Efficient Three-Dimensional Photonic–Plasmonic Photoconductive Switches for Picosecond THz Pulses

Abstract

The efficiency of photoconductive switches, which continue to be used for the generation and detection of THz waves, has been overlooked for a long time. The so far “optics-dominated” devices are making their way through to new and emerging fields of research that require ultrafast picosecond voltage pulses, as well as to new applications where power efficiency is of uttermost importance. To address the efficiency problems, in this Article we present a novel photoconductive switch that is based on a three-dimensional design. In contrast to conventional planar designs, our photoconductive switch drastically enhances the overall efficiency by maximizing the laser absorption within the device, while at the same time optimizing the carrier collection efficiency at the electrodes. To maximize the optical absorption, we take advantage of photonic and plasmonic modes that are excited in our device due to a periodic array of nanopillars, whereas the collection efficiency is optimized by converting each nanopillar into a single nano-photoconductive switch. Our numerical calculations show a 50-fold increase in the overall generated current and a 5-fold bandwidth increase compared to traditional interdigitated planar photoconductive switches. This opens up a wealth of new possibilities in quantum science and technology where efficient low power devices are indispensable.

Semiconductor-based electron flying qubits: review on recent progress accelerated by numerical modelling

“…On-chip optoelectronic conversion of a femtosecond laser pulse is so far the most promising technique to generate electrical pulses on the picosecond scale [116][117][118]. Combined with recent conversion efficiency improvements of these optoelectronic devices [119,120,169,170], such a real-time control is in reach and is currently pursued in the UltraFastNano project. Using these techniques, single-electron wave packets with a temporal width of 1 ps can be generated.…”

“…The generation of such pulses with cutting-edge microwave synthesis approaches is possible but at the technical limit. A promising alternative route allowing pulses with widths of 1 ps or smaller is the optoelectronic generation via ultrafast photo switches [116][117][118][119][120]. Besides a proper Leviton source, it is of utmost importance to design a quantum interferometer structure allowing for qubit manipulation with maximum efficiency.…”

Broadband Terahertz Emission from Photoconductive Devices

“…As a result, nearly the overall generated current and the bandwidth are increased by 50-fold and five times, respectively. However, such a device will request high-tech technology to fabricate it [34]. On the contrary, the metal-based nano-islands structures enhance the photoconductive THz emission with a less complicated fabrication process.…”

Self‐Induced Phase Locking of Terahertz Frequency Combs in a Phase‐Sensitive Hyperspectral Near‐Field Nanoscope

“…Alternative techniques have, therefore, been developed, including use of nonlinear crystals, [ 8 ] optical parametric oscillators, [ 9 ] and photoconductive switches. [ 10 ] However, the widespread use of THz FCs has been hampered by the size and complexity of the associated optical apparatus.…”