polarization state of a light field is gradually becoming a focused issue. The photon spin-orbit intercoupling can be achieved by the non-uniform modulation for the polarization state of the light filed, and then a variety of novel optical phenomena can be explored. Thereinto, the Pancharatnam-Berry (PB) phase plays an important role. In the polarization conversion, different polarization components of the light field are with different PB phases. We can control the transmission of the polarization components of the light field by using PB phases to shape the wave fronts of the polarization components, and achieve the polarization conversion, spin-orbit conversion, and energy flow management in the process of the light transmission. The related research of light polarization modulation has potential application values in spin-selected imaging, particle manipulation, laser micro-processing, and information transmission and recovery. We discuss the mechanism of transmission and manipulation of the polarization modulation light field, and present an overview of the recent research in this field.

An overview on the fundamental theory of optical coherence and its development history is presented. The methods for modulating coherence degree and coherence function and the methods for measuring laser coherence are introduced. Furthermore, the related physical effects induced by coherence modulation and fundamental applications are briefly outlined. Coherence modulation not only enriches the theory of light field modulation, but also pushes the development of laser technology.

Optical tweezers has become a powerful tool for research in life science and colloidal physics since its invention due to its advantages of mechanical contact-free and high-precision manipulation of micro-sized particles. However, the conventional single-trap optical tweezers is limited in the increasing demands of research. In recent years, the technique of spatial modulation of optical fields, which modulates the amplitude, phase and polarization state of light, has extensively enhanced the function of optical micro-manipulation, and promoted the advance in laser micro/nano fabricaton, optical sorting and transportation of micro-particles, and colloidal particles studies. The advance in spatial modulation of optical fields to date and their applications in optical micro-manipulation is reviewed, including the holographic optical tweezers, special-mode optical beams manipulation, and vector beams manipulation.

As an important technology for capturing and manipulating micro- and nano-particles, the optical tweezers rely on the basic principle of the mechanical effect of the momentum transfer between light and matter. It provides a non-contacting technique with a high precision, and has been widely used in physics, chemistry, biology, medicine and other scientific frontier fields. In recent years, surface plasmon polaritons have brought a new break-through for the development of the optical tweezers technology due to their excellent features of the near-field enhancement and the breakthrough of the diffraction limit, and become a very important and international frontier research direction. The new optical tweezers technologies based on the surface plasmon polaritons could be divided into the structure-based and the all-optical modulated surface plasmon polaritons, and each has its own advantages on particle trapping precision, trapping region size, dynamic and degree of freedom of manipulation. These new surface plasmon polaritons optical tweezers technologies attract researchers all over the world to carry out a large number of theoretical research and experimental exploration, show unique advantages on the trapping of nanoparticles and metallic particles and the enhancement and control of the near field electromagnetic field, and prove promising applications in the fields of biological sensing, surface enhanced Raman scattering, etc.

Recently, optical beam shaping has attracted intensive attention due to the fantastic properties and various applications of specific beams. These beams can be converted from Gaussian beams through particular spatial amplitude, phase or polarization control. In this work, a liquid crystal photopatterning technique based on dynamic microlithography with a polarization-sensitive photoalignment agent is presented. This technique enables the accurate, arbitrary and reconfigurable azimuthal angle control of liquid crystals, thus supplies a powerful approach for the tailoring of arbitrary fine microstructures with binary or continuously space-variant liquid crystal azimuthal orientations. Based on this technique, high quality vortex beams, vector beams and Airy beams are generated. Besides high efficiency, good electrical switchability and broad wavelength tolerance, the proposed devices also exhibit merits of compact size, low cost, dynamic mode conversion, and polarization controllable energy distribution. In this paper, our recent work on some specially designed patterns and corresponding specific optical fields is briefly reviewed. It may pave a bright way towards beam shaping and bring new possibilities for advanced liquid crystal photonic devices.

When light waves are scattered by a medium, the far-field optical properties including the spectral intensity, spectral coherence degree and spectral polarization degree, are closely related with the structure of the scattering medium. In recent years, much progress has been made in the research of weak scattering of light waves. On one hand, researchers have extended the scatterers to various scattering media, including the anisotropic medium, semisoft boundary medium, ellipsoidal medium, etc. On the other hand, the incident light waves are generalized to some commonly used light beams, such as the stochastic electromagnetic light wave, pulsed beam of the plane wave, non-uniform beam, etc. We introduce the main results of the research on weak scattering of light waves, including the spectral shift, spectral coherence, equivalence theory, reciprocity relation, inverse scattering, etc.

An ultrashort laser pulse will own different characteristic time distribution when its phase, amplitude or polarization is modulated in the frequency domain. These characterized ultrashort laser pulses are applied in the research of basic physical processes and optical devices. Benefiting from the development of photoemission microscopy, ultrasensitive spectroscopy and scanning near-field optical microscopy, the ultrashort laser pulse shaping technique has been more and more applied in micro- and nano-optics. This review summarizes the development of ultrashort laser pulse shaping and characterizing techniques and the usage of the ultrashort laser pulse shaping technique in scanning near-field optical microscopy, photoemission electron microscope and single molecule spectroscopy.

Optical vortices are a variety of cylindrical modes that have spiral phase terms around the optical axis. In recent years, optical vortices have attracted wide interest because of their potential applications in many areas including optical communications, optical information processing, imaging sensing, and quantum information. Compared to approaches based on free space optics, integrated photonics provides more effective approaches for the manipulation of optical vortices. This paper reviews the theoretical framework and latest progress in such approaches.

