LASER FUNDAMENTALS
`
`SECOND EDITION
`
`WI LL IAM T. SI LFVAST
`
`School of Upfits r CHE-DL
`Lhivmfiily of Centrd Florida
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`CAMBRIDGE
`UNIVERSITY PRESS
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`(cid:36)(cid:54)(cid:48)(cid:47) (cid:20)(cid:20)(cid:19)(cid:25)
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`ASML 1106
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`1
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`PUBLISHED B1" THE Fl 5‘|"N']fl3.|'1'l'E OF THE. UNIVERSITY I]-F Ch.hlBll]II3E
`The P‘i1 lhilrilg. 'I'rI.|Ipi|gI:n SII'aet.('_‘:n|J|ifi;e. lltiud Iiingclnln
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`ISBN l.'I—52l—333-15-0
`1. Laser:
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`'[?aI5'.F5.S52
`ISII_"H5"6—d:QI
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`ISBN I] SEIIEIBI1-5|] I1:lII:|l:I
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`‘K113055352
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`2
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`

`
`Contents
`
`Prefix: Io Ike Second‘ .E'n'i£icm
`
`Prefixes so the Firm‘ Edition
`
`Acknawfetflgnlwcnis
`
`I
`
`INTIIDDUETIDN
`CW'ER'|I'IE|I'
`Illtrolluclion
`Deliilion of lhe Lme-1'
`
`b1|npl||1"' "I3: 0|’ a Luel-
`Unique
`of a Lmer
`The Laser Spectrum and Wavdungths
`A Brief I-lislory oflbe Laser
`flwI'I"IeI'Ir of III! ll‘-uok
`
`SECTION 1- FUNDAMENTAL WAVE FIIDPERTITES OF LIGHT
`
`Z WAVE NATURE OF LIGHT — THE INTERACTION CIF LIGHT
`‘WITH MATERIALS
`(W'E.ll‘||'IlI|I'
`
`2.1 Maxwell’: Eipntions
`2.1 Ma:n-lull’: Wave Equalione
`Maxwell's ‘Wave Equations for a Vacuum
`Solution ofthe Genera] Wave Equation — Equivalence of Light and
`E c Radiation
`‘WaveVe|o::il].r — Phase and Group Velodljea
`Generalizeii Sn-Iution ofdlewalre Equalion
`Transverse Eleclrollztagoetic ‘Waves and Polarized liglu
`Flow of Elemroinagnetic Energy
`Randiation [mm a Point Source (EIe:t:u:ic Dipole Radiation]
`2.3-
`lute-I-aclion of Eluflrotlagnt-lit Radialioll (light) wih Matter
`Speed of Light in a Medium
`Maxwell's Equaliona in a Me:diu.1n
`Application ol'Ma.uI.reil's Equations lo Dieiecuic Malerials —
`Laser Gain Media
`
`Compie: Index of RcI'Ia.c:Iion — Opljcai Conalanla
`Abaorpljolt and Dispesraion
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`page xix
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`xxi
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`L.n,p.I,_1h;b_1._.__.._
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`CDIITEHTS
`
`Estimating Particle Densities o-fltllatetials for Use in the
`Dispersion Equations
`LI Coherence
`
`Teropotal Coherence
`Spatial Coherence
`REFERENCE
`PI:l]IlI..E.Il'S
`
`SECTION 2. F7l.lHD.AHEH'I'Al. CliJ.AH'I'UM FIIDPEIITIES OF LIEHT
`
`3 PART|.CI.E HAJURE OF LIGHT — DISCRETE ENERGY’ LEVELS
`{|‘I"EI‘I"IE'W
`
`3.] Bohr Theory oltbe Hydrogen Alum
`Historical Development ofihe Concept of Discrete. Energy Levels
`Enesgy I..El|'ElS of the Hydrogen Atom
`Frequency and Wavelczngtf-lr oi Emission lines
`Ionization Energiesand Energy ]_.e1.reh o-flons
`Photons
`
`offittoulir Fsrergy I.e'rels
`3.1 Qualrlum
`Wave Nature otlPanir:les
`
`Heisenberg lJncer1a.inty Principle
`Warre'l'l1eoIy
`Wave Functiorrs
`Quantum States
`The Schrodinger Wave Equation
`Energy and Wave I-"11nr:Iionl'or ll'!.I’:'GtlJtItl.l2l State of the
`Hydrogen Atom
`Excited States of Hyrkogen
`Alloured Ouauturo Numbers for Hydrogen Aiomwave Functions
`3.] Angular Mumeulrli of Alums
`Drbital Angular hloorenturo
`Spin Angulx Momerrurm
`Total Angular Mornenlnrn
`Jul Energr Levels Afioeialerl with Due-Electron Atoms
`Fine S«u1u:ture cl" Spectral Lines
`Pauli Exclusion Principle
`J5 Periodic Table 0|’ the Elements
`
`Quanturo Conditions Associated with Multiple Electrons Auaeheil
`to Nuclei
`
`Shoetlranazl Notation for Electronic Configurations ofAtJon1s Having
`More Than One Electron
`
`3.6 Fnergy Levels 0I‘l't'Itlli-Flleelmu Atoms
`Ene:gy—I..e'I.rel Designation For Multi—Electron Stare:
`Russ.ell—Saunders or L5 Coupling — Notation lorEnergy Levels
`Energy Levels Asaocialed with Two Electrons in Uulillead Shells
`Rules for Obtaining S, L. and J for L3 Coupling
`Degerieracy and Statistical Weights
`Coupling
`Iaoeleotrouic Scaling
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`E?
