Ultrashort field emission in metallic nanostructures and low-dimensional carbon materials

Abstract

This study investigates recent advances in photoelectron emission generated by irradiating ultrashort lasers on metallic nanostructures and low-dimensional carbon materials. Recently, primary focus has been on improving the efficiency of emitters, i.e. increasing the number of field-emitted electrons and their respective kinetic energies. An example of this is the modification of the conventional metal nanotip through adiabatic nanofocusing and various plasmonic metal structures, such as nanorods and bowtie antenna. The coherent emission control with two color irradiation enabled modulation in the emission yield. In addition, THz waves near the metallic nanostructure induced a highly accelerated, monochromatic energy. Alternative to metallic nanotips, carbon nanotubes are emerging as efficient photoelectron emitters, due to the large enhancement factor associated with their high aspect ratio and damage threshold. They particularly allowed the use of femtosecond light sources with a relatively short wavelength, resulting in the generation of photoelectrons with a narrow bandwidth. Additionally, electronic control over the singlewalled nanotubes band structure added a degree of freedom for controlling the electron emission yield. Finally, we review the strong-field tunneling emission in graphene edge, with the emission yield showing an anomalous increase of nonlinear order, corresponding to the deep strong tunneling regime.

Coherent ultrafast photoemission from a single quantized state of a one-dimensional emitter

“…By tuning the electronic structure through the thermal control of the carrier concentration, precise control of the electron emission through an individual energy level was realized. The resonant tunneling was evidenced by a laser-induced negative differential resistance (NDR) effect (31,32), which suggests that a photoemission occurs when the 1D excited state in the CNT body is aligned with an individual quantized energy level confined within the 0D quantum well (33)(34)(35)(36)(37)(38). The quantized energy level in 0D cap can be controlled by adjusting the static voltage.…”

Impact of DC bias on Weak Optical-Field-Driven Electron Emission in Nano-Vacuum-Gap Detectors

“…Previous studies have investigated the effect of superimposed electric fields from optical and low-frequency electrical sources in different regimes and length scales [11,12,14]. However, in this work, we investigate the effect of such a combination of optical and DC bias fields at the nanoscale in the weak-field (sub 10 V nm −1 ) ultrafast (sub 100 fs) regime, which has received increasing attention in recent years given the rapid development of nanometer-scale fabrication processes and compact ultrafast optical sources [1,[15][16][17].…”