PHASE MASK FOR MACHINING OPTICAL FIBERS, AND ITS FABRICATIONMETHOD

摘要

The invention relates to an optical fiber-processing phase mask which enables a phase mask with a groove pitch varying in a position-dependent manner to be easily obtained by electron beam writing, and its fabrication method. In the optical fiber-processing phase mask comprising on one surface of a transparent substrate a repetitive pattern of grooves (26) and strips (27) located in a grating form, so that an optical fiber is irradiated with diffracted light according to the repetitive pattern to make a diffraction grating in said optical fiber by an interference fringe of diffracted light of different orders, a plurality of patterns (A1 to A3) having a linearly or nonlinearly increasing or decreasing pitch are juxtaposed, with a constant width ratio between the grooves (26) and the strips (27). The phase mask is fabricated by carrying out writing while the groove-and-strip patterns with a different pitch are juxtaposed.