Carrier Dynamics of Quantum Dot
Semiconductor Optical Amplifiers
Tyndall National Institute
2/2/2006 10:55:41
Basic Characteristics of
SOA:
-6
• Gain Saturation
• Modal gain
100mA
90mA
80mA
70mA
60mA
50mA
40mA
30mA
20mA
10mA
QD Amplifier
ASE SMF CW
7.0x10
-6
6.0x10
Power (mW)
• Amplified Spontaneous Emission,
-6
8.0x10
-6
5.0x10
-6
4.0x10
-6
3.0x10
-6
2.0x10
Pump Energy: 0.6pJ
-6
1.0x10
0.0
Probe Energy: 0.007pJ
-6
-1.0x10
1200
1250
1300
Wavelength (nm)
SOA@RT
Transmision (a.u.)
Current
200mA
195mA
190mA
...........
...........
...........
50mA
45mA
40mA
0.1
0.01
0.00164
0.01645
0.16447
1.64474
Total Input Pulse Energy (pJ)
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16.44737
1350
1400
Pump-Probe Technique
(Ref: K.L. Hall, G. Lenz, E.P. Ippen, and G. Raybon, Optical Society of America, 1992)
Pump Probe allows us to study the carrier dynamics of QD SOAs
ES
ES
GS
GS
Pump
Pump
Probe
GS
ES
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Probe
GS
ES
Experimental Set-up: Layout
8W Verdi Pump Laser
Mira Femto-second Laser
OPO
SMF-28
300fs
18nm
Collimated + Femtosecond Light Source at a central wavelength
GS
ES
ASE 175mA
1.0
1.6
1.4
OPO ~ 1280nm
P~76mW
1m SMF
8mm lens
1.2
0.6
Intensity (mW)
Normalized Power
0.8
0.4
0.2
1.0
GS
ES
0.8
0.6
0.4
0.2
1200 1220 1240 1260 1280 1300 1320 1340 1360 1380
Wavelength [nm]
1200
1220
Time Resolution of 600fs
Exchangeable filters allow single and two colour measurements
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1240
1260
1280
1300
1320
Wavelength (nm)
1340
1360
1380
1400
Experimental Set-up: Layout
8W Verdi Pump Laser
Mira Femto-second Laser
OPO
SMF-28
Lock In
Lock-In detects beating frequency
between probe and Ref
80MHz - 79MHz = 1MHz
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Experimental Set-up
A
B
C
D
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Data Analysis: The Absorption Regime
Single Colour: GS-pump, GS-probe
7
Escape processes:
Single Colour GS
I=10mA
6
(Intermediate)
G(dB)
5
4
3
2
1
0
-1
PUMP
-20
PROBE
0
20
40
60
80
100
120
140
Delay (ps)
1) Very fast time ~1ps
2) Intermediate time ~30ps
3) Slow time ~200ps
Interband recombination:
Hole redistribution:
(Slow)
(Very fast)
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Tri-exponential behaviour:
f(x)=A1*exp(-t/1)+A2*exp(-t/  2)+A3*exp(-t/  3)
The Model
5 Level Model
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•
Barrier Nb
•
Wetting Layer Nwl
•
Excited State Ne
•
Ground State Ng
•
Single Hole Level Nh
The Model: Simulations
Absorption - Experiment
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Absorption - Simulation
The Model: Simulations
Gain - Experiment
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Gain - Simulation
Summary
I.
Two color pump-probe spectroscopy has been
developed
II.
Dynamics of InAs/GaAs QD SOA has been
investigated using two colour technique
III. The main time constants of the absorption and gain
dynamics have been identified.
More information may be obtained:
‘Electron and Hole Dynamics of InAs/GaAs quantum dot semiconductor optical amplifiers’
I. O' Driscoll, T. Piwonski, C. F. Schleussner, J. Houlihan, G. Huyet and R J. Manning,
Applied Physics Letters, 91, 071111, (2007)
Carrier Capture Dynamics of InAs/GaAs Quantum Dots
T. Piwonski, I. O' Driscoll, J. Houlihan, G. Huyet, R.J. Manning and A. V. Uskov,
Applied Physics Letters, 90 (12),122108 (2007).
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