Publications by authors named "Afshin Jooshesh"
Article Synopsis
- THz-bandwidth pulses are created and transmitted through a specialized gold-plated waveguide, achieving high bandwidth and dynamic range.
- The system uses edge-pumped slotline detectors made of LT-GaAs positioned near the waveguide openings for effective detection.
- The goal is to establish a straightforward and efficient dispersion-free THz system suitable for research in free-space waveguides.
Photocurrent generation in low-temperature-grown GaAs (LT-GaAs) has been significantly improved by growing a thin AlAs isolation layer between the LT-GaAs layer and semi-insulating (SI)-GaAs substrate. The AlAs layer allows greater arsenic incorporation into the LT-GaAs layer, prevents current diffusion into the GaAs substrate, and provides optical back-reflection that enhances below bandgap terahertz generation. Our plasmon-enhanced LT-GaAs/AlAs photoconductive antennas provide 4.
View Article and Find Full Text PDFA near-field edge-coupled photoconductive free-space linear tapered slot antenna has been constructed as a planar alternative to the standard photoconductive switch coupled to a silicon substrate lens. The temporal response along the optical axis is investigated to ensure the structure itself does not introduce pulse distortion which would fundamentally limit the usefulness of the structure. Experimental results show that a 1.
View Article and Find Full Text PDFArticle Synopsis
- Researchers are utilizing plasmon enhancement in terahertz (THz) photoconductive switches that leverage low-temperature grown GaAs and femtosecond lasers.
- These plasmon-enhanced devices outperform existing InGaAs-based commercial products in bandwidth and power.
- This advancement could lead to affordable, high-performance portable systems for various applications, including spectroscopy, security, medical imaging, and communication.
Article Synopsis
- Scientists created hexagonal metal nanostructures to enhance local current density and manage heat at the nanoscale, boosting THz emission from photoconductive sources.
- The new device achieved a 60% increase in THz emission field amplitude compared to a commercial antenna, while using only 75% of the bias voltage.
- This hexagonal design outperforms earlier nanoplasmonic structures by better concentrating current density near the metal surface, with an operating bandwidth of 2.6 THz, indicating its potential for more efficient THz sources.