A Pr³⁺-doped ZBLAN fibre upconversion laser pumped by an Yb³⁺-doped silica fibre laser

An Yb³⁺-doped silica fibre laser pumped at 840 nm has been used to provide the two pump wavelengths, 840 nm and 1020 nm, required for pumping a Pr³⁺-doped ZBLAN fibre upconversion laser. The performance of the upconversion laser at 491, 520 and 635 nm is presented, with measurements of fibre loss at 635 nm and 520 nm which indicate that fibre losses are an important factor limiting the performance of the upconversion laser.