The theoretical and experimental study of fiber grating multi-point sensing made. By means of defining the signal resolution factor of multi-point sensing, the condition of signal resolution has been analyzed, the mathematical expression of the sensing principle of multi-point temperature and strain have been given and the system multiplexing capacity by dominated optical source bandwidth has been researched. The fiber grating multi-point sensing network system with some features has been designed and realized. By using this sensing network system, the multi-point sensing experimental analyses and theoretical verification of temperature and displacement sensing have been completed in the two channels of the sensing network system. The experimental results are in good agreement with the theoretical analyses of multi-point sensing.

As for an interference optic fiber sensor, the characteristics of its performance are directly influenced by the spectrum width of light source. Based on the research of Fabry-Perot interference optic fiber sensor, its sensitivity is theoretically formulated. Futhermore, with the application of the mathematical analysis of the result by software MathCAD, the problem of how sensor sensitivity being influenced by the spectrum width of light souce is discussed. An experimental system of optic fiber interference with feedback function is introduced and is applied to the display of a resonance curve. Two important experiments with the application of the above system (one is a comparison experiment on the sensitivity of interference cavities of different lengths; the other is a light source experiment on different interference lengths) present

The filtering characteristics of the fiber loop mirror filter, which is composed of multi-stage high birefringent fibers (HBF) is studied. The theoretic transfer function of the filter made of N-stage HBFs, and the expression are obtained when N is 1, 2 or 3; the polarization independence of the filter is analyzed, and the relation between the frequency response and the parameter of filter such as the length, beat length of HBFs and the angles between HBFs is studied; finally, some experiments are performed to check the theory, and the result shows to have good agreement with the theoretic result. The filter, which is based on N-stage HBFs loop mirror, has better stability than all-fiber Mach-Zehnder filter, is flexible in application, and has the advantages such as polarization independence, low insertion loss and low cost, so it has potential application in the fields of demodulation of fiber sensor, tunable filber laser and fiber filter of optic communcatiion.

A cascaded Mach-Zehnder interferometer filter is used to construct a flat-top filter, but couplers' coefficients of the cascaded interferometer-based filter cannot be determined directely by the traditional transfer matrix way. An analogy between the cascaded Mach-Zehnder interferometer-based filter and the finite impulse response filter used in the signal processing is given, the transfer function of the filter can be explicitly expressed by the couplers' coefficients. Thus, some methods commonly used in digital filter design can be used to design the cascaded Mach-Zehnder interferometer-based filter. For a specified frequency response, the couplers′ coefficients of the cascaded interferometer-based filter are determined by the genetic algorithm. An example is given to verify the availability and efficiency of this method.

Gain and quantum conversion efficiency(QCE) of Er3+-Yb3+ codoped phosphate glass waveguide amplifier at large signal operation are studied. From the definition of quantum conversion efficiency the analytical expression relating gain, pump power and quantum conversion efficiency is obtained. By solving the rate and optical power propagation equations describing the Er3+-Yb3+codoped system, the effects of Er3+-concentration, Yb3+-concentration, the ratio of Yb3+-to Er3+-concentration, pump power and amplifier length on quantum conversion efficiency are discussed. It is shown that increase of Er3+-concentration and of amplifier length can improve quantum conversion efficiency, in order to reduce up-conversion caused by high Er3+-concentration, high Er3+-concentration must match corresponding high Yb3+-concentration, improvement of Yb3+-concentration reduces quantum conversion efficiency, the rate of 1～2 of Er3+-Yb3+ codoped concentration is available.

To reduce the thermal effect to beam quality in solid-state laser with high repetition rate, multimode optical fiber as phase conjugator has been experimentally investigated in an laser diode-pumped, electrooptical Q-switched Nd∶YAG laser with double-pass amplifier. The laser was operated on 100 Hz repetition rate and 20 ns pulse width. Perfect correction of laser profile distortion in amplifier and beam quality close to diffraction limit has been achieved. Pulse width of phase-conjugated laser was compressed to 7 ns while compression ratio reached 3∶1. Beam glitter has also been observed in lower pumping energy close to stimulated Brillouin scattering (SBS) threshold. With increase of energy coupled into fiber, that phenomenon was weakened, and higher stability was achieved. In the case of 5.3 mJ input energy, instability less than 14% is obtained, while SBS reflectivity and depolarization ratio were 32.6% and 7% respectively.

he reverse saturable absorption and optical limiting properties in naphthalocyanine lead, dissolved in dimethyl sulphoxide are studied by using a Q-switched,double frequency ns/ps Nd∶YAG pulse laser system at 532 nm with pulse width of 8 ns,repetition rate of 1 Hz. The experimental results show that the naphthalocyanine lead owns good optical limiting performance, and the ratio of effective excited-state absorption cross section to ground-state absorption cross section of naphthalocyanine lead is approximately to 15.21, which is larger than that of naphthalocyanine copper. The experimental results show that the optical limiting behavior is better than C60, and the excited-state absorption is the main cause of optical limiting. The experimental results approve that the heavy-atom effect increases the reverse saturable absorption which improve the power of optical limiting because they enhance the intersystem crossing rates.

