OPTICAL SEMICONDUCTOR DEVICE AND WAVELENGTH VARIABLE LIGHT SOURCE USING THE SAME AND OPTICAL TOMOGRAPHIC IMAGE ACQUIRING APPARATUS

PROBLEM TO BE SOLVED: To provide an optical semiconductor device which is easily manufactured and has a wide band gain spectral width. SOLUTION: In this optical semiconductor device 10 wherein the resonance of light within the device is suppressed and at least an InGaP lower clad layer and an InGaAs active layer are laminated on an n-GaAs substrate 11, the n-GaAs substrate, whose plane orientation being inclined by an angle of not less than three degrees and not more than ten degrees, e.g., three degrees, in the dorection from (111) B plane to (100) plane, is used as the n-GaAs substrate 11. The step bunching of the InGaP lower clad layer is formed, and variation arises in the layer thickness of the InGaAs active layer. COPYRIGHT: (C)2009,JPO&INPIT