The return signal statistical model of differential absorption lidar (DIAL) is the basis of studying differential absorption lidar. However, the known statistical models ignored the effect of laser scintillation resulting from atmospheric turbulence on return signal. With considering effects of laser scintillation resulting from atmospheric turbulence, target reflective speckle, receiving noise and the fluctuation of transmitted power, a revised return signal statistical model of long-range DIAL is presented and the statistical characteristics of this model are analyzed. The simulation results show that laser scintillation resulting from atmospheric turbulence has an important effect on the statistical characteristics of return signal and verify this statistical model more accurate and reasonable than other known models.

Generation of supercontinuum (SC) spectrum in the dispersion-flattened decreasing fiber has been studied by utilizing total field formation in the frequency. The initial dispersion and the fiber dispersion-decreasing rate have significant effects on the SC generation. SC bandwidth changes slowly when these two parameters are within certain threshold values, while it changes drastically when they exceed such values. The results also show that convex dispersion fiber is more favorable than the linear dispersion fiber in the generation of wide SC spectrum, while concave dispersion fiber is not suitable for the generation of wide SC spectrum. A 330 nm wide SC spectrum can be generated from a DFDF fiber with optimal dispersion characteristics.

The all-optical switching characteristics of three-core nonlinear directional waveguide couplers (NLDCs) with Gaussian type and exponential type variable coupling coefficient (VCC) are presented. Their transmission features are investigated numerically. It is shown that， for the three-core VCC NLDCs, the power can switch completely between guide 1 and guide 3; however 100% power output cannot be achieved for guide 2. The switching curves of three-core NLDCs with VCC are sharper than those of their two-core counterparts with same maximum coupling coefficient. It is also shown that the sidelobes in the post-switching region, which exist in the parallel nonlinear directional couplers, can be suppressed with three-core NLDC with VCC.

Polarization mode dispersion (PMD) has been the major limiting factor for long-haul high-speed optical fiber transmission and the PMD adaptive compensation is required urgently. An experiment of two-stage adaptive compensation for polarization mode dispersion in a 40 Gb/s RZ optical time-division multiplexed (OTDM) communication system is reported. The particle swarm optimization (PSO) algorithm with the six degrees of freedom (DOF) is adopted to maximize the degree of polarization (DOP) and realizes the adaptive PMD compensation. The compensation process is completed within several hundred milliseconds. The method of Poincaré sphere (PS) is applied to measure the PMD values in the experimental fiber link. The results show that the DGD decreases from 21 ps to 1.3 ps and the second PMD descends from 266 ps2 to 43.5 ps2 in central wavelength of 1560.5 nm. The first and second order PMD are compensated together in different degree and the whole system power penalty is less than 1 dB (@BER 10-9) after PMD adaptive compensation.

High accurate state of polarization (SOP) converting, low cost, low insert loss, and simple control algorithms are vital for polarization transformers. A novel method of polarization transformations using two quarter wave plates (QWP) and a half wave plate (HWP) realizing transformation between arbitrary states of polarization (SOP) is presented in this work. A new geometry method, SOP projection plane, is developed from Poincaré sphere method. The expressions of azimuths of three wave plates are derived through SOP projection plane method in Stokes space. The experimental results show that

Experimental studies on 10 Gb/s 3R degraded data regeneration were reported. A method of preprocessing the data signals using comb-like filter was proposed in order to overcome the pattern effect in the clock recovery using injection mode-locked ring laser based on semiconductor optical amplifier (SOA). The amplitude fluctuation and timing jitter caused by the pattern effect in clock pulses were greatly reduced. Furthermore, it was also demonstrated that clock could be recovered from the badly degraded signals. The recovered optical clock from degraded signals is shown to be free of pattern. The core of optical reshaping is a decision gate featuring signal extinction ratio enhancement and noise reduction. The reshaping based on an electroabsorption modulator was also studied. With this technology all-optical 3R regeneration was achieved from 10Gb/s degraded data.

The bending characteristics of the long period fiber grating (LPFG) induced by high-frequency CO2 laser pulses in a bend insensitive fiber is reported. The experimental results show that the peak resonant amplitude of the LPFG written in a bend insensitive fiber has a higher sensitivity than that written in a standard telecommunication fiber. Furthermore, LPFG has different bending characteristics at circular orientation, i.e. the peak resonant amplitude of the LPFG is the most sensitive to bending but the resonant wavelength is insensitive at some circular orientations. Based on this finding, a gain equalizer is proposed to flat the gain of an erbium-doped fiber amplifier (EDFA) by bending directly. Such a system is shown to be a practical and simple approach to realize gain flattening of an EDFA with high precision for gain control.

