All-wet etched high-Q optical microcavity on a silicon chip

Optical microcavities with high quality factors can significantly enhance the intracavity power density and have become a superior platform for studying quantum electrodynamics, nonlinearities, and sensing. Minimized and compact on-chip devices require the integration of microcavities with versatile functions that can be implemented by techniques compatible with semiconductor industries. However, the silicon dry etch technique commonly used to shape silicon wafers limits the massive production of microcavities. Here, an all-wet etching technique is proposed to fabricate on-chip microcavities with the aid of photolithography. On-chip silica microdisks with quality factors of ∼105 are demonstrated, and optical modes with quality factors up to 106 are also observed. The proposed technique opens an avenue for economical, easy handling, and scalable production of on-chip microcavities using foundry-based technologies.