Interdigitated Photoconductive Antenna Pumped by Reconfigurable Structured Light for Terahertz Emission and Modulation

To improve the terahertz (THz) generation of the interdigitated photoconductive antenna (iPCA), we demonstrate, for the first time, a novel design to pump the emission arrays by reconfigurable structured light generated by a spatial light modulator. The pump light is modulated into shapes to match the antenna’s every other electrode gap which has unidirectional bias field. This design makes full used of the pump power and avoids THz pulses with opposite polarity which causes the unwanted destructive interference in the far-field. Coherent combining efficiencies of THz electric field of 92.23%, 74.94%, and 61.73% are achieved for two-, three-, and five-element pumping, respectively. In addition, real-time phase reversal of THz emission can be achieved by adjusting the pump light location. This system could inspire new and challenging applications in the phase and amplitude control of the THz field, and the enhancement of the THz signal output.