Monolithic Tm-doped single-mode fiber oscillator with 27.1 W output power at 1.94 μm

A single-mode monolithic continuous-wave fiber laser oscillator operating at 1.94 mu m with maximum output power of 27.1 W, using a 2.9 m single-mode thulium-doped silica fiber with 10 mu m core diameter, has been demonstrated. Sources of temperature rise and splice optimizing processing have been analyzed in detail to achieve near diffraction-limited beam quality (M-xy(2) < 1.1). A high slope efficiency with respect to incident pump power and narrow 3 dB bandwidth, of 55.5% and 0.046 nm respectively, has been determined. This fiber laser, with stable operation over 2 h, will be a promising candidate for medical and surgical applications.