Linearly-polarized high-power Raman fiber lasers near 1670 nm

We developed linearly-polarized and diffraction-limited Raman fiber laser (RFL) sources in the 1650–1680 nm spectral range with up to 6.2 W of output power. The pump laser near 1550 nm is a MOPA consisting of a laser diode seed source and two amplifier stages based on different erbium-doped fibers. Two RFL configurations using a PM single-mode fiber as Raman gain fiber are demonstrated and laser performances are numerically simulated. The first is a free-running laser configuration achieving 6.25 W of output power at 1655 nm and a conversion efficiency of 79%. In the second scheme, an all-fibered RFL using fiber Bragg gratings and emitting 5 W of output power at 1679 nm is demonstrated. In the latter case, performances limitations due to spectral broadening are analyzed.