Experimental Observation of Autler--Townes Splitting in Sub-Doppler Selective Reflection Spectroscopy

We present an experimental study of Autler--Townes splitting of non-linear selective reflection spectroscopy in a Λ-type driven three-level system. The sub-Doppler reflection spectroscopy is observed and the Autler--Townes splitting is measured as functions of the different coupling laser intensity and detuning. The coherent drive splits the excited state into two dressed states and an Autler-Townes splitting emerges in the probe reflection. The experimental results are in good agreement with theoretical fit.