988
IEEE JOURNAL ON SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 6, NO. 6, NOVEMBER/DECEMBER 2000
Monolithic Tunable Diode Lasers
Larry A. Coldren, Fellow, IEEE
Invited Paper
Abstract—After over two decades of exploration, tunable diode
lasers are beginning to find significant applications, driven largely
by the huge demand for bandwidth that is guiding many developments in the optical fiber communication business today. In this
paper, some of the history and key developments that have led to
the technologies available today will be reviewed from the perspective of the author. After discussion of some of the early work, the
focus will shift to widely tunable diode lasers, which would appear to be key enablers for future dense wavelength-division multiplexing and optical switching and networking systems. The distinguishing characteristics of the current technological alternatives
will be summarized.
Index Terms—Optical networking circuits, photonic integrated
circuits, semiconductor lasers, tunable lasers, WDM.
I. INTRODUCTION
W
HETHER due to pent-up demand for bandwidth or stock
market profits looking for a new killer technology to remultiply prior advances, the fact is, people really seem to be
interested in tunable diode lasers—finally. Please understand
that the “finally” comes from some 20 years of preaching the
gospel of tunable lasers to largely nonbelievers of this perpetual
“technology of the future.” I guess the future has finally arrived—maybe just in time for some of us diehards looking for
some technological event to mark the coming of the new millennium.
Of course, technology generally does not generate profits on
its own—applications do. (Unless of course, you sell your company for a billion or two before making anything real.) So, what
are the killer applications that are driving the demand for tunable lasers? Source sparing or distributed-feedback (DFB) replacement in wavelength-division multiplexed (WDM) systems
is one answer that is commonly heard. The tunable laser could
be set to any desired wavelength either in the factory or in the
field by a software command, and this would eliminate the need
to keep a hundred or so specific wavelength DFBs. The only
catch is that the tunable laser has to do everything as well as
a DFB—power, spurious mode suppression, wavelength stability, lifetime, etc.—but just be tunable over, say 40 nm. Oh
yes, maybe one could charge a premium of 20% or so for this
luxury. Quite a tall order! But, although the challenge is great,
Manuscript received June 8, 2000. The work at UCSB was supported by NRL
and DARPA.
The author is with the ECE Department, University of California, Santa Barbara, CA 93106 USA and Agility Communications, Santa Barbara, CA 93117
USA.
Publisher Item Identifier S 1077-260X(00)11615-6.
the market is nearly infinite—one could basically replace most
DFB lasers with such a single product overnight. Now, while the
businessman in me worries about meeting such demand, the researcher in me is thoroughly bored. Surely, we did not spend 20
years developing sophisticated wavelength agile sources just to
replace single-frequency DFBs! Well, maybe—or maybe there
are even bigger and more exciting applications.
Optical switching, routing, and networking using such wavelength-agile sources may be the real “killer-aps.” In these cases
there may be more leverage and less competition as compared
to a replacement technology. Optical switching will be very important over the next decade as optical networks become more
connected. Tunable lasers in all-optical switching are intriguing
because in many important cases most of the switching is wavelength switching. That is, nodes with on the order of a thousand different optical channels to be switched generally have
final inputs and outputs that consist of only a dozen or so fibers,
but with a hundred or so different wavelengths on each. Thus,
format-independent wavelength switches or wavelength converters may be as important as pure space switches, particularly
if they incorporate widely tunable lasers capable of outputting
more than a hundred wavelength channels. (A 40-nm band contains about 100 wavelength channels spaced on the 50-GHz ITU
grid.)
In fact, I believe that such wavelength-agile wavelength converters will probably be combined with modest dimension space
switches in many architectures. However, it is also important
to realize that the combination of such wavelength converters
with passive wavelength routers (e.g., spectrometer-like elements such as AWGs) will provide large format-independent
space switches without any other technology. Finally, WDM
Add/Drop ports would become vastly more interesting if
both input filters (Drops) and output sources (Adds) were
wavelength tunable. Thus, tunable lasers will probably find
significant usage in these applications as well.
Beyond optical switching or Add/Drop functions at some location is optical routing and networking that involves some sort
of architecture using wavelength to address and direct information between desired locations. Relatively simple passive filters
can be used in combination with wavelength encoding to perform higher level networking functions. Obviously, simple, integrable, widely tunable lasers are key enablers for these architectures.
In this paper, I intend to focus on the development of monolithic tunable diode lasers over the past 25 years or so. These developments have been greatly fostered by IEEE/LEOS, whose
1077–260X/00$10.00 © 2000 IEEE
COLDREN: MONOLITHIC TUNABLE DIODE LASERS
lifetime has nearly matched that of such lasers. I suspect that
most of the publications, conference talks, and workshops promoting the development of tunable diode lasers have been at
least cosponsored by LEOS. Thus, the inclusion of this paper in
this millennium issue of the JSTQE is particularly appropriate.
The coverage of the early work will be relatively superficial—a result of hindsight which now allows us to only focus on
those things that have survived the test of time. Thus, much of
the exciting work, which may indeed have stimulated the more
relevant events, will not get its just credit. The focus will also
be directed more toward the widely tunable monolithic lasers of
today. Thus, while modestly tunable structures that preceded the
more widely tunable embodiments still remain in strong commercial contention for future wavelength-agile systems, they
will be viewed mainly as stepping stones toward these newer,
more capable embodiments.
989
(a)
II. BEGINNINGS
Much of the earliest work that underlies many embodiments
of today’s monolithic tunable diode lasers was carried out in
Prof. Suematsu’s group at the Tokyo Institute of Technology.
He clearly led the most significant effort to develop distributedBragg-reflector (DBR) lasers that incorporated separate active
and passive grating reflector regions [1], [2] and later tunability
[3], [4] in the early 1980s. Fig. 1 illustrates some of these initial
tunable DBR results. Some earlier work in the 1970s included
vertically integrated twin guide structures to separate active and
passive DBR functions [5], but they always had inherent limitations, mainly with the twin-guide active/passive interfaces.
Of course, this fell on the heels of efforts on distributed-feedback (DFB) lasers, which have no active/passive interfaces, but
I think it is fair to say that these were never intended or appropriate for wide tunability. In fact, it is even probably fair to
say that the early DBR work was not aimed at obtaining tunable sources, but rather ones which could be integrated with
passive waveguides for monolithic coupling to other integrated
optical components. The primary challenge was to get this integration with good “dynamic single mode” performance, i.e.,
single-mode outputs even under large-signal modulation.
