Efficient Raman fiber laser based on random Rayleigh distributed feedback with record high power

We report a high-power Raman fiber laser based on randomly extremely weak Rayleigh feedback. Based on a mirrorless configuration, a total output power of 73.7 W is achieved with an optical efficiency of 74.7%. The cavity length of the Raman fiber laser is only 300 m. The Stokes wave is centered at 1184 nm with 3 dB bandwidth of about 4 nm at the maximal power. The spectrum and time-domain behavior at the Raman Stokes wave generation threshold is different from previous random distributed feedback Raman fiber lasers. (letters)