For decades, it has always been a dream of mankind to create self-bending of light in free space and even a boomerang of light as often seen in science fiction. Recently, Airy beams, along with their generalized self-accelerating beams, have attracted a great deal of attention due to their novel properties such as non-diffraction, self-bending, and self-healing. These unconventional optical beams not only have been realized in experiment, but also have wide application prospects, such as for particle manipulation, plasma channels, surface plasmons, electron acceleration, super-resolution imaging, transmission in turbulent environment, and guiding electric discharge. These application prospects make self-accelerating beams an attracting and exciting frontier of research. Here, we present an overview of the development and recent advances about self-accelerating beams mediated by phase modulation, including the generation and propagation properties of self-accelerating beams, and their extension and control in both spatial and temporal domains, with a focus on discussion of their novel applications in several areas.

Optical rectification (OR) is one of the most effective methods to generate broadband terahertz (THz) wave. The process of THz wave generation based on OR mainly depends on the interaction between the pump beam and the nonlinear crystal. The OR efficiencies in a 5 mm gallium phosphide (GaP) bulk crystal and a 6 mm GaP waveguide are compared between the central spot of a Bessel beam and a Gaussian beam with the same power. The experimental results show that the OR efficiency of the Bessel beam is 2.04 times larger than that of the Gaussian beam in the GaP bulk crystal, whereas the relative efficiency of the Bessel beam is increased to 3.46 times in the GaP waveguide due to perfect phase matching between the pump beam and the THz wave. The THz wave fields generated by both pumps have a Gaussian distribution, and the THz spectra generated by the Bessel beam have obvious red shifts. The fact that the Bessel beam could improve the OR efficiency will be helpful for achieving high-power and compact THz sources, which is valuable for various THz applications.

Double-pass propagation path of residual turbulence scintillation lidar in turbulent atmosphere is studied and the expression forms of residual scintillation index acquired at the receiving terminal are obtained under the monostatic and bistatic cases, respectively. Under the condition of large aperture, the scintillation index of double-pass path is just scintillation index of spherical wave caused by the uplink path turbulence effect. By an experiment of horizontal comparison between residual turbulence scintillation lidar and scintillometer, the theoretical results are verified.

The spatial filter in the beam shaping system of a 2 kW radio frequency slab CO2 laser is used to eliminate side lobes and improve quality of output beams. It is important to study the effect of misaligned spatial filters on the characteristics of the shaped beam. The effect of the misaligned spatial filter on intensity distribution of the shaped beam was studied theoretically and experimentally. The theoretical simulation results are in agreement with the experimental results. Meanwhile, the effect of the misaligned spatial filter on output power of the shaped beam was studied by theoretical simulation. The results show that the effect of lateral displacement in the unstable direction of the spatial filter on the output power and the intensity distribution of the shaped beam is significant. The output power decreases and the side lobes appear as the lateral displacement increases. The shaped beam is not a circle while the spatial filter is axially-misaligned. The diameter difference is up to 3 mm when the axial displacement is 10 mm. The angle misalignment of the spatial filter mainly has impact on the shaped beam in the waveguide direction. The side lobes appear and the beam quality decreases as the angle misalignment increases. The loss of output power is up to 25% when the angle misalignment is 10°.

Based on the special two-dimensional flexible structure，graphene has excellent optical and electrical properties. With the finite element method, we theoretically investigated modulation of the optical field of graphene covered microfiber. By changing the overlay angle, the symmetrical structure of fiber was destroyed to provide the microfiber with birefringence. The value of birefringence is a function of overlay angle. The chemical potential of graphene can be modulated and the light transmission of optical fiber can be switched by changing the external voltage. We designed a graphene covered microfiber based electrical absorption modulator and proceeded the performance analysis. Numerical simulations show that when the overlay angle is 270° and the incident wavelength is 1550 nm,the birefringence can be up to 1.23×10-3. When the electric absorption modulator works at the wavelength of 1550 nm, its length is 18 μm, the extinction radio is 7 dB, the 3 dB bandwidth reaches 927 MHz, and the insert loss is 0.58 dB.

Difference of the modulation transfer function for long-exposure imaging between the oceanic turbulence and the atmospheric turbulence is compared. Applicability of the modulation transfer function for short-exposure imaging (SEMTF) in the oceanic turbulence is discussed. Moreover, effects of the oceanic turbulence parameters on the system resolution are studied in detail. Results show that the quality of imaging is better in the dominating temperature-induced turbulence than that in the dominating salinity-induced turbulence, i.e., the image contains more high-frequency components of the original image. The SEMTF study based on the Fried short-exposure theory is defective in the high-frequency region, but the applicability of SEMTF can be enhanced as the ratio of lens diameter to the spatial coherence radius and the path length increase. In addition, the resolution of imaging decreases, i.e., the quality of imaging is degraded, as the ratio of temperature and salinity of the seawater power spectrum increases, the dissipation rate of the seawater temperature variance increases, and the dissipation rate of the seawater unit mass turbulence kinetic energy decreases.

