Semiconductor optical integrated device

Patent metadata

Field	Value
Publication number	US-11215774-B2
Application number	US-201816959356-A
Country	US
Kind code	B2
Filing date	Feb 19, 2018
Priority date	Feb 19, 2018
Publication date	Jan 4, 2022
Grant date	Jan 4, 2022

Abstract

A semiconductor optical integrated device is a semiconductor optical integrated device in which a first optical element, a monitoring light waveguide and a second optical element, through which light propagates, are formed on a common semiconductor substrate; wherein the monitoring light waveguide is joined to the first optical element, and the second optical element is joined to the monitoring light waveguide. The monitoring light waveguide includes a light scattering portion for scattering a part of the light, which is composed of a combination of light waveguides having different mode field diameters or having different centers of mode field diameters; and a light detector for receiving scattered light scattered by the light scattering portion, is placed on an outer periphery of the monitoring light waveguide, or on a back surface of the semiconductor substrate on its side opposite to that facing the light scattering portion.

First claim

The invention claimed is:

1. A semiconductor optical integrated device in which a first optical element, a monitoring light waveguide and a second optical element, through which light propagates, are formed on a common semiconductor substrate;
wherein the monitoring light waveguide is joined to the first optical element, and the second optical element is joined to the monitoring light waveguide;
wherein the monitoring light waveguide comprises a layered body which is formed on the semiconductor substrate and in which a first cladding layer, a light waveguide layer having a light scattering portion for scattering a part of the light, and a second cladding layer, are successively stacked;
wherein the layered body has:
a high-mesa structure provided with a pair of mesa facets which are opposite to each other in an X-direction perpendicular both to a Y-direction that is perpendicular to the semiconductor substrate, and to a Z-direction that is a propagating direction of the light, and on which the light waveguide layer is exposed; or
a buried structure provided with a pair of mesa facets which are opposite to each other in the X-direction perpendicular both to the Y-direction that is perpendicular to the semiconductor substrate, and to the Z-direction that is the propagating direction of the light, and on which the light waveguide layer is not exposed;
wherein the light scattering portion is composed of a combination of light waveguides having different mode field diameters, or a combination of light waveguides that are joined to each other in a state in which centers of the mode field diameters of the respective light waveguides are displaced from each other;
wherein a light detector for receiving scattered light scattered by the light scattering portion, is placed on a placement surface that is a surface of the monitoring light waveguide on its side opposite to that facing the semiconductor substrate, or that is the mesa facet; and
wherein a distance from the light waveguide layer to the placement surface on which the light detector is placed, is such a distance that is larger than a mode field diameter of the light propagating through the light waveguide layer, and that does not allow an evanescent component of the light propagating through the light waveguide layer, to be caught in the light detector.

2. The semiconductor optical integrated device of claim 1 , wherein the light scattering portion is a mode-field-diameter varying portion which is established due to partial variation in refractive index of the light waveguide layer.

3. The semiconductor optical integrated device of claim 1 , wherein the monitoring light waveguide comprises a first light waveguide and a second light waveguide having different mode field diameters and different waveguide modes for the light, and a mode-conversion light waveguide for performing waveguide-mode conversion for the light, said mode-conversion light waveguide being connected between the first light waveguide and the second light waveguide; and
wherein the mode-conversion light waveguide is the light scattering portion.

4. The semiconductor optical integrated device of claim 1 , wherein the monitoring light waveguide comprises a first light waveguide and a second light waveguide having different mode field diameters; and
wherein the light scattering portion is a butt joint portion where the first light waveguide and the second light waveguide are joined to each other through a butt joint in a state in which centers of the mode field diameters of the respective light waveguides are displaced from or coincide with each other.

5. The semiconductor optical integrated device of claim 1 , wherein the monitoring light waveguide comprises a first light waveguide and a second light waveguide having same mode field diameters; and
wherein the light scattering portion is a butt joint portion where the first light waveguide and the second light waveguide are joined to each other through a butt joint in a state in which centers of the mode field diameters of the respective light waveguides are displaced from each other.

6. A semiconductor optical integrated device in which a first optical element, a monitoring light waveguide and a second optical element, through which light propagates, are formed on a common semiconductor substrate;
wherein the monitoring light waveguide is joined to the first optical element, and the second optical element is joined to the monitoring light waveguide;
wherein the monitoring light waveguide comprises a layered body which is formed on the semiconductor substrate and in which a first cladding layer, a light waveguide layer having a light scattering portion for scattering a part of the light, and a second cladding layer, are successively stacked;
wherein the layered body has:
a high-mesa structure provided with a pair of mesa facets which are opposite to each other in an X-direction perpendicular both to a Y-direction that is perpendicular to the semiconductor substrate, and to a Z-direction that is a propagating direction of the light, and on which the light waveguide layer is exposed; or
a buried structure provided with a pair of mesa facets which are opposite to each other in the X-direction perpendicular both to the Y-direction that is perpendicular to the semiconductor substrate, and to the Z-direction that is the propagating direction of the light, and on which the light waveguide layer is not exposed;
wherein the light scattering portion is a bent portion formed in the light waveguide layer;
wherein a light detector for receiving scattered light scattered by the light scattering portion, is placed on a placement surface that is a surface of the monitoring light waveguide on its side opposite to that facing the semiconductor substrate; and
wherein a distance from the light waveguide layer to the placement surface on which the light detector is placed, is such a distance that is larger than a mode field diameter of the light propagating through the light waveguide layer, and that does not allow an evanescent component of the light propagating through the light waveguide layer, to be caught in the light detector.

7. A semiconductor optical integrated device in which a first optical element, a monitoring light waveguide and a second optical element, through which light propagates, are formed on a common semiconductor substrate;
wherein the monitoring light waveguide is joined to the first optical element, and the second optical element is joined to the monitoring light waveguide;
wherein the monitoring light waveguide comprises a layered body which is formed on the semiconductor substrate and in which a first cladding layer, a light waveguide layer and a second cladding layer are successively stacked;
wherein the layered body has a buried structure provided with a pair of mesa facets which are opposite to each other in an X-direction perpendicular both to a Y-direction that is perpendicular to the semiconductor substrate, and to a Z-direction that is a propagating direction of the light, and on which the light waveguide layer is not exposed;
wherein the monitoring light waveguide has, on at least one of the mesa facets across the X-direction, a concave portion in which a tail of a distribution of the light is caught;
wherein the concave portion serves as a light scattering portion for scattering a part of the light;
wherein a light detector for receiving scattered light scattered by the light scattering portion, is placed on a placement surface that is a surface of the monitoring light waveguide on its side opposite to that facing the semiconductor substrate, or that is one of the mesa facets, provided that it does not have said concave portion; and
wherein a distance from the light waveguide layer

Assignees

• Mitsubishi Electric Corp

Inventors

• Nakamura Naoki
• Ishimura Eitaro

Classifications

• H10F77/413

  directly associated or integrated with the devices, e.g. back reflectors (directly associated or integrated with photovoltaic cells H10F77/42) · CPC title

• H10F30/21

  the devices being sensitive to infrared, visible or ultraviolet radiation · CPC title

• H01S5/1003

  Waveguide having a modified shape along the axis, e.g. branched, curved, tapered, voids · CPC title

• H01S5/026

  Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers (stabilisation of output H01S5/06) · CPC title

• G02B6/1228

  Tapered waveguides, e.g. integrated spot-size transformers (for coupling with fibres G02B6/305) · CPC title