Photonic crystal fibers (PCFs) offer new possibilities of realizing highly birefringent fibers due to a higher intrinsic index difference and flexibilities of fabrication process compared to conventional fibers. A kind of highly birefringent index guiding PCF with a full vector model is analyzed theoretically. Two-fold rotational symmetry was introduced into the fiber structure by creating a regular array of air-holes of two different sizes in its cladding. The degeneracy of two orthogonal polarized-modes of the fundamental mode is removed. This creates a possibility to attain a modal birefringence of at least one order of magnitude larger than for conventional high birefringence fibers. A beat length of 0.4067 mm is obtained at the wavelength 1540 nm. The numerical results are in very good agreement with the experimental results.

A new fiber Bragg grating temperature sensor has been presented, which was made by fixing a fiber Bragg grating on a polymer substrate that has a large thermal expansion coefficient. The temperature sensitivity of this new fiber Bragg grating temperature sensor is about 82.69×10-6 /℃, which is 12.3 times of that of a nude fiber Bragg grating. The wavelengths of the light reflected from the fiber Bragg gratings were measured in the temperature range from -80 to 0 ℃. The low temperature characteristic of this new fiber Bragg grating temperature sensor was experimentally studied, and compared with that of a nude fiber Bragg grating and an Al substrate fiber Bragg grating. The temperature response characteristic of this new fiber Bragg grating temperature sensor is good.

A novel all-optical switch composed of cascaded Gaussian nonlinear directional couplers (NLDCs) and Exponential NLDCs is proposed. It is found by theoretical analysis and numerical simulation that the proposed switch possesses better switching characteristics since the proposed switch can suppress the sidelobes of the switching curves compared with conventional cascaded NLDCs and has steeper dynamic switching region where the power transmission increases from 0 to 1 than that of cascaded Gaussian NLDCs. The proposed switch is more suitable for all-optical switch than conventional cascaded NLDCs and cascaded Gaussian NLDCs. The parameters of cascaded couplers can also be adjusted to change the number of unit couplers to satisfy the certain requirements of the switching curve.

Dense wavelength division multiplexing system is a final selection as an optical communication system because of its high speed and big capacities, but the fiber nonlinear effects and polarization mode dispersion limit severely the performance of the system when signal propagates at 40 Gbit/s in a single channel. The coupled nonlinear Schrodinger equations of a single channel in dense wavelength division multiplexing system are derived, considering all factors of group velocity dispersion, self-phase modulation, cross phase modulation, four wave mixing and polarization mode dispersion, and their number results are obtained with extended Split-step Fourier Method. To analyze the impacts of the fiber nonlinear effects and polarization mode dispersion on the optical communication system, the simulated results of a 8×40 Gbit/s dense wavelength division multiplexing system are discussed under different conditions respectively at last. It is found that nonlinear effects influence dense wavelength division multiplexing system more severely than single wave-length system because of the effects of cross phase modulation and four wave mixing. The degree of impacts of polarization mode dispersion and nonlinear effects on system is related to the power of the input signal. When the average power of the input signal is below 0.1 mW, the influence of polarization mode dispersion is dominating; while it is 1 mW, the impact of nonlinear effects is worse than polarization mode dispersion. But polarization mode dispersion, which can widen pulse and is similar to the small chromatic dispersion in G.655 fiber, can mitigate the impact of nonlinear effects.

The transmission of optical signal under the effects of cross-phase modulation (XPM) and self-phase modulation (SPM) together in pump-probe wave structure is investigated in intensity modulation direct detection wavelength division multiplexing (IM-DD WDM) systems. The analytical method to determine the time-domain shape of probe wave when arbitrary wave is inputted in pump channel is confirmed. The impact of channel spacing and transmission rate on XPM is assessed. It is found that the main effect of SPM in pump channel is to increase time-domain intensity-modulation index to a certain extent. The analytical result agrees well with numerical simulation.

A novel approach for simultaneous measurement of temperature and pressure using a single fiber Bragg grating (FBG) based on reflected wave's broadened bandwidth is proposed and demonstrated. FBG is affixed on the non??uniformity strain area of double??hole cantilever beam by special polymer. Bragg reflected wavelength is shifted and reflected bandwidth is broadened by pressure change, while temperature change just leads to the shift of reflected wavelength. In the temperature range 20～100 ℃ and pressure range 0～7.8 N, the precisions of temperature measure and pressure measure are ±1.1 ℃ and ±0.18 N respectively. The response curves of FBG have good linearity which are higher than 99.6%. Reflection spectrum has a steady figure through repeated measurement.

