High-pressure low-temperature optical dephasing of rhodamine 101 in PMMA

High pressure (0–30 kbar) is used to investigate the effect of increased density on the temperature-dependent optical dephasing of rhodamine 101 (Rh101) in polymethyl methacrylate (PMMA). Photon echo measurements have been performed on Rh101-doped PMMA at temperatures between 1.2 and 2.1 K at pressures up to 30 kbar. The 20% volume compression at 30 kbar resulted in little change in either the magnitude or the temperature dependence of the optical dephasing rate. The pressure insensitive homogeneous linewidth Γ = 110 T1.35 MHz is discussed in terms of the two level system model often used to characterize the optical dynamics of glasses.