Coherent fluorescence emission by using hybrid photonic–plasmonic crystals

Abstract

The spatial and temporal coherence of the fluorescence emission controlled by a quasi-two-dimensional hybrid photonic-plasmonic crystal structure covered with a thin fluorescent-molecular-doped dielectric film is investigated experimentally. A simple theoretical model to describe how a confined quasi-two-dimensional optical mode may induce coherent fluorescence emission is also presented. Concerning the spatial coherence, it is experimentally observed that the coherence area in the plane of the light source is in excess of 49 μm 2 , which results in enhanced directional fluorescence emission. Concerning temporal coherence, the obtained coherence time is 4 times longer than that of the normal fluorescence emission in vacuum. Moreover, a Young's double-slit interference experiment is performed to directly confirm the spatially coherent emission. This smoking gun proof of spatial coherence is reported here for the first time for the optical-mode-modified emission. Starting with non-coherent fluorescent emission, high degree of spatial and temporal coherent emission is produced assisted by quasi-two-dimensional optical modes. The Young's double-slit experiments directly reveal spectral coherence length at least 10 times longer than the emission wavelength. The findings show that modifying the coherence properties of the fluorescent emission is possible by using hybrid photonic-plasmonic structures. © 2014 The Authors. Laser & Photonics Reviews published by Wiley-VCH Verlag GmbH & Co. KGaA Weinheim.