SYSTEM CONTROL BY VARIATION OF THE SQUEEZING PHASE

We analyze the spectrum of squeezing of the beam reflected by a one-ended empty cavity, treating separately the two cases in which the input corresponds to a squeezed vacuum, or to a squeezed beam with a mean value much larger than the fluctuations. In the first case the fluctuation ellipse can be rotated al will by varying the cavity length. In the second case the relative angle between the fluctuation ellipse and the mean value can be rotated arbitrarily only out of a frequency band with a width on the order of the cavity linewidth: in such a way phase squeezing can be converted into amplitude squeezing and vice versa. This circumstance makes it possible to detect the phase sensitivity of a squeezed state without any local oscillator, by simply measuring the intensity fluctuations.