Bistability patterns and nonlinear switching with very high contrast ratio in a 1550 nm quantum dash semiconductor laser

We report on the experimental observation of optical bistability (OB) and nonlinear switching (NS) in a nanostructure laser; specifically a 1550 nm quantum dash Fabry-Perot laser subject to external optical injection and operated in reflection. Different shapes of optical bistability and nonlinear switching, anticlockwise and clockwise, with very high on-off contrast ratio (up to 180:1) between output states were experimentally measured. These results added to the potential of nanostructure lasers for enhanced performance offer promise for use in fast all-optical signal processing applications in optical networks. © 2012 American Institute of Physics

Kajian Pustaka Mengenai Restaurant Atmosphere

Restaurant is one of the businesses that support tourism development. Restaurants nowadays don't only provide food, but also the service and atmosphere to their customers. The purpose of this study is to discover theaspects defining restaurant atmosphere and the implications of restaurant atmosphere to other particular aspects related to restaurant business. This article is written based on a study conducted through a literature review. Through the examination, it is found that the atmosphere of a restaurant is one important aspect and can be considered as a competitive advantage as well as one of the determinants of customer satisfaction

The Co-evolution of Disk and Star in Embedded Stages: The Case of the Very Low-mass Protostar

We have observed the CCH (N=3-2, J=7/2-5/2, F=4-3 and 3-2) and SO (6_7-5_6) emission at a 0"2 angular resolution toward the low-mass Class 0 protostellar source IRAS 15398-3359 with ALMA. The CCH emission traces the infalling-rotating envelope near the protostar with the outflow cavity extended along the northeast-southwest axis. On the other hand, the SO emission has a compact distribution around the protostar. The CCH emission is relatively weak at the continuum peak position, while the SO emission has a sharp peak there. Although the maximum velocity shift of the CCH emission is about 1 km s^-1 from the systemic velocity, a velocity shift higher than 2 km s^{-1} is seen for the SO emission. This high velocity component is most likely associated with the Keplerian rotation around the protostar. The protostellar mass is estimated to be 0.007^{+0.004}_{-0.003} from the velocity profile of the SO emission. With this protostellar mass, the velocity structure of the CCH emission can be explained by the model of the infalling-rotating envelope, where the radius of the centrifugal barrier is estimated to be 40 au from the comparison with the model. The disk mass evaluated from the dust continuum emission by assuming the dust temperature of 20 K-100 K is 0.1-0.9 times the stellar mass, resulting in the Toomre Q parameter of 0.4-5. Hence, the disk structure may be partly unstable. All these results suggest that a rotationally-supported disk can be formed in the earliest stages of the protostellar evolution