The theory of optical synthetic aperture imaging system with emphasis on the characteristics of the spatial frequency is described. The cut-off spatial frequency is got higher at the cost of the mid-spatial frequency, and the sidelobes of point spread function (PSF) are higher. The image quality evaluation for diffraction-limited optical synthetic aperture imaging system is analyzed with two-point resolution and optical transmission function (OTF). The disadvantages of Rayleigh criterion, Sparrow criterion and threshold criterion are given. When the sidelobe is 0.5 times of the maximum, the imaging quality of synthetic aperture system is no better than that of the single aperture system. Based on the OTF, relations between the effective diameter of three operture system and pupil parameters including the diameter of sub-apertures and spacing parameter are analyzed. When the pupil diameter is fixed, practical cut-off spatial frequency becomes larger first, and then reduces with the augmentation of the distance between pupils.

Photoacoustic signals induced by a short pulse laser cover a wide spectral range. The spectral characteristics of absorbers with different sizes and the influence of photoacoustic signals with different spectral components on photoacoustic imaging are explored. The main frequency ranges of photoacoustic pressures of absorbers with diameters of ～cm, ～mm and hundreds of μm are about 20～300 kHz, 70 kHz～2.5 MHz and 400 kHz～20 MHz, respectively. The low spectral components of photoacoustic signals contributed to the non-boundary region of absorbers, and the high spectral components contributed to the small structure, especially, to the boundary. It is demonstrated that the ultrasonic transducers used to detect photoacoustic pressures should be designed and selected according to the frequency ranges of absorbers. When the frequency response range of transducers accords to that of absorbers, almost the whole frequency components of photoacoustic pressure can be detected. That produces good reconstructed images. A Q-switched Nd∶YAG laser operating at 532 nm was used as light source. The laser had a pulse width of 7 ns and a repetition frequency of 30 Hz, and a needle PVDF hydrophone with diameter of 1 mm was used to detect photoacoustic signals.

The transmission characteristics are analyzed, and the general formulas of the transmission functions are presented for the microring resonant wavelength multiplexer (MRRWM) with 1×N channels in terms of the coupled mode theory. Using the results of parameters optimization, the numerical modeling is performed for a polymer MRRWM around the central wavelength of 1.55 μm with the wavelength spacing of 5.6 nm and 8 vertical output channels. The computed results show that the device has an exact output spectrum, the insertion loss is small and determined mostly by the transmission loss for microrings with radius R greater than 10 μm. For the case of the amplitude coupling ratio of 0.2, the device designed possesses some excellent features including the free spectral range of 18 nm, smaller insertion loss less than 0.57 dB, lower crosstalk below -18.5 dB, 3 dB-bandwidth of 0.25 nm, and weaker background intensity of 3.8×10-4 for every output vertical channel.

A new effective index method (EIM) is introduced to reduce a two-dimensional refractive index structure to a one-dimensional one accurately. The present EIM can be implemented for arbitrarily shaped waveguides. An explicit formula is obtained for the effective refractive index profile determined by the model filed and the cross-sectional refractive index of the original structure. In order to show how the present method is carried out, a silicon-on-insulator (SOI) rib waveguide is used in a numerical example. The effective model field distribution and the effective index profile are calculated with the present EIM. The bending loss of a SOI bent waveguide is also calculated with the present and conventional EIMs respectively. The numerical results show that the present method is much more accurate than the conventional EIM.

It is always using F-P linearity cavity in double-clad fiber lasers. The cavity is composed of one dichroic mirror and fiber end Fresnel reflector (reflectivity nearly 4%). This is a defect and unstable cavity. It cannot exactly select frequency, and the linewidth of the laser is extensive. In some applications requiring wavelength strictly, this kind of laser is limited. As a rule Bragg gratings that compose a laser cavity are fabricated in a high germanosilicate host fiber and then spliced with an Yb3+-doped active fiber. Difference of parameters of the two kinds of fibers leads to additional losses of both pump and signal. A double-clad fiber Bragg grating which was fabricated in the core of Yb3+-doped double-clad fiber using the phase-mask method is reported. This kind of grating is used as the output mirror of the D-shape inner cladding Yb3+-doped double-clad fiber laser, the fiber length is 10 m and 20 m respectively. The laser operating near 1058 nm with stable and narrow-FWHM (3 dB bandwidth is 0.329 nm) is realized. The maximum output power laser is 570 mW. Finally, these experimental results are analyzed theoretically.

