Circularly polarized vacuum ultraviolet coherent light generation using a square lattice photonic crystal nanomembrane

Circularly polarized light in the vacuum ultraviolet (VUV) region is important for probing the structural and elec-tronic properties of matter. Moreover, a circularly polarized VUV coherent light enables one to observe the dynamics of biomolecules and electron spins in solids. The development of a table-top technology to directly generate circularly polarized VUV coherent light is of great value, owing to the limitation of polarization control elements for the VUV region. However, solid-state nonlinear media for this purpose, which simplifies the setup, have not been presented. Here, we demonstrate a solid-based method for the direct generation of circularly polarized VUV coherent light using third -harmonic generation in a dielectric square lattice photonic crystal nanomembrane (PCN). We found that the waveguide resonance of PCN with fourfold rotational symmetry, irradiated by a circularly polarized fundamental beam, generates circularly polarized third harmonic at 157 nm with sufficient intensity for VUV spectroscopic applications. The pre-sented results suggest the possibility that the PCN can be used as a practical nonlinear medium for circularly polarized coherent VUV generation. (c) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement