ECE Distinguished Lecture with Professor Larry Coldren

4:00 pm on Wednesday, November 20, 2013
Photonics Center, 8 Saint Mary’s St., Room 211
Photonic Integrated Circuits as Key Enablers for Coherent Sensor and Communication Systems

With Professor Larry A. Coldren
Electrical & Computer Engineering and Materials Departments
University of California, Santa Barbara

Refreshments will be served outside Room 339 at 3:45 p.m.

Faculty Host: Jonathan Klamkin

Abstract: After many years in the research lab, photonic integrated circuits (PICs) are emerging into practical commercial products with advantages not only in size, weight and power (SWaP), but also in cost and performance. This presentation will review some recent advances in semiconductor-based devices to which the author’s group has contributed.

The first area is PICs for optical fiber communications. Recently, wavelength division multiplexing (WDM) has begun to reach practical limits. Thus, advanced modulation formats, acting on both the amplitude and phase of the optical field, as well as coherent receivers that recover the full vector field have been employed to further improve spectral efficiency. Widely-tunable advanced transmitter PICs and coherent receiver PICs have been demonstrated with desirable SWaP characteristics. Coherent receivers incorporating ultra-stable, high-bandwidth optical-phase-locked-loops (OPLLs) have also been demonstrated.

The second area is sensor PICs. One example is a high-speed two-dimensional optical beam sweeper. An on-chip, widely-tunable laser sweeps the beam in one direction via surface-grating emission; steering in the orthogonal direction is accomplished by controlling a 1-D waveguide array. Thus, only n+1 control elements are needed for n2 resolution points.

About the Speaker: Larry A. Coldren is the Fred Kavli Professor of Optoelectronics and Sensors at the University of California, Santa Barbara, Calif.. He received the Ph.D. degree in Electrical Engineering from Stanford University in 1972. After 13 years in the research area at Bell Laboratories, he joined UC-Santa Barbara in 1984, where he now holds appointments in Materials and Electrical & Computer Engineering and is Director of the Optoelectronics Technology Center. In 1990, he co-founded Optical Concepts, later acquired as Gore Photonics, to develop novel VCSEL technology, and in 1998, he co-founded Agility Communications, later acquired by JDSU, to develop widely-tunable integrated transmitters.

At Bell Labs, Coldren initially worked on waveguided surface-acoustic-wave signal processing devices and coupled-resonator filters. He later developed tunable coupled-cavity lasers using novel reactive-ion etching (RIE) technology that he created for the then new InP-based materials. At UCSB he continued work on multiple-section tunable lasers, in 1988 inventing the widely-tunable multi-element mirror concept, which is now used in some JDSU products. During the late eighties he also developed efficient vertical-cavity multiple-quantum-well modulators, which led to novel vertical-cavity surface-emitting laser (VCSEL) designs that provided unparalleled levels of performance. Professor Coldren continues to be active in developing new photonic integrated circuit (PIC) and VCSEL technology, including the underlying materials growth and fabrication techniques. In recent years, for example, he has been involved in the creation of efficient all-epitaxial InP-based and high-modulation speed GaAs-based VCSELs as well as a variety of InP-based PICs incorporating numerous optical elements for widely-tunable integrated transmitters, receivers, and wavelength converters operating up to 40 Gb/s.

Professor Coldren has authored or co-authored over 1000 journal and conference papers, seven book chapters, and one textbook, and has 65 patents. He has presented dozens of invited and plenary talks at major conferences, he is a Fellow of the IEEE, OSA, and IEE, the recipient of the 2004 John Tyndall and 2009 Aron Kressel Awards, and a member of the National Academy of Engineering.