Excessively Tilted Fiber Grating Sensors

The development of excessively tilted fiber gratings (Ex-TFGs) provides a new type of sensing device with high refractive index (RI) sensitivity, low thermal crosstalk and vector sensing property. Due to the asymmetric grating structure of Ex-TFG, the light in the core is coupled into high order forward-propagating cladding modes and split into two orthogonal polarization states, resulting in dual-peak resonances in the transmission spectrum. The Ex-TFG also exhibits a non-circularly symmetrical near field distribution, which endows an exceptional orientation sensing capability. Benefitting from the unique mode coupling behavior, Ex-TFGs have been studied and developed for many different sensing applications, such as polarization dependent torsion and loading sensors, vector accelerometer and magnetometer, and a variety of low thermal crosstalk bio/chemical sensors. This paper will review the recent study and development of Ex-TFGs in terms of mode coupling mechanism, fabrication method, transmission and sensor characteristics and the novel applications in sensing areas.

Automated summary

The development of excessively tilted fiber gratings (Ex-TFGs) has provided a new type of sensing device with high refractive index sensitivity, low thermal crosstalk, and vector sensing properties. These gratings have unique advantages such as dual-peak resonances and exceptional orientation sensing capability. Due to their specific mode coupling behavior, Ex-TFGs have been used for various sensing applications, including polarization dependent torsion sensors, vector accelerometers, and low thermal crosstalk bio/chemical sensors.