Efficient 3-dimensional photonic-plasmonic photo-conductive switches

Abstract

The efficiency of Terahertz photo-conductive switches was overlooked for a very long time. These optoelectronic devices have been dominating so far the fields of optics and ultrafast spectroscopy, however nowadays they are making their way through to new and emerging fields of research where power efficiency is of great importance. To address the efficiency problems, in this contribution, we present a new photo-conductive switch whose design is 3-dimensional. In contrast to conventional planar designs, the proposed photo-conductive switch can enhance the overall efficiency by increasing the optical absorption within the device, while at the same time maximizing the carrier collection at the electrodes. The design of this novel photoconductive switch takes advantage of photonic and plasmonic modes that are excited in the device due to a periodic array of nanopillars, whereas the collection efficiency is optimized by converting each nanopillar into a single nano-photo-conductive switch. By numerically simulating this novel device, we show a 50-fold increase in the overall generated current and a 5-fold bandwidth increase compared to traditional interdigitated planar photo-conductive switches. The first prototypes of this novel device are fabricated and preliminary measurements are ongoing. This opens up a wealth of new possibilities in research fields where efficient low power devices are indispensable.