All-Optical Demultiplexing Using LiNbO3 Quasiphase-Matched Wavelength Converters

All-optical demultiplexing based on the cascaded χ(2) process in a LiNbO3 quasiphase-matched wavelength converter is studied. Based on the obtained fundamental pulse width dependence of the normalized second harmonic generation (SHG) efficiency, it is predicted that efficiency of the cascaded χ(2) wavelength conversion can be enhanced greatly using a pump light with a short pulse. This prediction is verified by an experimental demonstration of demultiplexing from 40 GHz to 10 GHz. Despite the low average pump power (∼ 1 mW, 3.4 ps pulse width) used in this experiment, conversion efficiency as high as -17 dB was obtained. It is also found that the broadening of the converted pulse width is negligible in the present demultiplexing method.