  The methodology of stochastic description for dissipation, a generic scheme
to decouple the interaction between two subsystems, is applied to the study of
dissipative dynamics in quantum optics. It is shown that the influence of the
coupled thermal or vacuum field on the quantum mode can be exactly represented
by the induced stochastic fields. The quantum mode thereby satisfies a
stochastic differential equation and dissipation effect due to the coupling
with the environment is obtained through statistical averaging. Within the
framework of stochastic description, it is demonstrated how to derive the
master equation for a single optical mode interacting with the bosonic bath. A
numerical algorithm for solving the master equation in which the coefficients
are determined by a set of integral equations is discussed and a comparison
with the known results is displayed. The derivation of the master equation for
the spontaneous decay of two-state atoms in the vacuum is also presented.
