Hybrid modes in plasmonic cavity array for enhanced hot-electron photodetection.

The plasmonic characteristics of a periodic array of cavities in a silicon substrate are investigated for hot-electron photodetection. Resonances of cavity surface plasmons bound to air cavities and silicon cavities, and resonance of Bragg-surface plasmon polaritons are illustrated by the map of metal absorption. Hybrid modes formed with combination of these modes can strongly enhance absorption in metal and be exploited to optimize hot-electron photodetectors for single-band and dual-band detection at optical communication wavelengths.