Whatever happened to ultraviolet lasers?

[radagast]

Back, several years ago, when I first heard of research into producing inexpensive blue lasers which I then read would be used for HD replacements for DVD, I also read that some progress had been made in regards to ultra-violet lasers, which have even a smaller beam width then blue. Of course that would have meant even more data on a disc than a blue laser system. What happened to it?

I also remember a company coming out with a particle beam system that had a 50nm width beam which would have allowed 200gb on a DVD size disc. Apparently that project was abandoned as well.