An inducible human eye accommodation fundus camera based on adaptive optics (AO) is designed, including diopter adjustment system, illumination system and the AO imaging system. By setting a target, the diopter adjustment system induces human eye accommodation and corrects primary aberration to make the residual aberration in the range of correction of AO imaging system. To eliminate the strong stray light caused by a cornea and to illuminate the eyeground uniformly, double-axicon is used to generate annular beam that the inner diameter can be changed continuously by adjusting the distance between axicon-lens to accommodate different eyes. Hartmann-Shack wavefront sensor is used as wavefront detector and deformable is used as mirror as the wavefront corrector in the AO imaging system. Simulation results show that the illumination uniformity at the fundus is up to 95%，and the modulation transfer function of every field is greater than 0.36 at cut-off frequency of 76 lp/mm with the distortion less than 1%. The system design meets the requirement and can image eyeground clearly on the condition that diopter ranges from -6D to +8D.

Cirrus clouds have an important effect on the radiation balance between the earth′s surface and the atmosphere. The properties such as cloud structure and optical depth of cirrus clouds are investigated and the detectivity of different wavelengths to cirrus clouds is analysed by using observations obtained from the three-wavelength lidar system in Hefei for the period from January 2011 to October 2012. The results show that the lidar with longer wavelength among 355, 532, 1064 nm has the better detectivity for cirrus. The peak height of cirrus clouds over Hefei is lower in winter and higher in summer with a mean value of about 8 km; and the average cloud thickness ranges from 1 km to 2 km. The cirrus optical thicknesses detected by the three different wavelengths are nearly the same, conforming that the extinction coefficient of cirrus cloud is independent of the wavelength. Most of the cirrus clouds over Hefei are thin cirrus clouds whose optical thicknesses are less than 0.3, and the mean values are about 0.12.

Traditional laser guide star (LGS) is difficult to detect the variance of atmospheric tilt because of the limitation of laser transmitter and receiver light path. An important solution is to use auxiliary telescopes to detect the LGS from the side, in order to single out the information of atmospheric tilt from the observed LGS strip. It leads to the phenomenon of anisophanatism with the increase of the length of LGS strip. The Zernike coefficient correlations between two spherical waves coming from the LGS strip are developed. From the point of correlation, the effect of the altitude of LGS, atmospherical turbulence and the caliber of the receiving telescope on the anisoplanatism of the LGS strip is analyzed. Furthermore, based on the anisoplanatism limitation of the tip-tilt determination concept, the request of field of view (FOV) of auxiliary telescope to view the sodium LGS is presented.

Based on the virtual temperature, wind speed and H2O concentration data respectively measured by the sonic anemometer and Li7500 CO2/H2O analyzer sensor in the summer of Hefei, the effects of humidity fluctuation on the measurement of the refractive index structure parameter C2n for visible radiation by sonic anemometer from two aspects are studied. The real temperature from virtual temperature via humidity corrections is obtained. Temperature structure parameter C2T respectively calculated via real temperature and virtual temperature is compared. In the other side, the contributions of humidity structure parameter C2q and temperature-humidity correction CTq on C2n are calculated. The results show that the distinction between C2T calculated via real temperature and virtual temperature is obvious, and the difference is more than 10% most of the time. The contribution of CTq can be more than 10%, and it can′t be ignored. The contribution of C2q is extraordinarily small, lower than 5%, and it can be ignored.

A novel scheme based on light diffraction to generate a triple-well optical trap for trapping and controlling triple-species samples of cold atoms or molecules is proposed. Specialized phase modulation similar to binary phase-grating is implemented by a diffraction device of liquid crystal spatial light modulator (LC-SLM). A continuous and reversible evolution between single-well trap and triple-well trap is investigated. Corresponding experiments are performed and the results are in agreement with theories. The results show that the proposed scheme has a controllability advantage, which is beneficial to load and control triple-species samples in cold atoms or molecules experiments.

When to detect the air target at the low altitude by the infrared (IR) detecting system, the scenery on the ground can also be contained in the view of the detector, and affects detecting of the target. Based on the IR imaging, the problem of the ground scenery can weaken the detecting capability of the IR system is studied, and the reason for this problem is analyzed, the method of graying a special signal range within the view of the detector is proposed for this specific problem. According to this method, the radiation of the target and its background are evaluated, the length and the location of the signal range to be grayed are confirmed by the evaluated results, so the signal range that need to be grayed can be gotten. The calculated and experiment results show that the detecting capability can be improved by this method when encountering the ground scenery.

In order to describe and congnize the distribution of the diffraction field of axicon completely, according to the theory of asymptotic expansion, the diffraction integral function with large number and non-stationary end-point in integral domain is processed, the approximate analytical solution of intensity distribution in the shadow paraxial area of axicon is obtained, and a novel phenomenon that the distribution is Poisson diffraction spot is found. The experimental results show that the intensity distribution of diffraction spot follows zeroth-order Bessel function in shadow paraxial region, and the diffraction spot diameter increases linearly with the propagation distance, although its energy in longitudinal section has attenuation along with propagation. The illuminated beam and Poisson diffraction spot never overlap for both of their diameters increase linearly with propagation distance, so in theory this Poisson diffraction spot can be propagated to infinity. Compared with common methods, which through circular screen to generate Poisson diffraction spot, axicon provides a new convenient way for the production of Poisson diffraction spot in large-scale space.

