Semiconductor laser device having a lens-like refractive index distribution within the stripe

Claim 2

In a semiconductor laser device wherein a first clad layer made of a semiconductor having a first conductivity type, an active layer, and a second clad layer made of a semiconductor having a second conductivity type opposite to said first conductivity type are disposed on a substrate; the improvement comprising lens-like portions which exhibit a refractive index distribution having a lens effect of magnifying light formed in a stripe of said laser device and in at least one of said active layer and a part of one or both of said first and second clad layers into which light leaks from said active layer wherein said lens-like portions are shaped to be convex when a refractive index in said lens-like portions is lower than a refractive index of the layer in which the lens-like portions are formed, and said lens-like portions are shaped to be concave when a refractive index in said lens-like portions is higher than a refractive index of the layer in which the lens-like portions are formed.

Claim 3

In a semiconductor laser device wherein a first clad layer made of a semiconductor having a first conductivity type, an active layer, and a second clad layer made of a semiconductor having a second conductivity type opposite to said first conductivity type are disposed on a substrate; the improvement comprising lens-like portions which exhibit a refractive index distribution having a lens effect of magnifying light formed in a stripe of said laser device and in at least one of said active layer and a part of one or both of said first and second clad layers into which light leaks from said active layer wherein said lens-like portions are shaped to be convex when a refractive index in said lens-like portions is lower than a refractive index of the layer in which the lens-like portions are formed, and said lens-like portions are shaped to be concave when a refractive index in said lens-like portions is higher than a refractive index of the layer in which the lens-like portions are formed, and further wherein a radius of curvature R of each lens-like portion and a pitch d of said lens-like portions satisfy the following inequality: ##EQU5## wherein n 1 denotes an effective refractive index inside said lens-like portions and n 2 denotes an effective refractive index outside said lens-like portions in the layer in which said lens-like portions are formed, k 1 denotes an effective refractive index at an apex of a self-focusing region having a parabolic distribution, and k 2 denotes a coefficient in a square term of an equation indicative of the parabolic distribution.

Claim 4

In a semiconductor laser device wherein a first clad layer made of a semiconductor having a first conductivity type, an active layer, and a second clad layer made of a semiconductor having a second conductivity type opposite to said first conductivity type are disposed on a substrate; the improvement comprising lens-like portions which exhibit a refractive index distribution having a lens effect of magnifying light formed in a stripe of said laser device and in at least one of said active layer and a part of one or both of said first and second clad layers into which light leaks from said active layer wherein said lens-like portions are shaped to be convex when a refractive index in said lens-like portions is lower than a refractive index of the layer in which the lens-like portions are formed, and said lens-like portions are shaped to be concave when a refractive index in said lens-like portions is higher than a refractive index of the layer in which the lens-like portions are formed, and further wherein a radius of curvature R of each lens-like portion and a pitch d of said lens-like portions satisfy the following inequality: ##EQU5## wherein n 1 denotes an effective refractive index inside said lens-like portions and n 2 denotes an effective refractive index outside said lens-like portions in the layer in which said lens-like portions are formed, k 1 denotes an effective refractive index at an apex of a self-focusing region having a parabolic distribution, and k 2 denotes a coefficient in a square term of an equation indicative of the parabolic distribution.

Claim 5

A semiconductor laser device as defined in claim 2, wherein said active layer and said clad layers are made of a GaAs system compound including Ga x Al 1-x As, and values of each of the effective refractive indices n 1 , n 2 and k 1 are about 3.4, while a value of the coefficient k 2 is about 4×10 -5 .

Claim 6

A semiconductor laser device as defined in claim 3, wherein an absolute value of an index difference (n 2 -n 1 ) is 5×10 -3 -2×10 -2 .

Claim 7

A semiconductor laser device as defined in claim 1, further comprising another lens-like portion which exhibits a refractive index distribution having a lens effect of condensing light, said another lens-like portion being formed in said active layer at an end face of said stripe, the end face serving as an emission port for a laser beam of said laser device.

Claim 8

A semiconductor laser device having a stripe, a resonant cavity and a pumping means wherein a first clad layer made of a semiconductor having a first conductivity type, an active layer, and a second clad layer made of a semiconductor having a second conductivity type opposite to said first conductivity type are disposed on a substrate; lens-like portions which exhibit a refractive index distribution having a lens effect of magnifying light formed in a stripe of said laser device and in at least one of said active layer and a part of one or both of said first and second clad layers into which light leaks from said active layer wherein said lens-like portions are shaped to be convex when a refractive index in said lens-like portions is lower than a refractive index of the layer in which the lens-like portions are formed, and said lens-like portions are shaped to be concave when a refractive index in said lens-like portions is higher than a refractive index of the layer in which the lens-like portions are formed.