The characteristics of diode-side-pumped linear resonator were discussed in the stable condition of the laser resonator. Based on the analyses of the resonator, a simple linear resonator was designed, which was favorable for the modelocking with good laser mode and without astigmatism. In the experiment, the homemade semiconductor saturable absorber mirror was employed for passive mode-locking. Stable continuous-wave mode locking was achieved at 100 MHz repetition rate with 10 ps of pulse duration and the average output power was 2 W. Furthermore, the effects of the parameters of SESAM for the mode-locking were discussed.

The double-frequency process based on periodically poled heavily doped MgO∶LiNbO3 is theoretically researched. A first order quasi-phase-matching periodically poled optical micro-structure doped MgO∶LiNbO3 for second harmonic generation with 5.8～7.3 μm period(interval of 0.3 μm), 10 mm length, 10 mm width and 1 mm thickness has been successfully fabricated by applying an external field at room temperature and under ～5.5 kV/mm of the lower switching field. Controlling temperature at about 70 ℃，the experiment on the manufactured optical micro-structure using Nd∶YAG laser with wavelength of 1.064 μm as fundamental frequency is carried to validate the double frequency. About 15 mW 532 nm of quasi-continuous-wave double-frequency blue light output is obtained which is pumped by 920 mW of the fundamental power, corresponding to 1.77 %/W normalized conversion efficiency.

A mutual pulse injection-seeding scheme is developed to generate tunable dual-wavelength optical short pulses by the use of two gain-switched Fabry-Pérot (F-P) semiconductor lasers. Multimode optical short output pulse is first generated by gain switching two F-P lasers with the approximate setup; Then by using two fiber Bragg gratings (FBGs) as filters, mutual injection locking of two wavelength optical pulses between two F-P lasers is realized by tuning optical delay line (VODL2), and dual-wavelength optical short pulse with high side mode suppression ratio is obtained at the output end. Wavelength selection and tuning are achieved by adjusting two FBGs and another optical delay line (VODL1), while a constant repetition frequency of 524.6 MHz is maintained. The side mode suppression ratio of the output pulses is better than 25 dB at a wavelength-tuning range of 13.2 nm. The system is stable and convenient for wavelength tuning.

The refractive index and optical absorption of glass were studied when the BaO was substituted by 0.05, 0.10, 0.15,0.20 (mole fraction) BaF2 respectively in glass 0.20BaO-0.15Ga2O3-0.65GeO2 (mole fraction). The results show that, when fluoride was introduced into glass, the refractive index and dispersion of glass decrease, and the ultraviolet absorption edge shifts to shorter wavelength, but the IR absorption edge doesn't move obviously. The glass without fluoride contains a great deal of OH group that cause optical absorption band at 2.24 μm, 2.97 μm and 4.23 μm. In the glasses containing fluoride, the 2.24 μm absorption band disappears; while the 2.97 μm absorption band and the 4.23 μm absorption band weaken obviously. The origin of every OH absorption band was also discussed and Gaussian separations of the 2.97 μm absorption band of OH group were carried out. The weak peak at about 2.24 μm maybe come from the combination of a stretching mode and two shaking modes of H2O molecular (ν+2ρ); the absorption band at 4.23 μm is caused by the stretching vibrations of the OH groups forming strong hydrogen bond with non-bridge oxygen's (T-OH…O--T); the OH absorption band at about 2.7～3.2 μm can be attributed to the overlapping of stretching bands for the OH groups influenced by various species of hydrogen bond, which causes the asymmetric broadening of absorption band and the shifting of absorption center with OH group content.

