In this paper, the basic principles, schemes, characteristics and their recent developments and applications of magnetic traps are reviewed in detail. All these magnetic traps can be divided into three kinds: macroscopic static magnetic trap, microscopic static magnetic trap and microwave or ac magnetic trap, according to the sizes of magnetic-trap devices, the characteristics of magnetic wells and the methods of generating magnetic fields. Finally, some recent applications of magnetic traps in the experiments of Bose-Einstein condensation (BEC) and atomic chip are briefly introduced.

In this paper, we describe the advantages and key technologies of free-space laser communication. At the same time, the developments of laser communication domestic and aboard are described.

The two-mirror systems which are convergent and comply with |a| < 1 are discussed based on the third-order aberration theory. A general analysis on zero-coma system and zero-astigmatism system with the initial condition of zero-spherical aberration are figured out. The variety of the vertex radius of curvature R1, R2 and surface figure of primary mirror and secondary mirror with obstruction ratio a and amplification β with different aspheric coefficient are analysed. The classic systems which consisted of two mirrors are summarized.

Six optical microcavities with different refractive index distribution are studied using the finite-difference time-domain method (FDTD). The energy distribution and quality factors of different radial-order whispering-gallery modes are calculated. The effect of step-index distribution and graded-index distribution are analyzed. Then the methods of enhancing certain modes and improving microcavity performance are also discussed. These results provide reference for the further study and application of optical microcavity.

Nonlinear optical rectification in a special asymmetric parabolic quantum well is studied by density-matrix methods, and the analytical expression of optical rectification coefficient is derived. Finally, the numerical results are presented for a typical GaAs/AlGaAs asymmetric quantum well. The variation rules between rectification coefficient and the asymmetry of quantum well, the incident photon energy are obtained. The larger rectification coefficient was obtained in this special quantum well. This is a feasible way to get fine nonlinear materials in experiment.

By microwave discharge of the mixture of N2 and O2, water vapor and air, the NO+ and H3O+(H2O)n which originally exist in the earth's ionosphere were produced. The dynamics analysis indicates that these ions in the atmosphere are formed by the ion chemistry of the primary ions produced through the cosmic radiation of the air reacting with electrons, atoms and molecules surrounded them. This conclusion has also simulated the formation process of these ions. At the same time, the figures of the mass spectra of the microwave discharge of the mixture of N2, O2 the water vapor and air were also presented.

A novel advanced approach to continuous-wave cavity ring-down spectroscopy (CW-CRDS) based on a rapidly swept cavity is described, in which an optical cavity with super-high reflectivity cavity mirrors is used as a gaseous species pool of absorption spectra. The cavity is swept by PZT at 4 Hz repetition rate to shift the frequency of optical radiation stored in the cavity. A continuous-wave tunable diode laser frequency is synchronously scanned over a small range (-1 cm-1) at a low repetition rate. The transmitted cavity mode peaks are recorded. Absorption spectrum data is extracted from the envelope of the transmitted cavity mode peaks. High sensitivity absorption spectra of low CO2 content of 0.5 mbar near 6537 cm-1 and the weak absorption band (-10-27 cm-1/(molecule- cm-2)) near 6577 cm-1 were recorded using the novel scheme. The detection sensitivity is much higher than that of traditional absorption spectroscopy technique. It provides a novel, high-sensitivity, effective method for absorption spectrum measurements and microanalysis of gaseous species.

The principle of a differential optical absorption spectrometer (DOAS) is presented in this paper. UV-VIS light that emits from a high-pressure arc lamp is collimated by the telescope, reflected by the retroreflector, collected by the same telescope. In the transmission, different gases have different absorptions in different wavebands which can distinguish the different gases, and the spectra have carried the characteristics of air pollutants, so we can retrieve the concentration of air pollutants by comparing the measuring spectra and the lamp spectra. We use this method to measure the organic pollutants. In processing and analyzing the spectra, we use some mathematics algorithm, such as the polynomial of specified degree, least squares fitting algorithm, etc, so the concentration can retrieve precisely. In this paper, we use DOAS method to measure the spectra of benzene and toluene sample and analyze the results. The results anastomose with the theory. The method will be the reliable one for measuring and monitoring the atmosphere organic pollutants.

