Silicon based photonic crystal, which inherits of the mature silicon processing technology of modern large scale integrated circuits, becomes to be the research hotspots in silicon integrated optoelectronic, all-optical communication and all-optical information processing. Based on the silicon photonic crystal waveguide (PCW), a variety of Si-based devices can be designed such as micro-cavity, waveguide, optical delay, splitter, couplers, modulators, detection and so on. In Si PCW, the slow light enhanced nonlinear is the hot spot, and had been demonstrated experimentally. In order to simulate this process, it is important to investigate the physical mechanism behind the slow light enhanced phenomena.
Prof. Sun Junqiang and Ph.D Chen Tao and Ph.D Li Linsen of WNLO have studied the mechanism. They derived the couple-mode equations for third order nonlinear effects in PCWs by employing the modal theory. The equations similar to that in nonlinear fiber optics could be expanded and applied for third-order nonlinear processes in other periodic waveguides. Based on them, one can understand the slow light enhanced phenomena, and compare the nonlinear conveniently. Moreover, after designing a slow light engineered silicon PCW. Considering the two-photon and free-carrier absorptions, the slow light enhanced multiple four-wave-mixing process had been investigated. This theoretical research also is useful for the nonlinear effects of photonic crystal structures.
This work was supported by the National Natural Science Foundations of China under Grant No. 60977044, and published on Optics Express 20(18), 20043–20058 (2012)。
Fig1. Schematic diagram of the proposed phonotic crystal waveguide