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Sharp enters the non-polar GaN fray

The leading diode laser and consumer electronics manufacturer is hoping to push GaN lasers to longer wavelengths for color display applications. The field of non-polar GaN lasers, currently dominated by Rohm Corporation and the University of California, Santa Barbara, now has another big player in the shape of Sharp Corporation. This firm's researchers, like the other groups, have turned to this material to avoid built-in polarization fields found in conventional c -plane GaN. These fields reduce laser output efficiency and shorten emission wavelengths, in a blue-shift effect that worsens at higher injection currents. Sharp's 400nm blue laser Non-polar m -plane GaN doesn't have these fields, so substrates made of this material are promising candidates for fabricating blue lasers with longer wavelengths, nearer the green part of the spectrum (see related stories). Therefore, rather than the 400 nm laser diodes it makes using c -plane GaN for its Blu-ray pla...
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Toshiba claims GaN microwave power record

Toshiba claims GaN microwave power record The Japanese conglomerate turns up the power for high-definition satellite broadcasting with its Ku-band GaN-on-SiC HEMT. Toshiba has produced a GaN HEMT with an output power of 65.4 W at 14.5 GHz, that it hopes will replace competing electron-tube technologies in satellite applications. According to the Japanese company, this is the highest power-output FET to operate in the Ku-band, the region of the microwave spectrum between 12 and 18 GHz. Toshiba pushes Ku-Band amps Presented at European Microwave Week on October 8, the device will be sampled at the end of 2007 and should enter mass production in March 2008. The GaN HEMTs are marketed for high-capacity, high-definition satellite broadcasting base stations and high-power radar systems, which both require high-power amplifiers. “Demand is particularly strong for GaN devices, which offer advantages over GaAs devices in heat dissipation and high power performance characteristi...
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White LEDs offer radio-free wireless option

White LEDs offer radio-free wireless option A photonic alternative to WLAN has been shown to exceed 100 Mbit/s and could provide bandwidth in a currently unlicensed area of the spectrum, if it can conform to general illumination standards. Thanks to white LEDs, overhead lighting could soon be used to transmit data over a RF-free wireless connection. That's according to Joachim Walewski from Siemens Corporate Technology, who has modulated the light emission from white LEDs in order to make a 101 Mbit/s wireless link with a PiN diode photodetector. “With this, you can have interference-free communication,” Walewski pointed out, adding that the visible spectrum is currently free of any requirements for communication licenses. Siemens is currently exploring the technology in order to keep pace with a competing Japanese collaboration that expects to bring similar technology to market by 2011, Walewski says. His Munich-based team claims to be the first to have boosted ...
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