I installed a simple system that consists of 10Gbps NRZ signal and cw pump laser mixed together across pump coupler co-propagating to a SMF. At the end of the fiber, the pump coupler counter-propagation is connected. The Raman pump laser is connected to this pump coupler counter-propagation. Raman pumping should enhance the conversion efficiency even with lower pump power, but I didn't see any effect of the Raman pump on the signal. The wavelengths were 1557, 1553, and 1455 nm for the signal, pump, and Raman pump respectively. I think the problem is in the pump coupler counter-propagation. Could anyone help me to solve this problem?