Gain Properties of multi-wavelength time division multiplexed Raman amplifier

We report gain properties of the multi-wavelength pulsed Raman pump. Based on fiber dispersion property, we obtain the group velocity difference between pump pulses which imposes the upper limit of pulse repetition rate beyond which pump-to-pump interaction occurs. The pump-to-pump interaction can be severe when pump instantaneous power is high due to small duty cycle. However, bigger duty cycle imposes much lower limit to the pulse repetition rate. Therefore, an optimized level of duty cycle is required. In addition, shorter pump wavelength separation helps to increase the upper limit of pulse repetition rate. Ultimately this will improve the noise performance of TDM Raman amplifier.