Abstract:By using the linear approximation method,the normalized mean intensity fluctuation C(0) and power spectrum S(ω) in single-mode laser loss model were calculated after inputting a biased amplitude modulation signal. The change rules of C(0) were obtained when the amplitude of carrier signalB,the carrier signal frequency with high frequency ω and the intensity of quantum noise Q varied. It is found that the C(0) decreases when the carrier signal frequency with low frequency Ω becomes large,ω becomes smaller,cross-correlation λq between the real and imaginary part of the quantum noise becomes stronger or B is away from the threshold. The change rules of the power spectrum S(ω) with the parametera0/A,the modulation signal of low frequency Ω,the carrier signal of high frequency ω and correlation coefficient λq between the real and imaginary part of quantum noise were studied,but there exists some special phenomena.