A receiver assembly (100) and data communications method are disclosed. In one arrangement, a receiver assembly (100) comprises a concentration stage (14). The concentration stage (14) receives radiation via an input surface (120) and outputs concentrated radiation via an output surface (122). The concentration stage comprises a wavelength converting member (6) that converts radiation to longer wavelength radiation. An optical element (102) is provided which is such that if a plane wave of radiation is incident on the optical element a spatial distribution of radiation derived from the plane wave on the input surface of the concentration stage varies as a function of a direction of incidence of the plane wave relative to the optical element. A plurality of detectors (42) are provided, each detecting radiation output from a different portion of the output surface of the concentration stage.