A Kilowatt All-Fiber Cascaded Amplifier

Abstract

A kilowatt all-fiber cascaded amplifier is demonstrated with a distributed side-coupled cladding-pumped Yb-doped fiber for the first time, to the best of our knowledge. Two-stage cascaded amplification is realized in the amplifier, with a total output power of 1.009 kW and an optical-to-optical efficiency of 76.8% with respect to launched pump power. The output beam quality of the cascaded amplifier is also measured, and the M <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> factor is ~2.1. The results illuminate that the cascaded amplifier should be beneficial to the power scalability of fiber laser systems.