Vertical-cavity surface-emitting laser diode (VCSEL), method for fabricating VCSEL, and optical transmission apparatus

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.

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.

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.

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.

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.

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.