Surface light emitting type semiconductor laser having a vertical cavity

• US 6,856,635 B2
• Filed: 10/22/2002
• Issued: 02/15/2005
• Est. Priority Date: 10/23/2001
• Status: Active Grant

• Current Assignee: ROHM Co., Ltd.
• Original Assignee: ROHM Co., Ltd.
• Inventors: Ichihara, Jun, Sai, Hironobu
• Primary Examiner(s): Wong, Don
• Assistant Examiner(s): Al-Nazer, Leith
• Application Number:
  US10/274,950
• Publication Number:
  US 20030076864A1
• Time in Patent Office: 847 Days
• Field of Search: 372 43- 46
• US Class Current: 372/43.01
• CPC Class Codes: H01S 5/02257 using windows, e.g. specially adapted for back-reflecting light to a detector inside the housing
• CPC Class Codes: H01S 5/02325 Mechanically integrated components on mount members or optical micro-benches
• CPC Class Codes: H01S 5/0683 by monitoring the optical output parameters
• CPC Class Codes: H01S 5/18311 using selective oxidation

Abstract

A lower multilayer reflection film (2), a light emitting layer forming portion (6) and an upper multilayer reflection film (8) are sequentially formed on a substrate (1) to form a semiconductor laminated portion (9), and a current injection region A is formed at a part of the semiconductor laminated portion so as to emit light from the surface in the center thereof. And, according to the present invention, the current injection region A is formed so as to be deflected from a center of the substrate. As a result, there is provided a surface light emitting type semiconductor laser capable of monitoring a light emitting power correctly and controlling it automatically in order to achieve the constant light emitting power in a case where the surface light emitting type laser chip is used as a light source for a pickup or the like.

Claims

1. A surface light emitting type semiconductor laser having a vertical cavity comprising:

a substrate; and

a semiconductor laminated portion which has a lower multilayer reflection film, a light emitting layer forming portion and an upper multilayer reflection film sequentially formed directly on said substrate, said semiconductor laminated portion having a current injection region being defined by current blocking region formed in a part of said semiconductor laminated portion,

wherein said semiconductor laminated portion has an outlet so as to emit a light from a surface of said current injection region, and said outlet is offset from a center of said substrate on which said semiconductor laminated portion is formed.

2. A semiconductor laser according to claim 1, wherein said substrate is in the form of a square and said current injection region is formed so as to be offset toward a corner of said square substrate.

3. A semiconductor laser according to claim 1, wherein said outlet is provided on a surface of said upper multilayer reflection film almost in a center of said current injection region and is formed so as to be away from the center of said substrate toward one side thereof by 20 μ

m or more.

4. A semiconductor laser according to claim 1, wherein said outlet is provided on a surface of said upper multilayer reflection film almost in a center of said current injection region and is formed so as to be away from the center of said substrate toward one side thereof by {fraction (1/9)} to ⅛

or more of a length of one side of said substrate.

5. A semiconductor laser according to claim 1, wherein said substrate is in the form of a square and said outlet is provided on a surface of said upper multilayer reflection film almost in a center of said current injection region and is formed at a position away from one end face of said substrate by 20 μ

m to 70 μ

m.

6. A semiconductor laser according to claim 1, wherein said light emitting layer forming portion has a structure in which an active layer is sandwiched by lower and upper spacer layers made of a semiconductor having a band gap larger than that of said active layer to confine a carrier in said active layer.

7. A semiconductor laser according to claim 6, wherein said active layer is of a quantum well structure.

8. A semiconductor laser according to claim 6, wherein said active layer and said spacer layers are formed of an AlGaAs based compound semiconductor.

9. A semiconductor laser according to claim 1, wherein said current injection region is formed by insulating a peripheral part of said light emitting layer forming portion by ion implantation.

10. A semiconductor laser according to claim 1, wherein said current injection region is formed by interposing a current blocking layer between said light emitting layer forming portion and said upperor lower multilayer reflection film for preventing current injection except in said current injection region.

11. A semiconductor laser according to claim 10, wherein said current blocking layer is made of AlAs and has an oxide region formed by oxidizing a peripheral part thereof to define said current injection region.

12. A semiconductor laser assembly comprising:

a stem;

a light receiving element mounted on one surface of said stem;

a surface light emitting type laser chip with a vertical cavity mounted on a surface of said light receiving element, said laser chip comprising a substrate, a semiconductor laminated portion which has a lower multilayer reflection film, a light emitting layer forming portion and an upper multilayer reflection film sequentially formed directly on said substrate, a current injection region being defined by a current blocking region formed in a part of said semiconductor laminated portion, said semiconductor laminated portion having an outlet so as to emit a light from a surface of said current injection region, and said outlet being offset from a center of said substrate on which said semiconductor laminated portion is formed; and

a cap having a light transmission window formed of a transparent body in a center thereof and attached to said stem so as to cover said laser chip and said light receiving element,

wherein said outlet is positioned so as to be under a center of said light transmission window.

13. A semiconductor laser assembly according to claim 12, wherein said light transmission window is disposed so as to be perpendicular to a laser beam radiated from said outlet.

14. A semiconductor laser assembly according to claim 12, wherein said laser chip is mounted on said light receiving element so that said outlet is positioned almost in a center of said light receiving element.