Colossal Birefringence from Periodic Structural Modulations

We introduce structural modulation as a new mechanism for achieving colossal optical anisotropy. Modulated nonstoichiometric material Sr
9/8
TiS
3
is shown to have an extraordinary refractive index n
e
= 4.5 and ordinary refractive index n
o
= 2.4 in the mid-infrared range.