An improved design of an integrated optical isolator based on non-reciprocal Mach-Zehnder interferometry

Non-reciprocal rib waveguide structures can be used to realize integrated o ptical isolators. In this paper, we propose a concrete design for a Mach-Ze hnder interferometer type isolator for TM modes. Just one of the arms, whic h are of equal length, is a nonreciprocal magneto-optic waveguide. The rest of the interferometer is reciprocal. Required fabrication tolerances are e stimated, and the entire isolator is simulated by applying a finite differe nce beam propagation method.