A Broadband Optical Fiber Coupler Based on Dual-Hollow Core Fiber

Abstract

Abstract Hollow fiber has become a research hotspot in the field of special fibers for its excellent characteristics, such as low loss, low delay, low dispersion, and low nonlinear coefficient. Due to the lack of fiber coupler matching hollow core fiber, the application development of hollow core fiber in the all-fiber integrated system is greatly hindered. Dual-core fiber is widely used in the development of fiber couplers because it can choose optical power, wavelength, and polarization state by the coupling between the two cores. For the urgent need for hollow core fiber coupler, the design and research of wideband fiber coupler based on dual-hollow core fiber are carried out in this paper. Based on the coupled mode theory, the theoretical correlation between the structural parameters and the coupling length in the dual-hollow core anti-resonant fiber was analyzed by using the COMSOL simulation software system. On this basis, a 50:50 wideband fiber coupler was designed by adjusting the structural parameters to reduce the coupling length and introducing the sleeve into the cladding pipe to reduce the loss. The bandwidth of the coupler is up to 150 nm and the transmission loss is on the order of 10 −2 dB/m.