To enlarge the steering range of optical phased array, volume holographic grating is employed to act as amplifier stage. The influence of structure parameters and fabrication errors on the performance of grating is studied, and tolerance optimization is proposed to reduce the influence. The results show that grating thickness and refractive index modulation are main parameters that affect diffraction efficiency; grating period and thickness are main parameters that affect angular selectivity. Bragg angle and diffraction angle are determined by grating period and grating vector slant angle, which can be adjusted by rotating medium in the incident and diffraction plane if the angular magnification keeps unchanged. In fabrication process, grating period error and grating vector slant angle error will make diffraction angle diverging design value. The longer readout beam wavelength is, the less impact grating period error has; the higher medium refractive index behind grating is, the less impact grating vector slant angle error has. Increasing grating thickness design value can reduce the impact of grating thickness error on diffraction efficiency, while reducing grating thickness design value can reduce the impact of refractive index modulation error on diffraction efficiency, so it′s necessary to combine with the optical phased array system′s requirements to make integrated design.

Measured interference fringe period error has a major effect on the phase stitching error in scanning beam interference lithography system. In order to make high quality grating masks which can meet the requirement of the ion beam etching, mathematical model of the relationship between measured fringe period error and dose contrast is established. Based on the photoresist nonlinearities in developing process, the developing model of grating masks made by scanning beam interference lithography system is built. According to this model, variation of groove profile with measured fringe period error is given. Experiments are done to verify this model. It shows that: measured fringe period error makes groove profile worse and varies in space domain. With a certain measured fringe period error, phase stitching error between scans is proportional to step over distance and inversely proportional to fringe period. When interference beam waist radius is 1 mm, step over distance is 0.8 mm and grating line density is 1800 gr/mm, with certain developing conditions, measured fringe period error must be less than 139 ppm to make grating masks with bottom clean without residue and groove uniform.

For dual-tapered fibers with non-absorbing refractive index, the mode-coupling equation for dual-tapered fiber coupler is derived, and the relationship among cross-coupling coefficients, self-coupling coefficients, interference-coupling coefficients and propagation constants is deduced by using the conjugated reciprocity theorem. Based on this relationship, the approximate solution to mode-coupling equation of dual-tapered fiber coupler with the identical propagation constant is solved. The analytical expression for the coupling optical power is obtained. Impacts of these coupling coefficients on the coupling optical power are discussed.

A dual-loop optoelectronic oscillator (OEO) with reciprocating optical path is presented. The utilization ratio of delay for a fiber can be doubled due to feedback modulation after the optical signal passed through the Mach-Zehnder modulator (MZM) twice. And two optical loops with different lengths can be formed in the same way. This mechanism is based on the theoretical analysis of the oscillate condition and mode selection principle of the dual-loop configuration about this dual-loop configuration is analyzed. Furthermore, compared with the conventional optoelectronic oscillator, the experimental results show that such dual-loop configuration can effectively improve the side-mode suppression ratio and the side-mode suppression ratio is 48.33 dB, the single side band phase noise is -97.35 dBc/Hz at 10 kHz of frequency offset. In addition, the consumption of fibers can be reduced and the control parameters are sampled since no extra active devices in this dual-loop OEO are needed. The random interference and beat noise can be eliminated when the signal in the two loops transmits in opposite direction.

The transmission rate of the commercial light emitting diode is limited by modulation bandwidth in visible light communication. While there are more than one light emitting diode (LED) wicks in a lamp, so a high-speed transmission system scheme that the multi-LED wicks transmit data in a single lamp simultaneously, which utilizes the interleave-division multiple-access technology to superimpose mode in parallel and uses a single photodiode to receive data, is designed. As the driving voltage of LED is non-negative and photoelectric detector (PD) only detects the light intensity information, the transmitter structure, the receiver detection algorithm of multi-LED wicks and the decoding algorithm of repetition code based on single carrier on-off keying (OOK) modulation are proposed. And the signal noise ratio (SNR) performance evaluation algorithm based on OOK modulation is researched. Finally, compared with the multi-carrier direct current (DC)-biased optical orthogonal frequency division multiplexing under the same conditions in the simulation, the proposed scheme is more superior in the performance of anti-nonlinearity and bit error ratio (BER).

A novel method with a single gradient index (GRIN) lens for 1×N fiber coupling is proposed. A calculation and design method is founded to calculate beam focus position when a pointolite is illuminating an angular surface of a GRIN lens. In coupling module, the GRIN lens has one polyhedral end which is taken as the input port to split input light into several beams, and split beams get focused through GRIN lens. Beam focus position can be adjusted by some system parameters. These beams get focused through the GRIN lens, and couple into output fibers and fiber cores separately, meanwhile aberration is corrected. The simulation results show that the coupling models in different applying situations have high coupling efficiency by optimizing some key parameters, e.g. tilt angle of surfaces and object distance. It can be proved that the coupling method is simple in structure and easy to assemble. It provides a practical coupling method for variety of photonic crystal fibers, multi-core fibers, fiber bundle and fiber combining.

