| 摘要 |
PURPOSE:To improve single axial-mode oscillation probability, to simplify the manufacture of said oscillation probability and to facilitate development to a surface emission type DFB (a distributed feedback type semiconductor) laser by forming one part of periodical irregular structure along the progressive direction of light in the irregular structure of a double period. CONSTITUTION:A primary diffraction grating 4 is shaped onto an InP substrate 1 having the crystal orientation of (100), a resist for protection is formed only to the section of the primary diffraction grating 4, and a secondary diffraction grating 5 having a double period is shaped continuously to a residual section through the same method. An N-InxGa1-xAsyP1-y optical guide layer 6, an undoped InxGa1-xAsyP1-y active layer 7 corresponding to an emission wavelength of 1.55mum, a P-InP clad layer 8 and a P-InxGa1-xAsyP1-y cap layer 9 are grown successively onto the diffraction gratings 4, 5, a stripe is shaped onto the layer 9 by an SiO2 film 10 for confining currents, and a P-type electrode 11 and an N-type electrode 12 are formed. Since the coupling coefficient of the region I of the grating 4 is made larger than that of the region II of the grating 5, regeneration between two longitudinal modes is removed, gain difference is generated, and single mode oscillation probability is improved, thus acquiring a DFB laser having a high sub-mode suppression ratio. |
