Characterization of nonclassical properties of quantum states generated in an optical parametric amplifier This thesis concerns the generation of quantum states and the characterization of their nonclassical properties. Therefore an experimental technique to generate squeezed vacuum and coherently displaced squeezed states is presented. In order to characterize nonclassical states a new experimental technique the homodyne cross correlation measurement was realized showing a so far unknown insight into the quantumness of a squeezed state. Also an experimentally accessible witnessing approach for the degree of nonclassicality is presented for arbitrary quantum states.<eng>