The intensity distribution and the wander of optical vortices of Laguerre-Gaussian beams propagating in turbulent atmosphere are simulated numerically. The results indicate that intensity profiles of vortex beams experienced successive variation from annular structures to flattened-top profiles and finally to Gaussian profiles with the propagation. The variation is closely related with the propagation distance, the turbulence strength, the outer scale of turbulence, the number of topological charge, the width of beam waist and the wavelength of vortex beam. However, the variation is nothing to do with the inner scale of turbulence. The wandering behavior of optical vortices in the atmosphere is described by the occurrence number on a transverse plane. The results show that the occurrence number on the receiver plane follows Gaussian statistics. As the propagation distance, the turbulence strength, or the topological charge of the vortex beam increases, the Gaussian fitting curves become broader, and the statistics of vortex position tends to random distribution. In addition, choosing the suitable width of the vortex beam waist can reduce the wander of optical vortices.

Based on the generalized Huygens-Fresnel principle and the rough surface scattering theory, the effect of atmospheric turbulence on both pulse beam propagating to the target and scattering field propagating back to the receiver is studied, and the second-order statistical properties of pulses scattered by diffuse targets are investigated. An expression is deduced for the multiple-frequency mutual coherence function (MCF) of a reflected pulse beam from the rough target in atmospheric turbulence. According to MCF an expression of the mean intensity and the degree of complex coherence at the receiver is derived. The numerical simulation results indicate that the mean intensity is independent on the atmospheric turbulence, and the coherence bandwidth depends on the turbulence strength, the central angular frequency, the outer scale of turbulence, the position separation and the angular frequency difference when the phase structure function is dominant.

In traditional direct imaging a scattering medium between the object and detection system will severely degrade the image quality. Computational correlation imaging (GI) has a unique advantage in that the effect of the light scattering can be greatly reduced. We present an analysis of computational correlation imaging and traditional direct imaging (TDI) with a turbid medium in various locations in the beam paths. It is found that a scattering medium in the illumination path will decrease the reconstructed imaging quality, while if it is only in the detection path it has almost no effect. Experimental results with a scattering medium in both the illumination and detection paths show an improved contrast-to-noise ratio of 2.98 compared with 2.72 for conventional direct imaging. These results are important for imaging objects embedded in media such as fog, smoke and cloud.

A phase mask is designed by vortex beams and the transmissivity function of an axicon, and the plane wave is irradiated to the spatial light modulator (SLM) into which the phase mask is written. The perfect vortex beams are generated on the Fourier plane of SLM, and then the overlap between the 0 order and the ±1 order spectra on the Fourier plane is solved. A space free-control technology for perfect vortex beams is proposed. By analyzing the experimental data, the functional relationship between the spatial displacement and the adjustable factor is determined, and the control precision achieves 2.25 μm. Furthermore, by adjusting cone angle parameters of the axicon in situ, the center bright ring radius of the perfect vortex beam could be controlled freely. The quadratic functional relationship between the radius of the center bright ring and the cone angle is obtained. The perfect vortex beams, which are generated by the incident lights with wavelengths of 532 nm and 632.8 nm, are compared. Results show that the perfect vortex beam with a smaller radius can also be obtained by a longer wavelength incidence. The study is expected to inspire new applications of the perfect vortex beams in micro-particle manipulation, optical information coding, optical measurement, fiber communication based on orbital angular momentum.

The output efficiency of terahertz wave based on the tilted-pulse-front geometry by controlling temporal and spatial chirps of pump pulses is improved theoretically and experimentally. For the situation of the additional temporal chirp, the results show that the output efficiency of terahertz wave is nonlinear to the additional positive chirp of pump pulses and there is an optimum selection. However, it is linearly inversely proportional to the additional negative chirp of pump pluses. For the situation of the additional spatial chirp, the results show that the output efficiency of terahertz wave is always decreased, regardless of the size and sign of the additional chirp. Furthermore, the dramatic decrease of the output efficiency appears with the increase of the spatial chirp. These results have a guiding significance for the optimization and regulation of the ultrafast terahertz wave system based on the tilted-pulse-front method.

The phase function of a target curve is obtained using the Legendre transform and used to determine the position of graded grooves. In addition, the spatial arbitrary bending beams are generated by the interference of surface plasmon polaritons propagating on graded grooves. The effects of structural parameters are investigated. The results show that the intensity, shape and distance of propagation of spatial arbitrary bending beams rely on the constancy of target curve and the depth and width of the grooves.

Based on statistical similarity theory, the corresponding polarization properties of complete coherence defined by Wolf and Setl are studied respectively by using the relationship of light field component of two points hidden by complete coherence. The polarization degree characteristic of light field included by complete coherence and the polarization state distribution characteristic of the polarized portion are analyzed. Then the analytic expressions of the linear characteristic of light field component, ellipticity and azimuth angle are derived. The simulation experiment are carried out at last. Results show that based on the complete coherence defined by Wolf, the polarization degree of the random field at the two points is an arbitrary value, but the value and the degree of the cross polarization are exactly the same. Based on the complete coherence introduced by Setl, the random field at the two points is completely polarized, but the polarization state does not exhibit the same character, and there is no association between ellipticity and azimuth angle.

A new method which can generate hollow beams by focusing J0-correlated Schell-model beams with an axicon is proposed. The light intensity distribution of the J0-correlated Schell-model beams after the axicon is simulated with the cross-spectral density function. The results show that the sizes of the hollow beams increase with the increasing propagation distance. The self-reconstruction property of the hollow beam is investigated by the Tracepro software. The correlation experiment is carried out. The results of the experiments are in agreement with those the theoretical analysis and the numerical simulation. This study will be a reference for applications of optical tweezers.