Based on the theoretical analysis and data simulation of the characteristics of the return signal, the factors influencing the capability of minimum depth of an airborne laser bathymetry and the improved technical methods are discussed. The use of narrow laser pulse, high-speed detector and small field-of-view can decrease the overlap of the surface and the bottom reflected signals. Based on the analysis of the characters of the surface and bottom reflected pulse, a method using double-Gaussian pulses fitting to separate the surface and the bottom reflected signals from the overlapped returns and to improve the capability of minimum depth using an airborne laser bathymetry is proposed to meet the applications of coast measurement. A simulated experiment was conducted and a minimum depth of 0.4 m has been achieved with the proposed method. The measurement results of the avalanche photodiode (APD) and the photomultiplier tube (PMT) are compared, the similar accuracy was obtained.

To calculate and to evaluate uncertainty of spot moment parameters measured with array detectors are the main goals. First, according to the integral expression of spot moment parameters, the corresponding discrete expressions of them are derived approximating zero order, and uncertainties of position and light power of every detector unit are analyzed preliminarily. General expressions of uncertainty of spot moment parameters are derived according to the transfer law of uncertainty. And then several simple forms of them are derived on corresponding conditions. So the methods of calculating spot moment parameters and evaluating the uncertainty of them are completely developed. Analysis on uncertainty of spot moment parameters measured with laser intensity distribution analyser (LIDA) and CCD are provided at last.

The dependence of radiation temperatures and coupling efficiencies of cavity targets on the target structures and laser irradiation conditions are investigated.Shenguang Ⅱ fundamertal-frequency laser with wavelength 1.053 μm, energy 3～5 kJ/8 beams, pulse width 0.6～0.9 ns is employed to irradiate gold cavity targets. The broadband soft X-ray spectrometer and flat response detector are used to measure the soft X-ray spectrum and its angular distribution from the diagnostic hole on cavity target. At the same time, technology of temporal and spatial resolution image with 5 pinholes is used to observe the X-rays emitted from the diagnostic hole on the cavity target, and then the correction factor of effective area of the diagnostic hole is obtained. Meanwhile, above-mentioned soft X-ray detection elements are calibrated by BSRF-3W1B beam in the region of 50～1500 eV to improve the irradiation power and diagnostic temperation.

Developments in double clad fiber lasers, coupled with engineered nonlinear optical materials such as periodically poled lithium niobate (PPLN), are opening a way for a whole new class of practical nonlinear optical devices. Temperature characteristic and spectra characteristic of second harmonic generaration (SHG) in PPLN using quasi-CW broad band fiber laser have been investigated. The central fundamental wavelength dependence of PPLN temperature and the temperature FWHM phase-matching bandwidth were theoretically studied. The fundamental wavelength FWHM phase-matching of PPLN was calculated too. The 20 mm long PPLN with 6.5 μm poling period and 0.5 mm thick was used for doubling frequency of the quasi-CW broad fiber laser. The spectra of second harmonic at different temperature are achieved and discussed in detail.

Locking laser source to a proper frequency standard can obviously improve the laser's frequency stability. Using two acousto-optic modulators (AOMs) to shift the saturation absorption spectra of cesium D2 line by tuning the DC voltage of the radio frequency voltage controlled oscillator's (RF VCO ) Vf inputing port the AOM shifted sub-Doppler spectra were gotten, and dispersion-like frequency discriminating signal was obtained by subtracting the two relatively shifted sub-Doppler spectra. Modulation-free absolute frequency stabilization of an 852 nm grating-external-cavity diode laser was demonstrated with a frequency shifting of 80 MHz. Thanks to this modulation-free locking scheme, the typical frequency jitter of less than ±270 kHz in 50 s, relative to the cesium hyperfine transition of 6S1/2 F=4??6P3/2 =5, was estimated in preliminary stabilization. The long-term frequency stability was greatly improved comparing with the frequency fluctuation of about 14 MHz under free-running condition in the same time scale. This scheme can avoid the extra frequency noise as well as intensity noise duo to the direct frequency dither on laser source in the conventional saturation absorption technique.

