Fig. 1

A photon sorting, metafilm device that leverages anti-Hermitian coupling. a Schematic view of an anti-Hermitian metafilm composed of differently sized semiconductor nanobeams (red and blue). The geometric properties of the nanobeams are chosen to elicit an anti-Hermitian coupling that facilitates sorting of incident photons by wavelength and subsequent photocurrent extraction. b Cross-sectional SEM image of a fabricated device structure. Left inset shows the TEM image of a repeating unit cell of the metafilm with electrically insulated Si beams (light) embedded in an Ag film (dark). Right inset shows an EDX line scan along the red dashed line in the TEM image. Scale bar, 500 nm. c Simulated absorption spectrums of anti-Hermitian coupled metafilm under TM-polarized illumination with the electric field oriented along the nanobeam axes. The simulated absorption spectrums for the 80-nm-wide (blue curve) and 60-nm-wide nanobeams (red curve) show how the device efficiently sorts photons with a narrow spectral separation of 30 nm. The total absorption in Si material (black dashed line) reaches a near-unity value. Three vertical lines indicate wavelengths of interests at which electric field maps are shown in d (blue line), e (red line), and f (black line). d, e Simulated images of the total electric field with superposed power flow lines at the wavelengths of 595 nm d and 625 nm e showing that Mie-like resonances are excited selectively in narrow(/wide) beams at shorter(/longer) illumination wavelengths. f Simulated image of scattered electric field at the wavelength of 605 nm showing that the differently sized beams scatter light with a π phase difference