Refractive index sensing using addressed fiber Bragg structures with etched section

Abstract This work proposes a novel fiber-optic sensing approach for detecting variations in the external refractive index using an addressed fiber Bragg structure with two π -phase shifts and a etched cladding section. The cladding removal significantly enhances the sensitivity of the effective refractive index of the guided mode to changes in the environment. A detailed spectral analysis is carried out, incorporating temperature effects. The results show that variations in the effective refractive index induce a shift in one of the high-Q transmission peaks, leading to a monotonic change in the address frequency, which can be detected using microwave photonic techniques. The proposed method enables the design of highly sensitive and spectrally selective refractive index sensors with addressability and temperature stability, making it promising for multiplexed biochemical and environmental monitoring applications.