Suspended nanomembrane silicon photonic integrated circuits

Leveraging the low linear and nonlinear absorption loss of silicon at mid-infrared (mid-IR) wavelengths, silicon photonic integrated circuits (PICs) have attracted significant attention for mid-IR applications including optical sensing, spectroscopy, and nonlinear optics. However, mid-IR silicon PICs typically show moderate performance compared to state-of-the-art silicon photonic devices operating in the telecommunication band. Here, we proposed and demonstrated suspended nanomembrane silicon (SNS) PICs with light guiding within deep-subwavelength waveguide thickness for operation in the short wavelength mid-IR region. We demonstrated key building components, namely, grating couplers, waveguide arrays, micro-resonators, etc., exhibiting excellent performances in bandwidths, back reflections, quality factors, and fabrication tolerance. Moreover, we show that the proposed SNS PICs have high compatibility with the multi-project wafer foundry services. Our study provides an unprecedented platform for mid-IR integrated photonics and applications.