Beam-converting annular resonator (BCAR) possesses outstanding characteristics of high extraction efficiency and near-diffractive beam quality. It is applied specially to annular HF/DF gain medium. A finit difference method is used to calculate the modes of BCAR with various active medium. It showed that BCAR is insensitive to aberrations introduced by active medium, the optical quality is excellent, and extraction efficiency of BCAR is high under all the conditions. When a shock wave exists in the active medium, Strehl ratio of BCAR can still reach 0.899, the intensity distribution on cavity mirrors is reasonable, thus the damage possibility resulting from thermal load on the mirrors is lower than the usual unstable resonators. All above advantages make BCAR a very useful resonator applied not only to high energy chemical lasers but also to other high energy lasers with annular gain medium.

Quantum cascade laser (QCL) is a new-style laser whose wavelength remains in middle and far infrared. Hitherto its dynamic characters like pulse and modulation responses haven't been well acquainted. To ascertain this, an equivalent circuit model was derived on the base of rate equation of QCL that is invented by Bell Lab in 1994 by analyzing the unipolar transportation and transition behaviour of electrons in multiply quantum well, and the modulation response of QCL is gotten in the circuit simulation program PSPICE. Consequently some factors such as transition time between wells have been analyzed which could affect the modulation character of QCL.At last its dynamic character is found to be unexcellent compared with other lasers because of its peculiar energy band structure.

A novel cavity for improving the beam quality of diode direct side-pumped Nd∶YAG laser was proposed. The enfolded cavity consisted of three parts, a Porro prism, a high-reflectance mirror and a output coupler mirror. It made full use of the symmetry proportion of uneven gain profile to provide better matching between the gain volume and mode volume, so that the better quality beam and the higher optical-optical slope efficiency were obtained. The enfolded cavity was proved to be high effective by the results of experimentation and simulated calculation. For the quasi-CW laser diode side-pumped enfolded Nd∶YAG laser, a 27.3% optical-optical slope efficiency was obtained.

Rare-earth doped fluorophosphate glass is one of the laser materials that can meet the requirements of wavelength-division-multiplexing (WDM) system and ultra-short pulse system for bandwidth and flat gain. A wide-band, flat gain Yb3+∶Er3+-codoped fluorophosphate glass is investigated, and the calculated full width at half maximum (FWHM) is 51 nm. The study on effective gain cross section shows that there is a flat gain shape between 1530～1580 nm, which proves that the wide-band property of the glass is much better than that of phosphate glasses. The sensitization efficiency of Yb3+ on Er3+ shows that when Yb∶Er ratio is 10∶1, the absorption and emission cross sections of Er3+ reach the maximum of 0.6601 pm2 and 0.7325 pm2 respectively, indicating that in this ratio, energy transfer efficiency reaches the best. Results shows that Yb3+∶Er3+ codoped fluorophosphate glass can be a promising candidate as the media glasses for wide-band, flat gain, high output power lasers and laser amplifiers.

A wave coupling theory of linear electrooptic effect has been used to study the temperature dependence of electrooptic modulator. The numerical results of temperature dependence have been obtained from this method under different angels between incident light vector and crystal optical axis. The results show that temperature stability of electrooptic modulator can be obtained by angle modulation. An optimal design of electrooptic modulator has also been presented, which has the advantages of a very small zero-field leakage, a relatively small half-wave voltage, a large extinction ratio and good stability of output intensity versus temperature. And the design doesn't need transparent electrodes.

The critical behavior of nonlinear properties in the component composites is studied. The first component is assumed to be nonlinear and obeys the nonlinear current (Ⅰ)-voltage (Ⅴ) characteristic of form formula I=g1V+χ1Vβ, while the second component is linear with I=g2V, where g1 and g2 are linear conductance of constituents and χ1 is the nonlinear susceptibility and β is nonlinear exponent. The volume fractions of two components are p and 1-p respectively. The critical exponents of effective response is calculated by means of effective medium approximation and the relative resistance fluctuation method, respectively. The conclusions are the critical exponents of linear conductance M(β)=1 and nonlinear susceptibility N(β)=(β+1)/2 for all spatial dimensions d can be obtained within the effective medium approximation; while based on the scaling theory of the relative resistance fluctuation, the critical exponents depends on arbitrary nonlinear β and spatial dimensions d.

