A tunable repetition rate multiplier for multi-wavelength optical pulse trains

Abstract

We propose a temporal Fresnel filtering based repetition rate multiplication (RRM) scheme suitable for multi-wavelength optical pulse trains. Residual chirp terms inside and outside the temporal Fresnel integral contribute to preserving of the multi-wavelength feature. Implementation of our scheme is very simple and compact, and only one linearly chirped Bragg fiber grating (LCBG) and one temporal grating (TG) are needed. Optical signals before and after the TG share the same LCBG by forward and backward passing to implement temporal original and inverse Fresnel transforms, respectively, avoiding possible mismatch between these two transforms and minimizing the influence of the third and higher order dispersion coefficients. Electrical programming of the TG contributes to the tunability of multiplication factor m. In numerical simulations, our scheme succeeds to preserve the multi-wavelength feature of an input pulse train, while the current temporal Fourier filtering and temporal Talbot effect based schemes fail, verifying the novelty of our scheme. Our work is especially useful for tuning the scanning resolution of steering angles of microwave beams, formed by photonic-assisted phased array antennas, in the application of five-generation (5G) wireless communications.