Photonic integrated circulators based on iron garnets without external magnetization

Abstract

A new compact optical circulator based on a photonic crystal made of a triangular lattice of air holes etched in a magneto-optical material that does not require an external DC magnetic field to keep its saturated magnetic state is presented. The design has a threefold rotational symmetry and it consists of three single-mode waveguides and one resonator supporting dipole resonances introduced in the photonic crystal structure. Computational simulations of the circulator demonstrate that, at the 1.55 µm wavelength, the insertion losses are about -1 dB, while the isolation and reflection levels are about -15 dB and -24 dB, respectively.