Unusually strong, tunable, and nonreciprocal light trapping and absorption in helically structured magnetoactive media

Abstract

We investigated the absorption properties of photonic structures with both large optical activity and magneto-optical activity parameters. The photonic structure is a periodic helical 1D medium in an external magnetic field. The magneto-optical activity parameter g change effects on the absorption nonreciprocity spectra for both linear and circular polarizations and those for unpolarized (natural) light were investigated. We showed that in certain cases, the external magnetic field leads to a strong increase in light trapping, absorption, and absorption nonreciprocity. This system can operate as a powerful light source and asymmetric and tunable wide range high absorber as well. We also investigated the dependence of Q (total energy absorbed in a finite spectral range) and its density on the layer thickness for different values of magneto-optical activity parameter g. With a change in the parameter g, the value of Q changes over a wide range (increasing or decreasing over 40 or more times), i.e., we have a broadly tunable and nonreciprocal integral absorption, again, for both polarized and unpolarized light. We showed that there are values of the parameter of magneto-optical activity at which the integral absorption does not depend on the polarization of the incident light.