Separate confinement heterostructure laser device

• US 5,991,321 A
• Filed: 12/16/1997
• Issued: 11/23/1999
• Est. Priority Date: 12/21/1996
• Status: Expired due to Fees

• Current Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Original Assignee: Sharp Kabushiki Kaisha (Hon Hai Precision Industry Co., Ltd.)
• Inventors: Duggan, Geoffrey
• Primary Examiner(s): NGO, HUNG NHAT
• Application Number:
  US08/991,236
• Time in Patent Office: 707 Days
• Field of Search: 372/45, 372/46, 372/47, 372/48
• US Class Current: 372/45.01
• CPC Class Codes: H01S 5/20 Structure or shape of the semiconductor body to guide the optical wave ; Confining structures perpendicular to the optical axis, e.g. index or gain guiding, stripe geometry, broad area lasers, gain tailoring, transverse or lateral reflectors, special cladding structures, MQW barrier reflection layers
• CPC Class Codes: H01S 5/2004 Confining in the direction perpendicular to the layer structure
• CPC Class Codes: H01S 5/2009 by using electron barrier layers
• CPC Class Codes: H01S 5/2013 MQW barrier reflection layers

Abstract

A separate confinement heterostructure laser device has an optical guiding region, an active region in the optical guiding region, and p-type and n-type cladding regions on opposite sides of the optical guiding region. At least one barrier layer is present within the p-type cladding region. The composition of the barrier layer is such that it has an X-minimum higher than that of adjacent parts of the p-type cladding region. The composition and/or thickness of the barrier layer is also such that it has a Γ-minimum which is higher than the X-minima of the adjacent parts of the p-type, cladding region. The thickness of the barrier layer is such as to prevent electron tunneling between the X-bands of the adjacent parts of the p-type cladding region on opposite sides of the barrier layer, and/or the compositions of the adjacent parts of the p-type cladding region on opposite sides of the barrier layer are sufficiently different from one another to prevent such tunneling.

Claims

1. A separate confinement heterostructure laser device, comprising:

an optical guiding region;

an active region provided in the optical guiding region; and

n-type and p-type cladding regions provided on opposite sides of the optical guiding region,

wherein a first electron-reflecting barrier layer is provided in a p-side region of the laser device,

a composition of the first electron-reflecting barrier layer is set in such a manner that the first electron-reflecting barrier layer has an X-minimum which is higher than that in an adjacent portion of the p-side region at least on one selected side of the first electron-reflecting barrier layer, the selected side being disposed between the first electron-reflecting barrier layer and the active region, and

electron tunneling between X-bands of adjacent portions of the p-side region on opposite sides of the first electron-reflecting barrier layer is prevented by satisfying at least one of a first condition and a second condition, the first condition being such that a thickness of the first electron-reflecting barrier layer is set at a sufficient value for preventing the electron tunneling, and the second condition being such that parts of the p-side region on the opposite sides of the first electron-reflecting barrier layer have compositions which are sufficiently different from one another for preventing the electron tunneling.

2. A laser device according to claim 1, wherein the first electron-reflecting barrier layer is provided in the p-type cladding region.

3. A laser device according to claim 2, wherein:

the composition of the first electron-reflecting barrier layer is set in such a manner that the X-minimum of the first electron-reflecting barrier layer is higher than that in an adjacent portion of the p-type cladding region at least on a predetermined side of the first electron-reflecting barrier layer, the predetermined side being disposed between the first electron-reflecting barrier layer and the optical guiding region;

one of the composition and the thickness of the first electron-reflecting barrier layer is set in such a manner that the first electron-reflecting barrier layer has a Γ

-minimum which is higher than the X-minimum of the adjacent portion of the p-type cladding region; and

electron tunneling between X-bands of adjacent portions of the p-type cladding region on the opposite sides of the first electron-reflecting barrier layer is prevented by satisfying at least one of condition (a) and condition (b), the condition (a) being such that the thickness of the first electron-reflecting barrier layer is set at a sufficient value for preventing the electron tunneling, and the condition (b) being such that the adjacent portions of the p-type cladding region on the opposite sides of the first electron-reflecting barrier layer have compositions which are sufficiently different from one another for preventing the electron tunneling.