Based on the coupled-mode theory, the mode transition in long-period fiber grating (LPFG) coated with double-layer overlays including metal film and refractive response characteristics of overlay thickness have been studied. According to the excitation condition of surface plasmon resonance (SPR) and the occurrence condition of the mode transition, it is pointed out that its SPR and the mode transition do not occur at the same time, based on which, the changes of the efficient index of LPFG coated with double-layer overlays including metal film with sensing film thickness are analyzed, and it is obtained the mode transition zone of LPFG coated with double-layer overlays including metal film is wider than that of coated LPFG, and the slope of the efficient index of the first transition in the mode transition zone is bigger than that of coated LPFG, which means that there are higher responses for the variations of the sensing film thickness in this zone. The influences of metal film thickness on the refractive index of LPFG coated with double-layer overlays including metal film are further investigated. The result shows that the slope of efficient index increases gradually with the increase of the metal film thickness in the first transition of the first mode transition zone. The response characteristics of transmission spectrum of LPFG coated with double-layer overlays including metal film with sensing film refractive index in the first mode transition are investigated. The results indicate that sensitivity of sensing film refractive index of LPFG coated with double-layer overlays including metal film is higher than that of coated LPFG, and the resolution of the sensitivity of sensing film refractive index can be 10-6.

In order to achieve a stable, isochronous and synchronous multi-coupled chaos communication, a bidirectional chaos communication system and a multi-coupled chaos synchronization model using optoelectronic feedback delay are proposed. The time delay and chaos modulation encryption technology are introduced to increase the security of the system. The synchronization characteristics, safety performances and communication performances of the system are numerically analyzed. The results show that the stable isochronous synchronization can be observed after a very short time. What′s more, the changes of the delay time, powers of information signals, powers of laser optical signals and phases have not bad influences on the system qualities, namely these parameters can be used as keys to improve the security of the system. The proposed bidirectional communication system can be extended to a multi-coupled communication system which meets a certain topological structure, and we speculate that with the increase of the dots in network, the complexity of the system increases.

The existence of phase errors severely decreases the imaging quality of optical synthetic aperture system. The quantified scales are designed for the various characteristics of piston error and tip/tilt error. Moreover, Wiener filter and correlation coefficient are opted as restoration and assessment method. Statistic results demonstrate the value of correlation coefficient can be guaranteed beyond 0.98 on condition that average piston error is less than 0.06λ and average tip/tilt error is less than 16 μrad. Furthermore, the method of rotating the array and acquiring multiple images with various spectra is utilized to reduce or eliminate the effects of phase errors. An optimized scheme is brought out by comparing the restoration results of various rotation angles and times. The experimental result shows that the proposed method can dramatically increase the restoration quality of imaging system with phase errors. The phase error tolerances can be improved to 0.12λ and 35 μrad, respectively, which means the precision demand of optical design and phase error correction is decreased.

To improve the concentrate efficiency of the parabolic trough concentrator, the measurement and adjustment of overall surface are needed. The theoretical overlay photographic method is used to measure the installation position and tilt angle of facet mirrors, and then the concentrator surface information is obtained. It can calculate the theoretical shape and position of the receiver in image by measuring the relative position of concentrator and cameras, while the theory position formula of receiver is deduced in concentrator. The experiment of the theoretical overlay photographic method measuring the concentrator surface is done. This method can match the actual position of receiver to theoretical position in image by adjusting installation position of facet mirrors, which verifies the feasibility and correctness of this method.

As a precise optical frequency ruler, femtosecond optical frequency comb can be used to generate continuous-wave laser with ultrahigh frequency stability. Absolute distance measurement by multi-wavelength interferometry, making use of multiple wavelengths referenced to comb modes, has advantages of fast measuring speed, real time, large non-ambiguity range and high precision. Based on the theory of multi-wavelength interferometry and high frequency stability of optical comb, the second-order synthetic wavelength method is proposed to extend the non-ambiguity range and keep an enough wavelength gap for the wavelength demultiplexing of interference signals. Combined with characteristics of wavelengths in the optical comb, relationship between non-ambiguity range and wavelengths is analyzed, and selection procedure is elaborated. Simulation is performed with a fractional coincidence demodulation algorithm. The result shows that four wavelengths interferometry can achieve a non-ambiguity range of 35.636 mm with fractional phase accuracy of 0.01, and in the case of five wavelengths that range can be up to several hundred millimeters. The latter range corresponds to a dynamic range of 109 level, relative to measurement resolution.

Three-stage Mueller matrices measurement by polarization state modulators is presented theoretically, and the method is verified by experiment. Through the establishment of system equations, the Mueller matrices of optical device under test can be solved by least squares algorithm. The scheme which is based on system estimation theory is different from the method of measuring the input/output states of polarization with an in-line polarization state analyzer. The Mueller matrices and physical polarization parameters can be obtained in just one experiment. The standard deviations of measured retardances of optical components are 0.0012, 0.0018 and 0.0040, respectively. In addition, the simulation of uncertainty and the error accumulation of the system are discussed in detail. There is error accumulation effect in the cascaded system, and the result is consistent with the experimental data.

