Performance characteristics of 5-bit optical Receive beamformer

This paper describes implemented methods for characterizing a 5-bit programmable dispersion matrix (PDM) that is built to control a two-channel Receive beamformer in the 1550 nm region. The architecture of the PDM, is based on an array of 5 delay lines each having two spliced fiber Bragg gratings. Phase measurements for 32 possible delay configurations of the PMD are presented. Beam-patterns of this Receive beamformer at RF frequencies of 0.2, 0.5 and 1 GHz agrees well with the theoretical calculations. The main lobe of the beam pattern is shown to be independent of frequency for several target positions thus demonstrating a “squint-free” characteristic of this optical processor.