Cavity-enhanced mid-infrared absorption in perforated graphene

Graphene’s unique electronic structure due to its two-dimensional nature results in numerous advantageous properties, such as highly tunable chemical potential and the ability to support highly confined surface plasmons with exceptionally long lifetimes. In the context of optical absorbers, we theoretically calculate, using both analytical and numerical techniques, that the coupling of a continuous monolayer of perforated graphene to simple optical cavities results in greatly enhanced absorption in the mid-infrared regime due to graphene surface plasmons, with tunability of the resonance peak by more than its full width at half maximum. We identified and studied two distinct cases: quarter wavelength Fabry–Perot cavities which result in nearunity absorption, and deeply subwavelength cavities which enhance the universal graphene absorption approximately fourfold. The structural simplicity and large spectral tunability of the proposed designs render them applicable to infrared modulators, sensors, and bolometers. © 2014 Society of Photo-Optical Instrumentation Engineers (SPIE) [DOI: 10.1117/1.JNP.8.083888]