  We study nonlinear optical effects in the laser excitation of Rydberg states.
$5S_{1/2}$ and $5P_{3/2}$ levels of $^{85}$Rb are strongly coupled by a strong
laser field and probed by a weak laser tuned to the $5P_{3/2} - 44D$ Rydberg
resonance. We observe high contrast Autler-Townes spectra which are dependent
on the pump polarization, intensity and detuning. The observed behavior agrees
with calculations, which include the effect of optical pumping.
