Optical Device

An optical device comprising:

• a cladding layer;
• a core made of a compound semiconductor and formed on the cladding layer;
• an active layer embedded in an active region of the core;
• a first semiconductor layer made of an n-type compound semiconductor and a second semiconductor layer made of a p-type compound semiconductor, the first semiconductor layer and the second semiconductor layer being formed on the cladding layer, sandwiching the active region, and each being formed in contact with a side surface of the core;
• a third semiconductor layer made of an n-type compound semiconductor, formed on the cladding layer, being disposed so as to sandwich the first semiconductor layer with the active region, and connected to the first semiconductor layer;
• a fourth semiconductor layer made of a p-type compound semiconductor, formed on the cladding layer, being disposed so as to sandwich the second semiconductor layer with the active region, and connected to the second semiconductor layer;
• a first electrode connected to the third semiconductor layer;
• a second electrode connected to the fourth semiconductor layer;
• and
• a first passive optical waveguide and a second passive optical waveguide including the core in two regions sandwiching the active region and connected to the active region, wherein
• the first semiconductor layer includes a first region having a trapezoidal shape in which a width decreases from the core side toward the third semiconductor layer side in plan view and a first enlarged region having a trapezoidal shape in which a width increases from the first region side toward the third semiconductor layer side, and
• the second semiconductor layer includes a second region having a trapezoidal shape in which a width decreases from the core side toward the fourth semiconductor layer side in plan view and a second enlarged region having a trapezoidal shape in which a width increases from the second region side toward the fourth semiconductor layer side.