NONRECIPROCAL LIGHT CHANNELING IN A FILM BY A MAGNETIC NONUNIFORMITY AKIN TO A NEEL DOMAIN-WALL

The problem of light propagation along a magneto-optic nonuniformity w hich is similar to a wide Neel domain wall is analyzed by perturbation theory. The Maxwell equations of the three-dimensional problem are re duced to a system which describes the amplitude evolution of the coupl ed TM and TE modes in a two-dimensional approximation. Numerical analy sis shows a strong nonreciprocal character of light beam propagation: The waveguide supports a localized TRI-like mode in one direction and scatters the light beam in the opposite direction. For a garnet film o f 1 mu m thickness, having a Faraday rotation of 3150 degrees/cm at a wavelength of 1.3 mu m, an isolation of 25 dB is calculated for a prop agation length of 1 cm. This waveguide may be used as optical isolator . It may also be applied as a magneto-optical switch or modulator tune d by an external magnetic field. (C) 1998 American Institute of Physic s.