The GaN∶Si films were grown by MOCVD methods on (0001) sapphire substrates by using three different reactors. The opto-electrical and crystalline characterization of GaN∶Si films were measured by photoluminescene (PL), Van der Pauw Hall method and X-ray double crystal diffraction technique at room temperature, respectively. The results indicate that reasonable mixture time of group Ⅲ and groupⅤgas flows is important to improve the quality of GaN∶Si films. When group Ⅲ precursor mixes too early with groupⅤammonia, in other word, the time of the mixture is too long, the ratio of yellow luminescence intensity to band emission intensity is large, and the FWHM of X-ray double crystal diffraction is broad. When group Ⅲ precursor mixes too late with group Ⅴ ammonia, it will cause the opto-electrical and crystalline properties of GaN∶Si films poor due to inhomogeneous mixture even though the parasitic reaction became weak. GaN∶Si films with good opto-electrical and crystalline properties are obtained in B-type reactor.

Reducing the soliton interaction by the sin-sliding-frequency guiding filters is suggested. The effects of the up-sliding-frequency guiding filters, down-sliding-frequency guiding filters, zigzag-sliding-frequency guiding filters and sin-sliding-frequency guiding filters on reducing soliton interaction are numerically studied. The results show that the sin-sliding-frequency guiding filters is most effective in reducing soliton interactions.

Dispersion-flatten fibers are used to suppress the third-order dispersion to some extent based on the effect of third-order dispersion on pulse transmission by polarization multiplexing technique with zero dispersion wavelength. However dispersion-flatten fibers are only useful in short distance transmission. A new method is proposed to compensate the effects of the third-order dispersion by means of the cascade of many short fibers with alternate positive and negative values of the third-order dispersion. The method is proved practicable in long distance transmission by numerical simulation.

The influence of photo-detector array on the resolution and wavelength accuracy of the spectrometer is studied in both spatial-domain and frequency-domain. Main parameters of spectrometer, such as the center-distance of the photosensitive elements and width of spectral line etc., have been investigated deeply, and computational simulation is presented. A contradiction between resolution and wavelength accuracy is revealed when the width of one Gauss spectral line is less than five times of the center-distance of the photosensitive elements. The conclusion of one spectral line covering 5 sensing element is predicted.

The classical digital speckle correlation method of deformation measurement is based on gray correlation between the images before and after deformation. In fact, this kind of images are fractal and its fractal dimension represents both gray and morph information. A fractal dimension correlation method of displacement measurement is developed. This new method fully takes the advantage of the correlation behavior of digital images, so, it could be more precise than the classical one. In order to verify validity of it, an experiment is designed. The result shows that its precision is better than 0.06 pixels.

A tracking compensation technique for intensity modulation laser optic fiber sensor system based on radial basis function neural network is presented. The less influence of laser output power fluctuation and nonlinear calibration of sensor are realized simultaneously with this method. Long-term stability of sensor is improved. A broad measuring range and an enhance measuring accuracy of the sensor can be obtained. An example of optic fiber displacement sensor is illustrated. The result indicates that the method is effective.

The wake-field excitation by intense laser pulse in rare plasma is investigated. The wake-field excitation depends on laser pulse width. The resonant condition is given, as the laser intensity increases, the optimum laser pulse width decreases from the half of the plasma wavelength in a very low laser intensity. In rare plasma, the strength of the wake-field depends on the background plasma density, while the maximum wake potential of wake-field is dependent on it.

The propagation characteristics of ultrashort high-power laser pulses through low density plasmas is analyzed by considering relativistic effects. The expresssions of refractive index, electron density, electrostatic field and the dimension of electron cavity are derived. For laser power exceeding the dritical power of self-guiding, self-guiding occurs and laser beam oscillates along the propagation direction. For the laser power exceeding the critical power (P c≈2.5 TW) of the electron cavitation, electron cavity occurs. The expression of the electron cavity dimension is presented. With the laser power increasing, cavity dimensions are almost independent to the laser power, which implies that the electron cavity prevents the further focusing of the laser pulses.

Two methods were used to shape the spectrum of laser pulse. The birefringent filter of quartz crystal with the certain thickness was inserted into the Ti∶sapphire regenerative amplifier cavity for the regenerative amplifier intre-cavity spectrum shoping by adjusting the optic axis orientation of the crystal. Through the spectrum shaping, the bandwidth of the regeneratively amplified pulse was increased from approximately 20 nm to approximately 35 nm, which is near the bandwidth of the seed pulse. As a comparison, by using a coated filter outside the regenerative amplifier cavity, the bandwidth of the regeneratively amplified pulse was stretched to approximately 28 nm.

