Entangled state generation and modulation of vacuum squeezing by classical optical fields in birefringent fibre

Evolution of the vacuum fluctuations in the two-wave mixing of the optical fields propagating in the birefringent fibre is studied. The two-wave mixing in the birefringent fibre has been suggested as a possible scheme for the entangled state generation. Our treatment to study the entangled state generation uses undepleted pump approximation and enables to trace influence of input conditions of the classical optical fields on evolution of the vacuum squeezing. We report the periodical modulation of the vacuum squeezing when input relative phase of the coherent waves varies. Measure of nonclassical correlations imposed on the generated light is calculated.