Trial of measurement range extension in optical correlation-domain reflectometry based on double-modulation scheme

Abstract

Optical correlation-domain reflectometry (OCDR), widely recognized for its ability to pinpoint the locations and reflectivities of faulty connections and other reflective points along optical fibers, offers the advantages of random accessibility, real-time operation, and cost-effectiveness. In Brillouin OCDR, commonly employed for distributed strain and temperature sensing, a well-known challenge is the trade-off between spatial resolution and measurement range. To overcome this limitation, a double-modulation scheme has been introduced. Recent research has shown that this trade-off is also present in simplified OCDR systems without a frequency shifter, making it crucial to develop methods that can extend the measurement range while preserving spatial resolution. In this study, we experimentally validate the ability of the double-modulation scheme to effectively enhance the measurement range in simplified OCDR.