Angular-dependent photodetection enhancement by a metallic circular disk optical antenna

Abstract

In this paper, we analyze the plasmonic resonance excited by linearly polarized longwave infrared (LWIR) plane waves in a metallic circular disk optical antenna (MCDA). The surface current distributions are simulated at different wavelengths, incident angles, and polarizations. The excited surface plasmonic resonance waves (SPRs) are different from the Bessel-type of SPR modes and closely resemble those in a monopole antenna. An MCDA coupled LWIR quantum dot infrared photodetector (QDIP) was fabricated and measured at different LWIR plane wave wavelengths and incident angles. A linear correlation between the enhancement ratio and the integrated square of the current is obtained, indicating the monopole antenna effect is a dominating factor for the plasmonic enhancement.