RF and Microwave Fractional Differentiator Based on Photonics

TLDR

The study introduces a photonic RF fractional differentiator constructed from an integrated Kerr micro‑comb source. The differentiator employs a 49‑GHz FSR Kerr micro‑comb to generate numerous comb lines, which are programmed and shaped with calculated tap weights, and its RF amplitude, phase, and temporal responses are experimentally characterized. Experimental results confirm that the device achieves arbitrary fractional orders from 0.15 to 0.90 over a 15.49‑GHz bandwidth, matching theory and demonstrating high performance, broad bandwidth, reconfigurability, and potential cost and size reductions.

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 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.