Harmonic Resonance Enhanced Second-Harmonic Generation in the Monolayer WS<sub>2</sub>–Ag Nanocavity
Bibliographic record
Abstract
The enhanced second-harmonic generation (SHG) from a monolayer WS2 coupled to a plasmonic nanocavity is experimentally and theoretically investigated. The nanocavity is comprised of monodispersed Ag nanocubes separated from an Ag film by a spacer Al2O3, namely, the nanoparticle on mirror (NPoM) system. When the surface plasmon polariton resonance (SPPR) wavelength of NPoM nanocavity overlaps well with the SHG wavelength of the monolayer WS2 (namely, harmonic resonance), a ∼300-fold SHG enhancement is achieved in experiment. For theoretical understanding, the quantum mechanical density matrix method has been used to develop a theory for SHG. It is found that the SHG intensity of nanohybrid is proportional to the square of the local-field intensity in NPoM nanocavity at SHG wavelength, which is ascribed to the dipole–quadrupole interaction between dipole, PSHG, in the monolayer WS2 and quadrupole, QAg, in Ag nanocavity. It is significantly different from that in metal nanoparticles under harmonic resonance, which is proportional to the local-field intensity. Therefore, it provides a novel mechanism for enhancing SHG signals from metal–semiconductor nanohybrids, which has potential applications in nonlinear devices and hybrid nonlinear metasurfaces.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.001 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".