Circularly polarized vacuum ultraviolet coherent light generation using a square lattice photonic crystal nanomembrane
Kuniaki Konishi, Daisuke Akai, Yoshio Mita, Makoto Ishida, Junji Yumoto, Makoto Kuwata-Gonokami
Circularly polarized light in the vacuum ultraviolet (VUV) region is important for probing the structural and electronic 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 presented results suggest the possibility that the PCN can be used as a practical nonlinear medium for circularly polarized coherent VUV generation.