Ultrasensitive Refractive Sensor Based on Femtosecond Laser Inscribed Long-Period Fiber Grating With a Few Microcavities

• DOI: 10.1109/jlt.2023.3321787
• Publication Date: 2023-10-03T13:51:44Z
• Authors: Shan Gao; Yan Liu; Jing Yang; Zhenyu Duan; Taian Yin; Zhihai Liu; Jinhui Shi; Libo Yuan; Chunying Guan
• Keywords: Long-period fiber grating; Cladding (metalworking); Cladding mode; Fiber Bragg Grating

We experimentally demonstrate a single mode fiber (SMF) ultrasensitive refractive index (RI) sensor based on long-period grating (LPFG) with periodic microcavities fabricated by femtosecond laser. The liquid in the causes strong RI modulation to excite high-order cladding modes. proposed can operate reflection coating end face of gold film, as result cascade LPFG structure is equivalently formed increase contrast resonance dip. has an ultra-high sensitivity -12576 nm/RIU high linearity range 1.3335-1.3430 RIU and low temperature cross talk. promising applications biochemical or biomedical industries.