Connections 2006Connections 2006
Ultrafast Nonlinear Dynamics of Ultrafast Nonlinear Dynamics of Quantum Dot Quantum Dot
Semiconductor Optical AmplifiersSemiconductor Optical Amplifiers
In collaboration with:In collaboration with:
National Research Council National Research Council
of Canada, Ottawa, ONof Canada, Ottawa, ON
Supervisors:Supervisors:
Peter W. E. Smith Peter W. E. Smith
J. Stewart AitchisonJ. Stewart Aitchison
Aaron J. ZilkieAaron J. ZilkiePhD CandidatePhD Candidate
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OutlineOutline
1)1) Introduction and MotivationIntroduction and Motivation
2) Experimental Setup2) Experimental Setup Heterodyne pump-probe lab setupHeterodyne pump-probe lab setup
3) Ultrafast Dynamics 3) Ultrafast Dynamics Ultrafast Gain recoveryUltrafast Gain recovery
Additional Ultrafast NonlinearitiesAdditional Ultrafast Nonlinearities
4) 4) ConclusionsConclusions
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IntroductionIntroduction
Quantum Dot Semiconductor Optical Amplifiers (QD SOA)Quantum Dot Semiconductor Optical Amplifiers (QD SOA)
““Single pass laser” – light enters, experiences gain via stimulated emission as it passes Single pass laser” – light enters, experiences gain via stimulated emission as it passes throughthrough
QD SOAs predicted to have 10-100 X faster recovery times than othersQD SOAs predicted to have 10-100 X faster recovery times than others
NRC QDs Novel: First to work at 1.55 NRC QDs Novel: First to work at 1.55 μμm m telecom wavelengthstelecom wavelengths
+
-
p
n
500 nm
SEM Cross-section
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MotivationMotivation
All Optical Signal ProcessingAll Optical Signal Processing
SOA used as nonlinear switching element SOA used as nonlinear switching element Control pulses induce phase changeControl pulses induce phase change
light can switch light!light can switch light!
Nonlinear phase change
balanced
Su
pre
ssio
n
balanced
unbalanced
SOA ultrafast dynamics critically influence switching windowSOA ultrafast dynamics critically influence switching window Our Work:Our Work: Measure the ultrafast dynamics of novel QD SOAs Measure the ultrafast dynamics of novel QD SOAs
Heterodyne Heterodyne Pump-probe Pump-probe
Lab SetupLab Setup
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Heterodyne Pump-probe SetupHeterodyne Pump-probe Setup
(amplitude) (phase)
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Heterodyne Pump-probe SetupHeterodyne Pump-probe Setup
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Heterodyne Pump-probe SetupHeterodyne Pump-probe Setup
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Heterodyne Pump-probe SetupHeterodyne Pump-probe Setup
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Heterodyne Pump-probe SetupHeterodyne Pump-probe Setup
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Heterodyne Pump-probe SetupHeterodyne Pump-probe Setup
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Heterodyne Pump-probe SetupHeterodyne Pump-probe Setup
(amplitude)
t
reference
pump
Δt
probe
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Michelson Interferometer
Heterodyne Pump-probe SetupHeterodyne Pump-probe Setup
(amplitude)
t
referenceprobe
pump
Δt
(amplitude)
t
reference
pump
Δt
probe reference(amplitude)
t
pump
Δt
probe reference(amplitude)
t
reference
pump
Δt
probe
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Michelson Interferometer
Heterodyne Pump-probe SetupHeterodyne Pump-probe Setup
(amplitude)
t
referenceprobe
pump
Δt
(amplitude)
t
reference
pump
Δt
probe reference(amplitude)
t
pump
