Single mode laser oscillation in an Nd-doped large core double clad fiber cavity with concatenated adiabatic tapers

We created a new design for an Nd-doped clad-pumped silica fiber laser to enhance the pump absorption and lasing efficiency for a butt-coupled, end-pumped scheme. Two concatenated adiabatic tapers formed within the laser cavity simultaneously removed higher order modes and were spliced to conventional single more fibers. We theoretically analyzed mode propagation along the composite cavity and experimentally achieved continuous wave oscillation in the LP₀₁ mode at 1.06 μm and a laser output power of over 820 mW with a slope efficiency of 27%.