Fig. 1. XRD patterns of glass substrate, β-SiAlON∶Eu²⁺ phosphor and β-SiAlON-PiG-on-CSP

Fig. 2. SEM observation on β-SiAlON-PiG-on-CSP

Fig. 3. (a) Photoluminescence (PL) and PL excitation (PLE) spectra and (b) luminescent decay curves of β-SiAlON∶Eu²⁺ phosphor and β-SiAlON-PiG-on-CSP

Fig. 4. Luminescence behaviors under blue laser excitation. (a) Comparison of luminescence spectra of β-SiAlON-PiG-on-CSP and β-SiAlON-PiG-on-SP under 1 W/mm² laser excitation; (b) schematic illustration of β-SiAlON-PiG-on-CSP configuration structure, and comparison for actual lighting effects between samples with/without photonic crystal film (direction of incident blue laser comes from right to left); (c) variations in luminescence spectra of β-SiAlON-PiG-on-CSP sample versus incident laser power; (d) corresponding dependences of converted green light power and surface temperature on incident laser power density; inset shows infrared thermal image of β-SiAlON-PiG-on-CSP under 9 W/mm² laser excitation

Fig. 5. Exploring mechanism of luminescence saturation. (a) Dependences of relative conversion efficiency and absorption efficiency on incident laser power density; (b) integrated PL intensity of β-SiAlON-PiG-on-CSP versus temperature; (c) schematical illustration of optical saturation mechanism of ESA and ETU

Fig. 6. Performance after coupling red laser. (a) Electroluminescence spectra under 9 W/mm² blue laser irradiation; (b) corresponding CIE color coordinate diagram, including NTSC standard color gamut and prototype light source color gamut