Claim 9

A semiconductor laser device having a stripe, a resonant cavity and a pumping means wherein a first clad layer made of a semiconductor having a first conductivity type, an active layer, and a second clad layer made of a semiconductor having a second conductivity type opposite to said first conductivity type are disposed on a substrate; lens-like portions which exhibit a refractive index distribution having a lens effect of magnifying light formed in a stripe of said laser device and in at least one of said active layer and a part of one or both of said first and second clad layers into which light leaks from said active layer wherein said lens-like portions are shaped to be convex when a refractive index in said lens-like portions is lower than a refractive index of the layer in which the lens-like portions are formed, and said lens-like portions are shaped to be concave when a refractive index in said lens-like portions is higher than a refractive index of the layer in which the lens-like portions are formed.

Claim 10

In a semiconductor laser device having a stripe wherein a first clad layer made of a semiconductor having a first conductivity type, an active layer, and a second clad layer made of a semiconductor having a second conductivity type opposite to said first conductivity type are disposed on a substrate; a waveguide structure including lens-like portions which exhibit a refractive index distribution having a lens effect of magnifying light formed in a stripe of said laser device and in at least one of said active layer and a part of one or both of said first and second clad layers into which light leaks from said active layer wherein said lens-like portions are shaped to be convex when a refractive index in said lens-like portions is lower than a refractive index of the layer in which the lens-like portions are formed, and said lens-like portions are shaped to be concave when a refractive index in said lens-like portions is higher than a refractive index of the layer in which the lens-like portions are formed.

Claim 11

In a semiconductor laser device having a stripe wherein a first clad layer made of a semiconductor having a first conductivity type, an active layer, and a second clad layer made of a semiconductor having a second conductivity type opposite to said first conductivity type are disposed on a substrate; a waveguide structure including lens-like portions which exhibit a refractive index distribution having a lens effect of magnifying light formed in a stripe of said laser device and in at least one of said active layer and a part of one or both of said first and second clad layers into which light leaks from said active layer wherein said lens-like portions are shaped to be convex when a refractive index in said lens-like portions is lower than a refractive index of the layer in which the lens-like portions are formed, and said lens-like portions are shaped to be concave when a refractive index in said lens-like portions is higher than a refractive index of the layer in which the lens-like portions are formed.

Claim 12

In a semiconductor laser device including: a semiconductor substrate; a first clad layer formed on said substrate; an active layer formed on said first clad layer; a second clad layer formed on said active layer; a light absorbing layer formed on said second clad layer, and being shaped into a stripe formation; the improvement comprising; lens-like portions formed in at least one of said layers exposed below said light absorbing layer; a third clad layer formed on said light absorbing layer and said lens-like portions, so as to be buried in said lens-like portions; and a cap layer formed on said third clad layer.

Claim 13

In a semiconductor laser device including: a semiconductor substrate; a first clad layer formed on said substrate; an active layer formed on said first clad layer; a second clad layer formed on said active layer; a light absorbing layer formed on said second clad layer, and being shaped into a stripe formation; the improvement comprising; lens-like portions formed in at least one of said layers exposed below said light absorbing layer; a third clad layer formed on said light absorbing layer and said lens-like portions, so as to be buried in said lens-like portions; and a cap layer formed on said third clad layer.

Claim 14

A semiconductor laser device according to claim 8, further including a semiconductor layer formed between said second clad layer and said light absorbing layer.

Claim 15

A semiconductor laser device according to claim 8, wherein said lens-like portions are formed in at least said semiconductor layer.

Claim 16

A semiconductor laser device according to claim 8, wherein said lens-like portions are formed in at least said second clad layer.

Claim 17

A semiconductor laser device according to claim 8, wherein said lens-like portions extend in a two-dimensional array.

Claim 18

A semiconductor laser device according to claim 8, wherein said lens-like portions are formed in at least said second clad layer and said active layer.

Claim 19

A semiconductor laser device according to claim 8, further including a quantum well structure formed on said second clad layer; a semiconductor layer formed on said quantum well structure in which said lens-like portions are formed; and a zinc doped layer formed on said light absorbing layer and buried in said lens-like portions, for diffusing zinc into said quantum well structure.

Claim 20

A semiconductor laser device according to claim 13, wherein a stripe of said laser device has a width of 10-40 μm.

Claim 21

A semiconductor laser device according to claim 8, further including another lens-like portion formed in at least said second clad layer at the end face of a stripe of said laser device.

Claim 22

A semiconductor laser device according to claim 16, wherein said end face is positioned to be opposite to a reflective surface of said laser device.

Claim 23

A semiconductor laser device according to claim 8, wherein said laser device includes a plurality of stripes each having an end face positioned to be opposite to monitoring photodiodes of said laser device, and further lens-like portions formed in at least said second clad layer at said end face of each stripe.

Claim 24

A semiconductor laser device according to claim 8, wherein said laser device includes a plurality of laser cavities coupled together.