The optical fiber grating and the manufacture method of the same

The present invention relates to the optical fiber grating and the manufacture method of the same, and more particularly to the art of the optical fiber grating which with small secular variation and low cost, in which heating the optical fiber which having core with residual stress, along the length direction of the fiber intermittently for softening the clad around the core, in this way, the residual stress is released for varying the refractivity of the core, in the optical fiber grating thus made, the refractive index difference between the core and the clad is periodly varied along the length direction of the fiber. Accordingly, the optical fiber grating with stable secular variation can be made with high efficiency without by high price apparatus.