光参量振荡器阈值的研究

为获得光参量振荡器（OPO）的高效率运转,尤其是在小功率泵浦的情况下,降低它的阈值成为研究的重要内容。通过分析影响OPO阈值的因素,得到了通过以下手段来降低阈值的方法：选择有效非线性系数大的晶体,选择满足走离条件下较长的晶体,增大泵浦光与信号光模式匹配因子,双程泵浦,短的OPO的腔长和泵浦光脉冲,降低信号光在腔内往返损耗,选择合适的输出镜强度反射率等。并重点对影响阈值因素中的泵浦光与信号光模式匹配因子进行了研究,得到了双凹腔结构腔内任意位置的模式匹配计算的一般方法,当腔镜曲率半径趋于无穷时,该结果可以过渡到平平腔或平凹腔的特殊结构,并在实验上实现了小功率腔内OPO的运转。

The study of the threshold for optical parametric oscillator

In order to obtain the high efficiency operation of optical parametric oscillator（OPO）,it is very important to decrease the threshold of OPO especially for the case of low power pump.The ways of decreasing the threshold are obtained by studying the factors which affected threshold.The ways include choosing crystal which has bigger effective nonlinear coefficient,choosing longer crystal when walk-off being satisfied,increasing mode matching factor of pumping and signal beam,double-way pumping,choosing shorter cavity of OPO and choosing shorter pumping pulse width,decreasing loss of signal light in the cavity,choosing proper reflectivity of the output mirror etc.And the importance of study is placed on the mode matching of the pumping and signal beam.The general calculating method of mode matching in any place of the double-concave cavity is derived.When the radius of curvature of the cavity mirror is infinity,the results will transform to plano-plano or plano-concave cavity.And low power intra-cavity OPO is realized at last.