Exploiting dispersion of higher-order-modes using M-type fiber for application in mid-infrared supercontinuum generation

M-type fibers have the exceptional property that the higher-order LPOn modes are core-confined and easily excited, while the LP01 and other modes are confined to a high-index ring surrounding the core, so they are not easily excited. This has profound consequences for mid-infrared supercontinuum sources, where the high zero-dispersion wavelength of chalcogenide and ZBLAN fibers means that exotic pump sources have so far been necessary. We show here that in chalcogenide and ZBLAN M-type fibers the lower ZDW of the core-confined higher-order LP02 mode can be in the range of 2 to 3 mu m (around 1.55 mu m), while the fiber still has a large core diameter and thus supports high average power. This will allow established pump laser technology to be used in future high-power mid-infrared supercontinuum sources.