Raman fibre amplifier with time-division-multiplexed pumping

Year: 2005

Miroslav Karásek, DSc.; Jiří Kaňka, Ph.D.; Pavel Honzátko, Ph.D.; Pavel Peterka, Ph.D. 

Application of stimulated Raman scattering for signal amplification in dense wavelength division multiplexing communication systems is gaining on importance. In conventional wide-band multi-wavelength continuously pumped Raman fibre amplifier (RFA), spectral dependence of optical signal-to-noise ratio is deteriorated by pump-to-pump interactions.

We have theoretically studied and experimentally verified RFA with time division multiplexed (TDM) pumping in which several fixed wavelength laser diodes are optically combined together as in the continuous wave (CW) pumping scheme but individual lasers are operated in pulsed regime at separate times slots. This technique guarantees that at a given spot of the Raman fibre and at a particular time instant, pump wave of only one wavelength is present so that pump-to-pump Raman interactions are avoided. We have developed a large-signal numerical model of TDM pumped RFA. Performance of the model was demonstrated by simulation of wide-band four-wavelength-pumped discrete RFA. Optical properties of the TDM pumped RFA were compared with an equivalent CW pumped RFA and improved flatness of the OSNR was demonstrated [1, 2]. Results of theoretical and experimental investigation on RFA gain stabilization are summarized in [3, 4].

1. M. Karásek, J. Kaňka, J. Radil, J, Vojtěch, „Large signal model of TDM-pumped Raman fiber amplifier“, IEEE Phot. Technol. Lett., vol. 17, pp.1848-1850, 2005
2. M. Karásek, J. Kaňka, G.R. Khan, J. Radil, “Design of all-optical gain-clamped lumped Raman fibre amplifier for optimal dynamic performance”, IEE Proc. Optoelectronics, vol. 152, pp.223-229, 2005
3. M. Karásek, J. Kaňka, P. Honzátko, and P. Peterka, „Modelling of a pump-power-controlled gain-locking system for multi-pump wideband Raman fibre amplifiers“, IEE Proceedings Optoelectronics, vol. 151, No. 2, pp. 74-80, 2004.
4. M. Karásek, J. Kaňka, J. Radil, „Analysis of channel addition/removal response in all-optical gain-clamped cascade of lumped Raman fiber amplifier, J. Lightwave Technol., vol. 22, No. 10, pp.2271-2278, 2004