According to the development of the lightweight night vision device in the world and accelerating the research of the lightweight night vision technique, a hybrid optical system of head-mounted display used for lightweight night vision is designed. The parameters of objective are ±14° field-of-view and f=1.4. This objective with one diffractive surface can be compatible with second and third generation image intensifying tube with size of 18 mm and planar type of input surface. The maximal value of distortion could be ignored for it is less than 0.5% of objective and can be used to accurately measuring and aiming. Considering the safety problem, A see-through monocular display system is designed to deliver the information of the image and the real world to human eye with a holographic combiner. The features of display the system are 15 mm (H)×10 mm (V) exit pupil size, 25 mm exit pupil and [±14° (H)]×[±10° (V)] field-of-view. The resolution and distortion of display system are 0.6 mrad and 3%, respectively, and it can be matched with display size of 18 mm.

This paper presents the design and fabrication of a novel optically readable thermal imaging device based on Fabry-Perot micro-cavity array made on silicon substrate, which directly translates thermal imaging into visible imaging by using optically readable technology. The focal plane array(FPA) of this device is a Fabry-Perot micro-cavity array based on microelectromechanical system (MEMS) technology. The structure and thermo-mechanical designs of movable micromirror, and the design of the visible readable setup are completed. Theoretical analysis indicates

A novel kind of step-shaped nano-aperture with high resolution and high power throughput is proposed. The step-shaped nano-aperture's size is gradually reduced from the incident surface to the exit surface until a sub-wavelength aperture is formed on the exit surface. The step-shaped square aperture and the step-shaped triangle aperture have been numerically simulated by the method of 3-D finite-difference time-domain (FDTD). The calculation results reveal that the light intensity peak and the power throughput of the step-shaped aperture are increased by about 100 times or more in comparison with those of the ordinary non-step-shaped nano-aperture with a comparable light spot size due to the near-field optical local enhancement effect. For step-shaped triangle aperture with four steps, when the full-width at half-maximum (FWHM) of light spot is 97 nm×74 nm, the peak intensity reaches 1049.76 (1000 times of the incident light intensity) and the power throughput is 1.67. This kind of step-shaped nano-aperture can be directly used as an exit aperture of nano-aperture semiconductor lasers or as an unattached shield, to produce a sub-wavelength light source with high transmission. It is possible to be used in near-field optical applications such as near-field super-resolution imaging, high-density optical data storage, nano-photolithograhy, manipulation, and so on.

High-speed rotary Fourier transform spectrometer has nonlinearity of optical path differences (OPD) because of refractor's rotating. Nonlinearity is an important aspect to be considered when material of rotor and scan angle are chosen. It is studied to direct engineering and more studying here. Its effect on interferogram and reconstructed spectrogram are discussed. Nonlinearity of OPD can cause variance periodic of interferogram. And it introduces noise and wave number shift of reconstructed spectrogram. Since OPD can be calculated while refractor rotating, Nonlinear OPD can be replaced with corresponding linear OPD in Fourier Transform to compensate the nonlinearity of OPD. The computer simulation testifies this method being effective. Noise caused by nonlinearity in reconstructed spectrogram disappears after being compensated.

A possibility to measure glucose concentration using a Michelson partial coherent interferometer (LCI) is presented. For three different glucose concentrations, 0.18 mg/mL (hypoglycemia), 0.95mg/mL (normal level) and 3.36 mg/mL (hyperglycemia) the second-order dispersion is investigated over the wavelength range 0.5 μm to 0.85 μm, and the investigation shows that different concentrations are associated with different second-order dispersions. The second-order dispersions for wavelengths from 0.55 μm to 0.8 μm are determined by Fourier analysis of the interferogram. This approach can be applied to measure the second-order dispersion for distinguishing the different glucose concentrations. It can be expected as a potentially noninvasive method to measure glucose concentration in human body.

In the experiments of Rayleigh laser guide star (LGS) for adaptive optics on altazimuth Coudé telescope, the technology of LGS launched and received in the common aperture using polarizing beam splitting scheme is researched. Based on the Jones matrix method and the reflect characteristic of coating film on mirror, the physical model of polarizing beam splitting in altazimuth Coudé telescope is built. The efficiency of beam splitting for launching and receiving is simulated with numerical method in computer and compared with experimental result. The result shows that the efficiency of polarized beam splitting is periodically varying with the azimuth or elevation of the telescope because of the phase difference between the s and p polarizing vector reflected by film on the mirrors. The factors of degrading the polarizing beam splitting efficiency are analyzed. And a technical scheme for keeping the efficiency from degrading with the azimuth or elevation varying of the telescope is presented.

