Fig. 1. Schematical shown of the loss-assisted phase shift mechanism. (a) The structure configuration used in our work; (b) FDTD simulation result of the π phase shift come from the monolayer MoS₂ sheet

Fig. 2. (a) The optical image; (b) SEM image; (c) Raman mapping image of the atomical thin Fresnel zone plate fabricated by laser scribing technique

Fig. 3. Schematic diagram of the optical characterization system

Fig. 4. The focusing property in 535 nm wavelength of the monolayer Fresnel zone plate. (a) Experimental measured intensity distribution in the focal plane of z=43 μm; (b) Intensity line profile of the focal spot; (c) The experimental measured intensity distribution along the propagation distance in the region between z=30 μm and z=50 μm

Fig. 5. Broadband response of the phase modulation property of the 2D MoS₂ sheet. (a) The real and imaginary parts of the refractive index of the MoS₂ sheet; (b) The dependence of phase modulation property with the thickness of MoS₂ sheet. The shadow region represents the phase modulation region above 0.2π

Fig. 6. Simulation results of the broadband focusing properties. (a) Intensity profile along the optical axis for the wavelength region from 415 nm to 635 nm; (b) The dependence between the focal spot size with working wavelength

Fig. 7. Measured broadband focusing property of the atomic thin planar diffractive lens. Scalebar: 1000 nm