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`EEFEIDOCES
`PROBLEMS
`
`-I RADIATNE TRAHSITIJNS AND EIIIIS-SIGN LINEWIDTH
`0'|'E.ll‘I|'IE‘II'
`
`4.1 Decay of F.n:itefl Stalcs
`Rar:|iaIiveDecayofE:rcileriSrateso1'Isol.aieda!Lloms—
`Spontaneous Emission
`Spontaneous Emission Deeay Rate — Rmlistirle Transition
`Probability
`Li:I'e!imo oia Radiating Electron — The Electron as a Classical
`Radiating Hannonic Oscillator
`Nonradiatirre Decay of the Excited States — Collisional Decay
`42 Elnifiion Braadeting and Iinerridfll Due to Radiative Decay
`Classical Emission l..i.nenrid:l1 of a Radiating, Eliecllon
`Namral Emission Linewidllr as Derluceri by Quantum lvIeclran.ir.'s
`[Minimmo Ljrtenririth)
`4.} Additiond Erfnsion-Ilrocadcning Processes
`Broadening Due to hlooratliative (Colfisional) Decay
`Brocarlening Due to Dephasing Collisions
`AItI1rphous Crystal Broadening
`Doppler Broadening i.n Gases
`Voigt Lihape Pmlile
`Broadening in Gases Due to lsolope Shifts.
`Comparison of Various Types ofEm.i$ion Broadening
`-I.-4 Qtlanllli Mechanical D-I!'Sl!I'i|]IilII'I of Ratlirrtirrgfitonrs
`Ejecuic Dipole Ratliation
`Electric Dipole Matrix. Element
`Eloctric Dipole Transition Probability
`Oscillator Suengrh
`Selection. Rules for Electric Dipole Trmsitions lmrolrling Atoms
`wi1lr a Single Electron in an IJnIi.|Ie|:| Subshell
`Seleclion Rules for Rrtlialive Transitions lmrolrling Atoms will:
`More Than One Electron in an Unlillied Subslrell
`
`Parity Sclueclion Rule
`lnefficienr. llariiarive Tr:-msitions — Electric Quadmpole and Other
`Higlrer-Drcler Transitions
`nsncss
`Fnoacssls
`
`5 ENERGY LEVELS AND RAEIATWE PROPERTIES OF MOLECULES.
`LIEIIJIDS. AND SOLIDS
`CWF.ll'a"IElI'
`
`5.1 lblolecular Energy I..e1.rels and Speclrs
`Energy Levels of lvlolerailes
`Classification of Single lhllolsurles
`Rotational Energy Levels oILinear llrlolecoles
`Rotational Energy Levels of fimnietlic-Top Moleorlles
`Selection Rules for Rotational Transitions
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`ED
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`CIIIITEHT5
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`Wlntalzional Eneigy Levnells
`Selection Rule for ‘Vibuational Trmilions
`RotationaI—‘t"ibIational Transitions
`Probabilities ol'Rotati:ona| and Vibrational Transitions
`
`Electronic Eneegy Levels ofMc-laoculiea
`Electronic Transitions and Associated Selection Rules of
`Molecules
`Emission Linewidlh ofMnl'.ecul.ar Transitions
`
`'I11e F|.'anck—Condon Principle
`Exciroer Energy I..E!l|'ElS
`5.] liquid EneI'g3'Le1rekand'l'II:eir]l:|diatinn Properties
`Structure oi Dye Molecules
`Energy Levels offljre Molecules.
`Excitation and Emission of Dye Molecules
`Denimental Triplet Slates. ol'D_',re Molecules
`5.1 Energy I.e1Iels in5oIds— Dielectric Lmer Malerials
`Host Materials
`
`Laser Species — Dopant Iona
`hlarro1.E-I_.ine'widd1 Laser Materials
`Broailnand Tumble Laser Materials
`
`Broadening lI'Iechanistn for Solid—State Lasers
`SA Fatergy Levels in SnIds— Se|IiJeondIueIost' Laser llvlaterials
`Energy Bands in Crystalline Sofids
`Energy Levels in Periodic Stmcltues
`Energy Levels of Coruzluctoua, lruulators. and Sel1ll.(:DI'Id]I.'.tDt'5
`E:cilan'on and Decay ofE:ci|ed Energy Levels — Recombination
`Radiation
`
`Direct and Indirect Eandgap Scmiconductols
`Electron. Elianibution Function and D€II£ll'j' of States in
`Semiconductors
`Intrinsic Semiconductor Materials
`
`Extrinsic Semiconductor Materials —Doping
`p—n .lEI.I1E.'.l2l.DlB — Reootnlsination Radiation Due to Electrical
`Excitation
`
`I'hfEID_f'll_nction ' Mate:1'al!s
`Quantum Wells
`Vaiation of Eandgap Energy md Radiation Wavelength with
`Alloy Composition
`Reeoltlninalion Radiation Transition Probability and Line-width
`IEFEIENCE3
`PIEIIILEE
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`ll
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`II.AD'lATfl3¢N All} THERMAL EQUILIBRIUM — ABSORPTION AND
`5IIfll.iI.A.'I'ED EMISSIJN
`DVEIHEW
`
`6.] Equililn-ital
`Tl'If.l'lTI3l Equilibrium
`Thermal Equilibrium via Contluction and Convection
`Tbetmal Equilibriuro via Radiation
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`I43
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`[SI]
`ESI}
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`ITI}
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`H3
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`OOIIIHITS
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`Ste:l'an—BoItzn1ann Law
`Wierfs Law
`[rradianoe and Radianee
`
`-6.3 Canrity Iladiation
`Counting the Nuloh-er offlavity Modes
`R.a}rIeigh—Jeans Fornmla
`Planck’: Law for Cavity Radiation
`Relationship between Cavity Radiation and Blackbody
`Radiation
`
`Waimlenglh Dependence of Blackborly Emission
`6.4 Ahsorplion and Slimnlakd Emfion
`The Principle oF[IIc1aik:d Balance
`Absorption fllii Stimulated Emission Co-Izfiiaccienls
`IEFEIEECES
`PROBLEMS
`
`SEIHIOH 3. LASER AHPLIFIE
`
`T IEONIII-ITION5 FOR PROEIJEING A LASER — POPULATION
`INVERSIONS. GAIN. AND GAIN SATURHIIOH
`CW'E.R"¢|'IE“'
