High-Precision and Synchronous Measurement of Fiber Length and Dispersion Using Optical Frequency Comb-Based Time-Delay Dispersion Interferometry.

Optical fiber is the cornerstone of the contemporary inter-network and has produced profound and far-reaching effect on modern information society ever since it was invented. The detection of key parameters of optical fiber such as length, refractive index and chromatic dispersion is of great significance to ensure the quality and security of communication network. Here, a synchronous, fast and high-precision measurement method for the length and dispersion of optical fibers is proposed, where the time-of-flight measurement and spectral interference are organically combined using an optical frequency comb (OFC) with the assistance of a modulated narrow linewidth single frequency laser. The length and the dispersion coefficient distribution can be preciously obtained directly and simultaneously by measuring only single frame interference spectrum. The excellent time-frequency characteristics of the optical frequency comb and our unique algorithm enable the realization of extremely high measurement accuracy and resolution: a resolution of 10 μm @ 500 m, and an accuracy of 1.5 cm (1.364×10 ^-6 relatively) @ 11 000 m, as well as a dispersion measurement accuracy of 0.5%. The method boasts rapid measurement, ample bandwidth, elimination of scanning, and exceptional precision, making it highly applicable in both optical communication and optical fiber sensing systems.