Researchers generate attosecond light from industrial laser

Date:
August 21, 2020
Source:
University of Central Florida
Summary:
Researchers are making the cutting-edge field of attosecond science
more accessible to researchers from all disciplines.



FULL STORY ========================================================================== University of Central Florida researchers are making the cutting-edge
field of attosecond science more accessible to researchers from all disciplines.


========================================================================== Their method to help open up the field is detailed in a new study
published today in the journal Science Advances.

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

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

"One of the main challenges of attosecond science is that it relies on
world- class laser facilities," says Michael Chini, an assistant professor
in UCF's Department of Physics and the study's principal investigator. "We
are fortunate to have one here at UCF, and there are probably another
dozen worldwide. But unfortunately, none of them are truly operated
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 in the direction of making attosecond pulses
more broadly accessible," Chini says.

"We show that industrial-grade lasers, which can be purchased commercially
from dozens of vendors with a price tag of around $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 or 3D laser mapping, but
at a much smaller scale. When an attosecond light pulse passes through
a material, the interaction with electrons in the material distorts the
pulse. Measuring these distortions allows researchers to construct images
of the electrons and make movies of their motion.

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



========================================================================== Producing the extremely short light pulses needed for attosecond
research - - essentially consisting of only a single oscillation cycle
of an electromagnetic wave -- has further required propagating the
laser through tubes filled with noble gases, such as xenon or argon,
to further compress the pulses in time.

But Chini's team has developed a way to get such few-cycle pulses out
of more commonly available industrial-grade lasers, which previously
could produce only much longer pulses.

They compress approximately 100-cycle pulses from the industrial-grade
lasers by using molecular gases, such as nitrous oxide, in the tubes
instead of noble gases and varying the length of the pulses they send
through the gas.

In their paper, they demonstrate compression to only 1.6 cycles, and
single- cycle pulses are within reach of the technique, the researchers
say.

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

"If 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," Beetar says.

"However, this alignment-caused enhancement is only present if the pulses
are long enough to both induce the rotational alignment and experience
the effect caused by it," he says. "The choice of gas is important since
the rotational alignment time is dependent on the inertia of the molecule,
and to maximize the enhancement we want this to coincide with the duration
of our laser pulses." "The reduction in complexity associated with using
a commercial, industrial- grade laser could make attosecond science
more approachable and could enable interdisciplinary applications by
scientists with little to no laser background," Beetar says.


========================================================================== Story Source: Materials provided by
University_of_Central_Florida. Original written by Robert H Wells. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. John E. Beetar, M. Nrisimhamurty, Tran-Chau Truong, Garima C. Nagar,
Yangyang Liu, Jonathan Nesper, Omar Suarez, Federico Rivas, Yi Wu,
Bonggu Shim and Michael Chini. Multioctave supercontinuum generation
and frequency conversion based on rotational nonlinearity. Science
Advances, 2020 DOI: 10.1126/sciadv.abb5375 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200821155739.htm

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