Plasmon Enhancements for FIR Detection

The use of plasmons to improve the response of FIR and THz detectors is generating extensive interest. Increased absorption due to the plasmonic absorption in a GaAs wafer with a thin oxide layer and a metal grid is reported. As expected, an absorption peak for E perpendicular to the grid is observed with peak wavelength varying from 12.6 to 14.3 mum as the grid period varies from 3.6 to 4.5 mum. The absorption peak wavelength obeys the equation sin thetas/lambda + n/a = alpha/lambda with an experimentally determined value of 3.1 for alpha. The plasmon absorption is -25% and incorporation of plasmon effects into FIR detectors could lead to enhanced response.