A comprehensive study of impulse pumping of Ti:Sapphire by AlInGaN LEDs

LEDs operating under high pulsed current density, which excludes self-heating, are of great interest for different applications, in particular, for pumping lasers with a short time of activator relaxation, such as Ti:Sapphire. The current dependences of the efficiency emission spectra as well as the rise and fall times of high-power blue and green LEDs were investigated under extremely high pulse current density up to 7 kA/cm² and a pulse duration of 100 ns to 3 μs. An analysis of the pulse behaviour of the LEDs reveals that the main droop in efficiency and a change in the spectrum occur up to the current densities ∼ 1 kA/cm² and seem to be non-thermal. The energy and spectral pulse characteristics of the radiation were studied with simultaneous recording the excited Ti:Sapphire photoluminescence in order to determine the optimal pumping conditions. (paper)