Japanese electronics firm Sanyo has announced a new type of blue laser diode, which it said could double the capacity of existing Blu-ray discs to 100GB.

Although still under development, Sanyo claimed that the new laser could support drives that can write to Blu-ray discs at 12x speed over four layers of 25GB each.

Current Blu-ray recorders can write at speeds of around 6x, with some 8x burners due out soon.

However, with a write speed of 12x this means the drive would have an effective writing speed of 432Mbps, allowing a 100GB disc to be filled in under 10 minutes.

The biggest current drawback is that, in order to be able to write to four layers instead of two as is the case today, the new beam emits 450mW, nearly double the 250mW from existing lasers.

Further development and the need for approval from the Blu-ray Disc Association means that drives sporting the breakthrough diode could be a few years away yet, but Sanyo hopes products will be available before 2011.

Some observers have commented that the plunging costs of digital storage has effectively rendered optical drives useless.

However, many organisations still see it as an effective method of data backup and an easy way of transferring large amounts of data via post or courier, meaning that many could find the doubling of capacity and the huge increase in write speed to be a major advantage.