光线通信 第1讲-Introduction.ppt

1、,http:/ txxy. qqhru. ,College of Communication and Electronic Engineering,授课教师： 陶佰睿 办公地点： 11教507 联系电话：E_ mail ： Tongxin_,光纤通信,Optical Fiber Communications,齐齐哈尔大学通信与电子工程学院 通信071-074,2,教学参考书 Reference,互联网资源Internet,.tw/GKEISER http: /bbs. tong-xin. com,名校精品课程 Excel

2、lent Course,武汉理工大学 电子科技大学 哈尔滨工业大学,齐齐哈尔大学通信与电子工程学院 通信071-074,3,knowledge target,Ability target,齐齐哈尔大学通信与电子工程学院 通信071-074,4,Example Platform(JH5002）,PCM Encoding,CMI Encoding,Scrambling / descrambling Verilog -HDL,Multiplexing/ demultiplexing,齐齐哈尔大学通信与电子工程学院 通信071-074,5,OptiSystem,OptiSystem是Optiwave

3、光通讯系统模拟软件，整个通讯系统的讯号处理。 视窗化的使用介面及丰富的元件库为其特色。 CATV or TDM/WDM网络设计 SONET/SDH环形网络设计 发射器、通道、放大器、接收器设计 使用不同的接收器估计误码率及系统的损失 放大系统误码率及link budget计算 色散分析,齐齐哈尔大学通信与电子工程学院 通信071-074,6,齐齐哈尔大学通信与电子工程学院 通信071-074,7,Fiber-optic communication,It is a method of transmitting information from one place to another by se

4、nding light through an optical fiber. The light forms an electromagnetic carrier wave that is modulated to carry information.,1. Introduction,齐齐哈尔大学通信与电子工程学院 通信071-074,8,Fiber-optic communication,The process of communicating using fiber-optics involves the following basic steps: Creating the optical

5、 signal using a transmitter, relaying the signal along the fiber, ensuring that the signal does not become too distorted or weak, and receiving the optical signal and converting it into an electrical signal.,齐齐哈尔大学通信与电子工程学院 通信071-074,9,1.1 Electromagnetic Spectrum,750 nm,380 nm,齐齐哈尔大学通信与电子工程学院 通信071

6、-074,10,1880 Alexander Graham Bell 1930 Patents on tubing 1950 Patent for two-layer glass wave-guide 1960 Laser first used as light source 1965 High loss of light discovered 1970s Refining of manufacturing process （光纤通信元年，1970年美国康宁公司首先制造20dB/km的光纤） 1980s OF technology becomes backbone of long distan

7、ce telephone networks in NA.,1.2 Evolution of Fiber,1966年英籍华人科学家高锟与Hockham提出用玻璃可以制成衰减 为20dB/km的通信光导纤维。（2009年诺贝尔物理学奖，Fiber, CCD ）,齐齐哈尔大学通信与电子工程学院 通信071-074,11,Development Milestones,齐齐哈尔大学通信与电子工程学院 通信071-074,12,四大里程碑 1960年，世界上第一台相干振荡光源红宝石激光器问世。 1970年，美国康宁玻璃公司的卡普隆（Kapron）博士等 拉制出损耗仅为20 dB/km的光纤 1985年，南

8、安普敦大学的Mears等人制成了掺铒光纤放大器（erbium-doped fiber amplifier, EDFA） 90年代，光纤光栅、全光纤光子器件、平面波导器件及其集成的出现,齐齐哈尔大学通信与电子工程学院 通信071-074,13,This tiny electronically tiltable mirror is a building block in devices such as all-optical cross-connects and new types of computer data projectors.,I/O Fibers,Imaging Lenses,Ref

9、lector,MEMS 2-axis Tilt Mirrors,Micro Electro Mechanical Switches,齐齐哈尔大学通信与电子工程学院 通信071-074,14,1.3 Major elements of an optical fiber link,齐齐哈尔大学通信与电子工程学院 通信071-074,15,OPTICAL FIBER,An optical fiber (or fibre) is a glass or plastic fiber that carries light along its length. Light is kept in the core

