Ch3 06 Optical Amplifiers,Regenerators.ppt
Optical Communications: Circuits, Systems and DevicesChapter 3: Optical DevicesAmplifiers, Regeneratorslecturer: Dr. Ali Fotowat AhmadySep 2012Sharif University of Technology1
Chapter 3 Optical DevicesAmplifiers, RegeneratorsOptical Amplifiers vs Regenerators (1 of 2) Transparent: Regenerators specific to bit rate and modulation formatused; O-Amps are insensitive Easily upgraded: A system with optical amplifiers can be more easilyupgraded to higher bit rate without replacing the amplifiers Optical amplifiers have large gain bandwidths key enabler of DWDM Issues:- Amplifiers introduce additional noise that accumulates- Spectral shape of gain (flatness), output power, transient behaviorneed to be carefully designedSep 2012Sharif University of Technology2
Chapter 3 Optical DevicesAmplifiers, RegeneratorsOptical Amplifiers vs Regenerators (2 of 2)Sep 2012Sharif University of Technology3
Chapter 3 Optical DevicesAmplifiers, RegeneratorsOEO RegeneratorThe model of a generator and the three major functions, optical receiver,electronic amplifier, and optical transmitterSep 2012Sharif University of Technology4
Chapter 3 Optical DevicesAmplifiers, Regenerators1R, 2R and 3R RegenerationSep 2012Sharif University of Technology5
Chapter 3 Optical DevicesAmplifiers, RegeneratorsOptical Amplifier Varieties (1 of 2) Semiconductor Optical Amplifiers (SOA)- conventional SOA- GC-SOA (Gain-Clamped SOA)- LOA (Linear Optical Amplifier) Fiber Optical amplifiers (FOA)- Rare earth-Doped Fiber Amplifiers Erbium-Doped Fiber Amplifiers (EDFA) : C,L-Band Thulium-Doped Fiber Amplifiers (TDFA) : S-Band Praseodymium-Doped Fiber Amplifiers (PDFA):OBand- Not based on stimulated emission but on nonlinear effectsSep 2012Sharif University of Technology6
Chapter 3 Optical DevicesAmplifiers, RegeneratorsOptical Amplifier Varieties (2 of 2)- Fiber Raman Amplifiers Discrete Raman Amplifiers Distributed Raman Amplifiers (DRA)- Hybrid EDFA/Raman AmplifierSep 2012Sharif University of Technology7
Chapter 3 Optical DevicesAmplifiers, RegeneratorsOptical Amplification: mechanicsFor sustained amplification, the rate of excitation should be equal to therate of stimulation the rate of spontaneous emissionSep 2012Sharif University of Technology8
Chapter 3 Optical DevicesAmplifiers, RegeneratorsErbium-Doped Fiber Amplifier (EDFA) Length of fiber: core doped with (rare earth) erbium ions Er3 Fiber is pumped with a laser at 980 nm or 1480nm. Pump is coupled (in- and out-) using a λ-selective coupler An isolator is placed at the end to avoid reflections (else this may willconvert into a laser!)An EDFA amplifier consists of an erbium-doped silica fiber, an optical pump, a couplerand isolators at both endsSep 2012Sharif University of Technology9
Chapter 3 Optical DevicesAmplifiers, RegeneratorsEDFA success factors Availability of compact and reliable high-power semiconductor pump lasers EDFA is an all-fiber device polarization-independent & easy to couplelight in/out Simplicity of device No crosstalk introduced while amplifying!Sep 2012Sharif University of Technology10
Chapter 3 Optical DevicesAmplifiers, RegeneratorsEDFA Operation (1 of 2) When Er3 ions introduced in silica, electrons disperse into an energyband around the lines E1, E2, E3 (Stark splitting) Within each band, the ion distribution is non-uniform (thermalization) Due to these effects, a large λ range (50 nm) can be simultaneouslyamplified & luckily it is in the 1530nm range 980 nm or 1480nm pumps are used to create a population inversionbetween E2 and E1 980 nm pump E1 E3 (absorption) & E3 E2 (spontaneousemission) 1480 nm pump E1 E2 (absorption, less efficient) Lifetime in E3 is 1µs, whereas in E2 it is 10msSep 2012Sharif University of Technology11
Chapter 3 Optical DevicesAmplifiers, RegeneratorsEDFA Operation (2 of 2)Energy Level States of Erbium: While the energy states are represented as horizontal lines,they are really “energy bands” centered around a specific energy state. This distribution ofenergy is called a “Fermi-Dirac Distribution”.Sep 2012Sharif University of Technology12
Chapter 3 Optical DevicesAmplifiers, RegeneratorsSemiconductor Optical Amplifiers (SOA) SOAs have severe crosstalk problems, besides others but used in switchesetc Semiconductor optical amplifiers are devices based on conventional laserprinciples.Sep 2012Sharif University of Technology13
