Fiber Gas Raman lasers

Gas stimulated scattering has been demonstrated to be an effective method to obtain tunable, narrow linewidth light sources of otherwise unobtainable wavelengths, especially in the ultra-violet and infrared spectral range. In traditional gas cells the effective interaction length is very short and the system can be bulky and cumbersome, limiting the applications of these lasers. The advent of anti-resonance hollow core fibers and their properties of long effective interaction length, high optical confinement, and the possibility of control of the effective gain spectrum make it possible to develop a novel type of laser, fiber gas Raman lasers, which combines the advantages of both fiber and gas lasers. By properly designing the transmission bands of hollow-core fibers, selecting active gases and pump sources, fiber gas Raman lasers can potentially provide a wide range of emission wavelengths from the UV to the IR. Owing to the nature of transitions in atomic and molecular gases, fiber gas Raman lasers are spectrally narrow even without additional linewidth limiting measures. We have demonstrated nanosecond, hundred kilowatt peak-power, gigahertz linewidth, 1.5μm and 2μm fiber gas Raman lasers using the anti-resonance hollow-core fibers made by Bath University in UK. Our work provides a very possible way to obtain mid-infrared fiber lasers by gas stimulated Raman scattering in hollow-core fiber designed specially pumped with normal fiber lasers.