4. A laser device according to claim 2, wherein:

the composition of the first electron-reflecting barrier layer is set in such a manner that the X-minimum of the first electron-reflecting barrier layer is higher than that in adjacent portions of the p-type cladding region on both sides of the first electron-reflecting barrier layer;

one of the composition and the thickness of the first electron-reflecting barrier layer is set in such a manner that the first electron-reflecting barrier layer has a Γ

-minimum which is higher than the X-minima of the adjacent portions of the p-type cladding region on the both sides of the first electron-reflecting barrier layer; and

electron tunneling between X-bands of the adjacent portions of the p-type cladding region on the opposite sides of the first electron-reflecting barrier layer is prevented by satisfying at least one of condition (a) and condition (b), the condition (a) being such that the thickness of the first electron-reflecting barrier layer is set at a sufficient value for preventing the electron tunneling, and the condition (b) being such that the adjacent portions of the p-type cladding region on the opposite sides of the first electron-reflecting barrier layer have compositions which are sufficiently different from one another for preventing the electron tunneling.

5. A laser device according to claim 2, wherein a thickness of a part of the p-type cladding region disposed between the first electron-reflecting barrier layer and the optical guiding region is not less than 100 Å

.

6. A laser device according to claim 2, wherein a thickness of a part of the p-type cladding region disposed between the first electron-reflecting barrier layer and the optical guiding region is in the range from 100 Å

to 1 μ

m.

7. A laser device according to claim 2, wherein the thickness of the first electron-reflecting barrier layer is 20 Å

to 3 Å

.

8. A laser device according to claim 7, wherein the thickness of the first electron-reflecting barrier layer is 15 Å

to 7 Å

.

9. A laser device according to claim 2, wherein the thickness of the first electron-reflecting barrier layer is set in such a manner that a first confined electron state therein lies above that of the X-minima in adjacent parts of the cladding region and the optical guiding region.

10. A laser device according to claim 1, wherein the first electron-reflecting barrier layer is provided in a p-side portion of the optical guiding region.

11. A laser device according to claim 10, wherein the thickness of the first electron-reflecting barrier layer is 5 Å

to 50 Å

.

12. A laser device according to claim 10, wherein the thickness of the first electron-reflecting barrier layer is 5 Å

to 10 Å

.

13. A laser device according to claim 1, wherein the first electron-reflecting barrier layer has substantially the same composition as that of the active region.

14. A laser device according to claim 1, wherein at least one additional electron-reflecting barrier layer is further provided in the p-side region of the laser device.

15. A laser device according to claim 14, wherein the at least one additional electron-reflecting barrier layer is provided in the same portion of the p-side region of the laser device as that in which the first electron-reflecting barrier layer is provided.

16. A laser device according to claim 14, wherein the at least one additional electron-reflecting barrier layer is provided in a different portion of the p-side region of the laser device from that in which the first electron-reflecting barrier layer is provided.

17. A laser device according to claim 14, wherein thicknesses of the at least one additional electron-reflecting barrier layer and the first electron-reflecting barrier layer are set so as to decrease in a direction away from the active region.

18. A laser device according to claim 14, wherein a separation region separating adjacent two of the electron-reflecting barrier layers is not less than 2.85 Å

.

19. A laser device according to claim 18, wherein the separation region is in the range from 7 Å

to 15 Å

.

20. A laser device according to claim 1, wherein the laser device is provided based on an alloy system of GaInP/(AlGaIn)P.

21. A laser device according to claim 20, wherein the alloy system is represented as (In_x Ga_1-x)P/(Al_y Ga_1-y)_z In_1-z P, where 0.3≦

×

≦

0.6, y is in the range from 0 to 1, and z is in the range from 0.3 to 0.6.

22. A laser device according to claim 21, wherein a value of z is selected to ensure that the alloy system of (AlGa)_z In_1-z P has the same lattice constant as GaAs.

23. A laser device according to claim 21, wherein a value of z is 0.515.

24. A laser device according to claim 1, wherein the laser device is provided based on an alloy system of AlGaAs.

25. A laser device according to claim 24, wherein the alloy system is represented as GaAs/(Al_x Ga_1-x)As, where x is in the range from 0 to 1.

26. A laser device according to claim 1, wherein the laser device is of a Graded Refractive Index Separate Confinement Heterostructure type.

27. A laser device according to claim 1, wherein the laser device is of an edge-emitting type.

28. A laser device according to claim 1, wherein the laser device is of a surface-emitting type.