Pump energy source, method of providing pump energy to an optical transmission system, and optical transmission system

摘要

It is disclosed a pump energy source (20) for providing pump energy (E_p) to an optical transmission system (100) transmitting an optical signal along an optical fiber, in particular an optical transmission system (100) in which a beam of said pump energy (E_p) is introduced to said optical fiber so that said beam of said pump energy (E_p) copropagates with said optical signal.;Said pump energy (E_p) is used for distributed Raman amplification of said optical signal, preferably in a forward pumping configuration. To provide said pump energy (E_p) with a low relative intensity noise (RIN), said pump energy source (20) is equipped with an auxiliary optical fiber (1) that is capable of imparting Raman amplification to an optical signal travelling in said auxiliary optical fiber (1), an auxiliary source (2) providing an auxiliary source signal (E_s) that can be introduced to said auxiliary optical fiber (1), and with an auxiliary pump (3) providing an auxiliary pump signal (E_p_aux) that can be introduced to said auxiliary optical fiber (1) so that it counterpropagates with said auxiliary source signal (E_s), whereby said auxiliary source signal (E_s) is amplified by Raman amplification in a backward pumping configuration thus contributing to a low RIN (Figure 1).