Fig. 3: Free-space optical modulation via electrostatic gating of a hybrid-2D metasurface.
From: Electrically tunable strong coupling in a hybrid-2D excitonic metasurface for optical modulation
a Optical microscope image of the hybrid-2D metasurface: a heterostructure comprised of monolayer WS2 (blue) encapsulated by bottom (purple) and top (green) hBN layers is placed on a gold back-reflector, which doubles as the gate electrode (VG), and integrated with a dielectric grating (white, dashed). The red star indicates the position of the b atomic force micrograph (top) and horizontal cross-section through the center (bottom). Scalebar: 500 nm. c Experimental back-focal plane imaging spectroscopy of the angular dispersion at strong n-type doping (+25 V, red) and d intrinsic doping (−25 V, blue), with the latter exhibiting a Rabi splitting energy of ΩR = 36.0 meV. e Normal-incidence TE-polarized reflectance spectra extracted from (c) and (d) at kx/k0 = 0, with a maximum reflectance contrast of 48.9% at λ0 = 627.5 nm indicated. f Modulation depth obtained from the spectra in (e), revealing 9.9 dB peak signal modulation at λ0 = 620.5 nm
