This paper presents a 3D model of a terahertz photoconductive antenna (PCA) using black phosphorus, an emerging 2D anisotropic material, as the semiconductor layer. This work aims at understanding the potential of black phosphorus (BP) to advance the signal generation and bandwidth of conventional terahertz (THz) PCAs. The COMSOL Multiphysics package, based on the finite element method, is utilized to model the 3D BP PCA emitter using four modules: the frequency domain RF module to solve Maxwell’s equations, the semiconductor module to calculate the photocurrent, the heat transfer in solids module to calculate the temperature variations, and the transient RF module to calculate the THz radiated electric field pulse. The proposed 3D model is computationally intensive where the PCA device includes thin layers of thicknesses ranging from nano- to microscale. The symmetry of the configuration was exploited by applying the perfect electric and magnetic boundary conditions to reduce the computational domain to only one quarter of the device in the RF module. The results showed that the temperature variation due to the conduction of current induced by the bias voltage increased by only 0.162 K. In addition, the electromagnetic power dissipation in the semiconductor due to the femtosecond laser source showed an increase in temperature by 0.441 K. The results show that the temperature variations caused the peak of the photocurrent to increase by
All-dielectric nanograting for increasing terahertz radiation power of photoconductive antennas
Photoconductive antenna (PCA) is a widely used terahertz (THz) radiation source, but its low radiated power limits the signal-to-noise ratio and bandwidth in THz imaging and spectroscopy applications. Here, we achieved significant PCA power enhancement through etching nanograting directly on the surface of the PCA substrate. The integrated nanograting not only maximizes the generation of photocarriers, but also benefits the bias electric field loaded on the photocarriers. Comparing with the conventional PCA, our PCA realizes a frequency independent THz power enhancement of 3.92 times in the range of 0.05-1.6 THz. Our results reported here not only provide a new method for increasing the THz power of PCAs, but also reveal another way that artificial nanostructures affect the PCAs, which paves the way for the subsequent researches of next-generation PCAs.
more » « less- NSF-PAR ID:
- 10161295
- Publisher / Repository:
- Optical Society of America
- Date Published:
- Journal Name:
- Optics Express
- Volume:
- 28
- Issue:
- 13
- ISSN:
- 1094-4087; OPEXFF
- Page Range / eLocation ID:
- Article No. 19144
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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and , respectively, under a maximum bias voltage of 1 V and average laser power of 1 mW. While simulating the active area of the antenna provided accurate results for the optical and semiconductor responses, simulating the thermal effect on the photocurrent requires a larger computational domain to avoid false rise in temperature. Finally, the simulated THz signal generation electric field pulse exhibits a trend in increasing the bandwidth of the proposed BP PCA compared with the measured pulse of a reference commercial LT-GaAs PCA. Enhancing signal generation and bandwidth will improve THz imaging and spectroscopy for biomedical and material characterization applications. -
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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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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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
