Semiconductor optical device and optical transceiver module

An optical transceiver module, comprising:

• a transmitter optical subassembly for outputting optical signals converted from input electric signals;
• and
• a receiver optical subassembly for outputting electric signals converted from input optical signals,
• wherein the transmitter optical subassembly comprises a semiconductor optical device comprising:
• a semiconductor substrate with a projection in a stripe shape extending in a first direction,
• the projection constituting at least a first portion of a mesa stripe structure;
• a quantum well layer in the stripe shape extending in the first direction and on the projection,
• the quantum well layer constituting a second portion of the mesa stripe structure;
• and
• a buried layer, adjacent to both sides of the mesa stripe structure in a second direction perpendicular to the first direction, on an upper surface of the semiconductor substrate,
• wherein:
• the upper surface of the semiconductor substrate has a first slope descending from the projection in the second direction at an angle of 0-12° respective to a horizontal plane,
• the mesa stripe structure has an inclined surface with a second slope ascending from the upper surface of the semiconductor substrate at an angle of 45-55° respective to the horizontal plane,
• the mesa stripe structure has an upright surface rising from the inclined surface at an angle of 85-95° respective to the horizontal plane,
• the buried layer is made from a semiconductor with ruthenium doped therein and is in contact with the inclined surface and the upright surface,
• a height of the inclined surface is 80% or less of a height from the upper surface of the semiconductor substrate to a lower surface of the quantum well layer,
• the height of the inclined surface is 0.3 μm or more, and
• an area of the mesa stripe structure defined by a plane of the upper surface of the semiconductor substrate, a plane of the inclined surface, and a plane of the upright surface is recrystallized structure.

A method of manufacturing a semiconductor optical device, comprising:

• forming a mesa stripe structure, the mesa stripe structure comprising:
• a projection extending from a semiconductor substrate in a first direction,
• wherein an upper surface of the semiconductor substrate has a first slope descending from the projection at an angle of 0-12° respective to a horizontal plane, and
• a quantum well layer extending in the first direction and on the projection,
• wherein the mesa stripe structure has an upright surface at an angle of 85-95° respective to the horizontal plane;
• forming an inclined surface, of the mesa stripe structure, with a second slope ascending from the upper surface of the semiconductor substrate at an angle of 45-55° respective to the horizontal plane,
• wherein an area of the mesa stripe structure defined by a plane of the upper surface of the semiconductor substrate, a plane of the inclined surface, and a plane of the upright surface is recrystallized structure;
• and
• forming a buried layer, adjacent to both sides of the mesa stripe structure in a second direction perpendicular to the first direction, on the upper surface of the semiconductor substrate,
• wherein the buried layer is in contact with the inclined surface and the upright surface.