In this paper, a diode laser end-pumped continues-wave polycrystalline 1% Nd:YAG ceramic laser at 1.32μm is demonstrated. The lasing threshold is 2.1 W. With an incident pump power of 9 W, an average output power of 690 mW is achieved. The slope efficiency is 11%. To our knowledge, it is a 1.32μm Nd:YAG ceramic laser with a maximum output power which has been reported at present.

A LD pumped intra-cavity Q-switched Nd:GdVO4/KTP green laser is reported in this paper. When the incident pump power is 7 W, the average power of 109 mW, repetition rate of 40 kHz, pulse width of 30 ns and peak power of 91 mW are obtained.

In this paper, the absorption, emission spectra, and the energy-level structure of Yb:YAG crystal are introduced. The thin disk laser consists of Yb:YAG rod, 940 nm InGaAs LD pump source with the maximal output power 15 W, coupling system, heat sink, and a front cavity mirror. Using an end-pump configuration, the output characteristic of the all-solid thin disk laser is studied. Its maximal output power of 1030 nm is 2.1 W under 14 W pump power, with the optical-optical and slope efficiency of 15% and 24.3%, respectively.

In this paper, a simple model of optical guide is investigated and the quantum-mechanical dynamics of cold atoms in the optical guide formed by a large red-detuning Gaussian laser beam is calculated. From our simulations, we can conclude that the bigger the laser detuning and the lower the laser intensity we use, the longer the guiding length we can obtain.

In this paper, a way of chaos secret communication based on parameter modulation is proposed. Our study shows that after parameter modulation some characters of the output of AOB chaos system are still kept, the time sequence of chaotic output still has continuous power spectrum, and looks like a random output. So information could be hid in the sequence. Computer simulation has also proved that secret communication with parameter modulation of AOB chaotic system is feasible. We have also studied influence factor of this system and their effects on secret communication.

The time evolution of atom's occupancy in the system of two coupling atoms interacting with two-photon in Kerr medium is studied by means of quantum theory. The influences of the atomic initial state, the initial squeezed parameter r and coupling constant X are discussed.

In this paper, the evolution of the occupation probability in the system of two two-level atoms interacting with a single mode light field in the Kerr medium is studied by C-RWA. The influences of Kerr effect and virtual photon field effect on the occupation probability are also discussed. It has been shown that the quantum noise appears under C-RWA;the quantum noise becomes weak while ω increases: the amplitude of Rabi oscillation decreases while g increases, and the occupation probability of initial state increases while μ increases.

A novel data processing method to improve the interference metric precision of laser beams based on improved genetic algorithms (GAs) is presented. The improved GAs to fit curves is compared with the conventional GAs and the conventional least square method to fit curves. Using the improved genetic algorithms, the results show that the influence on the precision of measurement from errors in quantitating the size of image element of CCD and on the image-gathering cards in CCD optic interference measurement is removed, and that the multi-extremum of object function is resolved. The location precision of interference stripes is also increased, and the intensity distribution of the stripes is fitted accurately. The error of curve fitting is also discussed . GAs is shown to be very well in possession of robustness and adaptability.

Under the effective mass approximation, the energy levels for the bound states of electron and hole in a quantum dot quantum well (QDQW) system are investigated. Numeral calculations on CdS/HgS and ZnS/CdSe QDQW are performed. Results reveal that the curves of the dependence of the eigen-energy on the size of the QDQW have some yielding points, which is obviously different from that in homogenous quantum dot, and the intervals of energy levels for electronic states in CdS/HgS QDQW have maximum at some certain quantum numbers n, while those for hole states in ZnS/CdSe QDQW increase monotonously, it is due to the difference of the ratios of the effective mass of the materials synthesized the QDQW.

