Integrated silicon photonic true-time delay beam-former for wide-band phased-array antenna

Conventional electronically-steerable phased-array antenna systems suffer from increasingly complicated control schemes to allow for narrowband RF steering. A phased array antenna architecture was previously presented which provides for wideband steering using a simplified control scheme requiring only one analog control parameter for steering along one dimension. A cascaded architecture of slow-light-based true-time delay gratings within an silicon photonic integrated circuit (PIC) enable the C-band optical carrier wavelength to serve as this control parameter for an X-band radio-frequency signal. Fabrication of this beamformer PIC was carried out using the American Institute for Manufacturing (AIM) Photonics foundry. Thermal sensitivity of the slow-light gratings and directional couplers on the PIC were investigated, and packaging solutions were evaluated, including integrated doped-silicon heaters to compensate for fabrication variations. A homodyne phase-tracking technique is employed to further characterize the slow-light performance of the beamformer, allowing for phase-sensitive measurements near the band-edge of the slow-light gratings.