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 mu m as the grid period varies from 3.6 to 4.5 mu m. The absorption peak wavelength obeys the equation sin theta/lambda + n/a = alpha/lambda with an experimentally determined value of 3.1 for alpha. The plasmon absorption is similar to 25% and incorporation of plasmon effects into FIR detectors could lead to enhanced response.