Semiconductor optical device having distributed feed-back type laser and electroabsorption-type modulator

A semiconductor optical device in which a light emitting region that emits light and a modulator region that modulates the light are integrated, the semiconductor optical device comprising:

• a first mesa that is disposed in the light emitting region, extends in a light propagation direction in which the light propagates, protrudes in a first direction intersecting the light propagation direction, and includes an active layer;
• a first buried layer and a second buried layer that are disposed on each of two sides of the first mesa in a second direction intersecting the light propagation direction and are sequentially stacked in the first direction;
• a first semiconductor layer that is disposed on the first mesa and the second buried layer;
• a second mesa that is disposed in the modulator region, extends in the light propagation direction, protrudes in the first direction, and includes a light absorption layer;
• a third buried layer that is disposed on each of two sides of the second mesa;
• and
• a resin layer that is disposed on each of the two sides of the second mesa and outside of the third buried layer,
• wherein the first semiconductor layer and the first buried layer each have a first conductivity type,
• wherein the second buried layer has a second conductivity type different from the first conductivity type, and
• wherein the third buried layer is a semi-insulating semiconductor layer.