Quantum-Dot Lasers and Amplifiers by yurtgc548

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									 Ultrafast Nonlinear Dynamics of
           Quantum Dot
Semiconductor Optical Amplifiers

           Aaron J. Zilkie
            PhD Candidate
                                      Supervisors:
                                    Peter W. E. Smith
                                   J. Stewart Aitchison




                                 In collaboration with:
                               National Research Council
                                of Canada, Ottawa, ON
            Connections 2006
                                          Outline
          1) Introduction and Motivation
          2) Experimental Setup
                    Heterodyne pump-probe lab setup

          3) Ultrafast Dynamics
                    Ultrafast Gain recovery
                    Additional Ultrafast Nonlinearities

          4) Conclusions
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                                 Introduction
   Quantum Dot Semiconductor Optical Amplifiers (QD SOA)
                                            +
                                                                    SEM Cross-section
                                                   p


                                               n


                                                                          500 nm
                                           -


        “Single pass laser” – light enters, experiences gain via stimulated
        emission as it passes through
        QD SOAs predicted to have 10-100 X faster recovery times than others
        NRC QDs Novel: First to work at 1.55 μm telecom wavelengths
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                                          Motivation
                              All Optical Signal Processing

                                                                  Nonlinear phase change




                                                                  Supression
                                                                               balanced                balanced



        SOA used as nonlinear switching element                                           unbalanced
                Control pulses induce phase change
                     light can switch light!
        SOA ultrafast dynamics critically influence switching window
        Our Work: Measure the ultrafast dynamics of novel QD SOAs
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Heterodyne
Pump-probe
 Lab Setup
                 Heterodyne Pump-probe Setup




                                                   (amplitude)   (phase)



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                 Heterodyne Pump-probe Setup




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                 Heterodyne Pump-probe Setup




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                 Heterodyne Pump-probe Setup




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                 Heterodyne Pump-probe Setup




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                 Heterodyne Pump-probe Setup




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                 Heterodyne Pump-probe Setup

                              pump
                 probe            reference
                              (amplitude)
                         Δt

                                         t




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                 Heterodyne Pump-probe Setup
                                                          Michelson Interferometer
                          pump pump
                       pump pump
                        probe             reference
                                    (amplitude)
                             Δt
                         Δt Δt Δt

                                                      t




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                 Heterodyne Pump-probe Setup
                                                          Michelson Interferometer
                          pump pump
                       pump pump
                        probe             reference
                                    (amplitude)
                             Δt
                         Δt Δt Δt

                                                      t




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                 Heterodyne Pump-probe Setup
                                                           Michelson Interferometer
                                     pump
                        probe            reference
                                     (amplitude)
                                Δt

                                                     t
                                                                         1.5 MHz
                                                                         beat




                                                         (amplitude)   (phase)



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                      Ultrafast Gain Recovery

                    Absoptrion recovery                     Gain recovery


                            τcr ≈ 400 ps

                                                                τgr ≈ 15 ps




        Gain recovery time dictates switching rate
        Recovery time is 15 ps for high bias currents
                  100 GHz switching rate
         (faster than possible with electronics)
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                     Other Ultrafast Dynamics




        Additional ultrafast (~ 1 ps) nonlinear dynamics




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                           Other Ultrafast Dynamics

                          SHB  0.2 ps

        eff 
        0.25 ps
                                                                     CH 
                                                                    1.5 ps
        TPA
                           CH 
                          1.5 ps



        Additional ultrafast (~ 1 ps) nonlinear dynamics
                    Two-Photon Absorption (TPA)
                    Carrier Heating (CH)
                    Spectral Hole Burning (SHB)
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                                       Conclusions
                 First characterization of dynamics of 1.55 µm QD SOA
                 Heterodyne pump-probe characterization with 150 fs resolution

             QD SOAs used as nonlinear elements in All-Optical Signal Processing

             Fast 15 ps gain recovery
                 promising for ultrafast signal processing to beat electronics limit ( > 40 GHz )
                 Faster than conventional SOAs (50 – 1000 ps)
                 Slow absorption dynamics confirms high quantum confinement

             Ultrafast ~1 ps dynamics due to SHB and CH
                 Provides deeper understanding of QD Physics




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                                                 References
    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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                 Acknowledgments




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