A waveguide has an input end near a top of a slider coupled to receive light from an energy source. The waveguide delivers the light at an output end of the waveguide near a bottom of the slider. The apparatus includes light blocking members on respective first and second cross track sides of the waveguide. The light blocking members are configured to block stray light away from a light path. The light blocking members are at a location along a length of the waveguide between the top and the bottom of the slider. Confinement of light within the waveguide is near a maximum at the location.