Patent ID: 8238397

Claim:
A semiconductor laser device comprising: an n-type GaAs substrate having a band gap energy and opposed first and second sides; an active layer supported by and at the first side of said GaAs substrate; first and second cladding layers sandwiching said active layer, wherein said first cladding layer is located between said active layer and said GaAs substrate; a first electrode disposed on the second side of said GaAs substrate; and a second electrode in electrical communication with said active layer through said second cladding layer, wherein each of said active layer, said first and second cladding layers, and said GaAs substrate has end surfaces at opposed first and second end surfaces of said semiconductor laser device, said first and second electrodes are transverse to said first and second end surfaces, laser light having an energy is generated in said active layer in response to an electrical current flowing between said first and second electrodes, the laser light resonates between said first and second end surfaces and between said first and second electrodes, the energy of the laser light generated is smaller than the band gap energy of said GaAs substrate, and said GaAs substrate has a charge carrier concentration of at least 2.2×10 18 cm −3 so that resonance of the laser light between said first and second electrodes is suppressed.