  The future laser interferometric gravitational-wave detectors sensitivity can
be improved using squeezed light. In particular, recently a scheme which uses
the optical field with frequency dependent squeeze factor, prepared by means of
a relatively short (~30 m) amplitude filter cavity, was proposed
\cite{Corbitt2004-3}. Here we consider an improved version of this scheme,
which allows to further reduce the quantum noise by exploiting the quantum
entanglement between the optical fields at the filter cavity two ports.
