| 摘要 |
PURPOSE:To obtain an element characterized by no astigmatism and excellent noise characteristics, by changing the width of the forbidden band of the third clad layer, which is provided on a light absorbing layer, in comparison with the other region of a semiconductor laser. CONSTITUTION:On a GaAs substrate 1, the first double heterostructure, which comprises a first clad layer 2 of N-Ga0.65Al0.45As, an undoped Ga0.86Al0.14As active layer 3 and a second clad layer 4 of P-Ga0.65Al0.35As, is formed. Then the second double heterostructure, which comprises the clad layer 4 on the active layer 3, a P-GaAs light absorbing layer 5 and a third clad layer 5 of P-Ga0.6Al0.4As, is formed. The propagation factor of the second double heterostructure is made larger than that of the first double heterostructure formed by the active layer. The composition of the third clad layer 6 in the region in the vicinity of the end surface of a laser stripe is made different from that in the region in the element. Thus the difference in refractive indexes between the inside and outer edge part of the stripe at the end surface part can be made large, and that in the element can be made small.
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