Abstract
An in-band pumping technique that employs low numerical aperture (NA) and high brightness fiber lasers emitting at 1018nm enables outstanding power scaling performance by increasing pump power handling capacity of fiber components, reducing thermal load and quantum defect. Here, we present design criteria for an in-band pumped fiber master oscillator power amplifier (MOPA) structure, pumped with 1018nm fiber lasers, as well as mitigation strategies for nonlinear effects for scalable single-mode laser operation at multi-kilowatt power levels. In addition, we report experimental demonstration of an in-band pumped MOPA with an output power scaling up to 4.63kW and a slope efficiency of ∼88%. The MOPA system is pumped by 18×264W high brightness fiber lasers operating at 1017.8±0.3n m with an NA of <0.075. The laser emits at 1080.4nm wavelength with a stimulated Raman scattering suppression of >36.8d B and has a near-diffraction-limited beam quality of M 2∼1.61. To the best of our knowledge, our laser has the highest brightness of 153G W⋅c m -2⋅s r -1 reported at 1080nm in co-pumping configuration.
Published Version
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