Optical-Polymer and Polymer-Clad- Silica-Fiber Data Buses for Vehicles and Airplanes Principles, Limits and New Trends

Transcription

1 Optical-Polymer and Polymer-Clad- Silica-Fiber Data Buses for Vehicles and Airplanes Principles, Limits and New Trends Otto Strobel, Daniel Seibl, Jan Lubkoll, Uwe Strauß

2 Optical Transmission Optical Detector Optical Fiber Optical Transmitter throughout the Ages 2006 N.N., Hochschule Esslingen 2

3 Contents Introduction to Automotive Systems MOST: Media Oriented Systems Transport Principle Considerations Components for fiber-optic systems o System-relevant characteristics of fibers, transmitters and detectors and their limitations Future technologies for Automotive Systems Alternative components to overcome conventional limitations High speed optical data buses for automotive applications Limits and future applications of high-speed automotive data buses in vehicles and airplanes 2006 N.N., Hochschule Esslingen 3

4 Different Data Bus Technologies in Vehicles MOST Media Oriented Systems Transport MOST: Media Oriented Systems Transport Network for Multimedia Data LIN: Local Interconnect Network Communication of sensors and actuators CAN: Controller Area Network Communication of ECUs 2006 N.N., Hochschule Esslingen 4

5 Optical Data Bus Technologies for Automotive Applications Polymer Optical Fiber POF Media Oriented System Transport MOST Fiber-Optic Transceiver FOT (LED, Si-photodiode) in each subscriber 2006 N.N., Hochschule Esslingen 5

6 Media Oriented Systems Transport Standards based upon the ISO-OSI layer model 2006 N.N., Hochschule Esslingen 6

7 MOST Physical Layer Components Component FOT CONTROL UNIT Device Pigtail is integrated in ECU Function: MOST Device e.g.: CD-Player, Amplifier PIGTAIL Connector FOT is integrated Function: Represents the interface to the fiber Consists of two devices: Fiber optical Transmitter & Receiver PMMA fibers with 1 mm core diameter 2006 N.N., Hochschule Esslingen 7

8 Principle Considerations Optical Detector Optical Fiber Optical Transmitter 2006 N.N., Hochschule Esslingen 8

9 Advantages of Fiber-Optic Systems Low attenuation High bandwidth Low weight and small size Non-sensitivity against electromagnetic interference Electrical isolation Low crosstalk Transmission capacity = Bandwidth-length product: B L = Max! 2006 N.N., Hochschule Esslingen 9

10 Demands on Optical Fibers Proper Waveguiding Low loss of optical power Low dispersion of optical signals Large temperature range operation Non-sensitivity against distortions 2006 N.N., Hochschule Esslingen 10

11 Attenuation Coefficient Versus Wavelength of Glass Fibers Absorption, Demand: OH - : SiO 2 = 1 ppb = 10-9 Attenuation Coefficient α Absorption P 1 ~ S λ 4 Rayleigh Scattering Absorption α = 10dB lg L P P 0 Wavelength λ 2006 N.N., Hochschule Esslingen 11

12 Spectral Attenuation of Glassfibers and Optoelectronic Devices Attenuation Today < 0.2 db/km Optoelectronic Devices Wavelength Light Sources Photodiodes 2006 N.N., Hochschule Esslingen 12

13 Attenuation Coefficient of a PMMA Fiber 2006 N.N., Hochschule Esslingen 13

14 Polymer Optical Fiber (PMMA) Low price Robustness Simple connector fitting Attenuation between 0.2 and 0.4 db/m for red LEDs o Depends on the changing wavelength of the LED between -40 C and +85 C operating temperature 2006 N.N., Hochschule Esslingen 14

15 Light Guidance in an Optical Waveguide Cladding Material n 2 Air n = 1 δ δ δ C Fiber Axes Core Material n 1 > n 2 Numerical Aperture: A N = nsinδ = n 2 1 n 2 2 Cladding Material n N.N., Hochschule Esslingen 15

