All-Optical Hybrid VO2/Si Waveguide Absorption Switch at Telecommunication Wavelengths

Vanadium dioxide (VO2) is one of the most promising materials for developing hybrid photonic integrated circuits (PICs). At telecommunication wavelengths, VO2 exhibits a large change on the refractive index (Delta n similar to 1 and Delta kappa similar to 2.5) between its insulating and metallic state. Such insulating-to-metal transition (IMT) can be triggered by light, which could enable all-optical hybrid VO2-waveguide devices. Here, we experimentally demonstrate an all-optical absorption switch using a hybrid VO2/Si waveguide fully compatible with the silicon photonics platform. All-optical characterization was carried out for TE polarization and at telecommunication wavelengths using an in-plane approach. The temporal dynamics were retrieved by means of pump-probe measurements. Our results show an extinction ratio of 0.7 dB/mu m with a maximum switchable length of 15 mu m, a switching speed as low as 318 ns, and an energy per switch of 15.8 nJ. The inherit large optical bandwith of a non-resonant waveguide poses this device as a promising candidate for developing all-optical and broadband silicon PICs.