The figure-eight fiber laser is considered in two configurations,
with either a unidirectional active ring cavity coupled
with a nonlinear optical loop mirror (NOLM) or a unidirectional
passive cavity and a nonlinear amplifying loop
mirror (NALM). In each case, we derive a master equation
of cubic complex Ginzburg Landau (CGL) type, in which
the coefficients explicitly depend on the characteristics of
the cavity. Single-pulse and continuous wave (cw) solutions
in both normal and anomalous dispersion are discussed analytically.