All-optical wavelength conversion: The next challenge

The fast wavelength-tunable all-optical wavelength converters for optical crossconnects in next-generation wavelength division multiplexing (WDM) networks is discussed. They are based on difference-frequency mixing in a periodically poled lithium niobate (PPLN) and shows conversion efficiencies of more than 40% (4 dB conversion loss). There efficiency improves by channel waveguides imprinted in the lithium niobate crystal. The results shows that the optical switching and wavelength-conversion functions can be integrated within a single component by using lithium niobate for making wavelength-selective fast optical switches.