Method for manufacturing optical semiconductor waveguide window structure

A method for manufacturing a semiconductor light source element, the method comprising:

• forming an active layer on an InP substrate, wherein the active layer is a crystal grown layer and wherein a crystal orientation of a surface thereof was a (1 0 0) plane and an orientation flat thereof was a (0 −1 −1) plane;
• forming a first etching mask on the active layer, and removing a part of the active layer, wherein a remaining part of the active layer is perpendicular to the orientation flat;
• forming an EA (Electro-Absorption) layer, wherein the EA layer is a crystal grown layer and wherein the EA layer forms a core layer of an EA modulator, without removing the first etching mask;
• removing the first etching mask and forming a second etching mask on the active layer;
• partially removing the EA layer, such that a region serving as a window structure remains, wherein the region remaining is wider than a mesa stripe;
• removing the second etching mask and then forming the window structure by forming an overclad layer on an entire surface;
• and
• forming a third etching mask on the overclad layer, and then forming the mesa stripe by removing each of the overclad layer, the active layer, the EA layer, and a part of the InP substrate, wherein the mesa strip has a height of at least 3 μm.