Free-Space Laser Communications: Principles and Advances

0387286527......Page 1
Free-Space Laser\rCommunications......Page 4
Copyright Page\r......Page 5
Preface......Page 6
Contributors......Page 10
Table of Contents\r......Page 12
1. Introduction......Page 13
1.1. Brief History......Page 14
1.4. Limitations......Page 15
1.5. Basics of Operation......Page 16
2.2. Fundamental Limit of Light Detection......Page 17
2.3. BER for a Random Stochastic Communication Channel......Page 18
2.6. Coding for Atmospheric Channel......Page 19
References......Page 20
1. Introduction......Page 21
2.1. Extinction......Page 22
2.2. Molecular Extinction......Page 23
2.3. Molecular Transmittance Codes......Page 24
2.4. Aerosol Extinction......Page 25
2.5. Mie Theory......Page 27
2.6. Aerosol Models......Page 29
2.7. Atmospheric Attenuation of Laser Power......Page 31
3.1. Refractive Index Structure Parameter C2n......Page 32
3.2.1. PAMELA Model......Page 35
3.2.2. Gurvich Model......Page 40
3.2.4. Hufnagel-Valley Model......Page 42
3.2.6. Greenwood Model......Page 43
3.2.7. Other Thrbulence Models......Page 44
3.3.1. Free-Space Laser Beam Propagation......Page 45
3.3.2. Laser Beam Propagation in Optical Turbulence......Page 46
3.3.3. Scintillation Index and Aperture Averaging......Page 48
3.3.5. Bit Error Rate Determination for a Direct-Detection Binary Optical Communication Link......Page 52
Acknowledgments......Page 56
Calculate Flux Profile Relationships......Page 57
Change degrees Fahrenheit to Kelvin......Page 58
Calculate Monin-Obukhov Length L......Page 59
Estimate gradient for refractive index fluctuations......Page 60
Appendix B: Calculating Solar Iirradiance and Sensible Heat Flux......Page 61
focusing parameter......Page 62
Aperture-averaging Factor A......Page 63
References......Page 64
1. Introduction......Page 69
2.1. Communication Channel Characterization......Page 71
2.3. Link Analysis......Page 72
2.3.3. Bit Error Rate in Presence of Atmospheric Absorption and Scattering......Page 74
2.3.4. Example Numerical Results......Page 76
2.4. Optical Link Reliability......Page 82
3. Laser Communication Performance Prediction and Analysis Under Scintillation Conditions......Page 84
3.1. Scintillation index: Point Receiver and Aperture Averaged Variance......Page 85
3.1.3. Gaussian beam wave [14]......Page 87
3.2. Probability Density Function (pdf) Models......Page 88
3.3.1. Relationship between SNR and BER......Page 91
3.3.2. Why Atmospheric Turbulence Increases the Bit Error Rate?......Page 92
3.3.3. Bit-Error Rate Computation for OOK Modulation......Page 93
3.3.4. Bit-Error Rate Computation for Pulse Position Modulation(PPM) : Some Basics......Page 94
3.4. Probability of Fade......Page 95
4.1. Example I : Uplink (Spherical Wave/OOK)......Page 96
4.2. Example 2: Downlink (Plane Wave/OOK)......Page 99
4.3. Example 3: Horizontal: Terrestrial Link (Gaussian Beam Wave/OOK)......Page 101
4.4.1. Theory and Formulation of BER for PPM with Stretched Pulses for Pulse Position Modulation......Page 104
4.4.2. BET-Error-Rate (BER) and Slot Count Statistics\r......Page 107
4.4.3. The Impulse Response Function in the Case of Multiple Scattering......Page 108
4.4.4. Numerical Results......Page 109
4.4.5. BER Computation for Both Turbulence and Multiple Scattering Media......Page 110
5.2.1. Indoor Optical Communication......Page 112
5.2.2. Free-space Optical Interconnect......Page 113
6. Multiple Transmitters/Receivers Approach for Lasercomm......Page 114
7. Conclusion......Page 116
References......Page 117
1. Introduction......Page 121
1.1. Background......Page 123
1.3. Historical Perspective......Page 127
2.1. Carrier Characteristics......Page 129
2.2. Electromagnetic Signaling Options......Page 131
2.2.1. Overview of FSO Modulation Formats and Sensitivities......Page 132
2.2.1.1. On-Off-Keying (OOK)......Page 133
2.2.1.2. Differential-Phase-Shift-Keying (DPSK)......Page 134
