Luminescence Delay and Determination of Nonradiative Relaxation Times

Oleg D. Asenchik, Vladimir V. Mogilny

F. A. Popp, Y. Yan

V. V. Khizhniakov, Inna Rebane

Antonio S. Seas, Vladimir Petricevic, Robert R. Alfano

The gain dynamics of photoexcited chromium-doped forsterite (Cr4+:Mg2SiO4) were measured by means of a pulsed excite-and-probe technique. The nonradiative relaxation time within the 3T2 vibronic state was determined by measuring the change in the induced gain of the probe pulse as a function of the pumpprobe delay. A 30 ps, 1.064 m pulse from a mode-locked Nd:YAG laser was split into two beams. The first beam provided the pump pulse to populate the 3T2 manifold. The other beam was focused in a calcite crystal to generate a 1.2 m probe pulse by means of stimulated Raman scattering. The transient gain was determined from the measured ratio of the transmitted probe intensity for unpumped and pumped cases as a function of the pumpprobe delay. The rise time (time for growth of the gain from 10% to 90%) was calculated to be 50 ps. A rate-equation analysis of population in the various states was used to extract a value for the vibrational relaxation time from the experimental data under the assumption of Gaussian pump and probe pulses. The best fit to the experimental data of gain as a function of time yields a value of 10 5 ps for the intra-3T2-state vibrational relaxation time.

V. V. Antonov‐Romanovskii

Liu Birui

Unlike conventional three-level GSA/ESA upconversion system,a four-level GSA/ESA upconversion system containing a nonradiative process is presented.The dynamic process and luminescent properties of the upconversion are analyzed theoretically by rate equation model.The results show that the rise process of the upconversion is dominated by the nonradiative relaxation rate of the middle nonradiative level,while the decay process is mainly governed by the relaxation rate of the final excited state level.