Ordered Ni/AAO and Co/AAO nano-array composite structure are prepared via electrodeposition of the metal within the process of anodically-grown porous anodic aluminum oxide (AAO) membranes. The optical properties of the two composite are studied. The results show that the difference between the Ni/AAO and Co/AAO are very large. Although the micrograph of the Ni nano-particles and the Co nano-particles are nearly the same， as the metal composition increasesd， the absorption band-edge of the Ni/AAO composite is small red-shifted (13 nm). However， the absorption band-edge of the Co/AAO composite is strongly red-shifted (80 nm). Meanwhile， the Ni/AAO and Co/AAO composite exhibit the optical features of the semiconductor with indirect and direct band gap respectively.

Under ground simulation for the space environment of high vacuum, heat sink and low energy protons with less than 200 keV, the change in optical transmittance of JGS3 optical quartz glass was studied, and the kinetic model for the evolution of color centers in the process of radiation damage was set up. The experimental results show that radiation damage effects obviously occur on the surface layer of quartz glass under large flux and low energy proton radiation. The optical density change increases rapidly and then a saturation trend appears with further increasing absorption dose; and the appearance of saturation inflexion is advanced and its value decreases using higher radiation energy. By analyzing experimental results, a kinetic model for the evolution of color centers in quartz glass irradiated with protons is proposed, and the change in optical density can be given. The experimental results are mathematically fitting with the function deduced from the model. The mathematical fitted curve is similar to experimental ones. It is believed that the proposed kinetic model can be used in the quantitative description for the change in optical property of quartz glass with increasing absorption dose under proton radiation with low energy.

The wave-front aberration produced by atmosphere disturbing can be compensated with stimulated Brillouin scattering (SBS) phase conjugate technology. And with velocity compensated mirror, laser tracking and pointing at moving target in orbit is realized. The possibility of this method is proved by Gauss beam phase conjugating resonator theory. The principle experiment about laser tracking and pointing at moving target in orbit outdoor 1.27 km away is carried out. Moving target in track can be tracked and pointed by SBS phase conjugate technology, and energy of the laser can be concentrated to the target within a small area. The largest energy arriving target is up to 24.0 mJ.

The intrachannel cross-phase modulation (IXPM) and intrachannel four-wave mixing (IFWM) in dispersion managed quasi-linear systems is researched, and the role of the timing jitter induced by IXPM and the amplitude jitter and the ghost pulse induced by IFWM change with distance and dispersion map strength are analyzed theoretically. Then the theoretical analysis results are verified by the timing jitter, amplitude jitter and the generation of ghost pulse of a 25-1 pseudorandom binary sequence (PRBS) by using fast Fourier transform method. Finally, the stable transmission of 1600 km is verified in dispersion managed quasi-linear systems with dispersion map strength of 127 by numerical simulations. The results are important for high speed transmission based on single-mode fiber.

The characteristics of Er3+-doped phosphate glass waveguide amplifier (EDWA) are investigated. Using the overlapping factor, the rate-propagation equations of the four-level system of EDWA are simplified. With taking account of up-conversion and amplified spontaneous emission (ASE), the relation curves are obtained by numerical simulation between the gain and the parameters such as Er3+ ions concentration, pump power and waveguide length, and the theoretic results are consistent with the experimental results. Selecting suitable erbium ions concentration is the key of fabricating EDWA. Moreover, in order to improve the EDWA performance, the parameters are optimized such as pump power and waveguide length.

The analysis on the temperature stability of center wavelength for the thin film interleaver with multicavity by Takahashi model is presented. It is found that the change of optical constant caused by the interactional elastic force between the reflector thin film stack and the cavity with the temperature change is not the main reason affecting the shift of center wavelength of the device, however, the temperature coefficient of the refractive index of cavity material is the important factor. The simulated calculation showed that the total shift of the device with the temperature vibration from -40 ℃ to 85 ℃ would reach ±1 nm or so for a three-cavity thin film interleaver used in dense wavelength division multiplexer (DWDM) with 100 G channel interval.

Based on the multi beam interference principle, the intensity expression of the transmitted beam for a Gaussian beam striking obliquely through a nonparallel Fabry-Pérot interferometer has been derived. According to that, the influence of the nonparallelism in Fabry-Pérot interferometer mirrors alignment at a different tilted angle and waist radius on the transmission of a Gaussian beam has been investigated theoretically. The results show that the incident angle and the nonparallelism in Fabry-Pérot interferometer mirrors alignment have important effect on the intensity distribution, the peak intensity and the position of the peak intensity of the transmitted beam; the diffraction effect of the Gaussian beam must be considered when the waist radius of beam is small or the facet reflective index of the Fabry-Pérot interferometer mirror is large; if the wedge angle is negative, the intensity of the transmitted beam will reduce quickly to zero at the recoil position, which can be used to measure accurately the distance.

