February 2016
Spotlight Summary by Sun-Kyu Lee
High luminous flux from single crystal phosphor-converted laser-based white lighting system
With the rapid development of GaN-based blue LDs in recent years, laser-based white lighting systems are expected to become the next-generation illumination systems, in order to make up for the weak points of LEDs, such as efficiency droop and low current density. Particularly in automotive headlamp systems, this technology enables long distance lighting, energy savings, and has a significant impact on the design of optical systems due to the small radiation area. However, for practical use the luminous efficacy still needs to reach the LED level.
In this Optics Express article, the authors demonstrate that laser-based white lighting systems are capable of emitting enough luminous flux for practical use in high power illumination systems using a GaN-based LD and single crystal YAG:Ce phosphor. The presented system has a peak luminous efficacy of 86.7 lm/W at an operating current of 1.4 A with a luminous flux of 515.4 lm, and a decreased luminous efficacy of 75.6 lm/W at a 3 A operating current with a peak luminous flux of 1100 lm. The luminous flux results are sufficient for meeting general illumination requirements. As for correlated color temperature (CCT) and color rendering index (CRI), this system produces a relatively high CCT of 7252K and a relatively low CRI of 60, due to its narrow wavelength peaks. However, this problem could be solved by adding different emission wavelength components, as mentioned in the article. In conclusion, the authors could achieve a suitable optical performance for use in a high power white light illumination system.
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In this Optics Express article, the authors demonstrate that laser-based white lighting systems are capable of emitting enough luminous flux for practical use in high power illumination systems using a GaN-based LD and single crystal YAG:Ce phosphor. The presented system has a peak luminous efficacy of 86.7 lm/W at an operating current of 1.4 A with a luminous flux of 515.4 lm, and a decreased luminous efficacy of 75.6 lm/W at a 3 A operating current with a peak luminous flux of 1100 lm. The luminous flux results are sufficient for meeting general illumination requirements. As for correlated color temperature (CCT) and color rendering index (CRI), this system produces a relatively high CCT of 7252K and a relatively low CRI of 60, due to its narrow wavelength peaks. However, this problem could be solved by adding different emission wavelength components, as mentioned in the article. In conclusion, the authors could achieve a suitable optical performance for use in a high power white light illumination system.
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Article Information
High luminous flux from single crystal phosphor-converted laser-based white lighting system
Michael Cantore, Nathan Pfaff, Robert M. Farrell, James S. Speck, Shuji Nakamura, and Steven P. DenBaars
Opt. Express 24(2) A215-A221 (2016) View: Abstract | HTML | PDF