Photonic quasicrystals boost LED emission characteristics

Aug. 24, 2006
Tailored photonic quasicrystal structures can help to efficiently extract light from LEDs and place it into a desired emission profile.
The case for high-brightness LED adoption lies increasingly with the potential cost savings made possible by reduced servicing, longer lifetimes and higher overall efficiency, as well as better technical functionality for many lighting applications. These cost benefits for the end-user are at present balanced by considerable performance challenges still facing the manufacturing industry, including providing sufficient luminous flux for projection applications.

To help achieve these goals, the use of photonic quasicrystal structures can both significantly enhance the luminous flux emitted by current LED technology and also place the light where it is needed.

High-brightness LEDs represent a multi-billion dollar market and strong future growth is anticipated in particular for ultra-high brightness devices. Before lighting applications can be addressed adequately, the industry still faces considerable performance-related challenges. The total and specific luminous flux currently available is still only borderline for some tasks, despite the increased efficacy achieved by modern LEDs. White light projection tasks such as automotive headlighting and projection displays are two examples of applications needing exceptionally highly efficient, as well as tailored, light output.

To help meet these demands, the effective light output of an LED can be optimized by both improving photon extraction efficiency and effectively shaping the intensity distribution for the task at hand, uniform or not. Planar photonic crystals, and in particular photonic quasicrystals, provide a cost-effective and flexible route to achieving this goal.


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