Limits of Supercontinuum Generation in Highly GeO₂ Doped Fibers Pumped by Noise-Like Pulses

Broadband supercontinuum generation in highly GeO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> doped fibers holds significant appeal for researchers due to their distinct advantages. In this study, we propose employing a low repetition rate noise-like pulse mode-locked fiber laser as the pulse seed for mid-infrared supercontinuum generation in such fibers. Utilizing only one amplifier stage to amplify the noise-like pulse, we achieved a broadband supercontinuum with a 20 dB bandwidth spanning from approximately 652 nm to 3350 nm in a highly GeO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> doped fiber with a core GeO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> concentration of 98%, even with an output power as low as 297 mW. To the best of our knowledge, this represents the widest supercontinuum achieved in highly GeO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> doped fibers to date. Two others highly GeO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> doped fibers were used to generate a broadband supercontinuum spanning from the visible to the mid-infrared as well. Notably, our experiments revealed that the fiber damage of these highly GeO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> doped fibers poses a limiting factor for further broadening of the supercontinuum. It was demonstrated that the power density of fiber damage decreased with increasing GeO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> concentration. This study marks the first instance of highly GeO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> doped fiber damage due to high peak power pump pulses in supercontinuum generation. It holds significant reference value for the research on supercontinuum generation based on highly GeO<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> doped fibers.