(a) Schematic diagram of the nonlinear hybrid plasmonic waveguide. The rectangle nonlinear dielectric is LiNbO₃, the middle part is SiO₂, and the metal is silver. Structural parameters are as follows: w = h = 500 nm, gap = 10 nm. For a pumping wave at 890 nm, [ε_x, ε_y, ε_z](LN), =, [5.05, 5.05, 4.70], n_p = 1.875 + 1.473 × 10⁻⁴ i. For a signal wave at 1780 nm, [ε_x, ε_y, ε_z](LN), =, [4.87, 4.87, 4.54], n_s = 1.777 + 1.631 × 10⁻³ i. The simulated propagating fields of (b) the pump wave from the LN port and (c) the signal wave from the SiO₂ loaded silver port. The lateral field distributions of (d) the pump wave and (e) the signal wave correspond to the waveguide-like and the SPP-like hybrid modes, respectively.