The LD-Cladding-Pumped High Power Tm³⁺-doped Silica Fibre Amplifying at Approximately 1.99 μm

A laser diode (LD) cladding-pumped cw Tm³⁺-doped silica fibre amplifier is reported that provides up to 3 W output with the slope efficiency nearly 30%. The gain fibre is 27.5/400 μm D-shaped Tm³⁺-doped silica double-cladding fibre, and the input signal sources is an LD-pumped Tm³⁺:YAP lasing at 1.99μm. The measured amplified spectrum only stretches a little relative to the input signal spectrum. This is the first report to the authors' knowledge of general experimental investigation of cladding-pumped Tm³⁺-doped fibre amplifier of high power cw at 1.99μm.