1、 AEROSPACE INFORMATION REPORT A Guideline for Application of RF Photonics to Aerospace Platforms SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirely voluntary, and its applic
2、ability and suitability for any particular use, including any patent infringement arising therefrom, is the sole responsibility of the user.” SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and s
3、uggestions. Copyright 2005 SAE International All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of SAE. TO PL
4、ACE A DOCUMENT ORDER: Tel: 877-606-7323 (inside USA and Canada) Tel: 724-776-4970 (outside USA) Fax: 724-776-0790 Email: custsvcsae.org SAE WEB ADDRESS: http:/www.sae.org Issued 2005-06 AIR5601 FOREWORD This document was developed by the SAE AS-3A-2 RF/Analog Technology Task Group under AS-3 Fiber O
5、ptics and Applied Photonics and AS-3A Applications. The formation of this task group was approved at the fall meeting of the SAE AS-3 committee in October 2002. While RF photonics technology can potentially provide enormous benefits to future aerospace platforms, the technology is significantly diff
6、erent from conventional RF technology and requires engineers to think in somewhat new terms and adapt to the peculiarities of the medium. Establishment of guidelines for the application of RF photonics technology will assist avionics systems suppliers and customers in the design, development, and te
7、sting of future systems which incorporate photonics networks that include analog RF signal transmission. This document is dedicated to that goal. There are many contributors to be recognized for their efforts in developing this document and the AS-3 Fiber Optics and Applied Photonics Committee is gr
8、ateful for everyones contributions. Unfortunately we cannot list the names of individuals in this document. The intended audience for this work is new engineering graduates, experienced engineers who are new to fiber optics and managers who are new to fiber optics or have been away from day-to-day e
9、xposure to fiber optics for a while. Realizing that the SAE is an international organization and that information published by the SAE is available worldwide, the information contained herein is limited to that which is also available independently from the various companies which provided it. This
10、document only serves to gather and collate the information from the many various sources to facilitate the understanding and utilization of RF/Analog signals transmitted over fiber-optic networks. SAE AIR5601 - 2 - This task group was formed with an open invitation to professionals in government and
11、 at major platform developers and suppliers of photonics systems and components. Beginning with a few contacts from SAE and existing programs, the call went out: who do you know with RF photonics expertise? From these new contacts: who do you know? So I call this task group the “who do you know, who
12、 do you know group”. These are professionals known by their piers as experts in the field of RF photonics technology. They have worked on a volunteer basis with the support of their company or organization to develop a document that defines the current art of RF photonics. I am indebted to them and
13、their organizations for their dedication to this effort. SAE AIR5601 - 3 - TABLE OF CONTENTS 1. SCOPE 9 2. REFERENCES.9 2.1 List of Acronyms.9 3. RF PHOTONICS AEROSPACE APPLICATIONS AND ADVANTAGES .15 3.1 Advantages of Photonics in RF Systems .16 3.1.1 Electromagnetic Interference (EMI) Resistance.1
