Fig. 1. Optical properties of passive non-hermitian metasurfaces. (a) Biatomic PT symmetric metasurfaces. (b) Changes in eigenstates during the transition of the system from PT symmetry to broken PT symmetry^[20]. (c) Exceptional topological phase^[23]. (d) Perturbative structures in complex space separated from EP, tangent to EP, and surrounded by EP

Fig. 2. Passive non-hermitian metasurface devices for free-space optical transmission. (a) Schematic diagram of graphene metal resonant ring metasurface. (b) Exceptional point reflectance map^[28]. (c) Metasurface grating. (d) Relationship between polarized light reflectance and complex coefficient A^[29]. (e) Metasurface thin films. (f) Light absorption^[30].

Fig. 3. Passive non-Hermitian metasurfaces for waveguide transmission. (a) Non-Hermitian three waveguide. (b) Exceptional point distribution^[32]. (c) Loss-adjustable dual waveguide. (d) Asymmetric transmission^[34]

Fig. 4. Exceptional optical phenomena and device design based on passive non-Hermitian metasurfaces. (a) Asymmetric transmission sensitive to incidence direction^[36]. (b) Exceptional topological phase. (c) Angular asymmetric holography based on exceptional topological phase^[37]. (d) Angle-sensitive pulse transmission realized with EP structure^[39]. (e) Color vector holographic^[43]

Fig. 5. Experimental scheme for passive non-Hermitian metasurfaces. (a) Holographic experimental equipment^[52]. (b) Waveguide experimental equipment^[53].

Fig. 6. Complex exceptional optical phenomena. (a) Fermi arcs in the air gap^[57]. (b) Third-order EP^[60]. (c) Energy band spectrum at periodic boundary. (d) Energy band spectrum with open boundary^[62]. (e) Floquet topological photonic lattice models. (f) Skin effect^[67]