Patent ID: 7300217

Claim:
An optical semiconductor device, comprising: a lead frame having at least two through holes; at least one semiconductor optical element which has an optical portion and which is placed on one surface of the lead frame for the optical portion to face at least one of the through holes and overlap with the at least one of the through holes; a first molding portion which covers the semiconductor optical element and which is made of a non-transparent molding resin placed on one surface of the lead frame; and a second molding portion which covers the through hole and which is made of a transparent molding resin placed on the other surface of the lead frame, an expansion coefficient of the second molding portion being different from an expansion coefficient of the first molding portion, wherein wherein, the first molding portion and the second molding portion make contact with one another through at least one of the at least two through holes, and an area of a confronting surface of the second molding portion confronting the first molding portion is smaller than an area of a confronting surface of the first molding portion confronting the second molding portion.