Study: Laser dye regenerates in darkness

PULLMAN, Wash., April 10 (UPI) -- U.S. physicists have found a laser dye that loses its ability to fluoresce when struck by a laser beam can regain that ability after "resting" in the dark.

Washington State University physicist Mark Kuzyk and colleagues determined recovery begins within 30 minutes and is nearly complete after eight hours of rest.

"It's almost as if you have a piece of paper that's yellowed over time and you put it in a dark room for a day and it comes back brand-new," said Kuzyk.

The research team, including students Ye Zhu and Juefei Zhou, discovered the "self-healing" property in AF455, a dye compound designed to excel at two-photon absorption. That's a process in which the absorption of light energy from a laser causes a change in the molecule that can be harnessed for various purposes. Many molecules also glow, or fluoresce, during two-photon absorption, which allows researchers to monitor the process.

The research appears in the April 15 issue of the journal Optics Letters and is available online at opticsinfobase.org/abstract.cfm?msid=78687.