Photonic crystal fibers (PCFs) have been extensively studied over the past decade. They are formed of a core surrounded by an artificially-engineered photonic crystal cladding with nano scale features. Light can be guided in a low-index hollow (air or gas) core with a photonic band gap cladding, as well as in a solid glass core more like a conventional fiber. In fibers with hollow cores the deleterious nonlinear effects are significantly reduced, damage threshold increased, the dispersion can be controlled, and optical attenuation is very low. In addition, they can be used to make all-fiber gas cells, or to deliver particles or atoms down a fiber using optical forces. Solid core fibers are formed by using the photonic crystal cladding as an effective-index medium with a refractive index between that of glass and that of air. With careful design it is possible to obtain radical nonlinear-optical responses, leading to a range of laser-based broadband light sources, or to obtain very large single mode cores and high-numerical aperture inner claddings, which are essential for high power fiber lasers.

This talk will focus on exploiting PCFs for achieving high power fiber lasers and wavelength converters. Specifically, a high peak power fiber laser design along with experimental results will be presented. Furthermore, an efficient scheme for intra-cavity coherent addition of two PCF laser channels will be presented along with experimental results demonstrating more than 95% combining efficiency. Finally, our recent investigations on wavelength conversion to the mid-IR via degenerate four-wave-mixing in silica PCFs, will be presented.