Table Of ContentTopics in Applied Physics
Volume 89
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Irina T. Sorokina KonstantinL . Vodopyanov
(Eds.)
Solid-State Mid-Infrared
Laser Sources
With 263 Figures and 36 Tables
~ Springer
Irina T. Sorokina Dr. Konstantin L. Vodopyanov
Dr.
Photonics Institute Ginzton Laboratory
Technical University of Vienna Stanford University
Gusshausstr. z71387 Stanford, CA 943o5-4o88
lO4O Vienna USA
Austria
vodopyan@stanford, edu
sorokina~tuwien, ac. at
Library of Congress Cataloging in Publication Data
Solid-state mid-infrared laser sources/Irina T. Sorokina, Konstantin L. Vodopyanov (eds.). p. cm. - (Topics in
applied physics, ISSN o3o3-4z16; v. 89) Includes bilbiographical references and index. ISBN 3-54o-o0621-4 (alk.
paper) a. Solid-state lasers, z. Laser materials. I. Sorokina, Irina T., 1963- II. Vodopyanov, Konstantin L., 1953-
IIl. Series
Physics and Astronomy Classification Scheme (PACS):
4z.72.Ai, 42.55.-f, 42.62.-b, 42.65.Ky, 42.65.Yj
ISSN print edition: o3o3-4216
ISSN electronic edition: 1437-o859
ISBN 3-54o-oo621-4 Springer-Verlag Berlin Heidelberg New York
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Preface
According to the Encyclopaedia Britannica, the "middle infrared" region cov-
ers the portion of the electromagnetic spectrum between 400 and 4000 wave
numbers, which corresponds to the wavelength range 2.5-25 gin. This range
is of particular interest for many applications, especially for spectroscopy,
since the electromagnetic frequencies involved coincide with frequencies of
the internal vibrational motion of most molecules (the "molecular finger-
print" region). In our book, we define the "mid-infrared" more loosely to
cover a slightly broader range starting from ~ 2 gm wavelength. On the
longer wavelength end, we even included two chapters on terahertz wave
generation, reflecting the fact that as terahertz waves are pushed further to
higher frequencies, they converge with the long-wavelength infrared domain
(for example, a frequency of 10 THz corresponds to a wavelength of 30 ~tm).
The development of solid-state laser sources in the mid-infrared opens un-
precedented possibilities in spectroscopy~ as compared to traditionally used
Fourier-transform spectrometers. The obvious advantages of lasers are direc-
tionality, coherence, narrow linewidth or small pulse duration, and high spec-
tral brightness. Compact and efficient nfid-infrared laser sources can serve
advantageously for remote light detection and ranging (LIDAR) (down to
parts-per-billion in volume) of many trace gases and vapors that are impor-
tant in pollution detection, and atmospheric chemistry. Other opportunities
for fixed-wavelength and tunable mid-infrared laser sources include medical
applications (e.g. microsurgery, dentistry, keratectomy or non-invasive diag-
nostics by means of breath analysis), ultrasensitive detection of drugs and
explosives (down to one part per trillion) using photoacoustie or cavity ring-
down spectroscopy, and free-space communications.
Near-infrared laser sources (0.8 1.6 p.m) achieved significant market pen-
etration during the past decade, but the technology for mid-infrared lasers,
especially those which operate at room temperature, needed considerable
improvement, despite the fact that mid-infrared lasers have existed since the
beginning of the laser era. In recent years, however, scientific research in the
field of generation of coherent radiation in the mid-infrared experienced a rev-
olution. On the one hand, it was largely connected with the rapid progress
in semiconductor technology, and on the other, with exploiting new physi-
cal ideas and new material development. The most spectacular example is
VI Preface
the quantum cascade laser, pioneered by Lucent Technologies in 1994. An-
other example is optical parametric oscillators that can operate with > 10 W
average power or have up to 95 % quantum conversion efficiency. Periodi-
cally poled ferroelectric materials revolutionized nonlinear optics and made
it possible to create new, highly efficient tunable devices. We have also seen
a gigantic leap forward in fiber laser technology with infrared fiber lasers
delivering multi-watt output power.
Quite different scientific domains (semiconductor physics, solid state
physics, material science, nonlinear optics, laser physics, quantum optics)
are converging to investigate new nfid-infrared sources. This book assembles
the results from different scientific communities focused on achieving the goal
of creating an efficient and inexpensive solid-state mid-infrared laser source.
The first two chapters concentrate on semiconductor lasers: Andrd doullid,
Philippe Christol, Alexei Baranov and Aurore Vicet describe the latest ad-
vances in the 2 5 gm heterojunction laser diodes based on III-V as well as
IV VI semiconductor structures. Daniel Hofstetter and Jdrdrne Faist review
results on distributed feedback quantum cascade lasers in the wavelength
range around 5 p.m and around 10 ~n and discuss their applications in spec-
troscopy and free space communications.
