A Computational Study on Performance Improvement of THz Signal from a Grating Photoconductive Antenna

A diffractive grating is a well-known optical component and is extensively used in many applications. This research work explores application of the diffractive grating in a photoconductive antenna (PCA) of a terahertz time domain spectroscopy (THz-TDS) system, by utilizing benefits of a sub-wavelength grating structure. The grating PCA structure was modeled and simulated by COMSOL Multiphysics software (COMSOL, Inc., Burlington, MA, USA). Performance of the proposed PCA design is studied in terms of its induced photocurrent. The effects of geometrical parameters of the grating are also investigated and analyzed through its optical and electrical responses. Thanks to the increase in absorption of the incident laser's electric field, the simulation results show a 63% increment of the induced photocurrent in the grating PCA, compared with the conventional planar PCA.