Researchers generate attosecond light from industrial laser

Researchers from the University of Central Florida make the leading field of attosecond science more accessible to researchers from all disciplines.

Their method of opening up the field is detailed in a new study published in the journal today Science Advances.

An attosecond is one billionth of a billionth of a second, and with the ability to make measurements with attosecond precision, researchers can study the rapid motion of electrons in atoms and molecules at their natural time scale.

Measuring this rapid motion can help researchers understand fundamental aspects of how light interacts with matter, which can inform efforts to harvest solar energy for energy generation, detect chemical and biological weapons, perform medical diagnostics and more .

“One of the major challenges of attosecond science is that it requires world-class laser equipment,” said Michael Chini, an assistant professor in UCF’s Department of Physics and the study’s lead researcher. “We are fortunate to have one here at UCF, and there are probably another dozen worldwide. But unfortunately neither of them are really served as ‘user facilities’, where scientists from other fields can come in and use them for research. “

This lack of access creates a barrier for chemists, biologists, materials scientists and others who could benefit from applying attosecond science techniques to their fields, Chini says.

“Our work is a big step toward making attosecond pulses more widely accessible,” says Chini.

“We show that industrial-class lasers, which can be purchased commercially from dozens of vendors with a price tag of about $ 100,000, can now be used to generate attosecond pulses.”

Chini says the setup is simple and can work with a wide variety of lasers with different parameters.

Attosecond science works somewhat like sonar as 3-D laser mapping, but on a much smaller scale. When an attosecond light pulse passes through a material, the interaction with electrons in the material disrupts the pulse. By measuring these disturbances, researchers can construct images of the electrons and make films of their motion.

Typically, scientists have used complex laser systems, which require large laboratory facilities and clean room environments, as the driving lasers for attosecond science.

Producing the extremely short light pulses required for attosecond research – essentially consisting of only a single oscillation cycle of an electromagnetic wave – the laser still needs to propagate through tubes filled with noble gases, such as xenon or argon, around the pulses. to further compress the time.

But the Chini team has developed a way to get such pair-cycle pulses from more widely available industrial-class lasers, which previously could produce much longer pulses.

They compress about 100-cycle pulses of industrial lasers with molecular gases, such as nitric oxide, in the tubes instead of noble gases and vary the length of the pulses they send through the gas.

In their paper, they demonstrate compression to only 1.6 cycles, and pulses with one cycle are within range of the technique, the researchers say.

The choice of gas and the duration of the pulses are important, says John Beetar, a doctoral student in the Department of Physics at UCF and the lead author of the study.

“When the tube is filled with a molecular gas, and in particular a gas of linear molecules, there can be an enhanced effect due to the tendency of the molecules to align with the laser field,” says Beetar.

“However, this improvement-induced improvement is only present if the pulses are long enough to both induce the rotational position and experience the effect thereby,” he says. “The choice of gas is important because the rotational position time depends on the inertia of the molecule, and to maximize the improvement we want this to coincide with the duration of our laser pulses.”

“The reduction in complexity associated with using an industrial-grade commercial laser could make attosecond science more accessible and enable interdisciplinary applications by scientists with little to no laser background,” says Beetar.