Polycrystalline-metal-ferromagnetic optical waveguide isolator (POWI) for monolithic-integration with diode-laser devices

Optical Faraday rotation in polycrystalline or amorphous thin films of ferromagnetic materials can be used to obtain true-optical isolators and nonreciprocal-TE-TM-mode converters which cover a wide wavelength range. These can be integrated with semiconductor lasers and other integrated optic devices because the films do not require epitaxial deposition. A detailed description and analysis of an integrable isolator with better than 30-dB isolation ratio and low insertion loss in the 1.5-μm wavelength region is given.