25th International Semiconductor Laser Conference (ISLC 2016)

Final Program
Monday, September 12
All talks will be held in the Zuiten (East) room
11:00-14:00

Technical WS: Power saturation in LDs

Organizers:

Dr. Eugene Avrutin

Dr. Victor Rossin(Univ. of York, UK)(Lumentum Operations LLC)

High power diode lasers provide the optical energy for the majority of high performance laser systems,
and are the most efficient technology for converting electrical energy into useful light. Solid-state andfiber laser systems that make use of such diode lasers as pump sources are progressing rapidly, driven
by improvements to the diode lasers. As their power, efficiency and brightness improve, diode lasers
have been increasingly deployed directly in material processing applications. For future systems, further
enhanced diode lasers are needed, with ever-increasing output power per device, for cost reduction andfor better system performance. However, the limits to peak power remain unclear, with various non-linear
effects coming into play at high bias, driven by a combination of high optical intensity, current density, andtemperature, whose relative importance is challenging to robustly diagnose, especially in these large area
structures where spatial non-uniformity can also play a large role.
This workshop of invited speakers will discuss the efforts underway by various groups to enhance
the peak achievable power in high-power semiconductor lasers, with a special focus on measures
to diagnose and understand the limiting mechanisms. The workshop forum is meant to stimulate
discussion and interaction with the audience to encourage feedback and consensus building among
high-power laser researchers. The workshop will conclude with a panel discussion on how to sustain
continual power scaling for the next generation of diode lasers.
Workshop Chair/Panel Discussion Moderator: Paul Crump (Ferdinand-Braun-Institut)
11:00 WS1 – "High Power Laser Diodes: Motivation and Hurdles"
V. Rossin
Lumentum Operations LLC, USA
11:15 WS2 – "The Role of Carrier Accumulation in the Optical Confinement Layer in Output Efficiency
Deterioration of Laser Diodes"
Eugene A. Avrutin1, Boris S. Ryvkin2
1
University of York, UK, 2A.F.Ioffe Physico-Technical Institute, Russia
Analytical and semi-analytical theory of the effects of carriers in the Optical Confinement Layer on the
output efficiency degradation of high-power diode lasers is summarized. The main sources of carrier
accumulation and the implications for laser design are discussed.
11:30 WS3 – "Linear and Non-linear Loss Mechanisms in High-Power Semiconductor Lasers andOptical Amplifiers"
Toby J. Garrod, J. J. Plant, D. F. Siriani, P. W. Juodawlkis
Massachusetts Institute of Technology, USA
As the intra-cavity and emitted power in optical emitters continues to rise, both linear and nonlinear loss mechanisms contribute to the saturation of emitted power. This paper will discuss thephysical mechanisms that constitute loss in semiconductor emitters, and offer insight into how these14

