The antireflection properties of triangular shaped gratings are studied by a combination of the effective medium theory and the anisotropic thin-film theory. The triangular shaped structures are analyzed as a function of grating period, filling factor, and groove depth, and the antireflective characteristics are also studied when visible-infrared light is incident upon them. Numerical examples are given for gratings on glass substrate with refractive index of 1.5. The results show that this kind of grating is capable of reducing reflections, and could achieve very low reflectivity over a wide field of view and a wide waveband by choosing appropriate parameters.

Polarization effect in parametric amplifiers is studied. Coupled equations are derived from the basic propagation equations and numerical solutions are given for both one-wavelength-pump and two-wavelength-pump systems. Several parametric amplifiers driven by pumps at one wavelength and two wavelengths are analyzed and the polarization independent parametric amplifier is proposed.

A kind of novel architecture of unslotted photonic packet switching wavelength division multiplexing (WDM) ring network with tunable transmitters and fixed receivers was proposed. In the network the wavelength was used as optical packet label and node media access controller (MAC) address. Optical packets transmitter was made up of tunable laser that was modulated at 10, 40 Gb/s or higher. Optical packet receiver was made up of Bragg grating, circulator, and fixed receiver. Used as metropolitan access network, it is shown through simulation how a multi-token MAC protocol can be implemented to avoid packet collision and achieve efficient bandwidth utilization. Packet delay, throughput, and packet dropping probability results are presented under uniform and none uniform Possion traffic.

Nonvolatile holographic recording is performed with green light in LiNbO3:Ce:Cu crystals. The refractive-index change and the recording sensitivity are times better than those obtained by recording with red light, and higher optical fixing efficiency is obtained. Correspondingly, theoretical investigations are given.

Mutual information (MI) based image registration has been found to be quite effective in many medical image applications. However, standard MI hampers the convergence of registration transformation parameters since it contains local maxima. In this paper, a novel registration method is proposed. At first, MI based on edge width matching is computed to avoid great change of joint probability distribution and get less local maxima. Particle swarm optimization (PSO), which combines local search methods with global ones balancing exploration and exploitation, is done to search the optimal registration parameter. PSO has less computational complexity as its complex behavior follows only a few simple rules. It could avoid local maxima and reach global optimal results. This method is applicable to a variety of multimodal images, and suitable to different interpolation methods. Theoretical analysis and experiments show that this method is effective and accurate to register multimodal medical images.

A new dual-frequency laser displacement measurement interferometer with nanometer precision has been developed. An eight-pass optical subdivision technology is proposed to improve resolution based on commercial interferometers. A static positioning error measuring method has been used to examine the precision and repeatability of the laser interferometer. An optical resolution of 1.24 nm and an accuracy of nanometer scale have been achieved.

In this paper, according to the features of easy distortion and scratch for aspheric plastic lens, a non-contact measuring method is raised to test error in shape of the lens. Namely, the distance between a template and its image reflected with tested lens can be measured in nearly the vertical direction of the lens axis when the two-dimensional (2D) template is put near the measured surface. Then, the outline of the central cross-section could be obtained by calculating and curve fitting. Furthermore, three-dimensional (3D) surface can be imitated through rotating the component. A new fitting method of drift measurement is presented to prevent reducing precision when the lens and the template are fixed. The template is adjusted according to the position of the lens. The measurement precision is in the order of magnitued of sub-microns. Rotationally symmetric convex aspheric surface with any angle can be measured by this method.

By modulating the pump current, we developed a passively Q-switched diode-pumped all-solid-state laser with a repetition rate stabilized up to 10^(-7). It was experimentally demonstrated that the stability could sustain for an arbitrarily long time. Moreover, the stabilized repetition rates which were synchronized with different modulating frequencies were tuneable in a wide range, by adjusting the period of the pumping cycle only. The output single-pulse energy was also stabilized, which was independent on the pump power after reaching a saturable value.

A new method of frequency-shifting for a diode laser is realized. Using a sample-and-hold circuit, the error signal can be held by the circuit during frequency shifting. It can avoid the restraint of locking or even lock-losing caused by the servo circuit when we input a step-up voltage into piezoelectric transition (PZT) to achieve laser frequency-shifting.

Nd-doped phosphate glass belt lasers pumped by laser diodes are demonstrated. The Nd-glass belt with a large cross-section and a small Fresnel number is air-cooled to provide around 18-W continuous wave (CW) output power with a beam quality factor of My2 * Mx2 = 16 * 3.2. With 6 pairs of V-grooves scribed on the edges of the glass belt, the beam quality is improved to My2 * Mx2 = 3.5 * 2.8 with output power of 13.5 W.

Roles of Y2O3 in mechanical properties of the bioceramic coating by the laser cladding were reported in this paper. The bonding strength of interface between the laser coatings with/without Y2O3 and substrate Ti-6Al-4V (TC4), bending strength, compressive strength, tensile strength, and hardness in these coatings were contrastively tested, and the ceramic-metal interface was observed by scanning electronic microscopy (SEM). These results indicated that the rare earth was the important factor which influenced the mechanical properties of the coating. Y2O3 was adequately dispersed in the melting pool of the laser coating, crystal grain got smaller after the melted coating was cooled, the impurity existing in crystal interface was reduced by chemical reactions, and so the strength was evidently improved. On the other hand, the rare earth could also obviously increase the hole numbers in the coating and decrease the compressive strength. So the effects of the rare earth on the laser coating were intricate and all-purpose.