Polarizing beam splitter cube (PBSC) is the core of the polarization measurement system. The machining and assembly error of the optics component directly affects the polarimetric detection deviation. By analyzing the interaction between the incident light and the optics component, the ratio of the partially polarizing beam splitter cube is deduced, and the result theoretically shows that the best ratio is 78.9/21.1. The detection deviation of PBSC is presented with the change of the incident light polarization angle. The effect of half-wave plate (HWP) and quarter-wave plate (QWP) assembly angle deviation is included when splitting ratio deviation is ±2%. It theoretically indicates that to meet the polarization detection deviation less than 2%, the ratio deviation of PBSC should be less than ±0.5% and the HWP assembly angle deviation within ±0.5°. The effect of QWP on the detection deviation can be strongly ignored when the assembly angle deviation is within ±2°.

A compact arrayed waveguide grating (AWG) triplexer based on SU-8 strip waveguides is designed and realized. The cross-order design method utilizing the spectral periodicity of AWG don′t need to change the layout of AWG, and there is no need of extra component to cover all three operating wavelengths of 1310 nm, 1490 nm and 1550 nm for the triplexer. The core layer is SU-8 polymer, the under-cladding is SiO2, and the upper-cladding is air. The AWG triplexer can be easily fabricated by using direct ultraviolet photolithography process without additional etching process. The simulation results show that the 3 dB bandwidth of three working channels are all larger than 11 nm, and the polarization dependence wavelength shift is less than 0.65 nm. Experimental results verify the cross-order design. For transverse magnetic (TM) polarization, the excess loss of the second and the third wavelength channel is about 3 dB, which is about 7 dB for the first. The crosstalk is better than -15 dB. The whole device has a compact size of as small as 1.3 mm×0.402 mm.

Tunable fiber lasers are widely applied in fiber communication, optical fiber sensing, laser spectroscopy, precision measurement and laser processing etc. Considering of the deficiencies of current tunable lasers in tuning, flexibility, stability and multi-wavelength power equalization, a novel C-band tunable multi-channel fiber laser based on a digital micromirror device (DMD) is proposed. This tunable laser uses erbium-doped fibers as the laser gain medium and an opto-DMD processor as a tuner to dynamically select arbitrary lasing wavelength. The laser has three tunable output channels in 1530~1560 nm with resolution of 0.055 nm/pixel, and each channel can be controlled independently. The side mode suppression ratio of laser signals is greater than 55 dB. The maximum laser output power is about 10 mW and the fluctuation of the center wavelength within 2 h is below 0.02 nm.

Speckle suppression is a technical bottleneck hampering the development of laser display technology. The effects of the scattering angle of the diffuser, the number of cascade diffusers and the separations between them on the width of the scattering beam coherence area are analyzed by the experiments. On the base of the scatterer composed of cascade diffusers and lightpipe, the laser decoherence phenomena achieved by applying cascade diffusers is explained according to the multiple scattering theory. Based on statistics of integrated speckle, the relationship between the autocovariance function of the intensity and the speckle contrast is derived from the speckle pattern within the integration time T of CCD, and the influence of cascade diffusers on the displacement of the moving diffuser is determined, which contributes speckle suppression. The experimental results show that the combination of the scatterer with the moving diffuser not only improves optical energy utilization, but also reduces the speckle contrast from 0.753 to 0.069 within the integration time 1/30 s of the detector.

Due to the significant fluctuation and the real-time measurement difficulty of residual stress, a finite element model of laser shock peening (LSP) on residual stress field of Al alloy welding has been developed in ABAQUS. The residual stress fields of 7075-T6 Al alloy welding are computed and compared before and after LSP, and special attentions are paid to the effects of LSP on residual stress field of 7075-T6 Al alloy welding. Subsequently, the processing parameters of LSP on Al alloy welding are also optimized. Results show that LSP causes the residual stress evolution from tensile residual stress to high-level compressive residual stress on the Al alloy surface. Residual stress distributions can be clearly improved by optimizing the processing parameters (including laser pulse energy, spot size and overlapping rate). When the overlapping rate is between 50% and 70%, residual stress tends to a more uniform residual stress field, which can effectively eliminate “residual stress hole”.

In order to extract center and radius of target in the image, a method based on global information of target is proposed. Hough Transform (HT) for circle detection is provided as a preprocessing procedure for target detection, results of HT are used as reference for segmenting the region for target parameters determination. Region contains target found by HT is called region of interest (ROI), and square regions on the target and centroids of square regions are extracted in further step. Centroids of square regions are used to fit circle for determination of precise position of center and radius of target. According to center and radius of target, other regions on the target are detected, and parameters of these regions are deduced. Correspondences between parameters extracted from the image and model target are calculated. Experiments operated in laboratory show that position precision of centroids of regions in ROI is 0.09 pixel, and experiments outside of laboratory show that the precision is 0.12 pixel. Complexity is simplified and position precision is improved in accordance to previous image when sequence images are under processing.

