Abstract-Plasmon-enhanced LT-GaAs/AlAs heterostructure photoconductive antennas for sub-bandgap terahertz generation

Afshin Jooshesh, Faezeh Fesharaki, Vahid Bahrami-Yekta, Mahsa Mahtab, Thomas Tiedje, Thomas E. Darcie, and Reuven Gordon

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-18-22140

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 4.5 THz bandwidth and 75 dB signal-to-noise ratio (SNR) under 50 mW of 1570 nm excitation, whereas the structure without the AlAs layer gives 3 THz bandwidth, 65 dB SNR for the same conditions.

© 2017 Optical Society of America

Abstract-Plasmonic Antireflection Coating for Photoconductive Terahertz Generation

Faezeh Fesharaki, Afshin Jooshesh, Vahid Bahrami-Yekta, Mahsa Mahtab, Tom Tiedje, Thomas E. Darcie, Reuven Gordon

http://pubs.acs.org/doi/abs/10.1021/acsphotonics.7b00410

Plasmon-enhanced photoconductive antennas allow for improved performance, particularly in below-band-gap absorption devices using low-temperature-grown GaAs. Here we design the plasmonic nanostructures to act as antireflection coatings as well, achieving below 10% reflection at 1570 nm wavelength in an optimized device. Quantitative agreement is seen between experiment and theory. Terahertz emission field amplitudes demonstrate 18 times enhancement compared to that of a conventional terahertz photoconductive antenna on the same substrate.

Abstract-Plasmonic Anti-reflection Coating for Photoconductive Terahertz Generation

Faezeh Fesharaki, Afshin Jooshesh, Vahid Bahrami-Yekta, Mahsa Mahtab, Tom Tiedje, Thomas E. Darcie, and Reuven Gordon

http://pubs.acs.org/doi/abs/10.1021/acsphotonics.7b00410?journalCode=apchd5

Plasmon-enhanced photoconductive antennas allow for improved performance, particularly in below-bandgap absorption devices using low-temperature grown GaAs. Here we design the plasmonic nanostructures to act as anti-reflection coatings as well, achieving below 10% reflection at 1570 nm wavelength in an optimized device. Quantitative agreement is seen between experiment and theory. Terahertz emission field amplitudes demonstrate eighteen times enhancement compared to that of a conventional terahertz photoconductive antenna on the same substrate.