Optical integrated device and manufacturing method of the same

A method of manufacturing an optical integrated device, the method comprising:

• forming a lower clad layer on a substrate;
• forming a plurality of mask patterns arranged in a first direction on the lower clad layer;
• forming core layers on a portion of the lower clad layer by a selective area growth method using the mask patterns as deposition masks;
• and
• forming an upper clad layer on the core layers,
• wherein the mask patterns have different widths in a second direction intersecting the first direction or comprise mask layers of different materials, and
• wherein the mask patterns comprise:
• first mask patterns having a first pattern width and having a central opening width partially exposing the lower clad layer;
• and
• second mask patterns having a second pattern width less than the first pattern width and having the central opening width adjacent to one side of the first mask patterns.