A monocular vision based three dimensional (3D) dense scene reconstruction technique is presented to achieve fast and accurate 3D stereoscopic modeling in the real environment. This proposed approach localizes accurately a free moving camera in the framework of parallel tracking and mapping (PTAM) algorithm. Based on this self-localization, a variational depth map estimation model is established by using a bundle of image around the keyframe. Discrete depth space sampling strategy is proposed to initialize the variational depth map model and primal dual algorithm is presented to optimize the model afterward. Subsequently, the final 3D scene model can be estimated by integrating the projective camera imaging model. Under the compute unified device architecture (CUDA), the algorithm is optimized in parallel mode by using the graphic processing unit (GPU) hardware, and its real-time performance is significantly improved. The experimental results conducted in realistic scenario demonstrats the feasibility and effectiveness of the proposed algorithm.

Occlusion is a major problem in dynamic space intersection measurement with multi-camera systems. When occlusion occurs in measuring process, certain control points can only be observed by one camera, so the typical method of space intersection can′t be useable. To process the occlusion problem, the locations of the control points can be roughly determined, the optimal results can be obtained through iterative optimization algorithms, and the objective function can be established by multi-plane constraints of the available control points (the points are observed not only by all the cameras, but also by parts of the cameras). The experimental results show that the method can solve the occlusion problem well, and provide reliable measuring accuracy at the same time.

Magnetorheological(MR) fluids are a kind of dispersion system. Through the study on the stability of dispersed system and the actual needs of magnetorheological finishing (MRF), the components of a water-based MR polishing fluids are determined, which are suitable for optical manufacturing in this paper. The initial viscosity of the MR polishing fluids is only 0.2 Pa·s. The yield shear stress of this MR fluid is 42.5 kPa via magnetic rheometer test under the shear rate of 1 s-1 and magnetic field intensity of 0.35 T. Polishing experiments are carried out on K9 glass and silicon with the MR polishing fluids. The experimental results show that the relative changes of removal function peak removal rate are 0.15% and 0.22%, and volume removal rate are 1% and 0.88% for K9 glass and silicon respectively in 2 h continuous polishing. The peak removal rate of removal function reaches 4.83 μm/min for K9 glass and 1.376 μm/min for silicon. The results prove that the MR polishing fluids has a good stability and high removal efficiency which ensure that the polished material will be fast removed and has convergent efficiently by MRF.

Based on the first principles pseudo-potential plane-wave method, geometrical structure, electronic structure, and optical properties of V-Al co-doped CrSi2 are calculated. The photoelectric properties of un-doped CrSi2, and co-doped with V and Al, and single-doped with V or Al are compared in detail. The results show that: co-doped with V and Al, the lattice constant a, b, and the volume of CrSi2 is increased. V-Al: CrSi2 is a p-type indirect semiconductor, and the energy gap is 0.256 eV, which is between the gap value of CrSi2 with single-doping V or Al. The density of states near the Fermi energy is mainly composed of Cr-3d, V-3d, Si-3p and Al-3p orbital hybridization. Compared with pure CrSi2, the static dielectric constant and the refractive index of CrSi2 are increased with co-doping of V and Al. A new transition peak of εi(ω) is appeared at the lower energy region. Near 5 eV, the transition peak intensity of εi(ω), the absorption coefficient, and the photoconductivity is decreased, respectively. The absorption edge generates a red shift, and the average reflection effect is decreased. Doping with V will weaken the electron transition in Al single-doped CrSi2. V-Al co-doped can critically regulate the band structure and the optical properties of CrSi2.

Millimeter wave communication has been a focal point of research currently and become more and more attractive. A dual-band left-handed material structure is proposed for the application of millimeter wave communication. The structure cell is composed of two S-shaped conductor planes with upper and lower asymmetric rings, which are printed reverse of each other on both sides of the dielectric substrate. Through choosing and optimizing the structural dimensions reasonably, the S parameter values with two transmission peaks at about 50 GHz and 60 GHz are obtained. The corresponding electromagnetic parameters are calculated by the S parameters inversion algorithm. Simulated results demonstrate that permittivity and permeability are simultaneously negative from 48.2~52.2 GHz and 58.7~60.8 GHz where the typical left-handed characteristic is shown. The research has certain reference significance for the design of multi-band left-handed material and millimeter wave communication application.

