In the resonance-tuned case, the phase modulation of the input carrier field creates equal magnitude sideband fields as
discussed in Section 2.2.2, and these sideband fields are transmitted to the output port thanks to Schnupp asymmetry in the
same state, i.e., they remain equal in magnitude and reside in the phase quadrature. In detuned configurations of GW
interferometers, the upper and lower RF-sideband fields are transformed differently, which influences both their amplitudes and
phases at the readout port.