Giant optical resonances due to gain-assisted Bloch surface plasmons

摘要

We theoretically study Bloch surface plasmon (BSP) resonances in a thin subwavelength-structured metallic film adjacent to a submicron dielectric layer with gain. We show that for a planar gold-silver bimetallic grating resonant excitation of a BSP with the optimum value of gain may result in giant amplification of both transmitted and reflected waves. We explain the effect and illustrate how the electromagnetic near-field structure determines the type of interference (constructive or destructive) between the eigenmodes of the system, which results in either strong enhancement or suppression of the scattered waves.