High-index-ring three-layer fibres for mode-locked sub-1.3 μm fibre lasers

This paper addresses issues pertaining to the propagation of ultrashort pulses in the cavities of mode-locked sub-1.3 mu m fibre lasers. We demonstrate that multimode high-index-ring three-layer optical fibres operating on a single higher order HE1m mode are an effective approach to dispersion compensation. We present optimal parameters of the refractive-index profile in such fibres, which ensure zero first- and second-order chromatic dispersion coefficients at 1.06 mu m for the HE12 and HE13 modes, and analyse their dispersion and power parameters.