The coherent scattering of Gaussian beam by arbitrarily shaped convex dielectric object with rough surface is investigated. Based on the plane wave spectrum method, the scattered field of Gaussian beam from rough object is derived and the formula for calculating the coherent scattering cross section is obtained using the physical optics approximation and the stationary phase method. Compared with the result of plane wave, additional beam factor represents the effect of Gaussian beam, which is related to beam waist size, distance from beam waist to object center and the illuminated area on object, together with the incident or scattering angles. Finally the 1.06 μm laser beam scattering from rough sphere is numerically computed, and the influence of the beam factor, permittivity and polarization on coherent LRCS is analyzed. It is shown that the results of Gaussian beam will approach that of plane wave when the beam radius is much larger than the size of object.

High-quality c-axis oriented SBN60 thin films on MgO(001) substrates have been obtained by the sol-gel process, the transverse electrooptic coefficients r51 of the SBN60 without K-doped and K-doped (with the K+/Nb5+ molar ratio of 1/3) SBN60 thin films were measured as 37.6 pm/V and 58.5 pm/V respectively. The transverse coefficient of the SBN60 films was shown to increase with the K ions doping. Mach-Zehnder type waveguide modulators made of SBN60 thin films were designed. Electrooptic modulation has been demonstrated with the half-wave modulation voltage Vπ=16 V for SBN60 and that of Vπ=10 V for the K-doped SBN60 at 633 nm wavelength. The half-wave modulation voltage was demonstrated to be decreased with the K ion doping.

The residual stress in the SiO2 films deposited by electron beam evaporation under different conditions is measured by viewing the substrate deflection using GPI optical interferometer in different under cordition. The influences of deposition temperatures, oxygen partial pressure and aging on the The residual stress varies from -223.5 MPa to 20.4 MPa when the oxygen partial pressure increased from 3.0×10-3 Pa to 13.0×10-3 Pa, and from -150 MPa to -289 MPa when temperature increased from 190 ℃ to 350 ℃ which may be attributed to the variation of the microstructure concluding from the variation of the refractive index. An evolution of residual stress from compressive to tensile with time of sample storage in a conventional clean-room environment is measured for all evaporated SiO2 films investigated.

Superresolution technique is well known for the ability of compressing the central diffraction spot beyond the classic diffraction limit, and it has a wide application in the optical storage and the confocal imaging systems. The radial birefringent filter which consists of two parallel polarizers and a rotationally symmetric birefringent element is introduced into the superresolution technology, and with Jones calculus the pupil function of it is deduced. It is shown that with such filter transverse or axial superresolution can be realized just by changing the angle between the polarizers and the radial birefringent element. At the same time, the superresolution parameters G, Strehl ratio S and the influence of side-lobes are discussed. Advantages of such filter are that it is relatively simple to construct as it requires no phase changes with low cost. Disadvantage is its high strength of the side-lobes, but that can be suppressed by applying confocal system.

A human eye model based on anatomical data, which had been previously proposed by Hwey-Lan Liu, has been transformed into a new eye model considering the laminated structure of the lens. The anterior surface of the lens is prolate, whereas the posterior surface of the lens is oblate which is consistent with the anatomical data. A numerical program was written in C computer language to study the refractive structure of the eye and the optical characters of the model have been studied. The marginal wings appear in the longitude spherical aberration plot when the shell number is small, which means a lens with a small number of shells makes eyes a multifocal system. The result shows that eye with gradient-refractive-index-lens and that with shell-lens can get equivalent spherical aberration results.

The development of ultraviolet and soft X-ray monochromators with high performances is very important to the applications of high-brightness synchrotron radiation light source. The varied line-space plane grating monochromator by Itou is studed in detail, and it is found that its grating working curve is nearly independent of the monochromator parameters, such as entrance-arm and exit-arm lengths, and only determined by its boundary condition. The curve equation is similar to that of the SX-700's. The monochromator has both very good grating-diffraction-efficiency and high-order-suppression performances. Moreover, it is very convenient to optimize the monochromator performances and solve the problem of space conflict caused by more than one beamlines that share the same storage-ring window.