第三章光纖通信器件

1、用戶網(wǎng)傳輸網(wǎng)交換網(wǎng)接入網(wǎng)光 有 源 器 件光 無 源 器 件關(guān)鍵技術(shù)：SDH ATMTDMWDMTDMWDM支撐基礎(chǔ)：定義：定義：需要外加能源驅(qū)動(dòng)工作的光電子器件需要外加能源驅(qū)動(dòng)工作的光電子器件半導(dǎo)體光源半導(dǎo)體光源(LD,LED,DFB,QW,SQW,VCSEL)(LD,LED,DFB,QW,SQW,VCSEL)半導(dǎo)體光探測器半導(dǎo)體光探測器(PD,PIN,APD(PD,PIN,APD）光纖激光器（光纖激光器（OFL:OFL:單波長、多波長）單波長、多波長）光放大器光放大器(SOA,EDFA)(SOA,EDFA)光波長轉(zhuǎn)換器光波長轉(zhuǎn)換器(XGM,XPM,FWM)(XGM,XPM,FWM)光調(diào)制器

2、（光調(diào)制器（EAEA）光開關(guān)光開關(guān)/ /路由器路由器定義：定義：不需要外加能源驅(qū)動(dòng)工作的光電子器件不需要外加能源驅(qū)動(dòng)工作的光電子器件光纖連接器（固定、活動(dòng)光纖連接器（固定、活動(dòng),FC/PC,FC/APC,FC/PC,FC/APC）光纖定向耦合器光纖定向耦合器/ /分支器分支器光分插復(fù)用器（光分插復(fù)用器（OADM)OADM)光波分光波分/ /密集波分復(fù)用器（密集波分復(fù)用器（WDM/DWDM)WDM/DWDM)光衰減器（固定、連續(xù)）光衰減器（固定、連續(xù)）光濾波器（帶通、帶阻）光濾波器（帶通、帶阻）光纖隔離器與環(huán)行器（偏振有關(guān)、無關(guān)）光纖隔離器與環(huán)行器（偏振有關(guān)、無關(guān)）光偏振態(tài)控制器、光纖延遲線、光

3、纖光柵光偏振態(tài)控制器、光纖延遲線、光纖光柵電線 光纖 調(diào)制器 光調(diào)制器 電阻 光衰減器 三通（多通） 光耦合器 二極管 光隔離器 混頻器 光波分復(fù)用器 放大器 光放大器 頻率轉(zhuǎn)換器 光波長轉(zhuǎn)換器 濾波器 光濾波器 電載波 光載波 電接插件 光連接器 探頭 光探測器 開關(guān) 光開關(guān) 集成電路 集成光路 多波長光源多波長光源DWDM光調(diào)制器光調(diào)制器光隔離器光隔離器光耦合器光耦合器光波長轉(zhuǎn)換光波長轉(zhuǎn)換光放大光放大DWDM光色散補(bǔ)償光色散補(bǔ)償光隔離器光隔離器光環(huán)行器光環(huán)行器光波長轉(zhuǎn)換光波長轉(zhuǎn)換OADMDWDM光隔離器光隔離器光環(huán)行器光環(huán)行器光開關(guān)光開關(guān)可調(diào)諧濾波可調(diào)諧濾波DWDMOXC光耦合器光耦合器光

4、調(diào)制解調(diào)光調(diào)制解調(diào) 光電變換器件 光開關(guān)與調(diào)制器件 光放大器件 光色散補(bǔ)償器件 光網(wǎng)絡(luò)器件 F-P腔激光二極管(LD) 分布反饋布拉格激光器(DFB) 分布布拉格反射激光器(DBR) 外腔激光器與Q開關(guān)激光器 發(fā)光二極管(LED) 光纖激光器(OFL) 垂直腔表面發(fā)射激光器(VCSEL) 多波長光源與波長可調(diào)諧激光器多波長光源與波長可調(diào)諧激光器 光電探測器(PD、PIN、APD) 幅度調(diào)制 機(jī)械調(diào)制 電光調(diào)制 直接調(diào)制 電吸收光調(diào)制(EA) 相位調(diào)制 偏振調(diào)制 光電集成芯片(OEIC) 光子集成芯片(PIC) 摻鉺光纖放大(EDFA) 摻鐠光纖放大(PDFA) 摻釹光纖放大(NDFA) 分布式

5、光纖放大 喇曼光纖放大(SRFA) 布里淵光纖放大(SBFA) 半導(dǎo)體光放大(SOA) 色散控制 色散位移單模光纖 非零色散位移單模光纖 大有效截面單模光纖 色散平坦單模光纖 色散補(bǔ)償 色散補(bǔ)償光纖模塊 SOA色散補(bǔ)償 光纖光柵色散補(bǔ)償 色散管理色散補(bǔ)償說明： Different wavelengths travel at slightly different speeds(this effect is called “Chromatic Dispersion”) Chromatic dispersion causes pulse broadening(problem at high bit

