Abstract: In certain embodiments, a semiconductor package includes a leadframe, a light emitter die disposed on the leadframe, and a light detector die disposed on the leadframe adjacent to the light emitter die. In some embodiments, a first transparent molding compound is disposed over the light emitter die and a second transparent molding compound is disposed over the light detector die. The first and second transparent molding compound may be disposed such that a space between them forms a cavity between the die and above the leadframe. In other embodiments a transparent molding compound is disposed simultaneously over the light emitter and light detector die and a subsequent material removal process forms a cavity within the compound between the die. In both embodiments, an opaque molding compound is disposed in the cavity between the die, and is configured to block optical cross-talk between the light emitter and light detector die.