University Oral Examination - Seth Bank (November 1, 2005 1:30PM)

Seth Bank sbank at
Sun Oct 23 11:43:25 PDT 2005

Special University Oral Examination
Seth R. Bank
Department of Electrical Engineering
Stanford University

Tuesday, November 1, 2005
1:30 PM (Refreshments served at 1:15 PM)
Center for Integrated Systems Extension (CISX) Auditorium (Rm. 101X)

"High-Performance 1.55-um GaAs-Based Lasers"

Next-generation local and metro-area optical networks require 
high-performance lasers, detectors, and modulators operating at ~1.55 um. 
In contrast to long-haul networks, components must be very inexpensive, 
power efficient, and producible in high volumes - all with little sacrifice 
to performance. Two classes of lasers are required. The first is low-power 
(~1-10 mW) 1.55 um communication sources, such as vertical-cavity 
surface-emitting lasers (VCSELs), that must be insensitive to ambient 
temperature and operable at high modulation rates. The second class is 
higher output power (>300 mW) lasers emitting at shorter wavelengths (~1.48 
um) for pumping Raman and doped fiber amplifiers.

This seminar describes the development of a novel GaAs-based gain material, 
GaInNAs(Sb), that is ideal for both applications. Material growth is 
challenging, but optical quality can be improved dramatically through the 
introduction of antimony and other growth enhancements that will be 
discussed. We demonstrate the first low-threshold GaAs-based lasers from 
1.45-1.55 um. Laser threshold current densities are as low as 440 A/cm^2 -- 
comparable, if not superior, to commercially available InP-based devices. 
High continuous-wave output powers >400 mW, more than sufficient for 
amplifier applications, are achieved from even simple single quantum well 
structures. Laser results at 1.55 um validate this new materials system for 
use in VCSEL sources as well. Studies of the temperature stability of these 
devices will also be presented.

Seth Bank                       sbank at
Doctoral Candidate              Ph:  650-725-8313
James S. Harris Group           Fax: 650-723-4659
Electrical Engineering
Stanford University

CIS-X Rm. 126X
Via Ortega
Stanford, CA 94305-4075
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