The light fantastic : a modern introduction to classical and quantum optics

653 Pages·2008·8.296 MB·English

by  I R Kenyon

THE LIGHT FANTASTIC
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The Light Fantastic
A Modern Introduction to Classical
and Quantum Optics
I. R. Kenyon
SchoolofPhysicsandAstronomy
UniversityofBirmingham
1
3
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Preface
This book deals primarily with the properties and uses of electromag-
neticwavesandphotonsofvisiblelight. Otherregionsoftheelectromag-
netic spectrum are only treated where appropriate: for example there
iscoverageofopticalfibre communicationusing nearinfraredradiation.
Modern quantum theory originated in the observations of the quantum
behaviour of electromagnetic radiation, and now, a century later the
quantumbehaviouroflightofferstantalizing possibilities forcomputing
and encryption. During that period a deeper understanding of electro-
magneticradiationintermsofwavesandphotonshasmadepossiblethe
inventionoflasers,opticalfibre communication,space-basedtelescopes,
the world wide web and digital cameras. The optoelectronics industry,
undreamt of even forty years ago, has grown to be a major employer
of scientists and engineers. Even crude measures, such as the hundred
million solid state lasers made annually, the millions of kilometres of
optical fibre installed, and the widespread availability of megapixeldig-
ital cameras and of DVDs give a sense of this industry’s economic and
cultural impact. Studies of the subtle features of quantum theory, such
asentangledstates,havebeenfacilitatedbyresearchtoolsdependenton
the technological advances in optoelectronics, which illustrates the tru-
ism that technology and pure science go forwardhand-in-hand. Clearly
there is a necessity for a wide range of scientists and technologists to
possess an up-to-date understanding of waves and photons so that they
can make use of the theoretical, experimental and technological tools
now available. The main objective of this text is to provide that basic
understanding, which will be important if the reader is to follow future
developments in this rapidly expanding field.
The text is designed to be comprehensive and up-to-date so that stu-
dents at universities and colleges of technology should find this volume
useful throughout their degree programme. Following an introductory
chapter in which basic concepts and facts are presented, the book is
divided into three sections: the first section (Chapters 2–4) covers ray
optics, the second section (Chapters 5–11) wave optics, and the final
section (Chapters 12–18)quantum optics.
Huygen’s principle is used to derive laws of propagation at interfaces
in Chapter 2. On this basis the geometric optics of mirrors and lenses
vi Preface
is treated in Chapter 3. Then the principles and design of optical in-
strumentsincludingmicroscopes,telescopesandcamerasareoutlinedin
Chapter 4. Aberrations and the simpler techniques for reducing them
to tolerable levels are also described in Chapters 3 and 4.
ThesectiononwaveopticsstartsinChapter5withthe superposition
rule for electromagnetic wavesand its applicationto interference effects
suchasthoseseeninYoung’scrucialtwoslitexperimentandtheMichel-
son interferometer. Coherence and the relation to atomic wavepackets
arebothintroducedinthesesimpleexamples. Diffractioneffectsarecon-
sidered in Chapter 6. Fourier transforms, of which diffraction patterns
are anexample, are treated formally in Chapter 7. This allowsthe con-
nection between Michelson interferograms and the source spectrum to
be exploited in extracting spectra with standard infraredFourier trans-
form (FTIR) spectrometers. Chapter 8 pulls together themes in optical
instrument design in describing the design of optical mirror telescopes
and radio telescopes, and goes on to compare their performance. Elec-
tromagnetic wave theory rests on Maxwell’s equations and Poynting’s
theorem for the energy in electromagnetic waves. The electromagnetic
wave equation and the laws of propogation of light at interfaces (Fres-
nel’s laws) are derived directly from classical electromagnetic theory in
Chapter9. Theuseofevanescentwavesinopticalfibresandotherappli-
cationsaredescribed. Chapter10carriesthe descriptionofpolarization
forward to include circular polarization which is revealingly the polar-
ization state of individual photons. Electromagnetic interactions with
matter in semiclassical terms are discussed in Chapter 11: dispersion,
absorption and scattering are described and shown to be related. This
completestwosectionsdevotedtothepurelyclassicalbehaviouroflight.
An account of the fundamental experiments that underpin the quan-
tum theory of electromagnetic radiation in Chapter 12 opens the sec-
tion on quantum optics. In Chapter 13 the dual wave–particle nature
of electromagnetic radiation and the Heisenberg uncertainty principle