Δt
probe reference(amplitude)
t
reference
pump
Δt
probe
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Heterodyne Pump-probe SetupHeterodyne Pump-probe Setup
Michelson Interferometer
1.5 MHz beat
(amplitude) (phase)
(amplitude)
t
reference
pump
Δt
probe
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Ultrafast Gain RecoveryUltrafast Gain Recovery
τgr ≈ 15 ps
τcr ≈ 400 ps
Gain recovery time dictates switching rateGain recovery time dictates switching rate Recovery time is 15 ps for high bias currentsRecovery time is 15 ps for high bias currents
100 GHz switching rate 100 GHz switching rate (faster than possible with electronics)(faster than possible with electronics)
Absoptrion recovery Gain recovery
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Other Ultrafast DynamicsOther Ultrafast Dynamics
Additional ultrafast (~ 1 ps) nonlinear dynamicsAdditional ultrafast (~ 1 ps) nonlinear dynamics
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Other Ultrafast DynamicsOther Ultrafast Dynamics
psSHB 2.0
TPA
ps
eff
25.0
psCH
5.1
ps
CH
5.1
Additional ultrafast (~ 1 ps) nonlinear dynamicsAdditional ultrafast (~ 1 ps) nonlinear dynamics Two-Photon Absorption (TPA)Two-Photon Absorption (TPA) Carrier Heating (CH)Carrier Heating (CH) Spectral Hole Burning (SHB)Spectral Hole Burning (SHB)
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ConclusionsConclusions
First characterization of dynamics of 1.55 First characterization of dynamics of 1.55 µm µm QDQD SOA SOA
Heterodyne pump-probe characterization Heterodyne pump-probe characterization with 150 fs resolutionwith 150 fs resolution
QD SOAs used as nonlinear elements in All-Optical Signal ProcessingQD SOAs used as nonlinear elements in All-Optical Signal Processing
Fast 15 ps gain recoveryFast 15 ps gain recovery promising for ultrafast signal processing to beat electronics limit ( > 40 GHz )promising for ultrafast signal processing to beat electronics limit ( > 40 GHz ) Faster than conventional SOAs (50 – 1000 ps)Faster than conventional SOAs (50 – 1000 ps) Slow absorption dynamics confirms high quantum confinementSlow absorption dynamics confirms high quantum confinement
Ultrafast ~1 ps dynamics due to SHB and CHUltrafast ~1 ps dynamics due to SHB and CH Provides deeper understanding of QD PhysicsProvides deeper understanding of QD Physics
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ReferencesReferences
i. A. J. Zilkie, J. Meier, P. W. E. Smith, M. Mojahedi, J. S. Aitchison, P. J. Poole, C. Nì. Allen, P. Barrios, and D. Poitras, Appl. Phys Lett., in submission
ii. A. J. Zilkie, J. Meier, P. W. E. Smith, M. Mojahedi, J. S. Aitchison, P. J. Poole, C. Nì. Allen, P. Barrios, and D. Poitras, CMJJ5, CLEO 2006
iii. J. Meier, A. J. Zilkie, M. Mojahedi, J. S. Aitchison, R. H. Wang, T. J. Rotter, C. Yang, A. Stintz, K. J. Malloy, CThGG4, CLEO 2006
iv. A. J. Zilkie, J. Meier, P. W. E. Smith, M. Mojahedi, J. S. Aitchison, P. J. Poole, C. Nì. Allen, P. Barrios, and D. Poitras, Photonic Applications in Nonlinear Optics, Nanophotonics, and Microwave Photonics 5971, 59710G (2005). Oral presentation at SPIE Photonics North September 2005
v. B. Leesti, A. J. Zilkie, J. S. Aitchison, M. Mojahedi, R. H. Wang, T. J. Rotter, C. Yang, A. Stintz, and K. J. Malloy (2004) Photonic. Tech. L. 17 (5), 1046-1048 (2005).
vi. B. Leesti, A. J. Zilkie, J. S. Aitchison, M. Mojahedi, P. W. E. Smith, R. H. Wang, T. J. Rotter, C. Yang, A. Stintz, and K. J. Malloy, IEEE LEOS Annual Meeting November 2004, poster presentation by B. Leesti.
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AcknowledgmentsAcknowledgments