1. © 2005, it - instituto de telecomunicações. Todos os direitos reservados. This tutorial is licensed under the Creative Commons http://creativecommons.org/licenses/by-nc-sa/3.0/ Fiber Amplifiers- Raman Sérgio Stevan, Paulo André, António Teixeira, J. Prat, J. A. Lazaro, C. Bock, João Andrade

2. 2 E1- 2b Optical technologies Jan 2006 Outline Introduction Physical principle Propagation. Power and Field Configurations and SETUPs Co, Counter and Bi - directional Distributed and lumped Noise and Multi Path Interference Raman fiber Lasers

3. 3 E1- 2b Optical technologies Jan 2006 Introduction - History 1970 –Stimulated Raman emission in optical fibers was observed by Ippen, and by Stolen et al. in 1971 [3] 70 and 80 decades – Development of new types of fiber Middle 90 decade – 1991 (first commercial EDFA amplified link) = attentions shifted until 1997 (FBG and Development of suitable high power pumps) 1999 - The first Demonstration of Raman amplification.

4. 4 E1- 2b Optical technologies Jan 2006 Raman Optical Amplifiers  Based on fiber Non-Linear effects (larger pump power required) http://www.research.att.com/viewProject.cfm?prjID=111

5. 5 E1- 2b Optical technologies Jan 2006 Introduction Raman: Advantages and Disadvantages Occurs in all fiber transparency Maximum gain is shifted 13 THz from pump frequency Uses the same medium of the signal transmission Small Noise (compared with EDFA and SOA) Gain spectrum adjustable with multiple pumps (width and flatness) Gain is distributed along the fiber span Raman Gain occurs only at high pump powers Low efficiency in typical fibers

6. 6 E1- 2b Optical technologies Jan 2006 Stokes and Anti-Stokes Effects

7. 7 E1- 2b Optical technologies Jan 2006 Stimulated Raman Scattering (SRS) Islam M.N., "Raman Amplifiers for Telecommunication 1", 2004 (R.H. Stolen,“Fundamentals of Raman Amplification in Fibers”)

8. 8 E1- 2b Optical technologies Jan 2006 Normalized Raman Gain (SMF) Islam M.N., "Raman Amplifiers for Telecommunication 1", 2004 (R.H. Stolen,“Fundamentals of Raman Amplification in Fibers”)

9. 9 E1- 2b Optical technologies Jan 2006 Raman Gain X type of optic fiber Clifford Headley, Govind P. Agrawal, “Raman Amplification in fiber optical communication systems,” Elsevier academic press, 2005

10. 10 E1- 2b Optical technologies Jan 2006 Signal and Pump : Polarization M.N. Islam “Raman amplifiers for telecommunications”,IEEE Journal of Selected Topics in Quantum Electronics, 8, 548-559 (2002)

11. 11 E1- 2b Optical technologies Jan 2006 Lumped or Distributed Raman Amplifier Lumped: Distributed:

12. 12 E1- 2b Optical technologies Jan 2006 Distributed Raman Amplifier (DRA) M.N. Islam “Raman amplifiers for telecommunications”, IEEE Journal of Selected Topics in Quantum Electronics, 8, 548-559 (2002).

13. 13 E1- 2b Optical technologies Jan 2006 A Simple Raman Amplifier

14. 14 E1- 2b Optical technologies Jan 2006 Equations – Raman Amplification - Simplified Differential Equations - Pump Propagation (undepleted approach) - Signal Propagation

15. 15 E1- 2b Optical technologies Jan 2006 Power Signal x pump direction CO-PROPAGATING COUNTER-PROPAGATING F. Cisternino, B. Sordo, ''State of the art and prospects for Raman amplification in long distance optical transmissions'', Exp, Vol. 2 n. 1, pp. 18-25, March 2002.

16. 16 E1- 2b Optical technologies Jan 2006 Co-, Counter- and Bi-pumping 100% = Signal and Pump CO-PROPAGATING 0 % = Signal and Pump COUNTER-PROPAGATING Intermediate values = Bidirectional pumps J. Bromage, P.J. Winzer, and R.-J. Essiambre, in Raman Amplifiers for Telecommunications, M.N. Islam, Ed., Springer, New York, 2003, Chap.15

17. 17 E1- 2b Optical technologies Jan 2006 Pumping Methods FORWARDBACKWARD BI DIRECTIONAL Clifford Headley, Govind P. Agrawal, “Raman Amplification in fiber optical communication systems,” Elsevier academic press, 2005

18. 18 E1- 2b Optical technologies Jan 2006 Power variation Equations

19. 19 E1- 2b Optical technologies Jan 2006 Field Equation : Nonlinearities

20. 20 E1- 2b Optical technologies Jan 2006 Nonlinearities Penalties

21. 21 E1- 2b Optical technologies Jan 2006 Multi pump – gain Spectrum tayloring J.Bromage, J.Lightwave Technol.22,79 (2004)

22. 22 E1- 2b Optical technologies Jan 2006 Multi pump - Flat gain S. Namiki and Y.Emori, IEEE J.Sel.Topics Quantum Electron,7,3 (2001)

23. 23 E1- 2b Optical technologies Jan 2006 Gain (Flat) and Noise – 45km SMF (example) 1416nm 1502nm Used by permission from VPIphotonics, a division of VPIsystems

24. 24 E1- 2b Optical technologies Jan 2006 Gain (Flat) and Noise figure – 45km SMF Bandwidth = 90nm Used by permission from VPIphotonics, a division of VPIsystems

25. 25 E1- 2b Optical technologies Jan 2006 ASE and Noise Figure F. Cisternino, B. Sordo, ''State of the art and prospects for Raman amplification in long distance optical transmissions'', Exp, Vol. 2 n. 1, pp. 18-25, March 2002.

26. 26 E1- 2b Optical technologies Jan 2006 Gain and Noise Figure for many pump powers Islam M.N., "Raman Amplifiers for Telecommunication 1", 2004 (C.R.S Fludger,”Linear Noise Characteristics”)

27. 27 E1- 2b Optical technologies Jan 2006 MPI – Multi Path Interference Clifford Headley, Govind P. Agrawal, Raman Amplification in fiber optical communication systems, Elsevier academic press, 2005

28. 28 E1- 2b Optical technologies Jan 2006 MPI – Multi Path Interference

29. 29 E1- 2b Optical technologies Jan 2006 Raman Fiber Laser Resonant Cavity FBG reflectors Multi-lasers There is no coupler insertion loss Setup simpler than traditional approach which consists of multiplexing laser diodes Consequently: Smaller costs

30. 30 E1- 2b Optical technologies Jan 2006 Spectral positions of pump, gratings and gain distribution S bandC bandL band

31. 31 E1- 2b Optical technologies Jan 2006 Setup of comb Raman fiber lasers with two pumps Pump1FBG for Pump1Pump 2FBG for Pump2 1430 nm1520 nm1460 nm1548 nm 1529 nm 1554 nm 1535 nm 1569 nm 1570 nm Ppump1 = 1.5 W Ppump2 = 1.5 W 30km SMF

32. 32 E1- 2b Optical technologies Jan 2006 Raman Gain composition

33. 33 E1- 2b Optical technologies Jan 2006 Sixth-Order Cascaded Raman Amplification S.B. Papernyi and V.B. Ivanov

34. 34 E1- 2b Optical technologies Jan 2006 Rayleigh Backscatering (Virtual mirror): Raman Fiber Laser

35. 35 E1- 2b Optical technologies Jan 2006 Rayleigh Scattering and fiber lasing a) Multiple chaotic oscillations b) FBG inserted to Pump power = 0.8W c) FBG inserted to Pump power = 1.2W Teixeira A., Stevan Jr., S. Silveira T.; Nogueira R.; Tosi Beleffi G. M., Forin D., Curti F., “Optical Gain Characteristics of Rayleigh Backscattered Lasing in Several Fibre Types”, NOC 2005-07-07

36. 36 E1- 2b Optical technologies Jan 2006 Hybrid Amplification with Raman EDFA: population inversion Raman: bandwidth control Islam M.N., Raman Amplifiers for Telecommunications 2:, Sub- Systems and Systems, Springer, 2004 (Cap.13 Hybrid EDFA/ Raman Amplifiers, Hiroji Masuda)

37. 37 E1- 2b Optical technologies Jan 2006 Hybrid Amplification with Raman 22 dBm 11dBm 22 dBm Islam M.N., Raman Amplifiers for Telecommunications 2:, Sub- Systems and Systems, Springer, 2004 (Cap.13 Hybrid EDFA/ Raman Amplifiers, Hiroji Masuda)

38. 38 E1- 2b Optical technologies Jan 2006 Hybrid Amplification with Raman Hybrid EDFA/Raman Bandwidth can be tailored ~80nm Lower NF than EDFA separate Islam M.N., Raman Amplifiers for Telecommunications 2:, Sub- Systems and Systems, Springer, 2004 (Cap.13 Hybrid EDFA/ Raman Amplifiers, Hiroji Masuda)

39. 39 E1- 2b Optical technologies Jan 2006 Tellurite-based Raman Amplifier Islam M.N., Raman Amplifiers for Telecommunications 2:, Sub- Systems and Systems, Springer, 2004 (Cap.13 Hybrid EDFA/ Raman Amplifiers, Hiroji Masuda)