Wideband design of nonreciprocal phase shift magneto-optical isolators using phase adjustment in Mach-Zehnder interferometers

摘要

A wideband design is proposed for nonreciprocal phase shift magneto-optical isolators based on Mach-Zehnder interferometers. The wavelength dependence of nonreciprocal phase difference between the backward waves propagating in two interferometer arms is compensated for by that of reciprocal phase difference. This is realized by introducing an appropriate phase bias in one of interferometer arms. Two design examples are presented with a backward loss of >30 dB in the wavelength range of 1.40-1.63 (mu)m for a magnetic garnet waveguide isolator and of 1.485-1.630 (mu)m for a Si-wire waveguide isolator.