2.2.1.4. M -ary Orthogonal Modulation......Page 135
2.2.1.5. M-ary Pulse-Position Modulation (M-PPM)......Page 137
2.2.1.6. M-ary Frequency-Shift Keying (M-FSK)......Page 139
2.3.1. Diffraction......Page 140
2.3.2. Optical Detection......Page 141
2.3.3. Technology Limitations......Page 142
2.3.4. Average and Peak Power Limited Transmitters......Page 143
2.3.5. Quantum Noise Limitations......Page 144
2.3.6. Quantum-limited Direct Detection (DD)......Page 147
2.3.7. Thermal Noise......Page 150
2.4. Example Sensitivities and Link Budget......Page 153
3. Transmitter Technologies......Page 154
3.1. Direct Modulation and Semiconductor Laser Sources......Page 155
3.1.1. Spectral Shaping......Page 156
3.2. Semiconductor Laser Structures......Page 158
3.3. Laser Wavelength Control......Page 159
3.4. Cavity-Dumped and Q-Switched Lasers......Page 161
3.5.1. Modulation......Page 162
3.5.2. Mach-Zehnder Modulator (MZM)......Page 163
3.5.2.1. MZM Phase Elements......Page 165
3.5.2.3. Extinction Ratio (ER)......Page 166
3.5.2.4. Extinction Ratio Characterization and Optimization......Page 167
3.5.2.5. MZM Drive Powerand Chirp Considerations......Page 169
3.5.2.6. Pulsed Waveform Generation......Page 171
3.5.3. High Power Optical Amplifier......Page 173
3.5.3.2. Amplifier Gain, Saturation, and Noise......Page 175
3.5.3.3. Amplifier Efficiency......Page 177
3.5.3.4. Polarization-Maintaining (PM) Fiber Amplifier Designs......Page 180
3.5.4. High-Efficiency Semiconductor Optical Amplifiers......Page 182
3.5.5. Arbitrary Waveforms and Variable-Duty-Cycle Signaling......Page 184
3.5.5.3. B) Transmitter ASE......Page 186
3.5.5.4. C) Nonlinear Impairments......Page 188
4.1. Direct Detection-PIN......Page 193
4.2. Direct Detection Avalanche-Photodiode (APD)......Page 195
4.3. Direct Detection-Photon Counting......Page 196
4.4. Coherent Homodyne Receivers......Page 197
4.5. Optically Preamplified Direct Detection......Page 198
5. Performance and Implementation Considerations......Page 201
5.1. Waveform and Filtering Considerations......Page 202
5.1.1. Symmetric Filtering......Page 204
5.1.2.1. Relaxed Filter Tolerances......Page 205
5.1.2.2. Reduced Sensitivity to Timing Jitter......Page 207
5.1.2.3. Combined Optical and Postdetection Filtering......Page 209
5.1.3. Optimized Multi-Rate Transceivers......Page 211
5.2. Differential Phase Shift Keying (DPSK)......Page 212
5.2.1. DPSK Wavelength Alignment Considerations......Page 213
5.2.2. Interferometer Stabilization......Page 215
5.2.3. Multi-Wavelength DPSK Receiver Options......Page 218
5.2.4. Reconfigurable DPSK Demodulators......Page 221
5.3. Hybrid Modulation Formats......Page 222
5.4. Demonstrated Communication Performance......Page 223
5.5. Applications: to the Moon and Beyond......Page 227
Acknowledgments......Page 230
Acronyms andAbbreviations......Page 232
References......Page 234
Symbols......Page 231
Free-space laser communications with adaptive optics: Atmospheric compensation experiments......Page 259
1. Introduction......Page 260
2. Adaptive Optics Architectures for Free-Space Optical Communication Systems......Page 261
3. Experimental System Arrangement and Components......Page 264
4.1. Tracking and Fast Beam Steering System......Page 267
4.2. Compensation of Atmospheric Wave-Front Tilt Distortions......Page 269
4.3. Laser Communication with Tip/Tilt Control......Page 270
5.1. SPGD Adaptive Optics System......Page 272
5.2. Temporal Behavior of the Received Power in the Tip/Tilt-Compensated Receiver System......Page 273
5.3. Wave-Front Control with the SPGD AO System......Page 274
5.4. SPGD Adaptive Transceiver System......Page 279
6. Summary and Conclusion......Page 280
References......Page 281
Optical networks, last mile access and applications......Page 285
1.1. Types of FSO Systems for Different Network Architectures......Page 286
1.2.1. Optical Wireless in Ring Architecture......Page 288
