Purdue laser shines light on new discovery

WEST LAFAYETTE, Ind. (WLFI) - It's a groundbreaking project at Purdue with lasers that's four to five years in the making.  

The equipment cost a cool $500,000.  Just the setting up of the elaborate mirrors took a year's worth of time.

But the pay-off is something that's never been seen before.  By flashing a high-powered laser at a piece of copper electrons from the air, assisted by electrons from the target material, form a specific state of matter called plasma.

The images look like a flume from a piece of copper, back toward the beam of laser.  The flume is the electrons that have turned into plasma.  The pictures are taken picoseconds after a flash of laser that lasted 0.1 picoseconds.

How quick is a picosecond?  There are a trillion picoseconds in a single second.

"We could see it through modeling, but until we could see it physically, there's no proof," said Purdue Mechanical Engineering Professor Yung Shin.  "So we were very, very excited to actually start seeing these images."

To an untrained eye, it may not seem like much.

But Shin said it's an important discovery.  

It demonstrates that a laser loses energy because it has to travel through the plasma.  It also means the plasma can be used to analyze the material the laser is being beamed onto.

"Finding new things in nature is like finding a present under the Christmas tree," said Shine.  "It's very, very exciting."

Shin said this discovery has future applications.  A laser could create controlled plasma to hollow out a precise shape inside a material.  The plasma shows some possibilities of helping researchers develop a primary energy source mirroring research in areas of science like fusion.

"It's a long-term goal, but it's very challenging," said Shin.  "But I think it will help in that direction."

To put it in perspective, a picosecond makes a nanosecond look slow.  There's a trillion picoseconds in a single second.  One trillion seconds is roughly equivalent to 32,000 years.

Shin said shooting pictures of a laser's interaction with a material at the picosecond level is a first.  The distance of the plume is just a few microns large.

He hopes to continue research by studying the effect of a laser pulse on other materials including semiconductors and insulators.  He also wants to amplify the plasma field by adding a second laser beam.

Shin added the breakthrough would not have been possible without the efforts of doctoral student Wenqian Hu.