Guided Modes of Anisotropic van der Waals Materials Investigated by near-Field Scanning Optical Microscopy

• DOI: 10.1021/acsphotonics.7b01518
• Publication Date: 2018-01-27T14:31:17Z
• Authors: Daniel Wintz; Kundan Chaudhary; Ke Wang; Luis A. Jauregui; Antonio Ambrosio; Michele Tamagnone; Alexander Y. Zhu; Robert C. Devlin; Jesse D. Crossno; Kateryna Pistunova; Kenji Watanabe; Takashi Taniguchi; Philip Kim; Federico Capasso
• Keywords: Condensed Matter - Mesoscale and Nanoscale Physics; Mesoscale and Nanoscale Physics (cond-mat.mes-hall); FOS: Physical sciences; 02 engineering and technology; 0210 nano-technology; Physics - Optics; Optics (physics.optics); 3. Good health

Guided modes in anisotropic two-dimensional van der Waals materials are experimentally investigated and their refractive indices in visible wavelengths are extracted. Our method involves near-field scanning optical microscopy of waveguide (transverse electric) and surface plasmon polariton (transverse magnetic) modes in h-BN/SiO2/Si and Ag/h-BN stacks, respectively. We determine the dispersion of these modes and use this relationship to extract anisotropic refractive indices of h-BN flakes. In the wavelength interval 550-700 nm, the in-plane and out-of-plane refractive indices are in the range 1.98-2.12 and 1.45-2.12, respectively. Our approach of using near-field scanning optical microscopy allows for direct study of interaction between light and two-dimensional van der Waals materials and heterostructures.