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The basic optical property and phase-matching of new mixed AgGaGeS4 crystal are presented. Frequency conversion, in particular the SHG of 30ns pulses of 9μm emission band of transversely excited atmospheric-pressure (TEA) CO2 laser, is realized in AgGaGeS4 for the first time. As high as 0.57% peak power and 0.3% external energy efficiencies and 0.7mJ harmonic pulse energy are obtained for the 9.55 μm emission line at pump intensity of 4% level of the damage threshold.

As a continuation and extension of "quantity in phase space" "quantity in quantum space" is introduced. With that, the disappearing of quantum interference discussed in a previous paper [S. Durr, et al., Nature 395 (1998) 33] is explained in the same spirit as our recent papers [Ren De-Ming, Commun. Theor. Phys. (Beijing, China) 41 (2004) 685, 833]

Using Mie theory, we studied influences of organic films for bubbles on optical scattering properties of ship wakes. Contributions of them to scattering properties relate to the thickness and refractive index of them.

For the nonlinearity of Fabry—Perot interferometer (FPI) transmission spectrum, the measurement uncertainty of incoherent Mie Doppler wind lidar based on it increases evidently with the increase of backscattering signal Doppler shift. A method of repeating the use of the approximate linear part of FPI transmission spectra for reducing the high uncertainty of a big Doppler shift is proposed. One of the ways of realizing this method is discussed in detail, in which the characteristics of FPI transmission spectrum changing with thickness and incident angle are utilized simultaneously. Under different atmosphere conditions, it has been proved theoretically that the range of measurement uncertainty drops to one-sixth while its minimum has no serious change. This method can be used not only to guide the new system design, but also as a new working way for the fabricated system.

The delay theoretical analysis result of single-longitudinal-mode pulse injected in active Fabry-Perot cavity has been obtained. The gain in Fabry-Perot cavity has been calculated and the numerical simulation result of output pulse has been obtained. The results show that when the energy of the pulse decreases at a certain value, the gain produced by increased pump particle population can compensate the loss in the cavity and the delay pulse can achieve steady state. In experiment, the active Fabry-Perot cavity is a Nd: YAG laser sided pumped by laser diode. For the pulse inputed externally, we achieve 140 pulses within 2 ups. Finally, the reference light is delayed using the active Fabry-Perot cavity. And we show the heterodyne experiment of signal light whose frequency shift generated by an acousto-optic modulation (AOM), and the experiment results accord with the frequency shift of the AOM and the error is less than 4%.

The linear and nonlinear optical properties,as well as phase-matching of mixed Cd0.35Hg0.65Ga2S4 nonlinear crystal are investigated. Da mage threshold is determined in comparison with the widely used middle IR crystal under identical experimental conditions. CO2 laser second harmonic generatio n (SHG) is realized in this crystal at a phase-matching angle in well coi ncidence with estimation.