Double-Layer Metasurface for Enhanced Photon Up-Conversion

TL;DR

This paper introduces a double-layer dielectric metasurface that significantly enhances photon up-conversion efficiency through resonant near-field effects and light trapping, with potential applications in solar energy and biosensing.

Contribution

It demonstrates the design and experimental validation of a double-layer metasurface that boosts up-conversion photoluminescence by 2.7 times, revealing new mechanisms for light manipulation.

Findings

2.7-fold increase in up-conversion photoluminescence.

Splitting and broadening of Rayleigh-Wood anomalies in multilayer metasurfaces.

Enhanced near-fields and light trapping contribute to efficiency improvements.

Abstract

We present a double-layer dielectric metasurface obtained by stacking a silicon nanodisc array and a silicon photonic crystal slab with equal periodicity on top of each other. We focus on the investigation of electric near-field enhancement effects occurring at resonant excitation of the metasurface and study its optical properties numerically and experimentally. We find that the major difference in multi-layer metasurfaces when compared to conventional single-layer structures appears to be in Rayleigh-Wood anomalies: they are split into multiple different modes which are themselves spectrally broadened. As a proof of concept we cover a double-layer metasurface with a lanthanide-doped up-conversion particle layer and study its interaction with a 1550 nm photoexcitation. We observe a 2.7-fold enhancemed up-conversion photoluminescence by using the stacked metasurface instead of a planar substrate, although only around 1% of the up-conversion material is exposed to enhanced near-fields. Two mechanisms are identified explaining this behavior: First, enhanced near-fields when exciting the metasurface resonantly, and second, light trapping by total internal reflection in the particle layer when the metasurface redirects light into high-angle diffraction orders. These results pave the way for low-threshold and, in particular, broadband photon up-conversion in future solar energy and biosensing applications.