Table Of Content

Introduction to Information Optics This page intentionally left blank Introduction to Information Optics Edited by FRANCIS T. S. YU The Pennsylvania State University SUGANDA JUTAMULIA Blue Sky Research SHIZHUO YIN The Pennsylvania State University ® ACADEMIC PRESS A Horcourt Science and Technology Company San Diego San Francisco New York Boston London Sydney Tokyo This book is printed on acid-free paper. (S) Copyright © 2001 by Academic Press All rights reserved No part of this publication maybe reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or stored in any information storage and retrieval system without permission in writing from the publisher. Requests for permission to make copies of any part of the work should be mailed to: Permissions Department, Harcourt Brace & Company, 6277 Sea Harbor Drive, Orlando, Florida, 32887-6777. ACADEMIC PRESS A Harcourt Science and Technology Company 525 B Street Suite 1900, San Diego, California 92101-4495, USA http://www.academicpress.com ACADEMIC PRESS 24-28 Oval Road, London NW1 7DX, UK Library of Congress Cataloging Number: 2001089409 ISBN: 0-12-774811-3 PRINTED IN THE UNITED STATES OF AMERICA 01 02 03 04 05 SB 9 8 7 6 5 4 3 21 Contents Preface Chapter 1 Entropy Information and Optics I 1.1. Information Transmission 2 1.2. Entropy Information 4 1.3.. Communication Channel 9 1.3.1. Memoryless Discrete Channel 10 1.3.2. Continuous Channel 11 1.4. Band-limited Analysis 19 1.4.1. Degrees of Freedom 23 1.4.2. Gabor's Information Cell 25 1.5. Signal Analysis 26 1.5.1. Signal Detection 28 1.5.2. Statistical Signal Detection 29 1.5.3. Signal Recovering 32 1.5.4. Signal Ambiguity 34 1.5.5. Wigner Distribution 39 1.6. Trading Information with Entropy 41 1.6.1. Demon Exorcist 42 1.6.2. Minimum Cost of Entropy 45 1.7. Accuracy and Reliability Observation 47 1.7.1. Uncertainty Observation 51 1.8. Quantum Mechanical Channel 54 1.8.1. Capacity of a Photon Channel 56 References 60 Exercises 60 vi Contents Chapter 2. Signal Processing with Optics 67 2.1. Coherence Theory of Light 67 2.2. Processing under Coherent and Incoherent Illumination 72 2.3. Fresnel-Kirchhoff and Fourier Transformation 76 2.3.1. Free Space Impulse Response 76 2.3.2. Fourier Transformation by Lenses 77 2.4. Fourier Transform Processing 79 2.4.1. Fourier Domain Filter 79 2.4.2. Spatial Domain Filter 82 2.4.3. Processing with Fourier Domain Filters 83 2.4.4. Processing with Joint Transformation 85 2.4.5. Hybrid Optical Processing 88 2.5. image Processing with Optics 89 2.5.1. Correlation Detection 89 2.5.2. Image Restoration 93 2.5.3. Image Subtraction 98 2.5.4. Broadband Signal Processing 98 2.6. Algorithms for Processing 103 2.6.1. Mellin-Transform Processing 104 2.6.2. Circular Harmonic Processing 105 2.6.3. Homomorphic Processing 107 2.6.4. Synthetic Discriminant Algorithm 108 2.6.5. Simulated Annealing Algorithm 112 2.7. Processing with Photorefractive Optics i 15 2.7.1. Photorefractive Eifect and Materials 115 2.7.2. Wave Mixing and Multiplexing 118 2.7.3. Bragg Diffraction Limitation 121 2.7.4. Angular and Wavelength Selectivities 122 2.7.5. Shift-Invariant Limited Correlators 125 2.8. Processing with Incoherent Light 131 2.8.1. Exploitation of Coherence 131 2.8.2. Signal Processing with White Light 135 2.8.3. Color Image Preservation and Pseudocoloring 138 2.9. Processing with Neural Networks 141 2.9.1. Optical Neural Networks 142 2.9.2. Holpfield Model 143 2.9.3. Inpattern Association Model 144 References 147 Exercises 148 Chapter 3, Communication with Optics 163 3.1. Motivation of Fiber-Optic Communication 163 3.2. Light Propagation in Optical Fibers 164 3.2.1. Geometric Optics Approach 164 3.2.2. Wave-Optics Approach 164 3.2.3. Other Issues Related to Light Propagating in Optical Fiber 168 3.3. Critical Components 184 3.3.1. Optical Transmitters for Fiber-Optic Communications — Semiconductor Lasers 184 Contents VI i 3.3.2. Optical Receivers for Fiber-Optic Communications 188 3.3.3. Other Components Used in Fiber-Optic Communications 192 3.4. Fiber-Optic Networks 192 3.4.1. Types of Fiber-Optic Networks Classified by Physical Size 193 3.4.2. Physical Topologies and Routing Topologies Relevant to Fiber-Optic Networks 193 3.4.3. Wavelength Division Multiplexed Optics Networks 193 3.4.4. Testing Fiber-Optic Networks 195 References 198 Exercises 198 Chapter 4. Switching with Optics 20! 