As write speeds in optical drives are pushed higher, laser diodes - the components that produce the light beam which is used to read and write data to and from the disk - need to be more powerful. Both Sharp and Mitsubishi Electric have developed higher-power laser diodes, paving the way for 4x DVD-R, -RW, -RAM and +RW drives.
The new components can deliver power levels of 100 milliwatts in pulses, making them around 40% more powerful than the 70-milliwatt types used for 2x drives. This means it will be possible to write data to a disk at a rate of 44Mbps, speeding up the time taken to write an entire 4.7Gbyte disk to around 14 minutes. Double-speed drives take twice as long and single-speed drives take almost an hour to carry out the same task.
Power was not the only barrier to be overcome before the companies could begin selling the devices commercially, according to Tetsuya Yagi, manager of Mitsubishi Electric's high-power optical device group. Higher-power laser diodes often have very short lives and both companies had to work on extending their life so that they would not burn out after a few hours, days or weeks of use, he said. The laser diode produced by Yagi's group has a life of around 4,000 hours, he said.
Both companies are about to begin shipping samples of the higher-power laser diodes and expect to begin commercial production in May or June. With each company preparing to produce 100,000 diodes per month, demand is expected to take off fast for the components as corporate and consumer users choose the faster drives.
Sales of drives are expected to jump from an estimated 1.3 million in 2001 to 9.8 million this year, according to Jon Peddie, president of Jon Peddie Research, speaking at a press conference organised by the Recordable DVD Council, an industry promotion group, at the Consumer Electronics Show in Las Vegas in January. He predicted drive shipments would surpass 50 million in 2005.
The next step in rewritable DVD drives, the jump to 6X models, is not expected until sometime in 2003 when laser diodes capable of delivering 120 milliwatts of power will become available, said Yagi.