Free-Space Laser Communications: Principles and Advances (Optical and Fiber Communications Reports)

427 Pages·2007·20.58 MB·English

by  Arun Majumdar

OPTICAL AND FIBER
COMMUNICATIONS REPORTS
EditorialBoard: A.Bjarklev,Lyngby
D.Chowdhury,Coming
A.Majumdar,Agoura Hills
M.Nakasawa,Sendai-shi
CG.Someda,Padova
H.-G.Weber,Berlin
OPTICAL AND FIBER
COMMUNICATIONS REPORTS
The OpticalandFiberCommunications Reports(OFCR)bookseriesprovidesasur
veyof selectedtopics attheforefront of research. Eachbookisatopical collection of
contributionsfrom leading research scientists that givesan up-to-date and broad
spectrumoverview ofvarioussubjects.
The maintopics inthisexpandingfieldwillcoverforexample:
• specialtyfibers(periodic fibers,holeyfibers,erbium-dopedfibers)
• broadbandlasers
• optical switching(MEMSor others)
• polarizationandchromaticmodedispersionand compensation
• long-haul transmission
• optical networks (LAN,MAN, WAN)
• protectionand restoration
• furthertopicsofcontemporaryinterest.
Includingbothgeneral informationandahighlytechnical presentationof theresults,
thisseriessatisfiestheneedsof expertsaswellasgraduatesand researchers startingin
thefield.Booksinthis series establishthemselvesas comprehensive guidesand ref
erencetextsfollowingtheimpressiveevolutionofthisareaofscienceandtechnology.
The editors encourage prospective authors to correspond with them in advance of
submitting a manuscript. Submission of manuscripts should be made to one of the
editors.Seealso http://springeronline.comlseries/481O.
EditorialBoard MasatakaNakasawa
Laboratoryof Ultrahigh-speedOptical
Anders Bjarklev Communication
COM,TechnicalUniversity ofDenmark Research Instituteof Electrical
DTUBuilding345V Communication
2800Ksg.Lyngby,Denmark TohokuUniversity
Email:[email protected] 2-1-1Katahira,Aoba-ku
Sendai-shi 980-8577,Japan
DipakChowdhury
Email:[email protected]
CorningInc.
SP-TD-01-2 Carlo G.Someda
Corning,NY 14831,USA Dfil-UniversitadiPadova
Email:[email protected] ViaGradenigo6/A
35131Padova,Italy
Arun K.Majumdar
Email:[email protected]
LCResearch, Inc.
30402Rainbow ViewDrive Hans-GeorgWeber
Agoura Hills,CA91301 Heinrich-HertzInstitut
Email:[email protected] Einsteinufer 37
10587Berlin,Germany
Email:[email protected]
Arun K. Majumdar Jennifer C. Ricklin
Free-Space Laser
Communications
Principles and Advances
~
Springer
ArunK.Majumdar JenniferC.Ricklin
LCResearch,Inc. AMSRL-CI-CN
30402RainbowView Drive 2800PowderMillRd.
AgouraHills,CA91301 Adelphi,MD20783
[email protected] [email protected]
ISBN-13:978-0-387-28652-5 e-ISBN-13:978-0-387-28677-8
LibraryofCongressControlNumber: 2006939943
©2008SpringerScience+BusinessMedia, LLC
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Printedonacid-free paper.
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Preface
Free-space laser communications, also referred to as optical communica
tions, is a popular subject in today's technological marketplace. A number
of conferences on this subject havebeen organized by professional societies
such as SPIE (the International Society of Photo Optical and Instrumenta
tion Engineering),OSA (Optical Societyof America), and IEEE(Instituteof
Electrical and Electronics Engineers).The evolving technology of free-space
laser communications is emerging as an appealing alternative to RF com
munications for links between satellites, as wellas a promising addition to
terrestrial applicationssuch as video or computerlinkups between buildings.
There isa pressing need for more information on lasercommunicationsthat
iscomprehensive enough to provide in-depth knowledge of free-space com
munications, and that can satisfy the current demands of the research and
commercial needs.
This book has been designed to provide a comprehensive, unified tutorial
to further understandingof the fundamental techniques for laser communi
cations through the earth's atmosphere.The driving force behind free-space
laser communications is the continuous demand for higher bandwidth to
deliver high-capacity voice, data, and images to the customer. Free-space
propagation distances include ranges that encompass a fewmillimeters (for
example between optical interconnects in a computer using photonics to
replacemetal interconnects), a fewmeters (such asindoorcommunications),
afewkilometers(betweenbuildings,campuses,and hospitals),and evenupto
thousands of kilometers(such as from an aircraft or satellite to the ground).
