In this paper, a practical model of a thin disk regenerative amplifier has been developed based on an analytical approach,
in which Drew A. Copeland  had evaluated the loss rate of the upper state laser level due to ASE and derived the analytical
expression of the effective life-time of the upper-state laser level by taking the Lorentzian stimulated emission line-shape
and total internal reflection into account. By adopting the analytical expression of effective life-time in the rate equations,
we have developed a less numerically intensive model for predicting and analyzing the performance of a thin disk
regenerative amplifier. Thanks to the model, optimized combination of various parameters can be obtained to avoid
saturation, period-doubling bifurcation or first pulse suppression prior to experiments. The effective life-time due to ASE
is also analyzed against various parameters. The simulated results fit well with experimental data. By fitting more
experimental results with numerical model, we can improve the parameters of the model, such as reflective factor which
is used to determine the weight of boundary reflection within the influence of ASE. This practical model will be used to
explore the scaling limits imposed by ASE of the thin disk regenerative amplifier being developed in HiLASE Centre.
Here we report that the properties of the poling electrode is one of the most important factors in fabrication of the ferroelectric crystal poling. In this paper, systematic researches on the property of electrode coating and the forms of electrode contact have been made. By using pulse applied electric field, the periodically poled grating of 31.2μm was prepared on a 1mm thick 5% MgO-doped Lithium Niobate crystal. A wavelength of 1064nm pulse laser was used as fundamental source to operate optical parametric oscillation experiment, and 1.141W of idler output power was obtained when PPMgOLN pumped by 1064nm of 5.567W at the temperature of 80℃. The maximum conversion efficiency from incident pump power to the idler output achieved to 20.1%.
Periodically poled crystals are widely used as SHG, DFG, SFG, OPO and THz generation, and there is a broad application prospect in some areas such as the laser display, optical fiber communication, atmospheric exploration and military confrontation. At present, to get the parameters of periodically poled crystals, like duty ratio, the main method is chemical etching of the samples. In this paper, we present a nondestructive characterization system of periodically poled crystals. When we apply a proper high voltage on both sides of the periodically poled crystal, the refractive index difference of positive and negative domain will be increased and we can observe a clear domain pattern by the a microscope so as to obtain general information. Then a single frequency laser is prepared to radiate on +z surface of the periodically poled crystal, we can get some orders of diffraction according to diffraction optics principle. Finally, we can measure the parameters such as period, duty ratio by use of numerical analysis. The testing sample size of this system can be up to 60mm, The accuracy of the testing period can be 0.1μm, and the measurement range of duty ratio is 20%-50%.