25th International Semiconductor Laser Conference (ISLC 2016)mechanisms can be mitigated.
11:45 WS4 – "Experimental and Theoretical Studies into the Limits to Peak Power in GaAs-Based
Diode Lasers"
Paul Crump, Hans Wenzel, Thorben Kaul, Goetz Erbert, Guenther Traenkle
Ferdinand-Braun-Institut, Leibniz-Institut für Höchstfrequenztechnik, Germany
An overview is presented of progress in studies to diagnose and address limits to peak power in highpower diode lasers. Key terms in advanced structures include carrier losses in the p-side waveguide,
self-heating effects in the quantum well, and longitudinal spatial hole-burning.
12:00 WS5 – "Power Saturation in Standard and Double-AR Unfolded Laser Diode Cavities"
Matthew Peters1, Arnaud Fily1, Victor Rossin1, Abdullah Demir2
1Lumentum Inc., USA, 2Bilkent Univ., Turkey
We report modeling and experimental results that demonstrate mechanisms limiting the output powerof broad area semiconductor lasers. The modeling comprises numerical simulations with evolutionof non-uniform carrier density, photon density, temperature and index. We measure unfolded laser
cavities to validate simulation methods and parameters.
12:15 WS6 – "Record-Breaking High-Power InGaN-Based Laser-Diodes Using Novel Thick-Waveguide
Structure"
Masao Kawaguchi, Osamu Imafuji, Shinichiro Nozaki, Hiroyuki Hagino, Koshi Nakamura,
Shinichi Takigawa, Takuma Katayama, Tsuyoshi Tanaka
Panasonic Corporation, Japan
High-power operation over 7W in InGaN laser-diodes is achieved by an undoped-thick-waveguidestructure where an optical-loss is suppressed by reduced light-leakage to the absorbing p-cladding.
Operating voltage increase due to the high-resistive undoped-layer is successfully eliminated byutilizing the potential-flattening-effect of electrons reflected from electron-overflow-suppression-layer.
12:30 WS7 – "VCSELs for High Power Applications"
Ulrich Weichmann1, Ralf Conrads1, Carsten Deppe1, Guenther Derra1, Philipp Gerlach1,
Stephan Gronenborn1, Xi Gu2, Johanna Kolb1, Michael Miller1, Holger Moench1, Pavel Pekarski1,
Jens Pollmann-Retsch1, Armand Pruijmboom2
1
Philips Photonics, Germany, 2Philips Photonics, The Netherlands
High power VCSEL systems are novel laser sources, offering a unique combination of efficiency,
compactness and robustness. Wide scalability of these systems in power makes them attractive forapplications in industrial manufacturing. Basic properties and first applications of high power VCSEL
systems are presented here.
12:45 WS8 – "Improvement of High Power Operation in 9××nm Broad Area Laser Diodes"
Yuji Yamagata1, Yumi Yamada1, Yoshikazu Kaifuchi2, Ryozaburo Nogawa2, Rintaro Morohashi2,
Masayuki Yamaguchi2
1
Optoenergy, Inc., Japan, 2Fujikura Ltd., Japan
Improvement of high power and high efficiency operation 9xx-nm broad area laser diodes are
discussed. For the output power maximization, power saturation phenomenon is experimentallyinvestigated. Power saturation is found to be governed by not only junction temperature but also by
thermal lensing effect.

13:00-14:00

Panel Discussion (Lunch box is served)
14:00-14:20 Break15

25th International Semiconductor Laser Conference (ISLC 2016)

14:20-16:20

Anniversary WS 1

Session Co-Chairs: Yuichi Tohmori (Tsurugi Photonics Foundation)
Kent Choquette (Univ. of Illinois)In the Anniversary Workshop, twelve invited speakers will review the progress of the technology
leading to the now in their research fields, and more will speak about the future possibilities in thisfield. Anniversary Workshop will be held in Sept. 12 and 14.
14:20 AWS1 (Invited) – "Diode Laser Active Region Evolution"Peter Zory
Univ. of Florida, USA
Laser beams generated in the p-n junction (active) regions of forward biased GaAs diode chips
were first observed in September 1962. The active region width ‘d’ in these Zn-diffused chips was
about 2 microns. By 1966, the diffusion technique had been replaced by a liquid phase epitaxy (LPE)
growth technique. The higher quality LPE material led to chips capable of pulsed operation at room
temperature (300 K) and commercialization.
At the first International Semiconductor Laser Conference (ISLC-1) held in Las Vegas in 1967, it wasreported that forward-biased diode chips made from LPE-grown AlGaAs lased when immersed in liquid
nitrogen (77 K). By 1968 this breakthrough had given birth to the single heterojunction (SH) laser; by
1969, the double heterojunction (DH) laser and by 1970, continuous wave (CW) operation at 300 K.
With the advent of the DH structure, the active region concept crystalized to that of a gain layer ofthickness ‘d’ enclosed in a waveguide that determined the spatial aspect of the laser beam. For the
next 20 years or so, new material growth and processing techniques led to ‘d’ values decreasing fromabout 100 nm to a few nanometers and waveguides evolving from simple to complex. In this talk,highlights from the twelve ISLCs held between 1967 and 1990 will be selected to illustrate this active
region evolution.
14:50 AWS2 (Invited) – "The History of Laser Emission on Silicon"
John E. Bowers
Univ. of California, Santa Barbara, USA
Fifty years ago the birth of the laser started a scientific and technological revolution. Two years later
diode lasers were demonstrated in III-V compound semiconductors while Si-based transistor radiosachieved mass popularity. In an effort to join the laser and transistor revolutions together, many
scientists have researched lasing on silicon substrates. Recently, rapid advances in silicon photonics
are being driven by a combination of a need for more complex, higher functionality and lower costphotonics integrated circuits, but also by pin count and power limits for communications. Electronics
giants, including Intel, IBM, HPE, Oracle, ST Microelectronics, AIM Photonics, IMEC and Alcatel-Thales,
have teamed up with research institutes around the world to drive progress in silicon photonics. The
momentum to make a useful laser in or on silicon is significant. We describe research on lasers in oron silicon, including efforts to grow III-V on silicon, bond III-V on silicon, nanostructure silicon, use
the Raman or Brillouin gain in silicon, and to use Ge and other group IV elements to make lasers on
silicon. This research should lead to low-cost, terabit-level optical data pipes inside computers and data
centers.

