Fiber grating sensor is sensitive to temperature and strain.To improve its accuracy as a strain sensor

a triangle notch filter has been designed to realize single-parameter measurement of fiber grating strain

which utilizes the falling and rising edges of the reflective spectrum of the fiber Fabry-Pérot（FFP） interferometer

and influence of temperature on cross-sensitivity is effectivelyeliminated.The advantage of the project is that principle is simple and realization is easy.The error of strain is ±4 ×10

-6

in the temperature range of-20

7

0 ℃

and it can meet a demand for the parameter in bradge measurement.