64,537 research outputs found
Coherent optical control of polarization with a critical metasurface
We describe the mechanism by which a metamaterial surface can act as an ideal
phase-controlled rotatable linear polarizer. With equal-power linearly
polarized beams incident on each side of the surface, varying the relative
phase rotates the polarization angles of the output beams, while keeping the
polarization exactly linear. The explanation is based on coupled-mode theory
and the idea of coherent perfect absorption into auxiliary polarization
channels. The polarization-rotating behavior occurs at a critical point of the
coupled-mode theory, which can be associated with the exceptional point of a
parity-time (PT) symmetric effective Hamiltonian
Microscopic origin of light emission in Al_yGa_{1-y}N/GaN superlattice: Band profile and active site
We present first-principles calculations of AlGaN/GaN superlattice,
clarifying the microscopic origin of the light emission and revealing the
effect of local polarization within the quantum well. Profile of energy band
and distributions of electrons and holes demonstrate the existence of a main
active site in the well responsible for the main band-edge light emission. This
site appears at the position where the local polarization becomes zero. With
charge injection, the calculated optical spectra show that the broadening of
the band gap at the active site leads to the blueshift of emission wavelength
Synthetic vision and emotion calculation in intelligent virtual human modeling
The virtual human technique already can provide vivid and believable human behaviour in more and more scenarios. Virtual humans are expected to replace real humans in hazardous situations to undertake tests and feed back valuable information. This paper will introduce a virtual human with a novel collision-based synthetic vision, short-term memory model and a capability to implement the emotion calculation and decision making. The virtual character based on this model can ‘see’ what is in his field of view (FOV) and remember those objects. After that, a group of affective computing equations have been introduced. These equations have been implemented into a proposed emotion calculation process to enlighten emotion for virtual intelligent huma
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