Semiconductor optical device
There are included: a second semiconductor layer of a second conduction-type formed to be on and in contact with the active layer; and a third semiconductor layer of a second conduction-type formed on the second semiconductor layer, the third semiconductor layer is arranged above a formation region of the active layer, a bottom surface of the third semiconductor layer is arranged in the formation region of the active layer, and a width of the third semiconductor layer, on the active layer side, in a direction perpendicular to a waveguide direction and parallel to a plane of a substrate is set to be smaller than a width of the active layer in the same direction.
1 . A semiconductor optical device comprising:
a first low refractive index layer on a substrate, the first low refractive index layer having a lower refractive index than a semiconductor;
a first semiconductor layer of a first conduction-type on the first low refractive index layer;
an active layer on the first semiconductor layer;
a second semiconductor layer of a second conduction-type on and in contact with the active layer, the second semiconductor layer forming a first ridge pattern with the active layer;
a third semiconductor layer on the second semiconductor layer and above the active layer, the third semiconductor layer forming a second ridge pattern;
a fourth semiconductor layer on the first semiconductor layer and being in contact with first lateral faces of the first ridge pattern, the fourth semiconductor layer being non-electroconductive;
a fifth semiconductor layer on the first semiconductor layer and in contact with second lateral faces of the first ridge pattern, the fifth semiconductor layer being non-electroconductive;
a second low refractive index layer on the fourth semiconductor layer, the second low refractive index layer having a lower refractive index than a semiconductor and being in contact with first lateral faces of the second ridge pattern;
a third low refractive index layer on the fifth semiconductor layer, the third low refractive index layer having a lower refractive index than a semiconductor and being in contact with second lateral faces of the second ridge pattern;
a first electrode formed directly on the first semiconductor layer and electrically connected to the first semiconductor layer; and
a second electrode electrically connected to the third semiconductor layer, wherein a width of the third semiconductor layer, on the active layer side, in a width direction, which is perpendicular to a waveguide direction and parallel to a plane of the substrate, is smaller than a width of the active layer in the width direction.
2 . The semiconductor optical device according to claim 1 , wherein the fourth semiconductor layer comprises i-type InP.
3 . The semiconductor optical device according to claim 1 , wherein the fourth semiconductor layer comprises InP doped with Fe.
4 . The semiconductor optical device according to claim 1 , wherein the second electrode is disposed on the third semiconductor layer via a contact layer.
5 . The semiconductor optical device according to claim 1 , wherein the active layer and the second semiconductor layer have a same area in a plan view, and wherein the second semiconductor layer overlaps with the active layer in the plan view.
6 . The semiconductor optical device according to claim 1 , wherein a refractive index of the second semiconductor layer is a refractive index between those of the third semiconductor layer and the active layer.
7 . The semiconductor optical device according to claim 1 , further comprising:
a core buried in the first low refractive index layer in a region below the active layer.
8 . The semiconductor optical device according to claim 1 , further comprising:
a diffraction grating buried in the first low refractive index layer in a region below the active layer.
9 . The semiconductor optical device according to claim 1 , wherein the first low refractive index layer is an insulating material.
10 . The semiconductor optical device according to claim 1 , wherein the first low refractive index layer is composed of silicon oxide and/or silicon nitride.
