A wavelength division coupler capable of dividing and coupling at least three wavelengths is provided. The wavelength division coupler includes a first waveguide having a first end and a second end, a second waveguide having a third end and a fourth end, in which a section between the third end and the fourth end is located adjacently to one end of the first waveguide to form a mode coupling section for dividing or coupling an input light, and a Bragg zone having a Bragg grating in the mode coupling section formed in portions of die first waveguide and the second waveguide.