Photonic heterodyne mixing for angle of arrival estimation without direction ambiguity

Abstract

Photonic methods for angle-of-arrival (AOA) estimation have been widely proposed to achieve high-precision measurements over a wide bandwidth, aiming to overcome the limitations of traditional electronic methods. In this paper, we propose and experimentally verify a photonic heterodyne mixing approach for unambiguous estimation of angle-of-arrival (AOA). By employing optical down-conversion and reference phase comparison, our system effectively resolves phase ambiguity, achieving a 360°phase measurement range and extending the angle-of-arrival (AOA) measurement range to ±90°(180°total). The heterodyne mixing process enables simultaneous frequency estimation and phase discrimination, offering a dual-function solution for modern radar and wireless communication systems. Based on the experimental results, our system demonstrates an estimation error of less than 5.2°within the range of 0°to 360°and less than 2.8°within the range of ±100°.