Angle-Spliced SMF to Hollow Core Fiber Connection with Optimized Back-Reflection and Insertion Loss

We study and demonstrate angle-cleaved fusion splicing between single mode fiber (SMF) and nested anti-resonant node-less fiber (NANF). First, we analyze the trade-off between the connection loss and back-reflection suppression. Subsequently, we angle-cleave and splice connections with selected parameters, demonstrating a connection loss of 1.25 dB (0.6 dB higher than for a flat-cleaved connection) and back-reflection below −40 dB (as compared to −15 dB for the flat-cleaved connection). The measured spliced connection loss is only slightly higher (0.2–0.3 dB) than that predicted due to the angle cleave and the mode field mismatch. This was achieved mainly thanks to accurate angle-cleaving and an improved offset splicing technique that we have developed. We characterized the prepared SMF-NANF spliced connections with a range of techniques, evaluating the connection loss, unwanted coupling to the LP ₁₁ mode, and back-reflection. Finally, we show how the reduced back-reflection can improve the performance of a communication system through reduction of round-trip induced multipath interference.