An adaptive-optics system usually contains wavefront sensing, wavefront conrection, wavefront reconstructing. So the system is complex and expensive. Deconvolution based on Hartmann-Shark wavefront sensing is a kind of “post-processing”, for it does not need wavefront correction and the system is less complex and less expensive. The principle is sensing wavefront in short exposal and recording blurred images at the same time, which are used in deconvolution. Incremental Wiener filter is first applied to image deconvolution from wavefront sensing. Images of point sources indoors with aberration are processed and restored by incremental Wiener filters. The results show that incremental Wiener filters can efficiently be used in image deconvolution from wavefront sensing. The resolution of restored images can reach a diffraction limit in terms of point sources indoors. Compared with Wiener filter, it extends the selection range of noise restrain coefficient. Even the noise restrain coefficient is not properly chosen, it still has better restored image quality than Wiener filters.

Inter-satellite communication needs near diffraction-limited laser. Wavefront testing of diffraction-limited laser is difficult through several techniques reported before. Double-shearing interferometer presented here including four wedges is designed on the basis of traditional Jamin lateral shearing interferometer. The wavefront aberration can be deduced from the different fringe spacing with half minimum wavefront height of single aperture. The apparatus and principle of the interferometer are explained. Some simulations and the experiment of 0.3 wavelength wavefront height are given also. Then it is clear that with this design it is easy to know the sign of the wavefront aberration and to evaluate the value by nakedeyes. The interferometer works in the equal optical path interference which is useful for laser diode etc. with shorter coherent length.

A rigorous coupled wave theory for the Bragg diffraction of a Gaussian beam in the uniaxial crystal is derived and a group of rigorous coupled wave equations and diffraction efficiency formula are obtained in terms of the proper coordinate transformation and Riemann method. The relations between the efficiency and the index modulation, the wavelength selectivity and the angular selectivity are discussed. At the same time, the requirement of the efficiency on width of the reconstruction beams is also analyzed. Simulation calculations show that, for the extraordinary to extraordinary (ee) Bragg diffraction, the possible maximum efficiency is determined by the incident angle of the recording beams. Moreover, by choosing every parameter properly, the theoretical efficiency can reach approximately 90% in the very low index modulation such as 8.2×10-5 for ee type Bragg diffraction. This model may give a theoretic guidance for how to obtain high efficiency in the low index modulation condition.

A method for measuring the Brillouin shift in water is investigated. It is based on the technique of the filters with resonant absorption of molecules. By using the two symmetric absorption peaks of iodine molecules within the frequency range of Brillouin scattering in water, accurate real-time measurement of Brillouin shift in water could be achieved. The principle of the technique is analyzed and a real system which can be used in practical applications is given. Also, the inherent errors and the sensitivity for measuring of the system are discussed. The experimental results using this method are given. It shows that this method has several advantages such as good real-time measurement, high sensitivity, high precision compared to the classical technique such as using Fabry-Perot.

Carbon nanotubes (CNTs) is a kind of prosperous field-emission material. It can be made as field emission cathode of X-ray source. In experiments, CNTs using as cathode is printed on glass base, the anode was made of Cu and processed to a cylinder with one end made to a hemisphere whose radius is 2 mm. High voltage supply are tunable in the range of 0～19 kV. X-ray source is stably runing for four hours at work vacuum of 1×10-4 Pa. At last, kα line spectrum is detected by the flow-gas proportional counter. The experimental results reveal that the emission of X-ray source are stable and CNTs is well fitted to X-ray source cathode. The fitful structure of field emission X-ray source was given out in the end.

Some experimental results of in vivo observing X-ray attenuation of intra-tumor injection of indocyanine green (ICG) are reported. An eight-to nine-week-old male BALB/c mouse with mass between 15 g and 20 g is used in the experiments. The mouse is implanted with myeloma cell line (SP2/0) two week before. A system used to monitor the intratumor diffusion of ICG is a digital X-ray imaging system. It works at 33 kVp, 0.3 mA with exposures duration of 4 seconds and magnification of 1.5. The objective of this research is to study the X-ray attenuation at different area, which represented by gray-scale value. Compare to the ROI in the tissue without ICG and ROI of black background in the image, there is an obvious change in the tumor, which is the area ICG can diffuse to. It shows the feasibility of using digital X-ray imaging system dynamically, effectively and noninterventionly to monitor the diffusion of the ICG.