Based on the first-principle, the geometrical structures, electronic structures and optical properties of FeS2 doped with and without Cu/Co are calculated and analyzed, respectively. The analysis results indicate that, as for the doped FeS2, its lattice constant increases, band gap decreases, and electrical conductivity enhances. After doping, the main peaks of imaginary part of dielectric function, absorption coefficient, and energy loss spectrum are all red-shifted, and peak values all decrease. As for co-doped FeS2, the optical transition intensity obviously enhances, and the light absorption coefficient and photoconductivity in visible region both increase, which indicate that Cu-Co co-doping can significantly enhance the photo absorption of FeS2 and increase the photoelectric conversion efficiency.

At present, we have achieved a very high modulation depth, but it is unable to realize wave shaping for the lack of research on tunable modulation depth. On the basis of electrical tuning of graphene and the resonance property of graphene metamaterial surface plasmon polaritons (SPP), a graphene metamaterial modulator of tunable modulation depth at a frequency is proposed and the modulation depth is the maximum value, which is convenient for sampling and testing. The transmission law is theoretically analyzed by using the harmonic oscillator model. Based on the simulation of three-dimensional simulation software time domain solver, the series of modulation depth corresponding to the frequency of 11.85 THz is obtained, where the maximum modulation depth is greater than 96%. The series of the modulation depth can be modulated and transformed by bias voltage regulating graphene Fermi level. This will greatly promote the application of modulator in the wave shaping, such as generating sine wave, triangle wave and square wave. In addition, this structure can achieve a similar electromagnetically induced transparency (EIT) phenomenon. It can not only achieve the frequency shift and the transmission peak broadening, but also keep the center frequency the same before and after broading center frequency.

The spectropolarimetric imaging system based on three photoelastic modulators and one acousto-optic tunable filter (AOTF), has many components, limited field angle of AOTF and uneven spectral distribution in one image. To overcome the disadvantages, an optical imaging system is reported, in which the front optical system is composed of convex lens, concave lens and convex lens. The field angle of measured target is compressed so as to satisfy the requirement of the AOTF field angle. The parallel incident light of the target is changed to parallel light incident into AOTF for subsequent spectral correction. Target light at different positions enters the optical system and AOTF with different incidence angles, and the imaging positions on CCD are also different. Since the central wavelength of the AOTF diffracted light is related to the incidence angle, the relationship between them can be determined by fitting, which further identifies the relationship between the central wavelength and the CCD pixel. The spectral correction method is analyzed in detail. The experimental results show that the error of corrected spectral value is reduced by an order of magnitude compared with that of the common AOTF spectral imaging system. The spectral imaging results are clear and the accuracy of the spectropolarimetric imaging measurement system is improved.

In order to reduce the requirement of the application of polarization imaging technology, a method of material classification under ambient lighting condition is proposed. According to the Fresnel law of reflection, there are some polarization components with the reflected light on target surface. The azimuth angle between detector and reflector is obtained by detecting the polarization angle, horizontal and vertical polarization degree of the detected surface is obtained by compensating the four directions of the polarizer. The target material can be sorted out by measuring degree of polarization of reflected light and reflectivity ratio. The reflection polarization degree and reflectivity ratio of rubber plate and metal plate are simulated and experimental researched, the results show that there is obvious difference of reflectivity ratio between metal and nonmetal in a certain observation angle range, and the metal and nonmetal targets can be distinguished effectively by using Fresnel reflectivity ratio as a discriminated parameter.

Segmentation of retinal images obtained by optical coherence tomography (OCT) and retinal thickness measurement has become an important clinical diagnostic tool for many diseases in ophthalmology. However, such factors as speckle noise, low image contrast, and irregularly shaped structural features including blood vessels make it difficult to segment retinal layers accurately. An automated retinal layer segmentation method is proposed by employing block-matching and 3D filtering along with mean filtering for preprocessing and a two-step optimal search. The two-step optimal search begins with individual retinal layer segmentation by setting a variable threshold on each A-scan as initial results, which are then checked and corrected for continuity and integrity. The performance of the proposed method is tested on a set of OCT retinal images acquired from healthy people and patients. The experimental results show that the proposed method provides accurate segmentation of nine retinal layers whose mean boundary position deviation is (1.34±0.24) pixel. The method can be applied to OCT images affected by speckle noise, low image contrast, and even irregularly shaped structural features such as blood vessels.

As the previous clutter metrics have such problems as extracting the weight value from the fixed experience and taking no consideration of the human visual response, they cannot measure the background clutter accurately. We propose a new clutter metric, in which the optimal response threshold is introduced to simulate the adaptability of the human eye to the clutter response. The optimal response threshold is also used to evaluate the effect of the background similarity on the target acquisition performance so as to measure the clutter. The proposed metric is tested by the Search_2 database. The testing results demonstrate that the target acquisition performance prediction based on the clutter metric is in accordance with the subjective data. The mean square error of the target detection probability is 0.0835, and the correlation coefficients are 0.7124 and 0.7444; the square mean error of the target false alarm rate is 0.0691, and the correlation coefficients are 0.7874 and 0.6753; the square mean error of the target search time is 3.2321, and the correlation coefficients are 0.7630 and 0.7710.

High resolution is one of the goals that optical microscopy techniques always pursue till now. Despite the current innovations of microscopy systems′functionality and performance, the confliction between high resolution and large field-of-view has become increasingly prominent, limiting its applications greatly in many areas. As a new-type computational imaging method, Fourier ptychographic microscopy (FPM) has been introduced in recent years, which provides a wide-field high-resolution imaging capability by recovering the intensity and phase distributions simultaneously. Although FPM has just been proposed in 2013, it has received extensive attention and researches in the field of optical microscopy, biomedicine, and life sciences because of its large field of view, high resolution, quantitative phase imaging and many other advantages. A review is given to introduce the research status, applications and some recent advances in FPM from its basic principles, experimental systems and imaging modalities, advanced recovery method of system and algorithm. The changeling problems as well as future research directions are also discussed.

