Dielectric cross-shaped-resonator-based metasurface for vortex beam generation at mid-IR and THz wavelengths

Nanophotonics

article

Raghu Dharmavarapu¹  Shanti Bhattacharya¹  Saulius Juodkazis²  Ken-ichi Izumi⁶  Ikufumi Katayama⁶  Soon Hock Ng²  Jitraporn Vongsvivut⁷  Mark J. Tobin⁷  Aleksandr Kuchmizhak⁸  Yoshiaki Nishijima^1,10 

[1] Centre for NEMS and Nanophotonics (CNNP), Department of Electrical Engineering, Indian Institute of Technology Madras;Centre for Micro-Photonics, Faculty of Science, Engineering and Technology, Swinburne University of Technology;Melbourne Centre for Nanofabrication;Institute of Advanced Sciences, Yokohama National University;Tokyo Tech World Research Hub Initiative (WRHI), School of Materials and Chemical Technology, Tokyo Institute of Technology;Physics Department, Yokohama National University;Infrared Microspectroscopy Beamline;Institute of Automation and Control Processes, Far Eastern Branch, Russian Academy of Sciences;Far Eastern Federal University;Department of Electrical and Computer Engineering, Graduate School of Engineering, Yokohama National University

关键词: metasurface;    vortex beam;    mid-infrared;    terahertz;    micro-optics;    IR imaging;   

DOI  :  10.1515/nanoph-2019-0112

学科分类：社会科学、人文和艺术（综合）

来源: De Gruyter

【 摘 要 】

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.

【 授权许可】

CC BY