Surface emitting laser element array

• US 7,974,327 B2
• Filed: 09/01/2006
• Issued: 07/05/2011
• Est. Priority Date: 03/14/2006
• Status: Active Grant

• Current Assignee: Furukawa Electric Company Limited
• Original Assignee: Furukawa Electric Company Limited
• Inventors: Nishikata, Kazuaki, Iwai, Norihiro, Kageyama, Takeo, Ariga, Maiko
• Primary Examiner(s): Harvey; Minsun
• Assistant Examiner(s): Carter; Michael
• Application Number:
  US12/224,719
• Publication Number:
  US 20100195689A1
• Time in Patent Office: 1,768 Days
• Field of Search: 372/50.12, 372/50.124, 372/46.01
• US Class Current: 372/50.124
• CPC Class Codes: H01L 2224/48091 Arched
• CPC Class Codes: H01L 2224/49175 Parallel arrangements
• CPC Class Codes: H01L 2924/00014 the subject-matter covered by the group, the symbol of which is combined with the symbol of this group, being disclosed without further technical details
• CPC Class Codes: H01S 2301/176 Specific passivation layers on surfaces other than the emission facet
• CPC Class Codes: H01S 2301/18 Semiconductor lasers with special structural design for influencing the near- or far-field
• CPC Class Codes: H01S 5/02345 Wire-bonding
• CPC Class Codes: H01S 5/0422 with n- and p-contacts on the same side of the active layer
• CPC Class Codes: H01S 5/04257 having positive and negative electrodes on the same side of the substrate
• CPC Class Codes: H01S 5/06226 Modulation at ultra-high frequencies
• CPC Class Codes: H01S 5/18313 by oxidizing at least one of the DBR layers
• CPC Class Codes: H01S 5/18341 Intra-cavity contacts
• CPC Class Codes: H01S 5/423 having a vertical cavity

Abstract

A surface emitting laser element array comprises a plurality of surface emitting laser elements (15) on a same substrate (1) each comprising a mesa post formed of a laminated structure including an active layer (4) for reducing a crosstalk between the surface emitting laser elements constituting the surface emitting laser element array, and for improving a high speed response, wherein each of the surface emitting laser elements (15) comprises a first electrode (9), a second electrode (10) and a third electrode (11) that have a polarity different from that of the first electrode (9); the first electrode (9) is arranged on the mesa post; the second electrode (10) is arranged on one surface of the substrate (1) same as that of the first electrode (9); the third electrode (11) is arranged on the other surface of the substrate (1) opposite to that of the first electrode and the second electrode (9, 10) and is provided as a common electrode of the surface emitting laser elements (15); and an electric current is applied to the active layer (4) using the first electrode (9) and the second electrode (10).

Claims

1. A surface emitting laser element array comprising:

a plurality of surface emitting laser elements formed in an array pattern on a top surface of a substrate, wherein

each of the surface emitting laser elements includes

a lower DBR mirror formed on the substrate,

a lower cladding layer formed on the lower DBR mirror,

an active layer formed on the lower cladding layer,

an upper cladding layer formed on the active layer,

an upper DBR mirror,

a mesa post formed of a layered structure including at least the active layer, the upper cladding layer, and the upper DBR mirror,

a first electrode formed on a first side of the substrate,

a second electrode formed on the first side of the substrate, the second electrode having a polarity opposite to that of the first electrode, and

a third electrode formed on a second side of the substrate opposite to the first side of the substrate, the third electrode having a polarity the same as that of the second electrode,

the third electrode is a common electrode for the surface emitting laser elements,

an electric current is applied to the active layer through the first electrode and the second electrode,

the lower DBR mirror includes

a semi-insulating first lower DBR mirror formed on the substrate, and

an electrically-conductive second lower DBR mirror formed on the first lower DBR mirror, and

the second electrode is electrically connected to the third electrode.

2. The surface emitting laser element array according to claim 1, wherein the second electrode is electrically connected to the third electrode via a ground.

3. The surface emitting laser element array according to claim 1, wherein the first electrode is formed on the upper DBR mirror, the second electrode is formed on the second lower DBR mirror, and the third electrode is formed on a bottom surface of the substrate.

