PHASE MASK FOR MACHINING OPTICAL FIBERS, AND ITS FABRICATIONMETHOD

摘要

A phase mask for machining optical fibers, which allow easy electron beam drawing of the phase mask whose recessed groove pitch changes according to positions. On the side of a transparent substrate are formed a plurality of repetitive grating-like patterns (A1-A3) of grooves (26) and ridges (27), and the light refracted by the patterns are projected onto an optical fiber to create a grating in the optical fiber by the interference fringes produced by the refracted lights of different orders. The pitch of the grooves increases or decreases linearly or nonlinearly, and the width ratio between the grooves (26) and the ridges (27) is constant. The phase mask is manufactured by arranging a plurality of patterns of grooves (26) and ridges (27) of different pitches and performing the electron beam drawing.