An accurate de-multiplexing mathematical model is established for optical fiber Fabry-Perot(F-P)cavity and Fiber Bragg Grating(FBG)multiplexed sensor.The spectral characteristic of the sensor is analyzed and a new mechanism to separate FBG spectrum from F-P cavity spectrum is proposed.with a swept laser based wave length interrogator,the experimental results demonstrate that the cross interference between F-P sensor spectrum and FBG sensor spectrum is clearly eliminated,and the resolution of the sensor syst...