Characterization of Narrowband Generation Regime of a Random Fiber Raman Laser

We present a comprehensive overview of major properties of narrow generation regime in a fiber laser with randomly distributed feedback. Just above the generation threshold spectrum consists of ultra-narrow (measured width — 2 MHz, expected value — 1–100 kHz) localized modes, which evolve for time intervals of about 1 ms and decompose afterwards. We study the distribution of lifetimes and power of these modes and articulate the mechanism of modes’ decay as a nonlinear wave mixing process either with pump wave for low-dispersion fibers or with other spectral components within the generation spectrum otherwise.