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25th International Semiconductor Laser Conference (ISLC 2016)

15:20 AWS3 (Invited) – "Progress in Quantum Well and Dot Lasers"
Yasuhiko Arakawa
The Univ. of Tokyo, Japan
In the history of semiconductor lasers, the quantum-size effect is one of important physics which gavea great impact on enhancement of lasing characteristics. For the period of more than 10 years fromlate 1970’s, quantum well lasers were intensively investigated both theoretically and experimentally[1,2]. Nowadays, almost all active layers of semiconductor lasers including blue GaN lasers consist of
the quantum wells.
In 1982, the concept of quantum dot lasers was proposed with theoretical prediction of temperature
insensitivity of threshold current by Arakawa and Sakaki [3]. The temperature insensitivity was
successfully demonstrated in a self-assembled InAs/GaAs quantum dot laser in 2006 by Fujitsu andthe Univ. of Tokyo [4]. This achievement was led to launch of a venture company named QD Laser
Inc.. The quantum dot lasers have a variety of superior performance to conventional lasers such as
high temperature operation, low-power consumption, and low-cost productivity. Silicon photonics is apromising application for the quantum dot lasers.
In this presentation, we overview historical progress and the current state of the art of the quantum
dot lasers. Future prospects of quantum dot photonics are also discussed.
References[1] 1. P. van der Ziel, R. Dingle, R. C. Miller, W. Wiegmann, and W. A. Nordland Jr., Appl. Phys. Lett.. 26,
463 (1975)[2] Y. Arakawa and A. Yariv, IEEE J. of Quant. Electron. 22 1887 (1986)[3] Y. Arakawa and H. Sakaki, Appl. Phys. Lett. 40, 939 (1982)
15:50 AWS4 (Invited) – "Progress and Future Prospects of Photonic Crystal Lasers"
Susumu Noda
Kyoto Univ., JapanThe band-edge of two-dimensional (2D) photonic-crystal (PC), at which a group velocity of lightbecomes zero, can be utilized to realize a broad-area coherent 2D cavity mode, which enables a stablesingle longitudinal & lateral 2D lasing oscillation for semiconductor lasers. The 2D cavity mode can becoupled out to the direction normal to the PC plane by PC itself, which enables 2D surface-emitting
operation. The first semiconductor laser based on this principle was realized in 1999, and very recently,
watt-class high-power, high-beam-quality, surface-emitting lasing oscillation has been successfully
achieved under room temperature (RT), continuous-wave (CW) condition. This laser possesses uniqueproperties including generation of unique beams with controlled polarization and patterns ranging
from circular to ring-shapes with very narrow divergence angles. Moreover, an extension of lasing
wavelength to a blue-violet regime has been achieved, and even electronically-driven 1D and 2D beamsteering operation can be realized. In this conference, I will review the progress and future prospects ofsuch photonic crystal lasers.

