Dispersionless polaritons on a twist boundary in optically uniaxial crystals

Abstract

It has been shown that the so-called dispersionless localized waves (polaritons) can exist in a bicrystal formed by two identical crystals. The optical axes of these crystals lie at the interface at a certain angle to one another. The exact analytic expression is derived for the velocity of the wave propagating along the bisector of the angle between the optical axes in the upper and the lower parts of the bicrystal. The wave structure is analyzed for several limiting cases.