raman amplifier

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Raman AmplifierRaman Amplifier

IntroductionBasic Raman ConceptHigh Power Raman Fiber Lasers Raman Fiber AmplifierCombining EDFA and Raman AmplifierConclusion

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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

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Basic Raman ConceptBasic Raman Concept

Raman scattering from molecular vibrationBrillouin scattering from sound wave: Brillouin Amplifier

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Basic Raman ConceptBasic Raman Concept

Spontaneous process: linearStimulated process: Raman laserCoherent anti-Stokes scattering: Raman amplifier

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Basic Raman Concept Basic Raman Concept

Raman Spectrum from SiO2 fiber

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Basic Raman Concept Basic Raman Concept

Need high power laserNeed large Raman cross sectionGeO2 Germania: Large Raman cross-section, refractive index

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Raman Fiber Laser Raman Fiber Laser

Higher-order Raman spectrumLaser source: Raman fiber laser

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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

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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

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Raman Fiber Laser Raman Fiber Laser

How Does Cascaded Raman Laser Work

Raman Stokes Stimulated Raman Scattering Four Wave MixingEasy phase matching

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Raman AmplifierRaman Amplifier

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Raman AmplifierRaman Amplifier

Coherent anti-Stokes Scattering

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Raman AmplifierRaman Amplifier

Phase Matching

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Raman AmplifierRaman Amplifier

Amplifier Gain

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Raman AmplifierRaman Amplifier

Wide bandwidth Raman amplifier can be realized using multiple pumps

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Raman AmplifierRaman Amplifier

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Raman Amplifier Raman Amplifier

Lossless transmission by Raman amplifier

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Raman Amplifier Raman Amplifier

Walk-off due to wavelength mismatch in a pulsed Raman amplifier

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Raman Amplifier Raman Amplifier

Multistage AmplifierCounter propagating pump

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EDFA+Raman EDFA+Raman

Combined Raman and EDFA transmission Experiment: DWDM (Lucent)

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EDFA+Raman EDFA+Raman

Wide band amplification is possible by dividing into sub-bands (Lucent)

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EDFA+Raman EDFA+Raman

Gain-flattened EDFA+Raman ( Japan)

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EDFA+Raman EDFA+Raman

Gain-flattened EDFA+Raman ( Japan)

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EDFA+Raman EDFA+Raman

Gain-flattened EDFA+Raman (Japan)

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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

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ReferencesReferences

Optical Fiber Telecommunications, Ivan P. Kaminow (1997)Optical Amplifier and Their Application, Douglas M. Baney(1998)Waveguide Optoelectronics, J. H. March (1990)