Aerosol measurements in slant range in atmospheric boundary layer are performed by using a mobile pollution detecting lidar system (AML-1). The corresponding data processing method is introduced. By comparing the adjacent measurements performed by this mobile lidar in slant range and vertical range, the results show great feasibility of the slant-range measurement and data processing method. Two typical examples, aerosol extinction coefficients changing with height and time in 20° zenith angle and one two-dimensional scanning, are presented. These graphs show apparent space-time distribution of aerosol extinction coefficients, which is important to realize continual, simultaneous, large-ranged atmospheric pollution detection.

The multiple-beam propagating technique is one of the effective ways to mitigate the effect of atmospheric turbulence. The influence of atmospheric turbulence on multiple-beam atmospheric laser communication and the characteristics of optical intensity fluctuation after the multiple beams passing through atmospheric turbulence are analyzed theoretically. Then a new channel model of multiple-beam laser propagation through atmospheric turbulence is put forward applying the method of statistical analysis. The model is developed with 1) range z, 2) number of laser beams n, 3) laser transmitter spacing St, 4) receiver aperture Dr as variables. The model is validated by the experimental results in related reference. The results show that the multiple-beam approach with a proper aperture (Dr?恙?0) receiver and transmitter spacing (st≥λz) is a very effective way for intensity fluctuation reduction induced by turbulence, thus reduces the bit-error-rate of the atmospheric laser communication system. And the intensity fluctuation will provide a good match to log normal distribution with multiple beams.

A mobile differential absorption lidar (DIAL) system for atmospheric pollution measurements has been developed. It is the first mobile system for air pollution monitoring in China. This lidar system allows three-dimensional measurements by using a steering unit, and can measure four kinds of pollutants in atmosphereaerosol, SO2, NO2, and O3. The lower detection limit of the SO2, NO2, O3, and aerosol's extinction coefficient is 0.01 mg/m3,0.04 mg/m3, 0.01 mg/m3, and 10-4 km-1 respectively. The best spatial resolution and maximum measurement range are 7.5 m and about 3～10 km respectively. Using this system, range-resolved measurements with high sensitivity over large areas can be made. The lidar system in some detail and its performance are described.

A novel heterodyne reception of optical wireless communication adopting photorefractive multiple quantum well device is discussed. Compared with the conventional heterodyne scheme, it avoids the complicated intermediate-frequency tracking system. Compared with homodyne reception using multiple quantum well device, the noise is suppressed dramatically with the help of electronic intermediate-frequency filter. Consequently, the signal-to-noise ratio is improved. The theoretical expression of self-coherence signal is deduced. And the expression of signal-to-noise ratio is given. The impact on the novel heterodyne reception scheme is also analyzed in detail. An experiment of the scheme is conducted. The result of theoretical calculations and experiment show that the scheme can repress to a certain extent many problems due to laser transmission in the atmosphere. This new scheme can be applied to satellite-ground laser communication and terrestrial optical wireless communication.

With the increasing availability of high output power erbium-doped fiber amplifier and the development of highly nonlinear fibers, more gain saturation phenomena are observed in fiber optical parametric amplifiers (OPAs), which are expected to be avoided. A practicable method is proposed to avoid the gain saturation phenomenon, that is optimizing fiber length according to other parameters of fiber OPA, such as nonlinear coefficient, input pump power and input signal power. The concept of optimum fiber length is introduced, namely the minimum fiber length needed for the maximum signal gain or signal output power with other parameters fixed. The optimum fiber length is of great benefit to boost the gain bandwidth and the conversion bandwidth. By solving the nonlinear coupled equations that govern the fiber parametric amplifying process with numerical integration as well as adopting controlled variable method, the optimum fiber length as a function of nonlinear coefficient, input pump power and input signal power is profoundly studied. Finally, coefficients are figured out with least square method, and a pithy and useful analytical expression for the optimum fiber length is presented. Compared with existing experimental result, this analytical expression could be soundly used to optimize fiber length for fiber OPAs.

