High-power mid-infrared supercontinuum laser source using germania-doped fiber

Abstract

In this work, a high-power all-fiber mid-infrared (MIR) supercontinuum (SC) laser source was generated in a short piece of centimeter level germania-doped fiber (GDF). The MIR SC generation in GDF was pumped by a 2 μm chirped pulse amplification (CPA) system. The seed source was a passively mode-locked oscillator by semiconductor saturable absorber mirror (SESAM) with a pulse width of 29.7 ps, a spectrum width of 0.3 nm and a fundamental repetition rate of 44.31 MHz. A high-power pump source with a spectral coverage of 1.9~2.2 μm was obtained in thulium-doped fiber amplifier (TDFA). Adopted by 19 cm-long 64 mol. % GDF, we obtained a broadband SC source spanning from 1850 to 3000 nm. The generated SC had a maximum output power of 31.2W with a pump slope efficiency from 56.2% to 30.9%. By optimizing fusion-spliced parameters, a high optical coupling efficiency was obtained between single-mode fiber (SMF) and GDF. In addition, we measured the pulse characteristics of SC laser source in different peak power of pumping source and different length of GDF. It paved the way for further realization of high power and wide spectrum MIR SC laser source.