16 Transmitter and Receiver Pulse Beginning of Fiber End of Relative Power t 1, t 2 (FWHM, full width at half maximum). Time 2006 N.N., Hochschule Esslingen 16

17 Mode Dispersion of Optical Fibers Different transit times of optical pulses for different modes n Cladding < n Core Total internal reflection n Core Pulsebroadening 2006 N.N., Hochschule Esslingen 17

18 Pulse Development in an Optical Fiber Input pulses Output pulses after length L i B L = Max? 2006 N.N., Hochschule Esslingen 18

19 Fiber Types Cross Section Refraction Index Propagation of Light g g const const Multimode Stepindex Fiber Multimode Graded Index Fiber Monomode Fiber Optical Path Length: g = n L 2006 N.N., Hochschule Esslingen 19

20 Typical Communication Glassfibers and Woman Hair Multimode Fiber Stepindex Graded Index Singlemode Fiber 2006 N.N., Hochschule Esslingen 20

21 Polymer- and Glassfibers Glassfibers Hair 2006 N.N., Hochschule Esslingen 21

22 Material Dispersion Different Transit Times of Optical Pulses for different Wavelengths Pulsebroadening B L = Max? 2006 N.N., Hochschule Esslingen 22

23 Fiber Types Type Profile Size Attenuation Bandwidth-Length Product Plastic Step 950/1000 µm 0,2 db/m < 100 MHz m Fiber Index PCS Step µm 6 db/km < 10 MHz km Fiber Index Multimode Step Glass Index > 100 µm 3-5 db/km 20 MHz km Multimode Graded 50/125 µm 2 db/km (0.85 µm) 500 MHz km Glass Index 0,4 db/km (1,3 µm) 0,2 db/km (1,55 µm) Monomode 5-10 µm > 100 Gbit km/s Glass 2006 N.N., Hochschule Esslingen 23

24 Spectral Attenuation of different Fibers 2006 N.N., Hochschule Esslingen 24

25 Principle Considerations Optical Detector Optical Fiber Optical Transmitter 2006 N.N., Hochschule Esslingen 25

26 Demands on Optical Transmitters High Optical Output Power Small Electric Input Power Wavelength in proper Range Small Spectral Size Low Beam Divergence High Speed Modulation Injection Modulation Capability Small Size Reliability 2006 N.N., Hochschule Esslingen 26

27 Absorption and Emission E 2 E 1 = E = h f = h c λ Energy Absorption spontaneous Emission stimulated 2006 N.N., Hochschule Esslingen 27

28 Optical Power versus Injection Current of an LED 2006 N.N., Hochschule Esslingen 28

29 Farfield Characteristic of an LED P ~ cosδ Direction of observation Irradiant Surface 2006 N.N., Hochschule Esslingen 29

30 Modulation Performance at Low and High Frequencies Low Frequency High Frequency 2006 N.N., Hochschule Esslingen 30

31 Spectral Width of an LED E E 2 1 = E = h f h c = λ E h f λ: Spectral Width (FWHM, Full Width at Half Maximum) 2006 N.N., Hochschule Esslingen 31

32 Optical Power versus Injection Current of a Semiconductor Laser Light Amplification by Stimulated Emission of Radiation Optical Power mw ma Injection Current 2006 N.N., Hochschule Esslingen 32

33 Farfield Characteristics of a Laser Diode Vertical (Parallel oriented to Current Flow) Horizontal (Perpendicularly oriented to Current Flow) 2006 N.N., Hochschule Esslingen 33

34 Rel. Optical Power Spectral width of LED and Laser E E 1 = E = h f = h c λ 2 E h f Wavelength 2006 N.N., Hochschule Esslingen 34

35 Vertical Cavity Surface Emitting Laser (VCSEL) mw Optical Power ma Injection Current Wavelength nm 2006 N.N., Hochschule Esslingen 35

36 Light Sources for Fiber-Optic Systems 2006 N.N., Hochschule Esslingen 36

37 Principle Considerations Optical Detector Optical Fiber Optical Transmitter 2006 N.N., Hochschule Esslingen 37

38 Demands on Optical Detectors High sensibility Spectral responsitivity of a Si pin-photodiode Low noise Small size High bandwidth 2006 N.N., Hochschule Esslingen 38

