Resonant silicon waveguide with strong transverse electric field rotation for magnetic-field-induced non-reciprocity.

Abstract

Non-reciprocal devices suitable for on-chip implementation are of high importance in modern photonics. In most cases, non-reciprocity is caused by the magneto-optical effect. At the same time, the external magnetic field is convenient to apply in the normal direction to the chip plane, which leads to Voigt geometry and modes with in-plane transverse rotations of the electric field. Here, we propose two resonant magnetic material-free silicon waveguides supporting such modes. The first one is a rectangular waveguide with air holes inside, whose modes have higher rotations at the telecom wavelength, but the silicon thickness is non-standard. The second one is based on a 220-nm-thick silicon waveguide compatible with commercially available silicon-on-insulator wafers. We also propose the scheme of an optical isolator based on a Mach-Zehnder interferometer with a rotation elements delay in its arms.