Apparatuses and methods to sense proximity and to detect light. In one embodiment, an apparatus includes an emitter of electromagnetic radiation and a detector of electromagnetic radiation; the detector has a sensor to detect electromagnetic radiation from the emitter when sensing proximity, and to detect electromagnetic radiation from a source other than the emitter when sensing visible light. The emitter may be disabled at least temporarily to allow the detector to detect electromagnetic radiation from a source other than the emitter, such as ambient light. In one implementation, the ambient light is measured by measuring infrared wavelengths. Also a fence having a non-IR transmissive material disposed between the emitter and the detector to remove electromagnetic radiation emitted by the emitter. Other apparatuses and methods and data processing systems and machine readable media are also described.