Fano interference between resonant and leaky waves in 1D silicon photonic crystal microcavities

Abstract

Resonant integrated optical structures with spectra exhibiting asymmetric Fano line shapes are of interest for a variety of devices, including integrated sensors, electro-optic modulators and all-optical switches. Here we observe such line shapes in the transmission spectra of waveguide-loaded 1D photonic crystal (PC) microresonators, resulting from interference between the resonant transmission of the bus WG's fundamental quasi-TE mode, and leaky nonresonant transmission of a second-order quasi-TE mode through the PC region. The continuum state transmitted through the PC microcavity itself uniquely allows for devices requiring no additional waveguides or reflecting elements. Additionally, the devices are fabricated with 193-nm immersion photolithography in a CMOS memory process at Micron Technology, and though PC structures have previously been fabricated photolithographically, these are the first high-Q PC microcavity devices fabricated subject to the constraints and dielectric environment of a full electronics-capable CMOS process.