Researchers have developed a new technique that generates novel light beams from synchrotron light sources. This latest breakthrough paves the way to create X-ray beams.
Structured light is generated through the process of producing and applying light to a surface. This light is critical in various present-day devices, for example, microscopic technology, dual photography, and 3D scanners.
A group of Japanese researchers, headed by Shunya Matsuba, an assistant professor at the Hiroshima Synchrotron Radiation Center at Hiroshima University, has demonstrated that structured light, in the form of a vector beam (that is, light beams whose direction of polarization rotates around its axis) can be generated from the superposition of a pair of optical vortex beams—light beams that include a point of zero intensity, creating a spiral phase structure.
"We have demonstrated the generation of the vector beam using synchrotron radiation. This work has opened a way to generate X-ray vector beams," states co-author Prof. Masahiro Katoh of the Institute for Molecular Science (IMS) at the National Institutes of Natural Sciences/Sokendai in Japan.
However, it has been difficult to produce structured light in the X-ray wavelengths, and the latest method demonstrated by the Japanese team can possibly enable the application of such structured light in research areas that can be accessed only with synchrotron radiation, for instance, X-ray crystallography and X-ray absorption spectroscopy.
The researchers’ approach was based on a method that generates circularly polarized light from a pair of linearly polarized ones, whose directions of polarization are orthogonal to one another. In synchrotron light sources, this technique has been applied to evenly polarized beams emerging from a pair of undulators. An undulator is basically a device that produces quasi-monochromatic light with different polarizations.
Matsuba and his group used this method for two vortex beams emitted from a couple of helical undulators positioned together. The study follows earlier researches in which optical components and lasers were used for producing vector beams, with wavelengths typically within the near-infrared or visible parts of the electromagnetic spectrum.
The results of the study have been reported in the journal of Applied Physics Letters in July 2018.
Katoh further went on to elucidate that "the next step of this research is to demonstrate the generation of vector beams of other types, for example, radially polarized beams. Our ultimate goal is to control all the optical properties of synchrotron radiation, such as wavelength, coherence, spatial, temporal structures and so on." This will present new opportunities in a wide range of fields, such as scattering, X-ray diffraction, and emission/absorption spectroscopy, thanks to the novel method of producing structured light which has been revealed in this study.
The Japanese Society for the Promotion of Science (JSPS), the Joint Research by the National Institutes of Natural Sciences (NINS), and IMS supported the work.