Semiconductor laser of patterned-substrate type and structure thereof

Claim 2

A semiconductor laser comprising: a patterned-substrate having first and second planar portions in a parallel and spaced relationship and a sloped portion extending between the first and second planar portions; an active layer on the patterned-substrate; a clad layer on the active layer, the clad layer comprising first and second current-blocking regions corresponding, respectively, to the first and second planar portions of the patterned-substrate, and a current channel region corresponding to the sloped portion of the patterned-substrate and extending between the first and second current-blocking regions, the current channel having a thickness tp1 and the current-blocking regions each having a thickness tp2; wherein a thickness ratio R=(tp1/tp2) satisfies the following relationship: R=sin φ{(cos θ/sin θ)+(cos φ/sin φ)} where θ and φ are selected within a range specified by the following condition: tan.sup.-1 (2p1/W)≦θ+φ≦90° where φ is defined as an inclination angle of the current channel region with respect to the first planar portion of the patterned-substrate, and θ is defined as an angle between the growth direction of the clad layer and the first planar portion of the patterned-substrate, and W is defined as the width of the current channel region.

Claim 3

A semiconductor laser as recited in claim 1, wherein the first and second planar portions of the patterned-substrate each have a surface index (100) and the sloped portion of the patterned-substrate extends in the direction <011>.

Claim 4

A semiconductor laser as recited in claim 1, wherein the sloped portion of the patterned-substrate has a surface index (411)A.

Claim 5

A semiconductor laser as recited in claim 1, wherein the active layer is of GaInP.

Claim 6

A semiconductor laser as recited in claim 1, in which the clad layer represents an upper clad layer, the semiconductor laser further comprising a lower clad layer positioned between the active layer and the patterned-substrate.

Claim 7

A semiconductor laser comprising: a patterned-substrate having a planar surface with a mesa-stripe formed on a portion of the planar surface to define an exposed planar surface, the mesa-stripe having a top portion and side surfaces extending from the top portion to the exposed planar surface, each side surface having a first inclination angle with respect to the exposed planar surface; a current blocking layer on the side surfaces of the mesa-stripe and the exposed planar surface of the patterned-substrate, the current blocking layer having sloped portions corresponding to the side surfaces of the mesa-stripe, the sloped portions having a lower surface which defines an interface with the side surfaces of the mesa-stripe and an upper surface which forms a second inclination angle with respect to the exposed planar surface of the patterned-substrate, the second inclination angle being less than the first inclination angle; a plurality of layers formed on the sloped portions of the current-blocking layer and the top portion of the mesa-stripe, the plurality of layers comprising; a buffer layer having a thickness of tp1 on the sloped portion of the current-blocking layer and a thickness tp2 on the top portion of the mesa-stripe, a thickness ratio tp1/tp2 being less than 1, a lower clad layer formed on the buffer layer and having a thickness tp1' on the sloped portion of the current-blocking layer and a thickness tp2' on the top portion of the mesa-stripe, a thickness ratio tp1'/tp2' ranging approximately between 1 and 2, an active layer formed on the lower clad layer, and an upper clad layer formed on the active layer.

Claim 8

A semiconductor laser comprising: a patterned-substrate having a planar surface with a mesa-stripe formed on a portion of the planar surface to define an exposed planar surface, the mesa-stripe having a top portion and side surfaces extending from the top portion to the exposed planar surface, each side surface having a first inclination angle with respect to the exposed planar surface; a current blocking layer on the side surfaces of the mesa-stripe and the exposed planar surface of the patterned-substrate, the current blocking layer having sloped portions corresponding to the side surfaces of the mesa-stripe, the sloped portions having a lower surface which defines an interface with the side surfaces of the mesa-stripe and an upper surface which forms a second inclination angle with respect to the exposed planar surface of the patterned-substrate, the second inclination angle being less than the first inclination angle; a plurality of layers formed on the sloped portions of the current-blocking layer and the top portion of the mesa-stripe, the plurality of layers comprising; a buffer layer having a thickness of tp1 on the sloped portion of the current-blocking layer and a thickness tp2 on the top portion of the mesa-stripe, a thickness ratio tp1/tp2 being less than 1, a lower clad layer formed on the buffer layer and having a thickness tp1' on the sloped portion of the current-blocking layer and a thickness tp2' on the top portion of the mesa-stripe, a thickness ratio tp1'/tp2' ranging approximately between 1 and 2, an active layer formed on the lower clad layer, and an upper clad layer formed on the active layer.