Vertical-cavity surface-emitting laser diode (VCSEL), method for fabricating VCSEL, and optical transmission apparatus
View Patent ↗Provided is a VCSEL that includes a lower DBR of a first conductivity type, an active region, and an upper DBR of a second conductivity type, on a substrate. The lower DBR has a first to-be-oxidized Al-containing layer located farther from the active region than a second to-be-oxidized layer that is formed in the upper DBR. Both layers have an oxidized region and a first or a second non-oxidized region surrounded by the oxidized region. The first non-oxidized region is larger than the maximum size of the second non-oxidized region for a single mode oscillation, and smaller than the maximum size of the first non-oxidized region for a single mode oscillation. The second non-oxidized region is larger than the maximum size of the second non-oxidized region for a single mode oscillation. The first non-oxidized region has a size equal to or larger than that of the second non-oxidized region.
1. A vertical-cavity surface-emitting laser diode (VCSEL) comprising:
a first semiconductor multilayer film reflective mirror of a first conductivity type that includes a stacked structure of a high-Al refractive index layer having a high Al-composition and a low-Al refractive index layer having a lower Al-composition than the high-Al refractive index layer, an active region that includes a light emitting layer, and a second semiconductor multilayer film reflective mirror of a second conductivity type that includes a stacked structure of a high-Al refractive index layer having a high Al-composition and a low-Al refractive index layer having a lower Al-composition than the high-Al refractive index layer, on a substrate;
a mesa structure or a trench structure being formed from the second semiconductor multilayer film reflective mirror to at least a portion of the first semiconductor multilayer film reflective mirror;
a first to-be-oxidized Al-containing layer being formed in the first semiconductor multilayer film reflective mirror and having a higher Al-composition than the high-Al refractive index layer of the first semiconductor multilayer film reflective mirror; and
a second to-be-oxidized Al-containing layer being formed in the second semiconductor multilayer film reflective mirror or between the active region and the second semiconductor multilayer film reflective mirror, and having a higher Al-composition than the high-Al refractive index layer of the second semiconductor multilayer film reflective mirror,
the first to-be-oxidized Al-containing layer being formed farther from the active region than the second to-be-oxidized Al-containing layer;
the first to-be-oxidized Al-containing layer having a first oxidized region oxidized from a side surface of the mesa or trench structure, and a first non-oxidized region surrounded by the first oxidized region;
the second to-be-oxidized Al-containing layer having a second oxidized region oxidized from a side surface of the mesa or trench structure, and a second non-oxidized region surrounded by the second oxidized region,
the size of the first non-oxidized region being larger than the maximum size of the second non-oxidized region that provides a single mode oscillation, and smaller than the maximum size of the first non-oxidized region that provides a single mode oscillation,
the size of the second non-oxidized region being larger than the maximum size of the second non-oxidized region that provides a single mode oscillation, and
the size of the first non-oxidized region being equal to or larger than the size of the second non-oxidized region.
2. The VCSEL according to claim 1 , wherein the first conductivity type is n-type, and the second conductivity type is p-type.
3. A vertical-cavity surface-emitting laser diode (VCSEL) comprising:
a first semiconductor multilayer film reflective mirror of a first conductivity type that includes a stacked structure of a high-Al refractive index layer having a high Al-composition and a low-Al refractive index layer having a lower Al-composition than the high-Al refractive index layer, an active region that includes a light emitting layer, and a second semiconductor multilayer film reflective mirror of a second conductivity type that includes a stacked structure of a high-Al refractive index layer having a high Al-composition and a low-Al refractive index layer having a lower Al-composition than the high-Al refractive index layer, on a substrate;
a mesa structure or a trench structure being formed from the second semiconductor multilayer film reflective mirror to at least a portion of the first semiconductor multilayer film reflective mirror;
a first to-be-oxidized Al-containing layer being formed in the first semiconductor multilayer film reflective mirror or between the active region and the first semiconductor multilayer film reflective mirror, and having a higher Al-composition than the high-Al refractive index layer of the first semiconductor multilayer film reflective mirror; and
a second to-be-oxidized Al-containing layer being formed in the second semiconductor multilayer film reflective mirror and having a higher Al-composition than the high-Al refractive index layer of the second semiconductor multilayer film reflective mirror,
the second to-be-oxidized Al-containing layer being formed farther from the active region than the first to-be-oxidized Al-containing layer,
the first to-be-oxidized Al-containing layer having a first oxidized region oxidized from a side surface of the mesa or trench structure, and a first non-oxidized region surrounded by the first oxidized region,
the second to-be-oxidized Al-containing layer having a second oxidized region oxidized from a side surface of the mesa or trench structure, and a second non-oxidized region surrounded by the second oxidized region,
the size of the first non-oxidized region being larger than the maximum size of the first non-oxidized region that provides a single mode oscillation,
the size of the second non-oxidized region being larger than the maximum size of the first non-oxidized region that provides a single mode oscillation, and smaller than the maximum size of the second non-oxidized region that provides a single mode oscillation, and
the size of the second non-oxidized region being equal to or larger than the size of the first non-oxidized region.
