Red and green light generation in TPPLNOI ridge optical waveguide with 1550 nm picosecond laser

Periodically poled lithium niobate (PPLN) waveguides are a powerful platform for efficient frequency conversion. Conventional frequency doubling PPLN converters only generate second-harmonic light. However, we propose a trapezoidal periodically poled lithium niobate on insulator (TPPLNOI) ridge optical waveguide, simultaneously generating red and green light with 1550 nm picosecond laser by cascading second-harmonic generation and sum-frequency generation (SHG-SFG). According to the experimental data, we find that the second-harmonic (red light at 775 nm) and third-harmonic (green light at 517 nm) power increase with the pump light (1550 nm) power. We also verify experimentally that temperature can affect nonlinear frequency conversion of cascading SHG-SFG, and when the temperature increases from 20 degrees C to 70 degrees C, the normalized conversion efficiency of red light and green light rises from 154.79% W-1 cm-2, 129.24% W-1 cm-2 to 204.29% W-1 cm-2, 152.08% W-1 cm-2, respectively.