Lens-free UV-LEDs?
Nitride Semiconductor adds photonic crystal structure to UV-LED
UV-LEDs that control the direction angle of light without using a lens have been long awaited.
Now, Nitride Semiconductor has added to a UV LED that emits at 385 nm, a photonic crystal structure with dimensions of 100 nm.
A photonic crystal is a structure in which the refractive index changes periodically. It can be used to confine light in a small area. By artificially creating a periodic structure with a size that matches the wavelength of light, it is possible to make metamaterials with novel optical properties.
Typically, LED chips require an optical lens made of resin or glass. But because resin and glass absorb UV, UV-LEDs have to use quartz lenses instead.
Nitride says that optical lens control of light emitted by micro-sized UV-LEDs (used with RGB phosphors to make colour displays) not only increases the cost, but makes it difficult to fabricate a fine lens array. By using photonic crystals instead, light can be controlled efficiently at low cost.
In addition to UV-LEDs, by applying photonic crystal processing to blue LEDs, Nitride says it is possible to make LED lights that cost less, are brighter, and consume less power.
