Strong Nonreciprocal Radiation in a InAs Film by Critical Coupling with a Dielectric Grating
Xiaohu Wu, Zhaoxian Chen, Feng Wu
Abstract
Magneto-optical materials, which can violate the traditional Kirchhoff's law, provide new opportunities in energy harvesting and infrared camouflage. However, bulk magneto-optical materials usually possess weak nonreciprocity in the infrared band, which heavily impedes their applications in thermal radiation. Therefore, it is urgent to propose new methods to realize strong nonreciprocity in an infrared bands with an external magnetic fields as small as possible. Herein, we propose to enhance the nonreciprocal radiation in an InAs film by critical coupling with a dielectric grating. The numerical results show that strong nonreciprocal radiation can be obtained at wavelength 15.835 m when the external magnetic field is 2 Tesla. The enhanced nonreciprocity is attributed to the critical coupling between the intrinsic loss in the InAs film and the external leakage in the dielectric grating. Both coupled mode theory and distribution of magnetic field are used to confirm the underlying mechanism. We believe that the method proposed in this work is of practical interest.