| 摘要 |
PURPOSE:To stabilize an exial mode by making layer thickness on the channel outside of a clad layer close by the substrate side more than an active layer different from others only in a specific region along a waveguide and making a lateral effective refractive index difference in the region different from others. CONSTITUTION:A clad layer 2, an active layer 3, a clad layer 4 and a cap layer 5 are grown on a surface with a channel groove in a substrate 1 in an epitaxial manner in succession, thus forming double hetero-junction type laser operating multilayer crystal structure. The layer thickness of the clad layer 2 on the channel outside 9 is made thicker than a corresponding section 7 in a region as an internal reflection section. Beams propagated in a waveguide on the channel inside sense the change of an effective refractive index in B-B' region, and one part thereof is reflected in the B-B' region. Accordingly, the effective internal reflection section is constituted by giving distribution to a distance between the active layer and the substrate through a means such as the formation of longitudinal and lateral grooves of two kinds to the substrate, thus realizing the stability of an excellent axial mode by a simple interference type laser.
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