A temperature compensating device for optical fiber gratings includes first and second expansion members having different coefficients of thermal expansion. The expansion members are elongated in a direction parallel to the fiber grating and levers are secured to both ends of the expansion members. Each lever has a first end flexibly secured to a respective end of the first expansion member and a middle portion flexibly secured to a respective end of the second expansion member. The other end of each lever is secured to a respective end of the fiber grating. The expansion members, the levers and the fiber grating all lie substantially in a single plane. There is also disclosed a package for holding four of the temperature compensating devices in two rows of two devices each, with their fiber gratings adjacent each other so that when viewed in a plane orthogonally to the longitudinal axes of the fiber gratings, the fiber gratings are each at a respective corner of a rectangle.