The discovery, types, mechanism, characteristics, theoretic description and experimental research development of stimulated thermal scattering are reviewed. Its applications are expected.

his work presents the lasing features of neodymium doped gadolinium gallium garnet (Nd+3:GGG ) pumped by a Xe flashlamp. Laser output energy has been measured at different pumped pulse width. The maximum output energy of f .92 J is obtained at pumped pulse width of 2 ms.

Diffractive optical elements are designed to implement the wavefront transformation from a two-dimensional circular-Gaussian beam to a two-dimensional flat-top square beam and a two-dimensional flat-top triangular beam respectively with the weighted serial iterative (WSI) algorithm, which realizes the transformation of beam-shape and the uniform distribution of the amplitude. The computed results indicate that the energy transformation efficiency is up to 95.3%, 93.6%, arid the output amplitude satisfies the need.

Non-adaptive transformations are effective in calculating the propagations of the focused laser beams. The usual non-adaptive transformation is based on the free-space propagation properties of the Gaussian beams. In this kind of transformation, the shape and the size of the Gaussian beam will be reserved, while the focused spot sizes of other kinds of beams, such as uniform wave, will increase with the increase of the focal length so that the beam will collide with the boundary of the calculation field. In this report a new kind of non-adaptive transformation is adopted in which the shrink of the calculation field will depend on the real size of the focused beams.

Nonlinear optics of low-dimensional semiconductor structures has recently attracted considerable attention. The problem is very important to the development of super-lattice devices such as fast infrared detectors and modulators because one needs to know the range of input optical intensities for which linear operation is possible. Analytical expression of the second-harmonic generation (SHG) coefficients is obtained in the Poschl-Teller well using the density matrix formalism taking into account the intrasubband relaxation. Since there are two adjustable parameters K and A in the Poschl-Teller well, the shape of the well will change with the change of the parameters K and A, accordingly the SHG coefficient will change with the parameters K and A. It is shown that the SHG coefficient depends on the parameter K , A and the tunnel bandwith. Numerical results are presented for a typical AlGaAs/GaAs Poschl-Teller well.

The differential optical absorption spectroscopy (DOAS) has become a widely used method to measure the concentration of trace gases in the atmosphere. The key to retrieving the concentration of trace gases is to get the spectrum with the fast and accurately in the DOAS system. The design and performance analysis of optomechanical scanning spectrometer is presented in this paper. It has been shown that it satisfies the demand of air quality monitoring system from the shape of calibration spectrum line and the result of measuring SO2 sample.

The HeI photoelectron spectroscopy is used not only in reseaching steady molecule but also in reseaching transient species. The system consists of a A/D card and a software to make the card to work. The system converts the analog signal (from the detector) to digital signal and processes the data in the computer. The method of designing Butterworth digital low pass filter is inteoduced in this paper. The digital low pass filter in the system improves signal-to-noise ratio.

The theoretical model of quasi-three-level system was modified through considering different lifetime of laser upper and lower level and spontaneous radiation from upper level to lower level. Numerical simulation was carried out and the law of 946 nm Nd:YAG laser performance varying with system parameters was obtained. At a certain doping concentration and output loss, there is an optimum crystal length and an optimum ratio of pump and laser beam radii. The experimental results accord with theory analysis.

The interferences owing to the defects of the grating and the stray light in the spectrometer of DOAS system cause the extra .spectral structures, which are difficult to lie distinguished from the absorption structures of the flue gas. These structures can not be removed by averaging the spectra, due to their relative stability in certain time periods. The lamp spectra taken before the light going to the polluted flue gas reflects the same instrumental structures as the spectra of the flue gas. Therefore it is very useful to reduce the noise from the optical components by dividing the lamp spectra. It is mentioned that in this case both spectra of the lamp and the flue gas should match to each other exactly in the wavelength. In order to solve these problems, two methods have been presented in this paper. It has been shown that the error of retriving the concen tration have been reduced in the experiment.

It is usual methods to use the intensity to detect the object in the optical-electricity system. But it is difficult to distinguish the object when object in clutter as the difference of the intensity between object and environment is not obvious. In this paper, the polarized characteristics of the light is used to distinguish the object in clutter. The difficulty brought by intensity can be overcome. It can be shown that this method can improve the efficient of the recognition.

Graded heterojunctions with different grading way and different doping density were analysized to show the spike at the heterojunction which can be removed or decreased to improve the performance of HB-LED. We discussed the problems that were met when we applied the double abrupt-hetero layer to fit the grading heterojunction in HB-LED.