14、6 3.1.2 Superior Phase Stability.17 3.1.3 Extremely Low Optical Transmission Loss Leading to Platform Independence 17 3.1.4 Small Size/Light Weight Cabling17 3.1.5 Extremely Wide Bandwidth 17 3.1.6 Growth Capability and Scalability.18 3.1.7 Survivability and Vulnerability 18 3.2 Signal Distribution
15、and Delay Applications.18 3.2.1 Antenna Remoting and Signal Distribution 18 3.2.2 RF Delay Lines.20 3.2.3 Use of RF Delay Lines for Radar Testing or False Target Generation 22 3.2.4 Use of Wavelength Division Multiplexing to Replace RF Switching.22 3.2.5 True Time Delay Beamforming 25 3.3 Signal Pro
16、cessing and Generation Applications 26 3.3.1 RF Signal Generation Using Photonic Processes26 3.3.2 RF-Photonic Methods for Frequency Conversion 27 3.3.3 RF-Photonic Transversal Filters.29 3.3.4 RF-Photonic Sampling of Analog Waveforms30 3.3.5 Use of RF Photonics in Digital Systems.31 3.4 Summary33 4
17、. RF PHOTONICS SYSTEMS CONSIDERATIONS.34 4.1 Frequency Bands of RF Systems 34 4.2 RF Systems Architecture with Insertion of Photonics Technologies35 4.2.1 Suitability of Multi-Mode Optical Fiber for RF-Photonic Systems.35 4.2.1.1 Characteristics of Multi-Mode Optical Fibers .35 4.2.1.2 Performance L
18、imitations of RF-Photonic Links with Multi-Mode Optical Fibers.36 4.2.1.3 Use of Multi-mode Fiber with Multi-Mode Photonic Devices40 4.2.2 Selection of Optical Wavelength for RF-Photonic System .41 4.2.3 RF-Photonic Signal Distribution and Switching Architectures43 4.2.4 Considerations for Multiplex
19、ing of Analog and Digital Signals.46 4.24.1 Optical Non-Linearities in Fiber47 4.3 Modulation Techniques for RF Photonic Applications48 4.3.1 Intensity Modulation .49 4.3.2 Frequency Modulation49 4.3.3 Phase Modulation 50 4.3.4 Subcarrier Multiplexing (SCM) .50 SAE AIR5601 - 4 - 4.3.5 Wavelength Div
20、ision Multiplexing (WDM) 50 4.4 Summary51 5. LINK PERFORMANCE MEASUREMENT PARAMETERS51 5.1 Linearity51 5.1.1 Gain Compression .52 5.1.2 Harmonic and Intermodulation Distortion.53 5.1.3 Phase Linearity and Latency53 5.2 Noise Figure.54 5.3 Dynamic Range56 5.3.1 Signal to Noise Dynamic Range (Compress
21、ion Dynamic Range) .56 5.3.2 Spur-Free Dynamic Range 57 5.4 Optical Return Loss59 5.5 Summary61 6. LINK COMPONENTS 63 6.1 Active Components63 6.1.1 Direct Versus External Modulation.63 6.1.2 Laser Selection 68 6.1.3 Modulator Selection .70 6.1.4 Detector Selection88 6.1.5 Amplifiers .89 6.1.6 Active
22、 Component Summary .99 6.2 Passive Components .99 6.2.1 Fiber Selection .99 6.2.2 Cable and Fiber Buffer(s) Selection.101 6.2.3 Connector Selection.102 6.2.4 Coupler and Multiplexer Selection .107 6.2.5 Switches.110 6.2.6 Passive Component Summary.112 7. ENVIRONMENTAL CONSIDERATIONS.112 7.1 Introduc
23、tion 112 7.2 Temperature.112 7.2.1 Storage Temperature, Low-Side 113 7.2.2 Operational Temperature, Low-Side, Outside Enclosure.113 7.2.3 Operational Temperature, Low-Side, Inside Enclosure .113 7.2.4 Storage Temperature, High-Side .113 7.2.5 Operational Temperature, High-Side, Outside Enclosure113
24、7.2.6 Operational Temperature, High-Side, Inside Enclosure.114 7.2.7 Effects of Temperature on Analog Fiber Optic Links and Mitigation of Those Effects.115 7.3 Vibration.115 7.3.1 Operation Through Vibration115 7.3.2 Types of Vibration 116 7.3.3 Connector Vibration Standards116 SAE AIR5601 - 5 - 7.3
25、.4 Module Vibration Limits117 7.3.5 Effects of Vibration on Analog Fiber Optic Links118 7.4 Mechanical Shock118 7.4.1 Connector Shock118 7.4.2 Transceiver Shock .118 7.4.3 Effects of Shock .118 7.5 Contamination Exposure119 7.6 Out Gassing .119 7.7 Radiation120 7.8 Additional Environmental Effects .
