Photonics-based Simultaneous Angle of Arrival and Frequency Measurement for Multiple Targets Detection

Abstract

A photonics-based system for simultaneous angle of arrival (AOA) and frequency measurement of multiple targets is proposed. In the proposed structure, the optical carrier is split into two branches. In the upper branch, the optical carrier is injected into an optical frequency shift loop to generate an optical frequency-stepped local oscillator (LO). In the lower branch, the far-field RF signals captured by an antenna array are up-converted to optical domain by the Mach-Zehnder Modulators coupled to individual antennas respectively. The generated optical sidebands in each branch are then sent into a 90-degree optical hybrid, respectively. After balanced photodetection, the AOA and frequency can be derived from the generated low-frequency signals. An experiment of multiple targets detection is carried out, in which two incoherent microwave sources that work at the same frequency band can be distinguished in the angular direction.