`
`'.-‘.1 Ahsorplion and Cain
`Absorplion andflain on a Homogenasonsly Broadeneri Radiative
`Transition (Lorentzzian F Distribulion)
`(kin Coefficient and Stilnnlatcri Emission Cross Section for
`
`Hornogmeous Broadening
`Absorplion and Gain on an Inhomogenasous|}r Broadened Radi.aI.i1.Ie
`Transition (Doppler Broadening nrilh a Gaussian Distribution)
`Gain Coeflicient and Stimulated Emission Csom Section for
`
`Doppler Broadening
`Statistical Weigtuts and lie Gain Equation
`Relationship of Gain Coezlficient and S-tilonlaled Emission
`Csoss Section toAb.sorp1ion Coeflieient and Alzisorplion
`Cross Section
`
`1.2 Fopulaiinn Inversion I Nor:-mar} Condition for 3 Lat-r]
`1.3 Salurslioll Intensity {Sufficient Cnnditioll for a Iaser}
`'.-‘.4 Development and Growth of a Laser Beam
`Growth oflileam for a Gain Medium with Homogeneous
`Broadening
`Shape or Geometry ofhmplifiring Medium
`Growlh c-{Beam for Doppler Broadening
`'.-‘.5 Ihpnnential Growl]: Factor {C:l'n]I
`'.-‘.6 "Threshold Ileqilisterlelits for a Laser
`Laser with No Minors
`Laser with One Mirror
`Laser with Two Mirroni
`REFER
`PROBLEMS
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`2!]
`2ir5I
`2E5
`2&6
`2!?
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`CCIITENTS
`
`LASER OSEILLATIOPI ABOVE Tl-IIESHOLD
`lII'|'EI”t']E'W
`8.] Imer Grin Saturation
`
`Rate Equations oftlre Laser levels That lncluiie Stimulated
`Emission
`
`Population Densities ol Upper and Lower Laser levels with
`Beam Present
`
`Slnall-Signal Gain Coefficient
`Sraturatzion ofthe I..aset Gain abo1.neTlIresholri
`
`I12 Ixaer BEIIII Crmrtlr heyuntl the Salnralion Intensity
`(lungs from Experiential Growth to Linear Growth
`Steady-State Laser Intensity
`IL! Oplintimation of laser Outpnl Po-war
`Optimum Output Minor Transmission
`Optimum Laser Output Intensity
`Estimating Optimum l..aserOutput Power
`Er-I Fnergy Exchange between Upper Laser [revel Population and
`Laser‘ Photons
`
`Decay Time ofa Laser Beam within an Optical Cavity
`Basic Laser Cavity Rate Equations
`Steady-State Solutions below Laser Ttner.hoh:l
`S1ea|:ly—State Operation above L:1serT'hI'esho{d
`I15 Lmer Onlpll Flnctuaflions
`Laser Spilting
`Relaxation Oscillations
`
`8.6 I.ase1'.-hnplifiers
`Basic Amplifier Uses
`Pmpagation ofa High-Power, Short-Dusation Optical Pulse through
`an rltrnplzifier
`Sanitation Enesgy Fluenoe
`Amplifying Long Laser Pulses
`Amplifying Short Laser Pulses
`Cornparison c-{Efficient Laser Arnplifiess Based upon Funtl‘.aI:nentaI
`Saturation limits
`
`lu'Iin'or fitrtay ar1d Resonator (Regenerative) Amplifiers
`IEFEIENC
`IIDIILEIE
`
`REQUIREMENTS FDR OBTAINING POPIJLAIIDN INVERSIGHS
`lIl|'EII'a"]E'll'
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`9.] Invasion: and Two-Irevel Systems
`9.2 Relative Decay Ilales — Ibcliati-re versus Collisions]
`9.3 Steady-1-llatelnrersions in Thrce- and Four-I.-evel Systems
`Tluee-Level laser‘ with the Inierrnediale I..etIel as the Uppei Laser
`level
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`Tlnee-l..evel Laser with the Upper Laser Level as the Highest level
`Four—]..evel Laser
`
`El.-II Transient Population lnlrcrions
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`COHTHITS
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`9.5 Pmeease-5 Thal lrlliliit orI}estro_gr 1I]'l-'E'fS10I15
`Radiationfiapping in Atortm and loos
`Elocsron Colliaionai The::matiza.tion of the Laser Levels in Atoms
`and lons
`
`Comparison oi Radiation Trapping and Election. Collisional Mixing
`in a Gas Laser
`
`Absorption within the Gain Medium
`|1EI'EE'DH]?.5
`PREIIIIIIIS
`
`1|} LASER Pl.l|'||I3IflG REQUIREMENTS AND TECHNIQUES
`l.'WE.I‘.'|'lE“"
`
`10.1 F.xeitalion or PiIlpiIgTlireaIioId Ilequirements
`10.2 Ptmtping Palln-rays
`Excitation by Direct Pumping
`Excitation by lodirect Pumping (Pump and Trmsfafl
`Specific Pump-arI.d—TransIer Processes
`10.3 Specific Excitaliim Parameters Assn-|:iale~d with
`Optical Ptltnping
`Pumping Coolzneirica
`Pumping Roqoiremcms
`A Simplified Optical Pumping Approximation
`Transverse Pumping
`End Pumping
`Diode. Pumping of Soiid—SIalo Lmors
`Characterization ofa Laaerflain Medium with Optical Pumping
`{Slope Efficiencjri
`10.4 Speeifie 1-Ixeitalion Parameters Asaoeialed with
`Particle Plumping
`Elocstmn Collisional Pumping
`Hcavjr Pmficlc Pumping
`A Morefitocurate DescIipI.ic~n ofElectmn Excitation Rate to a
`Specific Enczgy Lave! in a Gas Discharge
`Elemrical Pumping offlemiconduclors
`|1EI'EE@I]?.5
`PRIJILEHIS
`
`SECTION I. LASER RESONATORS
`
`11 LASER CAHITY MODES
`D'-VEI‘.'l"IEW'
`11.1 [ntroduetinn
`
`11.1 Loogiudirnl Laser Cavigr Modes
`Fal:rr)r—Picrol Resonator
`Fahr}r—Perot Cavity Modes
`Lon.gitud;inal. Laser Cavity Modes
`Longiordinai lIn'It'.|d:E'. Number
`Requirements for die. Developincm oi L.ong;iIndinal
`Laser Mode:
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`31]
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`3l5
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`322
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`32?
