Dielectric cross-shaped-resonator-based metasurface for vortex beam generation at mid-IR and THz wavelengths
Dharmavarapu Raghu,
Izumi Ken-ichi,
Katayama Ikufumi,
Ng Soon Hock,
Vongsvivut Jitraporn,
Tobin Mark J.,
Kuchmizhak Aleksandr,
Nishijima Yoshiaki,
Bhattacharya Shanti,
Juodkazis Saulius
Affiliations
Dharmavarapu Raghu
Centre for NEMS and Nanophotonics (CNNP), Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
Izumi Ken-ichi
Physics Department, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
Katayama Ikufumi
Physics Department, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
Ng Soon Hock
Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
Vongsvivut Jitraporn
Infrared Microspectroscopy Beamline, Australian Synchrotron, Clayton, Victoria 3168, Australia
Tobin Mark J.
Infrared Microspectroscopy Beamline, Australian Synchrotron, Clayton, Victoria 3168, Australia
Kuchmizhak Aleksandr
Institute of Automation and Control Processes, Far Eastern Branch, Russian Academy of Sciences, Vladivostok 690041, Russia
Nishijima Yoshiaki
Department of Electrical and Computer Engineering, Graduate School of Engineering, Yokohama National University, 79-5 Tokiwadai, Hodogaya-ku, Yokohama 240-8501, Japan
Bhattacharya Shanti
Centre for NEMS and Nanophotonics (CNNP), Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai 600036, India
Juodkazis Saulius
Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology, Hawthorn, Victoria 3122, Australia
Metasurfaces are engineered thin surfaces comprising two-dimensional (2D) arrays of sub-wavelength-spaced and sub-wavelength-sized resonators. Metasurfaces can locally manipulate the amplitude, phase, and polarization of light with high spatial resolution. In this paper, we report numerical and experimental results of a vortex-beam-generating metasurface fabricated specifically for infrared (IR) and terahertz (THz) wavelengths. The designed metasurface consists of a 2D array of dielectric cross-shaped resonators with spatially varying length, thereby providing the desired spatially varying phase shift to the incident light. The metasurface was found to be insensitive to the polarization of the incident light. The dimensions of the cross-resonators were calculated using rigorous finite-difference time-domain analysis. The spectral scalability via physical scaling of the meta-resonators is demonstrated using two vortex-generating optical elements operating at 8.8 μm (IR) and 0.78 THz. The vortex beam generated in the mid-IR spectral range was imaged using a Fourier transform IR (FTIR) imaging miscroscope equipped with a focal plane array detector. This design could be used for efficient wavefront shaping and various optical imaging applications in the mid-IR spectral range, where polarization insensitivity is desired.
