  Millimetre-wave observations represent an important tool for Cosmology
studies. The Line Intensity Mapping (LIM) technique has been proposed to map in
three dimensions the specific intensity due to line (e.g. [CII], CO) emission,
for example from the primordial galaxies, as a function of redshift.
Hyper-spectral integrated devices have the potential to replace the current
Fourier transform, or the planned Fabry-Perot-based instruments operating at
millimetre and sub-millimetre wavelengths. The aim is to perform hyper-spectral
mapping, with a spectral resolution R= 100-1000, over large, i.e. thousands of
beams, instantaneous patches of the Sky. The innovative integrated device that
we have developed allows avoiding moving parts, complicated and/or dispersive
optics or tunable filters to be operated at cryogenic temperatures. The
prototype hyper-spectral focal plane is sensitive in the 75-90GHz range and
contains nineteen horns for sixteen spectral-imaging channels, each selecting a
frequency band of about 0.1GHz. For each channel a conical horn antenna,
coupled to a planar superconducting resonant absorber made of thin aluminium,
collects the radiation. A capacitively coupled titanium-aluminium bilayer
Lumped Element Kinetic Inductance Detector (LEKID) is then in charge of
dissipating and sensing the super-current established in the resonant absorber.
The prototype is fabricated with only two photo-lithography steps over a
commercial mono-crystalline sapphire substrate. It exhibits a spectral
resolution of about 800. The optical noise equivalent power of the best
channels is in the observational relevant 4E-17W/sqrt(Hz) range. The average
sensitivity of all the channels is around 1E-16W/sqrt(Hz). The device, as
expected from 3-D simulations, is polarisation-sensitive, paving the way to
spectro-polarimetry measurements over very large instantaneous field-of-views.
