Surface emitting semiconductor laser, manufacturing method for surface emitting semiconductor laser, surface emitting semiconductor laser device, optical transmission device, and information processing device
A surface emitting semiconductor laser includes a first semiconductor multilayer reflector of a first conductivity type, an active area, a second semiconductor multilayer reflector of a second conductivity type, a current confinement layer having a conductive area and a surrounding high-resistance area, each provided on a substrate, and a higher-order transverse mode suppressing layer formed on an emission surface from which laser light is emitted and in an area in which higher-order transverse mode is induced. The higher-order transverse mode suppressing layer includes first to third insulation films having first to third refractive indices, respectively, formed on each other, and capable of transmitting an oscillation wavelength. The second refractive index is lower than the first refractive index. The third refractive index is higher than the second refractive index. The optical film thickness of the first to third insulation films is an odd number times one-fourth of the oscillation wavelength.
1. A surface emitting semiconductor laser including, provided on a substrate, a first semiconductor multilayer reflector of a first conductivity type, an active area, a second semiconductor multilayer reflector of a second conductivity type, and a current confinement layer having a conductive area and a surrounding high-resistance area, the surface emitting semiconductor laser comprising:
a higher-order transverse mode suppressing layer formed on an emission surface from which laser light is emitted and in an area in which higher-order transverse mode is induced,
wherein the higher-order transverse mode suppressing layer includes a first insulation film, a second insulation film formed on the first insulation film, and a third insulation film formed on the second insulation film, the first insulation film having a first refractive index and capable of transmitting an oscillation wavelength, the second insulation film having a second refractive index and capable of transmitting the oscillation wavelength, and the third insulation film having a third refractive index and capable of transmitting the oscillation wavelength, and
the second refractive index is lower than the first refractive index, the third refractive index is higher than the second refractive index, and an optical film thickness of the first insulation film, the second insulation film, and the third insulation film is an odd number times one-fourth of the oscillation wavelength.
2. The surface emitting semiconductor laser according to claim 1 , further comprising:
a fundamental transverse mode promoting layer formed on the emission surface from which laser light is emitted and in an area in which fundamental transverse mode is induced,
wherein the fundamental transverse mode promoting layer is positioned inside the higher-order transverse mode suppressing layer, and includes the second insulation film provided on a portion of the emission surface exposed by the first insulation film, and the third insulation film provided on the second insulation film.
3. The surface emitting semiconductor laser according to claim 1 ,
wherein the higher-order transverse mode suppressing layer has an inside diameter D 0 for exposure of the emission surface, and the conductive area of the current confinement layer has a diameter D 1 , D 1 being larger than D 0 .
4. The surface emitting semiconductor laser according to claim 1 ,
wherein a film thickness h 1 of the first insulation film meets the following relation:
h
1
=
λ
4
n
1
(
2
i
+
1
)
and
cos
[
2
π
h
1
λ
(
n
0
-
n
1
)
]
≥
0.8
where λ is the oscillation wavelength, n 1 is the refractive index of the first insulation film, i is an integer, and n 0 is the refractive index of air.
5. The surface emitting semiconductor laser according to claim 1 ,
wherein the reflectivity of the second semiconductor multilayer reflector, including the higher-order transverse mode suppressing layer, in an area in which the higher-order transverse mode suppressing layer is formed is lower by at least about 2% or more than the reflectivity of the second semiconductor multilayer reflector or the reflectivity of the second semiconductor multilayer reflector, including the fundamental transverse mode promoting layer, in an area in which the fundamental transverse mode promoting layer is formed.
6. The surface emitting semiconductor laser according to claim 1 , further comprising:
a columnar structure that leads to the current confinement layer,
wherein the third insulation film covers a bottom surface, a side surface, and a periphery of a top portion of the columnar structure.
7. The surface emitting semiconductor laser according to claim 1 ,
wherein the current confinement layer includes a conductive area and a surrounding selectively oxidized area, and the conductive area has a diameter D 1 of more than at least about 3 μm.
8. A manufacturing method for a surface emitting semiconductor laser including, provided on a substrate, a first semiconductor multilayer reflector of a first conductivity type, an active area, a second semiconductor multilayer reflector of a second conductivity type, and a current confinement layer having a conductive area and a surrounding high-resistance area, the manufacturing method comprising:
forming, on an emission surface from which laser light is emitted, a first insulation film having a first refractive index and capable of transmitting an oscillation wavelength;
forming an opening with an inside diameter D 0 in the first insulation film such that the first insulation film remains on the emission surface and in an area in which higher-order transverse mode is induced;
forming, on the first insulation film including the opening, a second insulation film having a second refractive index and capable of transmitting the oscillation wavelength; and
forming, on the second insulation film, a third insulation film having a third refractive index and capable of transmitting the oscillation wavelength,
the second refractive index is lower than the first refractive index, the third refractive index is higher than the second refractive index, and an optical film thickness of the first insulation film, the second insulation film, and the third insulation film is an odd number times one-fourth of the oscillation wavelength.
9. The manufacturing method according to claim 8 , further comprising:
forming a columnar structure that leads to the current confinement layer and selectively oxidizing the current confinement layer from a side surface of the columnar structure to form the high-resistance area,
wherein the conductive area has a diameter D 1 , D 1 being larger than D 0 .
10. The manufacturing method according to claim 8 ,
wherein the optical film thickness of the first insulation film is an integral multiple of nine-fourths of the oscillation wavelength.
11. The manufacturing method according to claim 9 , further comprising:
processing at least the third insulation film such that the processed third insulation film covers the area in which the higher-order transverse mode is induced and a bottom surface, a side surface, and a periphery of a top portion of the columnar structure.
12. A surface emitting semiconductor laser device comprising:
the surface emitting semiconductor laser according to claim 1 ; and
an optical member that receives light from the surface emitting semiconductor laser.
13. An optical transmission device comprising:
the surface emitting semiconductor laser device according to claim 12 ; and
a transmission unit that transmits via an optical medium laser light emitted from the surface emitting semiconductor laser device.
14. An information processing device comprising:
the surface emitting semiconductor laser according to claim 1 ;
a condensing device that condenses on a recording medium laser light emitted from the surface emitting semiconductor laser; and
a mechanism that scans the recording medium with the laser light condensed by the condensing device.