An optical proximity sensor module includes a substrate, a light emitter mounted on a first surface of the substrate, the light emitter being operable to emit light at a first wavelength, and a light detector mounted on the first surface of the substrate, the light detector being operable to detect light at the first wavelength. The module includes an optics member disposed substantially parallel to the substrate, and a separation member disposed between the substrate and the optics member. The separation member may surround the light emitter and the light detector, and may include a wall portion that extends from the substrate to the optics member and that separates the light emitter and the light detector from one another. The separation member may be composed, for example, of a non-transparent polymer material containing a pigment, such as carbon black.