Proposal of a novel semiconductor optical waveguide isolator

A novel semiconductor optical waveguide isolator is proposed and analyzed. The proposed isolator has semiconductor optical amplifier (SOA) structure with a ferromagnetic metal (iron or nickel, for example) deposited on top for providing the magneto-optical effect as well as electrical contact. By nonreciprocal complex effective refractive index change through the magneto-optical effect and by appropriate current injection into SOA, only the backward-propagating light is to become subject to optical loss. The amount of nonreciprocal complex effective refractive index change has been estimated by a perturbation method. Wavelength dispersion and tolerance of fabrication errors have also been calculated. As a result the isolator is predicted to have practical isolation ratio (40 dB) with compact size (1.58 mm) at 1.55 μm wavelength, wide operation wavelength range, and large fabrication tolerance