The chapter by Cornelia Fischer and Markus Sigrist addresses the nonlin-
ear optical technique known as difference frequency generation and gives some
examples of spectroscopic applications. The next two chapters describe in de-
tail the underlying principles and advances in nfid-infrared optical parametric
oscillators operating in the pulsed mode (chapter by Konstantin Vodopyanov)
and in the continuous-wave and synchronously pumped modes (chapter by
Majid Ebrahimzadeh ).
The current state-of-the-art in mid-infrared fiber lasers is reviewed by
Markus Pollnau and Stuart Jackson. The authors describe lasers at transi-
tions ranging from 1.9 to 4 gm in the rare-earth ions Tm 3+, Ho 3+, and Er 3+,
their population mechanisms, and their power-scaling methods. The chap-
ter by Irina Sorokina surveys ion-doped crystalline lasers operating in the
mid-infrared between 2 and 5 microns. Her review includes rare-earth- and
transition-metal-based laser crystals, as well as the color-center lasers, with
special emphasis on compact room-temperature tunable sources based on vi-
bronic lasers. The chapter by Tasoltan Basiev, Vyacheslav Osiko, Alexander
Prokhorov and Evgeny Dianov presents the latest achievements in the field
of Raman lasers based on a variety of crystals and optical fibers.
The next two chapters describe terahertz (THz) coherent sources: Kodo
Kawase, Jun-ichi Shikata and Hiromasa Ito review methods of generating
widely tunable THz waves using nonlinear optical techniques: parametric
generation and difference frequency generation. In the chapter by Hiroshi
Takahashi, Hidetoshi Murakami, Hideyuki Ohtake, and Nobuhiko Sarukura,
the authors describe generation of THz radiation using ultrafast lasers and
semiconductor-based materials. The techniques include semiconductor opti-
Preface VII
cal switches, optical rectification and difference frequency generation, as well
as generation of THz waves based on intersubband transitions in semicon-
ductor quantum wells.
The last two chapters discuss applications of mi.d-infrared lasers: Frank
Tittel, Dirk Richter and Alan Fried present a large number of spectroscopic
laser techniques for sensitive, selective, and quantitative trace gas detection
with tunable narrow-linewidth mid-infrared coherent sources. The chapter
by Benedikt Jean and Thomas Bende reviews applications of mid-infrared
lasers in medicine. These applications exploit strong laser light absorption
in tissue due to the presence of natural chromophores and include: gynae-
cology, otorhinolaryngology, neurosurgery, dermatology, urology, dentistry,
ophthalmology, cardio vascular surgery and angioplasty.
We believe theft this book will be useful for academics, researchers and
engineers in various disciplines who require a broad introduction to the sub-
ject and would like to learn more about the state-of-the-art and upcoming
trends in mid-infrared coherent source development. Finally, we would like
to thank all contributors who have found the time, energy and enthusiasm
to write these chapters.
Palo Alto Konstantin Vodopyanov
Vienna Irina Sorokina
May 2003
Contents
Mid-Infrared 2-5 pxm Heterojunction Laser Diodes
And% JoulliS, Philippe Christol, Alexei N. Baranov and Aurore Vicet ... 1
1. Introduction ........................................................ 1
2. Historical ........................................................... 3
3. State of the Art ..................................................... 5
3.1. Typical Heterojunetion Laser Structure ....................... 5
3.2. Maximum Temperature of Operation .......................... 9
3.3. Maximum Operating Temperature
in the 2-5 ~tm Wavelength Domain ........................... 11
4. Antimonide Quantum Well Laser Diodes
for the 2-3 p.m Spectral Range ..................................... 13
4.1. Strained GaInAsSb Alloys and Quantmn Wells ............... 14
4.2. Fabrication of Antimonide Quantum Well Laser Diodes ...... 20
4.3. Antimonide QW Laser Diodes
for the 2.0-2.3 ~tm Spectral Range ............................ 23
4.4. GaInAsSb QW Laser Diodes Emitting beyond 2.3 bm~ ........ 28
4.5. Characterization of Antimonide-Based Laser Diodes
Dedicated to Gas Detection .................................. 33
5. 3 5 bun Interband Type-II Laser Diodes ............................ 40
5.1. InAsSb/InAs Type-II Multi-qantum Well Laser .............. 41
5.2. InAs/GaInSb Type-III "W" Laser ............................ 45
6. Conclusion ........................................................ 48
References ............................................................. 50
High Performance Quantum Cascade Lasers
and Their Applications
Daniel Hofstetter and J6r6me Faist .................................... 61
1. Introduction ....................................................... 61
2. Gain Region Designs ............................................... 64
2.1. Basic Working Principles of QC Lasers ....................... 64
2.2. Three Quantum Well Gain Region ........................... 66
X Contents
2.3. Gain Region with Double-phonon Resonance ................. 66
3. Fabrication Technologies ........................................... 68
3.1. Surface Grating with Lateral Current h@ction ............... 68
