Chris Berry, a doctoral student in the Electrical Engineering program, received Best Student Paper Award (3rd place) at the 2013 International Microwave Symposium for his paper Nanoscale Contact Electrodes for Significant Radiation Power Enhancement in Photoconductive Terahertz Emitters.
This paper presents a novel photoconductive terahertz emitter that achieves a dramatic increase in performance over current emitters. The improved performance results from the use of a plasmonic contact electrode configuration which enhances the optical-to-terahertz conversion efficiency by up to two orders of magnitude. This technique addresses the most important limitations of conventional photoconductive terahertz emitters, namely low output power and poor power efficiency. These limitations originate from the inherent tradeoff between high quantum efficiency and ultrafast operation of conventional photoconductors.
The key novelty in this work is the use of a plasmonic contact electrode configuration that accumulates a large number of photo-generated carriers in close proximity to the contact electrodes. This allows the photo-generated carriers to drift to the terahertz radiating antenna within a sub-picosecond timescale. In other words, the tradeoff between photoconductor ultrafast operation and high quantum efficiency is mitigated by spatial manipulation of the photo-generated carriers.
The paper was co-authored by Mohammed R. Hashemi, Mehmet Unlu, and his advisor, Prof. Mona Jarrahi.
Read more about this research and its applications in imaging (including medical imaging) and chemical detection.