Dynamics in a low-temperature glass: Fast generation and detection of optical holes

Abstract

High-resolution, fast optical hole-burning results are reported for the amorphous system 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−1 ), shallow (∼1%) holes 10 μs to 50 ms after their generation. The technique is described in detail along with careful tests demonstrating the validity of its results. The hole width is observed to increase linearly with time when plotted against log time. Using the four time correlation function description of optical hole burning, the time-dependent increase in hole width (spectral diffusion) is shown to arise from a broad distribution of fluctuation rates in the glass with the probability of having a fluctuation at rate R proportional to 1/R. The 10 μs to 50 ms data is combined with hole-width data spanning the range 100 ms to 10 000 s and with two-pulse picosecond photon echo data. The two-pulse photon echo linewidth is calculated by extrapolating the fluctuation rate distribution obtained from the hole-width data to short times. The results are in excellent agreement with experimental echo results. The combined data from the two sets of hole-burning experiments provides a detailed description of the glass dynamics over nine decades of time, 10 000 s to 10 μs. Together with the two-pulse photon echo results, the data provide information on the glass dynamical behavior over seven decades faster in time as well. The net result is a description of the dynamics in low-temperature ethanol glass on time scales spanning 16 decades.