10、 of the optical fiber by total internal reflection.,齐齐哈尔大学通信与电子工程学院 通信071-074,16,Advantages of Optical Fibre,Thinner Less Expensive Higher Carrying Capacity Less Signal Degradation& Digital Signals Light Signals Non-Flammable Light Weight,齐齐哈尔大学通信与电子工程学院 通信071-074,17,Advantages of fiber optics,Much

11、Higher Bandwidth (G bps) - Thousands of channels can be multiplexed together over one strand of fiber Immunity to Noise - Immune to electromagnetic interference (EMI). Safety - Doesnt transmit electrical signals, making it safe in environments like a gas pipeline. High Security - Impossible to “tap

12、into.”,齐齐哈尔大学通信与电子工程学院 通信071-074,18,Advantages of fiber optics,Less Loss - Repeaters can be spaced 75 miles apart (fibers can be made to have only 0.2 dB/km of attenuation) Reliability - More resilient than copper in extreme environmental conditions. Size - Lighter and more compact than copper. Flex

13、ibility - Unlike impure, brittle glass, fiber is physically very flexible.,齐齐哈尔大学通信与电子工程学院 通信071-074,19,Fiber Optic Advantages,greater capacity (bandwidth up to 2 G bps, or more) smaller size and lighter weight lower attenuation immunity to environmental interference highly secure due to tap difficu

14、lty and lack of signal radiation,19,齐齐哈尔大学通信与电子工程学院 通信071-074,20,DisAdvantages of fiber optics,Disadvantages include the cost of interfacing equipment necessary to convert electrical signals to optical signals. (optical transmitters, receivers) Splicing fiber optic cable is also more difficult.,齐齐哈尔

15、大学通信与电子工程学院 通信071-074,21,Fiber Optic Disadvantages,expensive over short distance requires highly skilled installers adding additional nodes is difficult,21,齐齐哈尔大学通信与电子工程学院 通信071-074,22,Three Windows,齐齐哈尔大学通信与电子工程学院 通信071-074,23,Telecommunications Local Area Networks Cable TV CCTV Optical Fiber Senso

16、rs,1.4 Areas of Application,齐齐哈尔大学通信与电子工程学院 通信071-074,24,Fiber Optic Cable,relatively new transmission medium used by telephone companies in place of long-distance trunk lines also used by private companies in implementing local data networks require a light source with injection laser diode (ILD) o

17、r light-emitting diodes (LED) fiber to the desktop in the future,24,齐齐哈尔大学通信与电子工程学院 通信071-074,25,Fiber Optic Cable,齐齐哈尔大学通信与电子工程学院 通信071-074,26,Optical fiber consists of a core, cladding, and a protective outer coating, which guides light along the core by total internal reflection.,Core thin glass

18、center of the fiber where light travels. Cladding outer optical material surrounding the core Buffer Coating plastic coating that protects the fiber.,1.5 Structure of Fiber,齐齐哈尔大学通信与电子工程学院 通信071-074,27,Preform Preparation Chemical Vapor Deposition(O2 and SiCl4) SMF (dopant: GeCl4) Change composition

19、 to vary refractive index Fiber Drawing Heating (around 1600C) Drawing (d monitor TC & V m/s) Coating (Polymer) Volume Conserves,Fiber Fabrication,齐齐哈尔大学通信与电子工程学院 通信071-074,28,齐齐哈尔大学通信与电子工程学院 通信071-074,29,OPTICAL FIBER,The core, and the lower-refractive-index cladding, are typically made of high-qua

20、lity silica glass, though they can both be made of plastic as well.,齐齐哈尔大学通信与电子工程学院 通信071-074,30,Fiber Optic Layers,consists of three concentric sections,30,齐齐哈尔大学通信与电子工程学院 通信071-074,31,Fiber Optic Cable,31,齐齐哈尔大学通信与电子工程学院 通信071-074,32,Fiber Undersea Attenuation,Attenuation Source (water contaminati

