| Abstract: | Solid state white light source where white light is generated by exciting phosphors using blue LEDs and lasers form most power efficient sources. To achieve long lifetime and stable sources capable of high-brightness lighting requires use of phosphor composites with high thermal conductivity. Using glass as a host matrix for phosphors is a good solution for creating phosphor in glass (PiG) composites. This thesis demonstrates a rapid fabrication process for surface type PiGs using YAG:Ce phosphor and borosilicate glass on glass wafer using CO2 laser sintering. It expedites the fabrication process and causes minimal degradation of phosphors during fabrication. This process is easily scalable and adaptable to variety of glass and phosphor material systems. Three different types of phosphor and glass stack configurations are demonstrated. With different phosphor content bright white light with CCT of 8100K to soft white light with CCT of 4000K is obtained. It shows maximum luminous efficacy of 113.2 lm/W which is comparable to the best white light sources. The samples show excellent color uniformity, with maximum difference in CCT of 461K compared to 1200K for phosphor in silicone (PiS) samples. To achieve high CRI, PiG composite consisting of YAG:Ce and CASN phosphor were fabricated. Maximum CRI Ra of 91 was achieved, which can be further enhanced by tuning the phosphor content. The three configurations of the phosphor glass composites were thermally aged at 50, 100, 150 and 200oC for duration of 480 hours. Degradation in PiG samples was 0.92%, GPG sample was 1.57% and GP samples was 1.97%. PiS showed a degradation of 15% at 150oC aging temperature with 14.4% degradation at 200oC after 120 hours of aging. Lasers form a better excitation source for high power applications. The PiG samples are tested with blue laser source to generate white light of 363 lumens. Surface PiGs also have an available surface which can be used to fabricate different types of flat optics. A surface PiG on the plane surface of a 5mm half ball lens is demonstrated. A 210 lumens source with FOV of 84o was obtained under laser excitation of 2W. The electronic version of this dissertation is accessible from https://hdl.handle.net/1969.1/198693 |
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