Multi-kilometer Long, Longitudinally Uniform Hollow Core Photonic Bandgap Fibers for Broadband Low Latency Data Transmission

The low intrinsic nonlinearity and low signal latency characteristic of Hollow Core Photonic Bandgap Fibers (HC-PBGFs) have fueled strong interest for data transmission applications. Whereas most research to date has looked at improving the optical performance of HC-PBGFs (e.g., reducing the loss, increasing the transmission bandwidth and achieving well-tempered modal properties through the suppression of surface mode resonances). In this study, we address the challenging problem of scaling up the fabrication of these fibers to multi-kilometer lengths-an indispensable step to prove this fiber technology as viable. We report the fabrication of low loss, wide bandwidth HC-PBGFs operating both in the conventional telecoms window (1.55 μm) and in the predicted region of minimum loss (2 μm), in lengths that substantially exceed the state of the art. At 2 μm, we obtained a 3.85 km long fiber with ≈3 dB/km loss and >160 nm wide 3 dB bandwidth. Additionally, we report an HC-PBGF operating at 1.55 μm with a length of just over 11 km, transmission bandwidth in excess of 200 nm and a longitudinally uniform loss of ≈5 dB/km, measured via cutback and an integrated scattering method. We used the latter fiber to demonstrate error-free, low-latency, direct-detection 10 Gb/s transmission across the entire C-Band as well as 20 Gb/s quadrature phase shift keyed transmission. These represent the first demonstrations of data transmission over a length of HC-PBGF exceeding 10 km.