02 Oct 2003
Toshiba says that its 200 mW blue diode laser is good enough for the next generation of optical data storage systems.
Japanese electronics giant Toshiba claims to have developed a blue-violet diode laser with record low noise and high output power.
The device, which is based on gallium nitride, emits 200 mW at 409 nm in continuous-wave mode. Toshiba says that the noise level of –132 dB/Hz is the best ever achieved in a blue diode laser, although the figure quoted was measured when the laser emitted only 3 mW.
“The laser performance meets the requirements for blue-violet laser-based optical disc systems that will emerge in the near future,” said the company.
Over the next few years, blue-diode-laser-based optical disc systems are set to replace the systems based on red diode lasers that are used in current DVD technology. Because the next-generation discs feature dual-layer-disc and high-speed recording, there is a need for a more powerful laser source than that used for conventional recording. Low noise and a stable beam profile are also crucial.
Toshiba says that three technological refinements contributed to the development. A high quantum efficiency was achieved by optimizing the density of impurities used to dope the laser, leading to a low operating current (164 mA) at high output levels.
The high output itself resulted from the coatings Toshiba used in the light-emitting facets of the laser structure. These coatings also led to the low noise level.
The third factor was Toshiba’s semiconductor processing, which produced a device structure capable of supplying a stable electric current in the active area.
Toshiba will be showing off the new laser at the CEATEC JAPAN 2003 exhibition, which runs on 7-10 October at the Makuhari Messe.
Michael Hatcher is technology editor of Opto & Laser Europe magazine.
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