High Efficiency Interdigitated Terahertz Photoconductive Antenna Integrated With Cylindrical Lens Array

Cylindrical lens array (CLA) and plasmonic nano-grating structures were integrated with a large area interdigitated photoconductive antenna (PCA) for high-efficiency terahertz (THz) emitter applications. The peak-to-peak amplitude of THz radiation pulse from the CLA-integrated plasmonic PCA was enhanced 5.5 times compared with that from the conventional PCA without the plasmonic nano-grating and CLA. The highly localized electric field near the nanoscale grating shows enhanced optical absorption near the plasmonic nano-grating. The CLA focuses incident pulse laser light onto the interlaced active area to avoid destructive interference of the emitted THz waves. The enhanced optical absorption near the plasmonic nano-grating and the higher degree of laser light utilization increased the photo-generated carrier density at the device surface, leading to enhanced THz radiation power.