Demonstration of an ultraviolet ZnO-based optically pumped third order distributed feedback laser

The authors demonstrate an optically pumped ZnO distributed feedback laser operating at 383 nm. For a large temperature range between 10 and 270 K, the device lased in a single longitudinal mode. Mode selection was accomplished via a third order diffraction grating, which was dry etched into a 120 nm thick Si₃N₄ layer deposited on the ZnO active region. They observed a spectral linewidth of 0.4 nm, a pump threshold intensity of 0.12 MW/cm², and a peak output power of 14 mW. From wavelength versus temperature measurements, they deduced a temperature tuning coefficient of the ZnO refractive index of 9×10−5 K⁻¹.