Plasmon-Enhanced below Bandgap Photoconductive Terahertz Generation and Detection

We use plasmon enhancement to achieve terahertz (THz) photoconductive switches that combine the benefits of low-temperature grown GaAs with mature 1.5 mu m femtosecond lasers operating below the bandgap. These below bandgap plasmon-enhanced photoconductive receivers and sources significantly outperform commercial devices based on InGaAs, both in terms of bandwidth and power, even though they operate well below saturation. This paves the way for high-performance low-cost portable systems to enable emerging THz applications in spectroscopy, security, medical imaging, and communication.