Hybrid-structure 1018-nm monolithic single-mode fiber laser producing high power and high efficiency

A hybrid-structure setup comprising single-mode and few-mode gain fiber concurrently to acquire high-power single-mode light with high efficiency was demonstrated. Using this setup, a 1018 nm continuous-wave fiber laser based on ytterbium-doped fibers stably outputted 300 W and 1.19-M2 with an optical-optical efficiency of 79.3% at the highest output. The stable output power was 36% higher than the previously highest report at this wavelength using 10-µm-core-diameter double-cladding YDFs. The beam quality was uncompromised while the efficiency was 5% higher. Amplified spontaneous emission was suppressed as 45-dB lower than the lasing peak. Control experiments were also made to demonstrate the advantages, of which the performances also reached the highest records.