[论文解读] Multi-wavelength UV Upconversion in Lanthanides assisted by Photonic Crystals

Damien Rinnert, Drouard, Emmanuel+7 more|arXiv (Cornell University)|Jan 23, 2026

Luminescence Properties of Advanced Materials被引用 0

一句话总结

论文展示了通过光子晶体薄膜在慢光布洛赫模和增强的ESA下，将多波长（近红外和可见）激发耦合到紫外发射，实现Yb3+-Tm3+ 共掺Y2O3 薄膜紫外上转换的28倍增强。

ABSTRACT

Upconversion luminescence consists of the absorption of low-energies photons followed by the emission of a higher energy photon. The process has mainly been studied in lanthanides to upconvert monochromatic near-infrared excitation to near-infrared or visible light, and has been exploited only to a limited extent to upconvert broad excitations to ultra-violet. In addition, upconverting near-infrared and visible light to ultra-violet is crucial for applications such as solar-to-fuel conversion or environmental remediation. However, upconversion luminescence is limited by the low absorption cross-sections of lanthanides. In this work, we engineered Bloch modes in a photonic crystal to assist a multi-wavelength upconversion mechanism and demonstrated a 28-fold enhancement of ultra-violet upconversion luminescence of Yb3+-Tm3+ doped thin films. Materials were selected and optimized to design nanostructures without parasitic absorption losses. The geometric parameters of the photonic crystals were scanned to match a slow-light resonance with an excited-state transition of Tm3+ and thus enhance incident visible light absorption. Ultra-violet light extraction was also enhanced by photonic crystal Bloch modes. Each of these two contributions were quantified and the measured photonic band structures were well reproduced by electromagnetic simulations.

研究动机与目标

• 在稀土掺杂薄膜中研究来自近红外和可见激发到紫外的多波长上转换。
• 设计光子晶体布洛赫模以增强吸收与发射，尽量减少寄生损耗。
• 量化可见光吸收与紫外提取对整体紫外上转换增强的贡献。
• 展示布洛赫模可调性，以对齐特定稀土跃迁。
• 用电磁仿真与带结构测量验证实验结果。

提出的方法

• 通过脉冲激光沉积在熔融石英上制备Y2O3:Yb3+,Tm3+ 薄膜。
• 沉积144 nm的SiNx顶层，形成240–280 nm范围内的方晶格光子晶体，p 值。
• 使用RCWA设计光子晶体参数，使慢光Γ点共振耦合到Tm3+的3F4→1D2 ESA。
• 对22个PhC区域进行模式化，晶格参量约为259–267 nm，在995 nm近红外和447 nm可见激发下测量紫外上转换发光。
• 表征带结构与反射率，以识别TE0/TM0慢光共振及其与Tm3+吸收光谱的重叠。
• 通过与未图案化参考样品比较，提取增强因子（EF），并分离可见光吸收与紫外提取的贡献。

Figure 1: Multi-wavelength UV UCL mechanism in Yb 3+ -Tm 3+ . It involves 1 NIR photon absorption by Yb 3+ ( 7 F 7/2 $\rightarrow$ 7 F 5/2 ), whose energy is transferred to Tm 3+ ( 3 F 4 ), followed by 1 visible excited state absorption in Tm 3+ ( 3 F 4 $\rightarrow$ 1 D 2 ). UV emission is obtained

实验结果

研究问题

• RQ1 多波长激发（近红外+可见）是否能在Yb3+/Tm3+ 共掺体系中增强紫外上转换？
• RQ2 在激发和发射波长处的光子晶体布洛赫模是否能在无寄生损耗的前提下增强UCL？
• RQ3 可见吸收与紫外提取对整体紫外上转换增强的相对贡献是多少？
• RQ4 晶格参数的调控如何影响慢光共振及其与Tm3+ 3F4→1D2 转换的重叠？
• RQ5 观测到的增强是否与多光子幂律机制（nNIR = nvis = 1）下的紫外发射一致？

主要发现

• 在近红外+可见激发下，紫外发射比参考高出最多28.1±3.0倍。
• 可见慢光共振提升ESA过程的因子为10.4±2.2，进而提升紫外上转换。
• 紫外光的提取被布洛赫模增强，贡献因子为2.71±0.5。
• 测得的紫外上转换遵循幂律关系，nNIR = nvis = 1，验证了多波长机制。
• 带结构测量与RCWA仿真一致，确认Γ点处设计的慢光布洛赫模。
• PhC设计实现显著的紫外上转换增强，同时最大程度降低寄生吸收。

Figure 2: Presentation of the PhC structure. (a) 3D scheme of the PhC design and operational principle: NIR and visible light absorption close to normal incidence and UV emission in a controlled direction. (b) SEM top view image of a fabricated PhC with the following parameters: period p = 267.3 $\p