  We demonstrate an all-optical $^{133}$Cs scalar magnetometer, operating in
nonzero magnetic field,in which the magnetic resonance is driven by an
effective oscillating magnetic field provided by the AC Stark shift of an
intensity-modulated laser beam. We achieve a projected shot-noise-limited
sensitivity of 1.7 fT/Hz$^{1/2}$ and measure a technical noise floor of 40
fT/Hz$^{1/2}$. These results are essentially identical to a coil-driven scalar
magnetometer using the same setup. This all-optical scheme offers advantages
over traditional coil-driven magnetometers for use in arrays and in
magnetically sensitive fundamental physics experiments e.g., searches for a
permanent electric dipole moment of the neutron.
