Hybrid silicon-vanadium dioxide electro-optic modulators

Abstract

Small-footprint, low-power devices that can modulate optical signals at THz speeds would transform next-generation onchip photonics. We describe a hybrid silicon-vanadium dioxide (Si-VO 2 ) electro-optic ring resonator modulator as a candidate platform for achieving this performance benchmark. Vanadium dioxide (VO 2 ) is a strongly correlated material exhibiting a semiconductor-to-metal transition (SMT) accompanied by large changes in electrical and optical properties. While VO 2 can be switched optically on a sub-picosecond time scale, the ultimate electrical switching speed remains to be determined. In a 5 µm radius Si-VO 2 ring resonator, we achieve 1.5 dB modulation in response to a 10 ns square voltage pulse of 2.5 V. In the steady state regime, we report a modulation depth of 10 dB. The larger modulation depth at longer timescales is attributed to a Joule heating contribution. Experimental results, corroborated by FDTD simulations, reveal the relationship between the portion of a VO 2 patch undergoing the SMT and the resulting effects on the Si-VO 2 device performance. This work indicates that with further reduction of VO 2 patch sizes and increase in resonator Q factor, there is promise for the Si-VO 2 ring resonator electro-optic modulator as a competitive option for on-chip photonics technology.

Silicon Waveguide Modulator with In-Line Phase Change Material

“…Hybrid Si photonic modulator geometries open the door to superior optical tunability while still maintaining integration compatibility with microelectronics technology by utilizing Si photonic structures as the information carrier. Promising materials for hybrid integration in Si photonic modulators include electro-optic polymers [4,5], plasmonic materials [6], twodimensional materials [7], germanium [8], and phase-change materials (PCMs) [9][10][11][12][13][14][15][16]. Of these materials, PCMs show the most versatile optical tunability (Δn > 1, Δκ ~ 10), therefore allowing for small modulator footprints without the use of a resonant structure.…”