Method for compensating for phase variations in an interferometric tapered waveguide in a heat assisted magnetic recording head

A method for providing an interferometric tapered waveguide (ITWG) for a heat-assisted magnetic recording (HAMR) transducer comprising:

• defining the ITWG from at least one waveguide layer, the at least one waveguide layer including an energy sensitive core layer, the energy sensitive core layer having an index of refraction that varies in response to exposure to energy having a particular wavelength range, the step of defining the ITWG including defining a plurality of arms for the ITWG;
• determining at least one phase difference between the plurality of arms;
• and
• exposing at least one of the plurality of arms to the energy after the determining step such that the index of refraction of the energy sensitive core layer in the at least one of the plurality of arms is changed and such that the at least one phase difference between the plurality of arms is changed to at least one new phase difference, the at least one new phase difference being substantially constant during operation of the HAMR transducer and in-operation of the HAMR transducer;
• wherein the plurality of arms have a target phase difference, the target phase difference corresponding to a target optical length for one of the plurality of arms, and wherein the step of defining the ITWG further includes:
• defining the one of the plurality of arms to have an optical length greater than the target optical length such that the at least one phase difference is greater than the target phase difference;
• and
• wherein the index of refraction of the energy sensitive core layer is reduced by exposure to the energy.

A method for providing an interferometric tapered waveguide (ITWG) for a heat-assisted magnetic recording (HAMR) transducer comprising:

• defining the ITWG from at least one waveguide layer, the at least one waveguide layer including an enemy sensitive core layer, the energy sensitive core layer having an index of refraction that varies in response to exposure to energy having a particular wavelength range, the step of defining the ITWG including defining a plurality of arms for the ITWG;
• determining at least one phase difference between the plurality of arms;
• and
• exposing at least one of the plurality of arms to the enemy after the determining step such that the index of refraction of the energy sensitive core layer in the at least one of the plurality of arms is changed and such that the at least one phase difference between the plurality of arms is changed to at least one new phase difference, the at least one new phase difference being substantially constant during operation of the HAMR transducer and in-operation of the HAMR transducer;
• wherein the plurality of arms have a target phase difference, the target phase difference corresponding to a target optical length for one of the plurality of arms, and wherein the step of defining the ITWG further includes:
• defining the one of the plurality of arms to have an optical length less than the target optical length such that the at least one phase difference is less than the target phase difference;
• and
• wherein the index of refraction of the energy sensitive core layer is increased by exposure to the energy.

A method for providing an interferometric tapered waveguide (ITWG) for an energy-assisted magnetic recording (HAMR) transducer, the method comprising:

• providing a bottom cladding layer;
• providing an energy sensitive core layer on the bottom cladding layer, the energy sensitive core layer having an index of refraction that decreases in response to exposure to energy having a particular wavelength range;
• providing a top cladding layer on the energy sensitive core layer;
• defining the ITWG including defining a plurality of arms for the ITWG, the ITWG having a target phase difference, the target phase difference corresponding to a target optical length for an arm of the plurality of arms, the arm of the plurality of arms having a longer optical length greater than the optical length such that the phase difference is greater than the target phase difference;
• providing a mask on the plurality of arms, the mask being opaque to the energy and including an aperture therein, the aperture exposing a portion of the arm, covering a remaining portion of the arm, and covering any remaining arms of the plurality of arms;
• determining at least one phase difference between the arm and the any remaining arms;
• and
• exposing the portion of the arm to the energy after the determining step such that the index of refraction of the energy sensitive core layer in the portion of the arm is reduced and such that the least one phase difference between the arm and the any remaining arms is changed to at least one new phase difference, the at least one new phase difference being substantially constant during operation of the HAMR transducer and in-operation of the HAMR transducer.