Reconfigurable Structured Light-Driven Terahertz Emission and Modulation in Interdigitated Photoconductive Antennas

The interdigital photoconductive antennas (iPCA) can be used for terahertz (THz) wave generation with high energy utilization and terahertz emission efficiency. However, adjacent electrode gaps of iPCA with inversed bias fields emit terahertz pulses with opposite polarity, resulting in the destructive interference of THz waves in the far-field. To improve the terahertz generated by iPCA, we propose a method to efficiently pump the emission arrays with reconfigurable structured light generated using liquid crystal spatial light modulator (LC-SLM). After being corrected by adaptive optics, the pump light is modulated into specific shapes that align with the electrode gaps of the antenna, each subjected to a unidirectional bias field. This tailored modulation optimally utilizes the pump power, mitigating the occurrence of THz pulses with opposing polarities, which lead to undesirable destructive interference in the far-field. Our proposed design yields impressive coherent combining efficiencies for the THz electric field. The overall terahertz output demonstrates a proportional augmentation corresponding to the escalating number of elements within the array. Notably, programmable structured light patterns can be generated by varied methods and contribute to the modulation of output THz. For example, the system allows for real-time phase reversal of THz emission by adjusting the location of the pump light. This capability opens up new possibilities for applications in the precise control of phase and amplitude of the THz field. Overall, we demonstrate an innovative strategy for optimizing THz generation in IPCA, showcasing its potential to inspire advancements in the manipulation of THz fields and the improvement of THz output. It has great potential applications in terahertz biophysics.