Microfiber sensor probe integrated with a cascaded Fabry-Perot interferometer

Developing micrometer-nanometer size optical fiber sensors has promising application prospects in microenvironments, such as biological cells, micro robots, and microfluids. We propose a new strategy to fabricate a microfiber sensor probe (MSP). A femtosecond laser was applied to integrate cascaded Fabry-Perot interferometers (FPIs) into a silica microfiber. And a MSP with diameter of similar to 8 mu m, extinction ratio of 15 dB, fitness of 24.6, and Q-factor of 2310 was demonstrated in the experiment. In addition, theMSPwas applied for the refractive index and thermal measurement and the sensitivity was observed to be 10 pm/degrees C and 18.5 nm/RIU. The two-beam approximation model was applied to analyze the spectrum, and simulations were taken to research the refractive index sensitivity influenced by the fiber size. (C) 2021 Optical Society of America

Automated summary

This study presents a new strategy for fabricating microfiber sensor probes and demonstrates high sensitivity in refractive index and thermal measurements. The use of a femtosecond laser to integrate FPIs into a silica microfiber shows promising results for microscale sensing applications.