Ultra-compact silicon photonic devices reconfigured by an optically induced semiconductor-to-metal transition

Vanadium dioxide (VO2) is a promising reconfigurable optical material and has long been a focus of condensed matter research owing to its distinctive semiconductor-to-metal phase transition (SMT), a feature that has stimulated recent development of thermally reconfigurable photonic, plasmonic, and metamaterial structures. Here, we integrate VO2 onto silicon photonic devices and demonstrate all-optical switching and reconfiguration of ultra-compact broadband Si-VO2 absorption modulators (L < 1 mu m) and ring-resonators (R similar to lambda(0)). Optically inducing the SMT in a small, similar to 0.275 mu m(2), active area of polycrystalline VO2 enables Si-VO2 structures to achieve record values of absorption modulation, similar to 4 dB mu m(-1), and intracavity phase modulation, similar to pi/5 rad mu m(-1). This in turn yields large, tunable changes to resonant wavelength, vertical bar Delta lambda(SMT)vertical bar similar to 3 nm, approximately 60 times larger than Si-only control devices, and enables reconfigurable filtering and optical modulation in excess of 7 dB from modest Q-factor (similar to 10(3)), high-bandwidth ring resonators (>100 GHz). All-optical integrated Si-VO2 devices thus constitute platforms for reconfigurable photonics, bringing new opportunities to realize dynamic on-chip networks and ultrafast optical shutters and modulators. (C) 2013 Optical Society of America