Single-Frequency 336 W Spliceless All-Fiber Amplifier Based on a Chirally-Coupled-Core Fiber for the Next Generation of Gravitational Wave Detectors

Specialty fibers such as chirally-coupled-core show a high potential for further power scaling of single-frequency fiber amplifiers. For the first time, we demonstrate spliceless all-fiber amplifier, where all optical components are directly integrated in single Yb$^{3+}$-doped 3C-fiber. Such laser design enables compact and robust architecture using specialty fibers, while maintaining excellent beam properties. At an output 336 W operating at 1064 nm, fundamental mode content 90.4% polarization extinction ratio above 13 dB was measured without any impact transverse instabilities or other parasitic effects. This work emphasizes field applications 3C-fibers high-power systems.