  We report the measurements of the pseudodielectric function, far-infrared
reflectivity and Raman scattering spectra in Sr_{14}Cu_{24}O_{41} single
crystal. We study the lattice and the spin dynamics of the Cu$_2$O$_3$ spin
ladders and CuO$_2$ chains of this compound. The ellipsometric and the optical
reflectivity measurements yield the gap values of 1.4 eV, 1.86 eV, 2.34 eV (2.5
eV) for the ladders (chains) along the {\bf c}-axis and 2.4 eV along the {\bf
a}-axis. The electronic structure of the Cu$_2$O$_3$ ladders is analyzed using
tight-binding approach for the correlated electron systems. The correlation gap
value of 1.4 eV is calculated with the transfer energy (hopping) parameters
$t=t_{0}$=0.26 eV, along and perpendicular to legs, $t_{xy}$=0.026 eV
(interladder hopping) and U=2.1 eV, as a Coulomb repulsion. The optical
parameters of the infrared active phonons and plasmons are obtained by
oscillator fitting procedure of the reflectivity spectra. Raman scattering
spectra are measured at different temperatures using different laser line
energies. The two-magnon peak is observed at about 2880 cm$^{-1}$. At
temperatures below 150 K the new infrared and Raman modes appear due to the
charge ordering.
