Optical Beamformer Based on Diffraction Order Multiplexing (DOM) of an Arrayed Waveguide Grating

A simplified beamforming architecture using a wavelength-selective optical true time delay (OTTD) module is proposed for phased array antenna (PAA) systems. Based on diffraction order multiplexing of an arrayed waveguide grating (AWG), the beamformer can realize multiple simultaneous time delays with only one OTTD module. We design, fabricate, and characterize a compact integrated optical beamformer using this structure for an eight-element X-band PAA system. The time delays generated by the fabricated beamformer are measured to be in the range from 0 to 278 ps in 5.7 ps increments of eight diffraction orders. The measured overall variation in the insertion loss of this device is less than 1.85 dB from 1527 to 1607 nm. The experimental results demonstrate that the proposed architecture can offer many advantages, such as multibeam capability, low insertion loss, a small footprint, and high resolution.