Abstract
A terahertz photoconductive antenna placed on the back side of a semiconductor slab with and without a compact cylindrical semiconductor microlens on the front side is studied theoretically. The antenna is operated as a photomixer giving narrowband radiation at 1 THz. Radiation patterns and emitted powers are found to oscillate with slab thickness as a consequence of multiple-reflection interference. It is further shown that an antireflection layer on the lens may eliminate these oscillations to a large extent. In the absence of a lens, most of the radiation is trapped inside the semiconductor slab, and the radiation pattern is far from that of a pencil-beam. Both light trapping and radiation patterns are shown to be significantly improved by a very compact lens with a size smaller than a cubic wavelength. The improvements on outcoupling of radiation in a predominantly forward direction versus lens radius and height are mapped out. The calculated outcoupling efficiency of the antenna-lens system takes into account the Purcell effect and radiation trapped in the semiconductor slab. The antenna-lens system is modeled rigorously by using the Green’s function volume integral equation method in a form that exploits cylindrical symmetry.
Originalsprog | Engelsk |
---|---|
Tidsskrift | Journal of the Optical Society of America - B - Optical Physics |
Vol/bind | 37 |
Udgave nummer | 4 |
Sider (fra-til) | 1109-1115 |
Antal sider | 7 |
ISSN | 0740-3224 |
DOI | |
Status | Udgivet - 1 apr. 2020 |
Bibliografisk note
https://doi.org/10.1364/JOSAB.379115Emneord
- Optik
- Terahertz