6、rates over long distances) Standard single-mode fiber: 1300 nm window has lowest CD1550 nm lowest loss 光耦合透鏡（自聚焦透鏡、玻璃球透鏡） 光連接器與光耦合器 光隔離器與光環(huán)行器 光濾波與光波分復(fù)用器件 光起偏器與偏振控制器 光波長轉(zhuǎn)換與光波長路由器件 光調(diào)制解調(diào)器（Optical Modem） 光衰減器與光延時(shí)器件 光開關(guān)與光交叉連接器件 微光電機(jī)械芯片光器件技術(shù)光器件技術(shù) 光纖技術(shù) 微光學(xué)（Microoptics) technology 平面波導(dǎo)（Planar waveguide）技術(shù)

7、微光電機(jī)械(Micro-Optic-Electronic-Mechanic）技術(shù) Fibre is not only a transmission medium. （光纖不僅僅是傳輸媒體） Many devices such as amplifiers and filters can be made from fibre. （許多器件是由光纖制成，如光纖放大器、濾波器等） Components usually end up connected to a fibre for transmission. （器件與光纖相連便于傳輸） 器件由傳統(tǒng)的光學(xué)元件，如透鏡、棱鏡、衍射光柵等，裝配而成 尺寸小，

8、精度高 裝配難度高，機(jī)械程度低 較昂貴 采用半導(dǎo)體芯片制造技術(shù)，由硅或其它半導(dǎo)體材料在平板上所形成的器件（Devices are constructed on the surface of a flat piece of material such as silica or semiconductor crystal using the techniques of semiconductor chip manufacturing)光源和光接收器/Light-emitting Diode (LED) 原理：半導(dǎo)體PN結(jié)發(fā)光（自發(fā)輻射光） 光譜：寬帶光譜 應(yīng)用：短距離、小容量數(shù)據(jù)通信（通過空間/多

9、模光纖傳輸） Key characteristics Most common for 780, 850, 1300 nm Total power up to a few W Spectral width 30 to 100 nm Coherence length 0.01 to 0.1 mm Little or not polarized Large NA ( poor coupling into fiber)P -3 dBP peakBW光源和光接收器/ FP( Fabry-Perot ) Laser 原理：半導(dǎo)體PN結(jié)發(fā)光 平行平面反射腔 激光 光譜：多縱模光譜 （Multiple lon

10、gitudinal mode ，MLM) 應(yīng)用： “Classic” semiconductor laserFirst fiberoptic links (850 or 1300 nm)Today: short & medium range linksP peakIPThreshold光源和光接收器/ FP( Fabry-Perot ) Laser Key characteristics Most common for 850 or 1310 nm Total power up to a few mw Spectral width 3 to 20 nm Mode spacing 0.7

11、 to 2 nm Highly polarized Coherence length 1 to 100 mm Small NA ( good coupling into fiber)光源和光接收器/ FP( Fabry-Perot ) LaseryxzSOP: linearhorizontalSOP: linearvertical偏振（Polarization）說明： Most lasers are highly polarized Degree of polarization (DOP):DOP = P polarized / P total State of polarization (S

12、OP):describes the orientationand rotation of thepolarized light光源和光接收器/分布反饋 (DFB) Laser 原理：半導(dǎo)體PN結(jié)發(fā)光 分布反饋反射腔 激光 光譜：單縱模光譜 (Single longitudinal mode， SLM) 應(yīng)用： High performance telecommunication laser Most expensive (difficult to manufacture)Long-haul links & DWDM systemsP peakSMSR光源和光接收器/分布反饋 (DFB)

13、 Laser Key characteristics Mostly around 1310/1550 nm Total power 3 to 50 mw Spectral width 10 to 100 MHz (0.08 to 0.8 pm) Sidemode suppression ratio (SMSR): 50 dB Coherence length 1 to 100 m Small NA ( good coupling into fiber)光源和光接收器/ 垂直腔面發(fā)光激光器 Vertical Cavity Surface Emitting Lasers (VCSEL) Distr

14、ibuted Bragg Reflector (DBR) Mirrors Alternating layers of semiconductor material 40 to 60 layers, each l / 4 thick Beam matches optical acceptance needs of fibers more closely Key properties Wavelength range 780 to 980 nm (gigabit ethernet) Spectral width: -10 dBm Coherence length:10 cm to10 m Nume

15、rical aperture: 0.2 to 0.3activen-DBRp-DBROther Light Sources White light source Specialized tungsten light bulb Wavelength range 900 to 1700 nm, Power density 0.1 to 0.4 nw/nm (SM), 10 to 25 nw/nm (MM) Amplified spontaneous emission (ASE) source “Noise” of an optical amplifier without input signal

