Nonlinear Optical Crystal The Cslib <sub> 6 </ Sub> O <sub> 10 </ Sub> For The Linewidth Optical Parametric Oscillator

We have carried out thoroughly theoretical the linewidth characteristic of the optical parametric oscillator (OPO) by the use of a kind of new nonlinear optical crystal- CsLiB6O10(CLBO). OPO is one of the most promising all solid state source of coherent radiation that is tunable over a broad wavelength range and high average power output with a high conversion efficiency. The application and exploitation of it has important value of not only in theory but also practicality. But the development of OPO requires the high optical quality and high damage threshold crystals. For many applications, for example, high-resolution spectroscopic studies, however, the narrow linewidth is necessary. The CLBO crystal, which has been discovered in recent years, the efficiency nonlinear coefficient is larger ,walk-off angle is smaller and permitted parametric is wider than that of BBO. We have studied and simulated the theory of linewidth of parametric light. A free-running OPO does not provide the required narrow-band radiation; however, the bandwidth can be reduced considerably by use of intracavity elements such as prisms and gratings or by etalons with a narrow-band laser on either the signal or the idler wavelength.In the sectionl, we introduced the development of OPO and the correlative nonlinear optical (NLO) crystal, summarized the background and the recent advance of the CLBO and linewidth of OPO; In the section2, we have studied and stimulated linewidth of parametric light of CLBO optical parametric oscillators pumped by 355nm by computer. We presents a detailedstudied of the linewidth of parametric light in CLBO-OPO caused by the linewidth of pumping beam, off axis phase matching, divergence angle of pumping, time above threshold, high gain coefficient of NLO crystal, fluctuate of cavitylength, spontaneous radiation, according to the momentum and energy conversion laws, and the Sellmeier equations of the CLBO, We calculated curves of the type -I and type -II compared with the BBO's. It is shown that the divergence angle of pumping beam and off axis pumping and spontaneous radiation influenced the linewidth of parametric light more quickly than those of other factors did , and the linewidth of parametric light is very narrow far away from the degeneracy point ,and the linewidth begins to large quickly at the degeneracy point. We got the conclusion that the linewidth of CLBO is higher than that of BBO at the same condition. In sections, we reduced the linewidth of parametric light considerably by use of the elements such as prisms and gratings or by etalons. We can obtain the linewidth less 2nm, less O.Snm, less 0.06nm, respectively.