Method of producing multi-wavelength semiconductor laser device

A method for producing a multi-wavelength semiconductor laser device, comprising the steps of:

• preparing a substrate for growth of a nitride single crystal thereon;
• sequentially growing a first conductivity-type first clad layer, a first active layer and a second conductivity-type first clad layer on the substrate, to form a nitride epitaxial layer;
• separating the nitride epitaxial layer from the substrate;
• attaching the separated nitride epitaxial layer to a first conductivity-type substrate;
• selectively removing the nitride epitaxial layer such that a portion of the substrate is exposed, to form a first semiconductor laser structure;
• sequentially growing a first conductivity-type second clad layer, a second active layer and a second conductivity-type second clad layer on the exposed portion of the first conductivity-type substrate, to form a second semiconductor laser structure separated from the first semiconductor laser structure;
• sequentially growing a first conductivity-type third clad layer, a third active layer and a second conductivity-type third clad layer on the remaining portion of the first conductivity-type substrate, to form a third semiconductor laser structure separated from the first and second semiconductor laser structures;
• and
• forming a first electrode connected to a bottom surface of the first conductivity-type substrate and forming second electrodes connected to the respective second conductivity-type clad layers of the first, second and third semiconductor laser structures.