SECONDARY FUNCTION TYPE OPTICAL WAVEGUIDE GRATING. PHASE MASK AND DISPERSION SLOPE COMPENSATION CIRCUIT

PROBLEM TO BE SOLVED: To easily and reproducibly make a secondary function type optical waveguide grating that a grating pitch is changed nearly secondary function-ally for the distance of the optical waveguide in the longitudinal direction, and to compensate collectively the dispersion and dispersion slopes of respective wavelength components of an optical signal by using it without demultiplexing the wavelength multiplexed optical signal by wavelength classifications. SOLUTION: The secondary function type optical waveguide grating 5 is constituted so that the grating pitch is changed secondary functionally along the longitudinal direction, and by combining the secondary function type optical waveguide grating 5 with an optical circulator 4 and a 3dB coupler, etc., without using an optical demultiplexer, an optical wavelength multiplexer and plural dispersion compensating fibers, a dispersion slope compensation circuit is constituted, and the dispersion value and the dispersion slope are compensated together by it.