39 Photon Absorption and Carrier Generation R: Load Resistor 2006 N.N., Hochschule Esslingen 39

40 Responsivity versus Wavelength of various Semi-Conductor Materials E 2 E 1 = E = h f = h c λ h f E 2006 N.N., Hochschule Esslingen 40

41 Historical pn-photodiode and Electric Field Distribution Minimum Field Maximum Field 2006 N.N., Hochschule Esslingen 41

42 pin-photodiode and Electric Field Distribution Field Flattening Intrinsic Zone 2006 N.N., Hochschule Esslingen 42

43 Avalanche Photodiode (APD) and Electric Field Distribution Very High Electric Field Highly Doped Area Field Flattening 2006 N.N., Hochschule Esslingen 43

44 System Considerations Optical Detector Optical Fiber Optical Transmitter 2006 N.N., Hochschule Esslingen 44

45 System Integration 2006 N.N., Hochschule Esslingen 45

46 System Modulation Transfer Function and Data Signal B f c f c : Cut-off Frequency B: Bandwidth f 25 Mbit/s-Signal 2006 N.N., Hochschule Esslingen 46

47 Limitations of Polymer Fiber Networks Best solution in terms of costs for state of the art systems 1-mm-Core-Diameter POF, Red LED, Large Area Si-Photodiode Most important component limitations Maximum bandwidth of LED < 100 MHz Maximum temperature of PMMA Fiber 85 C Minimum attenuation (for red LED) of PMMA Fiber 0.4 db/m Bandwidth-length product B. L 3000 MHz. m (e.g.150 MHz after 20 m) Maximum bandwidth of typ. 1 mm 2 area Si-Photodiode 100 MHz Resulting system limitations Maximum data rate 150 MBit/s Maximum temperature range: 40 C to +85 C Maximum link length < 10 m 2006 N.N., Hochschule Esslingen 47

48 Restrictions by POF Networks Conclusions POF-Systems are not suited for data ranges in Gbit/s region, temperature demands up to 125 C, and link length > 20m necessary for future use in Sensor systems for safety applications Engine management systems Drive by wire systems Video processing for driver assistance and autonomous driving Therefore alternative solutions have to be found! 2006 N.N., Hochschule Esslingen 48

49 Future Technologies based on PCS Fibers and VCSELs Polymer-Cladded Silica fibers (PCS) with 200 µm core Minimum attenuation at 850 nm db/m After 20 m 98% (16 % for PMMA fibers) Maximum temperature: 125 C No bandwidth restrictions, B. L = 20 GHz. m After 20 m 1 GHz (150 MHz for PMMA fibers) polymer cladding 2006 N.N., Hochschule Esslingen 49

50 VCSEL Transmitter Vertical Cavity Surface Emitting Laser (VCSEL) at 850 nm Maximum bandwidth > 1 GHz Low injection current Coupling efficiency > 90% Maximum temperature: 125 C 2006 N.N., Hochschule Esslingen 50

51 Receiver Si pin-photodiode Small area (due to small PCS fiber core) low junction capacity Maximum bandwidth 1.5 GHz Low coupling loss High spectral sensitivity at 850 nm (comp. to PMMA-Syst. at 650 nm.: 1.3 db gain) 2006 N.N., Hochschule Esslingen 51

52 Passive Star Network for Safety- Relevant Systems PCS Fiber-optic star coupler Planar optical waveguides for star coupler structures 200 µm x 200 µm waveguides 2006 N.N., Hochschule Esslingen 52

53 Planar Bi-Directional Transceiver Integration in planar flat printed circuits 2006 N.N., Hochschule Esslingen 53

54 Concepts for Aircrafts Lightning strike Diehl Aerospace 2006 N.N., Hochschule Esslingen 54

55 Lightning Strike Nowadays aircrafts have a metal fuselage Faraday s cage effect good passive lightning protection granted heavy, high fuel consumption Future aircrafts are using more and more carbon fiber fuselage less weight less fuel consumption Attention: Carbon fiber skin! less/no Faraday s cage effect more protections needed 2006 N.N., Hochschule Esslingen 55