The first concerted efforts to make monolithic tunable diode
lasers to my knowledge were carried out in my lab at Bell Labs
in the early 1980s, but this did not involve DBRs. Instead we
incorporated an all-active two-section Fabry–Perot design with
an intermediate etched groove to provide an active–active coupled-cavity tunable structure [6]–[10]. Fig. 2 shows some early
tuning results under high-speed pulsed modulation. The earliest
demonstrations in 1981 had poorer sidemode suppression ratio
(SMSR), but with reasonable tuning performance. This coupled-cavity structure was later popularized in a cleaved-coupled-cavity embodiment [11], [12], which, of course, was not
monolithic, but due to the use of more mature materials and ideal
facets, it allowed for more detailed work on the coupled-cavity
approach. For example, the first control circuits to lock a single
mode condition were demonstrated [13], and chirp-free modulation was shown to be possible by splitting the modulation
current to the two sections [14], [15]. The control work also included the first use of the gain voltage to provide an integrated
(b)
Fig. 1. Early DBR laser results on GaInAsP–InP BH-BJB-DBR: (a)
schematic and (b) tuning results [3]. Spurious mode suppression ratio was
small. [Reprinted with permission from Electronics Letters, vol. 19, no. 17 pp.
656–657, 1983.]
internal monitor for feedback to the single-mode locking circuit
[16]. The monolithic etched-groove approach also eventually
showed ideal single-mode and tuning performance, once advanced buried-heterostructure base structures and high-quality
groove formation techniques were incorporated [17], [18].
Work on two- and three-section tunable DBR lasers became
the more or less accepted venue in the mid 1980s, and this is
the tunable laser of choice for many even to this day. Numerous
efforts in Japan [4], [19]–[25], Europe [26], [27] and the United
States [28], [29] provided demonstrations of high-quality tunable lasers with tuning ranges 5–10 nm. Recipes to obtain
990
IEEE JOURNAL ON SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 6, NO. 6, NOVEMBER/DECEMBER 2000
(a)
(a)
(b)
Fig. 2. (a) Etched-groove coupled-cavity laser and (b) pulsed results (1-ns
gating pulse length on section #2) [8]. Tuning was discontinuous. [Reprinted
with permission from Electronics Letters, vol. 18, no. 21 pp. 901–902 1982.]
truly single-mode continuous tuning in three section devices by
applying the appropriate relative currents to the passive sections
were also presented [30] and demonstrated [23]. Fig. 3 gives
schematics of two- and three-section DBRs along with example
results from this period [21], [28]. These results are still representative of what can be expected from these structures, although there has been a lot of progress in reproducibility, reliability, and efficiency in the last decade [31]–[33].
Other efforts during the late 1980s included work on multiple-section DFB [34]–[38] and twin-guide structures [39],
[40]. This work also continued into the early 1990s by the
initial investigators [41], [42] as well as numerous others [43],
but its importance seems to have faded in recent years. So, with
some apologies to those who still believe in such approaches, I
have chosen to focus more on the events leading up to the more
popular versions of today—especially those which can provide
wide tuning ranges.
III. RECENT DEVELOPMENTS: WIDELY TUNABLE DIODE
LASERS
Including work of the past decade in “recent developments”
may well be a comment on the time I’ve spent in this field. How-
(b)
Fig. 3. (a) Two- and (b) three-section DBRs and results from the late 1980s
[21], [28]. Tuning current applied to Bragg mirror. [Reprinted with permission
from Tunable Laser Diodes, Fig. 5.2 (Artech, London: 1998)—schematics and
Applied Physics Letters vol. 52, pp. 1285–1287—two-section and vol. 53, pp.
1036–1038—three-section 1988.]
ever, my purpose in dividing the work here is mostly because
I believe there was a bit of a paradigm shift during the first
half of the past decade. This was in part due to the recession
that disrupted many company’s plans, and slowed the introduction of new optical communications systems. In the United
States the level of government funding for research was drastically reduced as military spending was cut back; the United
States and Europe were also lagging far behind Japan in producing optoelectronic components and systems. Thus, there was
a significant effort to better couple research efforts at universities to companies, and to organize United States and European optoelectronic industries into joint efforts to develop new
optoelectronic technology. New government-sponsored projects
COLDREN: MONOLITHIC TUNABLE DIODE LASERS
991
were now more directed at commercial applications, and this
also tended to focus on longer term goals than typical for industry R&D. Optoelectronic industry development associations
were formed. New optical communication architectures such as
the use of WDM to increase bandwidth were fostered. This led
to the demand for new and different componentry. Component
ideas that had been germinated but not well cultivated, such
as vertical-cavity surface-emitting lasers (VCSELs), and widely
tunable lasers, gained more support and interest. Of course, in
the latter half of the decade a prospering economy in the United
States as well as the discovery of the internet by the common
man, accelerated the demand for bandwidth. So, the roadmaps
and timelines that suggested the need for WDM and optical networking approaches were greatly accelerated. So, here we are,
with more demand for optical gadgets having more capability
than ever before. Isn’t it wonderful?
Now coming back to the subject, the early part of the 1990s
was marked by the development of a number of novel widely
tunable laser sources. These include configurations employing
two multielement mirrors and vernier-effect tuning enhancement [44]–[51] structures using grating-assisted codirectional
couplers for enhanced tuning [52]–[56], some Y-branch configurations [57]–[59], and a little later, VCSELs with movable micromechanical mirrors [60]–[63]. Another approach is the use
of arrays, which can combine several modestly tunable lasers to
obtain a wide overall tuning range [64]–[69]. They are still of
great interest today, but not within the scope of this paper.
Fig. 4 shows the sampled-grating DBR (SGDBR) laser,
which was the first monolithic device to ever tune over a wavelength range of 30 nm or more [47]. The originally proposed
four section design and vernier mirror tuning concept [45],
along with some early discontinuous tuning results that used
only three sections [48] are illustrated. The first demonstrations
actually used an all-active two-section design [46], [47], which
had somewhat less tuning (30 nm) and SMSR. As illustrated
in Fig. 4, the sampled-grating design uses two different multielement mirrors to create two reflection combs with different
wavelength spacings [44].