16:20-16:40 Coffee Break17

25th International Semiconductor Laser Conference (ISLC 2016)

16:40-18:40

Anniversary WS 2

Session Co-Chairs: Luke J. Mawst (Univ. of Wisconsin)
Akihiko Kasukawa (Furukawa Electric Co., Ltd.)
16:40 AWS5 (Invited) – "VCSEL Odyssey ++ -The Conception and Research of Vertical Cavity Surface
Emitting Laser- "Kenichi Iga
Tokyo Institute of Technology, JapanThe author obtained the conception of Vertical Cavity Surface Emitting Laser (VCSEL) in March 22,
1977. The first presentation of idea was in 1978 and the initial device came out in 1979 operating at
77K by GaInAsP/InP material. The primary innovation was 6-micron cavity VCSEL demonstrating clear
VCSEL mode even at 77K in 1982; i.e., single mode, circular beam, linear polarization, and so on. The
first room temperature CW operation was achieved in 1988 by GaAs system with F. Koyama exhibiting
a possibly engineered semiconductor laser. Also, we achieved a first room temperature CW in a 1,300
nm VCSEL in 1992. The other important event in 1990 was the demonstration of a continuously tunable
VCSEL by the use of mechanically changing the cavity length. Later, this concept led to a MEMS tunable
VCSEL Since the beginning of 1990’s, a lot of research sectors started the development of VCSEL andvery low threshold devices reaching several micro-Amperes were reported. From 1999, VCSELs wereapplied to high speed LANs such as Gigabit Ethernet. Until now VCSELs have been applied to multiGigabit LANs, SANs, computer mice, optical interconnects in super computers, arrayed-laser printers,
sensors, engine igniters, and various green IOT fields. The market size of production is postulated to be
2,500 M$ in 2020. The future of VCSELs may be opened to very low power consumption applications
such as laser eye glasses, very high power photonics like laser manufacturing, laser displays, laser
radars, and so on.
17:10 AWS6 (Invited) – "Long-Wavelength VCSELs: Devices and Applications"Markus C. Amann
Technical Univ. Munich, Germany
Vertical-Cavity Surface-Emitting Lasers (VCSELs) exhibit attractive device features such as sub-milliamp
threshold currents, low beam divergence, simple fiber-coupling, high slope efficiencies and low power
consumption. Differing from their rather mature 850-950 nm counterparts, longwavelength (䡡䡡䡡䡡1.3ʅŵͿs^>ƐŽŶůǇŚĂǀĞďĞĐŽŵĞĂƉƉůŝĐĂƚŝŽŶͲƐƵŝƚĞĚŝŶƌĞĐĞŶƚǇĞĂƌƐ͘dŽĚĂǇ͕/ŶWďĂƐĞĚs^>ƐďĂƐĞĚŽŶƚŚĞ
buried tunnel junction technology show excellent device performance.
dŚĞƐĞDͲŐƌŽǁŶĚĞǀŝĐĞƐĂĐĐĞƐƐƚŚĞĞŶƚŝƌĞŶĞĂƌͲŝŶĨƌĂƌĞĚǁĂǀĞůĞŶŐƚŚƌĂŶŐĞĨƌŽŵϭ͘ϯƚŽϮ͘ϲʅŵ͘dŚĞǇ
yield stable polarization, single-mode operation, high-speed modulation exceeding 20 GHz and simple
electro-thermal tuning over several nanometers. Digital transmission systems with data rates exceedingϱϬ'ďͬƐĂƚϭ͘ϱϱʅŵǁĞƌĞĚĞŵŽŶƐƚƌĂƚĞĚĂŶĚŶƵŵĞƌŽƵƐƚƌĂĐĞŐĂƐƐƉĞĐŝĞƐŚĂǀĞďĞĞŶŵĞĂƐƵƌĞĚǁŝƚŚsensing systems based on these lasers. While the InP-based laser diodes are limited to an upperǁĂǀĞůĞŶŐƚŚŽĨĂďŽƵƚϮ͘ϲʅŵ͕ĂƉƉůŝĐĂƚŝŽŶŽĨ'Ă^ďͲďĂƐĞĚŚĞƚĞƌŽƐƚƌƵĐƚƵƌĞƐŽƉĞŶƐƚŚĞϮͲϰʅŵǁĂǀĞůĞŶŐƚŚƌĂŶŐĞ͘&ŝƌƐƚ'Ă^ďͲs^>ƐĨŽƌƚŚĞǁĂǀĞůĞŶŐƚŚƌĂŶŐĞĨƌŽŵϮ͘ϯƚŽϯʅŵŚĂǀĞďĞĞŶƌĞĂůŝǌĞĚƐŽĨĂƌ͘
These early devices already show continuous-wave operation and stable single-mode emission. The
electro-thermal tuning is about a factor of two stronger than for their InP-based counterparts andtuning ranges of the order of 10 nm have been achieved.
17:40 AWS7 (Invited) – "A 1989 Event in VCSEL Development"
Jack L. Jewell
USA
Prior to mid-1989, essentially all reported VCSELs had active regions a micron or more thick (one had
0.6um). Then a Bell Labs / Bellcore group (Jewell, et al., Electronics Letters, vol. 25, p. 1123, 1989),
reported VCSELs with 3 (and subsequently 1) quantum wells (QWs) confined to a single standing-wave
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25th International Semiconductor Laser Conference (ISLC 2016)