Pr3+-doped cadmium tungstate yellow-green phosphors Ca1-xWO4xPr3+ (mole fraction x=0.1%, 0.3%, 0.5%, 0.7%) are successfully synthesized by the co-precipitation method. The crystal structure, morphology and photoluminescence (PL) properties are characterized by X-ray diffraction (XRD), scanning electron microscope (SEM) and fluorescence spectrometer. The results show that CaWO4:Pr3+ has a tetragonal sheelite structure with space group I41/a. The SEM image shows that the grains are irregular with sizes ranging from 5 to 20 μm. The emission spectrum of the CaWO4:Pr3+ phosphor is characterized, its peaks locate at 530, 547，555, 602, 618, 637 and 648nm corresponding to the 3P1→3H5, 3P0→3H5, 3P0→3H5, 1D2→3H4, 3P0→3H6, 3P0→3H6 and 3P0→3F2 transitions of Pr3+, respectively. The strongest one appears at 648 nm when is excited by 487 nm which matches well with blue chips. The optimized concentration of Pr3+ is 0.5% for the highest PL emission intensity. In addition, to understand the fluorescent spectra of as-synthesized phosphors, a complete 91×91 energy matrix is built by an effective operator Hamiltonian including free ion and crystal field interactions. The fluorescent spectra for Pr3+ ion at the tetragonal (S4) Ca2+ site of CaWO4 crystal are calculated from a full diagonalization (of energy matrix) method. The fitting values are in good agreement with the experimental data.

A comparative studies on the morphology of micro/nano-structure, the thickness of nacreous layer of natural-color golden seawater cultured pearl with different diameters and golden shades are carried out by ultra-violet and visible (UV-Vis) absorption spectrum, scanning electron microscopy (SEM) and high resolution transmission electronmicroscopy (HR-TEM). Furthermore, the relations between the thickness of nacreous layer and the color and the unique characteristic of UV-Vis spectra are further discussed. The results show that: the intensity of absorption band in UV-Vis absorption spectra is increasing as the deep color of golden-color pearl, the deep or light color of golden-color pearl has no direct relation with the thickness of nacreous layer. It is found that the thickness of nacreous layer located in different regions on the surface of golden-color pearl is different. Meanwhile, the density of “imbricate” structure and the morphology of the surface of golden-color pearl are different. The above characteristics maybe result to the slight varied UV-Vis absorption spectra with different regions on the surface of nacreous layer. In addition, one dimensional quasi-photonic bad gap structure exists in the nacreous layer of golden-color pearl, which should have close relations with the coloring of golden pearl and the density of golden-color.

Tm,Ho:LuAG crystal with high optical quality is grown successfully by the Czochralski method, and its spectroscopic characteristics are investigated. The absorption spectrum of Tm,Ho:LuAG crystal in the range of 320~3000 nm is measured, and a wide absorption band with full width at half maximum (FWHM) of 12 nm is located near 784 nm. The fluorescence spectrum in the range of 2800~3000 nm is measured by exciting with 784 nm laser diode (LD). The fluorescence decay curves are also measured by exciting with optical parameter oscillation (OPO) laser. The lifetimes of the upper lever 5I6 (51 μs) and lower lever 5I7 (7.5 ms) are obtained by fitting the exponential decay curves. Compared with the parameters of Tm,HoYAG (Y3Al5O12) crystal, it suggests that Tm,Ho:LuAG crystal is a potential mid-infrared laser material to realize the laser at 2.911 μm.

With the wide application of broadband imaging spectrometer in the ocean remote sensor, the depolarizer in front of the optical system must satisfy the high requirement. Based on the theory of matrix optics, Lyot depolarizer is introduced. According to the numerical analysis, the relationship between the residual polarization and the angle and thickness of the depolarizer is analyzed in the wide wavelength range. Combined with the residual polarization and resolution requirement of the optical system, a depolarizer used in a broadband imaging spectrometer is designed. With in the wavelength from 400 nm to 950 nm, when the spectral resolution is 4 nm, the residual polarizations of the depolarizer are less than 2% for arbitrary polarization of linear polarized.

When fabricating ultra-large aperture mirrors, it′s always very crucial to reduce the control difficulty and to lower the cost of the support system while providing the support accuracy required for on-line fabrication and testing. For this purpose, layout optimization method of supporting points for the equal-force support system is proposed. Firstly through surface fitting, surface figure accuracy of supported mirror is analyzed, and the objectives for layout optimization are auto-updated. Afterward support layout optimization, whose model has the capability of adaptive finite element analysis, of arbitrary-shaped thin flat mirrors is carried out. Sequentially load transfer structure for lightweight mirrors, which are widely used, is designed and the support location within each transfer is optimized. Finally the optimization method is applied to 30 m telescope (TMT) tertiary mirror and a 2-m aperture mirror. Results show that the proposed method has the required accuracy for the optical fabrication of ultra-large mirrors.

In order to evaluate surface of large aperture reflecting mirror, the Randon transformation is used to represent the area structural function collapse. The evaluation ways of algorithm for collapse are studied, and the specific step is expressed. Then this method is applied to the Zernike polynomial which can simulate the wave front perfectly. The algorithm is applied to the meter rank reflecting mirror and tertiary mirror of 30 m telescope (TMT) simulating data, the correctness and feasibility of the algorithm are certified. This research will supply good instructions at the design, measurement and manufacture of large mirrors, and will do good to the complement of tertiary mirror of 30 m telescope.

Acousto-optic tunable filter has many merits such as, wide spectrum range, rapid tuning large aperture angle and narrow band pass and etc.. In this work, the authors design a noncolliner acousto-optic tunable filter considering the rotatory property of TeO2. Moreover, we evaluate the performance of the acousto-optic tunable filter theoretically and experimentally and the experimental results are in accordance with the theoretical expect. Also, this filter is used in hyperspectral microscopic imaging system combining with inverse optical microscope system and it is capable of detecting and mapping material with different ingredient monochromatically.

