An apparatus includes a slider mounted on an arm, a first waveguide including a first core guiding layer, a second waveguide mounted on the slider and including a second core guiding layer having a uniform thickness smaller than the thickness of the first core guiding layer, and a coupler for coupling light from the first core guiding layer to the second core guiding layer, wherein the coupler comprises a curved mirror formed in the second waveguide and positioned to reflect light from the first core guiding layer into the second core guiding layer.