We report a photonic radio frequency (RF) fractional differentiator based on an integrated Kerr micro-comb source. The micro-comb source has a free spectral range (FSR) of 49 GHz, generating a large number of comb lines that serve as a high-performance multi-wavelength source for the differentiator. By programming and shaping the comb lines according to calculated tap weights, arbitrary fractional orders ranging from 0.15 to 0.90 are achieved over a broad RF operation bandwidth of 15.49 GHz. We experimentally characterize the frequency-domain RF amplitude and phase responses as well as the temporal responses with a Gaussian pulse input. The experimental results show good agreement with theory, confirming the effectiveness of our approach towards high-performance fractional differentiators featuring broad processing bandwidth, high reconfigurability, and potentially greatly reduced size and cost.
@article{arxiv.2001.03420,
title = {Optical Kerr soliton crystal microcomb source for RF photonic fractional differentiation},
author = {Mengxi Tan and Xingyuan Xu and Bill Corcoran and Jiayang Wu and Andreas Boes and Thach G. Nguyen and Sai T. Chu and Brent E. Little and Roberto Morandotti and Arnan Mitchell and David J. Moss},
journal= {arXiv preprint arXiv:2001.03420},
year = {2020}
}