All-optical frequency chirp magnification based on four-wave-mixing for optical comb generation

An efficient optical comb generation method based on degenerated four-wave-mixing process in highly nonlinear fibre is demonstrated. The all-optical processing of the frequency chirp is wavelength tunable and thus enables the capability of tunable chirp magnification. The magnification of the frequency chirp with a factor tunable from two to five has been demonstrated. An optical comb with 22 sub-carriers has been obtained which refers to a bandwidth of 210 GHz, about five times the bandwidth of 40 GHz for the original signal.