One kind of terahertz resonator consisting of split-ring resonator (SR) and cut wires (CW), which has electromagnetically induced transparency (EIT), is studied theoretically and experimentally. The transmission characteristics of the resonators containing one or two gaps for the split ring are numerically simulated, and the impact of the relative position of the split ring on their resonant peaks intensity and Q-factor are analyzed. The resonant peaks of EIT spectra of SR/CW resonators are found around 0.7 THz due to destructive interference between the LC resonance of the split-ring resonator and the dipole resonance of the cut wires. Both the amplitude and Q-factor of the EIT resonance are very sensitive to the position shift of the split ring for the SR/CW resonator with one gap, and are insensitive for the two gaps. Finally, the SR/CW resonators are fabricated on polyimide substrate using laser-induced and chemical non-electrolytic plating with copper, the transmission properties of which characterized by THz time domain spectroscopy are in good agreement with simulations.

Based on the Fresnel diffraction integral and Laguerre-Gaussian beam field distribution, the circular aperture diffraction, single slit diffraction and square hole diffraction of Laguerre-Gaussian beam are studied, and the effect of spiral phase structure on the field distribution of the diffracted light beam is analyzed as well. The degree of dispersion of the orbital angular momentum is also calculated using the well-known spiral spectrum, when Laguerre-Gaussian beam passes through a single slit or a square hole in the same case of Laguerre-Gaussian beam phase singularity locating at the center of a diffraction hole. According to the theoretical calculation results, it′s demonstrated that the orbital angular momentum does not disperse when Laguerre-Gaussian beam passes through a circular aperture.

The entanglement properties of three-color and tripartite entangled state produced from two cascaded type I second-harmonic generation cavities are analysed. It is shown that the reflected pump beam of the first cavity, the reflected pump beam and the output second-harmonic beam of the second cavity are entangled, and the dependence of the entanglement degree on various experimental parameters is also analyzed. The scheme provides a reference for generation of multicolor entangled state and its application in quantum measurement and quantum communication.

An optical stress sensor is proposed and demonstrated in experiment based on single bismuth germanate (BGO) crystal and electrooptic compensation. The sensing principle is mainly based on the mutual compensation property between photoelastic birefringence and electrooptic birefringence existing in the BGO crystal. According to the index ellipsoid analysis method, when external stress and electric field are simultaneously applied to the (111) crystalline surface, photoelastic birefringence of the BGO crystal can be compensated by its electrooptic birefringence, thus it is possible to perform the closed-loop measurement of external stress by the method of electrooptic compensation. The proposed optical stress-sensing unit is only composed of two prism polarizers and single parallelogramic BGO crystal. Additional quarter waveplate is not needed for the proposed stress sensor since the optical phase bias of 0.5π is produced by two times of total inner reflection of light wave in the BGO crystal itself. Compression stress is measured in the range of 30 kPa and experimental data demonstrated a good linear relationship between compensating voltage and measurand stress. The compensating voltage is about 4.26 V corresponding to the applied stress of 1 kPa.

A novel fiber Fabry-Perot pressure sensor is presented, which is fabricated by photoetching, silicon etching, anodic bonding and other micro-electromechanical system technologies. It is suitable for micro-pressure measurement in harsh environments and confined spaces. The structure of the sensor and the production methods are elaborated. In this structure, with the help of fiber flange, the end face of fiber can be in parallel with sensitive membrane, thus a high quality Fabry-Perot interferometer cavity is formed. The structure is also conducive to the stability of the initial cavity length, reducing the sensor′s error. The demodulation system for the testing of pressure characteristics and temperature property is set up. Experimental results demonstrate that a high linear response in the range of 0 to 0.1 MPa is obtained in this sensor. The repeatability is good and the sensitivity reaches 61.6 μm/MPa.

The optical emission spectra are measured during the positive half cycle in a sinusoidal driven needle to plate dielectric barrier discharge in argon andair, and the spatial distributions from needle to plate in the discharge channel of plasma luminous intensity, spectrum width and electric field intensity are investigated. The effect of the dielectric plate on the plasma parameters is also analyzed. According to the intensities of two lines of 763 nm and 772 nm of argon discharge specrtrum, it is found that the intensity from needle to plate increases first and then decreases around the neadle, while it increases rapidly around the plate. The distribution of spectrum width (696.54 nm) is investigated, and the spectrum width increases to maximum around the plate. The distribution of electric field is obtained by calculating the intensity ratio of the nitrogen molecular ion line of 391.4 nm to nitrogen molecular line of 394 nm in air discharge spectrum, the electric field strength decreases first and then increases along the discharge channel. The results show that the dielectric plate playes an important role in the distribution of plasma parameter.

