Patent ID: 6853771

Claim:
An apparatus and method for compensation of central wavelength shifting of a fiber grating by material with Invar effect, comprising: a substrate having a negative thermal expansion coefficient; and a fiber having a first portion and a second portion fixed on the substrate and a third portion located between the first portion and the second portion, the third portion having the fiber grating; the substrate and the fiber having a temperature compensation equation expressed as: α eff λ bragg =K λ A f E f (α c −α f ) wherein: α eff is an effective thermal expansion coefficient of the fiber grating; α bragg is a Bragg wavelength; K λ is a constant; A f is a cross-section area of the fiber; E f is an elastic modulus of the fiber; α c is the negative thermal expansion coefficient of the substrate; and α f is a thermal expansion coefficient of the fiber.