Photonic true-time delay unit for broadband adaptive nulling in antenna arrays

An Opto-VLSI-based (VLSI: very-large-scale-integration) tunable true-time delay (TTD) generation unit used for adaptive null steering in phased array antennas is presented. The system is based on continuous tunable optical TTD technique. Arbitrary multiple true-time delays to generate multiple broadband nulls can simultaneously be synthesised for each antenna element. The proposed structured are characterised both theoretically and experimentally. Experimental results demonstrating the principle of the true-time delay for null generations are presented. The maximum time delay measured for a wavelength tuning from 1530 to 1560 nm is 9.5 ns.