Title: Optical antenna enhanced spontaneous emission

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, I(o) = qω|x(o)|/d, feeding the antenna-enhanced spontaneous emission, where q|x(o)| 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. Additionally, plasmonic effects are minor at 200 THz, producing only a small shift of antenna resonance frequency.

Authors:

Eggleston, Michael S. ^[1]; Messer, Kevin ^[1]; Zhang, Liming ^[2]; Yablonovitch, Eli ^[1]; Wu, Ming C. ^[1]

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+ Show Author Affiliations

1. Electrical Engineering and Computer Sciences Department, University of California, Berkeley, CA 94720, and
2. Bell Labs, Alcatel-Lucent, Holmdel, NJ 07733

Publication Date:

Mon Jan 26 00:00:00 EST 2015

Research Org.:

University of California, Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES)

OSTI Identifier:

1235502

Alternate Identifier(s):

OSTI ID: 1347700

Grant/Contract Number:  

AC02-05CH11231

Resource Type:

Published Article

Journal Name:

Proceedings of the National Academy of Sciences of the United States of America

Additional Journal Information:

Journal Name: Proceedings of the National Academy of Sciences of the United States of America Journal Volume: 112 Journal Issue: 6; Journal ID: ISSN 0027-8424

Publisher:

Proceedings of the National Academy of Sciences

Country of Publication:

United States

Language:

English

Subject:

74 ATOMIC AND MOLECULAR PHYSICS; 77 NANOSCIENCE AND NANOTECHNOLOGY; metal optics; nanophotonics; plasmonics; ultrafast devices