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January 8, 2008 Y. Lin: Raman Amplifier 1
Raman AmplifierRaman Amplifier
IntroductionBasic Raman ConceptHigh Power Raman Fiber Lasers Raman Fiber AmplifierCombining EDFA and Raman AmplifierConclusion
January 8, 2008 Y. Lin: Raman Amplifier 2
IntroductionIntroduction
Raman Amplifier was demonstrated in the 1980s Unavailability of high-power diode laser pump sourceWhy do you need it : amplify signals from 1270 to 1670 nmany optical fiber can serve as the amplifying mediumRaman process itself provides high-power laserDisadvantage: Cross-talk
January 8, 2008 Y. Lin: Raman Amplifier 3
Basic Raman ConceptBasic Raman Concept
Raman scattering from molecular vibrationBrillouin scattering from sound wave: Brillouin Amplifier
January 8, 2008 Y. Lin: Raman Amplifier 4
Basic Raman ConceptBasic Raman Concept
Spontaneous process: linearStimulated process: Raman laserCoherent anti-Stokes scattering: Raman amplifier
January 8, 2008 Y. Lin: Raman Amplifier 5
Basic Raman Concept Basic Raman Concept
Raman Spectrum from SiO2 fiber
January 8, 2008 Y. Lin: Raman Amplifier 6
Basic Raman Concept Basic Raman Concept
Need high power laserNeed large Raman cross sectionGeO2 Germania: Large Raman cross-section, refractive index
January 8, 2008 Y. Lin: Raman Amplifier 7
Raman Fiber Laser Raman Fiber Laser
Higher-order Raman spectrumLaser source: Raman fiber laser
January 8, 2008 Y. Lin: Raman Amplifier 8
Raman Fiber Laser Raman Fiber Laser
High power are possible5 W, 9.2 W diode-pumped Nd3+ cladding-pumped Raman fiber lasers 6.8 W diode-pumped Yb3+ cladding-pumped Raman fiber lasers
January 8, 2008 Y. Lin: Raman Amplifier 9
Raman Fiber Laser Raman Fiber Laser
High-order Raman scatteringPartially reflecting (20%) fiber gratingEight out of ten photons are converted to the output Capable of generating high power light at any wavelength from 1.2 to 1.7 microns
January 8, 2008 Y. Lin: Raman Amplifier 10
Raman Fiber Laser Raman Fiber Laser
How Does Cascaded Raman Laser Work
Raman Stokes Stimulated Raman Scattering Four Wave MixingEasy phase matching
January 8, 2008 Y. Lin: Raman Amplifier 11
Raman AmplifierRaman Amplifier
January 8, 2008 Y. Lin: Raman Amplifier 12
Raman AmplifierRaman Amplifier
Coherent anti-Stokes Scattering
January 8, 2008 Y. Lin: Raman Amplifier 13
Raman AmplifierRaman Amplifier
Phase Matching
January 8, 2008 Y. Lin: Raman Amplifier 14
Raman AmplifierRaman Amplifier
Amplifier Gain
January 8, 2008 Y. Lin: Raman Amplifier 15
Raman AmplifierRaman Amplifier
Wide bandwidth Raman amplifier can be realized using multiple pumps
January 8, 2008 Y. Lin: Raman Amplifier 16
Raman AmplifierRaman Amplifier
January 8, 2008 Y. Lin: Raman Amplifier 17
Raman Amplifier Raman Amplifier
Lossless transmission by Raman amplifier
January 8, 2008 Y. Lin: Raman Amplifier 18
Raman Amplifier Raman Amplifier
Walk-off due to wavelength mismatch in a pulsed Raman amplifier
January 8, 2008 Y. Lin: Raman Amplifier 19
Raman Amplifier Raman Amplifier
Multistage AmplifierCounter propagating pump
January 8, 2008 Y. Lin: Raman Amplifier 20
EDFA+Raman EDFA+Raman
Combined Raman and EDFA transmission Experiment: DWDM (Lucent)
January 8, 2008 Y. Lin: Raman Amplifier 21
EDFA+Raman EDFA+Raman
Wide band amplification is possible by dividing into sub-bands (Lucent)
January 8, 2008 Y. Lin: Raman Amplifier 22
EDFA+Raman EDFA+Raman
Gain-flattened EDFA+Raman ( Japan)
January 8, 2008 Y. Lin: Raman Amplifier 23
EDFA+Raman EDFA+Raman
Gain-flattened EDFA+Raman ( Japan)
January 8, 2008 Y. Lin: Raman Amplifier 24
EDFA+Raman EDFA+Raman
Gain-flattened EDFA+Raman (Japan)
January 8, 2008 Y. Lin: Raman Amplifier 25
Conclusions Conclusions
High-power laser sources are available by Raman process itself.200 to 400 nm Bandwidth Amplifiers are possibleRaman, EDFA combinationFlat gain for WDMNew fiber lasers and gratings make it practicalSystem with Terabits of capacity are possible
January 8, 2008 Y. Lin: Raman Amplifier 26
ReferencesReferences
Optical Fiber Telecommunications, Ivan P. Kaminow (1997)Optical Amplifier and Their Application, Douglas M. Baney(1998)Waveguide Optoelectronics, J. H. March (1990)