MANUFACTURE OF SINGLE AXIAL MODE LASER

摘要

PURPOSE:To reduce the deformation of a diffraction grating by melting back and to enable preserving the deep diffraction grating by liquid phase epitaxy in a state that the surface on which the diffraction grating is formed is partially covered. CONSTITUTION:In the case of an InGaAsP/InP system DFB-LD, a diffraction grating 7 is formed on the surface of an optical waveguide layer 4 after an n<+>-InP buffer layer 2, an InGaAsP active layer 3 and an InGaAsP optical waveguide layer 4 are grown by LPE on an n<+>-InP substrate 1. An SiO2 film 8 is deposited on the diffraction grating 7 for covering the grating by leaving a stripe W wide in the direction perpendicular to the pattern of the diffraction grating. A p-InP is grown by LPE on the diffraction grating on which the SiO2 film 8 is partially formed. A solute on the SiO2 film 8 is concentrated in the aperture 11 of the SiO2 film 8 as shown by an arrow 10 by the existence of the SiO2 film 8 and the melting back of the exposed diffraction grating can be restrained by the effective increase of the supersaturation in the aperture.