Figure 5

(a) Photocurrents in the nanocavity-based terahertz source and the terahertz source fabricated on the LT-GaAs substrate as a function of the bias voltage under an optical pump power of 720 mW. (b) Photocurrents in the nanocavity-based terahertz source and the terahertz source fabricated on the LT-GaAs substrate as a function of the optical pump power under a bias voltage of 18 V.