Semiconductor optical device, optical module, and manufacturing method of semiconductor optical device

A method of manufacturing a semiconductor optical device comprising:

• preparing an element structure layer including a mesa stripe extending in a first direction;
• forming a conductive layer on an upper surface of the element structure layer;
• and
• separating the conductive layer to form:
• an electrode film that covers at least an upper surface of the mesa stripe,
• an electrode pad portion that covers a part of a first region positioned in a second direction, intersecting the first direction, relative to the mesa stripe on an upper surface of the element structure layer and is electrically connected to the electrode film,
• a first dummy electrode that covers another part of the first region and is electrically insulated from the electrode film, and
• a second dummy electrode that covers at least a part of a second region positioned in a third direction, opposite to the second direction, relative to the mesa stripe on the upper surface of the element structure layer and is electrically insulated from the electrode film,
• wherein, in the separating the conductive layer, the first dummy electrode includes a first portion disposed in the first direction relative to the electrode pad portion and a second portion disposed in a fourth direction, opposite to the first direction, relative to the electrode pad portion.