`330
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`351'.
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`355
`359
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`359
`36]
`363
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`3'31
`3'39
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`330
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`CCIHTEHTS
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`I 1.3 THIISI-‘I!l'9I? Laser Cari} Modes
`FIesrueI—KirohhofI Difliaolion Integral Formula
`Development ofTranswrse Modes in. aCa.1I.Iity widi. Plane—F‘.ua.llel
`Mirrors
`
`Transverse Modes Usingflurirod Mirrors
`Transverse Mode Spatial [.‘risI:ilJm‘.ions
`Transverse Mode Frequencies
`Gaussian—S|1ap-e¢!T|:ansvezse Modes wifliin and beyond Ihe
`laser Cavity
`I 1.4 Properlies of laser Modes
`Mock-. fim
`Effiectoflvlodeson die Gain Medium Profile
`REFERENCES
`PIOIIIHS
`
`12 STABLE LASER RESDHATDRS AND GAUSSIAN BEAMS
`OVERVIEW
`Ill Slable Cu11'HI Mirror Cavities
`Cunrexi Minor Cavities
`ABCD Matrices
`
`Cavity Stability C:iIe:ia
`I12 Properlies of Calmian Beams
`Propagation of aflaussian Beam
`Ihilssian Beam Plopmties oI'Turo-Minor 1.aserCavities
`Properties ofspeoifle Two-Minor Laser Cavities
`Mode Volume of:-1 I-lero1i1e—Ga.ussian Mode
`
`of Real Laser Beats
`IL!
`ILI Prnpuagafion offlalmiai Ilieanui lJsing.4IH’CI.'l Matrices-
`Complex Ilean Paramcll.-r
`Complex Beam Pararouserfisppliud to aTuro-Minor 1.aserCavity
`IEFEIENC
`PIOIIIHS
`
`13 SPECIAL LASER CAHITIES AND CA'U'lT‘I' EFECTS
`OVERVIEW
`I3.I Ullflable Resonafiors
`
`I32 Q-Suiltliing
`General Descriplion
`Theory
`Methuzls o-fProd.IJc:ing Q—Swi§el:|ing wil['rin a Lases Cavity
`ILL! Ca'n-Switching
`I3.-I Mode-I..oclLiog
`
`Theory
`Techniques for Producing MI:I:le—Looking
`I35 1'-'l:he5I1orleningTedII'ques
`Self-Phase Moclulalion
`
`Pulse Shortening or laengdiening Using Group Velocity Dispersion
`Pulse Coropressiorn [filaaorteningl with Gratings or Prison
`[]'lt:ashon—PuIse Iaserand Aloplifer System
`
`All
`
`-125
`418
`432
`-$32
`
`(cid:3)
`
`(cid:3)
`
`10
`
`(cid:3)
`
`10
`
`

`
`ODIIIHITS
`
`1.1.15 Ring Imers
`Monolithic UnidiI13:cI.ion:aI Single.-Mode hld:YA.{] Ring Laszr
`Two-Minor Fling Laser
`1.1.7 Complex Beam Pamneter Analysis Applied to I't-Itlti-Mirror
`Lmtr Cavities
`
`Tltrcc-Mirror Ring Laser Cavity
`Thrcc- or Four—Min'or Focused Cavity
`13.8 Cavities for Producing Spectral Plarrouing of
`laser flutpul
`Cavity with Additional Fahry—PEsotE1;aIon for hla:Tow—]-irocpency
`Selection
`
`Tunable Cavity
`Bmadlxand. Tun-able cw Ring Lasers
`Tunable Cavity for Ultlanazrour-Frequency Output
`Distributed Fcodback {DFB} lasers
`Distributed Bragg Roflcction Lmcrs
`1.1.9 LHI.-r Cavilic-s floqoiriug Sliall-Diauwter Gin Regions —
`Asliglatically Compensated Carilir-s
`1.3.10 Waveguide Caxilies for Ca: Iran:
`REFERENCES
`FRDILEM5
`
`SECTION 5. SPECIFIC LASER S"I"':TI'EHS
`
`14 LASER SYSTEMS IN"|I"DL"o"IHG LOW-DEHSFFY GAIN IIIEDIA
`DVEIIIIEW
`14.1 Atomic Cat: 12921:
`introduction
`I-1elilI—Ncon l..a-scr
`
`Genara] Descfiption
`Laser Stluolnm
`Excitation Mcchanism
`
`Applications
`Argon [on Laser
`Gencral Destxipti-on
`laser Stluoturc
`Excitation Mechanism
`
`Krypton [on Laser
`Applications
`I-1elilI—Cadmiuu1Las=er
`
`General Description
`Laser Stnnzturc
`Excitation Mcchanism
`
`Applications
`Copper Vapor Lmer
`General [Description
`laser Suuolurc
`Excitation Mechanism
`
`Applications
`
`4'I'{I
`
`4'i|'l]
`4'i'{I
`4'13
`
`4'13
`
`4'I'E
`4'I'E
`4&0
`4ErI]
`4B|
`
`455
`456
`433
`
`49 I
`49 I
`49 I
`49I
`492
`
`493
`494
`49?
