Ultrafast Nonlinear Dynamics of Quantum Dot Semiconductor Optical

Ultrafast Nonlinear Dynamics of Quantum Dot Semiconductor Optical Amplifiers Aaron J. Zilkie Ph. D Candidate Supervisors: Peter W. E. Smith J. Stewart Aitchison Connections 2006 In collaboration with: National Research Council of Canada, Ottawa, ON Slide

Outline 1) Introduction and Motivation 2) Experimental Setup n Heterodyne pump-probe lab setup 3) Ultrafast Dynamics n Ultrafast Gain recovery n Additional Ultrafast Nonlinearities 4) Conclusions Friday, June 9 U of T Connections 2006 3

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 Friday, June 9 U of T Connections 2006 4

Motivation All Optical Signal Processing SOA used as nonlinear switching element n Supression Nonlinear phase change balanced 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 Friday, June 9 U of T Connections 2006 5

Heterodyne Pump -probe Lab Setup Slide

Heterodyne Pump-probe Setup (amplitude) Friday, June 9 U of T Connections 2006 (phase) 7

Heterodyne Pump-probe Setup Friday, June 9 U of T Connections 2006 8

Heterodyne Pump-probe Setup Friday, June 9 U of T Connections 2006 9

Heterodyne Pump-probe Setup Friday, June 9 U of T Connections 2006 10

Heterodyne Pump-probe Setup Friday, June 9 U of T Connections 2006 11

Heterodyne Pump-probe Setup Friday, June 9 U of T Connections 2006 12

Heterodyne Pump-probe Setup pump probe reference (amplitude) Δt t Friday, June 9 U of T Connections 2006 13

Heterodyne Pump-probe Setup Michelson Interferometer pump probe reference (amplitude) Δt Δt t Friday, June 9 U of T Connections 2006 14

Heterodyne Pump-probe Setup Michelson Interferometer pump probe reference (amplitude) Δt Δt t Friday, June 9 U of T Connections 2006 15

Heterodyne Pump-probe Setup Michelson Interferometer pump probe reference (amplitude) Δt t 1. 5 MHz beat (amplitude) Friday, June 9 U of T Connections 2006 (phase) 16

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) Friday, June 9 U of T Connections 2006 17

Other Ultrafast Dynamics Additional ultrafast (~ 1 ps) nonlinear dynamics Friday, June 9 U of T Connections 2006 18

Other Ultrafast Dynamics TPA Additional ultrafast (~ 1 ps) nonlinear dynamics n n n Friday, June 9 Two-Photon Absorption (TPA) Carrier Heating (CH) Spectral Hole Burning (SHB) U of T Connections 2006 19

Conclusions First characterization of dynamics of 1. 55 µm QD SOA Heterodyne pump-probe characterization with 150 fs resolution n 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 n n n Ultrafast ~1 ps dynamics due to SHB and CH n Friday, June 9 Provides deeper understanding of QD Physics U of T Connections 2006 20

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, CMJJ 5, 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, CTh. GG 4, 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, 59710 G (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. Friday, June 9 U of T Connections 2006 21

Acknowledgments Friday, June 9 U of T Connections 2006 22