Raman fiber laser with random distributed feedback based on a twin-core fiber.

An operation of a linearly polarized Raman fiber laser with random distributed feedback based on a polarization-maintaining twin-core fiber (TCF) is demonstrated for the first time, to the best of our knowledge. The results indicate that the TCF allows one to obtain laser generation with a linewidth that is about five times smaller than that for the random laser based on a conventional fiber with similar parameters. The reasons for narrowing include both the weakening of nonlinear effects due to the power density reduction and the spectrally selective properties of the TCF.