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Plasmonic nanogaps for broadband and large spontaneous emission rate enhancement

Edwards, Anthony P.; Adawi, Ali M.


Anthony P. Edwards


We present the optical properties of a plasmonic nanogap formed between a silver metallic nanoparticle and an extended silver film that shows a strong enhancement in the spontaneous emission rate over the whole visible range. In particular, we use three-dimensional finite difference time domain calculations to study the spontaneous emission rate and the quantum efficiency of an emitting material placed within the gap region as a function of the geometrical parameters of the plasmonic nanogap. Our calculations reveal that the enhancements in the total decay rate can be divided into two regions as a function of wavelength; region I spans the wavelength range from 350 nm to 500 nm and peaks at approximately at 400 nm. Region II covers the spectral range between 500 nm and 1000 nm. The enhancements in total decay rate in region I are mainly dominated by Ohmic losses by the metal, while the enhancements in total decay rate in region II are mainly dominated by radiative decay rate enhancements. Furthermore, our calculations show over 100 times enhancement in the spontaneous emission rate in region II. We combine this with quantum efficiency enhancements of almost 30 times from materials with low intrinsic quantum efficiencies and only a small reduction in efficiency from those with high intrinsic quantum efficiencies. All results appear easily achievable using realistic geometrical parameters and simple synthesis techniques. These results are attributed to the strong field confinements in the nanogap region. The structures are of high interest for both the fundamental understanding of light mater interactions under extreme electromagnetic field confinements and also potential applications in quantum optics and Raman spectroscopy.


Edwards, A. P., & Adawi, A. M. (2014). Plasmonic nanogaps for broadband and large spontaneous emission rate enhancement. Journal of applied physics, 115(5), Article ARTN 053101.

Acceptance Date Jan 21, 2014
Online Publication Date Feb 4, 2014
Publication Date Feb 7, 2014
Deposit Date Oct 27, 2015
Publicly Available Date Nov 23, 2017
Journal Journal of applied physics
Print ISSN 0021-8979
Electronic ISSN 1089-7550
Publisher American Institute of Physics
Peer Reviewed Peer Reviewed
Volume 115
Issue 5
Article Number ARTN 053101
Keywords Silver; Radiative decays; Nanoparticles; Plasmons; Laser efficiency
Public URL
Publisher URL
Additional Information The following article appeared in: Journal of Applied Physics 115, 053101 (2014); doi: 10.1063/1.4864018 and may be found at:


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© 2014 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.

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