3.2. Lasers with InP Regrowth ................................... 70
3.3. Junction Down Mounting .................................... 70
4. Measurement Results .............................................. 71
4.1. Measurement Setup .......................................... 71
4.2. DFB Laser with Lateral Current Injection
in the 5 lain and 10 p.m Band ................................. 72
4.3. DFB Lasers with InP Over-Grown Grating ................... 80
4.4. High Power Junction Down Mounted Lasers .................. 82
4.5. Room Temperature Continuous Wave Operation
of QC Lasers ................................................. 84
5. Applications ....................................................... 86
5.1. Photo-Acoustic Spectroscopy ................................. 86
5.2. Optical Data Link Using a QC Laser ......................... 89
6. Conclusions ........................................................ 92
References ............................................................. 92
Mid-IR Difference Frequency Generation
Cornelia Fischer and Markus W. Sigrist ................................ 97
1. Introduction to Tunable Mid-IR Laser Sources ..................... 97
2. Basic Principles of Nonlinear Optics
and Difference Frequency Generation ............................. 100
2.1. Frequency Conversion Processes ............................. 100
2.2. Nonlinear Optical Coefficient ............................... 103
2.3. Phase Matching ............................................. 105
3. Material Considerations .......................................... 118
3.1. Selection of Nonlinear Medium .............................. 119
3.2. Pump and Signal Laser Sources
for Difference Frequency Generation ........................ 121
4. Difference Frequency Laser Systems Reported in the Literature ... 122
4.1. Difference Frequency Laser Sources ......................... 122
4.2. Difference Frequency Laser Sources Applied in Gas Sensing . 122
5. Detailed Description of a Mid-IR DFG Laser Source .............. 125
5.1. Experimental Set-Up and System Performance .............. 125
5.2. Nd:YAG Pump Laser ....................................... 126
5.3. External Cavity Diode Laser ................................ 127
5.4. Tuning with Periodically Poled LiNbO3 ..................... 128
5.5. Detection Schemes .......................................... 129
6. Applications of Mid-IR Difference Frequency Laser Systems
in Gas Sensing ................................................... 131
6.1. General Considerations ..................................... 131
Contents XI
6.2. Examples of Gas Spectroscopy Performed
with Our DFG Laser Source ................................ 132
7. Conclusions and Outlook ......................................... 135
References ............................................................ 136
Pulsed Mid-IR Optical Parametric Oscillators
Konstantin Vodopyanov .............................................. 141
1. Introduction ...................................................... 141
2. Principle of OPO Operation ...................................... 142
3. OPOs in the 2 5 p.m Range ....................................... 145
3.1. Comparison of NLO Materials .............................. 145
3.2. OPOs Based on PP LN .................................... 146
3.3. OeOs Based on PP KTP and PP RTA ..................... 149
3.4. OPOs Based on PP KTA ................................... 151
3.5. OPOs Using Conventional Phase-matching in Oxides ........ 151
4. OPOs in the 4 201xm Range ...................................... 153
4.1. Comparison of NLO Materials Suitable for ~ > 5~tm ........ 153
4.2. OPOs Based on AGS and AGSe ............................ 154
4.3. OPOs Based on ZGP ....................................... 155
4.4. OPOs Based on Other Crystals ............................. 160
5. Traveling-Wave Optical Parametric Generators (OPGs) ........... 161
5.1. OPGs Based on PP LN ..................................... 162
5.2. OPGs Based on ZGP ....................................... 163
5.3. OPGs Based on GaSe ....................................... 164
5.4. OPGs Based on CGA ....................................... 165
6. Narrow-Linewidth OPOs ......................................... 165
6.1. Using Intracavity Spectral-Narrowing Elements ............. 166
6.2. Narrow-Linewidth Optical Parametric Generator Optical
Parametric Amplifier (OPG OPA) Systems ................. 167
6.3. OPOs with Injection Seeding ................................ 168
6.4. Using a Doubly Resonant Cavity ............................ 169
7. Emerging Nonlinear Optical Materials for Mid-IR Applications ... 171
8. Summary and Concluding Remarks ............................... 173
References ............................................................ 174
Mid-Infrared Ultrafast
and Continuous-Wave Optical Parametric Oscillators
Majid Ebrahimzadeh ................................................. 179
1. Introduction ...................................................... 179
2. Optical Parametric Process ....................................... 181
2.1. Optical Parametric Gain .................................... 183
2.2. Optical Parametric Amplification ........................... 184