A Brillouin optical time domain reflectometer sensing system is proposed based on external modulation of the multi-longitudinal mode Fabry-Perot laser and frequency-shifted local optical heterodyne detection. The principles of stimulated Brillouin scattering threshold improvement and heterodyne detection of frequency-shifted local light from the same laser and Brillouin scattering from the sensing fiber are analyzed, and the mathematical expression of signal-to-noise ratio of the system is deduced. The dependence of the peak power and bandwidth of superposed Brillouin spectrum, the signal-to-noise ratio and the measurement accuracy of Brillouin frequency shift on the longitudinal mode number, and the relationship between the longitudinal mode number and the optimal measurement accuracy for different pulse widths are theoretically studied. The corresponding fitting formulas are obtained by calculation. The results show that with the increase of longitudinal mode number, the signal-to-noise ratio, temperature and strain measurement accuracies of the system at the end of 25 km long fiber are improved significantly for a multi-longitudinal mode Fabry-Perot laser with a mode interval of 0.141 nm and a pulse with a peak power of 100 mW and a width of 50 ns for single-longitudinal mode. Especially, compared with single longitudinal mode, the signal-to-noise ratio increases by 11.73 dB, and the optimal temperature and strain measurement accuracies of 3.2 ℃ and 70.8 με are achieved, respectively, when the longitudinal mode number is 20. The optimal measurement accuracy of Brillouin frequency shift rises rapidly with the increasing pulse width, and the optimal measurement accuracy tends to a constant of 2.9 MHz for pulse width larger than 100 ns.

A specialized dynamic distillation and purification process is used and cooperated with the optimized homogenized melt and the low-temperature quenching techniques to obtain high purity As40S60 and As38S62 glass. Then an efficient extrusion method is applied to the preparation of a core-cladding chalcogenide optical fiber preform. After that, under the protection of the polymer, which is polyethersulfone (PES), the preform is drawn into the As40S60/As38S62 core-cladding structure chalcogenide optical fiber with precise proportion, eccentricity closing to zero and low loss. After the high pressure extrusion process, the defects in the core-cladding interface are nearly eliminated, and thus the fiber loss is reduced effectively. The experimental results show that the infrared transmittance of As40S60 glass is obviously improved after effective purification and most impurity absorption bands in the spectra disappear. After the surface of fiber input ends is coated the Ga layer, the standard cut-back technique is adopted to measure the attenuation of this As40S60/As38S62 fiber. The transmitting background loss is around 0.2 dB/m, and the minimum loss is about 0.13 dB/m at 4.8 μm.

By molecular beam epitaxy technology, reflection-mode (r-mode) and transmission-mode (t-mode) GaAs photocathode samples with identical uniform doping or exponential doping are prepared. Their spectral response are measured based on the on-line spectral response measuring system and via fitting to the experimental curves, the electron diffusion length and integral sensitivity are obtained. These results indicate that, after the cathode module processing of the t-mode sample, the decrease of the electron diffusion length for sample with uniform doping is twice that for sample with exponential doping, the reduction of the integral sensitivity for the latter is smaller by 3% than that for the former. The exponential doping way is beneficial to reducing the influence of cathode module process on photoemission layer of photocathode materials.

PIN is a common modulation structure in the electro-optic modulator, and the thermo-optic effect in work directly affects the performance of electro-optic modulator. In order to alleviate the thermo-optic effect, the principle of PIN modulation is firstly researched. A novel structure of waving PIN modulation based on silicon on insulator (SOI) material is invented, and the new structure is compared with ordinary PIN modulation structure. The influence of the waving PIN structure on temperature, refractive index, carrier concentration of modulation area are quantitatively analyzed. At 2 V voltage modulation through simulation, the temperature of waving PIN structure is reduced by 11.6%, the refractive index drift is reduced by 28% through restraining the thermo-optic effect, and injection carrier concentration of modulation area is increased by 26.7%. Finally, the waving PIN micro-ring electro-optic modulator and ordinary PIN micro-ring electro-optic modulator are respectively fabricated and tested. The test results show that the waving PIN structure has greater shift values of resonance peak and can effectively restrain the thermo-optic effect. The advancement of the novel structure and the correctness of theoretical analysis are verified.

Considering the non-equilibrium heat transfer characteristics between electrons and lattices in the process of laser heating, a two-step lattice Boltzmann method (LBM) equation is established by combining the LBM and the two temperature model. Then the thermal response characteristic of a nano-film irradiated by the short-pulse laser is simulated using this method. The change law of temperature distribution in thin film with time and space is analyzed in the irradiation process. In addition, the effects of the laser intensity and the thin film thickness on the thermal response are also discussed. The results show that there exists a significant hysteresis phenomenon between the changes of the lattice temperature and the electron temperature in the irradiation process, and the calculated electron temperature response and damage thresholds are agree well with the experimental results. Those indicate that the proposed two-step LBM equation can describe the non-equilibrium heat transfer phenomenon between electrons and lattices in the process of the laser irradiation well. It is also found that with the enhancement of the laser energy and the decrease of the film thickness, the electron and lattice temperatures of the film surface are significantly increased, and the time at which the electron and the lattice temperature achieve stability are also delayed.