Chapter 3 Optical DevicesAmplifiers, RegeneratorsRaman Amplifiers Power transferred from lower-λ to higher-λ channels (about 100nm) Eg: 1460-1480nm pump amplification at 1550-1600nm Gain can be provided at ANY wavelength (all you need is an appropriatepump λ!) Multiple pumps can be used Lumped or distributed designs possible Used today to complement EDFAs in ultra-long-haul systemsSep 2012Sharif University of Technology14
Chapter 3 Optical DevicesAmplifiers, RegeneratorsPrinciples of Raman amplificationSep 2012Sharif University of Technology15
Chapter 3 Optical DevicesAmplifiers, RegeneratorsQualitative comparison between Raman and OFAs (1 of 2)Sep 2012Sharif University of Technology16
Chapter 3 Optical DevicesAmplifiers, RegeneratorsQualitative comparison between Raman and OFAs (2 of 2)ParameterEDFARAMANSOAGain 30 dB 20–25 dB 10–20 dBOutput PowerHighHighLowInput PowerModerateHighHighCross TalkLowLowVery highApplicationMetro, long haulLong haul,ultra long haulShort haul,single channelSep 2012Sharif University of Technology17
Chapter 3 Optical DevicesAmplifiers, RegeneratorsLong-Haul All-optical AmplificationAll optical amplification (EDFA Raman) and dispersion compensation modules (DCM)enable the optical signal to reach ultra long distances ( 4,000 km) between end terminals.Sep 2012Sharif University of Technology18
Chapter 3 Optical DevicesAmplifiers, RegeneratorsQuestionsSep 2012Sharif University of Technology19
Optical Amplifiers vs Regenerators (1 of 2) Transparent: Regenerators specific to bit rate and modulation format used; O-Amps are insensitive Easily upgraded: A system with optical amplifiers can be more easily upgraded to higher bit rate without replacing the amplifiers Optical amplifiers
M O CH3 R2 L R1 H H L O M O CH3 H L R1 R2 H L O M O H H L R1 R2 H3C L R1 OML2 CH3 O M O H R 2 L R1 H H3C L R1 OML CH3 R12 O CH3 OH R1R2 O CH3 OH R12 O CH3 OH R1R2 O CH3 OH FAVORED DISFAVORED FAVORED DISFAVORED Reviews: Zimmerman and Traxler proposed that the aldol
4 Naming Alkanes General Formula: CnH(2n 2) suffix: -ane Parent Names: 1 CH4 Methane CH4 2 CH3CH3 Ethane C2H6 3 CH3CH2CH3 Propane C3H8 4 CH3(CH2)2CH3 Butane C4H10 5 CH3(CH2)3CH3 Pentane C5H12 6 CH3(CH2)4CH3 Hexane C6H14 7 CH3(CH2)5CH3 Heptane C7H16 8 CH3(CH2)6CH3 Octane C8H18 9 CH3(CH2)7CH3 Nonane C9H20 10 CH3(CH2)8CH3 Decane C10
Water Soluble by-product is easily removed in aqueous work-up Urea formed is partially soluble in many solvents and hard to purify via column chromatography Urea formed is soluble in most organics. This is advantageous in solid phase synthesis. NCN CH3 CICH3C NCN CH3 H3C CH3 CH3 BMC NCN H3C CH3 CH3 CH3 BEC NCN N,N-dicyclopentylcarbodiimide NCN .
asymmetric dihydroxylation 73% H3C O NHFmoc H3C O OH O H3C CH3 O HN O O CCl3 CH3 OH Cl OCH3 O HN N O H CH3 Cl H3C O OCH3 H3C O O O H3C CH3 O HN O O CCl3 CH3 O Cl H3C O OCH3 H3C O O CH3 CH3 NHFmoc O HN O O CCl3 3 OH R O The Shi epoxidation system provided the desired epoxide in a 6:1 diastereomeric ratio, while other epoxidation methods never .
4EXPERIMENTALPROCEDURES 87 MaterialsandMethods 87 Photolyses 88 TpW(NHPh)(CC(CH3)3)Cl(3) 88 TpW(NHPh-p-Br)(CC(CH3)3)a(4) 89 TpW(NHPh-3,5(CF3)2)(CC(CH3)3)Cl(5) 89 TpW(NH2)(CC(CH3)3)Cl(6) 90 TpW(NHPh)2(CC(CH3)3)(7) 90 Tp’W(NHPh)(CC(CH3)
RF/IF Differential Amplifiers 5 Low Noise Amplifiers 7 Low Phase Noise Amplifiers 10 Gain Blocks 11 Driver Amplifiers 13 Wideband Distributed Amplifiers 13 Power Amplifiers 15 GaN Power Amplifiers 18 Variable Gain Amplifiers 19 Analog Controlled VGAs 19 Digitally Controlled VGAs 20 Baseband Programmable VGA Filters 21 Attenuators 22
Optical Amplifiers All-opticalcomponents (i.e. optical input/output). Fibre-based amplifiers also contain lasers, but this is to create a population inversion in the gain medium. Have replaced electronics-based regenerators, in which optical signals had to be photodetected, amplified electronic
ADVANCED BOOKKEEPING KAPLAN PUBLISHING Introduction When a capital asset or non-current asset is disposed of there are a variety of accounting calculations and entries that need to be made. Firstly, the asset being disposed of must be removed from the accounting records as it is no longer controlled. In most cases the asset will be disposed of for either more or less than its carrying value .
