A Multi-Channel Multi-Bit Programmable Photonic Beamformer Based on Cascaded DWDM

We propose and experimentally demonstrate a novel multi-channel multi-bit programmable photonic beamformer, which consists of multiple parallel photonic true-time delay (PTTD) subnetworks based on cascaded DWDMs. Each PTTD subnetwork can provide multi-bit true-time delays (TTDs) for a multi-channel modulated RF signal of a phased array antenna (PAA) and operate over a wide RF range from 10 MHz to 12 GHz. The RF signal is modulated to a spectrally separated laser array combined by a DWDM to form a multi-channel spatially separated PAA. The multi-bit TTDs for scanning PAA angles are rapidly programmed by means of a control circuit of optical switches in the PTTD subnetwork. By using an optical splitter, multiple parallel PTTD subnetworks can be topologically configured out for a PAA with a large number of elements. The obtained radiation patterns demonstrate that the proof-of-concept experimental result agrees well with the theoretical analysis, verifying the feasibility of the proposed photonic beamformer.