Whispering gallery mode lasing in zinc oxide microwires

Lasing on whispering gallery modes was excited by optical pumping in single zinc oxide microwires fabricated by a simple carbothermal evaporation process. The experimentally observed laser modes agree precisely with the predicted energetic positions obtained from a plane wave model. Systematic diameter dependent measurements have been carried out for diameters of the microwires between 3 and 12 mu m. The investigated microlasers are found to have a lasing threshold of about 170 kW/cm(2) at 10 K.