A Two-Dimensional Nonlinear Photonic Crystal with a Rectangular Loop

A novel model of two-dimensional periodically poled lithium niobate designed for second harmonic generation of 1064 nm is proposed, in which a rectangular light route is used. The effective length of the sample is longer than the sample real length by 5/3 2^1/2 times. The conversion efficiency enhances greatly without prolonging the periodically poled crystal length.