Phosphate glass nanostructured core fiber for laser with dual wavelength emission

In recent years the novel active glass materials for optical fibers with broadband emission are of great interest due to potential application in spectroscopy, environmental monitoring or medicine. Development of that kind materials is based on elaborating the glass matrix co-doped with different rare earth ions, e.g. Er, Yb, Ho, Tm. Glasses doped with multiple rare earths characterize with a high number of spectroscopic parameters, due to the presence of energy transfer phenomena between those different rare earth ions. Nonlinear nature of that phenomena varying with the dopants concentration levels, makes the design and development of optical fibers made of glass doped with several active ions not trivial. In this work, we present the nanostructured material composed of several separated glass areas with subwavelength size with individually designed parameters. As a proof-of-concept, we propose the active phosphate fiber with the core consisted of two types of glasses doped with Yb3+ and Er 3+ ions, which exhibit independent performance. The presented phosphate fiber laser operates simultaneously at dual wavelengths at 1.04 μm and 1.535 μm with very good beam quality of M2=1.14 and slope efficiency of 23.0% and 9.8%, respectively. To our knowledge, this kind of fiber has not been demonstrated previously