All-Silica Fiber Ultra-Flat 2-3 μm Supercontinuum Source Based on Highly Nonlinear Silica Fiber

Abstract

In this letter, we demonstrated an all-silica fiber 1.5- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3.2 ~\mu \text{m}$ </tex-math></inline-formula> supercontinuum (SC) source based on germanium-doped highly nonlinear fibers (HNLF). By optimizing the length of HNLF, as the pump injected into the HNLF increased to 6 W, a 4.12 W broadband SC source extending from 1516 to 3182 nm was obtained. The 3 dB spectrum bandwidth was up to 1022 nm ranging from 1855 nm to 2877 nm, and the 1 dB bandwidth was up to 878 nm covering from 1959 nm to 2837 nm. To the best of our knowledge, this is the flattest SC in the 2- <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3 ~\mu \text{m}$ </tex-math></inline-formula> region based on doped silica fiber to date.