Simulation of Gap Structure Optical Waveguide with Phase Change Materials.

Optical phase change material (O-PCM) have attracted extensive attention due to its large change in optical properties between phase transitions. Its application in rewritable non-volatile photonic devices is extremely interesting except the drawback of moderate loss induced by the O-PCM. In this work, a "gap" structure waveguide device with an O-PCM layer is proposed to simulate the optical propagation in both amorphous and crystalline state. The effective refractive indices (neff), losses (a) and figure-of-merits (FOMs) are obtained by simulations for Ge2Sb2Te5 (GST), GeS, Sb2S3, Sb2Se3 and Ge2Sb2Se4Te (GSST). The results indicate the "gap" structure have effectively mitigated the propagation loss induced by the O-PCM. By comparing the results for different materials, we find that GeS and Sb2S3 are the most effective modulation candidates in the propagation of TM-polarized and TE-polarized light, respectively.