Raman threshold for nth-order cascade Raman amplification

We study theoretically and experimentally Raman threshold for 1, 2, … , n orders Stokes in a free running configuration. Using alternative way to solve the differential coupled equations that describe the stimulate Raman scattering, we find simple mathematical expressions that allow calculating the necessary pumping power to obtain Raman threshold for nth-order Stokes and the maximum output power available in each Stokes. The theoretical calculations coincide with the results obtained experimentally.

Research highlights
► Using a simple, new to the best of our knowledge, procedure we calculate Stokes up to the n-th order.
► The proposed equation system is capable of accurately predict power levels for the 1, 2, … nth Stokes peaks.
► In this work, theoretical and experimental Stokes peaks-determination are in good agreement.