相匹配契伦可夫辐射式倍频

用波导产生倍频波时,如果倍频波进入辐射模区,仍然有相匹配问题。契伦可夫辐射式倍频不是自动地实现相匹配的。相匹配要求导波基波模式场,倍频传输场(自由波),倍频触发场,以及经多次反射透射后的辐射场的迭加形成的总辐射场处于同步的相匹配状态。根据这个相匹配的分析,提出波导契伦可夫相匹配的特有的方法,那就是对波导的模色散进行设计,并指出非对称波导的特有优点,是改变一个边界上的反射相变,即选择不同色散的线性材料作包层,由此可得到相匹配的高效契伦可夫倍频辐射。

Phase matching Cerenkov radiation type SHG

Guided wave second-harmonic (SH) generation can not be phase matched automatically by Cerenkov radiation scheme. There is still phase-matching condition to be satisfied in case of the SH generation in radiation mode of the waveguide. The phase matching condition is so critical that all the fundamental wave (the driving source), the generated SH wave, and the free SH wave multiply reflected and transmitted across the boundaries of the waveguide have to keep in phase. This kind of phase matching can be obtained by typical waveguide technique, i.e. to change the boundary condition. With the unsymmetrical slab waveguide scheme, phase matching can be achieved by simply changing the cover material with different index. The formula is given.