ElectromagneticPropagationinMulti-ModeRandomMedia.HarrisonE.Rowe Copyright©1999JohnWiley&Sons,Inc. PrintISBN0-471-11003-5;ElectronicISBN0-471-20070-0 Electromagnetic Propagation in Multi-Mode Random Media Electromagnetic Propagation in Multi-Mode Random Media HARRISON E. ROWE AWILEY-INTERSCIENCE PUBLICATION JOHNWILEY & SONS, INC. NEWYORK/CHICHESTER/WEINHEIM/BRISBANE/SINGAPORE/TORONTO Designationsusedbycompaniestodistinguishtheirproductsareoftenclaimedastrademarks.Inall instanceswhereJohnWiley&Sons,Inc.,isawareofaclaim,theproductnamesappearininitial capitalorALLCAPITALLETTERS.Readers,however,shouldcontacttheappropriatecompaniesfor morecompleteinformationregardingtrademarksandregistration. Copyright©1999byJohnWiley&Sons,Inc.Allrightsreserved. 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To Alicia, Amy, Elizabeth, Edward, and Alison, and to the memory of Stephen O. Rice Contents 1 Introduction 1 References 3 2 Coupled Line Equations 5 2.1 Introduction 5 2.2 Two-Mode Coupled Line Equations 6 2.3 Exact Solutions 8 2.4 Discrete Approximation 11 2.5 Perturbation Theory 13 2.6 Multi-Mode Coupled Line Equations 15 References 19 3 Guides with White Random Coupling 21 3.1 Introduction 21 3.2 Notation—Two-Mode Case 23 3.3 Average Transfer Functions 25 3.4 Coupled Power Equations 30 3.5 Power Fluctuations 35 3.6 Transfer Function Statistics 39 3.7 Impulse Response Statistics 43 3.8 Discussion 46 References 47 4 Examples—White Coupling 49 4.1 Introduction 49 vii viii CONTENTS 4.1.1 Single-Mode Input 50 4.1.2 Multi-Mode Coherent Input 51 4.1.3 Multi-Mode Incoherent Input 51 4.2 Coupled Power Equations—Two-Mode Case 52 4.2.1 Single-Mode Input 52 4.2.2 Two-Mode Coherent Input 55 4.2.3 Two-Mode Incoherent Input 58 4.3 Power Fluctuations—Two-Mode Guide 58 4.3.1 Single-Mode Input 60 4.3.2 Two-Mode Coherent Input 60 4.3.3 Two-Mode Incoherent Input 61 4.3.4 Discussion 62 4.4 Impulse Response—Two-Mode Case 64 4.5 Coupled Power Equations—Four-Mode Case 67 4.5.1 Single-Mode Input 69 4.5.2 Multi-Mode Coherent Input 72 4.5.3 Multi-Mode Incoherent Input 72 4.6 Nondegenerate Case—Approximate Results 74 4.6.1 Average Transfer Functions 75 4.6.2 Coupled Power Equations 77 4.6.3 Power Fluctuations 81 4.6.4 Discussion 84 4.7 Discussion 84 References 85 5 Directional Coupler with White Propagation Parameters 87 5.1 Introduction 87 5.2 Statistical Model 88 5.3 Average Transfer Functions 91 5.4 Coupled Power Equations 93 5.5 Discussion 95 References 97 6 Guides with General Coupling Spectra 99 6.1 Introduction 99 6.2 Almost-White Coupling Spectra 100 6.2.1 Two Modes 101 CONTENTS ix 6.2.2 N Modes 104 6.3 General Coupling Spectra—Lossless Case 106 6.3.1 Two Modes 109 6.3.2 N Modes 110 6.4 General Coupling Spectra—Lossy Case 115 6.4.1 Two Modes 116 6.4.2 N Modes 118 6.5 Discussion 121 References 122 7 Four-Mode Guide with Exponential Coupling Covariance 123 7.1 Introduction 123 7.2 Average Transfer Functions 126 7.3 Coupled Power Equations 127 7.4 Discussion 127 8 Random Square-Wave Coupling 129 8.1 Introduction 129 8.2 Two Modes—Binary Independent Sections 132 8.3 Two Modes—Binary Markov Sections 135 8.4 Four Modes—Multi-Level Markov Sections 138 8.5 Discussion 143 9 Multi-Layer Coatings with Random OpticalThickness 145 9.1 Introduction 145 9.2 Matrix Analysis 147 9.3 Kronecker Products 150 9.4 Example: 13-Layer Filter 152 9.4.1 Statistical Model 153 9.4.2 Transmittance 155 9.4.3 Two-Frequency Transmission Statistics 155 9.5 Discussion 158 References 159 10 Conclusion 161 References 162 x CONTENTS AppendixA Series Solution for the Coupled Line Equations 163 References 168 AppendixB General Transmission Properties of Two-Mode Guide 169 References 173 AppendixC Kronecker Products 175 References 177 AppendixD ExpectedValues of Matrix Products 179 D.1 Independent Matrices 179 D.2 Markov Matrices 183 D.2.1 Markov Chains 183 D.2.2 Scalar Variables 184 D.2.3 Markov Matrix Products 186 References 190 AppendixE Time- and Frequency-Domain Statistics 191 E.1 Second-Order Impulse Response Statistics 191 E.2 Time-Domain Analysis 195 References 196 AppendixF Symmetric Slab Waveguide—LosslessTE Modes 197 F.1 General Results 197 F.2 Example 200 References 202 AppendixG Equal Propagation Constants 203 AppendixH Asymptotic Form of Coupled Power Equations 209 AppendixI Differential Equations Corresponding to Matrix Equations 211 I.1 Scalar Case 211 I.2 Matrix Case 212 CONTENTS xi References 214 AppendixJ Random Square-Wave Coupling Statistics 215 J.1 Introduction 215 J.2 Binary Sections 217 J.2.1 Independent 218 J.2.2 Markov 218 J.3 Multi-Level Markov Sections 219 J.3.1 Low-Pass—Six Levels 219 J.3.2 Band-Pass—Five Levels 224 References 226 AppendixK Matrix for a Multi-Layer Structure 227 Index 231 Electromagnetic Propagation in Multi-Mode Random Media