21、on) Hydrogen Vibration (1.08um to 1.24um & 1.59um) OH formation (1.3um to 1.50um) 1 Water Contamination OH Water leaks into optical fiber, creating OH- H gets trapped in fiber defect centers, creating Si-OH Solutions Prevent water contamination provide better isolation Prevent introduction of hydrog

22、en use less active metal Prevent diffusion of hydrogen Silicon Oxynitride coating Prevent absorption due to OH Shift the resonance frequency away from the 1.3um to 1.5um range (Pre-treat with deuterium or fluorine),1. Polyethylene 2. Mylar tape 3. Stranded metal (steel) wires 4. Aluminum water barri

23、er 5. Polycarbonate 6. Copper or aluminum tube 7. Petroleum jelly 8. Optical fibers 2,齐齐哈尔大学通信与电子工程学院 通信071-074,33,Photons (light “particles”) light represented by tiny bundles of energy (or quanta), following straight line paths along the rays.,1.6 Physics of Light,齐齐哈尔大学通信与电子工程学院 通信071-074,34,PHYS

24、ICS OF LIGHT,PLANCKS LAW Ep =hf Where, Ep energy of the photon (joules) h = Plancks constant = 6.625 x 10 -34 Js f frequency o f light (photon) emitted (hertz),齐齐哈尔大学通信与电子工程学院 通信071-074,35,INDEX OF REFRACTION,齐齐哈尔大学通信与电子工程学院 通信071-074,36,Total Internal Reflection,齐齐哈尔大学通信与电子工程学院 通信071-074,37,Snells

25、Law,齐齐哈尔大学通信与电子工程学院 通信071-074,38,Snells Law,齐齐哈尔大学通信与电子工程学院 通信071-074,39,Snells Law,齐齐哈尔大学通信与电子工程学院 通信071-074,40,Total Internal Reflection in Fiber,齐齐哈尔大学通信与电子工程学院 通信071-074,41,Two main categories of optical fiber used in fiber optic communications are multi-mode optical fiber and single-mode optica

26、l fiber.,1.7 Mode of Propagation,齐齐哈尔大学通信与电子工程学院 通信071-074,42,Types of Fibers:,step-indexmultimode,nc,nc,nf,nc,nc,nf,nc,nc,step-indexsinglemode,GRIN,Multi-mode step index,Single-mode step index,multi-mode graded index,齐齐哈尔大学通信与电子工程学院 通信071-074,43,Advantages: Only one mode is allowed due to diffracti

27、on/interference effects. Allows the use high power laser source Facilitates fusion splicing similar fibres Low dispersion, therefore high bandwidth (a few GHz). Low loss (0.1 dB/km),Disadvantages: Costly,dn = 0.005, 5ps/km,Step-index Single-mode Fibre,齐齐哈尔大学通信与电子工程学院 通信071-074,44,Advantages: Allows

28、the use of non-coherent optical light source, e.g. LEDs Facilitates connecting together similar fibres Imposes lower tolerance requirements on fibre connectors. Cost effective,Disadvantages: Suffer from dispersion (i.e. low bandwidth (a few MHz) High power loss,Input pulse,n2 = 1.46,dn=0.04,100 ns/k

29、m,Step-index Multi-mode Fibre,齐齐哈尔大学通信与电子工程学院 通信071-074,45,Advantages: Allows the use of non-coherent optical light source, e.g. LEDs Facilitates connecting together similar fibres Imposes lower tolerance requirements on fibre connectors. Reduced dispersion compared with STMMF,Disadvantages: Lower b

30、andwidth compared with STSMF High power loss compared with the STSMF,dn = 0.04,1ns/km,Graded-index Multi-mode Fibre,齐齐哈尔大学通信与电子工程学院 通信071-074,46,Fiber Optic Types,multimode step-index fiber the reflective walls of the fiber move the light pulses to the receiver multimode graded-index fiber acts to refract the light toward the center of the fiber by variations in the density single mode fiber the light is