Refractive index sensor based on stress-induced long period grating

We proposed a novel refractive index sensor based on a side-polishing fiber to be cascaded with a stress-induced long period fiber grating (LPG), which is created by applying a force to a V-grooved plate on the single mode fiber with micro-bending deformation. When the refractive index (RI) surrounding the side-polishing surface is changed, the LPG-induced cladding mode light could be coupled back to the core mode, so that it will result in the magnitude variation of LPG loss-peak. This property of index sensing based on the stress-induced LPG by monitoring the power-level change may be exploited in chemical sensing and environmental monitoring applications.