intensity peak (f40X reduction in thickness). Not long after that publication, essentially all VCSELs
had similar active regions comprising f1-4 QWs. With active regions similar to those of edge-emitters,
VCSELs then showed promise for high efficiency and reliability. R&D funding increased sharply byindustry and government. The use of such thin active regions in VCSELs required another innovation:
having both mirror reflectivities well above 99%. Such mirrors comprised GaAs/AlAs layers grown by
molecular beam epitaxy. To activate the VCSELs, electrical current was injected into a top gold contact,
through the top mirror, into the active p-n junction, and through the bottom mirror into the substrate.
To overcome electrical resistance at the GaAs/AlAs interfaces, graded superlattices were used. The
features described here were mostly new at the time, and are still used most commercial VCSELs today.
Factors leading to this transformative event in VCSEL development will be described.
18:10 AWS8 (Invited) – "25 Years of VCSEL Research and Development at Ulm University and Philips
Photonics"
Karl J. Ebeling
Univ. of Ulm, Germany
Ulm University appeared in the semiconductor laser arena in the nineties of last century demonstrating
efficient vertical-cavity surface-emitting laser diodes (VCSELs) and early 10 Gbit/s optical datatransmission with these devices. The University start-up U-L-M Photonics founded in 2000 and now
part of Philips has boosted VCSEL development at Ulm by meanwhile producing some 100 million
high-performance VCSELs per year. The privilege of hosting the most memorable ISLC 2002 held at
Garmisch, South Germany, has inspired various important hot-topic VCSEL research activities at the
University and Philips Photonics like for example extended single-mode operation or mass fabricationof polarization-stable devices. From an application point of view we have focused our efforts to explore
VCSELs and arrays for high-speed data communication and routing, surface sensing in computer mice,oxygen absorption spectroscopy, miniaturized Cs-based atomic clocks, distance measurements insmartphones, or materials processing using high power devices. We expect that in the future a novel
mass market for VCSELs will arise in the context of 3-D imaging and 3-D video where brilliant highpower narrow-band VCSEL arrays will provide an almost ideal light source for time-of-flight scene
illumination. Some topics will be highlighted in more detail.

18:40-19:00 Break
19:00-

Welcome Reception (Zuiten (West) room)19