Flourescence-line-narrowing and Monte Carlo studies of spectral transport of nonequilibrium phonons in ruby

Abstract

Fluorescence line narrowing (FLN) in the three-level scheme 4A2-E(2E)-2A(2E) is used to probe, with high resolution, the spectrum of nonequilibrium 29 cm-1 phonons in near resonance with the E(2E)-2A(2E) transition in ruby following injection with a heater. The shape of the 29 cm-1 phonon spectrum is found to change dramatically with time due to frequency-dependent imprisonment and spectral transport. The development of the phonon spectrum is reproduced by Monte Carlo simulations following the itinerary of a phonon. The simulations explicitly take into account inelastic scattering as a result of one-site resonant Roman scattering by optically excited exchange-coupled Cr3+ pairs until escape out of the optically pumped zone.