Remote‐Head Optical Correlation‐Domain Reflectometry Using Kilometer‐Scale Fibers

Optical correlation‐domain reflectometry (OCDR) provides distributed reflectivity measurements with moderate range, high spatial resolution, and real‐time capability. Conventional systems, however, rely on bulky instruments that hinder field use. We propose and experimentally demonstrate a remote‐head OCDR, where only the fiber under test (FUT) and circulator are placed on‐site, connected to the main system via kilometer‐scale fibers. The reflectivity distribution of the FUT was clearly measured, with multiple reflection points detected and ~ 15 cm spatial resolution maintained. These results confirm the feasibility of remote‐head OCDR and its potential for practical infrastructure monitoring. © 2026 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.