  By investigating thoroughly the tunable behavior of coupled modes, we
highlight how it provides new means to handle the properties of spin transfer
nano-oscillators. We first demonstrate that the main features of the microwave
signal associated with coupled vortex dynamics i.e. frequency, spectral
coherence, critical current, mode localization, depends drastically on the
relative vortex core polarities. Secondly we report a large reduction of the
nonlinear linewidth broadening obtained by changing the effective damping
through the control of the core configuration. Such a level of control on the
nonlinear behavior reinforces our choice to exploit the microwave properties of
collective modes for applications of spintronic devices in novel generation of
integrated telecommunication devices.
