Optical and THz Integrated Circuits for Mode-Dependent Free-Space Communications

Abstract

Free-space optical and THz communication systems have gained increasing interest in various applications. In such systems, simultaneous transmission of multiple orthogonal spatial modes, each carrying an independent data channel, can enhance the aggregate data rate. Due to the potential of lower size, weight, and power consumption, integrated circuits might play an important role in future deployments of mode-dependent free-space optical and THz links. In this article, we review various photonic and THz integrated circuits for mode generation/detection and (de)multiplexing in mode-dependent free-space optical and THz links. Three integrated structures, including micro-ring, antenna-array, and pixel-array structures, and their key properties (e.g., tunability, ability for multiplexing, and bandwidth) are discussed.