Programmable integrated photonic coherent matrix: Principle, configuring, and applications

Every multi-input multi-output linear optical system can be deemed as a matrix multiplier that carries out a desired transformation on the input optical information, such as imaging, modulation, and computing. The strong programmability of the optical matrix has been explored and proved to be able to bring more flexibility and greater possibilities to the applications such as optical signal processing and general optical digital and analog computing. Furthermore, the burgeoning integrated photonics with advanced manufacturing and light manipulating technology pave the way for large-scale reconfigurable photonic coherent matrix. This paper reviews the programmable photonic coherent matrix in the integrated platform. First, the theoretical basis and optimizing methods of three types of integrated photonic coherent matrix (Mach–Zehnder interferometer mesh, multi-plane diffraction, and crossbar array) are introduced. Next, we overview the configuring method of this optical matrix. Furthermore, their applications in optical signal processing, optical neural network, optical logic operation, recurrent optical matrix acceleration, and optical quantum computing are comprehensively reviewed. Finally, the challenges and opportunities of programmable integrated photonic coherent matrix are discussed.