One kilometer balanced analog photonic link based on a single multicore fiber

Abstract

A one kilometer balanced microwave photonic link based on a single four core multicore optical fiber is demonstrated for the first time, to the best of our knowledge. The radio frequency gains and differential phase stabilities over temperature were measured and compared to a conventional balanced link based on two spans of single mode fiber. Both the multicore fiber link and the single mode fiber balanced link exhibited differential phase fluctuations of |Δφ|≤13° at 25 GHz (corresponding to a differential delay or skew, |Δt|, of ≤1.4ps) under identical periodic temperature oscillations of ±13°C over a 60 min period. In contrast, previous studies have shown that two single mode fiber spans should have exhibited up to an order of magnitude greater Δφs compared to the multicore fiber. Our different results can be attributed to how the fibers are arranged; the previous works kept the two single mode fiber spans separate, on different spools, whereas in this work the two single mode fiber spans were co-located as close as possible together by spooling them ‘side-by-side’ onto a single mandrel, more representative of a balanced link in application. In addition, the radio-frequency crosstalk between the multicore fiber’s cores were measured, exhibiting acceptable levels at least 60 dB below the signal for all core combinations. The crosstalk is shown to be dominated by occurrences at localized points, e.g. at the multiplexers (fan-in/fan-outs) and splices, rather than during propagation. Regardless of the single mode fiber link’s performance, the measurements here demonstrate that multicore fiber-based balanced links are a viable single fiber alternative to conventional dual single mode fiber-based balanced links.