Thermal detection of surface plasmons on gold nanohole arrays

We used a thin-film thermocouple to detect the thermal effect of surface plasmons excited in Au nanohole array structures. We found that the thermal electromotive force of Au film with periodic nanohole structures is three times greater than that of a bare Au film for 785-nm laser excitation at a given power. This effect is caused by the resonant excitation of localized surface plasmons in the nanoholes. In addition, we found that the thermal electromotive force (EMF) of the Au film with dumbbell-like nanohole arrays depends strongly on the incident polarization. The thermal EMF is the greatest when the excitation light is polarized perpendicular to the long axis of the dumbbell.