Single-mode 212 W tapered fiber laser pumped by a low-brightness source

Abstract

With a tapered double-clad all-glass ytterbium fiber as a gain medium, a maximum output power of over 200 W at 1079 nm and a slope efficiency of over 70% were demonstrated. The tapered double-clad fiber concept allows for using low-brightness diode bars and results in cost-effective and efficient high-power fiber lasers. The adiabatic conical fiber gain waveguide combines improved pump absorption owing to enhanced mode mixing in the pump cladding, low-noise single fundamental mode operation with M(2)< or =1.02, and strong potential for significant power scaling.

750-W double-clad ytterbium tapered fiber laser with nearly theoretically limited efficiency

“…For a conventional double clad fiber the brightness gain factor K DCF can be written as: 2 (1) where S is the slope efficiency of the laser, A clad , A core , NA clad , NA core are areas and numerical apertures of the cladding and the core in the double clad fiber respectively and D clad and D core are the cladding and core diameters.…”

“…Recently we have proposed active tapered double clad fibers as a gain medium for high power fiber lasers and amplifiers [1][2][3][4] . Having very large clad diameters, these fibers allow exploiting high-power, low-brightness laser diode bars as a pump source.…”

High-power single-mode tapered double-clad ytterbium fiber laser pumped by diode-laser bar

“…1a. Eventually, the propagation angle exceeds the critical angle for total internal reflection, resulting in pump leakage into the secondary cladding, which is known as the vignetting phenomenon 3,4 . We consider the propagation of meridional rays through a taper whose diameter has a linear dependence on the axial length L, with the diameters of the wide and narrow ends being D 1 and D 2 , respectively (Fig.…”

“…Recently, we have proposed an active tapered double-clad fiber (T-DCF) as a gain medium for high power fiber lasers and amplifiers [1][2][3] . T-DCF was shown to have several distinct advantages as compared with regular fibers, particularly, it can be pumped with low brightness sources and offers an efficient intrinsic mode mixing mechanism resulting in enhanced pump absorption and robust single mode generation.…”

“…,(3) and(4)we can obtain an equation for the number of meridional ray reflections in a the total number of reflections in a linear taper, one should integrate Eq.…”