Wide-bandwidth chirped fiber Bragg grating (FBG) has been fabricated using precisely scanning phase-mask technique. Two ends of the mask by ten percent length are coated, whose transmissive characteristics approximate fourth order Gaussian function. The maximum delay ripple of the chirped grating written by such a phase mask is about 20 ps.In order to decrease polarization mode dispersion (PMD) of chirped fiber Bragg grating, a novel method, which is called polarization mode dispersion-compensation written technique, has been developed. Differential group delay of chirped fiber Bragg grating by the former written technique is 9.1406 ps, but with the newly developed method it has been greatly reduced to 0.1521 ps. Such low polarization mode dispersion chirped fiber Bragg gratings were then used to compensate the dispersion of 40 Gb/s optical time division multiplexing transmission over 122 km of G.652 fiber

Based on the birefringent effect of liquid crystal, a liquid crystal Fabry-Perot filter in simple structure is designed and fabricated. This device can be used in wavelength division multiplexing. The tunable characteristic of this device was analyzed and simulated; the formula of the relation between the liquid crystal refractive index modulation and the rotary angle of the liquid crystal molecule arose from the modulated voltage is got. The test of the fabricated tunable filter shows that the performance of the device is mainly affected by the alignment of the liquid crystal molecule and the parameter of the reflectors of the Fabry-Perot cavity, and the tunable characteristic is good for this kind of device with the nematic liquid crystal as the media in the Fabry-Perot cavity. The tunable range of the tunable filter covers the C band and the full width at half maximum (FWHM) could reach 0.8 nm, the experimental result was coincident with the design well.

A new method of analysis of intensity modulation is proposed for phase unwrapping of equal-step phase-shifting interferometry. By analyzing the intensity modulation of interference speckle patterns, a variety of noise, inconsistence and invalid data area can be identified. A binary and decimal weight can be constructed by this method for weighted phase unwrapping that utilizes least-squares approach and enhances the immunity of phase unwrapping from kinds of disturbing factor. The application of this method to Carré algorithm and Stoilov algorithm is discussed. The experimental result shows the validity and praticality of this method. A comparison of the performance of binary and decimal weight in weighted least-squares phase unwrapping is provided.

A new method of cathode-ray tube (CRT) monitors characterization is proposed. The features of this method are, it adopted a vision matching method to map some color appearance factors between self-luminous body and reflector surface colors, but without the complexity of using any color appearance model. It is a method that it has considered some color appearance factors. The neural networks were utilized to realize nonlinear mapping in color space. The experiment indicated that the method may improve the reproduction colors in different CRT when an arbitrary assigned color is to be displayed on a CRT screen, in office environment. Some simple network structure and small samples training method were adopted. The average color difference of training samples is 3.07 L*u*v* unit and that of testing samples is 4.55 L*u*v*. These results are smaller than the biggest acceptable color difference 10 L*u*v* unit. The results are satisfying. The method can be widely used by electronic-commerce and automation in office

A modified Wiener filtering method for image restoration of the ring-coded aperture images in inertial confinement fusion (ICF) is presented. In traditional Wiener filtering method, the signal-to-noise ratio of spectral density has to be replaced with a constant parameter, which overlooks the spectral information of the underlying image and noise because the spectra are a priori unknown, and consequently the filtered result may lose some important details with inadequate resolution. In order to overcome this drawback, the authors propose an approach to exploit the spectral information. In the new method, the traditional Wiener filter is used at first to obtain the initial estimate of the target image, based on which the spectral densities of the target image and noise image are estimated. Then by using this information a new Wiener filter is reconstructed that is used to filter the coded image again to obtain an improved result. The validity of the new method is confirmed by the experimental results

During injecting high temperature and pressure steam into an oil well, it is important to economize energy and raise yield if the vapor-to-water ratio continuously from the mouth to the bottom of the oil well is known. Because the vapor and water have different refractive indexes, the vapor-to-water ratio can be deduced from the response characteristic of refractive index of two-phase flow. The developed device, which adopts sapphire as the probe, can respond to the change of vapor-to-water ratio directly, and can be used in small working space in the steam with high temperature and pressure. The response curve gained by the test in a boiler pipe is accordant with the real situation of vapor-water ratio of the steam transportation. The device also works in a steam injection oil well with depth of 800 m, temperature of 270 ℃ and pressure of 10 MPa at well mouth. The experimental result is helpful to analyze the information of steam injection well of oilfield.

