Giant second-harmonic generation in few-atomic layer metals
Abstract
Quantum confinement restructures the electronic phase space of ultrathin metals, but the resulting density-of-states (DOS) change is not generically large. We show that, within a three-dimensional confinement theory based on the suppression of long-wavelength electronic states, the Fermi-level DOS enhancement on the weak-confinement branch is bounded by (4/3)1/3−1≃10.1%. Instead, confinement-induced redistribution of electronic phase space can be strongly amplified by resonant denominators in the second-order susceptibility. A minimal double-resonance closure predicts giant amplification when the film thickness approaches Lc=(2π/n)1/3, where n is the carrier density, and a dominant optical pathway lies within a dephasing linewidth of resonance. Applied to recent Ag(111) measurements, the theory gives an effective phase-space carrier density parameter neff≃3.6×1020 cm−3, a tenfold enhancement of |χ(2)|, and hence the observed ∼100-fold increase of thickness-normalized second-harmonic-generation efficiency, together with the observed non-oscillatory thickness dependence.
Related
- Automated mode-aware design of nonlinear photonic crystal cavities for intrinsic second harmonic generation
- Characterization of YAl₃(BO₃)₄ nonlinear properties for second harmonic generation in the green and UV ranges
- Deep-ultraviolet second-harmonic generation in a three-coherence-length SrB ₄ O ₇ microcavity
- Destructive interference of second harmonic generation in AA-stacked MoTe 2 /WSe 2
- Giant third-order nonlinearity amplifies second-harmonic transport in Ca3Ru2O7
BibTeX
@misc{zaccone2026giant,
title = {{Giant second-harmonic generation in few-atomic layer metals}},
author = {Alessio Zaccone},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.14468},
eprint = {2609.14468},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.14468},
}
RIS
TY - UNPB
TI - Giant second-harmonic generation in few-atomic layer metals
AU - Alessio Zaccone
PY - 2026
DA - 2026/09/13
PB - arXiv
DO - 10.48550/arxiv.2609.14468
UR - https://arxiv.org/abs/2609.14468
AB - Quantum confinement restructures the electronic phase space of ultrathin metals, but the resulting density-of-states (DOS) change is not generically large. We show that, within a three-dimensional confinement theory based on the suppression of long-wavelength electronic states, the Fermi-level DOS enhancement on the weak-confinement branch is bounded by (4/3)^1/3−1≃10.1%. Instead, confinement-induced redistribution of electronic phase space can be strongly amplified by resonant denominators in the second-order susceptibility. A minimal double-resonance closure predicts giant amplification when the film thickness approaches L_c=(2π/n)^1/3, where n is the carrier density, and a dominant optical pathway lies within a dephasing linewidth of resonance. Applied to recent Ag(111) measurements, the theory gives an effective phase-space carrier density parameter n_eff≃3.6×10^20 cm^−3, a tenfold enhancement of |χ^(2)|, and hence the observed ∼100-fold increase of thickness-normalized second-harmonic-generation efficiency, together with the observed non-oscillatory thickness dependence.
ER -