Band-Selective LDOS Engineering of Yb/Er Upconversion: an Electromagnetic-Kinetic Diagnostic Framework
Abstract
A persistent challenge in plasmonic upconversion is decoupling pump-field enhancement from emission-side local-density-of-optical-states (LDOS) engineering to achieve selective band manipulation. Here, we show that a corrugated SU₈/Au/Al₂O₃ grating coated with a NaYF 4 : Yb/Er upconversion nanoparticle (UCNP) monolayer realizes a truly band-selective platform. A broad plasmonic resonance near 670 nm modulates the red Er³⁺ decay rate by ±15% as a function of the Al₂O₃ spacer thickness, while leaving the green transition experimentally invariant (< 1% change). Simultaneously, the 980 nm pump field is monotonically suppressed below free-space levels, ensuring that steady-state and time-resolved observables cleanly probe the emission-side LDOS without pump interference. We analyze this system using a coupled electromagnetic-kinetic framework that integrates finite-difference time-domain (FDTD) calculations of Purcell factors and pump fields with a six-level Yb/Er rate-equation model. The framework quantitatively reproduces the 670 nm plasmonic resonance, the red-band decay-rate modulation, and the monotonic decrease of the green/red intensity ratio. Crucially, the model serves as a powerful diagnostic tool: it overpredicts a green-band rate reduction, but systematic parametric testing rules out geometric (apex smoothing) and material (grain-boundary damping, interband loss) imperfections as the cause. Instead, it isolates the residual discrepancy to measurement-versus-model factors (finiteaperture angular averaging) and missing non-radiative kinetic channels, establishing a clear roadmap for the rational design and validation of future plasmonic-UCNP architectures.
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BibTeX
@article{zhang2026bandselective,
title = {{Band-Selective LDOS Engineering of Yb/Er Upconversion: an Electromagnetic-Kinetic Diagnostic Framework}},
author = {Yuxiang Zhang and Mayte Gómez-Castaño and Agustín Mihi and Serge Ravaine and Xiaogang Liu and Renaud Vallée},
journal = {ACS photonics},
year = {2026},
month = aug,
doi = {10.1021/acsphotonics.6c01114},
eprint = {2605.04872},
archivePrefix = {arXiv},
url = {https://hal.science/hal-05760805v1},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - JOUR
TI - Band-Selective LDOS Engineering of Yb/Er Upconversion: an Electromagnetic-Kinetic Diagnostic Framework
AU - Yuxiang Zhang
AU - Mayte Gómez-Castaño
AU - Agustín Mihi
AU - Serge Ravaine
AU - Xiaogang Liu
AU - Renaud Vallée
PY - 2026
DA - 2026/08/24
JO - ACS photonics
DO - 10.1021/acsphotonics.6c01114
UR - https://hal.science/hal-05760805v1
AB - A persistent challenge in plasmonic upconversion is decoupling pump-field enhancement from emission-side local-density-of-optical-states (LDOS) engineering to achieve selective band manipulation. Here, we show that a corrugated SU₈/Au/Al₂O₃ grating coated with a NaYF 4 : Yb/Er upconversion nanoparticle (UCNP) monolayer realizes a truly band-selective platform. A broad plasmonic resonance near 670 nm modulates the red Er³⁺ decay rate by ±15% as a function of the Al₂O₃ spacer thickness, while leaving the green transition experimentally invariant (< 1% change). Simultaneously, the 980 nm pump field is monotonically suppressed below free-space levels, ensuring that steady-state and time-resolved observables cleanly probe the emission-side LDOS without pump interference. We analyze this system using a coupled electromagnetic-kinetic framework that integrates finite-difference time-domain (FDTD) calculations of Purcell factors and pump fields with a six-level Yb/Er rate-equation model. The framework quantitatively reproduces the 670 nm plasmonic resonance, the red-band decay-rate modulation, and the monotonic decrease of the green/red intensity ratio. Crucially, the model serves as a powerful diagnostic tool: it overpredicts a green-band rate reduction, but systematic parametric testing rules out geometric (apex smoothing) and material (grain-boundary damping, interband loss) imperfections as the cause. Instead, it isolates the residual discrepancy to measurement-versus-model factors (finiteaperture angular averaging) and missing non-radiative kinetic channels, establishing a clear roadmap for the rational design and validation of future plasmonic-UCNP architectures.
SN - 2330-4022
ER -