The laser operates at a wavelength where a reflection peak
from each mirror coincide. Since the peak spacings are different,
only one pair of peaks can line up at a time. The peaks are spaced
by
(1)
is the grating sampling period and
is the group
where
index of refraction. This is typically chosen to be a little less than
the available direct index tuning range, i.e., about 6–8 nm so that
the range between peaks can be accessed by tuning both mirrors together. Now for vernier tuning enhancement, one mirror
is tuned relative to the other. Since the difference in peak spac, is much less than the peak
ings between the two mirrors,
, only a small differential tuning is
spacing of either mirror,
required to line up adjacent reflection peaks—say about 1 nm,
for example. Thus, we observe a tuning enhancement of
(2)
and for the typical values considered, this is equal to about
six-to-eight. This process of equal and differential mirror tuning
can clearly be used to cover the full desired tuning range, which
is typically 40–80 nm, depending upon the specifics of the design. As shown in Fig. 4(a), a fourth-phase section is also included to fine tune the mode location to access exact wavelength
values.
The SMSR tends to be quite large for these devices, because
of the relatively narrow mirror reflection peaks, which have a
full width at half maximum of about
(3)
and this is typically designed to be about three-to-four mode
, where
spacings,
(4)
is the penetration depth to the effective mirror plane
and
(typically 0.3–0.5 the total sampled-grating length, depending
is the net effective cavity
upon reflection magnitude), and
length measured between effective SGDBR mirror planes.
Fig. 5 gives more recent SGDBR laser results. In this case a
buried-ridge stripe (BRS) laser design is employed [70], [71].
This provides for more efficient injection and confinement of
carriers in the mirror regions. In addition, improved MOCVD
techniques increased the carrier lifetime in the mirrors [72].
Similar lasers have been provided by GEC–Marconi–Caswell
[73] for the European Race project.
One significant feature of the common-waveguide design of
the SGDBR is that other optical elements can be easily integrated using the same fabrication sequence. This is particularly
simple with the SGDBR, since active, passive, and grating sections are already selectively defined in the standard laser fabrication process, and with these elements, integrated amplifiers
[71], modulators [70], filters, and amplitude or wavelength monitors [74] can be defined. Fig. 6 gives some recent examples.
Note that all of these results were obtained without adding additional regrowths or processing steps relative to those required
for the SGDBR laser.
Most of the features of the SGDBR are shared by the superstructure-grating DBR (SSGDBR) design shown in Fig. 7.
In this case, the desired multiple-peaked reflection spectrum
of each mirror is created by using a phase modulation of the
grating rather than an amplitude modulation function as in the
SGDBR. Periodic bursts of a grating with a chirped period are
typically used. This multielement mirror structure requires a
smaller grating depth and can provide an arbitrary mirror peak
amplitude distribution if the grating chirping is controlled [75],
[76]. However, the formation of this grating is very complex,
typically requiring direct e-beam exposure. Also, because the
grating exists everywhere throughout the mirror, the carrier lifetimes in the mirror regions tend to be lower than with the simple
sampled grating design, in which most of the mirror region has
no grating.
The SSGDBR was the first widely tunable laser structure to
provide full wavelength coverage over more than 30 nm with
992
IEEE JOURNAL ON SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 6, NO. 6, NOVEMBER/DECEMBER 2000
(a)
(b)
Fig. 4. Early SGDBR laser results. (a) Four-section schematic and illustration of differing multielement mirror reflection spectra used for vernier tuning [45]; (b)
three-section ridge-waveguide laser results—schematic; spectra with different mirror currents; and summary of wavelengths and SMSR [48].
good SMSR [77]. This range improved to over 60 nm with further refinement [78]. (Discontinuous ranges have exceeded 100
nm.) Research prototypes of this device have been available
from NEL for a couple of years. However, output powers continue to be limited, perhaps due to excessive mirror losses.
Very soon after the first viable SGDBR results were published, the first 1550-nm lasers incorporating grating-assisted
codirectional couplers (GACC) were demonstrated [52]. A discontinuous tuning range of 57 nm was reported; however, the
SMSR was 25 dB over much of the range. This soon improved
to more acceptable levels, but sporadic tuning characteristics of
this vertical-coupler filter (VCF) laser seemed to be inherent.
Fig. 8 gives some of the best results reported [54].
As also illustrated in Fig. 8, the wide tuning range in this case
is due to the enhanced tuning of the filter peak in a GACC, which
is placed in the center of the VCF laser. This enhanced tuning
derives from the fact that the center frequency tunes as the index
change in one guide relative to the difference in modal indexes
between the two guides, rather than relative to the starting index,
as in grating mirrors or other phase shifting elements [52], [79].
COLDREN: MONOLITHIC TUNABLE DIODE LASERS
993
(a)
(b)
Fig. 5. Recent SGDBR laser results showing 72 nm of full-wavelength coverage (180 ITU-50 GHz channels) with good SMSR. (a) Mirror tuning currents versus
wavelength and (b) superimposed spectra. (Courtesy of Agility Communications, Inc.)
Thus, the tuning enhancement is given by
),
the index of the tunable guide divided by the difference in modal
group indexes. This factor can easily be ten times or more. Unfortunately, the GACC filter bandwidth also is proportional to
. Thus, as is increased more axial modes of the laser tend to
fall under the filter passband and become candidates for lasing.
More specifically, the filter bandwidth for the GACC is given
by
(5)
is the GACC length. The mode spacing is still given
where
by (4) as always. Thus, the number of modes within the filter
passband is
(6)
, so for
10, 30, or more modes
For typical devices,
might exist within the filter bandwidth! Of course, good SMSR
can be obtained with only a slight increase in cavity loss, and
5 is still interesting, but it is very difficult to obtain an
SMSR 30 dB for all modes across the spectrum, and this is
the minimum required in most systems. A final problem with
the simple VCF laser is an enhanced sensitivity to GACC tuning
current noise that is also proportional to . This is not the case
in the vernier-enhanced lasers, since each mirror still tunes in
direct proportion to the index change.
The solution to this GACC filter bandwidth problem, as suggested in [80], was to add a SGDBR grating for one mirror in
combination with the GACC. This approach was also analyzed
in [49] and found to provide much better SMSR because near-in
modes were not reflected by the SGDBR mirror. Also, since the
primary filter is now the SGDBR, the enhanced tuning of the
GACC does not translate into greater sensitivity to tuning current noise, etc. The first good results with this so called GCSR
(grating-coupled sampled-reflector) laser were reported in [55].