`49?
`49?
`493
`
`§§§§§§§§§§§§§
`
`(cid:3)
`
`(cid:3)
`
`11
`
`(cid:3)
`
`11
`
`

`
`CCIITEHTS
`
`I42 Molecularflas Lasers
`Introduction
`Carlmn Dioxide Laser
`
`General Elescriplioo
`lanes‘ Slrucnlre
`Excitation Mechanism
`
`Applicalions
`Exciner Lasers
`
`General Descriplion
`laser Smicture
`Excitation Mechanism
`
`Applicalions
`Nitrogen laser
`General Elescriplioo
`laser Slnicsmre and Ezccilalion Mechanism
`
`Applicalions.
`Far-Infrared Gas Lasers
`
`General Desncriplion
`Laser Strucmre
`Exci:a1ioo. Mechanism
`
`Applicalions
`Cliunical Lasers
`
`General Elescriplioo
`Laset Slrucmre
`Excitmion Mechanism
`
`Applicalions
`I4.3 I-Ray Plasma I...a9ers
`Inlroduulion
`
`Pornping Energy Requiremems
`Exciimion. Mechanism
`
`Dplical Cavities
`)(—Ray Laser Transitions
`Applicalions
`I444 Flee-Electron Lasers
`Intmdoczion
`Laser Slroeture
`
`Applicalions
`Iisslznsucss
`
`15 LASER SYSTEMS HIUOLVING HIGH-DENSl'|:"I" GMII MEDIA
`ovmvmw
`
`lS.l Organic Dye Lasers
`Io1n:x|‘.necion
`]..asea' Slnicsmre
`Elciiation Mechanism
`
`ilipplicalions.
`lS.2 Solid-State Lasers
`Innuduution
`
`51D
`5llJ
`5] I
`
`5] I
`5] I
`515
`
`515
`516
`
`516
`5]?
`518
`
`521]
`52]]
`521]
`52I
`
`522
`522
`
`522
`523
`523
`
`524
`514
`
`524
`524
`524
`
`525
`525
`525
`
`525
`523
`
`532
`532
`532
`535
`535
`536
`
`53?
`531'
`
`539
`539
`
`539
`539
`54!]
`543
`
`544
`545
`545
`
`(cid:3)
`
`(cid:3)
`
`12
`
`(cid:3)
`
`12
`
`

`
`55 I
`553'-
`554
`555
`555
`556
`556
`55?
`55?
`55?
`557
`553
`553
`55'}
`55'}
`
`CCIITEITS
`
`Ruby Laser
`Genetal [k.'s£:ripliI:|n
`Laser 5II1.II:!.l.Il'E:
`Excitalion lluloolianism
`
`Applications
`N-fillynium ‘YAC and ‘C123 Iaslers
`Genera! Deacriplioui
`laser S1md.u:e
`Excilaiion Mechanism
`
`Applications
`NeoII}'nI'nm:YI..F Lasers
`General Elasorip-I.ion
`Laser Sllumue
`Emitajion lklocllanism
`
`Applications
`NeoIl].'nI'um:‘t'll.rim1 Iianadate { N|i:YVO4]I Lasers
`Geneta! Eleacriplion
`Laser Slnlctuse
`Excitalion hloollanism
`
`Applications
`'t'llcrbiml:‘I'AC Lasers
`
`Genetal [k.'s£:ripliI:|n
`Laser 5II1.II:!.l.Il'E:
`Escilalion Inloollanjsm
`
`Applications
`Alunndrile Lmer
`
`Genera! Deacriplioui
`laser S1md.u:e
`Excitafion Mocllanism
`
`Applications
`Tl.IiI'lIl.IIII'I Sapphire I...a.ser
`General Ellosoriplion
`Laser Slmfiure
`Excilalion lIn'IE:cl1.an.iso1
`
`Applications
`Chroulili l..iSAF and l.iCAF lasers
`
`Geneta! Eleacriplion
`Laser Slnlctuse
`Excitalion lklodlanism
`
`Applications
`Fiber Lasers
`
`Genetal [k.'s£:ripliI:|n
`Laser 5II1.II:!.l.Il'E:
`Escilalion Inloollanjsm
`
`Applications
`Color C-eI|tfi'I.uE1's
`
`Genera! Deacriplioui
`laser S1n|d.u:e
`
`(cid:3)
`
`(cid:3)
`
`13
`
`(cid:3)
`
`13
`
`

`
`CCIITEHTS
`
`Excitation Mechanism
`
`Applications
`I53 Semiconductor Diode Lifll.‘l‘S
`[Introduction
`
`Four Buio Types of Laser Materials
`l..a5e:' Str1Je:1It'e
`
`Frequency Control of l..aser Output
`Quantum Cascade Lasers
`p-Doped Gennaniulzn Lasers
`Exeitation 1't{ec|1an.isIn
`
`Applicaljotts
`IILEFEIENCES
`
`SECTIIEII 6. FRECILIJIEHCY HULTIPLIEATIDH OF LASER BEAMS
`16 FREQUENCY MULTIPLHIATIDH OF LASERS AND OTHER
`HCIILINEAR OPTICAL EFFECTS
`fll'IIll'u"]I7'tI'
`
`lIS.l Wave Propagation in an Anieolropric Crystal
`I62 Polarization Response offirlalerials to Light
`I63 Second-Order NnId'near flplieal Pmoc-mes
`Seoond Harrnonic Generation
`
`Sum and Differenoe Ft'equenc:y Generation
`Dpljoai Parametric Deecillaiien
`IISJI Third-Order Nonlinear Dptical Procvmc-5
`Thin! Harmonie Generation
`
`i1IlEllEil'_'||'—DEpEI'IdI:‘.llI Refraetive Index — Seif-Focusing
`IE5 Nonlinear flptical Materials
`I615 Pllme Matching
`Description offltase Matelting
`Achieving Phase Matching
`Types of Phase Matching
`Il5.T Sattlrable Absorption
`I63 Tl'l'l'.|~PIHlII0lII Absorption
`ll5.'.I Slimldatcd Raman Scattering
`lIS.lIl]' llanionic Generation in Cases
`REFERENCES
`
`Appendix
`Index
`
`574
`5715
`576
`576
`5T9
`SEI
`59I
`5%
`594
`594
`596
`5'3’?
