Picosecond-pulse wavelength conversion based on SHG nonlinear interaction in a PPMGLN waveguide

Second harmonic generation (SHG) in a periodically poled MgO-doped lithium niobate (PPMGLN) waveguide is studied using a tunable pulsed pump source composed of a mode-locked fiber ring laser and two tunable filters. In the experiment, the lasing wavelength can be tuned from 1530 to 1579 nm, and the pulse width can be tuned from 2 to 7 picoseconds at 40 GHz. Second-harmonic pulses are generated when the picosecond pump pulses pass through the PPMGLN waveguide. SHG conversion efficiency versus pump pulse width, pump power, and pump wavelength is investigated experimentally. Propagation behaviors of both pump and SHG pulses are then numerically simulated. Based on the temporal and spectral characteristics of conversion, a quantitative analysis on SHG efficiency is presented. The simulation results are in good agreement with the experimental data.