Abstract: The present invention relates to a precision phase mask for forming diffraction grating in optical fiber and optical waveguide, to provide them with nonlinear chirped grating for dispersion compensation use and having low fluctuation or crosstalk in the group delay characteristics. The diffraction grating is formed by means of interference fringe between diffracted lights of different orders, in which the cycle of the diffraction grating 20 increases nonlinearly, wherein plurality of diffraction gratings G1, G2, G3 . . . having different cycles are assembled on a plane in increasing order of the cycle with the directions of the diffraction gratings directed to the same direction, and assembled in such a manner that, where the cycle of grating changes nonlinearly and discontinuously, the regions having larger rate of change of the cycle contain proportionally more discontinuous phases per unit length.

Abstract: A chirp measurement apparatus includes a splitting section for splitting input signal light to two paths; a first dispersion medium with a total dispersion amount of +D (≠0) at a used wavelength, and a second dispersion medium with a total dispersion amount of −D (≠0) at the used wavelength;

Abstract: The invention relates to a process for the fabrication of an optical fiber-processing phase mask that is reduced in terms of pitch variations on the mask and stitching errors, and provides a process for the fabrication of a chirped type optical fiber-processing phase mask wherein a grating form of grooves provided in one surface of a quartz substrate is configured as an optical fiber-processing grating pattern. At an exposure step, writing data obtained by arranging and compiling a plurality of data for a repetitive groove-and-strip pattern while the pitch of repetition is modulated are used and an electron beam resist is provided on a phase mask blank, so that writing is carried out all over the writing area on said phase mask blank continuously in a vertical direction to said grating form of grooves.