Enhancement of SPR effect and sensing characteristics of no-core fiber with bubble structure

Abstract In this work, we propose the SPR fiber sensor based on a bubble structure. Conventional SPR optical fiber sensors have an anomalous broadening of the resonance dip in the near-infrared band. Therefore, we propose to utilize a bubble structure to improve the FWHM of the spectrum. The sensor utilizes no-core fiber as the sensing platform and multimode fiber as the transmission fiber, and fabricates a bubble at the fusion of the two fibers. The effect of bubble size on the SPR effect is investigated experimentally, and the results show that bubbles can improve the sensitivity and reduce the FWHM of SPR sensor. The refractive index sensing test was implemented on the proposed SPR bubble sensor. The experimental results showed that the bubble structure enhanced the maximum sensitivity of the SPR sensor by 927.7 nm/RIU. Finally, the effect of the bubble on the response time of the sensor is discussed. The method of using a bubble structure to improve sensor performance is simple to operate and easy to implement.