Improvement of Sub-Wavelength Grating Electrodes for Efficient Terahertz Photoconductive Antenna Based on Extraordinary Optical Transmission

Low efficiency of Terahertz (THz) radiation and radiation power have limited the development of THz Science and Technology. Thus, with the aims of achieving greater photoconductive current and improving radiation characteristics of THz photoconductive antenna (PCA), this study utilized Extraordinary Optical Transmission (EOT) of light passing through various subwavelength metal structures to control and restrain the light wave in subwavelength scale. Furthermore, by grooving the grating electrode structure, the influence of metal grating's EOT on the transmission field of PCA were investigated and analyzed. Simulation results show that the effect of local electric field enhancement is significant. When the incident power is 0.1W, the peak value of the local electric field reaches 7.04 x 10(7)V/m. In addition, comparing to the grating electrode with no groove structure in which the field intensity was less than 4.28 x 10(6)V/m, the local electric field increased by 16.4 times, respectively. Correspondingly, the photocurrent intensity of the improved photoconductive plasmonic structure is increased by 72.3 times. In conclusion, the improved plasma photoconductive structure was shown to obviously enhance the transmission field strength of semiconductor materials and the current of the PCA, and accordingly, to improve the THz radiation capability.