Photonics Research, 2018, 6 (9): 09000925, Published Online: Sep. 5, 2018
High-Q germanium optical nanocavity
Abstract
Mid-infrared (MIR) integrated photonics has attracted broad interest due to its promising applications in biochemical sensing, environmental monitoring, disease diagnosis, and optical communication. Among MIR integration platforms, germanium-based platforms hold many excellent properties, such as wide transparency windows, high refractive indices, and high nonlinear coefficients; however, the development of MIR germanium photonic devices is still in its infancy. Specifically, MIR high-Q germanium resonators with comparable performance to their silicon counterparts remain unprecedented. Here we experimentally demonstrate an MIR germanium nanocavity with a Q factor of ~ 18,000 , the highest-to-date of reported nanocavities across MIR germanium-based integration platforms. This is achieved through a combination of a feasible theoretical design, Smart-Cut methods for wafer development, and optimized device fabrication processes. Our nanocavity, with its high Q factor and ultrasmall mode volume, opens new avenues for on-chip applications in the MIR spectral range.
Ting-Hui Xiao, Ziqiang Zhao, Wen Zhou, Mitsuru Takenaka, Hon Ki Tsang, Zhenzhou Cheng, Keisuke Goda. High-Q germanium optical nanocavity[J]. Photonics Research, 2018, 6(9): 09000925.