Heat-assisted recording head having mirror liner that reduces evanescent coupling with near field transducer

A recording head comprising:

• a near-field transducer proximate a media-facing surface of the recording head;
• a waveguide that overlaps and delivers light to the near-field transducer, the light having a near-infrared wavelength;
• and
• a pair of subwavelength focusing mirrors at an end of the waveguide proximate the media-facing surface, the subwavelength focusing mirrors located on opposite crosstrack sides of the near-field transducer, the subwavelength focusing mirrors separated from a peg of the near-field transducer at the media-facing surface by a gap of less than 50 nm, each of the subwavelength focusing mirrors comprising:
• a core comprising a first edge exposed at the media-facing surface, the core formed of a core material that is resistant to mechanical wear and corrosion;
• and
• a liner covering a second edge of the core facing the near-field transducer, the liner comprising a plasmonic metal that is different than the core material and that has at least one of:
• a plasmonic frequency in an ultraviolet range;
• and an extinction coefficient greater than 6.