Accurate Measurement of Propagation Delay in a Multi-Span Optical Link

The principle of Correlation Optical Time Domain Reflectometry (C-OTDR) is proposed to accurately measure the propagation delay over a multi-span optical fiber link. The delay of the transmission fiber is measured in the reflective mode, while uni-directional node components are measured in a transmissive mode. Delimiting reflectors are required between the sections for accurate demarcation.Comment: 2019 International Topical Meeting on Microwave Photonics (MWP), Ottawa, Canad

Monitoring of Optical Networks Using Correlation-Aided Time-Domain Reflectometry with Direct and Coherent Detection

We report on methods to monitor the transmission path in optical networks using a correlation-based OTDR technique with direct and coherent detection. A high probing symbol rate can provide picosecond-accuracy of the fiber propagation delay, while a sensitive phase detection with a high repetition rate allows the monitoring of dynamic effects in the vicinity of the fiber. We discuss various approaches to evaluate the measured traces and show the results of a few monitoring applications.Comment: Invited paper to OECC 2023, Shanghai, July 2-6, 202

Acoustic Sensing after 50 km of Transmission Fibre using Coherent Optical Subassembly

A coherent optical subassembly (COSA) is evaluated for coherent-correlation optical time domain reflectometry (CC-OTDR) based fibre sensing. Even though the COSA was originally designed for digital communication applications, acoustic signals with frequencies up to 360 Hz can be detected after 50 km of transmission.Comment: This work has received funding from the Horizon Europe Framework Programme under grant agreement No 101093015 (SoFiN Project) and was partially funded by the German Federal Ministry of Education and Research in the framework of the RUBIN project Quantifisens (Project ID 03RU1U071D

Improvement of accuracy for measurement of 100-km fibre latency with Correlation OTDR

We measured the latency of a 100 km fibre link using a Correlation OTDR. Improvements over previous results were achieved by increasing the probe signal rate to 10 Gbit/s, using dispersion compensation gratings, and coupling the receiver time base to an external PPS signal.Comment: This work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 762055 (BlueSpace Project

Characterization of Multi-Core Fiber Group Delay with Correlation OTDR and Modulation Phase Shift Methods

Using a Correlation-OTDR and a modulation phase shift method we characterized four multi-core fibers. The results show that the differential delay depends on the position of the core in the fiber and varies with temperature.Comment: This work has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No 762055 (BlueSpace Project

Hollow-core fiber characterization with correlation-optical time domain reflectometry

Using a Correlation-OTDR, we characterized the temperature-induced group delay variations of two nested antiresonant nodeless hollow core fibers. The temperature sensitivity of both is substantially less than for SSMF with some dependency on coating type.</p