Method of manufacturing semiconductor laser element by formation and removal of ridge part protrusion

A method of manufacturing a semiconductor laser element having a ridge part comprising a cladding layer, a capping layer and an intermediate layer therebetween, the method comprising:

• a laminating step of laminating a plurality of lamination layers on a semiconductor substrate in a laminating direction;
• a protruding step of forming, after the laminating step, the cladding layer, the capping layer, and a precursor of the intermediate layer so that widths of the cladding layer and the capping layer become shorter or uniform with the advance in the laminating direction, and the precursor of the intermediate layer protrudes widthwise from the cladding layer and the capping layer by at least 1.0 μm, the intermediate layer having a thickness from 0.02 μm to 0.05 μm;
• and
• a removing step of removing the protrusion of the precursor of the intermediate layer to form a compound semiconductor multilayer structure,
• wherein the precursor of the intermediate layer comprising a first removing region and a second removing region that is removed in the removing step in coordination with the first removing region.