4.1. Figures of Merits for an Optical Switch 202 4.2. All-Optical Switches 203 4.2.1. Optical Nonlinearity 205 4.2.2. Etalon Switching Devices 205 4.2.3. Nonlinear Directional Coupler 208 4.2.4. Nonlinear Interferometric Switches 211 4.3. Fast Electro-optic Switches: Modulators 219 4.3.1. Direct Modulation of Semiconductor Lasers 220 4.3.2. External Electro-optic Modulators 225 4.3.3. MEMS Switches Without Moving Parts 236 4.4. Optical Switching Based on MEMS 236 4.4.1. MEMS Fabrications 237 4.4.2. Electrostatic Actuators 238 4.4.3. MEMS Optical Switches 242 4.5. Summary 247 References 248 Exercises 250 Chapter 5. Transformation with Optics 255 5.1. Huygens- Fresnel Diffraction 256 5.2. Fresnel Transform 257 5.2.1. Definition 257 5.2.2. Optical Fresnel Transform 257 5.3. Fourier Transform 259 5.4. Wavelet Transform 260 5.4.1 Wavelets 260 5.4.2. Time-frequency Joint Representation 261 5.4.3. Properties of Wavelets 262 5.5. Physical Wavelet Transform 264 5.5.1. Electromagnetic Wavelet 264 5.5.2. Electromagnetic Wavelet Transform 266 5.5.3. Electromagnetic Wavelet Transform and Huygens Diffraction 260 5.6. Wigner Distribution Function 270 5.6.1. Definition 270 5.6.2. Inverse Transform 271 Vlll Contents 5.6.3. Geometrical Optics Interpretation 271 5.6.4. Wigner Distribution Optics 272 5.7. Fractional Fourier Transform 275 5.7.1. Definition 275 5.7.2. Fractional Fourier Transform and Fresnel Diffraction 277 5.8. Hankel Transform 279 5.8.1. Fourier Transform in Polar Coordinate System 279 5.8.2. Hankel Transform 281 5.9. Radon Transform 282 5.9.1. Definition 282 5.9.2. Image Reconstruction 283 5.10. Geometric Transform 284 5.10.1. Basic Geometric Transformations 288 5.10.2. Generalized Geometric Transformation 288 5.10.3. Optical Implementation 289 5.11. Hough Transform 292 5.11.1. Definition 292 5.11.2. Optical Hough Transform 293 References 294 Exercises 295 Chapter 6 Interconnection with Optics 299 6.1. Introduction 299 6.2. Polymer Waveguides 303 6.2.1. Polymeric Materials for Waveguide Fabrication 303 6.2.2. Fabrication of Low-Loss Polymeric Waveguides 305 6.3.2. Waveguide Loss Measurement 310 6.3. Thin-Film Waveguide Couplers 312 6.3.1. Surface-Normal Grating Coupler Design and Fabrication 312 6.3.2. 45° Surface-Normal Micromirror Couplers 326 6.4. Integration of Thin-Film Photodetectors 331 6.5. Integration of Vertical Cavity Surface-Emitting Lasers (VCSELs) 334 6.6. Optical Clock Signal Distribution 339 6.7. Polymer Waveguide-Based Optical Bus Structure 343 6.7.1. Optical Equivalent for Electronic Bus Logic Design 345 6.8. Summary 348 References 349 Exercises 351 Chapter 7 Pattern Recognition with Optics 355 7.1. Basic Architectures 356 7.1.1. Correlators 356 7.1.2. Neural Networks 357 7.1.3. Hybrid Optical Architectures 357 7.1.4. Robustness of JTC 362 7.2. Recognition by Correlation Detections 364 7,2.1. Nonconventional Joint-Transform Detection 364 Contents IX 7.2.2. Nonzero-order Joint-Transform Detection 368 7.2.3. Position-Encoding Joint-Transform Detection 370 7.2.4. Phase-Representation Joint-Transform Detection 371 7.2.5. Iterative Joint-Transform Detection 372 7.3. Polychromatic Pattern Recognition 375 7.3.1. Detection with Temporal Fourier-Domain Filters 376 7.3.2. Detection with Spatial-Domain Filters 377 7.4. Target Tracking 380 7.4.1. Autonomous Tracking 380 7.4.2. Data Association Tracking 382 7.5. Pattern Recognition Using Composite Filtering 387 7.5.1. Performance Capacity 388 7.5.2. Quantization Performance 390 7.6. Pattern Classification 394 7.6.1. Nearest Neighbor Classifiers 395 7.6.2. Optical Implementation 398 7.7. Pattern Recognition with Photorefractive Optics 401 7.7.1. Detection by Phase Conjugation 401 7.7.2. Wavelength-Multiplexed Matched Filtering 404 7.7.3. Wavelet Matched Filtering 407 7.8. Neural Pattern Recognition 411 7.8.1. Recognition by Supervised Learning 412 7.8.2. Recognition by Unsupervised Learning 414 7.8.3. Polychromatic Neural Networks 418 References 422 Exercises 423 Chapter 8 Information Storage with Optics 435 8.1. Digital Information Storage 435 8.2. Upper Limit of Optical Storage Density 436 8.3 Optical Storage Media 438 8.3.J. Photographic Film 438 8.3.2. Dichromated Gelatin 439 8.3.3. Photopolymers 439 8.3.4. Photoresists 440 8.3.5. Thermoplastic Film 440 8.3.6. Photorefractive Materials 441 8.3.7. Photochromic Materials 442 8.3.8. Electron-Trapping Materials 442 8.3.9. Two Photon-Absorption Materials 443 8.3.10. Bacteriorhodospin 444 8.3.11. Photochemical Hole Burning 444 8.3.12. Magneto-optic Materials 445 8.3.13. Phase-Change Materials 446 8.4. Bit-Pattern Optical Storage 446 8.4.1. Optical Tape 447 8.4.2. Optical Disk 447 8.4.3. Multilayer Optical Disk 448 8.4.4. Photon-Gating 3-D Optical Storage 449