808 research outputs found
Perfect optomechanically induced transparency in two-cavity optomechanics
Here, we study the controllable optical responses in a two-cavity
optomechanical system, especially on the optomechanically
induced transparency (OMIT) in the model which has never been studied before.
The results show that the perfect OMIT can still occur even with a large
mechanical damping rate, and at the perfect transparency window the long-lived
slow light can be achieved. In addition, we find that the conversion between
the perfect OMIT and optomechanically induced absorption can be easily achieved
just by adjusting the driving field strength of the second cavity. We believe
that the results can be used to control optical transmission in modern optical
networks.Comment: 8 pages, 9 figure
A Real-time Range Finding System with Binocular Stereo Vision
To acquire range information for mobile robots, a TMS320DM642 DSP-based range finding system with binocular stereo vision is proposed. Firstly, paired images of the target are captured and a Gaussian filter, as well as improved Sobel kernels, are achieved. Secondly, a feature-based local stereo matching algorithm is performed so that the space location of the target can be determined. Finally, in order to improve the reliability and robustness of the stereo matching algorithm under complex conditions, the confidence filter and the left-right consistency filter are investigated to eliminate the mismatching points. In addition, the range finding algorithm is implemented in the DSP/BIOS operating system to gain real-time control. Experimental results show that the average accuracy of range finding is more than 99% for measuring single-point distances equal to 120cm in the simple scenario and the algorithm takes about 39ms for ranging a time in a complex scenario. The effectivity, as well as the feasibility, of the proposed range finding system are verified
2-tert-Butyl-6-[(4-chloro-2-nitroÂphenÂyl)diazenÂyl]-4-methylphenol
In the title compound, C17H18ClN3O3, the dihedral angle between the planes of the two benzene rings is 1.03 (7)°. The overall conformation of the molÂecule is influenced, in part, by electron delocalization and by an intraÂmolecular bifurcated O—H⋯(O,N) hydrogen bonds. The O atoms of the nitro group, one of which serves as an H bond acceptor, are disordered over two sets of sites with refined occupancies of 0.56 (3) and 0.44 (3)
Berry connection polarizability tensor and third-order Hall effect
One big achievement in modern condensed matter physics is the recognition of
the importance of various band geometric quantities in physical effects. As
prominent examples, Berry curvature and Berry curvature dipole are connected to
the linear and the second-order Hall effects, respectively. Here, we show that
the Berry connection polarizability (BCP) tensor, as another intrinsic band
geometric quantity, plays a key role in the third-order Hall effect. Based on
the extended semiclassical formalism, we develop a theory for the third-order
charge transport and derive explicit formulas for the third-order conductivity.
Our theory is applied to the two-dimensional (2D) Dirac model to investigate
the essential features of BCP and the third-order Hall response. We further
demonstrate the combination of our theory with the first-principles
calculations to study a concrete material system, the monolayer FeSe. Our work
establishes a foundation for the study of third-order transport effects, and
reveals the third-order Hall effect as a tool for characterizing a large class
of materials and for probing the BCP in band structure.Comment: 7 pages, 4 figure
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