The use of a SSGDBR back mirror was used in intermediate
work to show full coverage over a range of 40-nm [81] and
114-nm discontinuous tuning [56]. More recent work has returned to the use of the simpler SGDBR, which provides equally
994
IEEE JOURNAL ON SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 6, NO. 6, NOVEMBER/DECEMBER 2000
(a)
(b)
(c)
Fig. 6. Schematics and results of monolithic integration of SGDBR laser with: (a) wavelenth monitor [74], (b) electroabsorption modulator [70], and (c)
semiconductor amplifier [71].
good performance for tuning ranges 40 nm [82]. Fig. 9 illustrates recent results.
As illustrated in Fig. 9, the GCSR structure is relatively
complex with two vertical waveguides, three different bandgap
regions, three changes in lateral structure, and two different
gratings. It is significantly more difficult to fabricate than the
SGDBR laser, for example. Nevertheless, significant efforts
have led to relatively good performance recently. In its current
configuration the integration with modulators, amplifiers, etc.,
as illustrated in Fig. 6 would also appear to be quite difficult.
The final monolithic tunable laser effort worth mentioning
here is the effort to make 1550-nm tunable VCSELs. Sig-
COLDREN: MONOLITHIC TUNABLE DIODE LASERS
995
nificant benefits might result if such devices were viable.
If manufactured similarly to the existing GaAs devices, the
costs of production might be significantly lower, and vertical
integration with other components might be easier. Therefore,
a number of research efforts to create such a device have been
undertaken. However, at this writing there has not been any
report of a monolithic 1550-nm VCSEL with good tunability,
let alone any proof of viability. There have been reports of
reasonable 1550-nm VCSELs with fused mirrors [83] (which
are really outside of our definition of monolithic), and there
have been some initial reports of single-growth step [84]–[86]
and even all-epitaxial structures [87], [88] which have had more
marginal performance, but none of these have been tunable.
There are also reports of optically pumped tunable devices at
1550 nm with promising characteristics, but these require a
costly external pump source [89]. Thus, the quest to develop a
viable monolithic tunable VCSEL continues to be a speculative
research effort at this point in time.
(a)
IV. SUMMARY AND CONCLUSION
(b)
(c)
Fig. 7. SSGDBR laser and example results. (a) Schematic; (b) tuning currents;
and (c) superimposed spectra. (Courtesy of NEL.)
Monolithic tunable lasers are being developed in various
versions. Soon there will be a number of modestly tunable
(8–10-nm range) structures qualified for systems insertion.
Most will use a three-section DBR configuration. Some may
add monolithic modulators or SOAs. For larger net wavelength
coverage, some will employ arrays of such devices, and some of
these will use arrays of more modestly tunable DFB elements.
Widely tunable lasers have also arrived. At this writing there
appear to be two viable approaches: the multielement mirror
(SGDBR or SSGDBR) with vernier tuning approach and the
GACC SGDBR GCSR approach. Both have shown over a
100 nm of tuning range; both have shown more than 60 nm of
full wavelength coverage with high SMSR; both have been commercialized and should be available in quantity in 2001; both
have four electrodes to control. Well, it all sounded great up
to that last point—four electrodes—I guess we need to discuss
control circuits a little. But first, the differences: the SGDBR
would appear to be the simplest to produce, e.g., a single waveguide, only one or two regrowths, common DBR processing;
the SGDBR has provided higher output power [90]; and the
SGDBR can easily be integrated with modulators, amplifiers,
monitors, etc. Okay, so these aren’t differences; they are my
clear bias in favor of the SGDBR!
The experiences of the past decade have proven that system
engineers will not likely be interested in a four-section device
with four electrodes to control as a product. They generally want
a module which includes a complete control circuit, so that the
user need only input the desired wavelength and power—the
module provides what is requested. The second choice would
be a four-section device with control hardware, firmware, and
software defined, so that the system designer could incorporate
it onto their board. Recently, there has been a fair amount of discussion of control circuits and/or algorithms for these four-eyed
animals [91], [92]. However, it would appear that the more interesting developments are being held as the propriety property
of the several companies that are marketing these things. I guess
they are really getting real!
996
IEEE JOURNAL ON SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 6, NO. 6, NOVEMBER/DECEMBER 2000
(a)
(b)
(c)
Fig. 8. (a) Schematic of VCF laser, (b) illustration of gain, filter, and cavity mode spectra, and (c) wavelength tuning. [Reprinted with permission from Applied
Physics Letters, vol. 64, 2764–2766, 1994.]
Fig. 9. GCSR laser: (a) schematic and (b) tuning results. (Courtesy of Altitun.)
COLDREN: MONOLITHIC TUNABLE DIODE LASERS
For a summary of the theoretical aspects of these devices as
well as some design examples, the reader is referred to [93] and
[94].
ACKNOWLEDGMENT
Figures supplied by NEL, Altitun, and Agility Communications are gratefully acknowledged.
REFERENCES
[1] Y. Abe, K. Kishino, Y. Suematsu, and S. Arai, “GaInAsP/InP integrated
laser with butt-jointed built-in distributed-Bragg-reflection waveguide,”
Electron. Lett., vol. 17, no. 25, pp. 945–947, 1981.
[2] Y. Tohmori et al., “Novel structure GaInAsP/InP 1.5–1.6 m bundle
integrated-guide (BIG) distributed Bragg reflector laser,” Jpn. J. Appl.
Phys., vol. 24, no. 6, pp. L399–L401, 1985.
[3] Y. Tohmori, Y. Suematsu, Y. Tushima, and S. Arai, “Wavelength tuning
of GaInAsP/InP integrated laser with butt-jointed built-in distributed
Bragg reflector,” Electron. Lett., vol. 19, no. 17, pp. 656–657, 1983.
[4] Y. Tohomori et al., “Wavelength tunable 1.5 m GaInAsP/InP bundleintegrated-guide distributed Bragg reflector (BIG-DBR) lasers,” Trans.
IECE Jpn., vol. E68, no. 12, pp. 788–789, 1985.
As in[5] H. Kawanishi, Y. Suematsu, and K. Kishino, “GaAs–Al Ga
tegrated twin-guide lasers with distributed Bragg reflectors,” IEEE J.
Quantum Electron., vol. QE-12, no. 2, pp. 64–65, 1977.
[6] L. A. Coldren, B. I. Miller, K. Iga, and J. A. Rentschler, “Monolithic
two-section GaInAsP/InP active-optical-resonator devices formed with
RIE mirrors,” Appl. Phys. Lett., vol. 38, no. 5, pp. 315–317, 1981.
