Systems and methods for controlling light phase difference in interferometric waveguides at near field transducers

A method of manufacturing a system for controlling light phase at a near field transducer (NFT) of an interferometric waveguide, the method comprising:

• forming a splitter on a slider, the splitter configured to receive light from a laser and to split the light into a first waveguide arm and a second waveguide arm, the first waveguide arm and the second waveguide arm converging at a junction opposite the splitter in a light propagating direction, wherein the first waveguide arm is longer than the second waveguide arm by a preselected distance;
• forming the near field transducer (NFT) on the slider and proximate the junction, the NFT configured to receive the light;
• attaching the laser to a submount;
• attaching a heater to the submount proximate the laser, the heater configured to heat the laser and thereby generate and maintain a preselected phase difference in the light arriving at the NFT;
• and
• attaching the submount to the slider such that the splitter is substantially aligned to receive the light from the laser.