Ultrahigh-Q on-chip silicon-germanium microresonators for quantum transduction

Abstract

As an entirely monocrystalline photonics platform, $Si_1-xGe_x/Si$ is a promising has exceptionally low losses in both microwave [1] optical [2] and domains, with internal optical quality factors reaching 170M at room temperature. At 4 K, $Si_1-xGe_x/Si$ waveguides still have high quality factors but also a low threshold for bistability and pulsation, which are nonlinear optical effects deriving from the interplay between optically generated free carrier dispersion and thermo-optics. While instabilities deriving from them can be detrimental, they can be mitigated by applying DC electric fields. Together with silicon’s intrinsically high (3) tensor, this active control over nonlinearities could lead silicon germanium to applications like electro-optic modulation [3], optical logic, Kerr comb generation, and quantum transduction [4]. This work was funded by Laboratory of Physical Sciences CQTS program through an Army Research Office grant W911NF-18-1-0022. [1] Schilling et al, Optica 9, 284 (2022) [2] Sandberg et al, Appl. Phys. Lett. 118, 124001 (2021) [3] Timurdogan et al., Nature Photonics 11, 200 (2017). [4] Orcutt et al, Quant. Sci. Tech. 5, 034006 (2020)