Physics and Applications of III-V Materials and Devices
Devices based on III-V materials such as AlGaAs and InGaAsP semiconductor
diode lasers are used in optical communication systems. Many of
the operating characteristics of the devices are not well understood
even though the devices are used extensively in the telecommunications
industry. It is the object of the research programme to study the
physics and applications of III-V materials and devices and to
use the accumulated knowledge and experience to explain the operating
characteristics and to find new applications.
Much of the work uses two technologies that were and are being
developed in the research group: degree of polarization (DOP) of
luminescence and short-external-cavity (SXC) modules. These technologies
enhance the ability of the research group to make contributions.
With the DOP technique, the strain fields owing to, e.g., growth,
processing, metallisation, die bonding, and single dislocations
can be mapped quickly. There are few, if any, research groups that
have this capability. Thus, the effects of strain on device performance
can be determined and means to improve device performance suggested.
The luminescence from quantum wells is highly polarized. We have
shown that the DOP of luminescence from quantum wells is a sensitive
measure of the physical characteristics of the quantum well. Thus
quantum wells can be characterized by the DOP of luminescence and
the information gained by the characterization may be used to understand
aspects of growth and performance of quantum well devices.
With the SXC technology, the spectral output of diode lasers can
be controlled (i.e., the laser can be forced to run single mode
on any of the modes near the gain peak). This allows for investigation
of the wavelength dependence of ,e.g., the modulation bandwidth
of diode lasers, the line width of lasers, and the nonlinear gain
parameter. SXC lasers can also be used to construct sensors and
to perform spectroscopy. The sensor work typically involves development
of a system including source, optics, modulation/demodulation scheme,
detection, signal processing electronics and algorithm, as necessary
and application of the system to a relevant problem. We use a custom
designed diffractive optical element as the feedback element for
the external cavity lasers. The spectral properties of devices
has been a continuing interest and recently has led to work on
gain-coupled DFB lasers.
We design, fabricate, characterize and use lasers with broad gain
peaks for operation over extended spectral intervals. The work
on design, fabrication, and understanding of broad gain peak lasers
is interesting for the physics of operation that is obtained and
for the development of sources.
D.T. Cassidy, S.K.K. Lam, B.Lakshmi, and D.M. Bruce, " Strain
mapping by measurement of the degree of polarization of photoluminescence",
Appl. Opt., submitted June 2003 for publication.
M.A. Fritz and D.T. Cassidy, "Diode laser bonding",
IEEE Trans. on Components and Packaging Technology, accepted June
2003 for publication.
S.K.K. Lam, R.E. Mallard, and D.T. Cassidy, "Analytical model
for saturable aging in semiconductor lasers", J. Appl. Phys.,
to be published in August 2003.
G.B. Morrison and D.T. Cassidy, "A probability-amplitude
transfer-matrix method for calculating the distribution of light
in semiconductor lasers", IEEE J. Quantum Electron. 39, 431-437
S.C. Woodworth, D.T. Cassidy, and M.J. Hamp, "Experimental
analysis of a broadly tunable InGaAsP laser with compositionally
varied quantum wells", IEEE J. Quantum Electron. 39, 426-430
G.B. Morrison and D.T. Cassidy, "A model for the above threshold
spectra of truncated well distributed feedback lasers", IEEE
J. Quantum Electron. 39, 426-430 (2003).
D.T. Cassidy, "Spatially-resolved and polarization-resolved
photoluminescence for study of dislocations and strain in III-V
materials", Mater. Sci. Eng. B91-92, 2-9 (2002).
S.C. Woodworth, D.T. Cassidy, and M.J. Hamp, "Sensitive absorption
spectroscopy by use of an asymmetric multiple-quantum-well diode
laser in an external cavity", Appl. Opt. 40, 6719-6724 (2001).
G.B. Morrison, D.T. Cassidy, and D.M. Bruce, "Facet phases
and sub-threshold spectra of DFB lasers: spectral extraction, features,
explanations, and verification", IEEE J. Quantum Electron.
37, 762-769 (2001).
D. Lisak, D.T. Cassidy, and A.H. Moore, "Bonding stress and
reliability of high power GaAs-based lasers", IEEE Trans.
on Components and Packaging Technology, submitted March 2000.
