Semiconductor lasers and method for producing the same

Claim 1

A semiconductor laser having cleavage planes, comprising: a compound single crystalline semiconductor substrate; a current-blocking multilayer, formed on said compound single crystalline semiconductor substrate, having an upper layer and a lower layer forming a reverse-biased PN junction, said compound single crystalline semiconductor substrate and said multilayer having a groove formed therein, extending from the upper layer of said multilayer into said compound single crystalline semiconductor substrate, recesses formed in the sides of said groove by selectively etching said lower layer; a lower clad layer, embedded in said groove, extending from the bottom of said groove to a lower edge of said recesses; a stripe active layer formed on said lower clad layer, having an upper plane and a lower plane, and having sides inclined toward said upper and lower planes, said upper and lower planes being substantially parallel to each other; an upper clad layer formed on said stripe active layer and said multilayer so as to fill said groove, said lower and upper clad layers surrounding said stripe active layer; and electrode layers formed on said compound single crystalline semiconductor substrate and said upper clad layers, respectively.