AUTHORS:

Peterka P., Aubrecht J., Pysz D., Franczyk M., Schreiber O., Kamrádek M., Kasik I., and Buczyński R.

ABSTRACT:

We present the pedestal-free thulium doped silica fiber with a large nanostructured core optimized for fiber lasers. The fiber is composed of over 6 thousand thulium doped silica nanorods with a diameter of 71 nm each which form a nanostructured step-index core. We study the influence of non-continuous distribution in nanoscale active areas on gain, beam quality, and fiber laser performance. The proof-of-concept fiber is effectively single mode for wavelength above 1.8 µm. We demonstrate the performance of the fiber in a laser setup pumped at 792 nm. Single mode laser emission with a slope efficiency of 29% at quasi-continuous output power of 4 W with M²= 1.3 at the emission spectrum 1880-1925 nm is achieved.

Optics Express, 2023, vol. 31(26), pp. 43004-43016, doi: 10.1364/OE.503047