`
`61 I
`62.5
`
`(cid:3)
`
`(cid:3)
`
`14
`
`(cid:3)
`
`14
`
`

`
`1 I
`
`ntroduction
`
`-DUEEUIEW A l;ase:r is a device lint amplifies light
`and produces a highly directional. high-imemiry
`bealnlhatmofioftenliasavelypure frequencyor
` . ll comesinsiees ranging lrom approx-
`inistelyolietenlhlhediamelerofalmlisanhairlso
`Ihesii:eofavetyla.lgebnildi.ng.inpnwersrangir|g
`from I04‘ to I03" ‘W, and in wavelengths ranging
`fI'omEJ1emicro'wavetolhesoft—X-rayspectraliegimls
`with ooiresponding freqmncies from EU" to H1" H1.
`Lmershavepu|seene:giessshigl1.ss ll]‘Jmd pulse
`dnral.ionss.ss]IoIt:ai5 3-: I-l]"5 s. Theyesnly
`mill hnlesin Ihe mosldurshle ofmslerislsand-can
`
`of I.'.'li.flEI1I:e!
`
`welddelsachedretiriaswilhinllselmmaneye. They :-ne
`alcey component ocfsmneofourmost modem com-
`ltmniczlliort systemssnd a1elhe'"phonograph nee::lle"'
`clourcompactilisc players. They perform lIesttIeat-
`meniofhigh-strenglh matelials. aloha die pistons of
`ourantsomobile engines. and provide a. special surgi-
`csllznife for many types olfmedicsl p|tI::e¢k1res_"[hey
`aclaslsrgeldesigmltors for mililasy weapons andpro-
`vide for Iiverapidcheck-out we ltaveeornetoexpect
`at l.l'IE sup-enI1srket.'WlIaI a remarEableIangeol'chaI-
`aelseristics fnradeviee Ihslis in only its liflil decade
`
`INTRDDIJCTIJN
`
`There is nothing magical about a laser. It can be thought ofasjust another type
`of light source. Itcertainly has many unique properli that make it a special light
`source. but these propeniesean be understood without tnowledgeof sophisticated
`matlIemal.ica.I techniques oreomplea ideas. It istlle objective oflhis text loexplain
`the operation oflhelaserina simple, logical approach l'l1a1bui|dsfromou1eooI1—
`eeptluotheneatasilzlecliaptersevo-Ive. Tl1eooIIcepts,mll:|eyarel:lev1eioped, will
`he applied to all classes of laser malerials, so that tlve reader will develop a serme
`oi the broad field oi lasers while still aequiringtlie capability lostudy, design, or
`simply understand a specific type of laser system in deiai:L
`
`DEFINITIOIII OF THE LASER
`
`The 1v-oltl laser is an acmnym for Light Aniplificflion by Stimulated Emission of
`R.adi:H.iorL The laser makes use of prooesses that increase or amplify light signals
`aflerthose signals have been genelated by other means. These pm-(T include
`(I) stimulated emission, a oatunfl effect that was deduced by eonsideratinns re-
`lating lo tllemlodynamie equilibrium, and {2} optical feedback {present in most
`
`(cid:3)
`
`(cid:3)
`
`15
`
`(cid:3)
`
`15
`
`

`
`INTRODUCTION
`
`Clplieal resonator or eauity
`r'
`Amplllyiig rnedlum
`
`
`
`Partlall-.-1-ansm-1ting
`niror
`
`in-‘l-I Fnipilieel
`sdleindicoltgrpicalhsar
`
`Fully rmlecting
`rriror
`
`luets) that is usually provided by ntinols. Thus, in its simplest foernt, a l:uer4:o11-
`sists of a gain or alnplifying Inediuui Iwlleie Sl.lJ'I2IIl.lI1l:E£l emimion oeeurs',l, and a
`setofmirrors to feed the Iighthaek intolhe alnplitierforeontinued grnwlhofthe
`developing heam, as seen in figtle I-l.
`
`5IPfl5'I.lCI'I'Y OF A LASER
`
`Tlaesiunplieityofalasereiai heunderstoodhy eonsideting the light from acanclle.
`Nonnally, a hunting candle nadiales light in all directions, flld thelefore illumi-
`nates various ohjeets equally if thejr are equidistmt floin the eaidle. A lasertales
`light tllat would normally be emitted in all direetiolis, such as from a candle, and
`eoncerilnles that light into a single direction. Thus, iflhe light naclifling in all di-
`reofiocsfiomaearallewerehatedinmasinglehealnoffllediuneterofflie
`pupil ofyottreye fappmxinlalely 3 nun], and ifyml were standing adistanee of
`lmfrom lheeandle, Ihen thelight interuity wouldhe |,l.'I]l.tIIl times H hrightas
`the light that you normally see radiating from the ttmdlel That is essentialljr the
`urideflyingoomxptoftheoperali.-out ofalaser. However, acandle isnot the kind of
`medium tlnl prnduees amplification, and thus there are no cantle lmers. It ties
`relatively special conditions within the Imer meaditun for amplification to oeeur,
`but it istilat cqiahilityoflaking light that would normally Iadisle from asoume in
`all diieelioru — and eolieerimling that light into ahean uaveling in a single dltE!.':-
`1ion—Ihu is involved in Initingalaser. These special conditions, and the media
`within which they are produced, will hedeserihecl in soinedetail in this hook.
