| 摘要 |
PROBLEM TO BE SOLVED: To provide a semiconductor laser with Fabry-Perot mode oscillations suppressed, resulting in a large sub-mode suppression ratio (SMSR), and a semiconductor laser whose coupling coefficient is satisfactorily uniform, resulting in a high product yield. SOLUTION: A DFB laser 10 comprises a laminated structure, in which an InP buffer layer 14, an active layer 16, an InP spacer layer 18 with a film thickness of 200 nm, a diffraction grating 20 consisting of a GaInAsP layer and having a periodic of 240 nm and a film thickness of 20 nm, and an InP first clad layer 22, in which the diffraction grating is embedded, are sequentially formed on an InP substrate 12. The peak wavelengthλ<SB>max</SB>in the optical gain distribution of the active layer is approximately 1,530 nm, and the bandgap wavelength of the diffraction grating is approximately 1,510 nm. By forming the diffraction grating of GaInAsP havingλ<SB>g</SB>of approximately 1,510 nm, absorption hardly takes place at the oscillation wavelength close to 1,550 nm. The absorption coefficient for the peak wavelength in the optical gain distribution of the active layer is larger than the absorption coefficient for the oscillation wavelength. COPYRIGHT: (C)2006,JPO&NCIPI
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