Due to the limitation of various conditions in the actual measurement, such as non-ideal 5050 beam splitter, balanced homodyne detector and interference efficiency, which are adverse to characterizing the squeezed state by the balanced homodyne detection (BHD) system. On the basis of the theoretical background of the BHD, the influence of the non-ideal BHD including the splitter ratio of 5050 beam splitter, the common mode rejection ratio (CMRR) of BHD and the interference efficiency on the measured squeezing degree are analyzed quantitatively, and the function of the deviation value is built with the real squeezing degree, splitter ratio of 5050 beam splitter, interference efficiency and CMRR. The result is very important for quantify the measuring error, and infer the real squeezing degree from the measured squeezing degree.

An adaptive temporal compressive sensing for video based on signal correlation is proposed, which can judge the motion of the object adaptively and reconstruct the signal targeted in the process of the super time resolution video imaging. The proposed method separates the observed image into regions of different amount-of-movement, and then reconstructs these regions with targeted dictionaries, which are trained from corresponding video samples. In the process of video reconstruction, block reconstruction of the coded exposure video is being done. This fast reconstructed video is used to compute the correlation coefficients between the neighbor frame image blocks. Local motions are then estimated by the correlation coefficients, and finally, the dictionaries can be adaptively selected according to the motion information to reconstruct the video. Simulation results show that the proposed method can obtain the motion distribution accurately, and the quality of the reconstructed video is increased while the reconstruction time is reduced.

Based on the generalized Huygens-Fresnel diffraction integral formula, field distribution expression of sinh-Gaussian beams passing through astigmatic lens is derived. The intensity distribution and the phase characteristic of sinh-Gaussian beam on focal plane or near focal plane of astigmatic lens are numerically calculated. Theoretical analysis and numerical calculation results indicate that the appropriate beam parameters and astigmatic lens structure parameters can make sinh-Gaussian beam passing through astigmatic lens transform into dark hollow beam with vortex. Its topological charge index is 1. Besides, the beam parameters and the lens coefficients affecting the field intensity distribution and phase distribution are discussed. It is found that the astigmatism of lens plays a critical role in converting sinh-Gaussian beam into a dark hollow beam with vortex through focusing of astigmatism lens, and a super-long dark hollow beam can be obtained with the astigmatic lens.

Aiming at the complex structure, poor reliability and high cost of the large special carrier position and attitude measurement system, a new method for precise measurement of carrier navigation information is proposed by using the two-level integrated navigation of satellite navigation and celestial navigation based on the fiber optic gyroscope (FOG) strap-down inertial navigation system (SINS). The filtering structure, error equation and mathematical model of the integrated navigation system are presented. The results of data analysis and accuracy assessment show that the integrated navigation method, based on FOG SINS with small size, high reliability and low cost, can achieve the precise measurement of carrier velocity, position and attitude. The precise measurement method of carrier position and attitude based on FOG SINS is an effective way to realize low cost and high performance of navigation.

Ptychography, a phase retrieval technology based on scanning coherent diffractive imaging, shows such advantages as simple experimental setup and strong anti-noise ability. Ptychography is used in the field of wavefront metrology for projection lens. The formulas of optical field propagation, the conditions of discretion, and the experimental configurations are analyzed in detail for projection lenses with different numerical apertures. Numerical simulations and experimental results show that to achieve reasonable convergence and measurement accuracy, the transmittance of the object should be set between 45% and 80%. Increasing the complexity of the object pattern and adding registration process of probe and object into the iterative algorithm can also improve the convergence speed and the recovery accuracy. The wavefront aberration measurement accuracy can reach 10-3λ or less. It is feasible to use ptychography in wavefront aberration measurement for extreme ultraviolet lithographic projection lenses.

A novel method combine epipolar constraint to speckle correlation for real-time three-dimensional measurement is presented. Random digital speckle is embedded in the sinusoidal fringe patterns and three-phase-shift is proposed. The period of phase in each pixel is resolved by means of epipolar constraint. Using the theoretical minimum of three images, the phase ambiguity is eliminated and the absolute phase is recovered. Experimental results indicate that the proposed method improves the accuracy of the phase unwrapping immensely compared with the traditional information-embedded and multi-camera constraint methods. In order to improve the operation efficiency of the algorithm, the graphics processing unit parallel computation based on parallel computing architecture is introduced to optimize the algorithm. And the system achieves real-time three-dimensional measurement at average speed of 26 frame/s with a resolution of 94,163 points per frame.

The dynamic response of heat sink in the measurement process by an absolute cryogenic radiometer is studied with the finite element method, the key factors affecting the equilibrium temperature of heat sink and the temperature variations under different heat sink structures are analyzed, and the thermal responses when 304 stainless steel, 6061 aluminum alloy, and oxygen-free high-conductivity copper are respectively used as thermal links are compared. The results indicate that, a heat link with low heat capacity and thermal conductivity is the first choice in the future of cryogenic radiometers. In addition, the equilibrium temperature of heat sink can be effectively controlled via suitable adjustment of the heat sink structure.

Computer-generated hologram (CGH) plays an important role in testing high-accuracy optical elements such as aspheric and freeform surfaces. However, the orthogonality error induced by the rails of direct laser writing systems will deteriorate the fabrication accuracy of CGH, and thus introduce astigmatism error to the testing results of surface shape. To quantitatively study the influence of orthogonality error induced by the rails of direct laser writing systems on testing results of CGH, a model of rails′ angle error of direct laser writing systems using scalar diffraction theory is established, and the impact of orthogonality error on the alignment section of the CGH is analyzed. The experimental results indicate that there is 2.26%, 2.33% and 1.72% deviation in root mean square(RMS), peak valley(PV) and Zernike astigmatic coefficient respectively with theoretical results when orthogonality error is 800 μrad, which verifies the correctness of the established error model.

