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Optical fibres provide an excellent platform for transmitting light over long distances, manipulating it and enhancing light-matter interaction. Now, the ‘Ultrafast & Twisted Photonics’ research group at the Max Planck Institute for the Science of Light (MPL) has developed a new hollow-core fibre which selectively guides optical vortices depending on their helicity and has potential applications in chiral sensing, vortex mode generation, and optical communications. The results were recently published in the journal ‘ACS Photonics’.
In addition to transmitting light over long distances, optical waveguides provide convenient ways of enhancing the interaction of light with matter and manipulating the properties of the guided light. Among several light attributes, pure polarization states are crucial for many applications and research areas. Over the years, several waveguides and structured materials have been developed to preserve linear and circular polarization over long distances and analyze these states with a sufficient degree of discrimination. In the past two decades, light with more complex polarization states, such as optical vortices, has also found multiple applications. The recent development of optical fibres guiding optical vortices has provided a route for using the orbital angular momentum carried by light for data multiplexing, thus increasing the capacity of fibre networks. Optical vortices have also been employed for chiral discrimination, which has applications in the pharmaceutical industry, and for controlling the motions of electrons. As a result, there is growing interest in developing new optical elements which can distinguish the helicity of optical vortices. However, the few structured materials developed for this purpose have not demonstrated high levels of discrimination.
In their work, the MPL scientists moved beyond the control and manipulation of light with linear and circular polarization and reported a new hollow-core waveguide which exhibits a strong helical dichroism. This means that the optical attenuation depends on the orbital angular momentum of the guided light. Thus, the waveguide transmits optical vortices with a specific helicity and largely attenuates vortices with the opposite helicity. The hollow waveguide can also be designed for spectral regions inaccessible using other optical systems, and filling it with liquid or gaseous media allows the study of light-matter interaction over extended lengths. Thus, these helically dichroic waveguides promise the realization of new devices with exceptional discrimination capabilities – comparable to and even exceeding those obtained for linear polarization using crystal-based polarizers, with multiple potential applications in chiral sensing, vortex mode generation and optical communications.
Caption:
Figure 1 (left): Schematic representation of twisted hollow-core fibre exhibiting helical dichroism. When launching vortex beams of topological charge 𝓁 =±1 into the waveguide, the transmission strongly depends on the sign of 𝓁. Figure 2 (right): Measured transmission for excitation of the fundamental mode (FM, 𝓁 = 0) and for vortex beams coupled into the twisted hollow-core fiber (square/star markers for s=±1).
Dr. Francesco Tani
Max Planck Institute for the Science of Light, Erlangen
Research Group Leader ›Ultrafast & Twisted Photonics‹
https://mpl.mpg.de / francesco.tani@mpl.mpg.de
Christof Helfrich, Michael H. Frosz, and Francesco Tani, “Giant Helical Dichroism in Twisted Hollow-Core Photonic Crystal Fibers”, ACS Photonics 2025 12 (2), 564-569.
DOI: https://pubs.acs.org/doi/10.1021/acsphotonics.4c02019
Caption see end of text.
Close collaboration of Dr. Francesco Tani (left) and Dr. Michael Frosz (right), leader of the Techno ...
MPL, Susanne Viezens
Criteria of this press release:
Journalists
Physics / astronomy
transregional, national
Scientific Publications
English
Caption see end of text.
Close collaboration of Dr. Francesco Tani (left) and Dr. Michael Frosz (right), leader of the Techno ...
MPL, Susanne Viezens
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