Arkabrata Bhattacharya, Dipa Ghindani, and S. S. Prabhu
 |
| Schematic showing the fabricated PCA on SI-GaAs substrate. Inset shows the embedded metasurface in the photoconductive gap of the PCA. The TiO2 antireflection coating has not been shown here. (b) SEM image of the fabricated devices. The First and the third devices have nanostructured PC gap, while the second and the fourth are bare PCAs for reference. |
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-21-30272
In this article, we demonstrate a technique to enhance the Terahertz (THz) emission bandwidth from photo-conductive antenna (PCA) based on semiconducting substrates by manipulating the surface carrier dynamics of the semiconductor. Bandwidths in PCAs are limited by the decay of the photogenerated charge carriers, which in case of SI-GaAs is in the orders of 50 picoseconds. We show, with an embedded design of plasmonic meta-surface in the photoconductive gap of a PCA, it is possible to enhance the emission bandwidths by more than 50 percent. This is due to the fact that these nano-structures act as local recombination sites for the photogenerated carriers, effectively reducing the carriers’ lifetime. Additionally, the defect sites reduce the terminal current, thereby reducing the Joule heating in the device. Furthermore, the meta-surface also facilitates higher in-coupling of the exciting infrared light on to the PCA, thereby increasing the optical-to-THz conversion efficiency of the device.
© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement
No comments:
Post a Comment