ULTRAFAST CONTROL OF POLARITON STIMULATED SCATTERING IN SEMICONDUCTOR MICROCAVITIES Cornelius...
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Transcript of ULTRAFAST CONTROL OF POLARITON STIMULATED SCATTERING IN SEMICONDUCTOR MICROCAVITIES Cornelius...
![Page 1: ULTRAFAST CONTROL OF POLARITON STIMULATED SCATTERING IN SEMICONDUCTOR MICROCAVITIES Cornelius Grossmann1 G. Christmann, C. Coulson and J.J. Baumberg Nanophotonics.](https://reader033.fdocuments.net/reader033/viewer/2022051515/551b2f7b550346dd1a8b4d53/html5/thumbnails/1.jpg)
Cornelius Grossmann 1
ULTRAFAST CONTROL OF POLARITON STIMULATED SCATTERING IN SEMICONDUCTOR MICROCAVITIES
Cornelius Grossmann
G. Christmann, C. Coulson and J.J. BaumbergNanophotonics Centre, Cavendish Laboratory, University of Cambridge
N. T. Pelekanos, Z. Hatzopoulos, S. I. Tsinzos and P. G. SavvidisDepartment of Materials Science and Technology, University of Crete
PLMCN10, Cuernavaca, Mexico15th april 2010
![Page 2: ULTRAFAST CONTROL OF POLARITON STIMULATED SCATTERING IN SEMICONDUCTOR MICROCAVITIES Cornelius Grossmann1 G. Christmann, C. Coulson and J.J. Baumberg Nanophotonics.](https://reader033.fdocuments.net/reader033/viewer/2022051515/551b2f7b550346dd1a8b4d53/html5/thumbnails/2.jpg)
Cornelius Grossmann 2
Strong coupling regime
Mirror MirrorActiveregion
C. Weisbuch et al., PRL 69 3314 (1992)
|excited,0> |ground,1>
h
Lower polariton
Upper polariton
Strong-coupling regime:reabsorption time < cavity lifetime
semiconductor microcavity
Exciton
Cavity
UPB
LPB
Energy
Momentum
coupling between a electronic transition and a Fabry-Perot mode
![Page 3: ULTRAFAST CONTROL OF POLARITON STIMULATED SCATTERING IN SEMICONDUCTOR MICROCAVITIES Cornelius Grossmann1 G. Christmann, C. Coulson and J.J. Baumberg Nanophotonics.](https://reader033.fdocuments.net/reader033/viewer/2022051515/551b2f7b550346dd1a8b4d53/html5/thumbnails/3.jpg)
Cornelius Grossmann 3
Parametric scattering processparametric conversion:• probe stimulation at ks= 0• energy and momentum conservation!
Savvidis et. al., PRL 84 1547 (2000)
• coherent χ(3) process in semiconductor microcavities• χ(3)-nonlinearity: exciton-exciton interaction• probe gain highly dependent on pump-LPB resonance
2kp= ks+ki
2E(kp)= E(ks)+E(ki)
PumpEP, kP
EI, kI
ES, kS
Signal
Idler
χ(3)
![Page 4: ULTRAFAST CONTROL OF POLARITON STIMULATED SCATTERING IN SEMICONDUCTOR MICROCAVITIES Cornelius Grossmann1 G. Christmann, C. Coulson and J.J. Baumberg Nanophotonics.](https://reader033.fdocuments.net/reader033/viewer/2022051515/551b2f7b550346dd1a8b4d53/html5/thumbnails/4.jpg)
Cornelius Grossmann 4
Under external bias
Polariton light emitting diode
D. Tsintzos et al., Nature 453 372 (2008)
Quantum confined Stark effect
conductionband
valence band
GaAs InGaAs GaAs
Growth axis
F
Applied bias
consequences
change of energy of excitonic transition separation of electron and hole wavefunctions
![Page 5: ULTRAFAST CONTROL OF POLARITON STIMULATED SCATTERING IN SEMICONDUCTOR MICROCAVITIES Cornelius Grossmann1 G. Christmann, C. Coulson and J.J. Baumberg Nanophotonics.](https://reader033.fdocuments.net/reader033/viewer/2022051515/551b2f7b550346dd1a8b4d53/html5/thumbnails/5.jpg)
Cornelius Grossmann 5
Electrically pumped polariton devices
Optical bistability in GaAs-based Polariton LED
Bajoni et. al., PRL 101 266402 (2008)
Electroluminescence up to RT
Tsintzos et. al., APL 94 071109 (2009)Khalifa et. al., APL 92 061107 (2008)Bajoni et. al., PRB 77 113303 (2008)
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Cornelius Grossmann 6
Motivation for the bias
The parametric scattering process is due to exciton-exciton interaction through χ(3)
-+
-+
- +
- +
The excitons are alignedTailoring of the exciton-exciton interaction
Consequences on the parametric amplification in microcavities?
