Novel photonic true-time-delay beamformer based on the free-spectral-range periodicity of arrayed waveguide gratings and fiber dispersion

A novel optical beamformer based on the spectral periodicity of arrayed waveguide gratings (AWGs) and dispersive fiber is proposed. This architecture uses multiple sets of wavelengths with a spectral spacing among the signals on each set equal to the free spectral range of the AWG in such a way that all the wavelengths of each set are routed to the same AWG port and pass through the same fiber length in order to obtain multiple simultaneous delays. A wavelength-to-antenna element correspondence is established so fiber dispersion will introduce an equal delay amongst signals of the array elements. This architecture presents straightforward multibeam capability. Experimental results demonstrating the feasibility of the delay line are presented.