Dispersion engineered sum-frequency generation in a periodically poled thin-film LiNbO3 nanowaveguide

Nanoscale periodically poled lithium niobate (LiNbO 3 ) waveguides with cross-sectional area below 1 μm 2 have recently enabled nonlinear frequency up-conversion of light with ultrahigh efficiencies [1] . Such ultra-compact nanophotonic waveguides also allow extensive control over the dispersion properties of their guided modes which has been exploited to realize broadband phase-matched nonlinear optics and supercontinuum generation [2] . In this work we experimentally demonstrate type-II quasi phase-matched sum frequency generation (SFG) in a dispersion engineered nanowaveguide. We explicitly show that the phase matching condition for SFG can be tailored by controlling the group indices of the guided modes through optimal design of the waveguide. Also, we contrast the phase matching condition for this type-II process with that of a type-0 mode-matched SFG process occurring in the same waveguide to clearly distinguish the role of dispersion engineering in nonlinear wavelength conversion processes in nanowaveguides.