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Something from Nothing

Thursday, 03 November 2022

In a recent joint publication in Optica between members of the Optics of Nano and Quantum Materials group (OpNaQ) from the University of Graz and the Max Planck – uOttawa Centre for Extreme and Quantum Photonics, an experimental method of producing structured light beams was reported on. By simply using a homogenous interface with a vanishing permittivity, the researchers managed to convert standard optical beams into light beams exhibiting a sculpted phase front.

The pursuit of generating uniquely structured forms of light is paramount to various applications ranging from optical communications to particle manipulation. One degree of freedom in light which is of particular interest for such applications is the phase in the form of orbital angular momentum (OAM). For instance, one can encode information in beams with various OAM states, or focus beams carrying OAM onto particles inducing mechanical torque. The ability to craft these beams with minimal losses while still avoiding complex bulky technology remains of chief importance today. Usually, standard methods involve structured materials or devices to manipulate input beams in a position-dependent manner, eventually leading to the desired structure of the light field.

Members of the OpNaQ group at the University of Graz, in collaboration with the Max Planck – uOttawa Centre for Extreme and Quantum Photonics, have now taken advantage of a simple homogenous thin film whose electric permittivity sits at zero. While such a regime offers many unique consequences, one in particular is the coupling between spin, i.e., circular or elliptical polarization, and orbital-angular momentum. By exploiting this fundamental property, they were able to produce optical beams featuring OAM created by enhanced spin-orbit coupling.

Such an achievement allows one to explore the possibilities of beam shaping without the requirement of complex fabrication design and rigorous alignment. Furthermore, by only requiring a thin film of such a material, a playground of designs can be explored for beam shaping with permittivity-near-zero metasurfaces and nano-photonic devices.

The article was recently published in Optica. More details can be found in the article (see link below).


Jörg S. Eismann, Lisa Ackermann, Brian Kantor, Sergey Nechayev, M. Zahirul Alam, Robert Fickler, Robert W. Boyd, and Peter Banzer, "Enhanced spin–orbit coupling in an epsilon-near-zero material," Optica 9, 1094-1099 (2022); https://doi.org/10.1364/OPTICA.469079

Contact: Peter Banzer, peter.banzer(at)uni-graz.at


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