Observation of optical isolation based on nonreciprocal phase shift in a Mach–Zehnder interferometer

Measurements up to 45° nonreciprocal phase shift using the transverse magneto-optical effect have been made in a hybrid Mach–Zehnder waveguide/fiber interferometer. BiLu-IG waveguides of various thicknesses and lengths have been used to study the length and thickness dependence of the effect at λ=1.55 μm. This interferometric scheme is also employed to observe optical isolation; an extinction ratio of 11 dB is obtained for the 45° nonreciprocal phase shift, in agreement with theoretical predictions.