Optical semiconductor device and circuit

An optical semiconductor device comprising:

• a light-emitting element;
• a lead frame having a concave portion and a pair of electrode terminals, the concave portion configured for mounting the light-emitting element therein and having a first light emitting direction and an opposite rearward direction, the concave portion having a bottom portion that is located furthest in the rearward direction as compared to other portions of the concave portion;
• and
• a sealing resin portion located adjacent a region of the concave portion, wherein
• the bottom portion of the concave portion is located a distance from a plane that intersects the pair of electrode terminals such that the bottom portion is configured to be at a predetermined distance from a connecting surface on which the pair of electrode terminals are configured to be connected, and at least a portion of the bottom portion of the concave portion is exposed from a bottom surface of the sealing resin portion.