`
`UNICILE FIIOFERTES CI: ALASEII
`
`Theheainofliglitgelleruedhgratgrpical lnsei'eaI1havrernan'_I,rpln|:IerIies1I1atu'e
`unique. when oompa1inglaaerprnpertiestothoaeofotherliglbtsnuroes,ite:Ii
`l:e Iea1:lil}r reuigllizned that the values of various paameters for laser ligll lher
`gleailyexoeedoraremuehnmrerestdefivelhanflievaluesfinnintyoomnuin
`Iiglllsouloes. We never use lasers Eorstreet illumination. orforillumination within
`our llotaes.
`‘We don't use them for seanehlights or flashlights or as headlights in
`
`(cid:3)
`
`(cid:3)
`
`16
`
`(cid:3)
`
`16
`
`

`
`IH1'EDl.ICT|DH
`
`our ears. Lasers generally have :1 narrower flequeuey distsibuticnn, or much. lliglter
`intensity. or I1 rnueh greaterdegree Dl£.13ll.irlIfll'.i[II, or much shorter pulse dursl.i.=un,
`Ihsnlhsr evailflsle [mm more common lypesnfliglir sources. Theiefure, we flu use
`drern in. eulrnpect disc players, in supermsrtcet cheek-oul sesnnels, in surveying in-
`slnlsnems, and in medical appliesliarls as :1 surgical knife or for welding cletsellert
`retinas. We also use them in eomnvunieatiulzis systems and in mint and militssy
`targeting applicafinrrs, as well as many other mean. A laser is is specialized light
`source that skould be used cu-r.I!'y when its unique properties are required.
`
`THE LASER SPECTRUM All} WAVELENGTPES
`
`A pcu1.i.un nfdrne eleaelzlnnlsgnetiar: radiation qsectrum is drawn in Figure I-2 fur the
`regiIJnomreru:l by cunenfly existing lasers. Snell lasers spam the wavekrnglli range
`from the fsrilnfrsrerl pert ufdzle spectrum {IL = IJIKI um} In the snfl—X—rey region
`UL = 3 nm),the:ehyooIerh1garang1enfwn1eleIigtl:sofahnr:n1six(mleIs IJfn1ag-
`nitude. There are several types of units that sue used to define laser wavelengI.IIs.
`These range from Inic:rolI|eterscJrn1ieruIrs[;.rIn}intI|eint'mI1:d to nanlnrlletersfnrll)
`and angstroms {All} in the visible, u]t.n1v'iulet[UV), vacuum ultraviolet {VUV ], ex-
`treme ultrsrviolet {EUV or}CUV], and sufl—X-my [SXR] spectral regions.
`
`'|'£I'N'ELEl|IG"I'H I.|llI'l"S
`
`l_u.rn = lll_Ell1:
`H.210-“m;
`lnm= [D4 In.
`
`Consequently, I niieran {urn} : I{},|IIIlangst.run|s {ill} : lifllnannmeless {um}.
`Furexslrlple. green Iiglstbas Inveirelenglh-rJf5 3-: H14 m =l}.5 use = 5,[II|A =
`SCI) run.
`
`_-___
`
`..
`
`.
`HF
`
`I
`_.___
`
`D''‘“’°
`19 '3"
`Ar
`..
`..
`
`.,.
`
`CG
`
`_
`
`____
`
`..
`
`l
`I
`1-21"
`H
`(Huge uf1'iI'in-L|5 lasers
`
`.
`i
`
`FIR Lasers.
`..
`..
`
`"2
`Hub?
`KrF
`H9-Ne
`Nd:‘|'.M3
`HR l.'..‘.|I
`
`San-I-Hay
`Lasers,
`..
`..
`.
`-
`
`CC}?
`
`He He
`
`Ffll Infrared
`
`Ifilrured
`
`Eugenie Dpe_
`Tl.n3.|2C|3
`".I'iu|:I|rI
`
`.I1rF
`Uhlervulel
`
`Sta‘! Ill-Ray:
`
`supm 1u»pm
`
`1pm-3I:H:Inm1I:HJnm 3-Clnm
`apm
`.. is
`he‘
`-——--ENEst:a*r{T;
`
`-.
`
`Hnnm
`
`(cid:3)
`
`(cid:3)
`
`17
`
`(cid:3)
`
`17
`
`

`
`IHTIIODUCTIDH
`
`IIEHIELEIIGTH IIEGIDHS
`
`Far infrared: II] to I,[l]1 um;
`middk: infrared: I to 10 _u:m;
`nearinI'rared: 0.? to lj.'.[.lI1;
`visible: 0.4- to l].'i" run. or 4I'.I}to ill) mo:
`ultraviolet: I12rol}.4 pl.ll'l, or2lIIto-ill) mo‘.
`vacuum ultraviolet: 9.] to 9.2 um, or Ill] to Ellhtm;
`extreme ultraviolet: 10 to It'll] nm;
`soft X-rays1 ] nm to approximately 211-30 nm {some overlap with EUV].
`
`A BEEF HISTORY OF THE LASER
`
`Cha:rlesTtmrnes took advantage ofdae stimulated emission process toconstruct a
`microwave amplifier, referredtouamaser. This device jzirnducedacoherent beam
`of microwaves to be used for corrtmunicaiions. The lirst maser was produced in
`ammonia vapor with the inversion between two energy levels that produced gain at
`awavelenglh oi L25 cm. The wavelengths produced in the ntaserwere compara-
`ble to the dimensions of the device, so eimapn-laiion to the optical regirne — where
`wavelengths were live orders ofrnagnittlcie srnaller— was not an obvious extension
`of that work.
