The majority of known tunable UV sources were complicated devicescomprising some tunable laser in visible region and subsequent nonlinearfrequencyconversion.
以前的可调谐紫外激光器是基于可见光区域的可调谐激光，经过非线性频率变换得到。 结构复杂、可靠性差。
2
The optical characteristics of nonlinear optical crystals, especially several common mid-IR nonlinear crystals have been introduced in the research of nonlinearfrequencyconversion crystals.
In nonlinear optical frequencyconversion process, it is desirable to maximize the product of the intensity of pump laser and the interaction length in order to achieve maximum conversion efficiency.