InAs Quantum Dot-Based Devices for Ultrafast Photonic Signal Processing

SOLID STATE ELECTRONICS LABORATORY
SEMINAR ANNOUNCEMENT

O. Wada, T. Inoue and C. Jin
Department of Electrical and Electronics Engineering
Graduate School of Engineering, Kobe University, Kobe, Japan

Friday, January 29, 2010
2:00-3:00 P.M.
Room 1005 EECS

InAs Quantum Dot-Based Devices for Ultrafast Photonic Signal Processing

Abstract
This presentation discusses first the quantum dot (QD) growth technique based on molecular beam epitaxy (MBE), and then describes their application to photonic devices for ultrafast telecommunications such as SOAs and all-optical switches. An important issue in QD-SOAs is the polarization sensitivity which is primarily caused by the flattened shape of QDs. We have introduced a unique approach of columnar dot technique in which a number of QD layers are closely stacked to form a better geometrical isotropy. By optimizing the geometry and strain in InAs/InGaAs/InP QD system, polarization-insensitive SOA performance has been demonstrated for the first time at 1.55 μm. We also propose an alternative approach of using remotely stacked QD layers and demonstrate basic polarization-insensitive characteristics. As for all-optical switches, recent result of vertical structure QD-based all-optical switches is described. This switching device has a vertical cavity composed of a pair of asymmetric distributed Bragg reflectors (DBRs) incorporating a QD nonlinear medium. Through optimizing the design and fabrication of vertical structure all-optical devices, optical reflection-type switch response with a time constant as fast as 23 ps has been demonstrated. We thus illustrate the unique prospects of QD-based devices to future photonic communication and signal processing systems.

Professor Osamu Wada received his M.Sc and Ph.D degree from Kobe University, Japan and the University of Sheffield, United Kingdom, respectively. From 1971-1996, he was at Fujitsu Research Laboratories, where he did pioneering research and development of integrated transmitters and photoreceivers for fiber-optic communication. From 1996-2001 Professor Wada was at the Femtosecond Technology Research Association Institute in Tsukuba, where he did groundbreaking work on quantum well and quantum dot based all-optical switching devices He has been at Kobe University since 2001, where his group is conducting research on the characterization of quantum dots and their application in ultrafast optical devices for signal processing.

Professor Osamu Wada received his M.Sc and Ph.D degree from Kobe University, Japan and the University of Sheffield, United Kingdom, respectively. From 1971-1996, he was at Fujitsu Research Laboratories, where he did pioneering research and development of integrated transmitters and photoreceivers for fiber-optic communication. From 1996-2001 Professor Wada was at the Femtosecond Technology Research Association Institute in Tsukuba, where he did groundbreaking work on quantum well and quantum dot based all-optical switching devices He has been at Kobe University since 2001, where his group is conducting research on the characterization of quantum dots and their application in ultrafast optical devices for signal processing.