Plasmonic Nanodisk Thin-Film Terahertz Photoconductive Antenna

• Published in: IEEE transactions on terahertz science and technology 2018-03, Vol.8 (2), p.237-247
• Main Authors: Burford, Nathan M., Evans, Michael J., El-Shenawee, Magda O.
• Format: Article
• Language: English
• Subjects: Anodes; Nanostructures; Optical device fabrication; Optical imaging; Optical pumping; Photoconductive antenna (PCA); plasmonics; Plasmons; Principal component analysis; terahertz (THz)
• ISSN: 2156-342X; 2156-3446
• DOI: 10.1109/TTHZ.2017.2782484

This paper presents the design, fabrication, and measurement of a plasmonic thin-film terahertz photoconductive antenna. Conventional terahertz photoconductive antennas suffer from poor optical-to-terahertz conversion efficiency, often on the order of 10 −4 . This is due to the low quantum efficiency of the device. The goal of this work is to demonstrate enhanced terahertz emission from a plasmonic thin-film device architecture. The combination of plasmonic nanodisks, a 120-nm low-temperature-grown gallium arsenide thin-film, and a bottom-located bowtie antenna has demonstrated the feasibility of producing such devices. Fabrication attempts and failure analysis is discussed in this work. Experimental characterization measuring the peak-to-peak electric field values of the terahertz pulses emitted from the device prototypes showed approximately five times improvement in plasmonic thin-film devices compared to conventional devices. The plasmonic thin-film devices had a measureable terahertz bandwidth of ∼5 THz. This indicates that the plasmonic thin-film architecture has a potential for producing high optical-to-terahertz conversion efficiencies across a wide frequency range.