Efficient terahertz emission from InAs nanowires

TL;DR

This study demonstrates that InAs nanowire arrays emit intense terahertz pulses with significantly higher efficiency than planar substrates, due to coherent plasma motion and surface plasmon modes unique to high aspect ratio geometries.

Contribution

The paper reveals a new method for efficient terahertz emission using InAs nanowires, highlighting the role of surface plasmon modes and nanowire geometry in enhancing radiation.

Findings

THz emission efficiency is 15 times higher in nanowires than planar substrates.

Emission originates from low-energy acoustic surface plasmon modes.

Surface plasmon modes are specific to high aspect ratio nanowire geometries.

Abstract

We observe intense pulses of far-infrared electromagnetic radiation emitted from arrays of InAs nanowires. The THz radiation power efficiency of these structures is about 15 times higher compared to a planar InAs substrate. This is explained by the preferential orientation of coherent plasma motion to the wire surface, which overcomes radiation trapping by total-internal reflection. We present evidence that this radiation originates from a low-energy acoustic surface plasmon mode of the nanowire. This is supported by independent measurements of electronic transport on individual nanowires, ultrafast THz spectroscopy and theoretical analysis. Our combined experiments and analysis further indicate that these plasmon modes are specific to high aspect ratio geometries.