CARS spectra of Uridine in aqueous solution are examined in the region of 900～1500 cm-1. The nonresonant background has been remarkably suppressed by using a phase mismatching method. The ring skeletal stretching modes of base, C-H bending modes and N-H bending mode can be assigned unambiguously, and the very weak vibrational modes of ribose are also oberved. The experimental conditions of the phase mismatching technique are discussed with a numerical calculation. We conclude that background-eliminated CARS measurement is a powerful tool for studying the structures of nucleic acids.

The ratio of the signal to noise of a high power laser system is the ratio of the main pulse to the noise before it. Previonsly, when a photoconductor switch and an oscillograph were used to measure the ratio of the signal to noise up to ～ 106, the oscillograph was strongly striked by the main pulse. With an improved method, same measurement result was obtained while the main pulse amplitude was greatly reduced, the measuring instrument is thus effectively protected.

Lidar measurement of wind velocity by tracking a single cloud movement was proposed.The first lidar system in Hong Kong has recently been developed.Various wind velocities unique to Hong Kong were measured under different meteorologic conditions.

The photodynamic effect of 2 photosensitizers, phycOcyanin and CPD4, on colon cancer line HR8348, was measured with MTT assay. HR8348 cells were incubated in RPMI-1640 medium containing a series of concentrations of phycocyanin(100, 50 and 25μg/ml), and subsequently subjected to an irradiation of a pulsed copper vapour laser at the wavelength of 630 nm and a fluence of 12 J/cm2. The cell survival rates were 22.1%, 37.6% and 89.7%, respectively, (P< 0.001). The survival rates of cells treated with another photosensitizer, CPD4, at the concentrations of 10, 5 and 2.5 μg/ml, were otherwise 20.1%, 25.9% and 31.5%. MTT was a speedy and handy approach for screening photosensitizers.

A new type repetition rate laser power Supply has been developed. Its main Characters and the whole quality are superior to the old laser power supply, having advantages of simple circuit,no heat source, steady operation and high stabilities of energy output and lamp waveform etc.

Spectroscopic properties and optical storage performances of spin-coated soluble metallophthalocyanine Pr4MPc/ PMMA films were studied. Pr4MPc showed different absorption spectra for the chloroform solvent and the spin-coated films. The spin-coated film based 5" disk testing showed that its reflectivity contrast C was bigger than 35% in a static optical storage testing, and the signal to noise ratio(SNR) was 40 dB in a dynamic optical storage testing.

A 8 mm wavelength Raman Free-electron Laser has been inverstigated numerically with a nonlinear theory, and its tunable ability has been studied by varying the simulation parameters. The wavelength of the FEL is variable continuously from 5 mm to 12 mm. The general behaviour of the experiment is reproduced by the simulation.

We report the first experimental demonstration that a 1.32 μm single-mode thermally stable continuous-wave Nd:YAG laser with an output higher than 2. 0 W can be obtained through simple reconstruction of an imported commercial 1.06 μm Nd:YAG laser.A brief discussion is given for further reconstruction: 1.32 μm mode-locked or Q-switched operations.

This paper shows theoretically for the first time that the starting and maintaining of the self-mode-locking of a Kerr medium self-mode-locked laser (KMSMLL) can be made more easily by rationally controlling the parameters of the detuned cavity. According to the properties of the KMSMLL such as the Kerr lens mode-locking (KLM) and the dynamic saturable Gaussian gain, using the laser ray propagational matrix, we calculated the KMSMLL numerically and obtained the most suitable detuning angle of the cavity mirror. The theory agrees with some experimental results and gives new and rational explanations.

A single longitudinal mode(SLM) pulse from a Q-switched laser, after being attenuated and slied, was injected into a Nd:YLF Q- switched slave Cavity. Its energy was amplified to 1. 5 mJ from 1. 2 nJ and its pulse width was compressed to 4. 5 us from 6 ns after amplification. A gain of 106 of the amplifier is reached. It was tested and verified by our experiments and theoretic analyses that the match of cavity lengths between a master cavity and a slave cavity was unnecessary if the pulse width of an injecting seed is shorter than a round trip time of the slave cavity. The course should be called regenerative amplification of SLM laser, not injected-locking.

In this paper, the ray path in a solid state eckige-schraube-laser is analyzed by a tensor method. The properties of self compensation for the thermal distortion and of Symmetry in x. y directions are achieved.

Some driven relaxation oscillation behaviour for a frequency shifted feedback Nd : YLF laser With long fluorescence lifetime was observed. Model calculation using rate equations for the system provides satisfactory agreement with experimental results.

A large number of polymeric materials have been investigated for their large third-order nonlinear susceptibility. Here a series of new nonlinear optical polyyne-polymers containing Pd or Ni in the main chain are described. It is decovered that the metal polyynepolymers are showed to have large X(3) value (X(3) ≌ 3 X 10-13 esu, γ ≌ 5 X 10-31 esu) and low absorption in the visible and the near infrared regions, making them potentially useful in many applications according to the results of Degenerate Four-Wave mixing (DFWM).

A concept about a new kind of nitegral photonic "transistor", using saturation absorption nonlinearity of the wead saturation optical intensity parameter of photochromic material, is put forward in this peper. A series of parallel absorption nonlinear photonic device models are constructed. Their property is studied and analysed carefully and their probable application is simply discussed.

The critical phenomena of optical bistability in two dissipative systems, i. e. the chemical reaction system and the Josephson junction, both driven externally by coherent light field, are examined by Landau (mean field) theory of phase transition in equilibrium thermodynamics. It is revealed that the critical point of bistability as an end point of firstorder-like transitions possesses the features of phase transition of second order. And the generality in the neibourhood of this critical point of these two systems with very different physical contents is illustrated also.

Recently, many experiments demonstrate that there are concentration quenching effects in Yb3+ doped solids. This paper reports a theoretical analyse, of this phenomenon. It is shown that "cooperative up conversion luminescence" is responsible for the quenching of the luminescence of Yb3+ in solids. A comparison with the experiments is given.