PHOTOSEMICONDUCTOR DEVICE

PURPOSE:To obtain excellent optical coupling without any optical axis adjustment at the time of the assembly of an optical module, to facilitate mounting operation, and to provide the photosemiconductor device which is superior in mass-productivity by fixing a spherical lens and a photosemiconductor element by using a silicon substrate where a square V-grooved through hole is formed. CONSTITUTION:A square opening part and a through hole having a flank at a certain angle determined by the crystal azimuth of a silicon substrate 11 are formed in the silicon substrate 11 by anisotropic etching; and the spherical lens 12 is fixed in contact with the flank of the through hole and the photosemiconductor element 13 is fixed on the other surface of the silicon substrate 11 so that its light emission or reception surface faces the spherical lens 12 through the small-diameter opening part.