Low-loss and directional output ZnO thin-film ridge waveguide random lasers with MgO capped layer

Room-temperature ultraviolet lasing characteristics of ZnO thin-film ridge-waveguide random lasers with MgO capped layer fabricated on n-type (100) Si substrate are reported. It is demonstrated that highly directional emission from the facets of the random lasers can be achieved. Reduction of scattering loss inside the random cavities can also be obtained. In addition, the improvement in the efficiency of the lasing characteristics of the random lasers by optical feedback is studied.