A high-energy laser system with self-sustaining adaptive optics is designed, which uses active illumination detection method of high-energy laser to detect target. However, the echo field received is affected by speckles, and a physical model of the detection system is established to analyze speckle effect. The average scale of speckle is discussed based on the autocorrelation function of speckle intensity. The complex coherence function of speckles on the receiving plane is defined via the partial coherence theory, and the width of complex coherence function in the integral field with different scales of speckle patterns is discussed as well. The imaging magnification of target and the ideal resolution are derived, and the relationship between the image scale and the light spot scale on the focal plane is discussed. The effect of the spot array on the focal plane with different scales of speckles is analyzed by numerical simulation. By superimposing atmospheric turbulence, the effect of speckle field on the atmospheric turbulence detection is confirmed. The results show that the speckle scale between subaperture and large aperture is the best design, when the system has both high displacement measurement precision and high overall detection rate.

In infrared polarization remote sensing detection system, the infrared polarization characteristics of the target are affected by atmospheric environmental factors, which influences the inversion scene polarization parameter. So a model of infrared spectrum polarization parameter correction algorithm is proposed to control the influence of the atmosphere, which is based on infrared polarization transmission theory. The atmospheric effective transmission model is established by analyzing the atmospheric radiation and transmission characteristics. Several factors, such as the band range, atmospheric environment, transmission path and temperature, etc., which influence the effective transmission rate, are studied, and the polarization parameters are corrected according to the effective atmospheric transmittance model. Analysis of experiment shows that the correction algorithm model could effectively inhibit the impact on the infrared polarization parameter measurement during atmospheric transmission, and it can reflect the scene polarization characteristics more accurately. The detecting and recognizing abilities of infrared polarization remote sensing are improved.

In order to realize the three-dimensional positioning function of the industrial robot to target objects, a novel structured-light vision guided industrial robot positioning system is proposed. Structured-light auto-scanning measurement module consisting of industrial camera, laser, and galvanometer is used as the vision senor of the positioning system. By scanning target objects with laser plane through the rotation of the galvanometer, the three-dimensional pose of target objects in camera coordinate is obtained. For the conversion of target objects three-dimensional pose from the camera coordinate system to the robot tool coordinate system, a simultaneous calibration scheme of the robot hand-eye relationship and the tool coordinate system is put forward. The three-dimensional positioning function of the industrial robot to target objects with random position and orientation can be implemented. Experimental results show that the proposed system has high positioning accuracy, and its flexibility and accuracy can meet the requirements of industrial applications.

Confocal Brillouin microscopy device is set up, and Brillouin scattering light of sample is excited using a single-mode laser of 532 nm wavelength. The amplification factor is 100× and the numerical aperture is 0.8. A tandem scanning multi-channel Fabry-Perot (F-P) interferometer is used to collect Brillouin light. In the experiment, the confocal light intensity response curve is measured and the Brillouin spectra of SiO2 glass, silicon rubber, and polymethyl methacrylate (PMMA) are obtained. Using a novel photon number component factor data process method, the axial imaging resolution is simulated and analyzed. The axial imaging properties of frequency shift, axial acoustic velocity and longitudinal elastic moduli of multi-layer sample of SiO2 glass-silicon rubber-PMMA are also presented. Error analysis of these three parameters of axial imaging property curve by this method is made as well. The simulation results show that the axial imaging resolution can be improved to about 2 μm with this novel photon number component factor data process method. When the signal-to-noise ratio is greater than 1.46 dB, the accurate Brillouin frequency shift, axial acoustic velocity and longitudinal elastic moduli can be obtained by error relation curves.

To improve the non-uniformity of infrared output images, the two-point correction and neural network algorithms are commonly used. However, the two-point correction algorithm cannot overcome the influence of environmental temperature drift effectively. Due to the slow convergence speed of the neural network algorithm, the still images using the neural network algorithm gradually integrate to the background, and the moving target appears an artifact. So a multiple background sampling adaptive non-uniform correction algorithm is proposed, and multiple groups of high- and low-temperature backgrounds are collected at different temperature points. The relationship between the achieved non-uniform correction coefficient and the environmental temperature is fitted by means of the least square method, and the adaptive non-uniform correction is implemented based the change of the environmental temperature. Test results show that this method is simple and feasible, and it can effectively overcome the influence of environmental temperature drift.

A composite method is proposed to correct the astigmatism, which aims at the problem that the astigmatism of the wide band of the Czerny-Turner structure spectrometer is hard to correct at the same time. With the new approach, when the ability of the first-order astigmatism correction reaches the limitation on wide broadband wavelength, the astigmatism opposite trend of added cylindrical lens is used to further compensate the residual astigmatism in the optical system. The astigmatism compensation formula on marginal waveband of with composite method is deduced. With the composite method, an anastigmatic Czerny-Turner structure on near-infrared waveband ranging from 900 nm to 1700 nm is designed. The simulation results of Zemax show that the root-mean-square (RMS) value of full-band and full fields of view is less than 14 μm, modulation transmission function (MTF) is higher than 0.7, and the spectral resolution is 1.5 nm at all wavelengths. The composite method achieves simultaneous correction of astigmatism at near-infrared 800 nm wide waveband, which can avoid energy transverse spread. The method can be applied in structure design at other wavelengths, and it is meaningful for designing broadband anastigmatic optical systems.

