We demonstrate a hybrid silicon-vanadium dioxide (Si-VO 2 ) electro-optic modulator that enables direct probing of both the electrically triggered semiconductor-to-metal phase transition in VO 2 and the reverse transition from metal to semiconductor. By using a twoterminal in-plane VO 2 electrical switch atop a single-mode silicon waveguide, the phase change can be initiated electrically and probed optically, separating the excitation and measurement processes and simplifying the analysis of the metal-to-semiconductor dynamics. We demonstrate a record switch-on time for high-speed electrical semiconductor-to-metal transition, with switching times less than 2ns, and quantify the slower inverse transition, which is dominated by thermal dissipation and relaxation of the metallic rutile lattice to the monoclinic semiconducting

We present a computational design for an integrated electro-optic modulator based on near-field plasmonic coupling between gold nanodisks and a thin film of vanadium dioxide on a silicon substrate. Active modulation is achieved by applying a time-varying electric field to initiate large changes in the refractive index of vanadium dioxide. Significant decrease in device footprint (200 nm x 560 nm) and increase in extinction ratio per unit length (9 dB/µm) compared to state-of-the-art photonic and plasmonic modulators are predicted.

An integrated silicon photonics coupler for fiber to waveguide conversion was designed employing a transformation optics approach. Quasi-conformal mapping was used to obtain achievable material properties, which were realized by a distorted hexagonal lattice of air holes in silicon. The coupler, measuring only 10 μm in length and fabricated with a single-step lithography process, exhibits a peak simulated transmission efficiency of nearly 100% for in-plane mode conversion and a factor of 5 improvement over butt coupling for fiber to waveguide mode conversion in experimental testing.

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