Ultrafast Nonlinear Dynamics of Quantum Dot Semiconductor Optical Amplifiers

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

33Friday, June 9 U of T Connections 2006Friday, June 9 U of T Connections 2006

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


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


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


Heterodyne Pump-probe SetupHeterodyne Pump-probe Setup

(amplitude) (phase)



(amplitude)

t

reference

pump

Δt

probe


Michelson Interferometer


(amplitude)

t

referenceprobe

pump

Δt

(amplitude)

t

reference

pump

Δt

probe reference(amplitude)

t

pump

Δt


t

reference

pump

Δt

probe




(amplitude)

t

referenceprobe

pump

Δt

(amplitude)

t

reference

pump

Δt


t

pump

Δt


t

reference

pump

Δt

probe




1.5 MHz beat

(amplitude) (phase)

(amplitude)

t

reference

pump

Δt

probe


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


Other Ultrafast DynamicsOther Ultrafast Dynamics

Additional ultrafast (~ 1 ps) nonlinear dynamicsAdditional ultrafast (~ 1 ps) nonlinear dynamics


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)


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


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.


AcknowledgmentsAcknowledgments

Ultrafast Nonlinear Dynamics of Quantum Dot Semiconductor Optical Amplifiers

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