Increased Fluorescence of PbS Quantum Dots in Photonic Crystals by Excitation Enhancement

TL;DR

This study demonstrates that silicon photonic crystal slabs can significantly enhance the fluorescence of PbS quantum dots through excitation enhancement, with potential applications in biosensing and solar energy.

Contribution

It introduces a method to enhance quantum dot fluorescence using leaky modes in photonic crystals, supported by experimental and numerical evidence.

Findings

Enhanced fluorescence observed at specific resonances

Numerical simulations confirm near-field enhancement effects

Potential for improved biosensing and energy conversion devices

Abstract

We report on enhanced fluorescence of lead sulfide quantum dots interacting with leaky modes of slab-type silicon photonic crystals. The photonic crystal slabs were fabricated supporting leaky modes in the near infrared wavelength range. Lead sulfite quantum dots which are resonant the same spectral range were prepared in a thin layer above the slab. We selectively excited the leaky modes by tuning wavelength and angle of incidence of the laser source and measured distinct resonances of enhanced fluorescence. By an appropriate experiment design, we ruled out directional light extraction effects and determined the impact of enhanced excitation. Three-dimensional numerical simulations consistently explain the experimental findings by strong near-field enhancements in the vicinity of the photonic crystal surface. Our study provides a basis for systematic tailoring of photonic crystals used in biological applications such as biosensing and single molecule detection, as well as quantum dot solar cells and spectral conversion applications.