Nichia Discloses Plans for Blue-Violet, Blue Laser Products, White Light Source Using Blue Laser

May 7, 2007 18:26 Tadashi Nezu, Nikkei Electronics

Nichia Corp. has announced product plans of blue-violet semiconductor laser for next-generation DVD drive, high-power blue semiconductor laser for light sources of image display equipment and a white light source using blue semiconductor laser at the laser technology special seminar co-located at Laser Expo 2007 held at Pacifico Yokohama from April 25 to 27, 2007.

To start volume production and shipments of 250 mW product in January 2008

Nichia will start mass-producing and shipping a model of the blue-violet semiconductor laser, which can emit 180 mW light pulse for recorder/players, in June 2007 and a 250 mW model in January 2008. Despite the use of an optical head, next-generation DVD equipment can generally record at 4x to 6x speed on a dual-layer disc using blue-violet semiconductor laser models able to emit around 200 mW light pulse and 8x speed using around 240 mW models. Nichia is currently mass-producing a 130 mW model toward recorder/players. The company plans to mass-produce a 320 mW model for 10x speed recording onto dual-layer discs in the first half of 2008.

Nichia has also been mass-producing a model capable of continuous 20 mW output focusing on low-cost manufacturing for replay only equipment since April 2007.

Targeting over 1 W light output

Regarding high-power blue semiconductor laser for use as a light source of image display devices including rear projectors, the company delivered properties of a model, which continuously outputs 500 mW light at an emission wavelength of 445 nm, as well as its policies for future development.

When continuously emitting 500 mW light, drive current and voltage are 480 mA and 4.8 V, respectively, and a life extends to about 30,000 hours. The life is defined as a time before the light output halves with a drive current maintained unchanged. In general, a life of 10,000 hours is required for display light sources, said Nichia.

Nichia achieved the wavelength of 445 nm, longer than the 405 nm products used for next-generation DVD, by overcoming challenges such as less light packed in a laser device and more distortion generated in crystals as wavelength grows longer. Such challenges reportedly boosts threshold current density as a light emission wavelength becomes longer and makes it difficult for devices to emit high-efficiency laser. Although refraining from specifying detailed information, Nichia realized 1.8 kA/cm2 threshold current density by optimizing growth conditions for laser devices and improving the laser structure. The company explained it prevented degradation caused by laser end by expanding the beam diameter, among other efforts, to achieve the higher light output.

Nichia projects to realize light output of over 1 W, as well as a longer light emission wavelength of 460 nm from now. The company intends to boost light output by developing a dedicated package with higher heat liberation. Nichia currently uses a multi-purpose can package, which is employed for blue-violet semiconductor laser for next-generation DVD, in a bid to lower costs. Despite the low manufacturing costs maintained by sharing manufacturing facilities and materials with blue-violet semiconductor laser, this package's heat resistance is relatively high, according to the company.

Nichia also introduced a white light source using its blue semiconductor laser at the session. This light source transmits light emitted from blue semiconductor laser through optical fiber and obtains pseudo white light by converting the blue light wavelength using phosphor coated on the optical fiber's end area, where light is transmitted. Key target applications are light sources of displays and headlamps. The company plans to start sample shipments of a model that achieves 85 cd/mm² luminance with 96 lm beam at 500 mA current in the third quarter of 2007.

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