SiN/VO2/SiN sandwich-based resonant waveguide grating to produce thermally activated optical components
Résumé
The insulator-to-metal transition (IMT) of vanadium dioxide (VO2) at around 68 ºC enables a variety of optical applications, including switching and modulation, and tuning of optical resonators. We designed and demonstrated 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 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 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. Our 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.