Highly efficient Raman fiber laser Collaborators: E. Blanger M. Bernier B. Dry D. Faucher Ral Valle OUTLINE I: Raman scattering and gain II: Raman fiber lasers (two generations) III: Standard Model IV: Experimental set-up V: Results & discussion VI: Conclusion I: Raman fiber laser (RFL) Raman scattering Spontaneous Stimulated D.J. Dougherty, et al. Opt. Lett. 20, (1995) Raman gain = 1m Pump Stokes Evolution of the Stokes and pump signals : Forward SRS 2. Time-dispersion tuning: C. Lin et al. Appl. Phys. Lett. 31 (1977) CW 1. Angular tuning: Raman fiber lasers: 1 st generation R. Stolen et al. Appl. Phys. Lett. 30, (1977) 340 Raman fiber lasers: 2 nd generation Key elements were developed for the 2 nd generation of RFL Fiber Bragg gratings providing reduced losses, spectral selectivity & tunability Low loss fibers standard or with high Ge or P content High power Ytterbium fiber lasers providing power, reliability and spectral bandwidth Raman fiber lasers: 2 nd generation Nested cavities Spectral coverage E.M. Dianov et al., Quantum Electron. 35, (2005) PpPp PsfPsf PsbPsb P p IN P s OUT 0 L Z P p IN P s OUT R1R1 R2R2 1108nm 1165nm Bragg gratings Standard numerical model Boundary conditions: Standard numerical model Propagation equations: R IC = 99% Laser optimisation vs R OC Laser optimisation vs L R IC = 99% R OC = 26% II: Highly efficient FRL (15 W) Corning HI980 (9% Ge) Experimental set-up Pump Stokes Parameters used in simulationOC1 configurationOC2 configuration Fiber attenuation p dB/km Fiber attenuation s dB/km Splicing losses0.03 dB IC gray losses0.04 dB IC cladding-mode s eff OC gray losses0.01 dB OC cladding-mode s 0.00 dB IC reflectivity99.6 % OC reflectivityR eff /55 %R eff /26 % Spectral broadening First configuration: OC1 Laser curve with OC1 Stokes vs absorbed pump with OC1 Second configuration: OC2 IC OC2 Laser curve with OC2 Stokes vs absorbed pump with OC2 Effective reflectivity Effective reflectivity (OC2) Cladding-mode losses (IC) Effective losses (IC/OC2) Laser curve with OC2 Tuning of FBGs : Set-up Tuning curve Conclusion RFL with efficiencies approaching quantum limit can be obtained using well designed FBGs. The standard model (AuYeung & Yariv) can be used provided effective R and are considered. 10 W output is achievable from an optical fiber with a moderate Ge content. Tunability over tens of nm is expected.