Polarization rotator for thermally assisted magnetic recording

摘要

A process sequence for forming a waveguide structure with a light polarization rotator section that converts transverse electric light from a TE light source to transverse magnetic light which is subsequently coupled to a plasmon generator (PG) is disclosed. The light polarization rotator section has a length determined by TE LD light wavelength, and the effective mode index of the two orthogonal fundamental modes, and a slope is formed in one side of the symmetric structure with a 45 degree angle with respect to a bottom surface. Offsets that narrow the cross-track width may be formed on the two sides of the light polarization rotator section to improve symmetry for higher TE to TM polarization conversion efficiency.

主权项

1. A method for fabricating a waveguide structure that includes a light polarization rotator section for converting TE light to TM light, comprising:
(a) sequentially depositing a waveguide layer and a hard mask layer on a substrate; (b) patterning the waveguide layer and hard mask layer to give a structure with a lengthwise dimension in a first axis direction that is perpendicular to a cross-track direction, and with a thickness in a down-track direction, and wherein a first section at a first waveguide end has a first width in a cross-track direction, a middle tapered section has a first width at an end that adjoins the first section and a second width less than the first width at a second end, and a third section that is formed between a second end of the waveguide and the second end of the middle tapered section has a second width; (c) etching a middle portion of the third section with ions directed at an angle of about 45 degrees to the substrate such that a portion of the hard mask and waveguide layer along one side of the middle portion are removed and replaced with a sloped side that defines a light polarization rotator section wherein the sloped side connects a top surface with a bottom surface of the middle portion and is formed opposite to a vertical side; and (d) depositing a dielectric layer along the sloped side, vertical side, and on the hard mask layer followed by a chemical mechanical polish process to remove the hard mask and form a top surface of the dielectric layer that is coplanar with a top surface of each of the first section, tapered section, and remaining portions of the third section, and the top surface of the light polarization rotator section.