光纤通信原理英文版chapter

1、1 1 1Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST2 2 2Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang,

2、 School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USSTThe Principle of photoelectric conversionThe Principle of photoelectric conversionThe Principle of photoelectric conversion1.1.1. External photoeffect:External ph

3、otoeffect:External photoeffect: Some metal material can Some metal material can Some metal material can emit electrons when it receive the photons.emit electrons when it receive the photons.emit electrons when it receive the photons.2. 2. 2. Photoconductive effect:Photoconductive effect:Photoconduct

4、ive effect: Photons Photons Photons can generate can generate can generate more free electrons in semiconductor so that the more free electrons in semiconductor so that the more free electrons in semiconductor so that the conductive property of material is changed.conductive property of material is

5、changed.conductive property of material is changed.3. 3. 3. Photovoltaic effect:Photovoltaic effect:Photovoltaic effect: Photons Photons Photons can separates the can separates the can separates the electrons and holes in P-N junction. The flow of electrons and holes in P-N junction. The flow of ele

6、ctrons and holes in P-N junction. The flow of these free charge carriers produces current.these free charge carriers produces current.these free charge carriers produces current.4. 4. 4. Thermo-effect of radiation:Thermo-effect of radiation:Thermo-effect of radiation: Photons heat special Photons he

7、at special Photons heat special material and produce current-material and produce current-material and produce current-pyroelectricity.pyroelectricity.pyroelectricity. 3 3 3Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineer

8、ingProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST The properties and parameters The properties and parameters The properties and parameters 1.1.1. I I IF() F() F() Photocurrent-luminous fluxPhotocurrent-luminous fluxPhotocurrent-luminous flux2.2.2. I I IF() F()

9、F() Photocurrent-wavelengthPhotocurrent-wavelengthPhotocurrent-wavelength3.3.3. I I IF F F（f f f） Photocurrent-frequencyPhotocurrent-frequencyPhotocurrent-frequency4.4.4. I I IF F F（）（）（）（）（）（） Photocurrent-voltagePhotocurrent-voltagePhotocurrent-voltage5.5.5. S=I /S=I /S=I / Integral sensitivity In

10、tegral sensitivity Integral sensitivity (for polychromatic light) (for polychromatic light) (for polychromatic light)6. 6. 6. S=I() /()S=I() /()S=I() /() Spectrum sensitivity Spectrum sensitivity Spectrum sensitivity (for monochromatic light) (for monochromatic light) (for monochromatic light)7. 7.

11、7. I I I=0 =0 =0 Dark current photocurrent-when =0Dark current photocurrent-when =0Dark current photocurrent-when =04 4 4Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Comp

12、uter Engineering , USST, USST, USST 1 Photomultiplier (PMT ) PMT is A detector or a vacuum tube which amplifies a signal more than 100 time. Principle: External photoeffect: Electrons released from a photocathode when exposed to light are through a series of dynodes (9 to 16 ), to get an acceleratio

13、n because of the strong electric field ; as each electron strikes a dynode stage, 2 to 5 secondary electrons are liberated and accelerated to the subsequent dynode; at last the anode will collect all electrons (overall gain of 106109) to form the current.5 5 5Prof. Yang, School of Optical-Electrical

14、 and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST6 6 6Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer En

15、gineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USSTHow to work?7 7 7Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engine

16、ering , USST, USST, USSTDriving Circuit8 8 8Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST 9 9 9Prof. Yang, School of Optical-Electr

17、ical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST101010Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Comput

18、er EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST(a)(a)(a) Sensitivity is biggest in the all detectors Sensitivity is biggest in the all detectors Sensitivity is biggest in the all detectors so that it is easy to do detection of weak so that it is eas

19、y to do detection of weak so that it is easy to do detection of weak signalsignalsignal . . . (b)(b)(b) Wavelength response and modulating Wavelength response and modulating Wavelength response and modulating frequency response are Okfrequency response are Okfrequency response are Ok. . .(c)(c)(c) I

20、t prevents from strong light emission. It prevents from strong light emission. It prevents from strong light emission.(d)(d)(d) It is expensive and easy to broken It is expensive and easy to broken It is expensive and easy to broken because it is made of glass tube.because it is made of glass tube.b

21、ecause it is made of glass tube.The characteristics of PMTThe characteristics of PMTThe characteristics of PMT111111Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer

22、Engineering , USST, USST, USST121212Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST 2 2 2 photoresistancephotoresistancephotoresistan

23、ce Principle: Principle: Principle: Photoconductive effectPhotoconductive effectPhotoconductive effect131313Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineer

24、ing , USST, USST, USSTIF(L) -Nonlinear141414Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST151515Prof. Yang, School of Optical-Electr

25、ical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST3 photovoltaic cell3 photovoltaic cell3 photovoltaic cell161616Prof. Yang, School of Optical-Electrical and Computer Engin

26、eeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USSTWhen RWhen RWhen RL L L0 0 0，U U U0 0 0， I I II I I S S S LinearLinearLinearWhen RWhen RWhen RL L L is increased , I is increased , I is increase

27、d , II I I Nonlinear Nonlinear Nonlinear171717Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USSTThe solar cell The solar cell The solar

28、cell for detectionfor detectionfor detection181818Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST Sojourner senses surface of Mars191

29、919Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST202020Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang,

30、School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST212121Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optic

31、al-Electrical and Computer Engineering , USST, USST, USST222222Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST4 Photodiode232323Prof.