The technique of Brillouin scattering-distributed optical fiber sensing has been presented and demonstrated experimentally. Brillouin scattering light is very weak, has frequency shift with the Rayleigh scattering light. So microwave electric optical modulation is adopted to produce frequency-adjustable reference light, which is heterodyne detected with Briilouin back-scattering light. The detecting photoelectric signal is first converted into digital signal by hi-speed analog-digital converter, then the digital signal is stored and added, at last the distributed sensing signal with better signal-to-noise ratio is gained. The experimental procedures and results are presented. The results show that the frequency and light intensity of Brillouin scattering light vary with the change of temperature. The 25 km distributed sensing of temperature is achieved, and the primary results confirm that the configuration is feasible.

A new method for detecting circle with defects and noise using parametric deformable template is proposed. An energy function of the deformable template is defined according to geometric characteristics of the circle and gradient information of the image. The template then interacts dynamically with the image and energy function by altering its parameter values to maximize the energy function. The final parameter values (maximum) can give the location of the circle according to definition of the energy function. In order to raise the matching speed, a decreased search region is given by estimating values of the radius and the center of the circle. Then the energy function is optimized using greedy method in the search region. Experimental results show that the algorithm can localize the circle within a pixel and about 0.5 s; even the circle has defects and noise. This method has good resistence to interference and noise, and fast operation.

The results of spectroscopic study on the gas plasma induced by a pulsed laser with wavelength of 1.06 μm are reported. The gas samples are pure nitrogen, pure oxygen and air, all at the atmospheric pressure, and the spectral range studied is from 300 nm to 900 nm. The results show that the spectra of laser-induced plasmas for the three kinds of gas samples are composed of continuous spectra and line spectra, the basic features of the continuous spectra and line spectra were given, the possible connections of these spectra features to the characteristics of the laser-induced gas plasma were discussed, and the differences of the laser-induced plasmas between pure nitrogen, pure oxygen and air samples were analyzed. The basic features of time evolution and space distribution for laser-induced plasma spectra were also given and the relations between these features and the laser-induced plasma characteristics were briefly discussed. These results are helpful for the better understanding of the laser-induced plasma characteristics, especially those related to the relaxation process and the recombination mechanism of the plasma after its production.

Detectors are easy to be damaged by laser irradiation during optoelectronic countermeasures. Damage mechanism of semiconductor induced by high-power continuous-wave laser is investigated. The two-dimensional physical model that chemical oxygen-iodine laser (COIL) irradiates a disk target of InSb is established. The equations of heat conduction and thermoelastic dynamics are solved through integral-transform method in circular cylindrical coordinates. Transient distribution of temperature field and thermal stress field is described. The damage threshold of InSb is calculated, which is related to irradiation time and beam radius. The damage morphology of InSb is proved to be ablation, but no cleavage burst appears. It is in accordance with practice. The influence of temperature-related nonlinear parameter on damage threshold is analyzed.

A novel type of photopolymer holographic recording materials sensitive to red light and green light is presented. The photopolymerizable system comprises two monomers, a photoinitiation system, and an inactive component referred to as a binder. Diffraction efficiencies are no less 30%, and sensitivities are no less 25 cm2/J when exposed to red light and green light respectively. Spatial frequencies of red light ranged from 1600～2800 lp/mm, and the best response spatial frequency is 2274 lp/mm and the corresponding diffraction efficiency is 27.72%. Spatial frequencies of green light ranged from 1700～3000 lp/mm, and the best response spatial frequency is 2335 lp/mm and the corresponding diffraction efficiency is 25.72%. There is no crosstalk among reconstruction images when recording in the same point by red and green light, so the photopolymer is promising to two-wavelength multiplexing holographic storage.