The rate equations for integrated erbium-doped waveguide amplifiers (EDWA′s) pumped at 980 nm wavelength are analyzed using overlapping factors methods. An analytical implicit gain solution of EDWA′s is derived. Based on which an analytical threshold expression of pumping power is obtained, and overlapping factors between the erbium concentration and the pumping and signal light field intensity distribution inside the erbium-doped planar optical waveguide amplifiers are calculated. The effect of erbium-doped concentration on pump threshold power and the effect of pump power on gain are discussed.

The colloidal crystals of SiO 2 spheres were grown in cells of different thickness. The results show that the colloidal crystal grows much quickly in 0.07 mm cell than that in 1 mm cell, and the crystal quality in 0.07 mm cell is much better than that in 1 mm cell. In ultra-thin cell, the high quality colloidal crystal can be grown with large diametrical error of the silica spheres. The band gap of the colloidal crystal in 0.07 mm cell has a red shift of 24 nm over that in 1 mm cell.

Physical jet deposition (PJD) method was used to form the C 60Ni films, one of the transition metal fullerides films, which were made into the Al/C 60Ni/ITO(indium tin oxide) layered structure photovoltaic cells. The photovoltaic effect and the forward and backward current-voltage characteristic of the cells were investigated and compared with the Al/C 60/ITO films. The enhancement of photovoltaic effect and rectification of Al/C 60Ni interface was observed. It indicates the buildup of interface electrical dipolar field on the Al/C 60Ni interface, which was caused by the charge transfer from Ni atoms to C 60 molecules in the samples.

By selecting some glass compositions the transparent glass-ceramics containing mullite crystal phase are obtained. The luminescent behaviors of these glasses and glass-ceramics were investigated according to the absorption spectrum and fluorescence spectrum. The results indicate that the emission intensity of glass-ceramic will enhance when the crystallization temperature was increased in a limited range, as a result the effective luminescent efficiency of Cr 3+ ion will increase. The increase of Cr 3+ ion concentration will cause the increase of emission intensity of glass-ceramics, but it will cause concentration quenching and decrease the effective luminescent efficiency of Cr 3+ ion. The origin of 688 nm emission shoulder in the glass-ceramic fluorescence spectrum is discussed, and it is suggested that the 700 nm and 688 nm emission should be attributed to the split of 2E energy level.

The fluoroaluminate glasses doped with Tm 3+ were prepared. The spectroscopic parameters have been calculated for Tm 3+ doped fluoroaluminate (AYF) glass based on the measured absorption spectra using Judd-Ofelt theory. IR emission and frequency upconversion of Tm 3+ doped fluoroaluminate glass were investigated. The results show that the concentration quenching is more significant for 1.45 μm-emission ( 3F 4→ 3H 4) than for 1.77 μm-emission ( 3H 4→ 3H 6) under the 800 nm excitation. The mechanism of upconversion, excited at 655 nm, was proved to be a simple excited state absorption (ESA) process.

The phase matching for noncollinear optical parametric process is investigated. All the possible phase matching configurations and existence conditions for general noncollinear three-wave mixing interactions are derived for propagation within the crystal principal planes. The calculation expressions for the critical phase matching angles are presented wherever possible.

A theory of screening-photovoltaic solitons is improved in biased photorefractive-photovoltaic crystals. The self-deflection of screening-photovoltaic solitons arising from diffusion effects is investigated using perturbation analysis. It is concluded that are the center of the optical beam moves on a parabolic trajectory and the central spatial frequency component shifts linearly with the propagation distance. The self-deflection of screening-photovoltaic solitons can be controlled by changing the external voltage or by rotating the polarization of the light. When photovoltaic effect is neglectable, the nonlinear wave equation of screening-photovoltaic solitons is the nonlinear wave equation of screening solitons, and their self-deflection is the self-deflection of screening solitons. When the external electric field is absent, the nonlinear wave equation of screening-photovoltaic solitons is the nonlinear wave equation of photovoltaic solitons in the closed and the open circuit, and their self-deflection predict that photovoltaic solitons is of the self-deflection.

The effect of loss in the photovoltaic-photorefractive crystal on the solitary evolution of a Gaussian beam is investigated. It indicates that, for a given photovoltaic-photorefractive crystal and a proper Gaussian beam, the loss will give rise to the continuous change in amplitude and cross-section during the transmission of the incident Gaussian beam, and for long-distance transmission it will eventually lead to the divergence of the incident waves. For the strong mismatch case, the cross-section of Gaussian beam first compresses and then expands, while the amplitude at the beam center first decreases, then increases and decreases again. In the case of weak mismatch, the intensity and the cross-section will monotonically decrease. It is found that the loss in the crystal can make a mismatched incident Gaussian beam evolve to a matched one, and then become to a steady-state bright soliton.

