| 摘要 |
PURPOSE:To improve the yield of an element operating at a single mode by narrowing the width of a striped active layer near a section where the periodicity of a diffraction grating shifts. CONSTITUTION:A diffraction grating 10 and phase shifting sections 11 inverting the periodicity of the irregularities of the grating 10 in the left and right regions are formed on the surface of an N-InP substrate 1. An N-InGaAsP guide layer 2, a non-doped N-InGaAsP active layer 3, a P-InGaAsP anti-melt-back layer 4 and a P-InP clad layer 5 are grown in an epitaxial manner. Two parallel grooves 12 deeper than the active layer 3 are shaped on a multilayer semiconductor crystal acquired and a mesa stripe 13 between the parallel grooves 12. The width of the stripe 13 is brought to 1.5mum where far from sections such as the phase shifting sections 11 and to 1.0mum in the phase shifting sections 11 at that time, and the stripe 13 takes a constricted shape in the phase shifting sections 11. Accordingly, oscillation at a stable single axial mode can be obtained. |
