Optical up-conversion on continuously variable true-time-delay lines based on chirped fiber gratings for millimeter-wave optical beamforming networks

An electrooptical up-converting modulation scheme has been considered on chirped-fiber-grating-based (CFG) true-time-delay lines for optical beamforming networks. A rigorous analytical study about the effect of both the up-conversion process and CFG dispersion on the amplitude and delay of detected signal is presented. Simulations and measurements show that the bandwidth limitation of the delay line due to the fiber grating dispersion is clearly improved if compared to the conventional intensity modulation scheme, while the time-delay performance over a 2-30 GHz bandwidth is maintained (σ_max =±1 ps). This new concept is used on an optical beamforming network architecture for a millimeter-wave (15-25 GHz) phased array antenna showing a promising performance