“Switchable Red, Blue-Green emission using polarized optical fibre loop mirror in upconversion Pr3+/Yb3+-doped ZBLAN fibre laser system.”

This manuscript experimentally demonstrates a switchable upconversion visible fibre laser system. The laser system is based on a linear fibre laser cavity with Praseodymium-Ytterbium codoped fluorozirconate (ZBLAN) optical fibre as a gain medium. The fibre laser cavity integrates a fibre loop mirror with a polarization controller to switch between multiple visible spectra. The optical fibre laser source provides dual blue and green emission with a centered wavelength of 490 nm and 520 nm, as well as red emission with a bandwidth of 115nm, from orange to deep red with peaks centered at 605nm, 635 nm, 693 nm, and 715 nm. The mentioned emissions can be switched and combined to generate almost pure white emission, white emission with high deep-red contribution, and vivid red. In addition, it demonstrated visible emission separation in an upconversion laser system via polarization, generating a wideband switched red-blue-green light source.