Although the concept of free-space laser communications systems has been
around as long as the laser itself, it has not been as widelyimplemented in
fieldedsystemsasone might expect. There havebeen severalreasons forthis,
theprincipalone beingthe lack of ademonstratable needforextremelyhigh
bandwidth wirelesssystems, and the cost, complexity, and reliability of the
technology involved.There havealso been complications with several of the
attemptstofieldlarge-scaleoperational systems.But with the unprecedented
growthof theinternet,multimedia,and related dataservicesand imagetrans
fer,there has beena tremendouslygrowingappetiteforimmediatelyavailable
information at high bandwidth.This has givenfree-space laser communica
tions a unique nicheinthe communicationsmarket.
v
VI Preface
The need for bandwidth for both commercial and military applications is
growing faster than the ability of the local infrastructure to provide them,
and also faster than the rate at which the infrastructure can be augmented.
Technologydevelopmentintheareasof highermodulationcapabilityof laser
sources,fastand sensitivedetectors, and opticalcomponentssuchasDWDM
(Dense Wavelength Division Multiplexing) and optical amplifiers, all have
helped to achieve higher bandwidth. However,at optical wavelengths, the
interaction of electromagnetic waveswith the atmosphere is much stronger
than that at microwave frequencies, and hence weather conditions such as
turbulence and foglimitthe performanceof optical links.
This book provides a comprehensive overview for readers who require
information about the basics of free-space lasercommunications, as wellas
up-to-dateadvanced knowledge of the state-of-the-arttechnologiesavailable
today. Wehave tried to make this book as useful as possible as a resource
forengineers,scientists,researchers,and studentsinterested inunderstanding
and designing laser communication systems for atmospheric channels. The
reader willfurther benefit from the knowledge of how adaptive optics and
related technologies such as MEMS (Micro-Electro-Mechanical Systems)
can be integrated into free-space laser communications. There iscontinuity
betweenchapters so that the information and learning fromanyonechapter
isconnected to that of the otherchapters.
Chapter 1isan introduction to atmosphericlasercommunicationand dis
cussestheoveralllasercommunicationsarchitecture. Thischapterservesasa
general background fortheconcepts presented insubsequentchapters.
Chapter2describes the impact that atmosphericeffectshaveon lasercom
munication systems.This chapter describes the physical processes underly
ing optical extinction and optical turbulence-induced signal losses. Recent
advances in the modeling of optical scintillation under weak-to-strong fluc
tuations associated with both terrestrial linksand satellite/ground links have
beenaddressed.This and other information giveninthis chapterenablecal
culationoftheanticipated systemperformanceovera widerange of channel
characteristicsforground-to-ground,ground-to-air/air-to-ground,and satel
liteuplink/downlink optical communicationscenarios.
Chapter 3 provides a theoretical treatment and analysis of the perform
ance of a free-space laser communication system under a givencommuni
cation format scheme.This chapter develops a communication link budget
model relating the atmospheric channel effectsand the main parameters of
the transmitter and receiverstations. Numerous examples are givenfor spe
cificsystemparametersinordertodesignaspecificsystem.Variousscenarios
of practical importanceare described:horizontal (terrestrial) links,and slant
paths including downlink (satellite-to-ground) and uplink (ground-to-satel
lite).Thissystemperformanceanalysiswillbeusefulfordesignersinoptimiz
ingthe optical station main parameters inorder to establish a data link with
adequate performanceundervarious atmosphericconditions.
Preface Vll
Chapter4providesan overviewof state-of-the-art,aswellasfuture optical
transmitterand receiver,designsthatareparticularlywellsuited forfree-space
lasercommunications. Emphasis isplaced on high-performance photon-effi
cient systemsand technologies suitable foroperation in both deep space and
terrestrial optical links.This chapter focuses on practical design options for
the transmitter and receiver blocks. Practical tradeoffs and implementation
issuesthat arise from using various technologies are presented,and the inter
play between modulation format, transmitter waveform, and receiverdesign
are discussed.
Wave-front distortions of optical waves can be mitigated, in principle,
with adaptive optics. Chapter 5 discusses an adaptive optics approach that
hassignificantadvantagesforfree-spacelasercommunicationterminals. This
technique does not require wave-front measurements, which are difficult to
obtainunderthestrongscintillationconditionstypical formany communica
tion scenarios.Itisbased on thedirect optimizationof aperformancequality
metric, e.g., the communication signal strength. An experimental adaptive
optics systemisalso described.
Chapter 6 provides a broadband optical wirelesssolution for closing the
"lastmile"connectivitygap throughoutmetropolitannetworks. This chapter
discussesvarious network architecturesand the usage of "optical repeaters."
