For the first time, a rainbow has been caught between a lens and a plate of glass. Exciting, innit?
Aside from it being exciting, it can also be used to store information. The device used is called a tapering waveguide, which guides light waves down its length. At a certain point in the structure, the medium transmitting the light becomes too narrow for the waves to pass through (i.e. the opening is smaller than its wavelength), effectively, trapping them.
Better than CDs?