Despite most research now being put into multi-layer and holographic discs to achieve higher density discs, research into squeezing more data onto a single layer still continues, as a group of scientists researching zinc oxide films has developed a high efficient ultraviolet laser. These scientists claim that their creation will allow for more efficient read back of data from high density optical discs than with traditional gallium nitrate based semiconductor lasers. The laser's luminescence property has also been found to last longer under the shorter UV wavelengths.
At this time, it is unclear what type of optical media these semiconductors will be targeted at, especially since the widely used material in optical discs, polycarbonate, is unstable when irradiated by UV light. Another drawback is that the potential increase in storage density over blue-laser technologies would be only in the region of 1.2 to 1.5 times higher storage capacity. As a result, with the huge investment in polycarbonate-based optical media, it is more likely to see zinc oxide based blue lasers take over the current generation than to see a new optical disc format using UV laser technology.
Further info can be read in this Ars Technica article.
