news digest ♦ LEDs
waves, the metamaterial exhibits a negative index of refraction to incoming light regardless of its angle of travel.
The researchers say this realisation of a Veselago flat lens operating in the UV is the first such demonstration of a flat lens at any frequency beyond the microwave. By using other combinations of materials, it may be possible to make similarly layered metamaterials for use in other parts of the spectrum, including the visible and the infrared.
The metamaterial flat lens achieves its refractive action over a distance of about two wavelengths of UV light, about half a millionth of a metre - a focal length challenging to achieve with conventional refractive optics such as glass lenses.
What’s more, transmission through the metamaterial can be turned on and off using higher frequency light as a switch, allowing the flat lens to also act as a shutter with no moving parts.
“Our lens will offer other researchers greater flexibility for manipulating UV light at small length scales,” says Lezec. “With its high photon energies, UV light has a myriad of applications, including photochemistry, fluorescence microscopy and semiconductor manufacturing. That, and the fact that our lens is so easy to make, should encourage other researchers to explore its possibilities.”
The new work was performed in collaboration with researchers from the Maryland NanoCentre at the University of Maryland, College Park; Syracuse University; and the University of British Columbia, Kelowna, Canada.
Panasonic UV lasers and phosphors energise white lights
The company’s newly developed technology will enable wider variation in design and a higher brightness and smaller form factor in data projectors and vehicle headlights
Panasonic Corporation has developed a semiconductor white light source capable of outputting luminous flux in the 10,000-lumen class.
An increased light output was achieved due to the high- efficiency, low-loss design and modularisation of the near-ultraviolet semiconductor laser used in the light
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www.compoundsemiconductor.net June 2013 source.
A high luminous flux of white light was realised through the development of a phosphor material that is not subject to luminance saturation even when irradiated with high-intensity laser light.
Luminance saturation is when the optical power may decline as the intensity of incident radiation increases.
The use of a laser with a smaller light-emitting area and superior light emission directionality to LEDs has made a compact optical configuration that boasts higher brightness and a smaller form factor possible. Panasonic says this technology opens the way to the greater use of semiconductor light sources in the projection and lighting market.
The new technology has the following features:
- By increasing the output of the near-ultraviolet laser in the light source to ten times that of a conventional Panasonic laser, the industry’s highest light output of 60 watts (W) has been achieved. This is based on a survey by Panasonic on near-ultraviolet laser up to May 24th, 2013. The miniaturised laser module, a component where two or more semiconductor lasers are mounted functioning as a light source, can be incorporated into a wider range of equipment.
- The use of a newly developed phosphor material has increased blue light emissions by 40 percent when irradiated with 60W near-ultraviolet semiconductor laser light. This contributes to the realisation of a 10,000-lumen class high-luminous flux white light source through the red, green and blue phosphors.
- The generation of red, green and blue lights from only one type of laser light using a rotating phosphor wheel simplifies the optical system and ensures that the laser is projected directly onto the screen. The phosphor wheel is a component where light is shined onto the surface of a disc, onto which phosphor has been applied, which is then rotated by a motor on the central shaft, continuously creating phosphor light.
This development is based on the following new technologies:
- High-output, low-loss laser design technique with wider near-ultraviolet laser optical waveguide and optimised light loss control.
- Phosphor material technology that utilises the high- density crystalline structure of SMS (Sr3MgSi2O8) phosphor to control the density of the luminescent centre and thus prevent luminous saturation.
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