Method of making semiconductor laser with inverted mesa shaped ridge with cervical surface

A method of producing a semiconductor laser comprising the steps of forming at least a first conduction type clad layer, an active layer and a second conduction type clad layer on a first conduction type semiconductor substrate in this order, selectively forming insulating film in a striped pattern on the second conduction type clad layer, forming an inverted mesa-shaped ridge by etching a part of the second conduction type clad layer using the insulating film as a mask and forming a first conduction type current stopping layer on each side of the ridge, wherein the improvement comprising

• the step of curving each side of the inverted mesa-shaped ridge into a concave surface in a plane perpendicular to the longitudinal direction of the ridge.