Proposal for all-optical format conversion based on a periodically poled lithium niobate loop mirror

We propose and simulate two novel schemes of 40 Gbit/s format conversion from non-return-to- zero to return-to-zero based on cascaded second-harmonic generation and difference-frequency generation in a periodically poled lithium niobate loop mirror. We investigate the conversion performance, including eye diagrams, conversion efficiency, pulse width, Q-factor, extinction ratio, and tunability. The proposed schemes can perform single-to-dual-channel format conversion. In addition, it is found that simultaneous multichannel format conversion as well as tunable multicasting format conversion can potentially be implemented with great flexibility. (c) 2007 Optical Society of America.