`
`In 1953, Townes and Schawlow publisher! a paperconcerning Iheiridem about
`extending the maser concept to optical frequencies. They developed the concept
`-nfan optical amplifier surrounded by an optical l'l2Ill'I1J]' resonant cavity to allow for
`growth olthe bea.rn. Townes andS-chawloweaeh rcceivedablohel Price forhis
`worlz in this field.
`
`In 1960, Theodore Maiman of Hughes Research laboratories produced the
`first laser using aruby crystal 3 the amplifierandallashlanipm the energy source.
`The helical flashlamp sunoundetl a rod-shaped ruby crystal, and the optical cavity
`was lormed by coating the flattened ends oflhe ruby rod with a highly reilecting
`material. Anintenseredbeamwas-observedtnernergefrnmtheerid oflherod
`when the flashlamp was Iiredl
`The tilstgaslaserwmdevelopedin l'9I5| byAJavai1.,"W. Bennett. and D. Han"-
`Iiott oi Bell Laboratories, using a mixture of helium and neon gases. At 1he same
`laboratories, L. F. Johnson and K. Nassau demonstrated the first nectlymium laser,
`wltichhassiricebecomeonenftltemnstreliahle lasers available. Thiswas followed
`
`in I962 by the first semiconductor laser, dernonshated by R. Hal] at the General
`Electric Research Laboratories. In 1963, C. K. N. Patel of Bell laboralories dis-
`covered the infrared carbon dioxide laser, which is one of use most efliacient md
`jzllwerfill lasers available
`Liter that same year, E. Bell -of Sjrxxra Physics
`discovered the lirst ion laser, in me:rctu'y vapor. In 1964 W. Bridges of Hughes Re-
`search LaI:I:raIori discovered the arg-ctli ion laser, and in |9€l‘.'I
`‘W. Silfvafl, G. R.
`Forwles, and B. D. Hopkins produced the lirst blue heliuIn—cadm.itIm metal vapor
`
`(cid:3)
`
`(cid:3)
`
`18
`
`(cid:3)
`
`18
`
`

`
`IHTIIDIIJCTIDH
`
`laser. During Ihatsarne year, P. P. S-orolzinand J. R.Lrl1kard of1heIEM Research
`Lxborai developerllhe lira liquid laser using annlgarriacdyerfissrnlvul in asoI-
`vent, thereby leading to the category of broadly tunable lasers. Also at that time,
`\If.‘Wallerandco-worlaers atTRGrcpor1ed the lirsteoppervaporlaser.
`The first vacuum ultraviolet laser" was reported to occur in molecular hydro-
`genb-}rR.HodgsonofIBMandindeper1dernlyh3rlLWa3na11te1al.oflheNaval
`Research I_.abora:nri.es in I970. The hr: of lbe well-lzncrwn
`ex-
`ctimer lasers was observed insenonfluoridebyl. J. Ewingandfl. Brauofthe
`.Purco—Everel1 Reseaavch l_aboraIor_-,' in I975. In that same year, the first quantum-
`well laser was marfie in a gallium arsenide serniconduclor by I. van der Ziel and
`co-workers at Bel] I_a.borator'ies. In I976, I. M. J. Macley and co-workers 51 Stan-
`ford University tlaernorlsnated the lirst free—electron laseramplifleroperaling in the
`infrared at the C0; laser wavelenglh. In l9T9, ‘Walling and co-worlrers 3 Allierl
`Ch-ernicaICorporati.on obtained broadly tunable Iaseroulputfrornasolid-stalelaser
`material called alesanrbite, and in I935 the first sofl—X—ra3r laser was successfully
`derraJnsl.rate::linabigbl_',rior1izerlseIunI
`D. hIla11hewsa.ndalslgenum-
`ber of co—workers at the Lawrence Livermore Laboratories. In IQEIS, P. Iuloulton
`discovered the Iitalirnn sapphire laser. In ]'99I, M. Hasse and co-workers devel-
`oped the lirst hlne—green diode Iaserin fZr1Se. In 1994, F. Capasso and co-worlters
`developed the quantum cascade laser. In I996, S. Nakamluadevelopai the first
`blue diorle laser in GaN—haserl materials.
`In ]'96l. Fox andI..i describerlthe esistenceofresorrantuansverse modes in
`
`a laser cavity. That same yea", Boyd and (hrrlon obtained solutions of the wave
`equaiion for confocal resonator modes. Unstable resonators were demonstrated
`in I969 by Krupke and Sony and were rlescribed theoreiicallgr by Siegman. Q-
`switching was fizlst obtained by h'Ic.C'|ung and I-Iellwarth in 1962 ar1d described
`later by Wagrrer and
`The first mode-locking was obtained by l'IaIgrD‘\-'8,
`Fork, and Pollack in I964. Since then, many special cavity anangemenis, feetflrack
`scllernes. and otberdevices have heer1 developed to improve thecontrol. operflion.
`and reliability of lasers.
`
`OVERVIEW OF '|1'lE BOOK
`
`Isaac Newlnn l2ll.'.SI:l'IlJB£l light as small lJlIIll'.B.5 emilled frorn fltining substalces.
`This view was no doubt influenced by the fact that light appears to propagale in a
`line. Chriaian Huygens. on the other hard. dmcrilzred light as a wave n1.o-
`tion in which a small source sprearbi out in all directions; most observed effects —
`including diffrE:IiorI.. reflection, and rel'racI.irrn —ca1 be attributedtoihe expansion
`ofprima'}r wa