Abstract
Ultra-compact, low-loss, fast, and reconfigurable optical components, enabling manipulation of light by light, could open numerous opportunities for controlling light on the nanoscale. Nanostructured all-dielectric metasurfaces have been shown to enable extensive control of amplitude and phase of light in the linear optical regime. Among other functionalities, they offer unique opportunities for shaping the wave front of light to introduce the orbital angular momentum (OAM) to a beam. Such structured light beams bring a new degree of freedom for applications ranging from spectroscopy and micromanipulation to classical and quantum optical communications. To date, reconfigurability or tuning of the optical properties of all-dielectric metasurfaces have been achieved mechanically, thermally, electrically or optically, using phase-change or nonlinear optical materials. However, a majority of demonstrated tuning approaches are either slow or require high optical powers. Arsenic trisulfide (As2S3) chalcogenide glass offering ultra-fast and large χ(3)nonlinearity as well as a low two-photon absorption coefficient in the near and mid-wave infrared spectral range, could provide a new platform for the realization of fast and relatively low intensity reconfigurable metasurfaces. Here, we design and experimentally demonstrate an As2S3 chalcogenide glass based metasurface that enables reshaping of a conventional Hermite-Gaussian beam with no OAM into an OAM beam at low intensity levels, while preserves the original beam's amplitude and phase characteristics at high intensity levels. The proposed metasurface could find applications for a new generation of optical communication systems and optical signal processing.
Highlights
The discovery of the fact that photons can carry an orbital angular momentum (OAM) opened a new area of optical physics and led to new understanding of a wide range of phenomena [1,2,3,4]
First steps toward the realization of microscale, planar optical components based on liquid crystal technology [14] and optical metasurfaces [16,17,18,19,20,21,22,23,24,25,26,27,28] have been made
While many of the first demonstrations of these devices were designed for generating OAM beams with a specific and fixed topological charge, reconfigurability is one of the desired characteristics allowing switching from one charge to another or from the OAM beam to a beam not carrying an OAM
Summary
The discovery of the fact that photons can carry an orbital angular momentum (OAM) opened a new area of optical physics and led to new understanding of a wide range of phenomena [1,2,3,4]. The output beam reconfigurability is enabled by the design of the metasurface described in detail below, that uses highly nonlinear ChG glass.
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