ALL-FIBER SIDE-PUMPED TAPERED AMPLIFIER OF THE ps-PULSES

This paper presents the results of an optimization process conducted on an all-fiber ps-pulse amplifier with sub-MW peak power, operating at a wavelength of 1064 nm, with a final amplifying stage based on a ytterbium-doped tapered fiber. The double-cladded active fiber was counter-pumped through the side surface. Two tapered fibers, with maximum core and cladding diameters of 39/375 and 58/625 µm, were utilized (in both cases, the thin part of the tapered fibers was single-mode with a geometry of ~8/80 µm). The optimal profile of the pump-feeding fiber was determined, the high-power unstable fixation polymer was eliminated, and a tapered fiber with an additional narrowing at the output end was used to compensate the increased numerical aperture of the injected pump. As a result, 42 W of average power was obtained with 9 ps pulse amplification, and the maximum achieved peak power was 0.62 MW.