The absorption spectrum, upconversion spectra and Raman spectrum of Er3+/Yb3+-codoped oxyfluorosilicate glasses have been investigated, and upconversion luminescence mechanisms of Yb3+ sensitize Er3+ in oxyfluorosilicate glasses were analyzed. The results showed that blue, green and red emission centered around 408 nm, 529 nm, 545 nm, and 667 nm, corresponding to the 2H9/2→4I15/2,2H11/2→4I15/2,4S3/2→4I15/2, and 4F9/2→4I15/2 transitions of Er3+, respectively, were simultaneously observed at room temperature under 975 nm diode laser excitation, and the intensity for blue, green and red emissions increases with the increasing Yb2O3 concentrations because energy transfer from Yb3+ to Er3+ was reinforced. A two-photon upconversion process is assigned to the intense green and red emission, respectively, while a three-photon process is responsible for weak blue upconversion. Raman spectrum indicates that the lead fluoride in the glass network play an important part in upconversion fluorescence of Er3+.

A novel and general model for light propagation in photonic crystal fibers (PCF) is proposed. A new method for constructing supercell lattice is proposed, the transverse index profile of PCF is represented with overlapping of two periodic structures and the modal field is decomposed by using Hermite-Gaussian functions. The propagation constant and the mode field distribution of the PCF can be calculated by recasting the Maxwell equations into matrix eigenvalue system. The transmission properties of PCF including modal field distributions, dispersion properties, polarization properties and effective area are analyzed. As a general method, it is an accurate and efficient model for square, honeycomb lattice and elliptical-hole PCF.

The signal intensity of phase-conjugation-type delayed-time four-wave mixing (TDFWM) with incoherent light is studied based on the two-level broad band model of semiconductor optical amplifier (SOA). The theoretical results show that the signal intensity not only decays with the dephasing rate of SOA but also pulsates with the delay time. Since the experimental investigation of both the carrier pulsation and the dephasing time using degenerate four wave mixing are limited only in the application cases of high-power laser, large optical experimental platform and sophisticated detection devices at present, a novel scheme composed of all-optical communication devices is proposed based on non-degenerate four-wave mixing. This means that both pump wavelength and probe wavelength not only are easily selected but also an experimental setup can be minimized.

A technique for simultaneous amplification and compression of ultrashort fundamental solitons is proposed. It is based on an erbium-doped nonlinear amplifying fiber loop mirror. Numerical simulations show that, unlike conventional erbium-doped fiber amplifiers in which nonlinear effects lead to serious distortion of amplified pulses, the proposed device performs not only distortion-free amplification but also efficient compression of ultrashort solitons. Using a 92.6 m erbium-doped fiber loop with a gain of 14.4 dB, the peak intensity of a 2 ps fundamental soliton is amplified by a factor of 165 with a compression factor of 10.48 and a time-bandwidth product of 0.303. The pedestal energy accounts for only 3.8% of the total energy of the amplified pulse which means that the pulse is very close to a fundamental soliton.

Different samples were prepared by doping azo dye 4'-[[2-(acryloyloxy) ethyl]-ethylamino]-4-nitroazobenzene (DR1), 4'-[[2-(acryloyloxy) ethyl]-ethylamino]-2-chloro-4-nitroazobenzene (DR13) and 4'-[2-2-(acryloyloxy) ethyl]-4-nitroazobenzene (DR19) in poly (methyl methacrylate) (PMMA) polymer films. The optical switching effects of the composites were measured by using linearly polarized 514 nm pump beam from an Ar+ laser (514 nm,CW) and a linearly polarized probe beam from a He-Ne laser (632.8 nm, CW). It was found that the sample containing the chromophores with strong pull/push electronic potential showed larger birefringence but slow response, which mainly came from the photoinduced reorientation process of the chromophores. The sample containing the chromophores with weak pull/push electronic potential showed small birefringence but fast response, which was attributed to the faster angular hole burning process of the chromophores.

