In this article we investigate the effects of cavity detuning on two quantu
m properties of the generated optical fields in cavity second harmonic gene
ration. These are the configuration of the error ellipse and the intensity
fluctuations of the fields, including the sum field of the two modes. The f
orm of the error ellipse is of topical interest due to recent work on quant
um tomography, which allows experimental measurement of the Wigner function
for light fields. We also investigate to what extent the decrease in quadr
ature squeezing with detuning can be attributed solely to the resulting dep
letion of the intra-cavity fields. (C) 1999 Elsevier Science B.V. All right
s reserved.