According to the characteristics of supper-resolution, spatial interference and narrow bandwidth of spatial heterodyne spectrometer (SHS), the principle and requirement of calibration are analyzed, the methods of spectral calibration using tunable uniform planar radiances and the radiometric calibration with sphere are presented, the calibration systems are built, the spectral and radiometric calibrations of the spectrometer are fulfilled, and the calibration uncertainty is analyzed. The spectral calibration uncertainty is 0.015 cm-1, and the radiometric calibration uncertainty is 4.02%. The calibration uncertainty meets the given requirements. The calibration results are verified by measuring the actual atmospheric CO2 absorption spectra. The results show that the positions of the absorption peaks and the radiance brightness values fit well between the measured and the simulated spectra, which provides a foundation for quantitative inversion of CO2.

Oxygen is an essential component of the engine combustion process. It is an urgent demand for aircraft inlet oxygen monitoring. Aiming at aircraft engineering requirements and application characteristics, a short-path wavelength linear scanning tunable diode laser absorption spectroscopy (TDLAS) system is designed, which complete the weak oxygen absorption signal extraction and concentration inversion combined with the second derivative spectrum algorithm based on finite impulse response (FIR) filter. Theoretical basis for the second derivative spectrum method of gas concentration inversion is deduced according to the absorption signal characteristics and the TDLAS principle. A solution based on the FIR digital filter to complete absorption signal noise filtering and second derivative spectrum extracting is proposed on this basis. Experimental results show that this scheme is simple, the detected signal to noise ratio is improved, and the detection limit is reduced. Inversion results of gas concentration are accurate and linearity is good.

The optical character of optical thin films is the basis for the design and preparation of thin films. Silicon material is an important material of high refractive index at the infrared optical thin film. The changes of refractive index and extinction coefficient of amorphous silicon optical film in different deposition temperatures are studied. The results show that the silicon film has the maximum refractive index at 200 ℃, and the extinction coefficient decreases with temperature increases.

A light trapping structure of solar cell is proposed by the theory of light scattering and guided mode resonant. The porous anodic alumina (PAA) is used as a scattering layer. The thicknesses of the model are: window layer (AZO) is 320 nm, buffer layer (In2S3) is 65 nm and absorbing layer (SnS) is 660 nm. The simulated and experimental results show that the absorption of solar cell structure can be enhanced by light scattering and guided mode resonant. The absorption is enhanced by about 3% by the light scattering structure. This design can optimize the absorption spectra of this film solar cell and improve the absorption ability of near-infrared light. The absorption at the wavelength of 950 nm is enhanced to 85%, and the solar energy is better used.

Experiments confirm that the femtosecond laser induced periodic nanogratings in a transparent material represents the novel optical properties. The scattering characteristics of nanogratings and nano-grating array are studied in detail by experiments and finite-difference time-domain (FDTD) respectively. Analysis result shows that scattering characteristics of nanogratings are sensitive to the polarization of the incident laser. For arrays of nanogratings, the scattering intensity in the laser polarization perpendicular to the nanograting is 20000 times larger than that in the laser polarization parallel to the nanograting. Morerover, the scattering intensity is dependent on the incident laser wavelength. The longer the wavelength is, the weaker the scattering intensity will be. The simulation results demonstrate that type II waveguide and the light polarized guide mechanism of nanograting are based on scattering characteristics of nanograting instead of birefringence effect theoretically.

Femtosecond-laser-photolithography is a flexible avenue to fabricate three-dimensional photonic devices in transparent materials. Terbium gallium garnet is widely used because of its Faraday rotation. Femtosecond laser operated at 1 kHz with a central wavelength of 800 nm is used to write double line waveguide and circular depressed-cladding waveguide in terbium gallium garnet. The distributions of refractive index change are reconstructed，and propagation losses of the waveguides are measured. Only the double line waveguide shows polarization dependent optical guiding. The magneto-optic response of the waveguides is determined. The rotation of plane of polarization cannot be occurred in double line waveguide under externally applied magnetic field ascribed to the phase mismatch of transvers electric (TE) mode and transverse magnetic (TM) mode. For the circular depressed-cladding waveguide, the plane of polarization is rotated under applied magnetic field. The inscribed double line and circular depressed-cladding waveguide in terbium gallium garnet are candidates for waveguide polarizer and magneto-optic device respectively, which are valuable for integrated optics.

Femtosecond laser with repetition rate of 1 kHz, central wavelength of 800 nm and pulse width of 120 fs is used to write waveguides in Yb3+phosphate glass, then near-field modes of waveguide written by different laser parameters are measured. The refractive index changes in the written region and mode field diameter as functions of writing parameters (scanning speed and writing pulse energy) are obtained, which show the writing window of waveguide formation in Yb3+phosphate glass. The fluorescence spectra of the waveguide and the bulk material are tested and compared. Experimental results show that there is no difference in the fluorescence spectra of the waveguide and the bulk material with 20× objective lens, scanning speed of 20 μm/s and pulse energy of 1.8 μJ, the mode field diameter is 20 μm injected at 976 nm, the refractive index change is 2.7×10-4, and the fluorescence properities keep the same after femtoscecond laser effect. Stable and continuous wave (CW) Yb3+doped waveguide laser is achieved in a Fabry-Perot cavity configuration by using dichronic mirror and 2% output coupler. An output with power of 2.9 mW at a central wavelength of 1031 nm is obtained.