Investigation of a balanced microwave photonic link utilizing a single few-mode fiber

A balanced microwave photonic link, which utilizes mode-division multiplexing in order to combine both of its optical paths into and out of a single six-mode few-mode fiber, is demonstrated for the first time, to the best of our knowledge. Due to non-negligible modal crosstalk, the link exhibited excess radio-frequency gain fluctuations when compared to an equivalent conventional balanced link. The LP₀₂+LP₀₁ mode pair was the most stable with 2σ (two standard deviations) fluctuations of 0.4 dB about the average link gain, compared to the conventional link's 2σ of 0.16 dB. The excess crosstalk-induced fluctuations may render the link impractical to use outside of the laboratory.