RIN transfer suppression technique for dual-order Raman pumping schemes

An optical technique is demonstrated for suppressing the relative intensity noise (RIN) transfer from a high-power second-order pump laser to the signal radiation in a copropagating dual-order Raman pumping scheme. RIN transfer suppression is accomplished by intensity-modulating a low-power semiconductor laser diode first-order pump. Measurements are presented demonstrating suppression over the entire electronic bandwidth and -20-dB suppression spanning a 23-nm optical bandwidth. This technique may facilitate the use of high-power fiber lasers in copropagating dual-order distributed Raman amplifiers.