Probing low temperature glass dynamics by fast generation and detection of optical holes

High resolution, fast optical hole burning results are reported for the amorphous ystem cresyl violet in ethanol glass at 1.3 K. Holes are burned and detected using a novel technique which allows precise detection of narrow (~0.03 cm- ’), shallow ( = 1%) holes IO us to 50 ms after their generation. The hole width is observed lo change linearly when plotted against log time. Using a four point correlation model of optical hole burning, this spectral diffusion is shown to arise from a 1 /R distribution offluctuation rates. The distribution extrapolates to the value of the two pulse photon echo linewidth measured on the same system. 1