Picosecond-pulse wavelength conversion based on cascaded sum-frequency generation/difference-frequency generation in PPLN waveguides

摘要

The wavelength conversion technique based on the cascaded sum-frequency generation/difference-frequency generation (SFG/DFG) process has an advantage of no pump occupation in the communication band, compared to the mostly adopted second-harmonic generation (SHG)/DFG process. In the SFG/DFG-based wavelength conversion, two pump waves and a signal wave are required. The pulsed wave, as a carrier of information, can be applied to the signal or one of the two pump waves. Though the converted wave has the form of pulses, its temporal and spectral characteristics are dependent on the arrangement of the input pulsed wave. Based on numerical simulation, the temporal and spectral characteristics of the pump, signal, converted and sum-frequency waves during their propagations in PPLN waveguides are systematically investigated in this work. In particular, temporal pulse shapes, optical spectra and conversion efficiency are emphasized and compared when picosecond pulse trains are used as the signal and pump waves, respectively.