Heat-assisted magnetic recording head including plasmon generator

A heat-assisted magnetic recording head comprising:

• a medium facing surface that faces a magnetic recording medium;
• a magnetic pole that has an end face located in the medium facing surface and produces a write magnetic field for writing data on the magnetic recording medium;
• a waveguide including a core and a clad, the core propagating light;
• a plasmon generator having a near-field light generating part located in the medium facing surface;
• and
• a dielectric layer that has a refractive index lower than that of the core, wherein:
• the core has an evanescent light generating surface that generates evanescent light based on the light propagated through the core;
• the plasmon generator has an outer surface;
• the outer surface of the plasmon generator includes a plasmon exciting surface and a plasmon propagating surface that face toward opposite directions, the plasmon exciting surface being substantially in contact with the evanescent light generating surface, the plasmon propagating surface being in contact with the dielectric layer;
• the plasmon exciting surface includes a first width changing portion;
• the plasmon propagating surface includes a second width changing portion;
• each of the first and second width changing portions has a width that decreases with decreasing distance to the medium facing surface, the width being in a direction parallel to the medium facing surface and the evanescent light generating surface;
• the second width changing portion has two sides that lie on opposite sides in the direction of the width;
• each of the two sides forms an angle in the range of 3 to 50 degrees with respect to a direction perpendicular to the medium facing surface;
• a surface plasmon is excited on the plasmon exciting surface through coupling with the evanescent light generated from the evanescent light generating surface, the surface plasmon moves from the plasmon exciting surface to the plasmon propagating surface in the first and second width changing portions, and is further propagated along the plasmon propagating surface to the near-field light generating part, and the near-field light generating part generates near-field light based on the surface plasmon.