A novel variable optical attenuator based on micro-electromechanical system is reported. The variable optical attenuator employs a low-cost simple structure design, capable of fast dynamic response (<2 ms), wide dynamic range (0～35 dB), low return loss (<-50 dB) and wide bandwidth. By utilizing precise electrical-discharge machining as an enabling technology, the design incorporates an electro-magnetically actuated silicon mirror rotating around a 100 m shaft and a miniature driven coil. The attenuation response is compared with the calculated result from a numerical theoretical model by using ANSYS, a finite element analysis software package, and a reasonably good agreement was obtained. The variable optical attenuator is scalable to a discrete array to implement dense wavelength division multiplexing channel equalization in various networking devices.

A method is proposed for multi-spectral image compression based on rectangle region of interest (ROI) coding of EBCOT, which does not lift the coefficients of wavelet domain and is complemented by code stream organization. When the code stream is organized, the distortion of ROI can be calculated approximately, which is used to adjust the code stream organization to meet the need of the peak signal-to-noise ratio (PSNR) of ROI. This procedure is adaptive. The decoder needs not to lift reversely the coefficients and works normally. If the distortion requirement is changed, the organization can be done again, but the T1 coding of EBCOT needs not be done again, so the algorithm is more efficient and more flexible. A fast computation of the slopes is proposed, by which not only the precision of the slopes is enough but also the floating point division and floating point expression of the slopes are avoided, so the system complexity is decreased. This method is suitable for multi-spectral image compression.

Based on discrete diffraction light, an algorithm of holographic grating bandwidth compression is proposed. As is known to all, the visual resolution of human eyes is quite limited. That is, human eyes cannot perceive the jump of light beams within the 8 mm-1 variation of space frequency (angle between two light beams is less than 0.30°). At first the frequency spectrum of diffraction light is sampled so as to make holographic grating diffraction discrete in space frequency, namely, in the grating code is included discrete frequency spectrum, which satisfies requirements of human vision. In this case, the fringe function of the grating becomes a periodic one, and what is needed, therefore, is to record a periodic functional value (sampling value). As a result, the sampling value of such fringe function can be effectively compressed. Subsequently, all sampling values of the fringe function can be restored in decoding right by means of copying. This method that can not only compress data but also upgrade transmission rate achieves the desired dynamic display.

The Ar+ 514.5 nm laser beam is used at non-simultaneous writing-reading process. As the signal beam is with extraordinary polarization and the polarized direction of the pump beam has an angle Ψ with its extraordinarily polarized direction, the two-wave coupling property of a Ce∶KNSBN photorefractive crystal is experimentally studied. Because of the effect of the fanning, the polarization configuration that both the signal beam and pump beam are with extraordinary polarization is not as optimized as it is expected. As the angle between the signal beam and the normal of the crystal face takes 11the gain of the signal beam reaches its maximum and the fanning noise is depressed greatly. while Ψ=30°, those can be explained that the ordinary component of the pump beam as an incoherent beam erases the fanning and the gain of two-wave mixing is enhanced.

The high-precision radiometric calibration technology is one of the primary technologies of modern remote sensing. The trap-based filter radiometer is a key unit of new optical radiometric standard detectors, and has potential applications in radiometric calibration of field, air-borne and space-borne sensors. The temperature characteristics of trap-based filter radiometer are a primary factor of affecting its precision and stability. Temperature coefficients of standard detectors are systematically studied within large temperature range (20～60 ℃) and at different wavelengths. A temperature controlling device is designed and is used to stabilize the temperature of trap-based filter radiometer with high precision. The temperature controlling device effectively decreases the temperature coefficient of trap-based filter radiometer by nearly one order of magnitude. The results will provide a reliable reference for the future design of standard detectors on-board different platforms and under various temperature environments.

