JPS6441291A - Semiconductor laser - Google Patents

Abstract

PURPOSE:To realize oscillation small in its threshold value and high in its efficiency and besides to realize large-output oscillation on a stable fundamental transverse mode, by providing a central part of a resonator with a guiding structure based on a distribution of a positive refractive index and optical absorption. CONSTITUTION:An n-type Al0.45Ga0.55As first clad layer 11 and an undoped Al0.15Ga0.85 As active layer 12 are formed on an n-type GaAs substrate 10. A p-type Al0.35Ga0.65As first guide layer 13, whose refractive index is larger than that of the first clad layer 11 and smaller than that of the active layer 12, is formed on the layer 12. An n-type GaAs first block layer 14 and an n-type Al0.5Ga0.5As second block layer 15, which have opposite conductivity types to what the guide layer 13 has and are smaller in their band gaps than said active layer 12, are formed serially on the first guide layer 13. A groove 16 is formed so that it attains to the first clad layer 11 on an end plane side of these block layers and attains to the first guide layer 13 at the central part of them. A third clad layer 21, whose refractive index is larger than those of the second clad layer 19, the second guide layer 20, and the second block layer 15, is buried into this groove 16. Further, a striped current injection means is installed above the groove 16.