Surface-emitting semiconductor laser, surface-emitting semiconductor laser device, optical transmission device, and information processing device

1. A surface-emitting semiconductor laser comprising:

a substrate;

a first semiconductor multilayer reflector of a first conductivity type formed on the substrate, the first semiconductor multilayer reflector including a plurality of pairs of a low-refractive-index layer and a high-refractive-index layer;

a cavity region formed on the first semiconductor multilayer reflector;

a second semiconductor multilayer reflector of a second conductivity type formed on the cavity region, the second semiconductor multilayer reflector including a plurality of pairs of a low-refractive-index layer and a high-refractive-index layer;

a columnar structure extending from the second semiconductor multilayer reflector to the cavity region; and

a current confinement layer formed inside the columnar structure by selective oxidation of a semiconductor layer containing Al,

wherein the cavity region includes

an active region; and

a cavity extension region interposed between the active region and the first semiconductor multilayer reflector,

wherein the bottom of the columnar structure is positioned within the cavity extension region in the film-thickness direction,

wherein the cavity extension region is composed of Al x Ga 1-x As, where x represents an Al content, the Al content being set such that the cavity extension region is not substantially subject to oxidation or the degree of oxidation of the cavity extension region is negligible, and

wherein the low-refractive-index layer constituting the first semiconductor multilayer reflector has an Al content equal to or higher than an Al content in the current confinement layer.

2. The surface-emitting semiconductor laser according to claim 1 ,

wherein a concentration of an impurity of the first conductivity type in the cavity extension region is lower than an impurity concentration in the first semiconductor multilayer reflector.

3. The surface-emitting semiconductor laser according to claim 1 ,

wherein the cavity extension region further includes a carrier block layer adjacent to the active region, the carrier block layer having a higher Al content than the active region.

4. The surface-emitting semiconductor laser according to claim 1 ,

wherein the cavity extension region is composed of Al x Ga 1-x As, where x≦0.95.

5. The surface-emitting semiconductor laser according to claim 3 ,

wherein the carrier block layer is composed of Al y Ga 1-y As, where 0.8<y≦0.95.

6. The surface-emitting semiconductor laser according to claim 3 ,

wherein the carrier block layer has a higher impurity concentration than any other region constituting the cavity extension region.

7. The surface-emitting semiconductor laser according to claim 3 ,

wherein the carrier block layer has a lower Al content than any other region constituting the cavity extension region.

8. The surface-emitting semiconductor laser according to claim 3 ,

wherein the carrier block layer has a higher Al content than any other region constituting the cavity extension region.

9. The surface-emitting semiconductor laser according to claim 3 ,

wherein a concentration of an impurity of the first conductivity type in the carrier block layer is lower than an impurity concentration in the first semiconductor multilayer reflector.

10. The surface-emitting semiconductor laser according to claim 1 ,

wherein the cavity extension region has a thickness larger than a range of production fluctuations resulting from etching of the columnar structure.

11. The surface-emitting semiconductor laser according to claim 1 ,

wherein the cavity extension region has an optical thickness equal to an integral multiple of λ/4, where λ represents oscillation wavelength.

12. The surface-emitting semiconductor laser according to claim 1 ,

wherein the cavity extension region has an optical thickness equal to or less than 26λ/4, where λ represents oscillation wavelength.

13. The surface-emitting semiconductor laser according to claim 1 ,

wherein the cavity extension region has an optical thickness equal to or less than 12λ/4, where λ represents oscillation wavelength.

14. The surface-emitting semiconductor laser according to claim 3 ,

wherein the carrier block layer has an optical thickness equal to an integral multiple of λ/4, where λ represents oscillation wavelength.

15. The surface-emitting semiconductor laser according to claim 1 ,

wherein the low-refractive-index layer constituting the first semiconductor multilayer reflector is composed of AlAs.

16. A surface-emitting semiconductor laser device comprising:

the surface-emitting semiconductor laser according to claim 1 ; and

an optical element that light emitted by the surface-emitting semiconductor laser enters.

17. An optical transmission device comprising:

the surface-emitting semiconductor laser device according to claim 16 ; and

a transmission unit that transmits a laser beam emitted by the surface-emitting semiconductor laser device via an optical medium.

18. An information processing device comprising:

the surface-emitting semiconductor laser according to claim 1 ;

a light-condensing unit that condenses a laser beam emitted by the surface-emitting semiconductor laser on a recording medium; and

a mechanism that scans the recording medium with the laser beam condensed by the light-condensing unit.