V-Groove Channel Waveguides and Mach–Zehnder Interferometer in Hyperbolic van der Waals MoOCl₂

Miniaturization of photonic integrated circuits is a long-standing problem in optical engineering. Nowadays, the most promising material platform for integrated photonics are anisotropic van der Waals materials due to overcoming the light diffraction limit. Here, we numerically study v-groove channel waveguides formed in a 50-nm-thick slab of the in-plane hyperbolic in visible and near-infrared ranges van der Waals material MoOCl₂. At the telecom wavelength 1550 nm, a channel supports a guided mode with an effective index 1.0206 and a decay length of 13.7 µm. We also design a Mach–Zehnder–type interferometric layout with a maximum splitter angle of approximately 7° for demonstration of a possible practical application in a telecom range and in-plane angular channel modes propagation characteristics. We demonstrate that using MoOCl2 instead of gold leads to a tenfold reduction in the linear dimensions of the photonic integrated circuit. Therefore, we envision that by combining the extraordinary material properties of MoOCl2 with the v-shaped geometry of waveguides, one can make the integration density of photonic devices close to electronics.