Low-loss Fan-in/Fan-out Devices Based On Multi-Cladding Bridge Fibers

The increasing demands for communication have revealed the capacity limitations of traditional single-mode fibers (SMFs). Thus, multicore fiber(MCF) based on spatial division multiplexing(SDM) technology has attracted significant attention, which can provide higher capacity for optical communication. To fully leverage the potential of MCF, designing efficient fan-in/fan-out (FI/FO) devices to introduce or extract multiple independent optical signals into or from the MCF is crucial. In this paper, we propose a multi-cladding structured bridge fiber to minimize coupling loss between single-mode fibers and MCF. The coupling loss between the bridge fiber and SMF is measured at an impressively low value of 0.07 dB. By employing the fused taper technique on the fabricated bridge fiber, we successfully develop a seven-core fiber FI/FO device. The average insertion losses of FI/FO device are 0.56 dB and 0.58 dB, respectively. While the inter-core crosstalk is impressively less than −51.0 dB. The device has promising application prospects in fiber sensing, optical interconnect and high-capacity communication.