Power-efficient Triple-cladding Coupled 4-core Fibre Amplifier

Inhalt:
We propose a triple-cladding multi-core amplifier to achieve a high core-to-cladding ratio with a reduced number of cores while maintaining a feasible cladding diameter. Our 4-core amplifier demon-strates the highest power conversion efficiency of 7.2% among reported C-band amplifiers with less than ten cores.