To provide an optical filter module having good adjacent crosstalk and distributed characteristics and suitable for a DE-MUX.
Four gratings 5a-5d are arranged in an optical fiber 3 to form a grating forming area 6, and the reflected light wavelengths of gratings 5a-5d are made mutually different for every predetermined set interval. Optical isolators 1, 2 are connected to the optical incident side and emission side of the grating forming area 6. The optical isolator 1 of the optical incident side is made into a reflected light cutoff means to interrupt reflected light reflected by the gratings 5a-5d among incident light having a plurality of mutually different wavelengths made incident on the grating forming area 6 from returning to the optical incident side. Light having a waveband which passed all the gratings 5a-5d among the incident light is selectively emitted from the optical emission side of the grating forming area 6. This realizes a DE-MUX application module.
SHINOZAKI ATSUSHI
SHIRASAKA ARIO
