RF and microwave fractional differentiation with transversal filters
using a soliton crystal microcomb multiwavelength source
Abstract
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
response as well as the temporal response 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 reduced sized and cost.