High-Q chalcogenide racetrack resonators based on the multimode waveguide

Abstract

We propose and demonstrate a high quality (Q) factor racetrack resonator based on uniform multimode waveguides in high-index contrast chalcogenide glass film. Our design features two carefully designed multimode waveguide bends based on modified Euler curves, which enable a compact 180° bend and reduce the chip footprint. A multimode straight waveguide directional coupler is utilized to couple the fundamental mode without exciting higher-order modes in the racetrack. The fabricated micro-racetrack resonator shows a record-high intrinsic Q of 1.31×106 for selenide-based devices, with a relatively low waveguide propagation loss of only 0.38 dB/cm. Our proposed design has potential applications in power-efficient nonlinear photonics.