Experimental observation of the reduction of light group velocity by spectral burning hole in a ruby crystal

Slow light propagation is observed in solid state material at room temperature. Here we report the investigation of the slowdown of light propagation resulting from steep change of refractive index by spectral hole technique in a ruby crystal at room temperature. Measured delay is about 3.452±0.005 ms, corresponding to a group velocity as slow as 28.969±0.042 m/s in a nonsinusoid modulated waveform.