An ultra-high-intensity laser system, DIOCLES, was built at UNL to study the interactions of light with matter at the highest attainable field strengths. It has the highest combination of peak power and repetition rate of any laser in the U.S., 100 TW at 10 Hz. When focused, it is capable of directly increasing an electron's mass relativistically by 20 times.
The laser is named DIOCLES after the inventor, from 200 BC, of the parabolic reflector, which, to this day, remains the best focusing element by which the intensity of light can be increased.
Diocles begins with a modest amount of energy with a short pulse, then stretches the pulse and sends it through a series of amplifiers and titanium sapphire crystals to pump up its power. The secret to Diocles' high power is a compression stage, where the stretched, amplified pulse is compressed back into a very short, extremely powerful pulse. This trick prevents damage to the amplifiers. Then the powerful beam hits a parabolic reflector that focuses its power to extreme intensities.
"We can create a tiny 'sun' in the laboratory at the focus of the laser," physicist and Diocles director Donald Umstadter said. This extreme light is enabling Umstadter and his research team to pioneer a new research field, called high field science, which involves the nonlinear optics of ultra-high intensity lasers interacting with plasmas, or ionized gas. This is both basic and applied science that has applications to advanced radiation sources and particle accelerators.
What happens to matter at ultra-high light intensities?
The focused Diocles laser light is the strongest produced on Earth, creating conditions only found in stars like the Sun. Matter subjected to such conditions becomes heated to extreme temperatures and pressures, and converts to the fourth state of matter: plasma, or what is commonly called fire. We can use Diocles to study -- under controlled conditions -- the interactions of light with the hottest fire ever produced in a laboratory.