The band structure and the optical transmission properties of the two-dimensional photonic crystal with complex dielectric constant, especially discussing on the case of negative imaginary part, are analyzed numerically with the plane-wave expansion method. The results show that the spontaneous emission of special light frequency that is in the range of photonic band gap is effectively restrained. A large enhancement of stimulated emission appears at the photonic band edges where the group velocity is small if the photonic crystal is with a little impurity atoms that have population inversion. This phenomenon will happen even if the dielectric constant difference between two dielectrics is very small. Generally, there is a small group velocity near the photonic band gap. Because the threshold of emitting laser is proportional to the square of group velocity, the lasing threshold decreases with a decrease in the group velocity. This might be used either to realize lasing operation near zero thresholds, or to supply a beneficial reference for fabricating optical amplification device.

The group-velocity-dispersion properties of photonic crystal fiber (PCF) were investigated in detail by equivalent-index model. The PCF discussed here is made of single material (SiO2), the total dispersion is determined by waveguide dispersion, so the total dispersion has been divided into waveguide dispersion and material dispersion. The dependence of waveguide dispersion on structure parameters is investigated. It shows that when the relative hole size f is fixed, the relationship between waveguide dispersion and the pitch Λ accords with the scaling properties of Maxwell equations; when the pitch Λ is fixed, the zero and the extremum positions of the waveguide dispersion are linear with f in prefer wavelength range. As examples, how to design the structure parameters for engineering the chromatic dispersion of PCF is demonstrated.

The equivalent-refractive index model is implemented based on the fundamental space filling mode (FSM), the photonic crystal cladding is considered as a uniform medium, then the photonic crystal fiber is considered as a step-index fiber. The mode characteristics of the photonic crystal fibers (PCF) are investigated in detail using the equivalent-refractive index model, including the propagation constant, the mode-field distribution, the power confinement factor, power loss and dispersion. With the PCF and SMF compared, it is shown that the PCF is almost an endlessly single-mode fiber. The PCF can be used to improve the pump efficiency of EDFAs because its power confinement factor is higher than that of the conventional erbium-doped fibers.

The Er3+-doped Al2O3 optical films have been prepared on SiO2 substrate by the sol-gel method and the dip-coating process, using the aluminium isopropoxide [Al(OC3H7)3]-derived Al2O3 sols with the addition of erbium nitrate [Er(NO3)3?5H2O]. The surface morphology and structure of the 0.01 (mole ratio, ibid below) Er3+-doped Al2O3 film have been analysed by the scanning electron microscope (SEM), atomic force microscope (AFM), differential thermal analysis-thermogravimetric analysis (DTA-TG), and X-ray diffractometer (XRD). The 0.01 Er3+-doped γ-Al2O3 film with a thickness of 8 μm through 15 dipping coating cycles, which possesses a face-centered cubic lattice with a (110) preferred orientation, is obtained from 0.01 Er3+-doped γ-AlOOH gel sintered at 900 ℃. The addition of 0.01 Er3+ in the γ-Al2O3 has no evident influence on the phase structure and preferred orientation of the film. The homogenous and porous 0.01 Er3+-doped γ-Al2O3 film has a crystal size of 30～100 nm, a pore size of 50～100 nm, and a surface roughness of 10～20 nm. The photoluminescence (PL) spectrum centered at 1.533 μm with the full width at half maximum of 36 nm is observed for the 0.01 Er3+-doped γ-Al2O3 film, which is attributed to the intra-4f transition between the first excited (4I13/2) and the ground state (4I15/2) of Er3+.

Photosensitive pre-polymer monomers are mixed together with nematic liquid crystal in certain ratio. Then the mixture is injected into the cells for liquid crystal. The surfaces of the cells are coated with alignment films and rubbed for anti-paralleled alignment. Phase separation between liquid crystal and pre-polymer monomers takes place when ultraviolet light is applied with the shielding plate covering on the cells, which results in the formation of liquid crystal/polymer phase grating. Since the liquid crystal rotates 180° along the cell surfaces with the effect of alignment films, the disadvantage of traditional liquid crystal grating depending on the polarizing direction of incident light is overcome, and the utilization efficiency of light is improved. The samples are checked up by optical microscope and He-Ne laser. The results indicate that the samples have clear grating structure, their diffraction efficiencies do not change with the polarizing directions of the incident lights and can be modulated by electric field. The PDLC gratings with low driving voltage could be fabricated easily. They show numerous potential applications including optical communication devices, diffractive optical elements, projection displays and light valve.