4. The surface emitting laser element array according to claim 1, wherein the first electrode is formed on the upper DBR mirror, the layered structure forming the mesa post further includes the lower cladding layer, the second electrode is formed on the lower cladding layer, and the third electrode is formed on a bottom surface of the substrate.

5. The surface emitting laser element array according to claim 3, wherein each of the surface emitting laser elements further includes a current blocking layer provided in any one of the lower cladding layer, the upper cladding layer, the lower DBR mirror, and the upper DBR mirror, and a current equalizer layer provided at a region near the current blocking layer for equalizing a current distribution in an opening formed by the current blocking layer.

6. The surface emitting laser element array according to claim 5, wherein the current blocking layer is provided in either one of the upper cladding layer and the upper DBR mirror in the mesa post.

7. The surface emitting laser element array according to claim 5, wherein either one of the lower DBR mirror and the upper DBR mirror is formed of a p-type semiconductor, and said current equalizer layer is provided in either one of the lower DBR mirror and the upper DBR mirror on a side of the current blocking layer opposite to the active layer.

8. The surface emitting laser element array according to claim 7, wherein the p-type semiconductor includes a semiconductor formed in a layered structure as represented with p-Al_xGa_1-xAs/p-Al_yGa_1-yAs (0≦

x≦

1, 0≦

y≦

1).

9. The surface emitting laser element array according to claim 5, wherein the current equalizer layer has an electrical resistivity lower than that of a layer constituting at least one of the lower DBR mirror and the upper DBR mirror.

10. The surface emitting laser element array according to claim 5, wherein said current equalizer layer has an electrical resistivity higher than that of a layer constituting at least one of the lower DBR mirror and the upper DBR mirror.

11. The surface emitting laser element array according to claim 5, wherein the current equalizer layer is formed of a layered structure including a low electrical resistivity layer having an electrical resistivity lower than that of a layer constituting at least one of the lower DBR mirror and the upper DBR mirror, and a high electrical resistivity layer having an electrical resistivity higher than, that of the layer and is arranged as a layer between the current blocking layer and the low electrical resistivity layer.

12. The surface emitting laser element array according to claim 5, wherein the current equalizer layer is formed of one layer constituting the lower DBR mirror or the upper DBR mirror, or an interface of the one layer with an impurity of not less than 5×

10¹⁸ cm<sup>−

3</sup> doped therein.

13. The surface emitting laser element array according to claim 4, wherein each of the surface emitting laser elements further includes a current blocking layer provided in any one of the lower cladding layer, the upper cladding layer, the lower DBR mirror, and the upper DBR mirror, and a current equalizer layer provided at a region near the current blocking layer for equalizing a current distribution in an opening formed by the current blocking layer.

14. The surface emitting laser element array according to claim 13, wherein the current blocking layer is provided in either one of the upper cladding layer and the upper DBR mirror in the mesa post.

15. The surface emitting laser element array according to claim 13, wherein either one of the lower DBR mirror and the upper DBR mirror is formed of a p-type semiconductor, and the current equalizer layer is provided in either one of the lower DBR mirror and the upper DBR mirror on a side of the current blocking layer opposite to the active layer.

16. The surface emitting laser element array according to claim 15, wherein the p-type semiconductor includes a semiconductor formed in a layered structure represented by p-AlxGa1-xAs/p-AlyGa1-yAs (0≦

x≦

1, 0≦

y≦

1).

17. The surface emitting laser element array according to claim 13, wherein the current equalizer layer has an electrical resistivity lower than that of a layer constituting at least one of the lower DBR mirror and the upper DBR mirror.

18. The surface emitting laser element array according to claim 13, wherein the current equalizer layer has an electrical resistivity higher than that of a layer constituting at least one of the lower DBR mirror and the upper DBR mirror.

19. The surface emitting laser element array according to claim 13, wherein the current equalizer layer is formed of a layered structure including a low electrical resistivity layer having an electrical resistivity lower than that of a layer constituting at least one of the lower DBR mirror and the upper DBR mirror and a high electrical resistivity layer having an electrical resistivity higher than that of the layer and is arranged as a layer between the current blocking layer and the low electrical resistivity layer.

20. The surface emitting laser element array according to claim 13, wherein the current equalizer layer is formed of one layer constituting the lower DBR mirror or the upper DBR mirror, or an interface of the one layer with an impurity of not less than 5×

10¹⁸ cm<sup>−

3</sup> doped therein.