Fig. 1: Adapted poling difference frequency generation (DFG).
From: Integrated broadband and high-efficiency difference frequency generation
a Schematic illustration and principle of the DFG device based on a thin-film PPLN waveguide. b Cross-section of thin-film PPLN waveguide. c Image of the thickness measurement system. d Measured thickness (dashed) and corresponding poling period (solid) distributions along the PPLN waveguide.
