Terahertz emission characteristics of ErAs:InGaAs-based photoconductive antennas excited at 1.55 μm

We characterize ErAs:In(0.53)Ga(0.47)As superlattices as substrates for photoconductive terahertz emitters excited at 1.55 mu m. The bandwidth of the emitted radiation is studied as a function of the superlattice period (or equivalently the electron lifetime) and the applied bias field. The results show that a variation in the electron lifetime from 0.2 to 6.3 ps does not considerably influence the bandwidth of the emitted radiation. However, the bandwidth increases linearly from 2.6 to 3.0 THz as the applied bias field is increased from 7 to 30 kV/cm. At higher bias fields, saturation is observed. The largest measured bandwidth is 3.1 THz.