A powerful and widely tunable double-pass fiber Raman laser

Abstract

We demonstrate a powerful double-pass fiber Raman laser widely tunable in the visible and near-IR, realized by high power pumping of a large-core low-loss multimode optical fiber in a simple double-pass fiber laser arrangement with Littrow-prism-tuned emission. Using a 200-μm-core-diameter 40-m-long multimode fiber as an active Raman gain medium pumped with more than 400 kW pulse power, coupled into the fiber from the second harmonic of a Q-switched Nd:YAG laser ( λ p = 532 nm), we obtain laser emission combining simultaneously a broadband tunable spectral range in the visible and near-IR (540–970 nm) and a high output power (larger than 12 kW corresponding to an energy larger than 0.1 mJ) which represents the maximum output power achieved by a tunable fiber Raman laser.