Patent ID: 8089830

Claim:
A near-field light generating device comprising: a waveguide that allows light to propagate therethrough and has a top surface and a groove, the groove opening in the top surface and extending in a first direction parallel to the top surface; a clad layer having a bottom surface in contact with the top surface of the waveguide, a top surface opposite to the bottom surface, and an opening that penetrates from the top surface to the bottom surface and is contiguous to the groove; a near-field light generating element that extends in the first direction, at least part of the near-field light generating element being accommodated in the opening; and a buffer layer that is interposed between the near-field light generating element and each of the waveguide and the clad layer in the groove and the opening, wherein: each of the clad layer and the buffer layer has a refractive index lower than that of the waveguide; the opening has a first opening sidewall and a second opening sidewall that decrease in distance from each other toward the top surface of the waveguide; the groove has a first groove sidewall that is contiguous to the first opening sidewall, and a second groove sidewall that is contiguous to the second opening sidewall; an angle that the first groove sidewall forms with respect to a second direction perpendicular to the top surface of the waveguide is smaller than an angle that the first opening sidewall forms with respect to the second direction; an angle that the second groove sidewall forms with respect to the second direction is smaller than an angle that the second opening sidewall forms with respect to the second direction; the near-field light generating element includes: a first side surface and a second side surface that are respectively opposed to the first and second opening sidewalls with the buffer layer therebetween, and decrease in distance from each other toward the groove; an edge part that connects the first and second side surfaces to each other and is opposed to the groove with the buffer layer therebetween; and a near-field light generating part that lies at one end of the edge part and generates near-field light; the light propagating through the waveguide is totally reflected at an interface between the waveguide and the buffer layer, and evanescent light thereby occurs from the interface; and a surface plasmon is excited on the edge part through coupling with the evanescent light, the surface plasmon propagates along the edge part to the near-field light generating part, and the near-field light generating part generates the near-field light based on the surface plasmon.