32、 Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USSTConclusion: External photonsthat is, lightstrikes the semiconductor and separates the elect

33、rons and holes near the P-N junction. The flow of these free charge carriers produces current ,that is solar cell. External voltage (reverse bias) enhances this effect, that is the Photodiode.242424Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electri

34、cal and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST252525Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Compute

35、r Engineering , USST, USST, USST262626Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST272727Prof. Yang, School of Optical-Electrical a

36、nd Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USSTResponsivity of a photodiodeResponsivity of a photodiodeResponsivity of a photodiode Dark-current sensitivity Dark-current sensi

37、tivity Dark-current sensitivity282828Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USSTPIN Photodiode The major feature of this photodio

38、de is that it consists of a thick lightly doped intrinsic layer, sandwiched between thin p and n regions. A p-i-n photodiode is the most commonly employed light detector because of its ease in fabrication, high reliability, low noise, low voltage, and relatively high bandwidth, where up to 110 GHz h

39、as been achieved .292929Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USSTAvalanche Photodiodes (APDs)Relatively high (around 20 V) reve

40、rse voltage Relatively high (around 20 V) reverse voltage Relatively high (around 20 V) reverse voltage is applied. This voltage accelerates is applied. This voltage accelerates is applied. This voltage accelerates photogenerated electrons and holes, which photogenerated electrons and holes, which p

41、hotogenerated electrons and holes, which strike neutral atoms and separate other strike neutral atoms and separate other strike neutral atoms and separate other electrons and holes, causing avalanche electrons and holes, causing avalanche electrons and holes, causing avalanche process. process. proc

42、ess. APD internally amplifies APD internally amplifies APD internally amplifies photocurrent.photocurrent.photocurrent.303030Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and

43、Computer Engineering , USST, USST, USST313131Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USSTA array and quadrant detectors323232Prof.

44、 Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST5 Phototransistor333333Prof. Yang, School of Optical-Electrical and Computer EngineeringPro

45、f. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USSTThe picture of phototransistor343434Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer

46、 EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST6 MSM Photo-detectors The advantage of this photodetector, as compared with both types of photodiodes, is that a planar structure results in low capacitance and, consequently, in higher bandwidth. Indeed,

47、 the MSM photodetector promises to work at 300 GHz. Ease of fabrication is another advantage of a planar structure.A drawback to an MSM photodetector: its relatively low responsivity, which ranges from 0.4 to 0.7 A/W. MSM photodetectors are an area of intensive research and development today.353535P

48、rof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USSTThe structure of MSM photodetectorThis is not a p-n junction diode; however, its basic

49、This is not a p-n junction diode; however, its basic This is not a p-n junction diode; however, its basic mechanism of light-current conversion is still the mechanism of light-current conversion is still the mechanism of light-current conversion is still the same: Photons generate electron-hole pair

50、s whose same: Photons generate electron-hole pairs whose same: Photons generate electron-hole pairs whose flow makes current. flow makes current. flow makes current. 363636Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineeri

51、ngProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST A set of flat metal contacts is deposited on the surface of a semiconductor. These contacts are called fingers and they are biased alternately so that a relatively high electric field exists between the fingers. P

52、hotons strike the semiconductor material between the fingers and create electron-hole pairs, which are separated by the electric field; thus, electric current is created.373737Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engin

53、eeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST7 Pyroelectricity detectorPyroelectric effect: The certain materials of Pyroelectric effect: The certain materials of Pyroelectric effect: The certain materials of electric polarization, such as a tourmaline el

54、ectric polarization, such as a tourmaline electric polarization, such as a tourmaline crystal or a ceramic disk of barium titanate,crystal or a ceramic disk of barium titanate,crystal or a ceramic disk of barium titanate, can generate an electrical potential when they can generate an electrical pote

55、ntial when they can generate an electrical potential when they are heated or cooled because an increase in are heated or cooled because an increase in are heated or cooled because an increase in temperature prompts the spontaneous temperature prompts the spontaneous temperature prompts the spontaneo

56、us polarization Ppolarization Ppolarization PS S S to decrease as the dipole to decrease as the dipole to decrease as the dipole moments, on average, diminish in magnitude. moments, on average, diminish in magnitude. moments, on average, diminish in magnitude. A current flows to compensate for the c

57、hange A current flows to compensate for the change A current flows to compensate for the change in bound charge that accumulates on the in bound charge that accumulates on the in bound charge that accumulates on the crystal edges. crystal edges. crystal edges. 383838Prof. Yang, School of Optical-Ele

58、ctrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST393939Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Com

59、puter EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USSTUs=AedT/dt Us=AedT/dt Us=AedT/dt Is=Ae/Z dT/dtIs=Ae/Z dT/dtIs=Ae/Z dT/dt= Ae dT/dt= Ae dT/dt= Ae dT/dtThenThenThen， /Z/Z/ZCalling Pyroelectric Calling Pyroelectric Calling Pyroelectric coefficientcoe

60、fficientcoefficient404040Prof. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer EngineeringProf. Yang, School of Optical-Electrical and Computer Engineering , USST, USST, USST414141Prof. Yang, School of Optical-Electrical and Computer E