Abstract
Terahertz (THz) dielectric responce of lithium niobate crystals has been studied by THz Time-Domain Spectroscopy. The complex dielectric constants εz(ω) and εy(ω) have been determined from 0.1 THz to 2.0 THz without the Kramers-Kronig Analysis. The dispersion relations of A1(z) and E(y) symmetry phonon-polaritons have been determined accurately down to 0.1 THz.