Within this thesis, an optical resonator is used to characterise the quantum state of a fs pulse squeezed in an optical fibre. The resonator separates the carrier pulse from the quantum state. The influences of the laser and the resonator's properties on this separation are investigated. Furthermore, the occurring Brillouin scattering on thermally excited vibrational modes of the fibre is examined. With the addition of a pulse shaper, the setup is enabled to experimentally access and measure complex correlation within the squeezed fs pulse.