  We address the properties of optical solitons that form in media with
competing cubic-quintic nonlinearity and parity-time(PT)-symmetric
complex-valued external potentials. The model describes the propagation of
solitons in nonlinear optical waveguides with balanced gain and loss. We study
the existence, stability, and robustness of fundamental, dipole, and multipole
stationary solutions in this PT-symmetric system. The corresponding eigenvalue
spectra diagrams for fundamental, dipole, tripole, and quadrupole solitons are
presented. We show that the eigenvalue spectra diagrams for fundamental and
dipole solitons merge at a coalescence point Wc1, whereas the corresponding
diagrams for tripole and quadrupole solitons merge at a larger coalescence
point Wc2. Beyond these two merging points, i.e., when the gain-loss strength
parameter W0 exceeds the corresponding coalescence points, the eigenvalue
spectra cease to exist. The stability of the stationary solutions is
investigated by performing the linear stability analysis and the robustness to
propagation of these stationary solutions is checked by using direct numerical
simulations.
