Enhancement of butt-coupling pump efficiency in a new Nd-doped large core double clad fiber laser cavity adiabatically tapered at both ends

摘要

Summary form only given. A new clad pumped fiber laser cavity structure has been proposed and experimentally demonstrated. Double adiabatic tapers included in the cavity provided inherent highly mode-selective attenuation to the lasing photons guided through the core with an improved butt-coupling efficiency for the pump light. Filtering of high order modes at the lasing wavelength was confirmed by measurement of the far-field pattern of the laser output. Output power 820 mW was achieved for the coupled pump power of 5.8 W which could be further improved by reduction of helical waves in pump light.