M.J. Hamp and D.T. Cassidy, "Critical design parameters for
engineering broadly tunable asymmetric multiple quantum well lasers",
IEEE J. Quantum Electron., to be published in August 2000.
G.B. Morrison and D.T. Cassidy, "Improving the ability of
a distributed feedback laser transfer-matrix model to fit spectra
from distributed feedback lasers", IEEE Photon. Technol. Lett.,
to be published in July 2000.
G.B. Morrison and D.T. Cassidy, "A probability-amplitude
transfer matrix model for distributed feedback laser structures",
IEEE J. Quantum Electron. 36, 633-640 (2000).
M.J. Hamp, D.T. Cassidy, B.J. Robinson, Q.C. Zhao, and D.A. Thompson, "Effect
of barrier thickness of the carrier distribution in asymmetric
multiple quantum well InGaAsP lasers", IEEE Photon. Technol.
Lett. 12, 134-136 (2000).
G.B. Morrison, D.M. Adams, and D.T. Cassidy, "Extraction
of gain parameters for truncated well gain-coupled DFB lasers",
IEEE Photon. Technol. Lett. 11, 1566-1568 (1999).
D.T. Cassidy and M.J. Hamp, "Diffractive optical element
used in an external feedback configuration to tune the wavelength
of uncoated Fabry-Pérot diode lasers", J. Mod. Opt.
46, 1071-1078 (1999).
M.J. Hamp, D.T. Cassidy, B.J. Robinson, Q.C. Zhao, and D.A. Thompson, "Nonuniform
carrier distribution in asymmetric multiple-quantum-well InGaAsP
laser structures with different number of quantum wells",
Appl. Phys. Lett. 74, 744-746 (1999).
B. Lakshmi, D.T. Cassidy, and B.J. Robinson, , "Anisotropic
interfacial strain in InP/InGaAs/InP quantum wells", J. Appl.
Phys. 84, 5739-5742 (1998).
M.J. Hamp, D.T. Cassidy, B.J. Robinson, Q.C. Zhao, D.A. Thompson,
and M. Davies, "Effect of barrier height on the uneven carrier
distribution in asymmetric multiple-quantum-
well InGaAsP lasers", IEEE Photon. Technol. Lett. 10, 1380-1382
A. Gupta, G.C. Weatherly, D.T. Cassidy, and D.M. Bruce, "Characterization
and modelling of the strain fields associated with InGaAs layers
on V-grooved InP substrates", J. Appl. Phys. 82, 6016-6023
X. Zhu, D.T. Cassidy, M.J. Hamp, D.A. Thompson, B.J. Robinson,
Q.C. Zhao, and M. Davies, "1.4µm InGaAsP-InP Strained
Multiple-Quantum-Well Laser for Broad-Wavelength Tunability",
IEEE Photon. Technol. Letters. 9, 1202-1204 (1997).
X. Zhu and D.T. Cassidy, "Modulation spectroscopy with a
semiconductor diode laser by injection-current modulation",
J. Opt. Soc. Am. B., 14, 1945-1950 (1997).
D.M. Adams, D.T. Cassidy and D.M. Bruce, "Scanning photoluminescence
technique to determine the phase of the grating at the facets of
gain-coupled DFB's", IEEE J. Quantum Electron. 32, 1237-1242
X. Zhu and D.T. Cassidy, "Liquid detection using InGaAsP
semiconductor lasers with multiple short-external cavities",
Appl. Opt. 35, 4689-4693 (1996).
B. Lakshmi, D.T. Cassidy and B.J. Robinson, "Quantum well
strain and thickness characterization by degree of polarization",
J. Appl. Phys. 79, 7640-7645 (1996).
A. Nguyen and D.T. Cassidy, "Flexure-mounted external cavity
for single mode operation of semiconductor diode lasers",
Rev. Sci. Instrumen. 66, 4458-4460 (1995).
J. Yang and D.T. Cassidy, "Strain measurement and estimation
of photoelastic effects and strain-induced optical gain change
in ridge waveguide lasers", J. Appl. Phys. 77, 3382-3387 (1995).
J.E. Hayward and D.T. Cassidy, "Nonlinear gain and the spectral
output of short-external-cavity 1.3 µm InGaAsP semiconductor
diode lasers", IEEE J. Quantum Electron. 30, 2043-2050 (1994).