Within the framework of the dielectric continuum approximation, the confined longitudinal-optical (LO) and interface optical (IO) phonon modes in an n-layer coupling quantum well system are deduced and discussed. To describe the vibrating of the LO phonons, a proper eigenfunction for LO phonon modes is adopted. To deal with the IO phonon modes, determinant methods are employed. The quantized LO and IO phonon fields as well as their corresponding electron-phonon interaction Hamiltonians are also derived. This work can be regarded as a generalization of some previous works, and it provides a uniform method to solve the phonon effects on the multi-layer coupling quantum well systems.

Strain buffer layer and growth interruption were applied in the QW growth by mentalorganic chemical vapor deposition (MOCVD) to improve QW photoluminescence performance. The laser diodes using the QW have very low threshold current densities (43 A/cm2) and high slop efficience (0.34 W/A, per facet).

We have successfully developed an 8 channels time division sub-carrier semiconductor DFB laser wavelength locker. We use 1 kHz sinusoidal time division electric signal and 1% AM degree to modulate every 1.55μm waveband DFB laser respectively. 2% optic signal of each DFB laser is divided into two parts, one part passing through a F-P etalon whose free spectral range is 100 GHz and another as reference signal. Optic electric differential signal of two paths feedback controls DFB lasers' temperature in order to make each DFB laser lock at the wavelength they are needed respectively. Test results show that the laser frequency spacing of wavelength-lock is 100 GHz and wavelength-lock accuracy is better than±2.5 GHz. This method can also be used in 50 GHz frequency spacing and more channels of multi-wavelength locker. This paper mainly introduces the optic and electric process and control method of the locker.

The field entropy squeezing properties in a system of vacuum of field interacting with S type three-level atom are studied. The influence of the initial state of atoms and the frequency detuning value of the mono-photon on the field entropy squeezing are discussed emphatically.

Besed upon the quantization of a mesoscopic lossless transmission line, we obtain the quantum fluctuations of the current and the voltage on inductance of the unit length line in the thermal Fock state by thermal field dynamics (TFD). The dependence of the quantum fluctuations on temperature is analysed. It is shown that the quantum fluctuations depend on not only the distribution parameters of the line, the angular frequency of the signal and the photon number, but also the temperature T.

In this paper, the field entropy evolution in the system of three-level cascade atom interacting with a single mode light field is studied by means of the quantum theory without rotating wave approximation. Compared with the result of rotating wave approximation, the influence of the virtual photon field and of the initial mean photon number on the evolution of field entropy is also discussed.

This paper studies the evolution property of the atomic information entropy squeezing in the T-C model. When the field stays in coherent light field and two atoms stay in coherent superposition state initially we solve the components of atomic information entropy precisely and calculate entropy squeezing numerically. We obtain that the atomic information entropy squeezing will change with the variation of systemic initial state, the intensity of light field and coupling coefficients.

Propagation characteristics of soliton couple in the nonlinear saturation medium are studied numerically. The results show that the nonlinear saturation in the medium intensifies the interaction of the soliton couple and shortens the length of the periods of their interaction.

Based on the optical fiber loss and by solving the modified nonlinear Schrodinger equations, the text analyses the function affected by GVD and SPM in single-mode optical fiber in negative GVD area. It quantitatively calculates the affect of soliton-effect picosecond pulse compression induced by optical fiber loss and initial orthochirp. The result shows that initial orthochirp improves the bad affect of compression factors due to the loss and stops the increase of the best optical fiber length. If an appropriate optical fiber length and initial peak power are selected, efficient compression of orthochirp pulse can be attained in single-mode optical fiber.

Based on the quantum theory, the transmission characteristics of Na, K Faraday dispersion magneto-optic filters were studied by the means of numerical calculation. The results showed that the performances of transmission changed with the different operation parameter and the zero frequency shift performance existed in suitable operating conditions.

A high precision measure method of F-P etalon spacing is proposed by measuring the moving number of transmission resonant peak with the incident angle of F-P etalon. The measurement precision of this method shows that the relative error of F-P etalon spacing will be 4×10-4 when precision of angle is 30" and optical spectrum analyzer precision is 2 GHz.

After introducing the real-time temperature measurement system using lasers In-GaAs/I and pyroelectric detector LiTaO3, this paper mainly discusses the effect and control on temperature measurement accuracy by the radiation of the detector system itself. Three measures on improving temperature measurement accuracy, cooling the detector system by water, using a narrow band filter with the bandwidth of 150 nm and making electrical compensation, are presented. Some necessary calculations and analysis are given. Experimental results also show that temperature measurement accuracy is suitable for our requirement in the range of 400℃-1200℃ after taking these measures above.