Relation between the Relaxation of Intrinsic Stimulated Picosecond Emission from GaAs with a Characteristic Charge-Carrier Cooling Time

Resumo

During the powerful picosecond optical pumping of a thin (~1 μm) GaAs layer, a stimulated intense (up to 1 GW/cm²) picosecond emission arises. It is found that the characteristic picosecond relaxation time τ_r of the emission and of the carrier density increase with an increase of the diameter of the pump pulse for a fixed density of the pump-pulse energy. Due to the relation between the density and the temperature of carriers in the case of high-intensity emission (in the saturation state of emission amplification), the time τ_r is associated with the characteristic temperature-relaxation time τ_T of photopumped carriers, which was determined previously theoretically taking into account the emission-induced heating of carriers. The corresponding analytical expressions for τ_r as a function of τ_T are consistent with the above experimental results.