| 摘要 |
PROBLEM TO BE SOLVED: To provide a lateral optically coupled DFB layer which is excellent in laser characteristics and capable of restraining light from oozing out. SOLUTION: This DFB laser device 10 is equipped with a laminated structure formed on an N-InP substrate 12. The laminated structure is composed of an N-InP layer 14, an active layer 16, a P-InP layer 18A, a P-AlInAs oxidized layer 18B, a P-clad layer 20, a P-AlInAs oxidized layer 22, a P-clad layer 24, and a P-contact layer 26. The laminated structure above the active layer is formed like a stripe-like ridge. The InP layer 18aA is formed into a grating that is of periodic structure in the extending direction of the ridge. The Al oxidized layer 18B is formed on the grating. The Al oxidized layers are turned to Al oxide layers 28 and 30 in which Al is selectively oxidized except for center region of the ridge. The Al oxide layer 30 of the Al oxidized layer 22 serves as a current constriction layer. The Al oxidized layer 18B is turned into the Al oxide layer by oxidization, by which the refractive index of the Al oxide layer becomes small, and a refractive index difference between the InP layer and the Al oxide layer becomes small, so that the Al oxide layer is formed into a diffraction grating together with the InP layer.
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