Abstract
Simulation of terahertz (THz) emission based on PC antennas imposes a challenge to couple the semiconductor carrier phenomena, optical transport and the THz energy transport. In this paper a Multi-physics simulation for coupling these phenomena using COMSOL Multi-physics 4.3b is introduced. The main parameters of THz photoconductive (PC) antenna as THz emitter have been reviewed and discussed. The results indicate the role of each parameter in the resulting photocurrent waveform and THz frequency: The radiated THz photocurrent waveform is determined by the photoconductive gap (the separation between the metallic electrodes), the incident laser illumination and the DC excitation voltage; while the THz frequency depends on the dipole length. The optimization of these parameters could enhance the emission. The simulations extend the advance of compact and cost-effective THz emitters.
Highlights
Simulation of THz generation based on PC antennas imposes a challenge to couple the semiconductor carrier phenomena, optical transport and the THz energy transport (Armstrong, 2012)
In-depth Monte-Carlo simulations describes in great detail the carrier dynamics in a photoconductive antenna (Castro-Camus, Lloyd-Hughes, & Johnston, 2005), without focus on effects related to antenna geometry
Results indicate that the radiated THz waveform is determined by the photoconductive gap, the incident laser illumination and the DC excitation voltage
Summary
Abhilash, Tewari, & Chaudhary, 2014), with the advantage that it can be patterned on the same semiconductor substrate used for THz detection. A PC antenna consists of two metal planar electrodes deposited on a semiconductor substrate. An optical beam illuminating the gap between the electrodes generates photo-carriers that are accelerated by static bias field to produce a time-varying current that radiates THz electromagnetic waves. Simulation of THz generation based on PC antennas imposes a challenge to couple the semiconductor carrier phenomena, optical transport and the THz energy transport (Armstrong, 2012). In-depth Monte-Carlo simulations describes in great detail the carrier dynamics in a photoconductive antenna (Castro-Camus, Lloyd-Hughes, & Johnston, 2005), without focus on effects related to antenna geometry. Results indicate that the radiated THz waveform is determined by the photoconductive gap (the separation between the metallic electrodes), the incident laser illumination and the DC excitation voltage. The simulation results are useful for designing THz antennas and tuning the excitation parameters for improved working of these devices
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