Compact and low loss magneto-optical waveguide isolator for TE mode based on lithium niobate on insulator

A novel optical isolator for fundamental transverse electric (TE) mode light based on asymmetric Mach–Zehnder interferometer (MZI) configuration is proposed. Asymmetric Mach–Zehnder interferometer (MZI) configuration is employed to generate nonreciprocal phase shift (NRPS). The optical isolator is implemented by applying Ce: YIG thin film on lithium niobate on insulator (LNOI). The NRPS of LN/Ce: YIG composite waveguides with different geometric sizes are calculated. The 30 dB isolation bandwidth is larger than 48.3 nm and the total simulated insertion loss is as low as 2.736 dB for NRPS waveguides with a length of 504.5μm at a wavelength around 1550 nm. Considering the state-of-art technology, the fabrication tolerances and a suitable process are discussed. Besides, a wavelength-tuning optical isolator is designed to cancel the phase deviation.