Two-color Multiphoton Emission from Nanotips

TL;DR

This study demonstrates two-color multiphoton emission from tungsten nanotips, showing increased efficiency and controllability, with implications for ultrafast electron sources and nanophotonic devices.

Contribution

It introduces a new two-color multiphoton emission mechanism with quantum channel control, advancing understanding of photoemission processes from nanotips.

Findings

Two-color multiphoton emission achieved with increased quantum efficiency.

Quantum channel efficiency controlled by pulse delay.

Potential applications in ultrafast spin-polarized electron sources.

Abstract

Two-color multiphoton emission from polycrystalline tungsten nanotips has been demonstrated using two-color laser fields. The two-color photoemission is assisted by a three-photon multicolor quantum channel, which leads to a twofold increase in quantum efficiency. Weak-field control of two-color multiphoton emission was achieved by changing the efficiency of the quantum channel with pulse delay. The result of this study complements two-color tunneling photoemission in strong fields, and has potential applications for nanowire-based photonic devices. Moreover, the demonstrated two-color multiphoton emission may be important for realizing ultrafast spin-polarized electron sources via optically injected spin current.