Spatial and temporal study of the 29 cm-1 phonon bottleneck in ruby using a PICOLO detector

Abstract

An enhanced PICOLO (Phonon Induced COherence LOss) technique has been used to study the dynamics of 29 cm-1 phonons in ruby generated by the direct optical pumping of the 2A¯(2E) level for a large range of excitation densities (bottleneck factorsb = 0.15–40) and an applied magnetic field of 600 G parallel or perpendicular to thec-axis. Particularly strong nonexponential decay of the phonon occupation numberp down top ≈ 0.003 was observed forH ⊥c and is explained by “incoherent bleaching” of the scattering medium (effective for highp) and enhanced spectral diffusion due to transverse relaxation of the phonon transition (for lowp). An explicit computer simulation that takes account of the full nonlinear spectral/spatial behavior of the coupled phonon/spin system is in excellent agreement with the experiments.