Semiconductor laser element

• US 6,865,202 B2
• Filed: 06/14/2002
• Issued: 03/08/2005
• Est. Priority Date: 06/15/2001
• Status: Expired due to Term

• Current Assignee: Sharp Fukuyama Laser Co., Ltd. (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Matsumoto, Mitsuhiro
• Primary Examiner(s): Harvey, Minsun Oh
• Assistant Examiner(s): Nguyen, Phillip
• Application Number:
  US10/171,513
• Publication Number:
  US 20030016712A1
• Time in Patent Office: 998 Days
• Field of Search: 372 45- 46
• US Class Current: 372/45.01
• CPC Class Codes: H01S 5/2004 Confining in the direction perpendicular to the layer structure
• CPC Class Codes: H01S 5/222 having a refractive index lower than that of the cladding layers or outer guiding layers
• CPC Class Codes: H01S 5/2231 with inner confining structure only between the active layer and the upper electrode

Abstract

There is provided a semiconductor laser element, which has a small capacitance outside a ridge portion and high response speed and is able to effect pulse oscillation with a satisfactory pulse waveform. On a GaAs substrate 101, there are provided an n-type buffer layer 102, an n-type first clad layer 103, an MQW active layer 104, a p-type second clad layer 105, a p-type etching stop layer 106 that has an energy bandgap smaller than that of this second clad layer 105, a p-type third clad layer 107 that constitutes a ridge portion and a p-type protective layer 108. On both sides in the widthwise direction of the ridge portion are laminated a p-type spacer layer 109, an n-type current light confining layer 110, an n-type current confining layer 111 and a p-type flattening layer 112. On these layers is laminated a p-type contact layer 113. A depletion layer spreads into the spacer layer 109 when a bias voltage is applied. Therefore, a capacitance between the spacer layer 109 and the current light confining layer 110 is reduced, and a response speed during the pulse oscillation of the semiconductor laser element becomes fast.

Claims

1. A semiconductor laser element, comprising:

a first conductive type first clad layer,

an active layer,

a second conductive type second clad layer,

a second conductive type etching stop layer that has an energy bandgap smaller than that of the second clad layer,

a ridge-shaped second conductive type third clad layer,

a first conductive type current light confirming layer that is arranged on both sides in a widthwise direction of the third clad layer and has a reflective index smaller then a refractive index of the second clad layer; and

a second conductive type or intrinsic spacer layer arranged in contact with the etching stop layer between the etching stop layer and the current light confining layer.

2. A semiconductor laser element as claimed in claim 1, wherein

the spacer layer has a refractive index equal to or smaller than the reflective index of the second clad layer.

3. A semiconductor laser element as claimed in claim 1, wherein

the spacer layer has a carrier density lower than a carrier density of the second clad layer.

4. A semiconductor laser element as claimed in claim 3, wherein

the carrier density of the spacer layer is not higher than 1×

10¹⁸ cm<sup>−

3</sup>.

5. A semiconductor laser element as claimed in claim 1, wherein an interfacial portion of the current light confining layer, which is in contact with the spacer layer, has a carrier density lower than the remainder of the current light confining layer.

6. A semiconductor laser element as claimed in claim 5, wherein the carrier density of the interfacial portion of the current light confining layer in contact with the spacer layer is not higher than 1×

10¹⁸ cm<sup>−

3</sup>.

7. A semiconductor laser element as claimed in claim 1, wherein

the spacer layer has a thickness of not smaller than 0.05 μ

m and not greater than 0.5 μ

m.

8. A semiconductor laser element as claimed in claim 7, wherein

the spacer layer has a thickness of not smaller than 0.1 μ

m and not greater than 0.3 μ

m.

9. A semiconductor laser element as claimed in claim 5, wherein the interfacial portion of the current light confining layer in contact with the spacer layer has a thickness of not smaller than 0.5 μ

m and not greater than 0.5 μ

m.

10. A semiconductor laser element as claimed in claim 1, wherein the spacer layer is doped with an impurity than contains carbon.

11. A semiconductor laser element as claimed in claim 1, wherein the etching stop layer in contact with the spacer layer is doped with an impurity that contains carbon.

12. A semiconductor laser element as claimed in claim 1, wherein the second clad layer is doped with an impurity that contains carbon at least on the spacer layer side.

13. A semiconductor laser element as claimed in claim 12, wherein the second clad layer is doped with an impurity other than carbon in its portion that is in contact with the active layer.

14. A semiconductor laser element as claimed in claim 1, wherein the second clad layer has a portion in contact with the active layer that has a carrier density higher than a carrier density of its portion in contact with the spacer layer.

15. A semiconductor laser element as claimed in claim 1, wherein the current light confining layer is doped with an impurity that contains silicon.