Proposal of correlation-dip-based optical correlation-domain reflectometry

Conventional distributed measurement methods that employ correlation-domain techniques typically use a “correlation peak” as the measurement point. In this work, we propose and experimentally demonstrate a novel form of optical correlation-domain reflectometry that targets the “correlation dip,” located between two correlation peaks. As the reflected spectrum observed at the correlation dip exhibits its maximum bandwidth, we can selectively detect the reflection from the fiber under test by measuring the power in that broad frequency band. We verify the basic operation of this technique experimentally.