4. The VCSEL according to claim 3 , wherein the first conductivity type is p-type, and the second conductivity type is n-type.
5. A vertical-cavity surface-emitting laser diode (VCSEL) comprising:
a first semiconductor multilayer film reflective mirror of a first conductivity type that includes a stacked structure of a high-Al refractive index layer having a high Al-composition and a low-Al refractive index layer having a lower Al-composition than the high-Al refractive index layer, an active region that includes a light emitting layer, and a second semiconductor multilayer film reflective mirror of a second conductivity type that includes a stacked structure of a high-Al refractive index layer having a high Al-composition and a low-Al refractive index layer having a lower Al-composition than the high-Al refractive index layer, on a substrate;
a mesa structure or a trench structure being formed at least in the second semiconductor multilayer film reflective mirror; and
a first and a second to-be-oxidized Al-containing layers being formed in the second semiconductor multilayer film reflective mirror or between the active region and the second semiconductor multilayer film reflective mirror, and having a higher Al-composition than the high-Al refractive index layer of the second semiconductor multilayer film reflective mirror,
the first to-be-oxidized Al-containing layer being formed farther from the active region than the second to-be-oxidized Al-containing layer,
the first to-be-oxidized Al-containing layer having a first oxidized region oxidized from a side surface the mesa or trench structure, and a first non-oxidized region surrounded by the first oxidized region,
the second to-be-oxidized Al-containing layer having a second oxidized region oxidized from a side surface of the mesa or trench structure, and a second non-oxidized region surrounded by the second oxidized region,
the size of the first non-oxidized region being larger than the maximum size of the second non-oxidized region that provides a single mode oscillation, and smaller than the maximum size of the first non-oxidized region that provides a single mode oscillation, and
the size of the second non-oxidized region being larger the maximum size of the second non-oxidized region that provides a single mode oscillation.
6. The VCSEL according to claim 5 , wherein the first conductivity type is n-type, and the second conductivity type is p-type.
7. A vertical-cavity surface-emitting laser diode (VCSEL) comprising:
a first semiconductor multilayer film reflective mirror of a first conductivity type that includes a stacked structure of a high-Al refractive index layer having a high Al-composition and a low-Al refractive index layer having a lower Al-composition than the high-Al refractive index layer, an active region that includes a light emitting layer, and a second semiconductor multilayer film reflective mirror of a second conductivity type that includes a stacked structure of a high-Al refractive index layer having a high Al-composition and a low-Al refractive index layer having a lower Al-composition than the high-Al refractive index layer, on a substrate;
a mesa structure or a trench structure being formed from the second semiconductor multilayer film reflective mirror to at least a portion of the first semiconductor multilayer film reflective mirror; and
a first and a second to-be-oxidized Al-containing layers being formed in the first semiconductor multilayer film reflective mirror or between the active region and the first semiconductor multilayer film reflective mirror, and having a higher Al-composition than the high-Al refractive index layer of the first semiconductor multilayer film reflective mirror,
the second to-be-oxidized Al-containing layer being formed farther from the active region than the first to-be-oxidized Al-containing layer,
the first to-be-oxidized Al-containing layer having a first oxidized region oxidized from a side surface the mesa or trench structure, and a first non-oxidized region surrounded by the first oxidized region,
the second to-be-oxidized Al-containing layer having a second oxidized region oxidized from a side surface the mesa or trench structure, and a second non-oxidized region surrounded by the second oxidized region,
the size of the first non-oxidized region being larger than the maximum size of the first non-oxidized region that provides a single mode oscillation, and
the size of the second non-oxidized region being larger than the maximum size of the first non-oxidized region that provides a single mode oscillation, and smaller than the maximum size of the second non-oxidized region that provides a single mode oscillation.
8. The VCSEL according to claim 7 , wherein the first conductivity type is p-type, and the second conductivity type is n-type.
