An optical proximity sensor is provided that comprises an infrared light emitter, an infrared light detector, a ceramic housing, a substrate, and a cover or shield. The ceramic housing is mounted on or attached to the substrate, and comprises first and second recesses separated by a light barrier. The cover is mounted over the ceramic housing, the light emitter and the light detector. The infrared light emitter is located within the first recess and mounted on the substrate. The infrared light detector is located within the second recess and mounted on the substrate. The light barrier between the first and second recesses, in conjunction with the remainder of the ceramic housing, the substrate, and the cover or shield substantially attenuates or blocks the transmission of undesired direct, scattered or reflected infrared light between the light emitter and the light detector, and thereby minimizes optical crosstalk and interference between the light emitter and the light detector.