Strong purcell enhancement of er atoms embedded in metallic nano-cavity

Abstract

We demonstrate strong Purcell enhancement on erbium atoms embedded in a gold nano-trench struc-ture. Gold nano-trench is a rectangular half-cavity inside SiO2 media that supports large enhancement of elec-tric fields along the direction of small nano-gap (~50 nm) through surface plasmon resonance it bears. The fields concentrated on the dielectric region inside the gold nano-trench enables erbiums to obtain large Purcell enhancement while relieving the effect of quenching by virtue of emitter-metal boundary separation (>20 nm for erbiums at the center). Time-resolved photoluminescence measurement shows the average decay rate of erbiums inside the gold nano-trench is enhanced by a factor of 130 which is the world best and is equivalent to the result of corresponding numerical calculations by finite-difference-time-domain method. The congruence between the experimental results and numerical simulations can be attributed to the well-controlled fabrication of trenches of uniform gap-size (<5 nm fluctuation) as well as the large coupling between erbiums and the gold nano-trench which operates in single resonant mode.