Faraday rotation in an InP waveguide

Waveguide Faraday rotation was demonstrated in an InP waveguide with magnetic dopants. The modal Verdet coefficient was 10°∕mmT at a wavelength of 1.55μm. It was found that the Verdet coefficient of the Fe:In1−xGaxAsyP1−y (x=0.290, y=0.628) core was 12.5°∕mmT at a wavelength of 1.55μm. The Verdet coefficient dependence on wavelength is in agreement with theory. The loss of the waveguide was 4.34dB∕cm, giving a magneto-optic figure of merit of 23 at a magnetic field of 1T and a wavelength of 1.55μm. This semiconductor waveguide shows promise for monolithically integrated optical isolators.