A spectral route to determining chirality

We show how one-dimensional structured media can be used to measure chirality, via the spectral shift of the photonic band gap edges. Analytically, we show that a chiral contrast can, in some cases, be mapped unto an index contrast, thereby greatly simplifying the analysis of such structures. Using this mapping, we derive a first-order shift of the band gap edges with chirality.

Potentially, this effect could be used for measuring enantiomeric excess.