The large angle deflection of light causes such problems as the high Fresnel loss and the poor luminous intensity uniformity. To solve these problems, a design algorithm of double freeform surface lens, which is based on the optimal double deflection energy mapping and the multi-parameter optimized Bézier curve, is proposed. Guided by this algorithm, a double freeform surface lens based on the light emitting diode (LED) of chip on broad (COB) is proposed, and it can be used for the optical transmitting end of visible light communication systems. To reduce the Fresnel loss, we use the large-emission area COB LED as light source, and control the ratio of incident light deflection angles of freeform surface lens’s inner and outer surfaces. Double freeform surface lenses, with large angle uniform luminous intensity distribution and with irritation angles of 180° and 260° respectively, are constructed. The luminous intensity uniformity of the lenses reaches up to 0.92 and 0.90 respectively, and the light utilization efficiency of the lenses reaches up to 89.4% and 85.9% respectively. The optical properties of the single freeform surface lens and the double freeform surface lens are compared. For the single freeform surface lens, light distribution with high luminous intensity uniformity over 0.85 and high light utilization efficiency over 0.85 can be achieved when the irritation angle varies in the range from 120° to 180°. For the double freeform lens with the same luminous intensity uniformity and light utilization efficiency, the irritation angle varies in a broader range from 100° to 260°. This study indicates that the double freeform surface lens can realize uniform light intensity distribution with broad irritation angle, and it can satisfy the light distribution requirements of optical transmitting end in visible light communication systems.

The mechanism of Fano resonance spectrum dip resulting from the system of symmetric metallic multi-nanoparticles-thin film belonging to C3v and C4v is deduced in detail using group theory. Based on previous research achievements, it is verified that there are only four E modes meet with the same irreducible representation in the system of Cnv symmetric multi-particles-thin film, when the linearly polarized light electric field inputs along the multi-particles plane. There are only three local surface plasmon electric dipole moment resonance symmetry modes in the multi-particles plane, and among them, the periphery ring-multiparticles own two, the central particle own one. These results are completely the same with electric dipole moment distribution of Dnh symmetry multiparticles system. The direction of the electric dipolar moments of the rest one is perpendicular to the multi-particles plane although it satisfies the requirement of the same symmetry. In addition, Cnv and Dnh point groups hold the same spectrum linetype, however, there is some redshift or blueshift of spectrum dip (peak) if the thin film base exists. This work can provide some references for designing the optical properties and its extended applications about the system of metallic multi-nanoparticles-thin film.

In order to achieve near-ground and multi-wavelength space-time detection of aerosol and overcome the problem of lack of selectable laser wavelength, a new type of light-emitting diode (LED) light source radar is designed using the abundant spectral characteristics of LED. The energy of LED is low, and the divergence angle is large. The output energy, divergence angle, receiver′s field angle and geometric overlap factor will affect the detection range of LED light source radar. In this paper, aiming at the characteristics of the coaxial LED light source radar system, the features and calculation methods of the geometric overlap factor are analyzed, and the influences of light source divergence angle and receiver′s field angle on the geometric overlap factor are discussed in detail. Combined with the characteristics of the LED light source, the detection capability of the radar system is simulated by US standard atmospheric model, and the light source divergence angle and receiver′s field angle are optimized. The maximum detection range is got at the certain LED energy. The LED light source radar system is built and preliminary experimental observation is completed. The experimental results show that the designed radar can receive the atmospheric echo signal at the distance of 240 m at night. It verifies the radar′s ability to detect low-level atmospheric aerosol.

Building extraction plays an important role in building reconstruction and urban management. In this study, a normalized difference vegetation index (NDVI) constrained watershed segmentation algorithm is utilized to segment airborne LiDAR data, and certain criteria are used to discriminate building regions as follows. First, grid data is attained by the interpolation of LiDAR point clouds. Then, the NDVI constrained watershed segmentation algorithm is applied to segmenting the digital surface model data, which is generated from LiDAR. Further, NDVI is introduced in the flooding process of the watershed algorithm to separate the vegetation from the buildings. Finally, the building regions are identified through some of the criteria (elevation difference, size, and NDVI) according to the adjacency relationship of each region. The benchmark data of the International Society for Photogrammetry and Remote Sensing for Vaihingen are used to evaluate the building detection results. The average completeness, correctness, and quality are respectively 89.2%, 94.3%, and 84.7% at the pixel level and 81.8%, 93.1%, and 76.9% respectively at the object level. Moreover, for an object with area larger than 50 m2, the average completeness, correctness, and quality are 99.1%, 100%, and 99.1%, respectively.

Two hyperspectral image classification algorithms based on Gabor features and locality-preserving dimensionality reduction are proposed. The Gabor transform is studied and implemented to extract features for hyperspectral image in the principal component analysis-projected domain. To protect locality information of neighbor features, locality Fisher discriminant analysis or locality-preserving non-negative matrix factorization is employed to reduce the dimensionality of Gabor-based feature space. The Gaussian mixture model classifier is used for classification results. Experimental results obtained from two hyperspectral datasets show that the proposed algorithms not only extract spectral-spatial features effectively, but also preserve local-feature information and multi-model structure of hyperspectral image. Compared with several existing algorithms, the proposed algorithms can obtain high classification accuracy and Kappa coefficient, and has strong robustness in Gaussian noise environment.