The optical ring is a non-reciprocal, multi-port optical passive device. Its core function is that optical signals can only be transmitted in one direction from the port to the terminal in a specific order.

In modern optical communication networks, fiber optic couplers play a crucial role. It is like an invisible "traffic command", silently completing the distribution and combination of optical signals in scenarios such as 5G base stations, data centers, and optical fiber sensing, supporting high-speed and efficient information transmission networks.

With the acceleration of the implementation of 5G-A (5G-Advanced), AI computing power clusters, and East Digital and West computing projects, optical communication networks are facing three core challenges: ultra-high bandwidth, ultra-low latency, and ultra-long-distance transmission. In this context, the polarization mode dispersion (PMD) problem of traditional single-mode fibers has become a bottleneck that limits performance, and PM fiber components are becoming a key enabling technology in high-speed coherent communication, quantum communication, silicon-optical integration and other fields with their unique polarization maintenance capabilities.