Squeezed vacuum pulse generation by χ(3) Nonlinearity in a quasi-phase-matched PPLN and a short fibre

Squeezed vacuum (SV) generation through third-order optical nonlinearity chi⁽³⁾ is useful for generating a quantum entanglement pair based on continuous variable. However, third-order nonlinearity is usually small. Therefore, the typical interaction length should be large and ultrashort laser pulses should be used. Then, it becomes important to avoid excess phase noise, especially guided-acoustic-wave Brillouin scattering (GAWBS) in optical fibres. In fact, so far, GAWBS has been preventing from generating SV pulses at sufficiently high squeezing levels. In this paper, we examine insusceptible chi⁽³⁾ squeezing to GAWBS.