Plasmonic photon sorters for spectral and polarimetric imaging

Colour cameras mimic the human eye and record only a small part of the information contained in the incoming light. Modern image sensing techniques, which subdivide the light spectrally or record information about the polarization of the incoming light, can extract much more information for applications ranging from biological studies to remote sensing(1-5). Spectral imaging techniques(6) typically rely on filters or interferometers combined with scanning or subsampling to record a spectral image 'cube' ( which has wavelength as a third dimension). This leads to inefficient use of the incoming light and/ or long recording times. Here, we show that surface plasmons enable direct recording of spectral image cubes in a single exposure. By texturing metal surfaces at the nanometre scale, incoming light is converted to surface plasmons and can then be separated according to wavelength and polarization, before being recoupled to light through subwavelength apertures that illuminate individual photodetector elements. This photon- sorting capability provides a new approach for spectral and polarimetric imaging with extremely compact device archictures.