Splicing hollow core fiber with standard glass-core fiber with ultralow back-reflection and low coupling loss

Abstract

A main, yet-unsolved challenge in splicing hollow core fiber (HCF) into standard single mode fiber (SMF) system lies in managing the strong Fresnel back-reflection that occurs when the light travels from the empty core of the HCF into the glass core of the SMF or vice-versa. This impacts the performance of the system due to effects such as multipath inter-ference. Here, we demonstrate a new technique that combines angle-cleaving the HCF, which reduces the back-reflection with offset splicing the mode-field adapter to the SMF, which compensates for the refraction at the glass-air interface, enabling us to achieve low coupling loss. We first analyze this novel configuration via simulations and show that it is possible to achieve a coupling loss that is comparable to a conventional flat-cleaved splice. Subsequently, we fabricate an SMF-HCF connection with loss of 0.6 dB prior to arcing (1.2 dB after splicing) and ultralow back-reflection (-64 dB) by applying an optimized 4.5° angle and 5 µm offset. To the best of our knowledge, this is the first low insertion loss spliced SMF-HCF connection where a widely acceptable level of back-reflection of < -60 dB is achieved.

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Identifiers

ORCID for Bo Shi: orcid.org/0000-0003-0895-3052

ORCID for Meng Ding: orcid.org/0000-0003-3654-8660

ORCID for Francesco Poletti: orcid.org/0000-0002-1000-3083

ORCID for Radan Slavík: orcid.org/0000-0002-9336-4262

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