Phase-matched rectangular magnetooptic waveguides for applications in integrated optics isolators: numerical assessment

Phase matching between the fundamental TE and TM modes is an essential cond ition for complete polarization rotation in magnetooptic waveguides with lo ngitudinally directed magnetization. This condition can be satisfied with e mbedded square waveguides or with raised strip waveguides, provided that th e core dimensions are suitably chosen. Based on coupled mode theory for the vectorial modes of rectangular isotropic waveguides, we numerically simula te the performance of such devices in an experimental isolator setup, inclu ding birefringence and optical absorption. Fabrication tolerances with resp ect to all relevant parameters can be evaluated by simple perturbational ex pressions. Numerical verification shows that these formulas are accurate en ough for practical purposes. The tolerances qualify the traditional polariz ation rotator setup as competitive to recent proposals for integrated optic al isolators based on nonreciprocal interferometry. (C) 1998 Elsevier Scien ce B.V. All rights reserved.