Dispersion effects of fiber Bragg gratings on true-time-delay beamforming networks

Fiber Bragg gratings (FBGs) are key components in wideband true-time-delay beamforming networks. Different time delays are obtained when an RF modulated optical signal is reflected by an array of FBGs located at different physical locations of an optical delay line. In this paper, we report the study of dispersion effects of uniform FBGs on FBG-based true-time-delay beamforming networks. The RF signal is modulated on an optical carrier using double-side-band (DSB) modulation and single-side-band (SSB) modulation. The results indicate that the time delay performance is affected greatly by the dispersion induced by the FBGs. The results also show that the dispersion effect is reduced by four times if an SSB modulation scheme is employed.