Semiconductor laser device having a transparent waveguide and a large second harmonic generation output

A semiconductor laser device comprising;

• a semiconductor laser having a semiconductor substrate, a first cladding layer, an active layer, a second cladding layer, an electrode disposed on at least an upper surface of said second cladding layer and a cavity comprising said first and second cladding layers and said active layer, for oscillating a fundamental wave;
• and
• a transparent waveguide disposed on said semiconductor laser substantially in parallel to a length direction of said cavity wherein,
• when a refractive index of the fundamental wave is made .lambda., a refractive index of said active layer with respect to the fundamental wave is made n.sub.i (.lambda.), a refractive index of said transparent waveguide with respect to the fundamental wave is made n.sub.2 (.lambda.), and an effective refractive index of the optical waveguide constituted by said semiconductor laser and said transparent waveguide is made n.sub.2, it follows that
• n.sub.2 (.lambda.)<n.sub.1 (.lambda.)
• n.sub.2 <n.sub.2 (.lambda./2)
• thereby second harmonics of the fundamental wave travel through said transparent waveguide and are emitted therefrom.