Abstract: A semiconductor device which comprises a semiconductor substrate having a surface orientation substantially in a {100}-orientation is provided. On the semiconductor substrate, plural steps formed in a direction deviated substantially from a <110>-direction by 5 degrees or more are formed. The steps, which are mesa and concave portions, are buried by plural semiconductor crystal layers grown by the use of MOCVD or the like. A method of manufacturing such a device is also provided.

Abstract: A coaxial dielectric resonator for use at high frequency. The outer or inner peripheral surface of a tubular dielectric member is stepped so as to provide a greater suppression of spurious resonance. The dielectric member has a prism-shaped outer configuration so as to provide a high Q value, as well as improved space factor.

Abstract: An impurity-doped double-heterostructure semiconductor laser adapted for single-longitudinal-mode operation is disclosed which includes a semiconductive substrate and a mesa of double-heterostructure formed over the substrate. The mesa comprises an active layer serving as a light-emitting layer, a waveguiding layer adjacent to the active layer and clad layers interposing the active layer and the waveguiding layer therebetween. A high-resistively layer is formed to bury the lateral surfaces of the mesa. The active layer contains impurities of a rare earth element with a previously selected concentration.