Fig. 4

a Experimental results of reflectance spectra with uniaxial strains (top), and the first-principles calculated reflectance spectrum with uniaxial strains (bottom). Arrows indicate the peak locations of the reflectance. Inset, optical image of the MoS₂ flake used for reflectance spectrum testing. b–c Optical images of the fabricated MoS₂-based grating on PDMS. d Schematic diagram of MoS₂-based grating stretched by translation stages. e Image of the first-order diffraction spot of the unstrained (top) and the strained (bottom) grating. White arrows indicate the intensity peak