Silicon slotted photonic crystal cavities fabricated by deep-ultraviolet lithography

Abstract

Slotted photonic crystal (SPC) cavities provide strong evanescent fields, high quality factors, and small mode volumes. Hence, SPC cavities have been identified as promising candidates for the implementation of high-performance sensors and the development of hybrid devices combining silicon with other active materials. Nevertheless, most state-of-the-art demonstrations rely on electron beam lithography and operate in the telecommunications band near the 1550 nm wavelength. Here, we report the experimental demonstration of SPC cavities operating in the datacom O-band, near 1340 nm wavelength, fabricated using deep-ultraviolet (DUV) lithography. The O-band provides very interesting properties for sensing, communications, and hybrid integration: namely, lower optical absorption of water, lower dispersion in standard optical fibers, and the emission of active materials like carbon nanotubes. On the other hand, DUV fabrication opens interesting opportunities for large volume production. The proposed cavities exhibit a high quality factor exceeding 20,000 and a small mode volume of 0.023 ( λ / n ) 3 . These results open interesting perspectives to exploit enhanced light–matter interaction in SPC cavities harnessing industrial-like fabrication processes.