In this paper, an experimental sot-up of colliding pulse mode locking of a Nd:YAG laser is reported. The effect of various parameters on the characteristics of colliding pulse mode-locking was investigated. Under the optimal condition, the shortest pulse duration of 8 ps was obtained and the stability of output energy was about ±7%.

Reflection spectra of resonant reflectors have been solved on a computer. They can be divided into two types: degenerate and non-degenerate. Line shapes of resonant peaks, modulability of envelopes, characteristics of periodic spectra and two relevant properties are discussed in detail. The single axial mode operation in a tuning range of 2A has been obtained with a PZT tuned resonant reflector. This work provides a background for designing resonant reflectors.

In addition to pboto-elastic effect, we have also considered rotation and electro-optic effects in calculating Brillouin tensors of LiNbO3 crystals. After careful design and adjustment of the experiment system. Brillouin spectra of LiNbO3 crystals were measured in the 90° scattering scheme. We measured all independent elastic and piezoelectric constants of LiNbO3 crystals made in China in the hypersonic region. The spatial were also measured in the 180?back scattering scheme. Experimental results are in good agreement with calculations.

The photoluminescence (PL) technique at liquid helium tempera-ture has been applied to characterization of shallow imparities and thermal defects in silicon crystals. A number of PL spectra of B-doped and P-doped Sj with different doping levels have been obtained together with quantitative analysis. A concentration of boron as low as 5×1011 cm-3 in highly pure Si could be detected. The dependence of PL intensity on excitation intensity was investigated. We have also applied the PL technique in the analysis ...

Experimental results of electron interference and Fresnel diffraction observed on a transmission electron microscope using an electrostatic biprism as beam-splliter are reported.

The exact analytic and steady-state solutions are derived for high-order Gaussian beam propagation modes in media with quadratic radial refractive index and gain (loss) profiles based on the slowly varying envelope approximation (SVEA). Explicit expressions of the solutions are given for some useful specific cases. Possible applications of the present theory to optical cavities and waveguides with such media and to problems of optical bistability in cavities having media with quadratic radial index and absorption profile are discussed.

The first-order perturbation theory is used to analyse the propagation characteristics of guided modes on fiber-core spliced section. The results are applied to determine the theoretical coupling amount of monomode optical fiber directional coupler with strong transverse coupling by means of the mode excitation theory. Our theoretical results are in good agreement with the experimental measurements.

Effects of central dip in refractive index on the normalized cut-off frequency, normalized propagation constant, dispersion and power distribution of W-type single-mode fibers have been studied in detail.For typical W-type single-mode fibers, propagation characteristics will not show significant changes provided the width and depth of the central dip are less than 50%.

Lamb s quantum theory of lasers is extended to deal with the three-mode laser operation in an in homogeneously broadened solid medium consisting of four-level atoms. The master equation, the operation characteristics and the line-width of the three-mode laser are obtained and discussed. The relevant experimental result is explained and effects of inhomogeneous broadening are studied.

This paper describes the characteristics of six laser dyes of PBD series which are compounds of 2-phenyl- and five of 2-(p- or m- substitued phenyl)-5-(4 -biphenyl-yl oxadiazoles. Two of them are new compounds that were synthesized by Nankai University. The ultraviolet absorption spectra, fluorescence spectra and fluorescence quantum yields of such dyes are given. Tuning curves of PBD dye lasers pumped by a nitrogen laser are measured, and the tunable spectral regions are found to be of 356 to 393 nm. The laser conversion efficiencies of all the six PBD dyes reported here are higher than those of existing laser dyes of PPO and BPBD. The PBD series dyes are suitable to be pumped by either N2 laser (377nm) or XeGl excimer laser (308nm).

Reducing carrying frequencies in computer generated holograms ia very important in constructing the graphs. We propose a new off-axis filtering method in the space domain, which is suitable for wavefronts with quadric term. In some cases, by using this method the carrying frequency can be reduced to about 1/3 of that used in conventional frequency domain filtering. Two sets of preliminary experimental results are shown.

The principle and method of shearing interferometric testing of the major mirror of an astronomical telescope with aperture of 1.56m are described in this paper. Measurement results with 1/4 PV are obtained.

Stimulated emission based on two-step hybrid resonance via A1∑u or B1∏u state of Na2 has been observed by using a broad-band and a narrow-band dye laser as pumping sources. The maclunism is discussed.

Population inversion between Ar+ 4p and 4s levels was detected in the direct current hollow cathode discharge (HOD) of pure argon by laser-induced fluorescence measurement. Experimental data were obtained and analysed.

In this paper some techniques for measuring stress, absorption, scattering and other properties of thin films are described. The properties of some oxides and films doped withoxides are measured by using these techniques. Auger electron spectroscopy and X-ray diffraction technique are employed to analyse chemical compositions and crystal structures of films. Some useful results have been obtained.