A mixing chamber includes a first surface and a second surface opposite the first surface. At least two light emitting diodes are disposed along the first surface. At least a portion of the first surface is reflective, and the second surface includes a reflective region and a plurality of openings formed in the reflective region. In some embodiments, the first surface and the second surface are separated by at least one side surface. Light emitted from the light emitting diodes is reflected off the first surface, reflective region of the second surface, and side surfaces of the mixing chamber until it is emitted from the openings of the second surface.