Semiconductor laser having a non-absorbing passive region with beam guiding

Claim 2

A semiconductor laser comprising: a body of material having a pair of opposed end faces which are reflective of light, at least one of which is partially transmissive of light to form a laser cavity having an optical axis extending between the end faces, said body including: a substrate having first and second opposed major surfaces; a first cladding region overlying said first major surface; a guide layer overlying the first cladding region and tapering in increasing thickness in the lateral direction from the optical axis; an active layer which tapers in decreasing thickness from the optical axis overlying a portion of the guide layer and spaced a distance from a first end face; a second cladding region overlying the active layer; a non-absorbing mode control layer which tapers in decreasing thickness in the lateral direction from the optical axis overlying the guide layer and extending between the active layer and said first end face; a burying region overlying the mode control layer; and first and second electrical contacts overlying said second cladding region and said second major surface respectively.

Claim 3

The laser of claim 1 wherein the active layer has a larger refractive index than the guide layer and the guide layer has a larger refractive index than the first and second cladding regions and the burying region.

Claim 4

The laser of claim 2 wherein the refractive index of the mode control layer is different from that of the guide layer.

Claim 5

The laser of claim 3 wherein the refractive index of the mode control layer is less than that of the guide layer.

Claim 6

The laser of claim 3 wherein the refractive index of the mode control layer is greater than that of the guide layer.

Claim 7

The laser of claim 3 wherein a cap layer overlies the second cladding region and an electrically insulating layer having an opening therethrough, overlies the cap layer and the burying region and the first electrical contact overlies the electrically insulating layer and the cap layer in said opening.

Claim 8

The laser of claim 6 wherein the substrate and the cap layer are composed of GaAs, the first and second cladding regions, the guide and mode control layers and the burying region are composed of AlGaAs alloys.

Claim 9

The laser of claim 1 wherein the active layer is spaced a distance from both of the end faces and the mode control layer extends between the active layer and both end faces.

Claim 10

The laser of claim 1 wherein the mode control layer is thicker than the active layer along the optical axis.

Claim 11

A semiconductor laser comprising: a body of material having a pair of opposed end faces which are reflective of light, at least one of which is partially transmissive of light to form a laser cavity having an optical axis extending between the end faces, said body including: a substrate having first and second opposed major surfaces and having a pair of substantially parallel channels extending between the end faces with a mesa therebetween in the first surface; a first cladding region overlying said first major surface, the channels and the mesa; a guide layer overlying the first cladding region and tapering in increasing thickness in the lateral direction from the optical axis; an active layer which tapers in decreasing thickness from the optical axis overlying a portion of the guide layer and spaced a distance from a first end face; a second cladding region overlying the active layer; a mode control layer which tapers in decreasing thickness in the lateral direction from the optical axis overlying the guide layer and extending between the active layer and said first end face; a burying region overlying the mode control layer; and first and second electrical contacts overlying said second cladding region and said second major surface respectively.

Claim 12

A semiconductor laser comprising: a body of material having a pair of opposed end faces which are reflective of light, at least one of which is partially transmissive of light to form a laser cavity having an optical axis extending between the end faces, said body including: a substrate having first and second opposed major surfaces and having a pair of substantially parallel channels extending between the end faces with a mesa therebetween in the first surface; a first cladding region overlying said first major surface, the channels and the mesa; a guide layer overlying the first cladding region and tapering in increasing thickness in the lateral direction from the optical axis; an active layer which tapers in decreasing thickness from the optical axis overlying a portion of the guide layer and spaced a distance from a first end face; a second cladding region overlying the active layer; a mode control layer which tapers in decreasing thickness in the lateral direction from the optical axis overlying the guide layer and extending between the active layer and said first end face; a burying region overlying the mode control layer; and first and second electrical contacts overlying said second cladding region and said second major surface respectively.

Claim 13

The laser of claim 10 wherein the optical axis is over the center of the mesa.

Claim 14

The laser of claim 11 wherein the active layer has a larger refractive index than the guide layer and the guide layer has a larger refractive index than the first and second cladding regions and the burying region.

Claim 15

The laser of claim 12 wherein the refractive index of the mode control layer is different from that of the guide layer.

Claim 16

The laser of claim 13 wherein the refractive index of the mode control layer is less than that of the guide layer.

Claim 17

The laser of claim 13 wherein the refractive index of the mode control layer is greater than that of the guide layer.

Claim 18

The laser of claim 13 wherein a cap layer overlies the second cladding region and an electrically insulating layer having an opening therethrough, overlies the cap layer and the burying region and the first electrical contact overlies the electrically insulating layer and the cap layer in said opening.

Claim 19

The laser of claim 16 wherein the substrate and the cap layer are composed of GaAs, the first and second cladding regions, the guide and mode control layers and the burying region are composed of AlGaAs alloys.

Claim 20

The laser of claim 11 wherein the active layer is spaced a distance from both of the end faces and the mode control layer extends between the active layer and both end faces.

Claim 21

The laser of claim 10 wherein the mode control layer is thicker than the active layer along the optical axis.

Claim 22

A semiconductor laser comprising: a body of material having a pair of opposed end faces which are reflective of light, at least one of which is partially transmissive of light to form a laser cavity having an optical axis extending between the end faces, said body including: a substrate having first and second opposed major surfaces; a first cladding region overlying said first major surface; a guide layer overlying the first cladding region; an active layer overlying a portion of the guide layer and spaced a distance from a first end face; a second cladding region overlying the active layer; a mode control layer, which is nonabsorbing at wavelength of the emitted laser light, overlying the guide layer and extending between the active layer and said first end face; a burying region overlying the mode control layer; and first and second electrical contacts overlying said second cladding region and said second major surface respectively wherein the active layer has a larger refractive index than the guide layer and the guide layer has a larger refractive index than the first and second cladding regions and the burying region; and wherein the refractive index of the mode control layer is different from that of the guide layer and is larger than the refractive indices of the cladding regions and the burying region.

Claim 23

A semiconductor laser comprising: a body of material having a pair of opposed end faces which are reflective of light, at least one of which is partially transmissive of light to form a laser cavity having an optical axis extending between the end faces, said body including: a substrate having first and second opposed major surfaces; a first cladding region overlying said first major surface; a guide layer overlying the first cladding region; an active layer overlying a portion of the guide layer and spaced a distance from a first end face; a second cladding region overlying the active layer; a mode control layer, which is nonabsorbing at wavelength of the emitted laser light, overlying the guide layer and extending between the active layer and said first end face; a burying region overlying the mode control layer; and first and second electrical contacts overlying said second cladding region and said second major surface respectively wherein the active layer has a larger refractive index than the guide layer and the guide layer has a larger refractive index than the first and second cladding regions and the burying region; and wherein the refractive index of the mode control layer is different from that of the guide layer and is larger than the refractive indices of the cladding regions and the burying region.

Claim 24

The laser of claim 20 wherein the refractive index of the mode control layer is less than that of the guide layer.

Claim 25

The laser of claim 21 wherein the first and second cladding regions, the guide and mode control layers and the burying region are composed of AlGaAs alloys with the aluminum concentration in the mode control layer being greater than the aluminum concentration in the guide layer.

Claim 26

The laser of claim 20 wherein the refractive index of the mode control layer is greater than that of the guide layer.

Claim 27

The laser of claim 23 wherein the first and second cladding regions, the guide and mode control layers and the burying regions are composed of AlGaAs alloys with the aluminum concentration in the mode control layer being less than the aluminum concentration in the guide layer.