The present invention provides a method and apparatus for controlling the detailed strain field imposed on a guided-wave Bragg grating. The spectral and temporal form of radiant energy traveling down optical fibers is important in many fields, including communications and sensing. The spectral distribution and center wavelength of short optical pulses is of particular importance. In the communication field the information carrying capacity of an optical fiber can be limited by the dispersion experienced by short pulses as they propagate along an optical fiber. Chirped fiber optic intracore Bragg gratings can be used to compensate for this dispersion. However, a grating with a different degree of chirp would be required for each particular communication system. This control of the intra-grating strain distribution allows the grating to be tuned over a broad spectral range or chirped in a manner that permits it to compensate for a wide range of dispersion with or without a shift in the grating center wavelength. In addition, precise control of the strain distribution along a grating can be used to manufacture a variety of spectral filters.