Cascaded nonlinear down-conversion in poling-free lithium niobate nanophotonic waveguides.

ABSTRACT: While cascaded second-order nonlinear processes have revolutionized shorter-wavelength light generation through up-conversion, their potential for longer-wavelength emission via parametric down-conversion remains fundamentally unexplored - constrained by narrow phase-matching bandwidths, insufficient parametric gain and stringent requirements on complex poling. Here, we break this paradigm through a reverse-polarization dual-layer lithium niobate nanophotonic waveguide that achieves broadband phase matching and record 15.3% conversion efficiency for mid-infrared (MIR) generation. Pumped at 1.03 μm, the cascaded optical parametric generation and difference frequency generation processes produce dynamically tunable MIR emissions spanning 2.06-3.09 μm - a relative bandwidth of 40%. By strateg

SUBMITTER: Yan C 

PROVIDER: S-EPMC12615627 | biostudies-literature | 2025 Nov

REPOSITORIES: biostudies-literature