[7] L. A. Coldren, K. Furuya, B. I. Miller, and J. A. Rentschler, “Etched
mirror and groove-coupled GaInAsP/InP laser devices for integrated optics,” IEEE J. Quantum Electron., vol. QE-18, pp. 1679–1688, 1982.
[8] K. J. Ebeling, L. A. Coldren, B. I. Miller, and J. A. Rentschler,
“Generation of single-longitudinal-mode subnanosecond light pulses
by high-speed current modulation of monolithic two-section semiconductor lasers,” Electron. Lett., vol. 18, no. 21, pp. 901–902, 1982.
[9] K. J. Ebeling, L. A. Coldren, B. I. Miller, and J. A. Rentschler,
“Single-mode operation of coupled-cavity GaInAsP/InP semiconductor
lasers,” Appl. Phys. Lett., vol. 42, pp. 6–8, 1983.
[10] L. A. Coldren, K. J. Ebeling, B. I. Miller, and J. A. Rentschler, “Singlelongitudinal-mode operation of two-section GaInAsP/InP lasers under
pulsed excitation,” IEEE J. Quantum Electron., vol. QE-19, no. 6, pp.
1057–1062, 1983.
[11] W. T. Tsang, N . A. Olsson, and R. A. Logan, “High-speed direct singlefrequency modulation with large tuning rate and frequency excursion
in cleaved-coupled-cavity semiconductor lasers,” Appl. Phys. Lett., vol.
42, no. 8, pp. 650–652, 1983.
[12] W. T. Tsang, “The cleaved-coupled-cavity (C ) laser,” Semiconductors
and Semimetals, vol. 22, pp. 257–373, 1985.
[13] L. A. Coldren, K. J. Ebeling, R. G. Swartz, and C. A. Burrus, “Stabilization and optimum biasing of dynamic-single-mode coupled cavity
lasers,” Appl. Phys. Lett., vol. 44, pp. 169–171, 1984.
[14] L. A. Coldren, G. D. Boyd, J. E. Bowers, and C. A. Burrus, “Chirp reduction in modulated three-terminal coupled-cavity lasers,” in IEEE Int.
Laser Conf. Proc., Brazil, 1984.
[15]
, “Reduced dynamic linewidth in three-terminal two-section diode
lasers,” Appl. Phys. Lett., vol. 46, pp. 125–127, 1985.
[16] K. J. Ebeling and L. A. Coldren, “Wavelength self-stabilization of coupled-cavity semi-conductor lasers,” Electron. Lett., vol. 20, pp. 69–70,
1984.
[17] L. A. Coldren, K. J. Ebeling, J. A. Rentschler, and C. A. Burrus, “Continuous operation of monolithic dynamic-single-mode coupled-cavity
lasers,” Appl. Phys. Lett., vol. 44, no. 4, pp. 368–370, 1984.
[18] L. A. Coldren, T. L. Koch, T. J. Bridges, E. G. Burkhardt, B. I. Miller,
and J. A. Rentschler, “Etched-groove coupled-cavity vapor-phase transported (VPTBH) window lasers at 1.55m,” Appl. Phys. Lett., vol. 46,
pp. 5–7, 1985.
[19] Y. Tohmori et al., “Wavelength stabilization of 1.5 m GaInAsP/InP
bundle-integrated-guide distributed Bragg reflector (BIG-DBR) lasers
integrated with wavelength tuning region,” Electron. Lett., vol. 22, no.
3, pp. 138–140, 1986.
[20] S. Murata, I. Mito, and K. Kobayashi, “Over 720 GHz (5.8 nm) frequency tuning by a 1.5 m DBR laser with phase and Bragg wavelength
control regions,” Electron. Lett., vol. 23, pp. 403–405, 1987.
997
[21] S. Murata, I. Mito, and K. Kobayashi, “Tuning ranges for 1.5 m wavelength tunable DBR lasers,” Electron. Lett., vol. 33, pp. 210–211, 1997.
[22] Y. Kotaki, M. Matsuda, H. Ishikawa, and H. Imai, “Tunable DBR laser
with wide tuning range,” Electron. Lett., vol. 24, pp. 503–505, 1988.
[23] K. Kobayashi and I. Mito, “Single frequency and tunable laser diodes,”
J. Lightwave Technol., vol. 6, pp. 1623–1633, 1988.
[24] K. Kobayashi and I. Mito, “High light power single-longitudinal-mode
semiconductor laser diodes,” J. Lightwave Technol., vol. LT-3, pp.
1202–1210, 1985.
[25] K. Komori et al., “Single mode properties of distributed-reflector laser,”
IEEE J. Quantum Electron., vol. 25, no. 6, pp. 1235–1244, 1989.
[26] L. D. Westbrook, A. W. Nelson, P. J. Fiddyment, and J. V. Collins,
“Monolithic 1.5 m hybrid DFB/DBR lasers with 5 nm tuning range,”
Electron. Lett., vol. 20, pp. 957–959, 1984.
[27] B. Broberg and S. Nilsson, “Widely tunable active Bragg reflector
integrated lasers in InGaAsP–InP,” Appl. Phys. Lett., vol. 52, pp.
1285–1287, 1988.
[28] T. L. Koch, U. Koren, and B. I. Miller, “High performance tunable
1.5 m InGaAs/InGaAsP multiple quantum well distributed feedback
Bragg reflector lasers,” Appl. Phys. Lett., vol. 53, pp. 1036–1038, 1988.
[29] T. L. Koch, U. Koren, R. P. Gnall, C. A. Burrus, and B. I. Miller, “Continuously tunable 1.5 m multiple-quantum-well GaInAs/GaInAsP distributed-Bragg-reflector lasers,” Electron. Lett., vol. 24, pp. 1431–1433,
1988.
[30] L. A. Coldren and S. W. Corzine, “Continuously-tunable single-frequency semiconductor lasers,” IEEE J. Quantum Electron., vol. 23, pp.
903–908, June 1987.
[31] B. Stoltz, M. Dasler, and O. Sahlen, “Low threshold-current, wide
tuning-range, butt-joint DBR laser grown with four MOVPE steps,”
Electron. Lett., vol. 29, pp. 700–702, 1993.
[32] F. Delorme, S. Slempkes, A. Ramdane, B. Rose, and H. Nakjima, “Subnanosecond tunable distributed Bragg reflector lasers with an electrooptical Bragg section,” IEEE J. Select. Topics Quantum Electron., vol. 1,
pp. 396–400, 1995.
