Low loss and broadband low back-reflection interconnection between a hollow-core and standard single-mode fiber
Dmytro Suslov, Eric Numkam Fokoua, Daniel Dousek, Ailing Zhong, Stanislav Zvánovec, Thomas D. Bradley, Francesco Poletti, David J. Richardson, Matěj Komanec, Radan Slavı́k
Abstract
We report simultaneous low coupling loss (below 0.2 dB at 1550 nm) and low back-reflection (below −60 dB in the 1200-1600 nm range) between a hollow core fiber and standard single mode optical fiber obtained through the combination of an angled interface and an anti-reflective coating. We perform experimental optimization of the interface angle to achieve the best combination of performance in terms of the coupling loss and back-reflection suppression. Furthermore, we examine parasitic cross-coupling to the higher-order modes and show that it does not degrade compared to the case of a flat interface, keeping it below −30 dB and below −20 dB for LP 11 and LP 02 modes, respectively.