Plasmonic efficiency enhancement at the anode of strip line photoconductive terahertz emitters

Abstract

We investigate strip line photoconductive terahertz (THz) emitters in a regime where both the direct emission of accelerated carriers in the semiconductor and the antenna-mediated emission from the strip line play a significant role. In particular, asymmetric strip line structures are studied. The widths of the two electrodes have been varied from 2 µm to 50 µm. The THz emission efficiency is observed to increase linearly with the width of the anode, which acts here as a plasmonic antenna giving rise to enhanced THz emission. In contrast, the cathode width does not play any significant role on THz emission efficiency.

Photoconductive emitters for pulsed terahertz generation

“…This is due to higher average temperature at the PC gap, as smaller contacts fail to remove as much heat from active material reducing the carrier mobility of the sample. This effect has been confirmed through other studies [185,186].…”

Photoconductive Arrays for High-Field Terahertz Generation

“…1(a). As the THz field has been shown to be proportional the electrode width, this has been factored into the design [5]. Furthermore, the intentional use of curved electrode ends, compared with sharp rectangular points, is important in this structure as it prevents the concentration of localized electric field known to damage the device at high voltages.…”

Enhanced THz Emission from Photo-ConductiveAntennas by integrating photonic structures onSemi-insulating GaAs substrate

“…Recently, semi-insulating GaAs (SI-GaAs) with artificially irradiated controlled defect sites has been shown to have higher emission efficiencies 26,27 . Researchers have also addressed other aspects such as, adaptive design of electrodes [28][29][30] , plasmonic electrodes 31,32 , optical nanostructures for higher carrier concentrations and shorter carrier lifetimes [33][34][35][36][37] , micro-lens array coupled to PCAs for efficient collection of THz radiation 23,24,38 . The efficient generation of photo-excited carriers, and thereby enhanced THz emission, depends on the effective coupling of the exciting laser beam on to the PCA.…”