Point-to-pointand point-to-multipointsolutionsareexplained forconstruct
ingdifferent network architectures.Terrestrialapplicationsforshortand long
ranges,as wellasspace applications, are described. Importantdesigncriteria
forconnectingthe userto the "backbone"byfreespace optics techniquesare
explained.
Error-controlcodescan helptomitigateturbulence-induced signalfading in
lasercommunicationsthrough atmospheric turbulence. Chapter 7providesan
in-depth treatment of thiscriticalsubjectthrough the useof techniques based
on the statistical properties of turbulence-induced signalintensity fading as a
function of bothtemporal and spatialcoordinates.Anoptimal maximum-like
lihood detection schemeisdescribed forcorrelated spatial-diversityreception.
Thischapteralsodescribesan experimentaldemonstrationof theeffectiveness
of twotemporal domain techniquesina terrestrial linkusingon-offkeying.
The three remaining chapters cover the recent development of longer
wavelength free-space laser communications. A longer wavelength source
can provide significantly improved transmission through the atmosphere,
as compared to shorter wavelengths. Chapter 8 discusses optical parametric
oscillation devices used for mid-IR (MWIR) data communication through
lowvisibilityconditions.This chapter also describes the design of a MWIR
transceiver that provides high peak power and short pulses for the Multiple
Integrated Laser EngagementSystem (MILES) program.
Chapter 9 discusses the high-speed modulation properties of a quantum
cascade laser (QCL) suitable for free-space laser communications. A com
parison of experiments between a QCL and a near-infrared laser-based link
VIII Preface
in controlled low-visibilityexperiments isdiscussed.A recent application of
a QCL-based link used for transmission of satellite TV data streams is also
presentedinthischapter.
Chapter 10 discusses technology for all-weather long-wavelength infrared
(LWIR) free-space optical communications. Superior transmission through
atmosphericphenomenasuchasfog,clouds,and smoke,coupledwithimprove
ments in LWIR laser and modulator design, makes possible reliable optical
replacements forradio and microwavecommunication linksformanyapplica
tions.This chaptersummarizes thecomponentsand techniquesdeveloped for
high-speed,full-duplexall-weatherinfraredcommunicationssystems.
Weexpress our sincere appreciation to Dr. Hans I Koelsch, the Springer
Editorial Director for Physics,for his encouragement and interest from the
very start of this project. Wealso thank all of the contributors, as wellas
Ms.Virginia Lipsey,Associate Editorfor Physics,and Ms.Vasudha Gandhi,
Editorial Assistant, for their continuous help throughout the preparation of
this book. A.K. Majumdar wishesto thank hisdaughterSharmistha for her
help in checking the texts of his sections, his wifeGargi for her encourage
ment and support,and alsohisfelinefriends,Rockyand Sasha, whoprovided
unconditionalcompanionshipfortheentire duration of hiswork incomplet
ing this project. He also wishes to pay tribute to the memory of his brother,
Dr. Nirmal Majumdarof London,whowasaconstantsource of inspiration
throughouthiswriting ofthisbook.IC. Ricklin thanksherhusband Mikhail
forhissupportandencouragement,aswellasthegrayfamilycatwhokeptthe
monitor'smouse icon undercontinuousstrongobservationand control.
Arun K.Majumdar
Agoura Hills,California
JenniferC.Ricklin
Laurel, Maryland
Contributors
Dr. UHaBirnbacher Dr. Stephen Hammel
DepartmentofCommunications AtmosphericPropagation Branch
and WavePropagation 2558Space and Naval Warfare
GrazTechnical University Systems Center
A-8010Graz,Inffeldgasse 12,Austria San Diego,CA 92152
[email protected] [email protected]
43-3I6-873-7442 [phone]
Dr.David Caplan Dr.Donald P.Hutchinson
MIT Lincoln Laboratory EngineeringScienceand Technology
Optical Communications Division
Technology Oak Ridge National Laboratory
244Wood St., Mail StopC-245, Bethel VaHey Road, Oak Ridge,
Lexington, MA 02420 TN 37831
[email protected] [email protected]
[phone];CeH:[phone] [phone];CeH:(865)
382-8155
Dr. Frank D.Eaton
AFRLlDESA, Air Force Research Prof.Joseph M. Kahn
Laboratory DepartmentofElectrical
3550Aberdeen Ave.SE,Kirtland Engineering
AFB,NM 87117 Stanford University
[email protected] 372Packard Building, 350Serra
[phone] MaH,Stanford,CA 94305-9515
[email protected]
Dr.MichaelGebhart [phone]
DepartmentofCommunications
and WavePropagation Dr.SvetlanaL. Lachinova
GrazTechnical University Institute forSystems Research
A-8010Graz,Inffeidgasse 12,Austria Universityof Maryland
[email protected] College Park,MD 20742
43-3I6-873-7442 [email protected]
IX