Semiconductor optical integrated device

A semiconductor optical integrated device, comprising:

• a first semiconductor mesa portion, having an active layer containing a group III-V semiconductor, and extending in a prescribed axial direction;
• a second semiconductor mesa portion, having an active layer containing a group III-V semiconductor, optically coupled with said first semiconductor mesa portion, and extending in a prescribed axial direction;
• a first conductivity type group III-V semiconductor layer which is provided on said first and second semiconductor mesa portions, is separated into a first region for a light-emitting element portion, a third region for a modulation element portion and a second region for a separation portion separating said light-emitting portion and said modulation element portion, and has a depression portion in said second region;
• a first electrode, provided on said first region of said group III-V semiconductor layer, and a second electrode, provided on said third region of said group III-V semiconductor layer;
• and,
• a group III-V semiconductor portion, of a second conductivity type differing from said first conductivity type, provided in said depression portion.