Characteristics of novel tail ring-shaped cascaded long period fiber grating sensor

Abstract In this paper, a novel tail ring-shaped cascaded long period fiber grating (TR-CLPFG) sensor is fabricated by connecting two LPFGs with ring-shaped optical fiber. The results show that the sensor can effectively reduce full width at half maxima (FWHM) and improve refractive index sensitivity. The parallel fibers in the ring-shaped structure make the two LPFGs almost identical and improve the fabrication efficiency. The smaller the sensing area leads to fewer samples to be measured. The TR-CLPFG sensor has compact structure, which is conducive to its application in narrow space. In addition, this U-shaped structure allows the sensor to be inserted into the solution measurement, which changes the previous measurement methods of LPFG sensor and makes the sensor more flexible in application. In general, this novel TR-CLPFG sensor not only maintains the advantages of traditional linear cascaded long period fiber grating (CLPFG) sensor, but also gets many superiorities in the fabrication process and application. This TR-CLPFG sensor has great potential in future detection applications.