A dispersion compensator includes at least one first optical waveguide, a first slab waveguide, an arrayed waveguide connected to the at least one first optical waveguide via the first slab waveguide, a second slab waveguide, at least one second optical waveguide connected to the arrayed waveguide via the second slab waveguide, and a phase distribution provider configured to provide a phase distribution to the arrayed waveguide.