Assistant waveguides for evaluating main waveguide coupling efficiency and diode laser alignment tolerances for hard disk

A method for aligning a light source to a target waveguide in a heat assisted magnetic recording (HAMR) transducer on a slider, the HAMR transducer comprising a first and second opposing surfaces, wherein the first surface is aligned to an air bearing surface (ABS) of the slider and the second surface is aligned to a surface of the slider opposite the ABS, the method comprising:

• aligning an entrance of the target waveguide on the second surface of the HAMR transducer to the light source to direct light toward the first surface of the HAMR transducer, wherein the target waveguide expands in cross-section area with distance from the entrance to form an inverse taper waveguide;
• monitoring energy received at a plurality of output devices from a plurality of assistant waveguides in the HAMR transducer, each of the plurality of assistant waveguides having an entrance at the second surface of the HAMR transducer to receive portions of the light directly from the light source;
• and
• adjusting the alignment on the basis of the energy monitored at the output devices.