Stimulated emission and optical gain in PbSe quantum dot-doped liquid-core optical fiber based on multi-exciton state

We studied the properties of stimulated emission and optical gain of 4.4 nm PbSe quantum dot (QD)-doped liquid-core optical fiber based on multi-exciton state under strong pumping condition as a function of QD solution concentration, fiber length and pump power in order to establish the conditions to maximize stimulated emission intensities and optical gain. Auger recombination lifetime and internal quantum efficiency (IQE) were introduced in the multi-exciton model for calculation. Shifts of the spectral peak position were observed and explained in detail. The narrowing spectral half band width and the super linear intensity dependence of the output power with the pump accounted for the generation of stimulated emission. The maximal optical gain of ~30 dB was obtained which was larger than that of the single-exciton model under the same fiber parameters. Our interesting results might be useful in the design of optical fiber-based amplifiers and lasers.