56 Airbus Cabin Management Systems Cabin Management Carbon fiber skin Diehl Aerospace 2006 N.N., Hochschule Esslingen 56

57 Optical Data Bus for Airbus A320 (A30X) or Boeing 787 (new 737) System Features: 10 MBit/s, 100 m, 8 by 8 ports PCS Fibers PCS Fibers Transceiver: Tx: Transmitter Rx: Receiver PCS Star Coupler Diehl Aerospace 2006 N.N., Hochschule Esslingen 57

58 Actual Solutions Data rate: 10 MBit/s Operating temperature: -40 C +85 C Distance between two nodes: 100 m (50 m optical star 50 m) Passive star network 2006 N.N., Hochschule Esslingen 58

59 POF Simple connector fitting Low price Robustness 650 nm attenuation of ~0.19 db/m 2006 N.N., Hochschule Esslingen 59

60 POF - Problems high attenuation of star coupler (~ 13 db) fiber (~ 19 db) connectors (~ 2 db) receiver sensitivity: ~ -28 dbm Optical power budget POF 2006 N.N., Hochschule Esslingen 60

61 Polymer-Clad-Silica Fibers Combines the POF advantages with the standard silica fiber advantages Low attenuation ( db/m at 850 nm) Good connector fitting Robust 200 µm step index fiber 2006 N.N., Hochschule Esslingen 61

62 Vertical-Cavity Surface-Emitting Laser (VCSEL) Small output beam divergence high coupling efficiency Low current consumption Small spectral width 850 nm VCSEL higher receiver relative sensitivity 2006 N.N., Hochschule Esslingen 62

63 VCSEL and PCS Higher output power above 0 dbm Better receiver sensitivity about -30 dbm Low fiber attenuation 30 db link budget (incl. 3 db margin) about 0.8 db / 100 m instead of 19 db / 100 m (POF) Additional design options, like reflexive optical star Less fibers needed, less weight 2006 N.N., Hochschule Esslingen 63

64 VCSEL and PCS dbm receiver sensitivity 2006 N.N., Hochschule Esslingen 64

65 Aircraft Related Conclusions More and more carbon-fiber fuselage components stronger lightning influences more problems in signal transmission Adequate optical solutions have to be used simple point-to-point connections POF + LED complex optical networks over the whole plane PCS + VCSEL 2006 N.N., Hochschule Esslingen 65

66 Prototype Transmission Star Coupler 2006 N.N., Hochschule Esslingen 66

67 Transmitted Data Signal 2006 N.N., Hochschule Esslingen 67

68 Application Roadmap for Automotive Data Buses 20XX Telematics (MOST) ring network passenger compartment 22.5 MBit/s 2002 Telematics (MOST III) 150 MBit/s (2007 MOST 150) XX complex video processing systems for driver assistance Gbit/s x-by-wire engine management sensor networks for safety applications T > 85 C 2006 N.N., Hochschule Esslingen 68

69 Sensors for Vehicle Environment Investigation Quelle: Bosch Long-Range Radar Infrared Video Ultrasonic Video Long Distance Area Night Vision Medium Area Near Area Rear Area < 200 m < 150 m < 80m < 4m 2006 N.N., Hochschule Esslingen 69

70 Global Positioning System GPS Satellite in orbit 2006 N.N., Hochschule Esslingen 70

71 Final Technology for Autonomous Locomotion Autonomous driving a dream? The donkey brings you home! Drive and sleep? 2006 N.N., Hochschule Esslingen 71

72 Diploma Thesis Daniel Seibl University of Appl. Sciences in cooperation with Internship Uwe Strauß Bachelor Thesis Jan Lubkoll University of Appl. Sciences in cooperation with Thank you for your attention! Otto Strobel N.N., Hochschule Esslingen 72