A novel coupled quantum well structure --- quasi-symmetric coupled quantum well (QSCQW) is proposed. In the case of low applied electric field (F = 25 kV/cm) and low absorption loss (α ~ 100 cm^(-1)), a large field-induced refractive index change (for TE mode, Δn = 0.0106; for TM mode, Δn = 0.0115) is obtained in QSCQW structure at operating wavelength λ = 1550 nm. The value is larger by over one to two order of magnitude compared to that in a rectangular quantum well (RQW) and about 50% larger than that of five-step asymmetric coupled quantum well (FACQW) structure under the above work conditions.

The thermal stability, Raman spectrum and upconversion properties of Tm^(3+)/Yb^(3+) co-doped new oxyfluoride tellurite glass are investigated. The results show that Tm^(3+)/Yb^(3+) co-doped oxyfluoride tellurite glass possesses good thermal stability, lower phonon energy, and intense upconversion blue luminescence. Under 980-nm laser diode (LD) excitation, the intense blue (475 nm) emission and weak red (649 nm) emission corresponding to the 1G4 -> 3H6 and 1G4 -> 3F4 transitions of Tm^(3+) ions respectively, were simultaneously observed at room temperature. The possible upconversion mechanisms are evaluated. The intense blue upconversion luminescence of Tm^(3+)/Yb^(3+) co-doped oxyfluoride tellurite glass can be used as potential host material for the development of blue upconversion optical devices.

A soluble poly(2-methoxy-5-decoxy)-p-phenylene vinylene (PMODOPV) was synthesized via dehydrochlorination reaction and characterized by UV-visible absorption spectrum. The results showed that PMODOPV had a broad optical absorption band in the range of 450---550 nm and the optical band gap was calculated to be around 2.12 eV. The third-order nonlinear optical susceptibilities (χ(3)) of PMODOPV films implanted by 30-keV N+ ions in the dose range of 3.8 * 10^(15)---9.6 * 10^(16) ions/cm2 were measured by degenerate four-wave mixing (DFWM) technique. The results demonstrated that the resonant and off-resonant χ(3) values were all enhanced significantly by means of ion implantation. The maximum resonant χ(3) value of 9.67 * 10^(-9) esu at 532 nm and off-resonant χ(3) value of 2.49 * 10^(-10) esu at 1.064 μm were obtained when the ion dose was 3.8 * 10^(16) ions/cm2.

Amorphous bulk composites were prepared by doping azo-dye disperse red 1 (DR1) in poly(methyl methacrylate) (PMMA) matrices. Photoinduced anisotropy of such kind of bulk polymer material was investigated experimentally by measuring the dichroism when irradiating with linearly polarized green light with different polarization direction. With the interaction of bi-photonic beams at 514 and 632.8 nm, transient gratings in the bulk composites could be established, which was a kind of population gratings of trans and cis DR1 isomers and was attributed to the weak absorption of cis isomers at 632.8 nm and the positive dichroism of trans isomers at 514 nm. Furthermore, the all-optical switching behavior of the transient holographic gratings was observed repeatedly by turning on and off the writing beams and a response time of ten milliseconds order could be obtained.

A way resulting in lasing without inversion (LWI) in an open resonant Λ-type system from a nonlinear dynamics viewpoint is investigated. The destabilization of the non-lasing solution can occur not only through pitchfork bifurcation, giving rise to continuous wave LWI, but also through Hopf bifurcation, giving rise to self-pulsing LWI. This is much different from that of the corresponding closed resonant Λ-type system in which the destabilization of the non-lasing solution can occur only through pitchfork bifurcation. The effects of the unsaturated gain coefficient, cavity loss coefficient, atomic injection and exit rates on the two bifurcations are discussed.

The spectral radiation characteristic of a non-luminous flame is analyzed. The apparatus and the calibration procedure based on infrared emission spectrometry for measurements of the flame are introduced. The influence of background radiation and stray light on the measurement results could be reduced and suppressed by the design of thermolator and digital lock-in technique. A blackbody cavity was used as reference emission source to calibrate the system that completed absolute measurement. The spectral measurement range is 1---20 μm. The least measuring distance and the lowest power detected at the entrance pupil are 550 mm and 10^(-9) W/cm2, respectively. The experimental results show that the measure error is less than 10%.

A constrained high-order statistical algorithm is proposed to blindly deconvolute the measured spectral data and estimate the response function of the instruments simultaneously. In this algorithm, no prior-knowledge is necessary except a proper length of the unit-impulse response. This length can be easily set to be the width of the narrowest spectral line by observing the measured data. The feasibility of this method has been demonstrated experimentally by the measured Raman and absorption spectral data.

A practical neural network model was designed to realize the color space conversion of digital photofinishing. The sampling, network structure and training process were introduced respectively. But in actual training, the networks fall into local minimum in all probability. To solve this problem, evolutionary programming (EP) algorithm was applied and the learning rate was adaptively adjusted. In the experiment, the performance of network was compared with pre-optimizing. Then the color space conversion was evaluated by the simulation error of samples from the point of color difference.