Random Lasing in ZnSe and CdSe Semiconductor Powders

Abstract

Random lasing determines the effect of light generating in highly disordered scattering gain media and was firstly theoretically predicted by V.S. Letokhov in 1967 (Letokhov, JETP Lett 5:212–215, 1967). The feedback in random lasers is based on randomly appearing gain loops between neighbouring active particles of scattering media. The materials which are considered to produce random lasing are A II B VI semiconductor powders (Cao, Waves Random Media 13:R1–R39, 2003; Takahashi et al, Opt Lett 34:3923–3925, 2009) and vertically aligned nanowires (Chen at al, Excitonic properties and near-infrared coherent random lasing in vertically aligned CdSe nanowires. Adv Mater (Deerfield Beach, Fla.) 23:1404–1408, 2011) and laser dye solutions containing scattering nanoparticles (Cao, Waves Random Media 13:R1–R39, 2003). In the present work, random lasing in the visible spectra is obtained in ZnSe (475 nm) and CdSe (735 nm) wide bandgap semiconductor microcrystalline powders. A dramatic intensity increasing, spectrum shortening and a structure appearance were observed in ZnSe and CdSe powders with the crystalline size of about 1 μm in diameter after exceeding the threshold excitation intensity. The lasing is due to the emergence of feedback through the formation of random gain loops between the active particles of the scattering medium. Random lasing threshold in the micron sized ZnSe active powder particles is 620 kW/cm2 that is lower than in work (Takahashi et al, Opt Lett 34:3923–3925, 2009). Random lasing in CdSe powder was obtained for the first time with the threshold excitation intensity 480 kW/cm2. The key feature of random lasers is low cost of its production (no complex cavity is needed) and possibility to be deposited on any type of surface. Described lasers can find their applications in visualization systems and lighting technology (Cao, Waves Random Media 13:R1–R39, 2003), in data transmission, in medicine as biosensors and in identification systems “friend or foe” (Dubois and Rochelle, Active cooperative tuned identification friend or foe (actiff). US Patent 5,966,227, 12 Oct 1999).