  We show that nonlinear dynamics in diode lasers with optical injection leads
to frequency tunable microwave sidebands which are suitable for atomic physics
experiments. We demonstrate the applicability of the sidebands in an experiment
where rubidium atoms are magneto-optically trapped with both the trap and the
re-pump optical frequencies derived from one optically injected laser. We find
linewidth narrowing in the optical spectrum of the injected laser at both the
injection frequency and the sideband frequency. With strong optical injection
which leads to frequency locking we find a complete linewidth transfer from the
master to the slave. Further applications are discussed.
