Pushing the limits of 2micron-emitting silicate fiber lasers using nanoparticle doping

Thulium-doped fibers have gained considerable interest as “eye-safer” laser systems. However, efficient gain at 2-m requires high Tm-doping to facilitate cross-relaxation, which leads to fiber compositions and designs that push manufacturing limits. Proposed here is a 3-year basic research effort into novel compact high power, eye-safe laser sources based on (Tm) nanoparticles doped into intrinsically low nonlinearity optical fibers. This program will explore Tm-doped NP fibers with enhanced cross-relaxation using the unique ability of NPs to isolate gain ions in very high local concentrations, ideal for 2-m laser systems. In addition to understanding the underlying materials science and optical / laser physics, slope efficiencies of > 60% will be the target while leveraging the highly localized doping associated with NPs to alleviate the current requirements of complex fiber designs. Furthermore, while NP doping affords high local (nm-scale) gain ion concentrations, the overall doping of the NPs into the entire core can be relatively low, which significantly reduces the thermal load of the laser. This work brings together novel materials science, (optical) fiber engineering, and laser and optical physics to develop novel nano-scale heterogeneous power-scalable fiber amplifiers and lasers.