Comb-Based Radio-Frequency Photonic Filters with Rapid Tunability and High Selectivity

TL;DR

This paper presents a novel RF photonic filter approach using frequency combs, achieving rapid tunability (~40 ns), high selectivity, and reconfigurability for advanced radio-frequency systems.

Contribution

It introduces a new comb-based RF photonic filter method enabling fast tuning and high selectivity, overcoming previous implementation challenges.

Findings

Achieved RF passband tuning in ~40 ns speed.

Demonstrated Gaussian filter lineshapes with >60 dB sidelobe suppression.

Realized >70 dB stopband attenuation.

Abstract

Photonic technologies have received considerable attention for enhancement of radio-frequency (RF) electrical systems, including high-frequency analog signal transmission, control of phased arrays, analog-to-digital conversion, and signal processing. Although the potential of radio-frequency photonics for implementation of tunable electrical filters over broad RF bandwidths has been much discussed, realization of programmable filters with highly selective filter lineshapes and rapid reconfigurability has faced significant challenges. A new approach for RF photonic filters based on frequency combs offers a potential route to simultaneous high stopband attenuation, fast tunability, and bandwidth reconfiguration. In one configuration tuning of the RF passband frequency is demonstrated with unprecedented (~40 ns) speed by controlling the optical delay between combs. In a second, fixed filter configuration, cascaded four-wave mixing simultaneously broadens and smoothes comb spectra, resulting in Gaussian RF filter lineshapes exhibiting extremely high (>60 dB) main lobe to sidelobe suppression ratio and (>70 dB) stopband attenuation.