Nonlinear Optical Effects in One Dimensional Multi-layer Structure Consisting of Polar Ferroelectric Called LiTaO3

The transfer matrix method has been widely used to calculate the scattering of electromagnetic waves. In this paper, the second harmonic generation in finite size one- dimensional periodically poled LiTaO3 has been investigated. To calculate the conversion efficiency, fundamental and second harmonic wave propagation among proposed structures, we use the transfer matrix method. In the designed nonlinear photonic crystal structure, the linear and nonlinear optical parameters are both periodically modulated, and thus the second harmonic generation efficiency can be several orders of magnitude larger than in a conventional quasi-phase matched nonlinear structure with the same sample length. The reason is that, due to the presence of photonic band gap edges, the density of states of the electromagnetic fields is large, the group velocity is small (as a result, the interaction time is increased), and the local field is enhanced. All three factors contribute to significant enhancement of the nonlinear optical interactions.