Vertical-cavity surface-emitting semiconductor laser

Details Vertical-cavity surface-emitting semiconductor laser Vertical-cavity surface-emitting semiconductor laser

1999-02-24

2003-04-15

Leung, Quyen (Department: 2828)

Coherent light generators

Particular active media

Semiconductor

C372S096000

Reexamination Certificate

active

06549553

ABSTRACT:

This application is based on Patent Application No. 10-43383 filed Feb. 25, 1998 in Japan, the content of which is incorporated hereinto by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a process for fabricating a vertical-cavity surface-emitting semiconductor laser, which is useful as an optical source for optical interconnection that optically connects chips or boards to each other or for conducting two-dimensional parallel signal processing, and to a vertical-cavity surface-emitting semiconductor laser.
2. Description of the Related Art
Vertical-cavity surface-emitting semiconductor lasers, which are easy to construct a two-dimensional array and enables high efficient coupling with fibers without use of lenses for coupling because of their illumination pattern being circular, are considered important as an optical source for optical interconnection or two-dimensional parallel signal processing and also important for the purpose of reducing power consumption because they permit extreme lowering of threshold current by means of an ultrafine-cavity structure.
FIG. 1
is a cross-sectional view showing a conventional vertical-cavity surface-emitting semiconductor laser along the direction vertical to a crystal face thereof (cf. (1) B.-S. Yoo, H. Y. Chu, H.-H. Park, H. G. Lee and J. Lee, IEEE Journal of Quantum Electronics, vol. 33, No. 10, 1997, pp. 1794-1800; and (2) C. Chang-Hasnain, Y. A., Wu, G. S. Li, G. Hasnain, K. D. Choquette, C. Caneau and L. T. Florez, Applied Physics Letters, vol. 63, No. 10, 1993, pp. 1307-1309). The laser of
FIG. 1
comprises devices including a p-GaAs substrate
101
, which has thereon in order a p-Al
y
Ga
1−y
As/Al
z
Ga
1−z
As (0<y<z) distributed Bragg reflector (DBR) mirror
102
(the dashed portion showing Al
z
Ga
1−z
As and the white portion showing Al
y
Ga
1−y
As), a non-doped Al
w
Ga
1−w
As lower spacer layer
103
, a GaAs/Al
x
Ga
1−x
As (x≦w) multiple quantum well active layer
104
, a non-doped Al
w
Ga
1−w
As upper spacer layer
105
, an n-Al
y
Ga
1−y
As/Al
z
Ga
1−z
As (0<y<z) DBR mirror
106
, a semiconductor buried layer
107
, a lower electrode
108
, an insulator
109
, an upper electrode
110
, and an element separating structure
111
. The respective layers of DBR are set to a thickness corresponding to one fourth of the quotient obtained by dividing the lasing wavelength by the refractive index of each layer.
Among the devices shown in
FIG. 1
, an AlGaAs/AlGaAs n-i-p-i structure or an amorphous GaAs layer has been reported as the buried layer
107
, each exhibiting single transverse mode lasing operation. However, the above-described structures do not achieve optical constriction due to refractive index optical waveguide but are of an anti-guide waveguide structure. Therefore, in principle, a plurality of transverse modes can occur but not a single transverse mode. In this case, higher order transverse modes are cut off to achieve a single transverse mode operation by utilizing the outer portion of the waveguide having a higher loss. However, in dynamic characteristics in which the carrier density inside the active layer varies widely, there arises the problem that an unstable operation occurs, that is, higher order modes may emerge depending on the carrier density distribution in the active layer.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide a vertical-cavity surface-emitting semiconductor laser which provides single transverse mode operation that is dynamically stable as compared with a conventional vertical-cavity surface-emitting semiconductor laser.
A second object of the present invention is to provide a vertical-cavity surface-emitting semiconductor laser having a smaller element volume than a conventional vertical-cavity surface-emitting semiconductor laser which provides high speed modulation characteristics and provides single transverse mode operation that is dynamically stable as compared with a conventional vertical-cavity surface-emitting semiconductor laser.
A third object of the present invention is to provide a process for fabricating a vertical-cavity surface-emitting semiconductor laser of which transverse mode is single and dynamically more stable than a conventional vertical-cavity surface-emitting semiconductor laser.
A fourth object of the present invention is to provide a process for fabricating a vertical-cavity surface-emitting semiconductor laser having a smaller element volume than a conventional vertical-cavity surface-emitting semiconductor laser which provides high speed modulation characteristics and provides single transverse mode operation that is dynamically stable as compared with a conventional vertical-cavity surface-emitting semiconductor laser.
The above and the other objects, effects, features and advantages of the present invention will become more apparent from the following description of embodiments thereof taken in conjunction with the accompanying drawings.


REFERENCES:
patent: 5212701 (1993-05-01), Choquette et al.
patent: 5530715 (1996-06-01), Shieh et al.
patent: 5577064 (1996-11-01), Swirhun et al.
patent: 5864575 (1999-01-01), Ohiso et al.
patent: 0784363 (1997-07-01), None
patent: 0820131 (1998-02-01), None
patent: 1-42879 (1989-02-01), None
patent: 1-264285 (1989-10-01), None
patent: 2-52485 (1990-02-01), None
patent: WO93/22813 (1993-11-01), None
“Transverse Mode Characteristics of Vertical-Cavity Surface-Emitting Lasers Buried in Amorphous GaAs Antiguide Layer” Yoo et al. IEEE Journal of Quantum Electronics, vol. 33, No. 10, Oct. 1997, pp. 1794-1800.
“Low threshold buried heterostructure vertical cavity surface emitting laser” Chang-Hasnain et al. Appl. Phys. Lett. 63 (10) Sep. 6, 1993 pp. 1307-1309.
“High-frequency modulation of oxide-confined vertical cavity surface emitting lasers” Lear et al. Electronics Letters Feb. 29, 1996, vol. 32, No. 5. pp. 457-458.

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