Generation of Repetition-Rate-Quadrupled Optical Pulse Trains Using a PolM or a Pair of PolMs

Two approaches are proposed for generating repetition-rate quadrupled optical pulse trains using a polarization modulator (PolM) or a pair of PolMs. In the first approach, a PolM is used in conjunction with a dispersive element (i.e., a chirped fiber Bragg grating). In the second approach, a pair of PolMs which are connected in parallel are employed. The fundamental principle in achieving repetition-rate quadrupling is the periodic suppression of three consecutive optical spectral lines of a phase-modulated light wave. A proof-of-concept experiment is performed in which a return-to-zero pulse train having a repetition rate of 13.6 GHz is generated when a sinusoidal signal at 3.4 GHz is applied.