Patent attributes
A slope gain equalizer that corrects a slope of a gain characteristic of an optical signal in a predetermined wavelength bandwidth. An interference filter, which allows insertion losses in a predetermined wavelength region to be inclined in opposite directions between a transmitting direction and a reflecting direction from a short wavelength side to a long wavelength side, is arranged between a dual-core fiber collimator and a single-core fiber collimator facing each other on an optical axis. An optical signal of a predetermined bandwidth inputted from a first or second optical fiber held by the dual-core fiber collimator is reflected by the interference filter and outputted from the second or the first optical fiber. An optical signal inputted from a third optical fiber held by the first optical fiber or the single-core fiber collimator is transmitted through the interference filter and outputted from the third or the first optical fiber.