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This paper presents a 3D model of a photoconductive antenna (PCA) on semiconductor substrate. The simulations were conducted using the COMSOL Multiphysics package. The model considers the laser excitation and the carrier generation acceleration in the semiconductor layer. The computational work was achieved using the frequency-domain RF module and the semiconductor module. The results demonstrate that simulating the active area alone produces sufficient accuracy ~ 0.01% in the RF module solution (solution of the electric and magnetic fields) and ~ 0.23% in the semiconductor solution (photocurrent solution). The reduction in the simulated area helps minimizing the required CPU time and memory requirement in the 3D model at THz frequencies. The largest case in this study was simulated at the National XSEDE Supercomputing with ~ 0.3 billion unknowns and memory requirement of ~ 3.2TB in the RF module.
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null (Ed.)This paper presents an investigation of terahertz (THz) signals generated using photoconductive antennas (PCAs) based on different electrode geometries. The geometry of the electrodes influences the shape of the THz pulse and its frequency spectrum. The geometry can be used to provide improvements to the bandwidth of the PCA. We used the transient solution of the RF module of COMSOL Multiphysics to simulate the radiated electric field based on using the photoconductive current as a time domain source in the gap of the antenna. The dimensions of a previously published bowtie H-dipole antenna were used as reference that was modified to three new configurations. The results show that the bowtie-H-dipole antenna provided broader bandwidth compared with the fractal, slot, and/or circular shape electrodes PCAs.more » « less
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This paper presents an investigation of terahertz (THz) signals generated using photoconductive antennas (PCAs) based on different electrode geometries. The geometry of the electrodes influences the shape of the THz pulse and its frequency spectrum. The geometry can be used to provide improvements to the bandwidth of the PCA. We used the transient solution of the RF module of COMSOL Multiphysics to simulate the radiated electric field based on using the photoconductive current as a time domain source in the gap of the antenna. The dimensions of a previously published bowtie H-dipole antenna were used as reference that was modified to three new configurations. The results show that the bowtie-H-dipole antenna provided broader bandwidth compared with the fractal, slot, and/or circular shape electrodes PCAs.more » « less
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This paper presents the signal generation measurements of LT-GaAs photoconductive antenna (PCA) emitters. These measurements were developed in an open-bench time-domain spectroscopy (TDS) system. The main challenges presented here are associated with the alignment of the PCA devices and the location of the terahertz (THz) pulse with respect to the optical delay in the system. The position of the slow delay line was crucial for the location of the THz pulse, which helped in the correct alignment process of the emitter and detector devices.more » « less
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