Optimize off-Voigt magnetic-field configurations for s-polarized nonreciprocal absorption

Determine whether an off-Voigt magnetic-field configuration can strengthen s-polarized nonreciprocal absorption in photonic-crystal-slab-on-InAs structures while balancing polarization conversion, chiral reflection, and the weaker overall nonreciprocal response associated with non-Voigt configurations.

Background

The demonstrated absorber operates in the Voigt configuration, where s-polarized nonreciprocity is relatively weak because the incident s-polarized electric field is parallel to the applied magnetic field. The discussion considers tilting the magnetic field away from the Voigt configuration as a possible way to give s-polarized light components perpendicular to the magnetic field and thereby produce a fundamentally nonreciprocal response.

However, such a configuration would introduce elliptical polarization inside InAs and polarization-conversion terms in the reflection matrix, complicating both analysis and design. It would also generally weaken the nonreciprocal optical response. The paper therefore identifies the net benefit of this trade-off as unresolved.