[33] F. Delorme, S. Grosmaire, A. Gloukhian, and A. Ougazzaden, “High
power operation of widely tunable 1.55 m distributed Bragg reflector
laser,” Electron. Lett., vol. 33, pp. 210–211, 1997.
[34] Y. Yoshikuni and G. Motosugi, “Multielectrode distributed feedback
laser for pure frequency modulation and chirping suppressed amplitude
modulation,” J. Lightwave Technol., vol. 5, pp. 516–522, 1987.
[35] N. K. Dutta, A. B. Piccirilli, T. Cella, and R. L. Brown, “Electronically tunable distributed feedback lasers,” Appl. Phys. Lett., vol. 48, pp.
1501–1503, 1986.
[36] Y. Kotaki, S. Ogita, M. Matsuda, Y. Kuwahara, and H. Ishikawa, “Tunable narrow-linewidth and high-power /4-shifted DFB laser,” Electron.
Lett., vol. 25, pp. 990–992, 1989.
[37] T. Numai, S. Murata, and I. Mito, “1.5 m wavelength tunable phaseshift controlled distributed feedback laser diode with constant spectral
linewidth in tuning operation,” Electron. Lett., vol. 24, pp. 1526–1528,
1988.
[38] D. Leclerc, J. Jacquet, D. Sigogne, C. Labourie, Y. Louis, C. Artigue, and
J. Benoit, “Three-electrode DFB wavelength tunable FSK transmitter at
1.53 m,” Electron. Lett., vol. 25, pp. 45–47, 1989.
[39] M.-C. Amann, S. Illek, C. Schanen, and W. Thulke, “Tunable twin-guide
laser: A novel laser diode with improved tuning performance,” Appl.
Phys. Lett., vol. 54, pp. 2532–2533, 1989.
, “Tuning range and threshold current of the tunable twin-guide
[40]
(TTG) laser,” IEEE Photon. Technol. Lett., vol. 1, pp. 253–254, 1989.
[41] T. Wolf, S. Illek, J. Rieger, B. Borchert, and M.-C. Amann, “Tunable
twin-guide (TTG) distributed feedback (DFB) laser with over 10 nm
continuous tuning range,” Electron. Lett., vol. 29, pp. 2124–2125, 1993.
[42] T. Wolf, S. Illek, J. Rieger, B. Borchert, and M.-C. Amann, “Extended
continuous tuning range (over 10 nm) of tunable twin-guide lasers,” in
Conf. Lasers Electro-Optics (CLEO ’94).
[43] Y. Sakata, M. Yamaguchi, S. Takano, J.-I. Shim, T. Sasaki, M. Kitamura, and I. Mito, “Novel tunable twin-guide lasers with a carrier-control tuning layer,” in Optical Fiber Conf., San Jose, CA, 1993, pp. 9–10.
[44] L. A. Coldren, “Multi-section tunable laser with differing multi-element
mirrors,” U.S. Patent 4 846 325, 1990.
[45] V. Jayaraman, D. A. Cohen, and L. A. Coldren, “Extended tuning range
semiconductor lasers with sampled gratings,” in Proc. IEEE LEOS ’91,
San Jose, CA, 1991, paper SDL15.5.
[46] V. Jayaraman, L. A. Coldren, S. DenBaars, A. Mathur, and P. D. Dapkus,
“Wide tunability and large mode-suppression in a multi-section semiconductor laser using sampled gratings,” in Integrated Photonics Research ’92, New Orleans, LA, 1992, paper WF1-1.
998
IEEE JOURNAL ON SELECTED TOPICS IN QUANTUM ELECTRONICS, VOL. 6, NO. 6, NOVEMBER/DECEMBER 2000
[47] V. Jayaraman, D. A. Cohen, and L. A. Coldren, “Demonstration of
broadband tunability in a semiconductor laser using sampled gratings,”
Appl. Phys. Lett., vol. 60, no. 19, pp. 2321–2323, 1992.
[48] V. Jayaraman, A. Mathur, L. A. Coldren, and P. D. Dapkus, “Very
wide tuning range in a sampled grating DBR laser,” in 13th IEEE Int.
Semiconductor Laser Conf., Takamatsu, Japan, 1992, postdeadline
paper PD-11.
[49]
, “Theory, design, and performance of extended tuning range in
sampled grating DBR lasers,” IEEE J. Quantum Electron., vol. 29, pp.
1824–1834, June 1993.
[50] H. Ishii, Y. Tohmori, Y. Yoshikuni, T. Tamamura, and Y. Kondo, “Multiple-phase-shift super structure grating DBR lasers for broad wavelength tuning lasers,” IEEE Photon. Technol. Lett., vol. 5, pp. 613–615,
1993.
[51] Y. Tohmori, Y. Yoshikuni, H. Ishii, F. Kano, T. Tamamura, Y. Kondo, and
M. Yamamoto, “Broadrange wavelength-tunable superstructure grating
(SSG) DBR lasers,” IEEE J. Quantum Electron., vol. 29, pp. 1817–1823,
1993.
[52] R. C. Alferness, U. Koren, L. L. Buhl, B. I. Miller, M. G. Young, T. L.
Koch, G. Raybon, and C. Burrus, “Broadly tunable InGaAsP/InP laser
based on a vertical coupler filter with 57-nm tuning range,” Appl. Phys.
Lett., vol. 60, pp. 3209–3211, 1992.
[53] Z.-M. Chuang and L. A. Coldren, “Widely tunable semiconductor lasers
using grating-assisted codirectional coupler filters,” in SPIE OCCC ’92,
Hsinchu, Taiwan, Dec. 1992, paper 1813-44.
[54] I. Kim, R. C. Alferness, U. Koren, L. L. Buhl, B. I. Miller, M. G.
Young, M. D. Chien, T. L. Koch, H. M. Presby, G. Raybon, and C.
A. Burrus, “Broadly tunable vertical-coupler filtered tensile-strained
InGaAs/InGaAsP multiple quantum well laser,” Appl. Phys. Lett., vol.
64, pp. 2764–2766, 1994.
[55] M. Öberg, S. Nilsson, K. Streubel, J. Wallin, L. Bäckbom, and T. Klinga,
“74 nm wavelength tuning range of an InGaAsP/InP vertical grating assisted codirectional coupler laser with rear sampled grating reflector,”
IEEE Photon. Technol. Lett., vol. 5, pp. 735–738, 1993.
