Lasing in powdered ZnO: current state of affairs

Short review of the investigations of lasing in randomly inhomogeneous media in particular of lasing in powdered ZnO under picosecond pumping is given. Since the intrinsic lifetime of spontaneous UV emission in zinc oxide is less than 200 ps it is of interest to obtain stimulated UV radiation of powdered ZnO with pumping by pulses of nanosecond duration. This will clarify the possibility of quasi-continuous lasing in disordered media. In future this can open the way for working out a cathodoluminescent screen with narrow spectrum and short persistence time. Investigations of UV spectra of different powders of ZnO were conducted. In some of the samples investigated a narrowing of the UV band was observed with a rise of the pumping energy. At the same time a number of irregular narrow spikes appears on this band. The threshold density of pumping energy for appearance of this effect lies, depending on the sample, in the range of 2.7-27 mJ/cm².