are examined at length. The principles underlying laser operation, as
well as gas, solid state and semiconductor lasers, and their applications
aretreatedinChapter14. Detectorsofradiationinthe visible andnear
infraredaredescribedinChapter15: theseincludetheCCDandCMOS
arraysusedindigitalcameras. Opticalfibre basedcommunicationprin-
ciples,devicesandsystems,aswellasopticalfibre sensorsaredescribed
inChapter16. Chapter17introducesthesemiclassicalcalculationofde-
cay rates and the behaviour of atoms in the resonantand near resonant
laserbeams. Effectsincludingelectromagneticallyinducedtransparency
and slow light are introduced. After this the developments leading to
the fabrication of optical clocks are described. Chapter 18 starts by
introducing the formal treatment of electromagnetic fields as quantum
mechanical operators (second quantization). This is followed by a de-
scriptionofthe study of correlationsbetweenphotons, firstobservedby
HanburyBrownandTwiss. Thenthetheoryandexperimentalmethods
vii
for generating entangled photons are described; experimental studies of
two photon correlations in interferometers showing delayed choice and
quantum erasure close the chapter.
Thetexthasbeendesignedsothatsubsetsofchaptersareself-contained
andwellsuitedtoaccompanyfocusedopticscourses,whilethecomplete
text provides compact coverage for courses that extend through three
orfouryears. Chapters1–4covergeometricoptics;Chapters5–11cover
classicalwaveoptics;andChapters12–18coverquantumoptics,includ-
ing individual chapters on lasers and modern detectors. A suggested
reduced course could include all the chapters and sections listed here:
• Introduction and ray optics: Chapters 1 and 2;
• Lenses without abberations: Sections 3.1 to 3.6.1;
• Optical instruments: Sections 4.1 to 4.5.2, and 4.8;
• Wave optics and interferometers: Sections 5.1 to 5.7.1, and 5.8 to
5.9;
• Diffraction and gratings: Sections 6.1 to 6.9;
• Astronomical telescopes: Sections 8.1 to 8.3;
• ElectromagnetictheoryandFresnel’slaws: Sections9.1and9.4to
9.6, and 9.8 to 9.8.1;
• Polarization phenomena: Sections 10.1 to 10.4, and 10.5, and
10.5.2 to 10.7.1, and 10.8 to 10.8.3;
• Light in matter: Sections 11.1 to 11.6.2;
• Quantum behaviour of light: Chapter 12; Sections 13.1 to 13.5.2,
and 13.11 to 13.13;
• Lasers and detectors: Sections 14.1 to 14.4, and 14.4.3 to 14.6;
Sections 15.1 to 15.3.1, and 15.7 to 15.9;
• Optical fibre communication: Sections 16.1 to 16.2, and 16.4 to
16.6, and 16.9 to 16.10.1,and 16.13 to 16.14.
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Acknowledgements
IwouldliketothanktwoHeadsoftheSchoolofPhysicsandAstronomy
atBirminghamUniversity,ProfessorsJohnNelsonandMikeGunn, and
also Professor Peter Watkins, Head of the Elementary Particle Physics
Groupat Birmingham,for their support and encouragementduring the
more than four years’ preparation of this textbook. Dr Sonke Adlung,
the senior science editor at Oxford University Press, has always been
unfailingly helpful and courteous in dealing with the many aspects of
the preparation,and my thanks go to him for making my path easier. I
am also grateful to Jonathan Rubery, Chloe Plummer and Lynsey Liv-
ingstonat Oxford University Press for the smooth management of copy
editing, layout, production and publicity.
Manycolleagueshavebeenmorethangenerousinfindingtimeinbusy
lives to read and comment on material for which they have a particu-
lar interest and expertise. First I want to thank Professor Ken Strain
of the Institute for GravitationalResearch, GlasgowUniversity and the
GEO600 team for reading and commenting on the material on gravi-
tational wave detection and Professor Peter Tuthill of the Astronomy
Department, University of Sydney, for reading and commenting on the
sectionsconcerningaperturesynthesiswithtelescopes. Iamindebtedto
ProfessorChrisHaniffoftheAstrophysicsGroupattheCavendishLabo-
ratory,CambridgeUniversitywhoreadthroughthematerialonmodern
interferometry with telescopes and aperture synthesis, and made exten-
sive valuable comments. Also I wish to thank Professor Helen Gleeson
of the University of Manchester for reading and commenting on the po-
larization chapter, particularly the section on liquid crystals. Dr Peter
Norreys,GroupLeaderatthe CentralLaserFacility,RutherfordApple-
tonLaboratory,helped me by checkingthe materialrelatingto extreme
energy lasers. I am indebted to Dr Peter Pool of EEV CCD Sensors
who patiently answered my many questions about CCD stucture and
readout. Ian Bennion, Professor of Optoelectronics at the University
of Aston, was kind enough to look over the material on optical fibres
and made some very useful suggestions for improvement; I extend my
thanks to him. I am particularly grateful to Lene Hau, Mallinckrodt
Professor of Physics and Applied Physics at Harvard University, who
made comments on the sections concerning electromagneticallyinduced
transparency, and to Professor David Wineland of the Time and Fre-