Non-reciprocal loss/gain of semiconductor amplifier covered by ferromagnetic layer

We show that an optical semiconductor amplifier covered by a ferromagnetic layer has a large difference in values of loss/gain for modes propagating in the opposite directions when the magnetization is directed perpendicularly to the light propagation direction and in the film plane. Thus, the amplifier covered by the ferromagnetic layer can itself act as an optical isolator. This design of the isolator can be beneficial for a monolithic integration of the optical isolator with semiconductor optoelectronic devices