Showing posts with label Levi Smith. Show all posts
Showing posts with label Levi Smith. Show all posts

Thursday, May 27, 2021

Abstract-Tapered transmission lines for terahertz systems

 

Levi Smith, Walid Gomma, Hadi Esmaeilsabzali, and Thomas Darcie

Microscope image of fabricated device

https://www.osapublishing.org/oe/fulltext.cfm?uri=oe-29-11-17295&id=451243

Complex terahertz (THz) System-on-Chip (TSoC) circuits require ultra-wideband low-loss low-dispersion interconnections between building-block components of various dimensions and characteristics. Tapered transmission lines, which enable the gradual transformation of both physical dimensions and characteristic impedance, are a convenient basis for these interconnections. In this paper, we quantify both experimentally and through simulation, the efficacy of transmission-line tapers connecting two different coplanar-strip transmission-line configurations, for frequencies up to 2.0 THz and with 25 GHz spectral resolution. We demonstrate tapers that enable transitioning from a small device-constrained transmission-line dimension (10 μm line width) to a lower-loss (20-40 μm line width) dimension, as a method to reduce the overall attenuation, and outline design constraints for tapered sections that have minimal detrimental impact on THz pulse propagation.

© 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Wednesday, November 5, 2014

Abstract-Nanoplasmonics enhanced terahertz sources



Afshin Jooshesh, Levi Smith, Mostafa Masnadi-Shirazi, Vahid Bahrami-Yekta, Thomas Tiedje, Thomas E. Darcie, and Reuven Gordon  »View Author Affiliations
http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-22-23-27992
Optics Express, Vol. 22, Issue 23, pp. 27992-28001 (2014)
http://dx.doi.org/10.1364/OE.22.027992

Arrayed hexagonal metal nanostructures are used to maximize the local current density while providing effective thermal management at the nanoscale, thereby allowing for increased emission from photoconductive terahertz (THz) sources. The THz emission field amplitude was increased by 60% above that of a commercial THz photoconductive antenna, even though the hexagonal nanostructured device had 75% of the bias voltage. The arrayed hexagonal outperforms our previously investigated strip array nanoplasmonic structure by providing stronger localization of the current density near the metal surface with an operating bandwidth of 2.6 THz. This approach is promising to achieve efficient THz sources.
© 2014 Optical Society of America