The disclosed subject matter relates to communicatively coupled cognitive radio systems, devices, methodologies, or combinations thereof, facilitating improved utilization of unused portions of spectral bands by secondary users generally allocated to other primary users. The diffraction grating, after having been subjected to a test condition of 85 degrees centigrade and a relative humidity of 85 percent for at least 500 hours, has diffraction efficiency performance within 6 percent of that achieved before being subjected to these test conditions. The primary colors of the display device can be selected in a time sequential and space sequential way which enable a reduction of a color break-up.