Buried-heterostructure diode injection laser

A heterojunction diode laser for producing a substantially symmetrically output light beam comprising:

• a substrate body of a semiconductor material having a surface with an elongated groove formed in said surface,
• a first layer of a semiconductor material in integral contact with said surface of said substrate, said first layer having a substantially planar portion on each side of said groove and a portion within said groove with a surface of said portion within said groove inwardly arched toward said substrate body,
• a second layer of a semiconductor material in integral contact with said first layer, said second layer having a central portion substantially within said groove and substantially planar portions on each side of said central portion, said central portion having a surface conforming to the shape of said inwardly arched surface of said first layer and a substantially flat surface adjacent said inwardly arched surface,
• a third layer of semiconductor material in integral contact with said second layer,
• said material of said second layer having an index of refraction greater than the index of refraction of both the material of said first layer and the material of said third layer to thereby provide a heterogeneous laser, at least two of said first, second and third layers being of a different conductivity type such that a rectifying junction exists between two of said first, second and third layers, and
• means located on both sides of said groove formed in said surface of said substrate for restricting the flow of pump current to a path through said central portion of said layer when said rectifying junction is forward biased to thereby achieve population inversion in said central portion of said second layer such that light is produced by radiative recombination of the carriers in said central portion of said second layer with the light being guided by said first and third layers due to the lower index of refraction of the materials of said first and third layers relative to the material of said second layer.

A heterojunction diode laser comprising:

• a substrate body having a surface with an elongated groove formed in said surface,
• a first layer of a first material deposited on said surface, said first layer having a surface configuration remote from said surface of said substrate with a portion which is concave toward said substrate within a substantial portion of said groove,
• a second layer of a second material deposited on said first layer, said second material having an index of refraction greater than said first material, said second layer having substantially planar portions on both sides of said groove and a substantially bowl-shaped portion substantially within said groove and in contact with said concave portion of said surface of said first layer remote from said substrate,
• a third layer of a third material deposited on said second layer, said third material having a lower index of refraction than said second material,
• at least two of said first, second and third layers being of a different conductivity type such that a rectifying junction exists between two of said first, second and third layers, and
• means located on both sides of said groove formed in said surface of said substrate for restricting the flow of pump current to a path through said groove and through said bowl-shaped portion of said second layer when said rectifying junction is forward biased to thereby achieve population inversion in said bowl-shaped portion of said second layer such that light is produced by radiative recombination of the carriers in said bowl-shaped portion of said second layer with the light being guided by said first and third layers due to the lower index of refraction of said materials of said first and third layers relative to said material of said second layer.