16、Wavelength range 1525 to 1570 nm Power density 10 to 100 w/nm External cavity laser Most common for 1550 nm band (some for 1310 nm) Tunable over more than 100 nm, power up to 10 mw Spectrum similar to DFB laser, bandwidth 10 kHz to 1 MHzPhotodiodes(光電管） PIN (p-layer, intrinsic layer, n-layer) Highly

17、 linear, low dark current Avalanche photo diode (APD) Gain up to x100 lifts detected optical signal above electrical noise of receiver Best for high speed and highly sensitive receivers Strong temperature dependence Main characteristics Quantum efficiency (electrons/photon) Dark current Responsivity

18、 (current vs. L L)n+Bias VoltageAPD GainMaterial Aspects Silicon (Si) Least expensive Germanium (Ge) “Classic” detector Indium gallium arsenide (InGaAs) Highest speedWavelength nm50010001500SiliconGermaniumInGaAsQuantum Efficiency = 10.10.51.0Responsivity (A/W) 類型 *T型耦合器 *星型耦合器 *定向耦合器 * 波分復(fù)用/解復(fù)用器 結(jié)構(gòu)

19、 *光纖型 *微光學(xué)器件型 主要技術(shù)指標(biāo) *耦合比(CR) * 插入損耗(IL) * 附加損耗(EL) *方向性（DL) * 隔離度（Is) *一致性（U) 常用耦合器類型 IL(Insertion Loss) IL=-10lg Reflect the power to each port. CR(Coupling Ratio) CR= EL(Excess Loss) EL=-10lg The total loss on coupler PoutPinPout1Pout1+Pout2Pout1+Pout2Pin DL DL = 10Log(Pj / Pi) 方向性對(duì)傳輸系統(tǒng)的影響 *同路異向雙

20、信道對(duì)傳系統(tǒng) M X N器件i1jM1N發(fā)射1接收2發(fā)射2接收1 *同路同向雙信道傳輸系統(tǒng) * 樹形網(wǎng)傳輸系統(tǒng) 發(fā)射1發(fā)射2接收2接收1發(fā)射1XN * 光纖耦合器 光纖定向耦合 星型 光纖分波/合波 原理單模光纖傳播 Equations：dR/dz- jdR = -jKS; dS/dz+ jdS = -jKR A=R exp(-jdz); An= S exp(jdz) Detuning coefficient：d=(bn-b)/2 Coupling coefficient: K 方程解 )sin()sin()cos(2222222222zKKjKSzKKjzKRdddddd-= 波分復(fù)用/解復(fù)

21、用原理 微器件型耦合器 波導(dǎo)型耦合器 An isolator is a device that allows light to pass along a fibre in one direction but not in the opposite direction.Isolators/應(yīng)用 Main application: To protect lasers and optical amplifiers from light coming back (which otherwise can cause instabilities) Insertion loss: Low loss (0.2

22、 to 2 dB) in forward direction High loss in reverse direction:20 to 40 dB single stage, 40 to 80 dB dual stage) Return loss: More than 60 dB without connectorsIsolators/工作原理 隔離器工作原理 Light entering at any particular port (say port 1) travels around the circulator and exits at the next port (say port

23、2). Light entering at port 2 leaves at port 3 and so on.Circulators/應(yīng)用Circulator & chirped FGB configured to compensate CD Optical crystal technology similar to isolators Insertion loss 0.3 to 1.5 dB, isolation 20 to 40 dBTypical configuration: 3 port device Port 1 -Port 2 Port 2 -Port 3 Port 3

24、-Port 1Fast l lSlow l l環(huán)形器應(yīng)用：Add / Drop NodesFilter reflects l l iAdd l l iAdd / DropDielectric thin-film filter designCirculator with FBG designCommonPassbandDrop l l iFilter Characteristicsl l i-1l l il l i+1PassbandCrosstalkCrosstalk Passband Insertion loss Ripple Wavelengths(peak, center, edges)

25、 Bandwidths (0.5 dB, 3 dB, .) Polarization dependence Stopband Crosstalk rejection Bandwidths (20 dB, 40 dB, .)Dielectric Filters Thin-film cavities Alternating dielectric thin-film layers with different refractive index Multiple reflections cause constructive & destructive interference Variety of filter shapes and bandwidths (0.1 to 10 nm) Insertion loss 0.2 to 2 dB, stopband rejection 30 to 50 dBLayersSubstrateIncoming SpectrumReflected SpectrumTransmitted Spectrum1535 nm1555 nm0 dB30 dBTunable Fabry-Perot Filters Filter shape Re