[56] P.-J. Rigole, S. Nilsson, L. Bäckbom, T. Klinga, J. Wallin, B. Stålnacke,
E. Berglind, and B. Stoltz, “114 nm wavelength tuning range of a vertical grating assisted codirectional coupler laser with a super structure
grating distributed Bragg reflector,” IEEE Photon. Technol. Lett., vol. 7,
pp. 697–699, 1995.
[57] R. J. Lang, A. Yariv, and J. Salzman, “Laterally coupled-cavity semiconductor lasers,” IEEE J. Quantum Electron., vol. 23, pp. 395–400, 1987.
[58] M. Kuznetsov, P. Verlangieri, A. G. Dentai, C. H. Joyner, and C. A.
Burrus, “Widely tunable (45 nm, 5.6 THz) multi-quantum-well threebranch Y3-lasers for WDM networks,” IEEE Photon. Technol. Lett., vol.
5, pp. 879–882, 1993.
[59] O. Hildebrand, M. Schilling, D. Baums, W. Idler, K. Dütting, G. Laube,
and K. Wünstel, “The Y-laser: A multifunctional device for optical communication systems and switching networks,” J. Lightwave Technol.,
vol. 11, pp. 2066–2075, 1993.
[60] M. C. Larson and J. S. Harris, “Wide and continuous wavelength tuning
in a vertical-cavity surface-emitting laser using a micromachined deformable-membrane mirror,” Appl. Phys. Lett., vol. 68, pp. 891–893,
1996.
[61] F. Sugihwo, M. C. Larson, and J. S. Harris, “Simultaneous optimization
of membrane reflectance and tuning voltage for tunable vertical cavity
lasers,” Appl. Phys. Lett., vol. 72, pp. 10–12, 1998.
[62] E. C. Vail, G. S. Li, W. Yuen, and C. J. Chang-Hasnain, “High performance micromechanical tunable vertical cavity surface emitting lasers,”
Electron. Lett., vol. 32, pp. 1888–1889, 1996.
[63] M. Li, W. Yuen, G. S. Li, and C. J. Chang-Hasnain, “Top-emitting micromechanical VCSEL with a 31.6 nm tuning range,” IEEE Photon.
Technol. Lett., vol. 10, pp. 18–20, 1998.
[64] H. Okuda, Y. Hirayama, H. Furuyama, J.-I. Kinoshita, and M. Nakamura, “Five-wavelength integrated DFB laser arrays with quarter-waveshifted structures,” IEEE J. Quantum Electron., vol. 23, pp. 843–848,
1987.
[65] M. Nakao, K. Sato, T. Nishida, and T. Tamamura, “Distributed feedback
laser arrays fabricated by synchrotron orbital radiation lithography,”
IEEE J. Select. Areas Commun., vol. 8, pp. 1178–1182, 1990.
[66] C. E. Zah, B. Pathak, F. Favire, R. Bhat, C. Caneau, P. S. D. Lin, A. S.
Gozdz, N. C. Andreadakis, M. A. Koza, and T. P. Lee, “1.5 m tensilestrained single quantum well 20-wavelength distributed feedback laser
arrays,” Electron. Lett., vol. 28, pp. 1585–1587, 1992.
[67] M. G. Young, U. Koren, B. I. Miller, M. Chien, T. L. Koch, D. M. Tennant, K. Feder, K. Dreyer, and G. Raybon, “Six wavelength laser arrays
with integrated amplifier and modulator,” Electron. Lett., vol. 31, pp.
1835–1836, 1995.
[68] C. E. Zah, F. Favire, B. Pathak, R. Bhat, C. Caneau, P. S. D. Lin, A. S.
Gozdz, N. C. Andreadakis, M. A. Koza, and T. P. Lee, “Monolithic integration of multiwavelength compressive-strained multiquantum-well
distributed-feedback laser array with star coupler and optical amplifiers,” Electron. Lett., vol. 28, pp. 2361–2362, 1992.
[69] M. Zirngibl, C. H. Joyner, C. R. Doerr, L. W. Stultz, and H. M. Presby,
“An 18-channel multifrequency laser,” IEEE Photon. Technol. Lett., vol.
8, pp. 870–872, 1996.
[70] B. Mason, G. Fish, S. DenBaars, and L. A. Coldren, “Widely tunable
sampled-grating DBR laser with integrated elecgtroabsorption modulator,” IEEE Photon. Technol. Lett., vol. 11, pp. 638–640, June 1999.
[71] B. Mason, G. A. Fish, V. Kaman, J. Barton, L. A. Coldren, S. P. DenBaars, and J. E. Bowers, “Characteristics of sampled grating DBR lasers
with integrated semiconductor optical amplifiers and electroabsorption
modulators,” in Proc. Optical Fiber Communications Conf., Baltimore,
MD, Mar. 2000, Paper TuL6.
[72] B. Mason, G. A. Fish, and S. P. DenBaars, “Ridge waveguide sampledgrating DBR lasers with 22-nm quasi-continuous tuning range,” IEEE
Photon. Technol. Lett., vol. 11, pp. 1211–1213, Sept. 1998.
[73] D. J. Robbins, N. D. Whitbread, P. J. Williams, and J. R. Rawsthorne,
“Design and optimization of sampled-grating DBR lasers for dense
WDM networks,” in ECOC’98, Madrid, Spain, 1998.
[74] B. Mason, S. P. DenBaars, and L. A. Coldren, “Tunable sampled-grating DBR lasers with integrated wavelength monitors,” IEEE
Photon. Technol. Lett., vol. 10, pp. 1085–1087, Aug. 1988.
[75] H. Ishii, Y. Tohmori, M. Yamamoto, T. Tamamura, and Y. Yoshikuni,
“Modified multiple-phase-shift super-structure-grating DBR lasers
for broad wavelength tuning,” Electron. Lett., vol. 30, no. 14, pp.
1141–1142, 1994.
[76] H. Ishii, H. Tanobe, F. Kano, Y. Tohmori, Y. Kondo, and Y. Yoshikuni,
“Quasicontinuous wavelength tuning in super-structure-grating (SSG)
DBR lasers,” IEEE J. Quantum Electron., vol. 32, pp. 433–441, Mar.
1996.
[77] H. Ishii, F. Kano, Y. Tohmori, Y. Kondo, T. Tamamura, and Y.
