High Visibility in Two-Color Above-Threshold Photoemission from Tungsten Nanotips in a Coherent Control Scheme

TL;DR

This study demonstrates near-perfect control of above-threshold photoemission from tungsten nanotips using a coherent control scheme with femtosecond laser pulses, achieving 97.5% modulation by manipulating pulse delay and intensity.

Contribution

It introduces a method for coherent control of photoemission from nanotips with unprecedented modulation depth, supported by quantum pathway interference and LDOS simulations.

Findings

Achieved 97.5% modulation of electron emission.

Controlled emission by adjusting pulse delay and intensity.

Supported experimental results with quantum pathway interference models.

Abstract

In this article we present coherent control of above-threshold photoemission from a tungsten nanotip achieving nearly perfect modulation. Depending on the pulse delay between fundamental (1560 nm) and second harmonic (780 nm) pulses of a femtosecond fiber laser at the nanotip, electron emission is significantly enhanced or depressed during temporal overlap. Electron emission is studied as a function of pulse delay, optical near-field intensities, DC bias field, and final photoelectron energy. Under optimized conditions modulation amplitudes of the electron emission of 97.5% are achieved. Experimental observations are discussed in the framework of quantum- pathway interference supported by local density of states (LDOS) simulations.