With the development communication, polarization filter, as the key components of communication, becomes more and more important. For satisfying various requirements, the paper studies different photonics crystal fiber (PCF) polarizing devices based surface plasmon resonance (SPR). Besides, we have also demonstrated their excellent polarization performance from two aspects of theory and experiment. On one hand, the paper theoretically proposed dual-wavelength single polarizing filter with the broadband of low crosstalk. It could have single polarizing filtering in the dual-wavelength of 1310 and 1550 nm and the polarization direction of optical output is independent of the wavelength of incident light. The polarization direction of emergent light through filter can always keep the core mode in x-polarized direction (x-PCM) in a wide range of wavelength, which increases the difference of confinement loss of core mode in y-polarized direction (y-PCM) and x-PCM, and reduces mutual crosstalk. On the other hand, considering the new communication waveband emerging, we present a V-type birefringence microstructure optical fiber with embedded dual copper wires that were made by the stack-drawing method and the dual copper wires were aligned in the vertical direction symmetrically. Experimental results showed that the fiber can be easily excited strong SPR in the S and L waveband. Then the core mode is completely coupled into the copper wires and generates the SPR in the y-polarized direction, to achieve the purpose of directional filtering.
With the rapid development of life science, multi-component detection is necessary. In order to monitor the concentration of the biochemical substances simultaneously, a dual-channel biomedical sensor is proposed in this paper. Due to its sensitivity to the surrounding refractive index, there are many applications in biochemical sensing. Surface plasmons are a coupling of electromagnetic oscillations generated by electromagnetic waves and free electrons at the interfaces between metal and dielectrics. Taking into account the different plasma band of different metals, multiple signal peaks can be generated during detection to achieve multi- peak sensing. In addition, when rough analysis is performed on the analysis sample, In order to avoid the complex process of specific sample extraction, multi-component detection of the sample is necessary. Moreover, research on a micro-structured optical fiber sensor based on the plasmon mode interaction of Au/Ag films has been rarely reported. Therefore, a novel dual-channel sensor is designed considering the flexible characteristics of Photonics crystal fiber (PCF) structure, different plasma bands for Au/Ag, and the necessity of multi- component detection. The numerical results show that the core mode in PCF sensor is affected by the Surface plasmon resonance (SPR) at the Au/Ag interface simultaneously, which makes it possible to monitor multiple substances near the Au/Ag films. Meanwhile, the detection of the positive and negative amplitude sensitivities makes the sensor detection stable and it can eliminate certain external disturbances. Its excellent sensing characteristics are of great application value in environmental monitoring, biochemical sensing, etc.