Yoshikuni, “Broad range (34nm) quasi-continuous wavelength tuning
in super-structure-grating DBR lasers,” Electron. Lett., vol. 30, no. 14,
pp. 1134–1135, 1994.
[78] H. Ishii, T. Tanobe, F. Kano, Y. Tohmori, Y. Kondo, and Y. Yoshikuni,
“Broad-range wavelength coverage (62.4 nm) with superstructure-grating DBR laser,” Electron. Lett., vol. 32, pp. 454–455, 1996.
[79] Z.-M. Chuang and L. A. Coldren, “Design of widely tunable semiconductor lasers using grating-assisted codirectional-couplers filters,” IEEE
J. Quantum Electron., vol. 29, no. 4, pp. 1071–1080, 1993.
[80] J. Willems, G. Morthier, and R. Baets, “Novel widely tunable integrated
optical filter with high spectral selectivity,” in 18th Eur. Conf. Opt.
Commun. Proc., Berlin, Germany, 1992, Paper WeB9.2.
[81] M. Oberg, P.-J. Rigole, S. Nilsson, T. Klinga, L. Backbom, K. Streubel,
J. Wallin, and T. Kjellberg, “Complete single mode wavelength coverage over 40 nm with a super structure grating DBR laser,” J. Lightwave Technol., vol. 13, pp. 1892–1898, 1995.
[82] P.-J. Rigole, S. Nilsson, L. Backbom, B. Stalnacke, E. Berglind, J.-P.
Weber, and B. Stoltz, “Quasi-continuous tuning range from 1560 to 1520
nm in a GCSR laser, with high power and low tuning currents,” Electron.
Lett., vol. 32, pp. 2352–2354, Dec. 1996.
[83] K. A. Black, P. Abraham, A. Keating, Y. J. Chiu, E. L. Hu, and J. E.
Bowers, “Improved luminescence from InGaAsP/InP MQW active regions using a wafer fused superlattice barrier,” in IPRM Conf. Proc.,
1999, pp. 271–276.
[84] J. Boucart, C. Starck, F. Gaborit, A. Plais, N. Bouche, E. Derouin, L.
Goldstein, C. Fortin, D. Carpentier, P. Salet, F. Brillouet, and J. Jacquet,
“1-mW CW-RT monolithic VCSEL at 1.55 m,” IEEE Photon. Technol.
Lett., vol. 11, pp. 629–631, June 1999.
[85] W. Yuen, G. S. Li, R. F. Nabiev, J. Boucart, P. Kner, R. Stone, D. Zhang,
M. Beaudoin, T. Zheng, C. He, K. Yu, M. Jansen, D. P. Worland, and C.
J. Chang-Hasnain, “High-performance 1.6 m single-epitaxy top-emitting VCSEL,” in Conf. Lasers Electro-Optics Proc., San Francisco, CA,
2000, Paper CPD12.
[86] M. Ortsiefer, R. Shau, G. Bohm, F. Kohler, and M.-C. Amann, “Roomtemperature cw 1.5 m InGaAlAs/InP vertical-cavity laser with high
efficiency,” in IEEE Conf. Lasers Electro-Optics Proc., San Francisco,
CA, 2000, paper CPD11.
[87] J. K. Kim, E. Hall, S. Nakagawa, A. Huntington, and L. A. Coldren,
“Bipolar cascade 1.55 m VCSELs with >1 differential quantum efficiency and CW operation,” in IEEE Int. Semiconductor Laser Conf.
Proc., Monterey, CA, 2000.
COLDREN: MONOLITHIC TUNABLE DIODE LASERS
[88] S. Nakagawa, E. M. Hall, G. Almuneau, J. K. Kim, H. Kroemer, and
L. A. Coldren, “1.55 m, InP-lattice-matched VCSELs operating at RT
under CW,” in IEEE Int. Semiconductor Laser Conf. Proc., Monterey,
CA, 2000.
[89] D. Vakhshoori, J.-H. Zhou, M. Jiang, M. Azimi, K. McCallion, C.-C.
Lu, K. J. Knopp, J. Cai, P. D. Wang, P. Tayebati, H. Zhu, and P. Chen,
“C-band tunable 6mW vertical-cavity surface-emitting lasers,” in Optical Fiber Communication Conf. Proc., Baltimore, MD, 2000, Paper
PD13.
[90] P. J. Williams, D. J. Robbins, F. O. Robson, and N. D. Whitbread, “Highpower and wide quasi-continuous tuning, surface ridge SG-DBR lasers,”
in ECOC 2000 Proc., Munich, Germany, 2000.
[91] J. Dunne, T. Farrell, and R. O’Dowd, “Fast generation of optimum operating points for tuneable SG-DBR laser over 1535–1565 nm range,”
in IEEE Conf. Lasers Electro-Optics Proc., Baltimore, MD, 1999.
[92] G. Sarlet, G. Morthier, and R. Baets, “Wavelength and mode stabilization of widely tunable SG-DBR and SSG-DBR lasers,” IEEE Photon.
Technol. Lett., vol. 11, pp. 1351–1353, Nov. 1999.
[93] L. A. Coldren and S. W. Corzine, Diode Lasers and Photonic Integrated
Circuits. New York: Wiley, 1995, ch. 8.
[94] M.-C. Amann and J. Buus, Tunable Laser Diodes. London, U.K.:
Artech, 1998, ch. 7.
999
Larry A. Coldren (F’82) received the Ph.D. degree
in electrical engineering from Stanford University
in 1972. After 13 years in the research area at
Bell Laboratories, he was appointed Professor
of Electrical and Computer Engineering at the
UC-Santa Barbara in 1984. In 1986, he assumed a
joint appointment with Materials and ECE, and in
2000 the Fred Kavli Chair in Optoelectronics and
Sensors. He is also Chairman and Chief Technology
Officer of Agility Communications, Inc. At UCSB
his efforts have included work on novel guided-wave
and vertical-cavity modulators and lasers as well as the underlying materials
growth and fabrication technology. He is now investigating the integration of
various optoelectronic devices, including optical amplifiers and modulators,
tunable lasers, wavelength-converters, and surface-emitting lasers.
Dr. Coldren has authored or co-authored over 500 papers, 5 book chapters and
1 textbook, and has been issued 32 patents. He is a Fellow of the IEEE and OSA,
a past Vice-President of IEEE-LEOS, and has been active in technical meetings.
He is currently Director of the multicampus DARPA supported Heterogeneous
Optoelectronics Technology Center.