Power transients in time-division multiplexed discrete Raman fibre amplifier

In this paper, the effect of addition and/or dropping of wavelength-division multiplexed channels in an all-optical gain-clamped time-division multiplexed (TDM) pumped discrete Raman fibre amplifier (DRFA) has been investigated experimentally and analyzed by numerical simulation. Nineteen signals were amplified in a counter-directionally pumped DRFA consisting of 13 km long dispersion compensating fibre. Light of eight DFB lasers was square-wave modulated at 2 kHz to imitate channel addition/dropping and combined with signals from five 10 Gigabit Ethernet transmitters and with six continuous wave signals. Power transients of the surviving channels caused by cross-gain modulation of the DRFA were monitored at the output of the amplifier. All-optical feedback loop was implemented in the form of a ring laser. Theoretical analysis of the TDM-pumped DRFA was based on numerical solution of coupled propagation equations for backward propagating pumps, signals, and both forward and backward propagating spectral components of amplified spontaneous emission powers. (c) 2009 Elsevier B.V. All rights reserved.