| 摘要 |
PURPOSE:To improve oscillation spectral purity by forming a modulation region optically coupled with one of a laser region and an optical guide layer optically coupled with the other of an active layer and increasing the reflectivity of the emission end surface of the optical guide layer. CONSTITUTION:A diffraction grating 10 is shaped only on the surface of a section as a laser region 22 on an N-InP substrate l, and an N-InGaAsP optical guide layer 12, an InGaAsP active layer 13 and a P-InP clad layer 30 are grown. An SiO2 film is prepared so as to coat the whole surface on the layer 30 and patterned, the SiO2 film except the upper sections of the laser region 22 and a modulation region 23 is removed, and the P-InP layer 30 and the InGaAsP active layer 13 are etched selectively. An InGaAsP optical guide layer 50 is grown, the SiO2 film is etched, a P-InP clad layer 31 is grown on the layer 50 and flattened, and a P<+>-InGaAsP cap layer 20 is grown in an epitaxial manner in order. Accordingly, spectral purity is improved, the efficiency of frequency modulation is enhanced, and the frequency characteristics of the laser are flattened. |
