We identified the amplified spontaneous emission-amplified spontaneous emission (ASE-ASE) beat noise from the semiconductor optical amplifier, which has been overlooked in previous studies, as a cause of severe system penalties when it was used to provide single-channel amplification in a dynamic central office environment through experimental studies. Our results pointed out that the ASE-ASE beat noise of the optical amplifier, other than its gain and noise figure, has to be considered to correctly predict its performance in these new applications.

A novel integrated dense wavelength division multiplexing interleaver scheme is presented based on phased-array (PHASAR) wavelength demultiplexer with multimode interference (MMI) couplers. MMI-PHASAR interleaver with simple structure and compact size can realize narrow channel spacing through simple design procedure. And it is convenient for integration with integrated planar waveguide multiplexer/demultiplexers. A 25/50-GHz MMI-PHASAR interleaver is designed and the transmission characteristic is investigated by beam propagation method.

An experiment of two-stage adaptive compensation for polarization mode dispersion (PMD) in a 40-Gb/s optical time-division multiplexed communication system is reported. The PMD monitoring technique based on degree of polarization was adopted. The particle swarm optimization (PSO) algorithm was introduced in adaptive PMD compensation. The comparison was made to estimate the effectiveness between PSO algorithms with global neighborhood structure (GPSO) and with local neighborhood structure (LPSO). The LPSO algorithm is shown to be more effective to search global optimum for PMD compensation than GPSO algorithm. The two-stage PMD compensator is shown to be effective for both first- and second-order PMD, and the compensator is shown to be bit rate independent. The optimum searching time is within one hundred milliseconds.

Correlated perturbations caused by both randomly varying birefringence and random dispersion map are considered in optical time division multiplexed dispersion-managed dark soliton system, and their effects on soliton interaction are investigated numerically. These perturbations enhance soliton interaction, and their effects relate to the strength of perturbation, separation, and pulse width. The correlation plays an important role and reinforces these effects. Moreover, there is a stochastic limit between two perturbations in the system, where the effect is the largest and the corresponding interaction distance is the shortest.

This paper presents vehicle detection and tracking algorithms based on real-time background (RTB) and phase-correlation (PC) in the video sequence of urban highway with fixed camera. Firstly moving objects are obtained by subtracting RTB from serial images. After classification, PC is used to determine corresponding regions of moving objects between consecutive frames. The problems of vehicles' merging and splitting, sudden stop, and restart are also considered. Experiments show that the method is practical and can realize real-time detection and tracking of vehicles on highway.

This paper proposes a new multispectral image data compression algorithm (KLT/WT-3DEZB). The proposed coding strategy consists of three main steps. Firstly, a wavelet transform (WT) is applied to reduce the spatial redundancies. Then, a Karhunen-Loeve transform (KLT) is used to reduce the redundancies in the spectral domain. Finally, a modified SPECK algorithm---three-dimensional embedded zeroblock (3DEZB) algorithm is proposed and used to encode the transformed coefficients. Numerical experiments show that the reconstructed images using the proposed algorithm exhibite a better quality and a higher compression ratio than those obtained by traditional KLT/WT-3DSPIHT, 3DSPIHT, and 3DSPECK algorithms.

The phenomenon of stochastic resonance (SR) is found in a single-mode laser system driven by the colored pump noise with signal modulation and the quantum noise with cross-correlation between the real and imaginary parts. When the net gain a0 changes, it is found that, 1) the shape of the curve of the signal-to-noise ratio (SNR) versus the pump noise self-correlation time \tau exhibits a changing process of multiform SR, from single-peak SR to simultaneous existence of resonances and suppressions; 2) the curve of SNR versus signal frequency \Omega experiences a complicated changing process from the monotonous descending to the simultaneous appearances of a maximum and a minimum, and finally to monotonous descending; 3) the curve of SNR versus cross-correlation coefficient between the real and imaginary parts of the quantum noise \lambda_(q) appears an acute single-peak SR. Therefore, the net gain a0 greatly influences the characteristic of SR of laser system.

The frequency stability of an all-solid-state Nd:YVO4 laser is significantly improved by means of a specially designed Fabry-Perot (F-P) interferometer used for the frequency standard in the frequency-stabilizing system. The temperature of the F-P cavity is accurately controlled by a set of thermoelectric cooler (TEC) modules attached on the body of the cavity and the electronic feedback circuit. We find that the long-term unidirectional frequency shift of the output laser, resulting from the slow increase of the cavity length under the effect of the temperature integration on the cavity body, is essentially eliminated. The frequency stability of the output laser with the power of 530 mW is better than +- 200 kHz in 1 minute and +- 2.3 MHz in 40 minutes, respectively. The fluctuation of output power is smaller than +- 0.5% over one hour.

At liquid-nitrogen temperature, at 10-kHz pulse repetition rate, Q-switched 36-ns pulses with average output power of 4 W at 2.05 um and 4.5-W continuous wave output power with a total optical-optical conversion efficiency of 30%, were achievedfrom a 6% Tm, 0.5% Ho:YLiF4 laser. This laser was end-pumped by a fiber-coupled laser diode emitting up to 15 W around 792 nm. The 1-m-long optical fiber carrying the pump radiation has a core diameter of 700 um with a numerical aperture of 0.22.

The magnetization-induced nonlinear optical and nonlinear magneto-optical properties in a magnetic metal-insulator composite are studied based on a tensor effective medium approximation with shape factor and Taylor-expansion method. There is a weakly nonlinear relation between electric displacement D and electric field E in the composite. The results of our studies on the effective dielectric tensor and the nonlinear susceptibility tensor in a magnetic nanocomposite are surveyed. It is shown that such a metal-insulator composite exhibits the enhancements of optical and magneto-optical nonlinearity. The frequencies at which the enhancements occur, and the amplitude of the enhancement factors depend on the concentration and shape of the magnetic grains.

