11.光电器件培训教程.ppt

1、联系人：孙宇Welcome!,联系人：孙宇ShenZhen BEST OPTO.,深圳市佰思特光电技术有限公司,光电器件,撰写人：郑良桃 2005.3.22,联系人：孙宇Fabry-Perot Laser (FP) Distributed Feedback Laser (DFB) Light Emitting Diode (LED) Vertical Cavity Surface-Emitting Laser (VCSEL) Photo Diode (PD) Pin-Transimpedance (PIN-TIA)

2、Transceiver,Abstract,联系人：孙宇2. Fabry-Perot Laser (FP),Applications ATM SONET/SDH Fiber Channel,785 nm to 1550 nm. ATM and SONET/SDH applications operate at 1310 nm Moderate cost Edge-emitting device Operate in “closed loop” mode Moderate spectral width Threshold currents can range from 5

3、mA to 30mA at room temperature High speed (depending on design) can be used at data rates from 155 Mbps to 2.5 Gbps,联系人：孙宇Output current (bias plus modulation) must remain above the laser threshold current to avoid turn-on delay and optimize speed Can be used for distances to 40 km or l

4、onger Threshold current and slope efficiency vary significantly over temperature. Therefore, automatic power control (closed loop) is used to maintain a constant average power (using a monitor diode) and some form of temperature compensation is generally used for the modulation current Eye safety is

5、 not as big an issue with 1310 nm devices, but becomes important with short-wavelength devices (such as 785 nm),联系人：孙宇3. Distributed Feedback Laser (DFB),Applications ATM SONET/SDH Fiber Channel DWDM 10 Gbps,1310 or 1550 nm. WDM applications operate at separate wavelengths around 1550nm

6、 High cost Edge-emitting device Operate in “closed loop” mode, Sometimes with TE coolers Internal Bragg grating results in very narrow spectral width (SLM) Threshold currents can range from 5mA to 30mA at room temperature High speed (depending on design) can be used at data rates from 155 Mbps to 2.

7、5 Gbps,联系人：孙宇Used for longer distance (20km to 100km) / high data rate transmission Threshold current and slope efficiency vary significantly over temperature. Therefore, automatic power control (closed loop) is used to maintain a constant average power (using a monitor diode) and some

8、form of temperature compensation is generally used for the modulation current DWDM lasers require accurate temperature stabilization and therefore contain T/E cooler, thermistor, laser and wavelength locker.,联系人：孙宇4. Light Emitting Diode (LED),Applications FDDI 125 Mbps 100 Mbps Etherne

9、t ATM 155 Mbps 266 Mbps Fibre Channel Plastic Fiber,820 nm to 1320 nm, though most applications use 850 nm devices Very low cost Large beam divergence angle Operate in “open loop” mode Works across multiple data rates Low coupled output power (usually 20 to -14 dBm) High drive current (usually 60-10

10、0 mA),联系人：孙宇Lower speed (typically used at less than 300 Mbps) Higher capacitance Large spectral width Device speed, output power, and spectral width limit the applications to lower-speed (typically 300 Mbps) data rates at distances generally less than 2km,联系人：孙宇5. Vertical

11、 Cavity Surface Emitting Laser (VCSEL),Applications Parallel Arrays Gigabit Ethernet/10GbE Fiber Channel,Short wavelength (850 nm), although long wavelength are in development Low cost, High reliability,联系人：孙宇Surface emitting device (high yield can be optically tested before dicing) nar

12、row spectral width (can be SLM) Very low threshold current (10 Gbps Output current (bias plus modulation) must remain above the laser threshold current to avoid turn-on delay and optimize speed Some device exhibit a behavior called “off-state bounce” which can result in slower fall times VCSELs (Ver

13、tical Cavity Surface-Emitting Lasers) include geometries, circular output beams, high fiber optic coupling efficiencies, extremely low power consumption, and high modulation rates.,联系人：孙宇Threshold current varies much less on a VCSEL than an edge-emitting (FP or DFB) laser. However, auto

14、matic power control is still used to maintain a constant average power (using a monitor diode) and some form of temperature compensation is generally used for the modulation current. Eye safety is an issue with 850 nm wavelengths. Therefore, safety circuitry is required in the driver for most applic

15、ations in order to maintain eye safety - even with a single-point fault. Open loop operation is possible with some VCSELs, but maintaining eye safety is more difficult.,联系人：孙宇6. Laser Diode Characteristics,Power at 1/ Power at 0 = Extinction Ratio,Automatic Power Control to control aver

16、age power Temperature Compensation for modulation,Laser Characteristic,联系人：孙宇MM,FP,DFB,RMS,Center Wavelength,联系人：孙宇7. PhotoDiode (PD),PD Parameter,Sensitivity Sen VR=1V,1310nm 0.80 0.90 A/W,VR=1V,1550nm 0.85 0.90 A/W,Dark current ID VR=5V,T=250C 80 400 PA,Capacitance Cf F=1

17、MHz,VR=5V 0.60 0.80 PF,Return Loss RL 45 db,Band width BW -3dB, VR=5V 2.5 GHz,Wavelength 1100 1600 nm,OP Temperature -20 +70 0C,ST Temperature -40 +80 0C,Parameter Symbol Test condition Min. Type Max. Unit,联系人：孙宇Sensitivity,联系人：孙宇Dark current (ID),ID = V/ R V : Voltage ID :

18、 Dark current,联系人：孙宇Capacitance (Cf),Signal generation,OSC,10/（1/2fC）2+R21/2=U/R,K=1/2fC,R,联系人：孙宇Band width,isolator,coupler,optical power meter,photodiode,Laser,dBm=10lg(PO/1mW) dB=10lg(PO / PBIAS) RL=10lg(PO / PL ),Return Loss (RL),联系人：孙宇8. PIN-Transimpedance

19、 ( PIN-TIA),联系人：孙宇9. Transceiver,Post AMP,TIA,RD,LOS,APD or PIN photodiode,LD driver circuit,Laser diode,TD,Tx_Disable,Tx_Fault,SDA,SCL,Diagnostic Monitoring Interface,Memory,Extended ID,Function Block Diagram,联系人：孙宇联系人：孙宇Transmitter,Po (Output Power) L=(Po-Sen

20、)/K L: Transmission Instance Unit : km Sen: Sensitivity Unit : dBm Po: Output Power Unit : dBm K: Coefficient of Loss Unit : dBm/km SM: 1310nm K=0.4 MM: K=4 1550nm K=0.2,联系人：孙宇Extinction Ratio EX=10Log P1/P0 EX: Extinction Ratio Unit: dB P1 : is the output power when the signal is “1” U

21、nit: mW P0 : is the output power when the signal is “0” Unit: mW,联系人：孙宇联系人：孙宇Transmitter output eye,联系人：孙宇联系人：孙宇Receiver,Receiver Sensitivity Sensitivity expressed as a ratio of errored bits to correct bits (BER) BER is a function on signal to nois

22、e ratio (SNR) SONET required a BER of 10-10 GbE / FC require a BER of 10-12,联系人：孙宇Saturation Power To prevent errored bit on the output when no signal is present . If the power inputted into PhotoDiode is very big , the signal “1” is detected when the signal is “0” in fact .,1,0,0 or 1,联系人：孙宇Input Signal Detection To prevent chatter on the output when no signal is present. Threshold le