Sensitivity amplification of bubble-based all-silica fiber liquid-pressure sensor by using femtosecond laser exposure

摘要： We proposed an efficient and universal sensitivity amplification method for most kinds of sensors based on fiber in-line two-beam Fabry–Perot interferometers (FPIs) by using the femtosecond laser exposure. As an example of two beam FPI, a liquid-pressure sensor based on a micro-bubble at the end of the single mode fiber (SMF) was fabricated. To improve the sensitivity, a third refection mirror in SMF near the bubble at a certain distance was fabricated by using femtosecond laser exposure. As a result, the Vernier effect is generated, which improves the pressure sensitivity from ?0.414 nm/MPa to ?3.973 nm/MPa. Besides, the synchronous measurement of liquid-pressure and temperature can be achieved by monitoring the interference peak and the Vernier envelope at the same time.