[en] Optical sensors, such as fiber interferometers transmit along light paths and perform measurements based on optical path difference. These types of sensors can reduce device volume and improve sensing performance using optical multiplexing. A beam splitter for optical path multiplexing in an optical fiber ring is proposed. A photonic crystal was used to design the beam splitter. By optimizing and improving the photonic crystal microstructure, the beam splitting function can be realized while taking into account the cycling capability. Therefore, the light can recirculate multiple times in the fiber ring to realize light path multiplexing. The finite difference time domain method is used to analyze and evaluate the performance of the beam splitter.

[en] This paper proposes a high strength and low loss splicing method suitable for coupling between hollow-core photonic crystal fiber and single mode fiber, based on filament fusion technology. The essence of this method is keeping the temperature of the single mode fiber above the melting temperature, and that of the hollow-core photonic crystal fiber at around the softening point temperature by modifying several splice parameters, which can be pre-evaluated by numerical simulation. Experimental results have verified the accuracy of the numerical model, and ideal splicing results can be made under proper splice parameters. In this paper, repeatable splicing between hollow-core photonic crystal fiber and single mode fiber with a loss of less than 2.3 dB, and a strength higher than 38 Kpsi is demonstrated. (paper)