High luminous flux from single crystal phosphor-converted laser-based white lighting system
Farrell, Robert M.
Speck, James S.
DenBaars, Steven P.
KAUST Grant NumberSB140014
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AbstractThe efficiency droop of light emitting diodes (LEDs) with increasing current density limits the amount of light emitted per wafer area. Since low current densities are required for high efficiency operation, many LED die are needed for high power white light illumination systems. In contrast, the carrier density of laser diodes (LDs) clamps at threshold, so the efficiency of LDs does not droop above threshold and high efficiencies can be achieved at very high current densities. The use of a high power blue GaN-based LD coupled with a single crystal Ce-doped yttrium aluminum garnet (YAG:Ce) sample was investigated for white light illumination applications. Under CW operation, a single phosphor-converted LD (pc-LD) die produced a peak luminous efficacy of 86.7 lm/W at 1.4 A and 4.24 V and a peak luminous flux of 1100 lm at 3.0 A and 4.85 V with a luminous efficacy of 75.6 lm/W. Simulations of a pc-LD confirm that the single crystal YAG:Ce sample did not experience thermal quenching at peak LD operating efficiency. These results show that a single pc-LD die is capable of emitting enough luminous flux for use in a high power white light illumination system.
CitationCantore M, Pfaff N, Farrell RM, Speck JS, Nakamura S, et al. (2015) High luminous flux from single crystal phosphor-converted laser-based white lighting system. Optics Express 24: A215. Available: http://dx.doi.org/10.1364/oe.24.00a215.
SponsorsThis work was supported by the KACST(SB140013)-KAUST(SB140014)-UCSB Solid State Lighting Program (SSLP) and the Solid State Lighting & Energy Electronics Center. A portion of this work was done in the UCSB nanofabrication facility, part of the NSF NNIN network (ECS-0335765), as well as the UCSB Materials Research Lab, which is supported by the NSF MRSEC program (DMR-1121053).
PublisherThe Optical Society