SEMICONDUCTOR OPTICAL DEVICE AND METHOD OF MANUFACTURING SEMICONDUCTOR OPTICAL DEVICE

A semiconductor optical device includes: a base configured to intersect with a first direction; a first protrusion configured to protrude from the base in the first direction, the first protrusion including a planar lightwave circuit including: a core layer; and a cladding layer surrounding the core layer; a second protrusion configured to protrude from the base in the first direction and arranged along the first protrusion in a second direction intersecting with the first direction, a height of the second protrusion from the base in the first direction being lower than a height of the first protrusion; an optical semiconductor element placed on a facet of the second protrusion in the first direction and optically connected to the core layer; and a marker provided on the second protrusion in a manner exposed on the facet, the marker being made of a same material as the core layer.