All-optical gain-controlled lumped Raman fibre amplifier

1. All-optical gain-controlled lumped Raman fibre amplifier Miroslav Karásek Jiří Kaňka Pavel Honzátko Jan Radil ONDM 04, Ghent, Belgium

2. All-optical gain-controlled lumped Raman fibre amplifierOutline • Transient effects in Raman fibre amplifiers • Numerical simulations • Experimental verification • Conclusions ONDM 04, Ghent, Belgium

3. All-optical gain-controlled lumped Raman fibre amplifierTransient effects in Raman fibreamplifiers • Optical amplifiers saturate on the total power basis • Channel addition/removal or transmission of packets in burst mode would result in output power fluctuations in other channels • Some measurements must be taken to eliminate unwanted output power fluctuations • Several schemes has been suggested for gain stabilization of EDFAs • For lumped Raman fibre amplifiers, the all-optical gain-clamping technique can be used ONDM 04, Ghent, Belgium

4. All-optical gain-controlled lumped Raman fibre amplifierNumerical simulations • Propagation of signals, pumps and spectral components of amplified spontaneous emission (ASE) is described by the following partial differential equation ONDM 04, Ghent, Belgium

5. All-optical gain-controlled lumped Raman fibre amplifierNumerical simulations • The above equation represents a set of partial differential equations for down-stream and up-stream propagating optical powers P+(z,t,ν), P-(z,t,ν) contained in frequency slot Δν and describe their evolution in space (along the fibre axis), z and time t • P+(z,t,ν), P-(z,t,ν) represent the down-stream signals P+s(z,t,νs), up-stream pumps P-p(z,t,νp) and down-stream and up-stream ASE spectral components PASE(z,t,ν) • Vg(ν), (ν) and γ(ν) is the frequency dependent group velocity, fiber background loss, and the Rayleigh back scattering coefficient • gR(ν-ζ) is the Raman gain coefficient between waves with frequency ν andζ, Keff and Aeff ONDM 04, Ghent, Belgium

6. All-optical gain-controlled lumped Raman fibre amplifierNumerical simulations Schematic diagram for numerical simulations. Boundary conditions for signals, pumps, and ASE components: ONDM 04, Ghent, Belgium

7. All-optical gain-controlled lumped Raman fibre amplifierNumerical simulations Simulation data: DCF - OFS EWBDK:1360 L=16km, D= -1260ps/nm Pp0(1445nm)=800mW 8 WDM channels starting at 1543nm 1nm spacing, Ps0 = -12dBm/channel Net gain at 1543nm as a function of input power ONDM 04, Ghent, Belgium

8. All-optical gain-controlled lumped Raman fibre amplifierNumerical simulations Output power variation at 1543nm Unclamped regime ONDM 04, Ghent, Belgium

9. All-optical gain-controlled lumped Raman fibre amplifierNumerical simulations Output power variation at 1543nm clamped regime ONDM 04, Ghent, Belgium

10. All-optical gain-controlled lumped Raman fibre amplifierNumerical simulations Time evolution of lasing power at 1551nm ONDM 04, Ghent, Belgium

11. All-optical gain-controlled lumped Raman fibre amplifierNumerical simulations Different degree of clamping ONDM 04, Ghent, Belgium

12. All-optical gain-controlled lumped Raman fibre amplifierExperiment Experimental set-up ONDM 04, Ghent, Belgium

13. All-optical gain-controlled lumped Raman fibre amplifierExperiment Spectral dependence of net gain ONDM 04, Ghent, Belgium

14. All-optical gain-controlled lumped Raman fibre amplifierExperiment Net gain at 1538nm as a function of input power ONDM 04, Ghent, Belgium

15. All-optical gain-controlled lumped Raman fibre amplifierExperiment Output power fluctuation at 1540nm with and without AOGC ONDM 04, Ghent, Belgium

16. All-optical gain-controlled lumped Raman fibre amplifierConclusions • Surviving channel power fluctuations in lumped RFA have been investigated both theoretically and experimentally • It has been shown, that when sufficient lasing is allowed, steady-state surviving channel power fluctuations may be completely eliminated • Remaining power surges are about 8 times lower than the steady-state power excursions without AOGC ONDM 04, Ghent, Belgium

17. All-optical gain-controlled lumped Raman fibre amplifier Thank you for your attention! ONDM 04, Ghent, Belgium