Gain Characteristics And Injection Structure In Active Photonic Crystal Waveguides

Photonic crystals (PCs) as a new generation of nanostructure material have a great development in recent years owing to its photonic band gap, anomalous dispersion, and other special physical phenomenon. Active photonic crystal waveguides (PCWGs) with two-dimensional (2D) PCWGs located within gain medium, can realize a flexible adjustment of the interactions between light and matter through their anomalous dispersion effect. Thus, active PCWGs can been used to implement novel functional optical devices and their integration, which is significant for both scientific research and practical application. Based on the implementation of the National Natural Science Foundation project and 973 sub-project, this dissertation is devoted to the mode characteristics, gain and control mechanisms, as well as the electrical injection structure of active PCWGs in theory and experimental study.Mode characteristics, slow light effect, and the interaction between light and matter in active PCWGs were studied. Theory model of gain characteristics in active PCWGs with considering the natural broadening effect was presented, and the problem of infinite singular point of gain calculation at the photonic band edge is solved. Based on this, the dependence of gain maximum on the width of PCWGs was studied, and an optimized waveguide width was obtained.W3 PCWGs with a microcavity structure was proposed. Simulation results show that improved mode and gain characteristics can be obtained even in the W3 PCWGs with relative wide waveguide width because of the resonance frequency selection mechanism provided by the microcavity, which provides an effective way for optimizing the gain and mode features of the active PCWGs.Double-slots PCWGs structure formed by introducing two slots into PCWGs was proposed. Constrain of transverse current diffusion can be realized by the two slots, making carrier injection performance greatly improved. The theoretical results show that the electrical injection efficiency of double-slots PCWGs increased by about 10 times compared to W3 PCWGs. So that ultra-low loss active devices can be realized in this proposed structure. Double-slots PCWGs with air-bridge structure on silicon-on-insulator (SOI) substrate were fabricated and measured. A transmission dip with the extinction ratio of 22dB and bandwidth of 6nm was obtained for double-slots PCWG with just 21μm in length. The transmission dip in the proposed structure is 15 dB deeper than that in W3 PCWG with the same length. The measurement results verified the better mode characteristics in double-slots PCWGs. Additionally, temperature dependence of double-slots PCWGs was measured, which shows the promising applications of double-slots PCWGs on optical switchers and refractive index sensors.Inductively coupled plasma (ICP) dry etching process for III-V semiconductor materials was investigated. High aspect ratio of more than 14 for InP-based PCWGs was realized by lots of ICP deep etching experiments. The etching depth of 1.5μm was achieved for the sample with both hole radius and the slot width of 100nm. This breakthrough results on ICP etching make a solid foundation for realization of active PCWGs.