We design a novel kind of polarization beam splitter based on a gold-filled dual-core photonic crystal fiber (DC-PCF). Owing to filling with two gold wires in this DC-PCF, its coupling characteristics can be changed greatly by the second-order surface plasmon polariton (SPP) and the resonant coupling between the surface plasmon modes and the fiber-core guided modes can enhance the directional power transfer in the two fiber-cores. Numerical results by using the finite element method show the extinction ratio at the wavethlengths of 1.327 µm and 1.55 µm can reach −58 dB and −60 dB and the bandwidths as the extinction ratio better than −12 dB are about 54 nm and 47 nm, respectively. Compared with the gold-unfilled DC-PCF, a 1.746-mm-long gold-filled DC-PCF is better applied to the polarization beam splitter in the two communication bands of λ = 1.327 µm and 1.55 µm.

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A high sensitivity of photonic crystal fiber (PCF) with a tunableliquid core refractive index sensor based on surface plasmon resonance (SPR) induced bythe symmetric metal films is proposed in this paper. The SPR excitation materials are chose as gold and silver. The transmission characteristics and sensing performance of the SPR-PCF sensor with different geometrical parameters were analyzed by using finite element method (FEM) and Maxwell equation. The final results show that when thediameter of the central hole is 1.6µm and the thickness of the gold film is 40nm, the SPR occurs at the wavelength of 1400nm, and the confinement loss can reach 17398dB/m. The average sensitivity of the SPR-PCFsensor can reach 7200nm/RIU, and the linear fitting constant is R2=0.99959, which is expected to have important applications in the direction of liquid refractive index detection.