Optical antenna enhanced spontaneous emission
- 26 January 2015
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences of the United States of America
- Vol. 112 (6), 1704-1709
- https://doi.org/10.1073/pnas.1423294112
Abstract
Atoms and molecules are too small to act as efficient antennas for their own emission wavelengths. By providing an external optical antenna, the balance can be shifted; spontaneous emission could become faster than stimulated emission, which is handicapped by practically achievable pump intensities. In our experiments, InGaAsP nanorods emitting at ∼200 THz optical frequency show a spontaneous emission intensity enhancement of 35× corresponding to a spontaneous emission rate speedup ∼115×, for antenna gap spacing, d = 40 nm. Classical antenna theory predicts ∼2,500× spontaneous emission speedup at d ∼ 10 nm, proportional to 1/d2. Unfortunately, at d < 10 nm, antenna efficiency drops below 50%, owing to optical spreading resistance, exacerbated by the anomalous skin effect (electron surface collisions). Quantum dipole oscillations in the emitter excited state produce an optical ac equivalent circuit current, Io = qω|xo|/d, feeding the antenna-enhanced spontaneous emission, where q|xo| is the dipole matrix element. Despite the quantum-mechanical origin of the drive current, antenna theory makes no reference to the Purcell effect nor to local density of states models. Moreover, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency.Keywords
Funding Information
- National Science Foundation (ECCS-0939514)
- DOD | Air Force Office of Scientific Research (FA9550-09-1-0598)
- | Basic Energy Sciences (DE-AC02-05CH11231)
This publication has 44 references indexed in Scilit:
- Spontaneous emission enhancement of a single molecule by a double-sphere nanoantenna across an interface.Optics Express, 2012
- Giant and uniform fluorescence enhancement over large areas using plasmonic nanodots in 3D resonant cavity nanoantenna by nanoimprintingNanotechnology, 2012
- Accelerated single photon emission from dye molecule-driven nanoantennas assembled on DNANature Communications, 2012
- Antennas for lightNature Photonics, 2011
- Large single-molecule fluorescence enhancements produced by a bowtie nanoantennaNature Photonics, 2009
- Nanoantenna array-induced fluorescence enhancement and reduced lifetimesNew Journal of Physics, 2008
- Modification of single molecule fluorescence close to a nanostructure: radiation pattern, spontaneous emission and quenchingMolecular Physics, 2008
- Strong Enhancement of the Radiative Decay Rate of Emitters by Single Plasmonic NanoantennasNano Letters, 2007
- Spectral dependence of single molecule fluorescence enhancementOptics Express, 2007
- Heinrich Hertz and the Development of PhysicsPhysics Today, 1989