Growth axis
F
![Page 7: ULTRAFAST CONTROL OF POLARITON STIMULATED SCATTERING IN SEMICONDUCTOR MICROCAVITIES Cornelius Grossmann1 G. Christmann, C. Coulson and J.J. Baumberg Nanophotonics.](https://reader033.fdocuments.net/reader033/viewer/2022051515/551b2f7b550346dd1a8b4d53/html5/thumbnails/7.jpg)
Cornelius Grossmann 7
Experimental setup
fs mode-locked Ti:Sa laser system• pump spectrally filtered and broadband probe pulse• pump at the magic-angle• probe at k||= 0 • recording of
pump reflected spectrum incident probe reflected probe
• in parallel: electrical measurements
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Cornelius Grossmann 8
Voltage scan: Stark effect
Ref
lect
ivity
(arb
. uni
ts)
1.4161.4121.4081.404
Energy (eV)
2.5V
-2.4V
T=7.5 K LP
X
UP
C
1
1.416
1.414
1.412
1.410
1.408
1.406
1.404
1.402
1.400
En
erg
y (
eV
)
210-1
Bias (V)
Stark tuning of the excitonsRabi splitting of 6 meV
Refle
ction
spe
ctra
![Page 9: ULTRAFAST CONTROL OF POLARITON STIMULATED SCATTERING IN SEMICONDUCTOR MICROCAVITIES Cornelius Grossmann1 G. Christmann, C. Coulson and J.J. Baumberg Nanophotonics.](https://reader033.fdocuments.net/reader033/viewer/2022051515/551b2f7b550346dd1a8b4d53/html5/thumbnails/9.jpg)
Cornelius Grossmann 9
Voltage scan: pump-probe
50
40
30
20
10
0
Gain
1.4161.4121.4081.404
Energy (eV)
Ipump
2.5V
-1.5V
c)
a)b)
LP(kp)
LP
UP
10
8
6
4
2
0
Peak
gain
210-1
Bias (V)
1.416
1.414
1.412
1.410
1.408
1.406
1.404
Energ
y (eV
)
210-1
Bias (V)
2 effects: • gain-loss at negative bias, dispersion-less
50
40
30
20
10
0
Gai
n
1.4161.4121.4081.404
Energy (eV)Ip
um
p
2.5V
-1.5V
c)
a)b)
LP(kp)
LP
UP
10
8
6
4
2
0
Pea
k g
ain
210-1
Bias (V)
1.416
1.414
1.412
1.410
1.408
1.406
1.404
Ene
rgy
(eV
)
210-1
Bias (V)
50
40
30
20
10
0
Gai
n
1.4161.4121.4081.404
Energy (eV)
Ipump
2.5V
-1.5V
c)
a)b)
LP(kp)
LP
UP
10
8
6
4
2
0
Pea
k ga
in
210-1
Bias (V)
1.416
1.414
1.412
1.410
1.408
1.406
1.404
Ene
rgy
(eV
)
210-1
Bias (V)
500
0
Cu
rren
t (
A)
-2 0 2Bias (V)
Cu
rren
t (μ
A)
Bias (V)
pump onpump off
gain-loss at negative bias:detuning of pump and LPB
• gain dip at positive bias
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Cornelius Grossmann 10
Negative bias: gain loss
• unbiased
• biased
Stark-tuning of excitons:pump out of resonance with LPB inefficient carrier injection
resonance of pump and LPB:efficient parametric amplification efficient carrier injection
Growth axis
No screening of external electric field!
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Cornelius Grossmann 11
sharp gain dip
-20
-15
-10
-5
0
Curre
nt (
A)
1.00.80.60.4
Bias (V)
x6
c)
a) b)
1.1 V
0.4 V
80
60
40
20
0
Gain
1.4121.4111.4101.4091.4081.407
Energy (eV)
40
30
20
10
0
Peak
gain
1.00.80.60.4Bias (V)
-20
-15
-10
-5
0
Curre
nt (A
)
1.00.80.60.4
Bias (V)
x6
c)
a) b)
1.1 V
0.4 V
80
60
40
20
0
Gain
1.4121.4111.4101.4091.4081.407
Energy (eV)
40
30
20
10
0
Peak g
ain
1.00.80.60.4Bias (V)
100 mV
> 90%
sharp dip
additionalphotocurrentat this bias
50
40
30
20
10
0
Gai
n
1.4161.4121.4081.404
Energy (eV)
Ipump
2.5V
-1.5V
c)
a)b)
LP(kp)
LP
UP
10
8
6
4
2
0
Pea
k ga
in
210-1
Bias (V)
1.416
1.414
1.412
1.410
1.408
1.406
1.404
Ene
rgy
(eV
)
210-1
Bias (V)
![Page 12: ULTRAFAST CONTROL OF POLARITON STIMULATED SCATTERING IN SEMICONDUCTOR MICROCAVITIES Cornelius Grossmann1 G. Christmann, C. Coulson and J.J. Baumberg Nanophotonics.](https://reader033.fdocuments.net/reader033/viewer/2022051515/551b2f7b550346dd1a8b4d53/html5/thumbnails/12.jpg)
Cornelius Grossmann 12
Tunneling
-1.20
-1.16
-1.12
-1.08En
erg
y (
eV
)
40200Position (nm)
0.40
0.36
0.32
0.28
LP
LQW RQW
τc
τe
τtτLO
τΩ
τo
700fs8ps
20ps
2 competing processes• Rabi-oscillations: redistribution of e-/h-pairs over QWs • carrier tunneling: separation of e-/h-pairs
• LO-phonon induced tunneling 100 fs• carrier escape 180 ns, 230 fs• extra e- population creates extra scattering• OPO gain sensitive to broadening
C. Ciuti et al. PRB 62 R4825 (2000)
0.6
0.51.00.5
Bias (V)
LQW RQW
ωLO
Ee (eV)
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Cornelius Grossmann 13
Summary & outlook
electrical control of the parametric gain sharp and dramatic gain modulation
Stark tuning with “small” electrical fields: ultrafast response expected Potential realization of Thz modulators?
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Cornelius Grossmann 14
Support and funding
• Pavlos G. Savvidis et. al.: Polariton LED sample• Gabriel Christmann, Chris Coulson and Jeremy Baumberg: spectroscopy & simulation
Funding: • UK EPSRC EP/C511786/1, EP/F011393 • EU Clermont 4