  A driven opto-RF oscillator, consisting of a dual-frequency laser (DFL)
submitted to frequency-shifted feedback, is studied experimentally and
numerically in a chaotic regime. Precise control of the reinjection strength
and detuning permits to isolate a parameter region of bounded-phase chaos,
where the opto-RF oscillator is frequency-locked to the master oscillator, in
spite of chaotic phase and intensity oscillations. Robust experimental evidence
of this synchronization regime is found and phase noise spectra allows to
compare phase-locking and bounded-phase chaos regimes. In particular, it is
found that the long-term phase stability of the master oscillator is well
transferred to the opto-RF oscillator even in the chaotic regime.
