Strong-Field Photoemission from Nanoscale Electron Sources

Strong-field photoemission from nanoscale electron sources harnesses intense optical fields to liberate electrons from metallic or molecular structures on sub-cycle timescales. Localised optical near-fields, amplified at nanometre tips or resonant junctions, lower the potential barrier and enable a transition from multiphoton absorption to tunnelling and over-the-barrier emission. This approach yields ultrashort electron pulses with attosecond resolution and high spatial coherence, facilitating real-time probing of quantum dynamics, ultrafast microscopy, photoelectron spectroscopy and on-chip lightwave electronics. Nanoscale emitters such as metallic nanotips, plasmonic nanostars and engineered molecular junctions provide tailored field enhancement and directional control through geometric design and phase-resolved driving pulses. Key challenges include the understanding of many-electron interactions, mitigation of space-charge effects in dense pulse regimes and precise synchronisation of carrier-envelope phase. Recent advances reveal new emission pathways with subnanometre modulation, coherent current steering and integration into chip-scale circuits under ambient conditions. The synergy of theory and experiment is driving the global expansion of strong-field nanoemitter technology, with practical applications in sensing, quantum optics, ultrafast electronics and high-harmonic generation from solid surfaces.

Research from Nature Portfolio

Recent experiments have tracked coherent electron oscillations within nanodevices in real time by recording photo-assisted tunnelling currents in bowtie nanoantennas, quantifying linear and nonlinear contributions and demonstrating phase control with femtosecond precision. Foundational studies on dielectric nanospheres showed that tuning the carrier-envelope phase steers recollision electrons directionally, even in regimes dominated by nonlinear charge interactions, paving the way for attosecond-resolved control of near-field emission. More recently, plasmonic gold nanostructures with sub-5 nm tips have enabled all-optical switching and momentum-space mapping of femtosecond photocurrents, with combined classical and quantum models elucidating field enhancement effects and tip-selective excitation of multiphoton photoemission.

Strong-Field Photoemission from Nanoscale Electron Sources publication trend

The graph below shows the total number of articles in strong-field photoemission from nanoscale electron sources across all publications each year (not limited to Nature Index journals).

Technical terms

Strong-field regime: Optical intensities high enough that the electric field of the light approaches or exceeds the atomic or material Coulomb field, enabling tunnelling emission.

Near-field enhancement: Local amplification of an optical field in the immediate vicinity of a nanostructure, arising from geometric or plasmonic effects.

Multiphoton photoemission: Electron emission resulting from the simultaneous absorption of two or more photons whose combined energy exceeds the work function.

Tunnelling emission: Quantum-mechanical process by which electrons escape a potential barrier under the influence of a strong optical or static field.

Carrier-envelope phase: Relative phase between the envelope of an ultrashort laser pulse and its underlying optical carrier oscillation, crucial for sub-cycle control.

Recollision: Phenomenon in which an emitted electron is driven back by the optical field to re-encounter its parent structure, enabling high-harmonic generation or secondary emission processes.

References

1. Real-time tracking of coherent oscillations of electrons in a nanodevice by photo-assisted tunnelling. Nature Communications (2024).
2. Light-Induced Subnanometric Modulation of a Single-Molecule Electron Source. Physical Review Letters (2023).
3. Attosecond physics phenomena at nanometric tips. Journal of Physics B Atomic Molecular and Optical Physics (2018).
4. Field propagation-induced directionality of carrier-envelope phase-controlled photoemission from nanospheres. Nature Communications (2015).
5. Interaction of ultrashort laser pulses with metal nanotips: a model system for strong-field phenomena. New Journal of Physics (2012).
6. Plasmonic nanostar photocathodes for optically-controlled directional currents. Nature Communications (2020).