An efficient pure blue multilayer organic light-emitting-diode employing amino-substituted distyryl arylene derivative (DSA amine, BCzVB) doped into 4,4′-N,N′-dicarbazole-biphyenyl (CBP) is reported. The device structure is ITO (indium tin oxide)/TPD (N,N′-diphenyl-N,N′-bis (3-methyl-phenyl)-1,1′biphenyl-4,4′diamine)/CBP

The relation between the air gap thickness and the peak wavelength in micro-optical electromechanical system (MOEMS) optical tunable filter based on Fabry-Perot etalon is discussed. In the devices based on MOEMS, length of the air cavity is about one wavelength, so the phase shift on reflection of the dielectric reflector plays a crucial role in the low interference order. From the phase shift, the linear relation between the air gap thickness and the peak wavelength is presented and then proved by numerical computation. The refractive index of thin films and the number of stacks constructing the reflector that influence the tunable sensitivity are analyzed. At the end, error in a specified wavelength range is estimated.

The imaging theory and several realization ways of optical synthetic aperture telescope are presented. Based on fast Fourier transform (FFT) algorithm the point spread function and optical transfer function of a random optical synthetic aperture system are obtained, then the imaging characteristics of optical synthetic aperture telescope are analyzed from such aspects as sub-aperture configuration and arrangement, cophasing and image restoration. The influence of sparse ratio, fill factor, “practical cut-off frequency” on optical synthetic aperture telescope imaging is investigated. The analysis and simulation indicate the optical synthetic aperture technology by coherent imaging can improve the resolution dramatically compared with traditional single-aperture telescope. It is valuable for realization of lightweight and modularity of space-based optical remote sensing system.

A high-accuracy optimization method for beam shaping, the marginal phase correction, is presented for correcting the phase of the diffractive optical element (DOE) designed by ray tracing to generate a ring-shaped beam. Using an instance of converting a Gaussian beam into a ring-shaped profile, the shaped results of DOEs designed by this new approach, Gerchberg-Saxton (G-S) algorithm and improved Gerchberg-Saxton algorithm are compared. The compared results show that the Gerchberg-Saxton algorithm simultaneously brings about high diffraction efficiency and large root-mean square value and maximum error; the improved Gerchberg-Saxton algorithm can effectively decrease the root-mean-square value and maximum error but also drop down the diffraction efficiency too much; this new approach can balance the diffraction efficiency, root-mean-square value and maximum error to obtain the least root-mean-square value and maximum error upon the slight decrease of diffraction efficiency. The shaped ring of the beam by this new method approaches a perfect ring.

A sinusoidal phase-modulating Fabry-Perot interferometer is proposed. A CCD image sensor is used for measuring the distance between the transmitted beams from the two faces of the Fabry-Perot plate. From the distance, the initial angle of incidence is calculated. The sinusoidal phase-modulating interferometry is used for improving the measurement accuracy. It is insensitive to the external disturbance. Numerical calculation and experimental results make it clear that the interferometer allows high-accuracy measurements of angular displacements. The sensitivity is of the order of 10-8 rad.

Under specific processing conditions, the nonlinearity of photoresist is strong, which can be advantageously used to make rectangular holographic grating masks. In order to clarify the relationship between the fabrication conditions and the groove profile formation, a model for simulating the development of photoresist grating is presented. The theoretically simulated groove profiles are in good agreement with profiles obtained from SEM photographs of fabricated gratings. Based on this model, combined with using a rigorous code for modeling grating diffraction, the efficiency of the reflected -1st order of diffraction is simulated as a function of development time. The main features of the simulated curve are found to coincide with those of the experimental in-situ monitoring curve. It is verified that the remarkable nonlinear effect of photoresist must be accompanied with a vast difference of etch rate between the center of a bright fringe and the center of its neighboring dark fringe. The model has been demonstrated capable of characterizing the influence of fabrication conditions on holographic grating groove formation.

Some experimental results and the principle of X-ray diffraction enhanced phase contrast imaging are presented. It demonstrates that X-ray diffraction enhanced phase contrast imaging is an approach with higher ratio of signal-to-noise than that of traditional X-ray radiography, the resolution can be up to 10 μm. It's a promising tool for the applications in researches on clinical, medicine and material sciences.