A new laser beam collimation method that combines fiber collimation technique with laser beam drift feedback controll is investigated. In this method, the laser beam drift is initially collimated by passing though a single-mode fiber, then it is collimated further by a feedback control system for the purpose of improving the direction stabilization of the laser beam. In this feedback system, the displacement drift and angle drift are not only measured respectively using a drift separation optical system and a drift photoelectric measurement system, but also each of them has a corresponding independent feedback control system to restrain itself, at the same time the coupling between them is decreased. Due to the single-mode fiber is used, the laser system is far from the beam drift feedback control system. So the temperature effect from the laser source on the collimation system is decreased and the collimation system can be easily arranged. By applying these techniques, the collimation precision and efficiency are improved and experimental results show the collimation precision for the laser beam drift can reach 0.7×10-7 rad.

Pupil filter is an important optical superresolution element. In fabrication, phase-only pupil filter is more difficult than amplitude-only pupil filter. Diffraction optics can be used to fabricate the phase-only pupil filter, but this pupil filter cannot be tunable. The application of liquid crystal in phase-only pupil filter makes the fabrication easy. But the large decrease of intensity and the limited phase changed depth complicate its use in phase-only pupil filter. A new way to fabricate the phase-only pupil filter with uniaxial crystal is put forward. This phase-only pupil filter can be easily used in application. And there is no distinct decrease of light intensity. By numerical calculation, the feasibility of this design is demonstrated.

For experimental setup to calibrate spectral radiance by applying a diffuse plane, the measured spectral radiance can be obtained through integral of spectral radiation flux entering the spectrometer. Calculation shows that the measured spectral radiance by the spectrometer is not equal to the spectral radiance on diffuse plane surface, there is a deviation varying with actual calibration condition. The effect caused by variation of distance between spectrometer and diffuse plane, angle from the light axis of the spectrometer′s entrance slit to the diffuse plane′s normal, distance between standard lamp and diffuse plane are analysed, and optimized conditions for spectral radiance calibration are obtained. Finally, the idealized spectral radiance calibration, spectral radiance limit when the viewing area shrinks to a point, and actual spectral radiance calibration by applying a diffuse plane of known bidirectional reflectance distribution function at optimized conditions are discussed.

For understanding the phase and transfer properties of optical wave propagating through negative refractive index medium (NIM) layer, the relations between negative refractive index, the value and direction of wave vector k, the coordinates and the phase have been investigated intensively. The results prove the peculiar direction of the wave vector k in a NIM layer results from its negative scalar magnitude. In the identical right??hand coordinate system within NIM and PIM layers, only this negative scalar needs to substitute in the numerical simulation, while the vector k should be determined by both the negative scalar and the unit vector k0(k0>0). Based on this analysis, a transfer matrix of optical waves in NIM layer has been derived. The primary results show that the spectra characteristics of TE and TM modes from the films comprising NIM and PIM layers have changed prominently.

Fourier phase is important information for optical synthetic-aperture (OSA) imaging. The observed object′s phase is located in interferogram fringes. Factors affecting the OSA interferogram fringes′ initial phase were analyzed in detail from the mechanism of interferogram fringes in the image plane. With the original point value and the fringe peak displacement, the initial phase can be obtained from the fringes. With closure phase method, the error phase caused by atmosphere disturbance unnormal of star light direction to baseline direction, and telescope mechanic system, can be eliminated, and the real object Fourier phase can be obtained at last. With a threshold method in the frequency domain, noise affecting fringe peak′s location can be eliminated. The role of closure phase method is talked in the image reconstruction with hybrid iteration method.

Dynamic optics is a subject, which studies dynamic imaging characteristics of optical system and optical components in dynamic status. Image stabilizing system is an important part of dynamic optical system. The aim of movement between optical components of optical system is to reach some goal, for example, goal of circumrotation of scanners of the scanning and tracking system is to capture and track target. In an imaging stabilizing system, when the optical instrument installed on some carrier, the motion of carrier causes the image motion, so causes the image blur, in order to keep the stabilization and clarity of picture, the optical components must have some relative motion. To apply a spacial remote sensor, the remote imaging analysis is the key problem. Based on image stabilizing theorydynamic optical theory, the analysis of image motion of spacial remote sensor is given. The result shows the concise concept and simple expression of this method, which is consistent with uniform coordinate transform method. Similarly, for the similar moving optical systems, the theory of image-stabilization is also applicable.

The progress of laser self-mixing technology is reviewed. Theory and recent research in the microscopic technology based on laser self-mixing interference effect is introduced. The experimental system of the self-mixing interference with He-Ne laser is established and satisfying power stability of the system is obtained. The microscope based on the laser self-mixing technology is investigated. The design, structure, adjustment and experimental result of laser self-mixing microscopic system is given. Finally the profile of the micro-ball made of glass is three-dimensionally imaged. The lateral resolution is 1 μm and longitudiual resolution is 15 nm. It's proved that the microscope based on laser self-mixing interference effect has great potential in the field of high-resolution imaging on the micro-objects.

