Quantum electrodynamic effects in semiconductor microcavities - Microlasers and coherent exciton-polariton emission

TLDR: In this paper, the spontaneous emission of quantum well excitons in a monolithic microcavity was studied and when the quantum well was excited by a nonresonant pump wave at high above the bandgap, the incoherent spontaneous emission was concentrated on the single resonant mode and the laser threshold was reduced by many orders of magnitude.

Abstract: We discuss the spontaneous emission of quantum well excitons in a monolithic microcavity. When the quantum well is excited by a nonresonant pump wave at high above the bandgap, the incoherent spontaneous emission is concentrated on the single resonant mode and the laser threshold is reduced by many orders of magnitude. When the quantum well exciton is excited by a resonant pump wave, the coherent spontaneous emission based on a «microcavity exciton-polariton» is observed. The spectral linewidth and the polarization of the pump wave are preserved and the coupling efficiency into the single resonant mode approaches 100%. The microcavity-induced normal mode splitting is observed in the frequency domain by photoexcitation spectrum measurements and in the time domain by pump-probe measurements

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Quantum electrodynamic eects in semiconductor
microcavities - Microlasers and coherent
exciton-polariton emission
Y. Yamamoto, F. Matinaga, S. Machida, A. Karlsson, J. Jacobson, G. Björk,
T. Mukai
To cite this version:
Y. Yamamoto, F. Matinaga, S. Machida, A. Karlsson, J. Jacobson, et al.. Quantum electrodynamic
eects in semiconductor microcavities - Microlasers and coherent exciton-polariton emission. Journal
de Physique IV Proceedings, EDP Sciences, 1993, 03 (C5), pp.C5-39-C5-46. �10.1051/jp4:1993507�.
�jpa-00251593�

JOURNAL
DE
PHYSIQUE
IV
Colloque
C5,
supplkment au Journal de Physique
11,
Volume
3,
octobre
1993
Quantum electrodynamic effects in semiconductor microcavities
-
Microlasers and coherent exciton-polariton emission
Y.
YAMAMOTO*'**,
E
MATINAGA", S. MACHIDA*,
A.
KARLSSON*',
J.
JACOBSON**,
G.
BJORK**
and
T
MUKAI*
*
NTT
Basic Research Laboratories, Musashinoshi, Tokyo 180, Japan
**
Ginzton Laboratory, Stanford University, Stanford,
CA
94305, USA.
We discuss the spontaneous emission of quantum well excitons in
a
monolithic microcav-
ity. When the quantum well is excited by a nonresonant pump wave at high above the
bandgap, the incoherent spontaneous emission is concentrated on the single resonant mode
and the laser threshold is reduced by many orders of magnitude. When the quantum well
exciton is excited
by a resonant pump wave, the coherent spontaneous emission based on
a "microcavity exciton-polariton" is observed. The spectral linewidth and the polariza-
tion of the pump wave are preserved and the coupling efficiency into the single resonant
mode approaches
100%.
The microcavity-induced normal mode splitting is observed in the
frequency domain by photoexcitation spectrum measurements and in the time domain by
pump-probe measurements.
1.
Introduction
Spontaneous emission is not a fixed property of an atom but a consequence of atom-vacuum
field coupling. The decay rate, transition energy (frequency), and radiation pattern of spontaneous
emission can be
a1tered.b~ modifying the vacuum field fluctuations in the vicinity of the radiating
system by a cavity wall. The principle, often referred to as "cavity quantum electrodynamics (cavity
QED)", is a classic theoretical problem.
A
cavity enhanced or suppressed spontaneous decay rate
was predicted by Purcell in 1946
[I].
A
cavity induced radiative energy shift was predicted by
Casimir and Polder in 1948
[2].
A
coherent coupling of an atom and single-mode vacuum field
was formulated by Jaynes and Cummings in
1963
[3]. Various coherent cavity
&ED
effects such as
reversible (or coherent) spontaneous emission, normal mode (or vacuum Rabi) splitting, and quantum
collapse and revival were predicted using the Jaynes-Cummings model
[4]. Those effects have been
observed recently using either Rydberg atoms in microwave superconductor cavities or atoms in
optical dielectric cavities
[5,
61. The spontaneous emission of quantum well (QW) excitons was also
modified by
a
monolithic microcavity [7]. Recently, the normal mode splitting was observed for the
coupled exciton and photon system in a microcavity
[8].
The normal modes in solids involving excitons and photons are "polaritons" [9], which are "sta-
tionary" (do not radiatively decay) in a bulk material without translational-invariance breaking
defects. However, for the excitons confined in a QW which inherently breaks full translational
in-
variance, the electromagnetic decay channel is open for excitons with the in-plane wavenumber
kll
lying below the crossing with the photon dispersion line
ko
=
(w/q)n.
On the other hand, the QW
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jp4:1993507