Transparent Microwave Photonic Filter Based on Brillouin Losses in Optical Fiber

TL;DR

This paper introduces a low-noise, tunable microwave photonic filter using stimulated Brillouin scattering in optical fiber, achieving wide bandwidth tuning, flat-top response, and minimal noise, enhancing existing filter technologies.

Contribution

The paper presents a novel SBS-based microwave photonic filter with bandwidth tunability from 500 MHz to 10 GHz, flat-top response, and low noise, surpassing traditional SBS gain filters.

Findings

Bandwidth tunable from 500 MHz to 10 GHz

Achieves flat-top response with 0.3 dB ripple

Exhibits minimal noise with no detectable noise pedestal

Abstract

In this paper, we propose a low-noise, bandwidth tunable microwave photonics filter (MPF) based on stimulated Brillouin scattering (SBS) losses. By suppressing the out-of-band signal with two broadened symmetric SBS losses, pass bandwidth can be tuned from 500 MHz to 10 GHz. Considering the limited interaction in the center frequency range, a flat-top response with 0.3 dB ripple is easily achieved. Unlike a SBS gain based filter, due to the transparency of the pass band in our proposed filter, hardly no noise is detected in a noise measurement against an obvious maximum 5 dB noise pedestal for a SBS gain based one. Considering the wide independent bandwidth and center frequency tunability, flat-top response, and low-noise characteristic, our proposed filter can be perfectly used as a supplement of most commericalized tunable single bandpass filters, whose minimum bandwidth is limited by 10 GHz.