A new light at the end of the tunnel: fiber gas discharge lasers

Optical fibers have emerged as a transformative platform for building better and more robust solid state lasers. However, the wavelengths available to these lasers are limited. Using hollow core optical fibers allows us to add gases as new potential gain media for fiber lasers, and also liberates the gas laser from the limits normally imposed by diffraction. To demonstrate the new technology, we present a fiber laser at 3500 nm wavelength, using an antiresonant guiding hollow core optical fiber containing neutral xenon atoms pumped by an afterglow discharge of a helium-xenon mixture within a fiber of over 1 m in length. Laser action is confirmed through observation of polarization dependence, mode pulling and mode beating. Our results unlock a new breed of flexible fiber lasers operating at a plethora of wavelengths, many previous unavailable.