Nd3+ doped phosphate glass optical fibre lasers

In this thesis a Nd3+-doped phosphate glass was developed in-house in order to obtain a glass stable, robust, able to incorporate high amount of RE ions and suitable for fibre drawing. Several Nd3+-doped phosphate glass samples were fabricated by doping the developed host glass with concentrations of Nd3+ up to 10 mol%. The samples were then characterized in order to measure their physical, thermal and spectroscopic properties. The effect of Nd3+ doping concentration on emission spectra and lifetimes was investigated in order to study the concentration quenching effect on luminescence performance. With the aim to fabricate a Nd3+-doped double cladding (DC) optical fibre laser emitting at 1.06 µm, three different phosphate glasses using a custom designed glass composition, were fabricated. By changing properly the concentration and constituents present in our phosphate glass, the refractive indexes of the three glasses were adjusted in order to obtain an adequate numerical aperture between core and inner cladding, and between inner and outer cladding, while maintaining similar thermo-mechanical properties in view of the fibre drawing process. A Nd3+-doped DC optical fibre was fabricated by preform drawing using a drawing tower facilities available in the research group laboratory. Morphological and optical characterisation of the fibre were carried out in order to evaluate fibre quality. In order to optimize Nd3+-doped fibre laser design, a numerical analysis of the lasers was performed. At last, a CW cladding pumped fibre laser based on 9 cm of fabricated Nd3+-doped optical fibre was experimentally demonstrated.