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US 12,658,677 B2Granted
Opto-electronic device
AssigneeNokia Solutions and Networks Oy
InventorsAlexandre Garreau, Jean Francois Paret, Quentin Hochart
Life of this patent
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Abstract
The present invention concerns an optoelectronic device D such as a Semiconductor optical amplifier (SOA) working in a continuous wave condition and able to amplify high frequencies optical signals. The optoelectronic device D comprise an active zone I (such as SOA) with a slab (3) in a direct bias working in a continuous wave and a taper zone (II) connected to the active zone (I).
Claims16
Semiconductor optical device comprising:
- a substrate of n-doped III-V semiconductor material with a longitudinal axis and presenting a base with a planar bottom surface and an upper surface and side walls that are perpendicular to said base,
- said substrate including a central longitudinal cavity of U-shaped cross-section, whose width α and height d from the planar bottom surface vary along said longitudinal axis, so as to define at least 2 zones along said longitudinal axis delimited by a first junction,
- a first active zone, wherein the bottom surface and the upper surface of the base are parallel to each other and spaced from each other by a constant height d=d1, and the central longitudinal cavity presents a constant width α=α1,
- a second zone constituting a first taper zone, wherein the upper surface describes a continuous curved or planar surface comprising two opposite ends perpendicular to the longitudinal axis, one of the ends, being located at a height d1 at the first junction which is lower than the height d0 at the free end of the first taper zone, the width α varying from α1 at the first junction to α0 at the free end of the first taper zone,
- a layer of n-doped III-V semi-conductor material positioned on the upper surface of the base inside the cavity;
- a layer of n-inactive III-V optical waveguide material positioned on the layer of n-doped III-V semi-conductor material inside said cavity, said layer of n-inactive III-V optical waveguide material having an inverted T shape in a cross-section perpendicular to the longitudinal axis, so as to form a slab with a bottom of thickness e and an edge of thickness g, with e being constant and equal to e1 within the first active zone and varying within the first taper zone from e1 at the first junction to 0 at the free end of the first taper zone, and with g being constant and equal to g1 in the first active zone and varying within the first taper zone from g1 at the first junction to 0 at the free end of the first taper zone;
- said semiconductor optical device further comprising,
- a central ribbon having a width b and comprising, on the edge of the slab, a buried optical waveguide (4) beneath a layer of p-doped III-V semi-conductor,
- a pair of channels into the n-inactive III-V optical waveguide along the longitudinal axis and being located on both sides of the central ribbon, said longitudinal channels being each filled by a semi-insulating stack or an insulating stack, said channels being longitudinal and parallel to each other and of constant width W1 within the first active zone,
- within the first active zone, metal stripes covering the top of each sidewall and a metal stripe covering the top of the layer of p-doped III-V semi-conductor.
7 more elements
Method of fabricating a semiconductor optical device comprising:
- A) providing a substrate material made of n-doped III-V semiconductor material with a longitudinal axis, and presenting a bottom surface and a top surface;
- B) etching said substrate material so as to form a substrate having a base with a planar bottom surface and an upper surface, side walls perpendicular to said base, and a central longitudinal cavity of U-shaped cross-section, the height d of the upper surface from the planar bottom surface being constant and equal to d1 along the first active zone and varying from d1 at the junction to d0 at the free end of the first taper zone, with d0 greater than d1;
- C) performing an epitaxial growth of a layer of n-doped III-V semi-conductor and a layer of n-inactive III-V material stack of thickness h to fill the cavity;
- D) selectively etching the layer of n-inactive III-V material stack so that it defines a slope from the free end of the first taper zones down to the first junction, with the height h varying along the first taper zone, from the first junction down to 0 at the free end of the first taper zone;
- E) performing, on the layer of n-inactive III-V material stack inside the cavity, an epitaxial growth an active III-V material stack;
- F) performing, on said active III-V material stack inside the cavity, an epitaxial growth of a layer of p-doped III-V semi-conductor up to at least the level of the top of the side walls;
- G) removing the remaining portions of the first dielectric layer;
- H) selectively etching, into the n-inactive III-V optical waveguide and along the longitudinal axis, a pair of channels, each located along each side wall so as to define a central ribbon comprising,
- the layer of n-inactive III-V optical waveguide having an inverted T shape in a cross-section perpendicular to the longitudinal axis, so as to form a slab with a bottom of thickness e and an edge of thickness g, with e being constant and equal to e1 within the first active zone and varying within the first taper zone from e1 at the first junction to 0 at the free end of zone, with g being constant and equal to g1 in the first active zone and varying within the first taper zone from g1 at the first junction to 0 at the free end of the first taper zone;
- the etched active material stack constituting an active optical guide, and
- the etched layer of p-doped III-V semi-conductor material;
- I) inside the channels, performing regrowth of an insulating or semi-insulating stack up to at least the level of the top of the layer of p-doped III-V semi-conductor material;
- J) depositing, along said longitudinal axis, metal stripes on the top of the side walls and on the top of the central ribbon.
10 more elements
Dependencies are inferred from the claim text.