Effects of Correlations Between the Real and Imaginary Partsof Quantum Noise on Intensity Fluctuation for a Single-Mode Laser

We study the effects of correlations between the real and imaginary parts of quantum noise on the intensity fluctuation for a single-mode laser. The analytic expressions of the intensity correlation function C(τ) and the associated relaxation time T_c in the case of a stable locked phase resulting from the cross-correlation λ_q between the real and imaginary parts of quantum noise are derived by means of projection operator method. Based on numerical computations it is found that the presence of cross-correlations between the real and imaginary parts of quantum noise causes the intensity fluctuation to increase. A slowing-down phenomenon exists in the sense that T_c increases as a function of |λ_q|. Thus the decay of intensity fluctuation becomes slower.