In a hot sodium atomic vapor, we report the observation of electromagnetically induced polarization rotation (EIPR) in the 3S 1∕2 -3P 1∕2 -4D 3∕2 and 3S 1∕2 -3P 3∕2 -4D 3∕2;5∕2 three-level ladder transitions, where a weak probe beam and a strong coupling beam are resonant to the lower and the upper transition, respectively. The EIPR spectra exhibited a unique double-dispersion feature, which was more pronounced for the higher coupling powers. The maximum rotation angle was 18 deg. Optical switch experiment based on EIPR gave a fast response time of less than 100 ns.

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