Measurement of differential mode group delay in few-mode fiber with correlation optical time-domain reflectometer

A measurement system of differential mode group delay (DMGD) in few-mode fiber with correlation optical time-domain reflection was proposed. A photonic lantern used in the system can be utilized for mode separation and selection and can generate six LP modes: LP₀₁,LP₁₁,LP₁₁,LP₂₁,LP₂₁, and LP₀₂. The signal reflected by the end of the fiber is correlated with the data sequence sent, which realizes the single-ended measurement of 5 km few-mode fiber DMGD. This method is not destructive for detecting fiber transmission systems and is simple and easy to implement. It can be used for detecting fiber transmission characteristics in the mode-division multiplexing communication system.