11 . A semiconductor optical device comprising:
a first low refractive index layer on a substrate, the first low refractive index layer having a lower refractive index than a semiconductor;
a first semiconductor layer of a first conduction-type on the first low refractive index layer;
an active layer on the first semiconductor layer;
a second semiconductor layer of a second conduction-type on and in contact with the active layer, the second semiconductor layer forming a first ridge pattern with the active layer;
a third semiconductor layer on the second semiconductor layer and above the active layer, the third semiconductor layer forming a second ridge pattern;
a fourth semiconductor layer on the first semiconductor layer and being in contact with first lateral faces of the first ridge pattern, the fourth semiconductor layer comprising i-type InP or InP doped with Fe;
a fifth semiconductor layer on the first semiconductor layer and in contact with second lateral faces of the first ridge pattern, the fifth semiconductor layer comprising i-type InP or InP doped with Fe;
a second low refractive index layer on the fourth semiconductor layer, the second low refractive index layer having a lower refractive index than a semiconductor and being in contact with first lateral faces of the second ridge pattern;
a third low refractive index layer on the fifth semiconductor layer, the third low refractive index layer having a lower refractive index than a semiconductor and being in contact with second lateral faces of the second ridge pattern;
a first electrode formed directly on the first semiconductor layer and electrically connected to the first semiconductor layer; and
a second electrode electrically connected to the third semiconductor layer, wherein a width of the third semiconductor layer, on the active layer side, in a width direction, which is perpendicular to a waveguide direction and parallel to a plane of the substrate, is smaller than a width of the active layer in the width direction.
12 . The semiconductor optical device according to claim 11 , wherein the second electrode is on the third semiconductor layer via a contact layer.
13 . The semiconductor optical device according to claim 11 , wherein the active layer and the second semiconductor layer have a same area in a plan view, and the second semiconductor layer overlaps with the active layer in the plan view.
14 . The semiconductor optical device according to claim 11 , wherein a refractive index of the second semiconductor layer is a refractive index between those of the third semiconductor layer and the active layer.
15 . The semiconductor optical device according to claim 11 , wherein the first low refractive index layer is an insulating material.
16 . The semiconductor optical device according to claim 11 , wherein the first low refractive index layer is composed of silicon oxide and/or silicon nitride.
17 . A semiconductor optical device comprising:
a first low refractive index layer on a substrate, the first low refractive index layer having a lower refractive index than a semiconductor;
a first semiconductor layer of a first conduction-type on the first low refractive index layer;
an active layer on the first semiconductor layer;
a second semiconductor layer of a second conduction-type on and in contact with the active layer;
a third semiconductor layer on the second semiconductor layer and above the active layer, the third semiconductor layer forming a ridge pattern;
a second low refractive index layer on the second semiconductor layer, the second low refractive index layer having a lower refractive index than a semiconductor and being in contact with first lateral faces of the ridge pattern of the third semiconductor layer;
a third low refractive index layer on the second semiconductor layer, the third low refractive index layer having a lower refractive index than a semiconductor and being in contact with second lateral faces of the ridge pattern of the third semiconductor layer;
a first electrode formed directly on the first semiconductor layer and electrically connected to the first semiconductor layer;
a second electrode electrically connected to the third semiconductor layer; and
a core buried in the first low refractive index layer in a region below the active layer, wherein
a width of the third semiconductor layer, on the active layer side, in a width direction, which is perpendicular to a waveguide direction and parallel to a plane of the substrate, is smaller than a width of the active layer in the width direction.
18 . A semiconductor optical device comprising:
a first low refractive index layer on a substrate, the first low refractive index layer having a lower refractive index than a semiconductor;
a first semiconductor layer of a first conduction-type on the first low refractive index layer;
an active layer on the first semiconductor layer;
a second semiconductor layer of a second conduction-type on and in contact with the active layer;
a third semiconductor layer on the second semiconductor layer and above the active layer, the third semiconductor layer forming a ridge pattern;
a second low refractive index layer on the second semiconductor layer, the second low refractive index layer having a lower refractive index than a semiconductor and being in contact with first lateral faces of the ridge pattern of the third semiconductor layer;
a third low refractive index layer on the second semiconductor layer, the third low refractive index layer having a lower refractive index than a semiconductor and being in contact with second lateral faces of the ridge pattern of the third semiconductor layer;
a first electrode formed directly on the first semiconductor layer and electrically connected to the first semiconductor layer;
a second electrode electrically connected to the third semiconductor layer; and
a diffraction grating buried in the first low refractive index layer in a region below the active layer, wherein
a width of the third semiconductor layer, on the active layer side, in a width direction, which is perpendicular to a waveguide direction and parallel to a plane of the substrate, is smaller than a width of the active layer in the width direction.