Violet laser breakthrough builds Blu-Ray momentum

SUMITOMI SAID it has started to mass produce two inch low dislocation gallium nitride (GaN) substrates, an essential component to violet lasers for use in Blu-Ray and Advanced Optical Disc machines.

The company said it is now producing 200 of these substrates a month but will step up production of the parts to 500 by October.

While ordinary DVD players normally use red lasers, which rely on gallium arsenide (GaAs) as the light source for reading and writing date, Sumitomi said that next generation optical disc components are needed to record and playback digital terrestrial HDTV content.

Future products, including the Sony Blu-Ray player, have over five time the capacity of red laser based players, the company said.

A violet laser uses a laser emission from the gallium nitride epitaxial layer, but sapphire substrates deliver a lower lifetime and power output, Sumitomi said.

Sumitomi Electric said it has managed to develop GaN substrates of two inch diameter, and with low dislocation density of around 100,000 or less per square centimetre. µ