Gap solitons supported by mode hybridisation in Lithium Niobate nano-waveguides

Nano-waveguide platforms have been developed over the past decade providing strong field enhancement and allowing precise control of modal dispersion [1] . Such nano-waveguides produced from materials with strong quadratic (χ (2) ) nonlinearity make excitation of χ (2) temporal solitons feasible [2] . Compared with Kerr solitons, χ (2) solitons have tighter dispersion criteria making nano-waveguides the only practical method for their observation [2] , [3] . As seen in previous work in photonic crystal fibres [4] , mode hybridisation, which occurs generally in waveguides with rectangular (or close to rectangular) cross-section, provides conditions to study novel types of soliton and their dynamics.