Optical modulator based on SiC structure using VO2 phase change material at 2.1 μm wavelength

This work proposes and investigates a PCM based optical modulator tailored for 2.1 μm wavelength operation, which finds diverse potential applications in medicine, wind speed sensing, water vapor detection, and carbon dioxide monitoring. We propose and simulate a SiC-core waveguide on SiO2 substrate employing VO2 as an integrated phase change cladding layer to achieve optical modulation. The optimized SiC core thickness is 400 nm based on modeling the SiO2/SiC/SiO2 waveguide structure. The waveguide structure can achieve optical switching by transitioning the phase of VO2 cladding between its metallic and insulating phases. Key optical parameters including the complex effective index, confinement factor, and normalized effective index are calculated as a function of VO2 thickness, ridge width, and wavelength for both TE and TM polarizations. The results indicate that for TM-polarized light, modulation of the optical signal can be achieved by electrically tuning the VO2 phase, yielding electro-absorption modulation over a 1 μm device length. Simulations demonstrate a propagation length of 2.1539 μm in the transparent insulating phase of VO2 and 0.1552 μm when transitioned to its opaque metallic phase, indicating strong optical absorption modulation suited for various applications. With customized engineering at a novel wavelength, this pioneering SiC-VO2 device holds great promise to further progress optical modulation capabilities for an array of applications across science and industry.