Experimental investigation of nonlinear process based on cSHG/DFG in PPLN waveguide

Effects of second harmonic generation (SHG) and cascaded second harmonic generation/difference frequency generation(cSHG/DFG) based on the quasi-phase-matching (QPM) condition in periodically poled lithium niobate (PPLN) waveguide were investigated experimentally. SHG conversion efficiency of -13.6.dB and QPM bandwidth of 0.45.nm were achieved using a 16.1.dBm power of fundamental wave at 1.550.4.nm. Using pulsed all-fiber passive mode locked laser and tunable continuous wave laser, cSHG/DFG effect utilized for optical sampling was observed. Conversion efficiencies were calculated, and 11.88.nm-wide QPM bandwidth was achieved through changing the wavelength of input signal. Conversion efficiency of cSHG/DFG effect increased linearly with the total injected power.