1.2.2. Optical Wireless in Star Architecture......Page 289
1.3. Connecting to the Backbone......Page 290
2. FSO Applications......Page 291
2.1. Short Range Aapplications and Last Mile Access......Page 293
2.2. Long Range Applications......Page 296
2.3. Space Applications (Aircraft and Satellites)......Page 299
3.1. Line of Sight......Page 301
3.2. Reliability and Availability......Page 303
3.3. Different FSO Techniques for the Last Mile......Page 306
3.3.2. FSO System for 300 m......Page 307
3.4.1. Multimedia Applications......Page 308
3.4.2. FSO Network for a Small City......Page 309
4. Summary......Page 312
References......Page 313
Communication techniques and coding for atmospheric turbulence channels......Page 315
1. Introduction......Page 316
2. Modeling of Optical Communication through Atmospheric Turbulence......Page 317
2.2. Spatial and Temporal Coherence of Optical Signals through Turbulence......Page 318
2.3.1. Marginal Distribution of Fading......Page 320
2.3.2. Joint Spatial and Temporal Distributions of Fading......Page 321
3. Maximum-Likelihood Detection of On-Off Keying in Thrbulence Channels......Page 322
3.1. Symbol-by-Symbol Maximum-Likelihood Detection......Page 323
4.1. Maximum-Likelihood Diversity Detection on Turbulence Channels......Page 325
4.2. Numerical Simulationfor Dual Receivers......Page 327
4.3. Summary......Page 328
5.1.1 . Joint Temporal Distribution for Turbulence Induced Fading......Page 329
5.1.3. Burst Error Distribution for Symbol-by-Symbol Detection......Page 330
5.1.4. Sub-Optimal Per-Survivor Processing for MLSD......Page 333
5.2. Pilot-Symbol Assisted Detectionfor Correlated Turbulent Free-Space Optical Channels......Page 336
5.2.1. Pilot-Symbol Assisted Maximum-Likelihood Detection......Page 337
5.2.2. Pilot-Symbol Assisted Symbol-by-Symbol Detection with Variable Threshold......Page 339
5.3. Experimental Demonstration on Temporal Domain Techniques......Page 340
6. Performance Bounds for Coded Free-Space Optical Communication Through Atmospheric Turbulence......Page 344
6.1. Pairwise Codeword-Error Probability Bound......Page 345
6.2.1. Block Codes......Page 347
6.3. Convolutional Codes......Page 348
6.3.1. Turbo Codes......Page 350
6.4. Numerical Simulation Results......Page 351
6.5. Summary......Page 353
Conclusions......Page 354
References......Page 355
Optical communications in the mid-wave IR spectral band......Page 358
1. Introduction......Page 359
2. Atmospheric Modeling......Page 360
2.1. Atmospheric Turbulence......Page 363
2.1.1. Rytov Variance......Page 364
2.1.2. Coherence Length......Page 365
2.2. Beam Diameter......Page 366
2.3. Direct Detection SNR......Page 368
2.4. Large Scale and Small Scale Turbulence - Spherical Waves......Page 369
2.5. Bit Error Rate (BER) and Minimum SNR......Page 370
3.1. Semiconductor Based Lasers......Page 373
3.1.3. Quantum Cascade Lasers......Page 374
3.1.4. Solid-State Lasers......Page 375
3.2. Nonlinear Frequency Converters......Page 376
3.2.2. PPLN OPOs......Page 380
3.2.3. Oscillation Threshold Calculations......Page 381
4.1. Dember Effect Detectors......Page 383
5. Data Communications in the Mid-IR......Page 385
5.1. Weapon Code Transmission in MWIR......Page 386
5.1.2. Transceiver Design Approach......Page 387
5.1.3. Experimental Results......Page 391
5.2. Image Transmission in MWIR using an OPO......Page 396
References......Page 400
1. Introduction......Page 403
2. High Frequency Analog and Digital Modulation......Page 404
3. Experimental Apparatus......Page 406
3.1. Satellite TV Transmission Using a QCL-Based FSO Link......Page 412
References......Page 415
1. Introduction......Page 417
2.2. Smoke Extinction Model......Page 418
3.1. Compact RF-Driven Laser......Page 421
3.2. Stark-Effect Modulator......Page 422
3.3. Dielectric Waveguide Modulator......Page 423
3.4. AC Biasing Method......Page 424
4. Experimental Results......Page 425
References......Page 427