In the present paper, two types of strained InGaAs/AlGaAs multi-quantum wells grown by MOCVD were designed, in which the thicknesses of quantum wells were 3 nm and 6 mn, respectively. The PL peak wavelengths were measured to be 842 nm and 942 nm, respectively. The shift of energy band in the InGaAs/AlGaAs MQWs due to the quantum size effect, and the strain effect in the active layers was calculated with the theory of the finite quantum well, and the shift of the PL peak wavelengths was also interpreted.

This paper, based on diffusion theory of crystal-lattice atoms , analyzes the diffusion laws of III & V family atoms in the InGaAsP semiconductor material . The theory model of quantum well intermixing (QWI) in quantum wells and super-lattice are established. The relations of component material and strain with diffusion length are computed by simulation , and the strained effects to quantum wells band-gaps, band-edge structures and quantum jump are computed and analyzed. Some valuable results are obtained which supply the principal theoretical basis for researching and developing quantum wells and super lattice devices.

We investgated the oxidation behaviors of Si1-xGex alloys with 0.5%, 2%, 5%, 15% and 25%) Ge content. The oxidation of SiGc films with different compositions was carried out in dry oxygen gas at 800℃, 900℃ and 1000℃ for various length of time. Thickness and property of nanoparticle and nanolayer in oxide films and germanium segregation in oxidation of SiGe alloys obtained using high precision ellipsometer (HPE) showed good agreement with Rutherford backscattering spectrometry (RBS), profile dektak instrument (PDI) and high-resolution scanning transmission electron microscopy (HR-STEM) observation. We observed that the Ge content in the oxide layer increased with the Ge content in SiGe layers, Ge content in the oxide film decreased with the increase of oxidation temperature and with the increase of time length. Rejection of Ge resulted in piling up of Ge at the interface between the growing SiO2 and the remaining SiGe which formed nanometer Ge-rich layer. And substantial interdiffusion of Si and Ge took place in the remaining SiGe which led to the complicated distribution of Ge segregation.Several new phenomena were discovered,and the experimental results were dicussed and simulated.The oxidation optimum of SiGe has been obtained.

The analysis of the image quality on focus plate is very important in infrared seeker measurement. As for auto-focusing system, image manipulation is critical preparation, and choosing focusing function is the core technology. How to process image and the widely-used principle of various focus arithmetic is discussed. Traditional climbing real-time searching is improved in practical application because Visual C++ is not good enough in controlling. In this way, higher speed, precision and repetition are accomplished.

In this paper we designed and made the sprayer, the water mist field characteristics produced by the sprayer were measured by the LDV/APV system. On the basis of the measurement, the experiment of extinguishing liquid fuel flame by the water mist was made. The temperature of the flame area was measured by thermocouples and infrared thermography before and after the application of water mist. The experimental results show that it is feasible to apply in water mist fire suppression, which has better characteristics.

The experiment took place during June 1999 at the East Sea in China using the radiosondes developed by us, which measured vertical profiles of atmospheric pressure, temperature, relative humidity and the refractive index structure parameter C2n. The diurnal variation of temperature is less than 3℃ above sea surface up to 800 m, the surface-based nocturnal inversion is weak. The atmosphere temperature on sea surface decreases 1℃ when latitudes increase 1 degree. The measured profile shows the rapid falloff of C2n from the surface to the relatively quiet about 500 m height. The C2n appears constant with altitude from 500 m to 2000 m height. The measured and modeled profiles of potential temperature have been compared.

In need of study of atmospheric convective boundary layer(ACBL) in laboratory model , we developed a set of equipments used for measuring temperature and velocity field in water. Single-probe sensor made of copper was used for measuring mean temperature, and multi-probe sensor made of platinum was used for measuring temperature fluctuation . These sensors can be moved by motors. Microparticles illuminated by a laser light sheet and particle tracing velocimetry (PTV) technology were used for measuring velocity. Response of these equipments is fast, and resolution is high, so the laboratory model can be provided with reliable experimental methods. From the measuring results, the structure of the laboratory model of ACBL, especially of entrainment zone, can be studied at large. The measurement errors of temperature and velocity and their estimation were also analyzed. The error of measuring temperature mostly came from random error, and the random error is about 0.005℃. The error of measuring velocity mostly came from systematic error .How to decrease error was prosposed in the paper.