9. A vertical-cavity surface-emitting laser diode (VCSEL) comprising:
a first semiconductor multilayer film reflective mirror of a first conductivity type that includes a stacked structure of a high-Al refractive index layer having a high Al-composition and a low-Al refractive index layer having a lower Al-composition than the high-Al refractive index layer, an active region that includes a light emitting layer, and a second semiconductor multilayer film reflective mirror of a first conductivity type that includes a stacked structure of a high-Al refractive index layer having a high Al-composition and a low-Al refractive index layer having a lower Al-composition than the high-Al refractive index layer, on a substrate;
a mesa structure or a trench structure being formed from the second semiconductor multilayer film reflective mirror to at least a portion of the first semiconductor multilayer film reflective mirror; and
a to-be-oxidized Al-containing layers being formed in the first semiconductor multilayer film reflective mirror and having a higher Al-composition than the high-Al refractive index layer of the first semiconductor multilayer film reflective mirror; and
a tunneling junction region being formed in the first semiconductor multilayer film reflective mirror or between the active region and the first semiconductor multilayer film reflective mirror,
the to-be-oxidized Al-containing layer being formed farther from the active region than the tunneling junction region,
the to-be-oxidized Al-containing layer having an oxidized region oxidized from a side surface the mesa or trench structure, and a non-oxidized region surrounded by the oxidized region, and
the size of the non-oxidized region being smaller than the maximum size of the non-oxidized region that provides a single mode oscillation.
10. A vertical-cavity surface-emitting laser diode (VCSEL) comprising:
a first semiconductor multilayer film reflective mirror of a first conductivity type that includes a stacked structure of a high-Al refractive index layer having a high Al-composition and a low-Al refractive index layer having a lower Al-composition than the high-Al refractive index layer, an active region that includes a light emitting layer, and a second semiconductor multilayer film reflective mirror of a first conductivity type that includes a stacked structure of a high-Al refractive index layer having a high Al-composition and a low-Al refractive index layer having a lower Al-composition than the high-Al refractive index layer, on a substrate;
a mesa structure or a trench structure being formed at least in the second semiconductor multilayer film reflective mirror;
a to-be-oxidized Al-containing layer being formed in the second semiconductor multilayer film reflective mirror and having a higher Al-composition than the high-Al refractive index layer of the second semiconductor multilayer film reflective mirror; and
a tunneling junction region being formed in the second semiconductor multilayer film reflective mirror or between the active region and the second semiconductor multilayer film reflective mirror,
the to-be-oxidized Al-containing layer being formed farther from the active region than the tunneling junction region,
the to-be-oxidized Al-containing layer having an oxidized region oxidized from a side surface of the mesa or trench structure, and a non-oxidized region surrounded by the oxidized region, and
the size of the non-oxidized region being smaller than the maximum size of the non-oxidized region that provides a single mode oscillation.
11. The VCSEL according to claim 9 , wherein the first conductivity type is n-type, and the tunneling junction region comprises an n-type tunneling layer having a high impurity concentration, and a p-type tunneling layer having a high impurity concentration.
12. A method for fabricating a vertical-cavity surface-emitting laser diode (VCSEL) comprising:
forming, on a substrate, a first semiconductor multilayer film reflective mirror of a first conductivity type that includes a stacked structure of a high-Al refractive index layer having a high Al-composition and a low-Al refractive index layer having a lower Al-composition than the high-Al refractive index layer, an active region, and a second semiconductor multilayer film reflective mirror of a second conductivity type that includes a stacked structure of a high-Al refractive index layer having a high Al-composition and a low-Al refractive index layer having a lower Al-composition than the high-Al refractive index layer, and forming a first and a second to-be-oxidized Al-containing layers having a higher Al-composition than the high-Al refractive index layer of the first and second semiconductor multilayer film reflective mirrors and having a same film thickness and composition such that the first to-be-oxidized Al-containing layer being formed farther from the active region than the second Al-containing layer;
forming a mesa structure or a trench structure on the substrate such that at least the side surfaces of the first and second to-be-oxidized Al-containing layers are exposed; and
oxidizing the first and second to-be-oxidized Al-containing layers from a side surface of the mesa or trench structure and forming a first and a second non-oxidized regions in the first and second to-be-oxidized Al-containing layers,
the size of the second non-oxidized region being larger than the maximum size of the second non-oxidized region that provides a single mode oscillation,
the size of the first non-oxidized region being larger than the maximum size of the second non-oxidized region that provides a single mode oscillation, and smaller than the maximum size of the first non-oxidized region that provides a single mode oscillation, and
the size of the first non-oxidized region being equal or larger than the size of the second non-oxidized region.
13. An optical transmission apparatus comprising: the VCSEL according to claim 1 , a coupling material that is electrically coupled to an electrode formed on an emission surface of the VCSEL, and an optical fiber that has an incidence surface opposing to the emission surface of the VCSEL and transmits light emitted from the incidence surface, wherein
if the opening diameter of the emission surface of the VCSEL is D, the distance between the emission surface of the VCSEL and the incidence surface of the optical fiber is h, the maximum divergence angle of the light emitted from the VCSEL is 2θ, and the core diameter of the optical fiber is d, then the relation as follows is obtained,
d>D +(2 ×h ×tan θ).