| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor laser element in quantum well structure for making the sectional shape of a radiation beam nearly round and improving the connection efficiency with an optical fiber. SOLUTION: A quantum well layer 7 is formed nearly at the center of an InP substrate 1, and a constriction layer 8 is formed at both left and right sides. The quantum well layer 7 is composed by the lamination structure of an N-type clad layer 2, an optical confinement layer 23, an active layer 24, an optical confinement layer 25, and a P-type clad layer 6. The total of the thickness of the active layer 24, and the optical confinement layers 23 and 25 is set to 2,000Åor less, an optical confinement coefficient is reduced, the amount of exudation of light that is confined into the active layer 24 for activation to the side of the clad layers 2 and 6 is increased, and the expansion angle of the beam in a vertical direction that is radiated from the active layer 24 and the exudation part is reduced, thus outputting a beam in a pattern mode nearly close to a complete round.
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