Liquid-cooled 24 W mid-infrared Er:ZBLAN fiber laser

Abstract

A $24\mathrm{W}$ liquid-cooled CW $3\mu \mathrm{m}$ fiber laser with a multimode-core Er-doped ZBLAN fiber has been developed. The output power of $24\mathrm{W}$ and an optical-to-optical efficiency of 14.5% (with respect to incident pump power) were obtained with $975\mathrm{nm}$ diode pumping. Efficient cooling was implemented by a combination of fluid cooling over the entire length of the fiber and conductive cooling at both end faces of the fiber. Consequently, stable high-power operation was demonstrated. To our knowledge, this is the highest output power obtained by a $3\mu \mathrm{m}$ fiber laser. Furthermore, the high power can be further scaled up, since the output power in the present work is limited only by the available pump power.