In optical scattering particle sizing, a numerical transform is sought so that a particle size distribution can be determined from angular measurements of near forward scattering, which has been adopted in the measurement of blood cells. In this paper a new method of counting and classification of blood cell, laser light scattering method from stationary suspensions, is presented. The genetic algorithm combined with nonnegative least squared algorithm is employed to inverse the size distribution of blood cells. Numerical tests show that these techniques can be successfully applied to measuring size distribution of blood cell with high stability.

Phase-matched high-order harmonic generation in Ar gas-filled cell is investigated experimentally. We obtain phase-matched 27th order harmonic driven by a commercially available solid-state femtosecond laser system at 0.55 mJ/pulse energy level and 1-kHz repetition rate. Moreover, we find that the spatial distribution of intensity of high-order harmonics is flat-top profile other than a Gaussian one under the condition of optimized conversion efficiency in the static gas cell.

The principle of broad-band orthogonal-pump (BOP) four-wave mixing in semiconductor optical amplifiers is analyzed in theory. The conversion efficiency reduces rapidly as the detuning of wavelength between the signal and pump increase which can be solved by introducing a BOP method. The constant conversion efficiency and signal-to-noise ratio are obtained over a large wavelength detuning range. The wavelength conversion efficiency with variation smaller than 3.88 dB over 52-nm range has been experimentally demonstrated by using BOP, with the 10-GHz output of distributed feedback/electro-absorption modulator as signal. Conventional single-pump scheme is also performed for comparison and the experimental results fit well with the theory.

The spectral resolved femtosecond pump-probe experiment is applied to measure the third order nonlinear refractive index coefficient, two-photon absorption coefficient of GaP crystal, and the chirp parameter of the input laser pulses. The results show that nonlinear refractive index coefficient is 2*10^(-18) m2/W, two-photon absorption coefficient is 2*10^(-11) m/W at wavelength of 783.5 nm, and the chirp parameter of laser pulse is 1*10^(25) s^(-2). Furthermore, the mechanism of nonlinear refraction due to two-photon absorption in GaP crystal and experimental results are discussed.

A kind of novel broad-band superluminescent diodes (SLDs) using graded tensile-strained bulk InGaAs is developed. The graded tensile-strained bulk InGaAs is obtained by changing only group-III trimethyl-gallium source flow during low-pressure metal organic vapor-phase epitaxy. At the injection current of 200 mA, the fabricated SLDs with such structure demonstrate full-width at half-maximum spectral width of 106 nm and the output light power of 13.6 mW, respectively.

A four-channel 400-GHz spacing flat focal field arrayed waveguide grating (AWG) demultiplexer is designed based on polymeric optical waveguide. The waveguide core-layer material is a newly developed negative tone epoxy Novolak resin (ENR) polymer with ultravoilet (UV) cured resin Norland optical adhesive 61 (NOA61) as the cladding layer. The device is fabricated using electron-beam direct writing, which has less processing steps than the reported polymeric AWGs. The experimental result is presented.

ZrO2 thin films were prepared in electron beam thermal evaporation method. And the deposition rate changed from 1.3 to6.3 nm/s in our study. X-ray diffractometer and spectrophotometer were employed to characterize the films. X-raydiffraction (XRD) spectra pattern shows that films structure changed from amorphous to polycrystalline with deposition rate increasing. The results indicate that internal stresses of the films are compressive in most case. Thin films deposited in our study are inhomogeneous, and the inhomogeneity is enhanced with the deposition rate increasing.

A double sinusoidal phase modulating (SPM) laser diode interferometer for thickness measurements of a transparent plate is presented. A carrier signal is given to the interference signal by using a piezoelectric transducer, and the SPM interferometry is applied to measure the thickness of a transparent plate. By combining the double-modulation technique with the Bessel function ratio method, the measurement error originating from light intensity fluctuations caused by the modulation current can be decreased greatly. The thicknesses of a glass parallel plate and a quartz glass are measured in real time, and the corresponding experimental results are also given.

A superlattice-like (SLL) structure was applied to phase-change optical recording. The recording layer consisting of alternating thin layers of two different phase-change materials, GeTe and Sb2Te3, were grown by magnetron sputtering on polycarbonate substrates. Land/groove optical recording was adopted to suppress crosstalk and obtain a large track density. Dynamic properties of the SLL disc were investigated with the shortest 1T pulse duration of 8 ns. Clear eye pattern was observed after 10000 direct overwrite cycles. Erasability above 20 dB was achieved at a constant linear velocity of 19 m/s. Carrier-noise ratio (CNR) kept above 46 dB when the recording frequency reaches 21 MHz. The SLL phase change optical disc demonstrates a better recording performance than the Ge1Sb2Te4 and Ge1Sb4Te7 discs in terms of CNR, erasability, and overwrite jitter.

It is important to predict the intensity distribution in focusing plane for designing the X-ray compound refractive lenses. On the basis of analyzing the structure of X-ray compound lenses and comparing it with Fraunhofer diffraction system, it is concluded that the X-ray focusing system can be regarded as a kind of Fraunhofer diffraction system. Therefore, a method based on Fourier spectrum analysis is presented to predict the intensity distribution in the focusing plane for the X-ray lenses. A brief analysis on the relationship between the parameters of X-ray lenses and their focusing performance is also given in this paper.