In the design of electron beam deflection system with a large scanning field, determination of aberration is a practical problem. The relationship between the principal trajectory of electron beam exposure and aberrations has been investigated in combined round magnetic lenses and deflection system of SDS-3 electron beam machine. The double passageway principle in scanning system is used. Conditions of moving objective lens (MOL) are given and used for improving the performance of electron beam scanning system. The construction and the way to obtain the best trajectory have been analyzed. The structure of the electron beam focusing and deflection system of electron beam exposure machine is analysed with computer-aided design (CAD). The result of scanning system of this electron beam exposure machine indicates that the aberration of superimposed focusing-deflection system is so small that the dynamic correction is unnecessary. The electron trajectories are parameter of electrostatic deflection described in the vector form, the aberrations and structure equation are described in the integral form. The arrangement with 50 mm working distance at the 10 mm×10 mm deflection field with 0.005 rad aperture and 5×10-5 beam voltage ripple produces a total aberration disk of 0.03 μm before dynamic correction.

Research is done on the single-photon interference with two different Mach-Zehnder (M-Z) interferometers-particle and fiber separately. Achieving the high contrast above 90%, the experiment approves the routing control of single photon with Mach-Zehnder interferometers of particle and fiber successfully. Pulse-modulating and attenuating techniques are implemented to get the single photon, and the subsingle-photon source is achieved with only 0.1 photon in one pulse. The routing control of the single photon is under the control of the changing of PZT power. Furthermore, the synchronous single-photon coincidence detection technique is used to detect the single-photon, modulation with repeating frequency of 10 kHz and pulse FWHM of 100 ns, the high sensitive detection is improved with high quantum efficiency over 70% and the dark count below 0.2 s-1, single-photon output through the chosen path with given chosen PZT power has been observed. The experiment verifies that single-photon routing control can be achieved in Mach-Zehnder interference.

A mathematical model, which describes stability of imaging system, is provided. While objects consist of two kinds of brightness and have periodic structure, it is proved, that intensity of pixel on image sensor of unstable image system accords binomial distribution. So image statistical parameter can be applied to describe system velocity and image instability. In order to research the rule of image stabilization at different times, the standard deviation, which indicates discrete degree of data in statistics, is introduced as descriptive factor. Finally, the curve, which described transformation process of Pechan prism system, is given. The fluctuation of the curve is in accordance with the stability change of observed image. This conclusion proves the provided method is reasonable and effective.

CW laser output is obtained using laser diode end-pumped polycrystalline transparent 10% Yb3+∶Y2O3 ceramic. The pump threshold is 5.6 W, the maximum output power of 5.48 W is obtained with the absorbed pump power 31.11 W, and the slope efficiency is as high as 25%. At the same time there is no saturation in laser experiment, so the higher power output of Yb3+∶Y2O3 ceramic can be obtained with laser diode of higher power. Therefore Yb3+∶Y2O3 ceramic is a potential laser material.

A flat-field spectrograph with self-scanning photodiode arrays detector is introduced. It is Czerny-Turner structure, spectral resolution is 0.5 nm per pixel. Wavelength calibration and radiance calibration method by using standard DC mercury lamp and tungsten lamp are described, with the spectrograph, 290～450 nm solar ultraviolet/atmosphere spectrum is measured and the measured results are given. Characteristics of detector is discussed. In order to restrain influence the temperature drifting on measuring result, some pixels at the two ends of CCD array are masked with mechanic structure, they are looked as background reference pixels, just as dumb elements. Real-time background subtracting restrains the impact of temperature drift and dark current and dark noise. According to the structure of instrument, the influence of the slit width on spectral line is discussed, the relative measurement error of instrument is also analyzed.

In order to obtain high gain X-ray laser based on the optical field ionization (OFI) induced plasmas, the electron temperature in OFI plasma must be controlled. The dependence of the electron residual energy on laser parameters such as polarization, wavelength (frequency), laser intensity and media ionization potential is calculated quantitatively using quasistatic tunneling ionization model. According to the calculated results it is noted that the electron residual energy is lower either the short-wavelength laser with linear polarization or the medium with high ionization potential is used, thus it is suitable for recombinational mechanism; the residual energy is highest when the polarization α is at some value of 0～1, thus the value of polarization α can be tuned and some elliptical polarized laser can be obtained, which may be in favor of the realization of electron-collisional X-ray laser. So higher gain values can be got.