26、120 7.9 Comparison to Commercial Standards 120 7.10 Summary - Environment 121 8. LIFE CYCLE AND LOGISTICS CONSIDERATIONS.122 8.1 Safety.122 8.1.1 Eye Safety123 8.1.2 Chemical 124 8.1.3 Electrical/RF.124 8.1.4 Glass124 8.2 Cleaning.125 8.2.1 Swabs and Wipes 125 8.2.2 Fluids126 8.2.3 Flushing Apparatu
27、s 127 8.2.4 Air Cleaning/Canned Air.127 8.3 Testing .127 8.3.1 Insertion Loss.128 8.3.2 Return Loss129 8.3.3 End Face Geometry.130 8.3.4 OTDR (Optical Time Domain Reflectometer).131 8.4 Installation136 8.5 Restoration.136 8.6 Reliability137 8.6.1 Optical Degradation Mechanisms 137 8.6.2 Reliability,
28、 Maintainability and Built-In Test (R, M and BIT) .140 8.6.3 Subcontractor and Supplier Reliability and Maintainability Requirements .140 8.6.4 Reliability, Maintainability and BIT Design Reviews.140 8.6.5 Reliability Critical Items140 8.6.6 Spares Reliability Provisions140 8.6.7 Failure Reporting,
29、Analysis and Corrective Action System (FRACAS)140 8.6.8 Failure Reporting140 8.6.9 Failure Analyses.141 8.6.10 Corrective Actions141 8.6.11 Reliability Math Models, Allocations and Predictions.141 8.6.12 Failure Modes, Effect and Critical Analyses (FMECA).141 8.6.13 Part Level Stress Analysis .142 8
30、.6.14 Maintainability and BIT Analyses .142 8.6.15 Environmental Effects Analysis142 8.6.16 Environmental Stress Screening (ESS) .142 SAE AIR5601 - 6 - 8.6.17 Thermal Survey143 8.6.18 Reliability Development Test (RDT).143 8.6.19 COTS/NDI (RDT) .143 8.6.20 RDT Requirements 143 8.6.21 Maintainability
31、 Demonstrations 143 8.6.22 R, M and BIT Evaluations 143 8.6.23 Reliability and Maintainability Review Board (RMRB)143 8.6.24 Qualification .144 8.7 Maintainability 144 8.8 Supportability .144 8.8.1 Training 145 8.8.2 Special Test Equipment .146 8.8.3 Tool Kits .146 8.9 Summary - Life Cycle and Logis
32、tics.150 9. SUMMARY, CONCLUSIONS AND RECOMMENDATIONS150 9.1 Key Challenges for RF Photonics 151 9.1.1 Laser Modulator Loss.151 9.1.2 Dynamic Range151 9.1.3 Signal Fidelity.151 9.1.4 Noise152 9.1.5 Signal Latency152 9.1.6 Temperature and Vibration 152 9.2 Conclusions and Recommendations152 9.3 The Fu
33、ture: An All-Optical Receiver Architecture. .153 10. KEY WORDS .154 FIGURE 1 Overview of Basic Modulation Process 16 FIGURE 2 Typical Configuration Showing Centralized RF Processing .18 FIGURE 3 Typical Fiber-Optic Towed Decoy Configuration19 FIGURE 4 Schematic of Multi-Channel Fiber-Optic Delay Lin
34、e.20 FIGURE 5 Four-channel Fiber-optic Network with Signal Replication and Delays21 FIGURE 6 Basic WDM Architecture Used as a RF Switch23 FIGURE 7 Staged WDM Network Configuration .24 FIGURE 8 Photonic Heterodyning Within a Photodetector to Produce RF Tones 26 FIGURE 9 Illustration of three approach
35、es for accomplishing frequency conversion with RF-photonic links: (a) electronic conversion, (b) dual-modulator link, (c) optical-heterodyned link 28 FIGURE 10 Illustration of a Generic RF-photonic Filter.29 FIGURE 11 Transmission Loss in Single-Mode and Graded-Index 62.5/125-Micrometer Optical Fibe
36、rs .35 FIGURE 12 Fiber Link Response Comparison 37 FIGURE 13 100 m Multi-Mode Link S21 for Various Fiber/Launch Configurations .38 SAE AIR5601 - 7 - FIGURE 14 Various RF-photonic signal distribution architectures involving (a) switched point-to-point links, (b) optical wavelength division multiplexi
37、ng of signals, (c) point-to-multipoint links with wavelength selection, and (d) data bus ring configuration with wavelength selection .45 FIGURE 15 Definition of an Intensity-Modulation Direct-Detection (IMDD) Analog Optical Link 64 FIGURE 16 Electrode configurations for EO modulation with (a) x-cut
38、 and (b) z-cut LiNbO3crystal.71 FIGURE 17 Schematic drawing of a Mach-Zehnder interferometer 73 FIGURE 18 Relative modulation efficiency versus modulator length at different optical propagation losses for (a) MZMs and (b) EAMs .77 FIGURE 19 RF equivalent circuit model for lumped-element EAMs. The sa
39、me model can also work for QCSE-type lumped-element MZMs by replacing Rowith an open-circuit (or setting Ro=) 78 FIGURE 20 A schematic diagram to show the operation of a continuous traveling wave modulator 82 FIGURE 21 (a) asymmetric strip line (ASL) configurations on x-cut and z-cut LiNbO3crystals.
