  Sensing molecular chirality at the nanoscale has been a long-standing
challenge due to the inherently weak nature of chiroptical signals, and
nanophotonic approaches have proven fruitful in accessing these signals.
However, in most cases, absolute chiral sensing of the total chiral refractive
index has not been possible, while the strong inherent signals from the
nanostructures themselves obscure the weak chiroptical signals. Here, we
propose a dielectric metamaterial system that overcomes these limitations and
allows for absolute measurements of the total chirality, and the possibility
for a crucial signal reversal that enables chirality measurements without the
need for sample removal. As proof of principle, we demonstrate
signal-enhancements by a factor of 200 for ultrathin, sub-wavelength, chiral
samples over a uniform and accessible area.