The optical nonlinear properties of BTN-SubPc spin-coating films were measured by means of Z-scan technique using a mode-locked Nd∶YAG laser with 38 ps pulse excitation at 1.064 μm and 532 nm. The reverse saturation absorption at 532 nm and the two-photon absorption at 1.064 μm were observed and the corresponding coefficients were determined. The resonant value of 6.7×10 -10 esu at 532 nm and the off-resonant value of 6.1×10 -12 esu at 1.064 μm of third-order optical nonlinear susceptibilities χ (3) were measured respectively, which were much bigger than those obtained for phthalocyanines. These results show that BTN-SubPc films are promising materials for nonlinear optical applications.

The guided-mode propagation analysis method is used to analyze self-imaging effect of multi-mode interference (MMI) devices with two-dimensional confinement. And the three-dimensional full vectorial beam propagation method (BPM) is used to confirm the analytical results. The analysis indicates that the self-imaging effect can be widened to the two-dimensional confinement on the basis of the one-dimensional confinement.

The coupled rib waveguieds are analyzed by using Galerkin method based on the plane mapped boundary conditions. The results indicate that the coupling ability decreases with increasing of the rib height and attenuates exponentially with increasing of the waveguides separation. The field intensity distributions of the even and odd modes supported by the coupled rib optical waveguides are obtained. Comparatively agreeing with those previously published, the results can be used to optimize the structural parameters for photonic devices. In addition, the plane mapped boundary conditions eliminate the non-physical reflection, and the small matrix derived from this method promotes the computational efficiency.

An optical fiber acousto-optic phase modulator coated with piezoelectric ZnO is discussed. The geometry of optical fiber using ZnO coating presented and the basic theory of piezoelectric resonator of this geometry is analyzed. The equivalent network model for the optical fiber acousto-optic phase modulator coated with piezoelectric ZnO is given. And then the reflection coefficient is obtained by this model. Computer simulation is made according to the practical parameters.

The high-resolution absorption spectra of real and simulated atmosphere were recorded by using an experimental system, which includes a tunable pulsed OPO, an 8 m base-length white cell with optical length of 1 km, and a time-division multiplexing detector system. The sensitivity is 0.5×10 -6 cm -1 and resolving power is 0.02 cm -1. The high-resolution absorption spectra of real atmosphere near 1.315 μm have been measured and compared with the simulated spectra according to HITRAN 96 database. The strong lines of water vapor molecule fit very well and the relative errors of molecular line intensity of the most strong lines are less than 10%.

The principle of localization of a small object in tissues using an amplitude cancellation phase modulation system (or phased-array system) is explained by an analytical model of the diffusion approximation. The effects of various factors on localization of the object using Phased-array system are discussed, which include the relative phase and the amplitude between two sources, the absorption coefficient and the size of absorbers. A localization method independent of the relative amplitudes and phase between two sources is presented. The principle of the method is explained and its feasibility is proved theoretically.

The method of measuring new first-grade gauge block by phase-shift interferometry has been studied. Firstly, multi-frame interference patterns are captured by CCD, then the shape of the measured surface of the gauge and the assistant reference flat to be wrung are obtained by phase-shift arithmetic. In particular, the unwrapping wavefront principle and technology are studied when there are step and discontinuity in the gauge interference patterns. The discrete wave error is calculated, which is fitted to be a continuous and smooth surface. The measurement results of guage block length and dynamic argument are given.

The optical source of stable and wavelength tunable ultrashor pulse is the key technique for the future OTDM/WDM systems. In this paper, an experiment with 20 GHz injecting mode-locked fiber laser is reported. With a source of 10 GHz semiconductor diode laser, a stable injecting mode-locked fiber laser producing 12.4 ps pulses at a rate of 20 GHz with the tunable range of 16 nm is got.

A nonlinear-fitting-deconvolution method is put forward for improving the measurement spectral resolution of gas absorption spectra when the instruments function and the absorption line-shape are previously known. The simulated results and experiments show that the method can obviously enhance the spectral resolution and decrease the experiment noise of absorption spectra by gases in the laboratory. The method was used to the measurement of high-resolution atmospheric absorption-spectra in the White cell and the results are satisfactory, the effect of laser line-width was decreased.

ZnO films have been grown on C-plane sapphire substrate with the plasma-assisted metal-organic chemical vapor deposition (MOCVD) method. By using the X-ray diffraction (XRD) and calculation, it is found that there is tensile strain in the sample annealed for many times during the growing process, and compressive strain in the sample which is annealed only one time after growth. The photoluminescence spectra show that there is only one emitting peak at around 380nm for the sample annealed for many times and two peaks for the sample annealed for one time after growing.

According to the changes of the fluorescence spectra in PVK thin films after doping, it is indicated that the energy transfer between PVK and perylene was occurred in electroluminescence of doped PVK thin films. A model Hamitonian was presented to describe the luminescence of PVK after doping. It was found that the effective energy transfer between PVK and perylene is derived from the charge transfer between them. The maximum amount of transferred charges occur at a certain dopant concentration for a given doping PVK, and the occurrence of plateau region is due to the saturation at dopant concentration. The results are in good agreement with experiments.