ZnO–ZnMgO Multiple Quantum-Well Ridge Waveguide Lasers

ZnO-ZnMgO multiple quantum-well (MQW) thin-film waveguides with ridge structures have been fabricated on quartz substrates. Low-temperature deposition of high-quality ZnO-ZnMgO MQW thin films was achieved by filtered cathodic vacuum arc technique. A ridge is defined on the thin film by plasma etching. Room-temperature lasing with a peak wavelength at 378 nm of 1.5-nm well width was observed under 355-nm optical excitation. Exciton-exciton scattering was attributed to the amplified spontaneous emission observed from the MQW waveguide. The net optical gain can be larger than 80 cm^-1 at a pump intensity of 2 MW/cm² .