Research On Sensitivity Amplification And Multi-parameter Simultaneous Measurement Of Fiber F-P Sensor

Fiber-optic Fabry-Perot(F-P)sensor is simple,which is through the dual-beam interference to conduct parameter measurement.The(F-P)sensor has characteristics of small size,high sensitivity,simple structure,simple preparation,in more and more fields playing a role.The fiber sensor is developing towards the direction of high sensitivity and multi-parameter simultaneous measurement.Vernier effect is a good method to increase the sensitivity of fiber optic sensors.Cascaded F-P cavities can be used for multi-parameter measurement.There are three cavities in this type sensor based on the traditional Vernier effect.In this paper,the spectral composition of cascade F-P cavities is studied,which is another development of cascaded F-P cavities sensor.This paper simulates the traditional Vernier effect spectrum and analyzes the reason for the interference term in the Vernier effect spectrum caused by the cascaded F-P cavities.The disturbance term in the spectrum results in different sensitivity between the upper envelope and the lower envelope,with the inconsistent positions of the upper envelope and the lower envelope.All of these can be removed after the interference is removed,which providing good experience for envelope fitting of this kind of sensor.In this paper,the Vernier effect was tested by capillary and single-mode optical fiber to realize the sensitivity amplification of silica cavity.In view of the problems caused by the fixed structure of traditional cascade cavity Vernier effect sensor,such as difficulty in preparation,single magnification rate and untunable sensitivity,this paper proposes a separate double F-P cavities sensor based on multiplicative Vernier effect.The sensor is mainly used to cascade two F-P cavities on the optical path through two circulators,so that the two F-P cavities are separated in space,and their reflection spectra are multiplied to realize Vernier effect.This kind of structure can easily replace the reference cavity,realizing the tunable sensitivity amplification.