Dual-wavelength Fiber Lasers Based on Active Fibers with Structured Cores

Nanostructured or "pixelated" core fibers have attracted great attention thanks to possible design of optical fibers with almost arbitrary refractive index profile, including gradient index nanostructured core, large mode area fibers for high power applications or fiberized free-form optical components. A short review of applications of (nano)structured core active fibers in fiber lasers will be given followed by detailed study of the effect of heat treatment and fiber drawing on the luminescence properties important for fiber laser performance; and application of the erbium- and ytterbium structured-core active fibers in fiber lasers that operate simultaneously at 1 and 1.55 micrometer wavelengths.