Researchers develop atomic laser operating at the shortest wavelength yet

(Phys.org)—A team of researchers with affiliations to several facilities in Japan has succeeded in developing an atomic laser that operates at the shortest wavelength yet. In their paper published in the journal Nature, the group describes how they built their laser and how it performed. Linda Young, with Argonne National Laboratory in the U.S. offers a News & Views piece on the work done by the team in the same journal edition, highlighting the development effort and the means by which the result was tested.

As Young notes, X-rays are able to provide us pictures of the inside of things such as body parts, because they are able to penetrate matter and then to offer a contrast, via magnetic, chemical or elemental properties between different body parts inside. She also notes that back in 1960, Theodore Maiman demonstrated for the first time that a laser, if operated at an optical wavelength could also operate as a an X-ray, but at a much smaller scale—this opened the door to atomic X-ray machines that could offer us images of such things as molecules. But, as the researchers with this new effort note, there is still a desire to produce lasers with ever shorter wavelengths that generate coherent X-rays—because as the wavelength is shortened, the better the resolution of the device.

Another bonus is that it allows for shorter pulses of light, which allows for better resolution when engaged in probe measurements. Moving to a shorter wavelength, Young notes, has been held back due to a problem inherent with the technology, namely that the power required to operate them skyrockets as the wavelength grows shorter, requiring, for example, a 1015-fold increase in pump power density when going from a laser operating at 7,000Å to one running at 1.54Å. To overcome this limitation, the researchers used free-electron type lasers that are based on self-amplified spontaneous emissions. When using a copper target, they found that they could produce a hard-X-ray shell atomic laser capable of operating at a wavelength of 1.5 ångströms.

While impressive, the technology is not yet ready for primetime, Young, notes, the laser did not achieve saturation and some tests, such as angular divergence were not performed. Still, she notes, the work done by the team and others suggests that researchers will very soon be able to make use of very-short wavelength based lasers, offering perhaps, unprecedented resolution and atomic measurement capabilities.

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