40、 (b) Co-planar waveguide (CPW) configurations on x-cut and z-cut LiNbO3crystals.84 FIGURE 22 Schematic diagram to show the segmented traveling-wave electrode design.87 FIGURE 23 20 GHz Photoreceiver (photo courtesy of Bookham Technology, plc).89 FIGURE 24 MMIC implementation of a 2 to 20 GHz LNA wit
41、h 10 dB of gain and an NF of less than 4 dB. The die measures 3.15 by 1.78 mm and is 0.1 mm thick. .91 FIGURE 25 Butt Joint Connection .103 FIGURE 26 Expanded Beam Connection104 FIGURE 27 Diamond AVIM .105 FIGURE 28 Examples of Multi-Channel Connectors .106 FIGURE 29 Cooling Methods for Avionics Mod
42、ules 114 FIGURE 30 Power Spectral Density for Random Vibration (From MIL-STD-1344).117 FIGURE 31 Insertion Loss Procedure .129 FIGURE 32 Example End Face Geometry 131 FIGURE 33 Nominal Link Reflections132 FIGURE 34 Example Showing “Loud” Reflections 133 FIGURE 35 Example Showing Lossy Kinks 134 FIGU
43、RE 36 Example of a Dirty Connector 134 FIGURE 37 Example of a Connector With a Break .135 FIGURE 38 Installation Tools 147 FIGURE 39 Inspection Tools .147 FIGURE 40 Cleaning Tools .148 FIGURE 41 Termination Tools.148 FIGURE 42 Polishing Tools.149 FIGURE 43 Repairing Tools 149 FIGURE 44 Faultfinding
44、Tools.150 FIGURE 45 Optical Receiver Concept.153 SAE AIR5601 - 8 - TABLE 1 RF Frequency Band Designations .34 TABLE 2 Best Reported RF Performance (Measured) of Fiber-Optic Links .67 TABLE 3 Comparison of Various Modulators 87 TABLE 4 List of Applicable Military Standards 121 FORMULA 1 Mach-Zehnder
45、Modulator Output .27 FORMULA 2 Electrical Current Produced by Photo Detector27 FORMULA 3 Sum and Difference Products of the LO and RF Frequencies .28 FORMULA 4 The 1-db Compression Output Power52 FORMULA 5 The 1-db Compression Input Power.52 FORMULA 6 The Intermodulation Distortion Products 53 FORMU
46、LA 7 Noise Figure.54 FORMULA 8 The Link Output Noise due to Laser RIN .54 FORMULA 9 The External Modulation Link output Noise55 FORMULA 10 The Link Noise Figure 56 FORMULA 11 Compression Dynamic Range56 FORMULA 12 Signal-to-Noise Dynamic Range 57 FORMULA 13 Spur-Free Dynamic Range.57 FORMULA 14 Link
47、 Gain 65 FORMULA 15 Direct Modulation Link Gain .66 FORMULA 16 Modulator Slope Efficiency.66 FORMULA 17 Lithium Niobate Electro-Optic Coefficients.70 FORMULA 18 Mach-Zehnder Modulator Optical Intensity Transmission 73 FORMULA 19 Intensity Transmission for Voltage-Induced Phase Difference.74 FORMULA
48、20 Electro-Absorption Modulator Transfer Function74 FORMULA 21 Electro-Absorption Modulator Small-Signal Modulation Efficiency.74 FORMULA 22 Electro-Absorption Modulator Equivalent V Pi .75 FORMULA 23 Modulator Optical Insertion Loss76 FORMULA 24 Modulator Frequency Response 79 FORMULA 25 The 3-db M
49、odulation Bandwidth.79 FORMULA 26 The Microwave Voltage on the Waveguide81 FORMULA 27 Absolute Value of the Modulator Frequency Response .82 FORMULA 28 The Effective Microwave Velocity Index.83 FORMULA 29 Lithium Niobate Modulator Frequency Response 85 FORMULA 30 Lithium Niobate Microwave Loss Coefficients85 FORMULA 31 Noise Factor.90 FORMULA 32 Vibration Power Spectral Density Acceleration 116 SAE AIR5601 - 9 - 1. SCOPE: This SAE Aerospace Information Report (AIR) is devoted to the challenges of applying optics to new advanced RF analog systems only; digital data link applications ar
