In this Letter, the loss and gain characteristics of an unconventional InxGa1-xAs∕Ga As asymmetrical step well structure consisting of variable indium contents of InxGa1-xAs materials are measured and analyzed for th...In this Letter, the loss and gain characteristics of an unconventional InxGa1-xAs∕Ga As asymmetrical step well structure consisting of variable indium contents of InxGa1-xAs materials are measured and analyzed for the first time, to the best of our knowledge. This special well structure is formed based on the indium-rich effect from the material growth process. The loss and gain are obtained by optical pumping and photoluminescence（PL）spectrum measurement at dual facets of an edge-emitting device. Unlike conventional quasi-rectangle wells, the asymmetrical step well may lead to a hybrid strain configuration containing both compressive and tensile strains and, thus, special loss and gain characteristics. The results will be very helpful in the development of multiple wavelength In Ga As-based semiconductor lasers.展开更多
In this paper,the effects of surface roughness on tornado-like vortices are studied in the laboratory for simulating tornado vortex at the Disaster Prevention Research Institute,Kyoto University,Japan. In the experime...In this paper,the effects of surface roughness on tornado-like vortices are studied in the laboratory for simulating tornado vortex at the Disaster Prevention Research Institute,Kyoto University,Japan. In the experiments,the distribution of the horizontal wind speed and direction at five different heights were measured with a hot-wire anemometer and a mini-vane.The characteristics of wind speed and direc- tion distribution for the tornado vortex on the various rough surfaces were first revealed with the simulative method in laboratory.By changing the swirl ratio(S=tanθ/2a)of simulation device,it is found that,the size of tornado-like vortex core will become almost identical,as the swirl ratio S exceeds a certain value (S>1.5). The experimental results can be used not only to explain the observed facts in the atmosphere but also to provide the experimental bases for some theoretical studies.展开更多
基金supported by the National Natural Science Foundation of China under Grant Nos.61376067 and61474118
文摘In this Letter, the loss and gain characteristics of an unconventional InxGa1-xAs∕Ga As asymmetrical step well structure consisting of variable indium contents of InxGa1-xAs materials are measured and analyzed for the first time, to the best of our knowledge. This special well structure is formed based on the indium-rich effect from the material growth process. The loss and gain are obtained by optical pumping and photoluminescence（PL）spectrum measurement at dual facets of an edge-emitting device. Unlike conventional quasi-rectangle wells, the asymmetrical step well may lead to a hybrid strain configuration containing both compressive and tensile strains and, thus, special loss and gain characteristics. The results will be very helpful in the development of multiple wavelength In Ga As-based semiconductor lasers.
文摘In this paper,the effects of surface roughness on tornado-like vortices are studied in the laboratory for simulating tornado vortex at the Disaster Prevention Research Institute,Kyoto University,Japan. In the experiments,the distribution of the horizontal wind speed and direction at five different heights were measured with a hot-wire anemometer and a mini-vane.The characteristics of wind speed and direc- tion distribution for the tornado vortex on the various rough surfaces were first revealed with the simulative method in laboratory.By changing the swirl ratio(S=tanθ/2a)of simulation device,it is found that,the size of tornado-like vortex core will become almost identical,as the swirl ratio S exceeds a certain value (S>1.5). The experimental results can be used not only to explain the observed facts in the atmosphere but also to provide the experimental bases for some theoretical studies.
