SiN/VO₂/SiN Sandwich‐Based Resonant Waveguide Grating to Produce Thermally Activated Optical Components

Abstract

The insulator‐to‐metal transition (IMT) of vanadium dioxide (VO2) at ≈68 °C enables a variety of optical applications, including switching and modulation, and tuning of optical resonators. This work designs and demonstrates a novel thermally activated optical switch consisting of a SiN/VO2/SiN multilayer sandwich structure with an AMONIL‐based grating with a reduced transition temperature of 47 °C. The optical switching in the multilayer is due to the IMT of the VO2‐embedded layer. Here, the asymmetrical TE1 mode exhibiting a quasi‐zero electric field in the center of the multilayer waveguide is excited in the resonant waveguide grating (RWG) structure under normal incidence via the AMONIL‐based grating printed on top, leading to high resonant transmittance (75%) at room temperature. Increasing the temperature to more than 47 °C causes VO2 to undergo an insulator‐to‐metal transition accompanied by optical modifications in the IR region, completely canceling the resonance effect, while reducing the transmittance to 30%. Further, the modeling results aimed at optimizing the design of the experimental structure. These results demonstrate good performance of the proposed design and pave the way to fabricate VO2‐based optical switches for photonics applications including lasers, sensors, and detectors, in which external stimuli such as heat affect the transmittance or reflectance spectrum.