Temporal dynamics of all-optical switching in hybrid VO2/Si waveguides

TL;DR

This study investigates the all-optical switching dynamics of VO2 in hybrid VO2/Si waveguides, revealing thermal-driven switching times in the micro- to nanosecond range and potential for faster, energy-efficient photonic devices.

Contribution

It provides the first experimental analysis of VO2's temporal response in waveguides, highlighting thermal mechanisms and engineering prospects for nanosecond switching.

Findings

Switching times in the micro- to nanosecond range.

Thermal absorption triggers phase transition.

Potential for nanosecond switching with nanojoule energy.

Abstract

Vanadium dioxide (VO2) is one of the most promising materials for developing hybrid photonic integrated devices (PICs). However, despite switching times as low as a few femtoseconds have been reported, the all-optical temporal dynamics of VO2 embedded in a waveguide using an in-plane optical signal remain still hidden. Here, we experimentally investigate this behavior in hybrid VO2/Si waveguides by using pump-probe measurements at telecom wavelengths. Our results show switching times in the micro and nanosecond range, suggesting that the phase transition is triggered thermally from the light absorbed by the VO2 and the temporal response is governed by thermal conductive dynamics. By properly engineering the optical pulse, we prospect switching times of nanoseconds with an energy consumption of a few nanojoules. Our results unveil a new temporal dynamic that would be useful for developing future all-optical VO2 photonic integrated devices.