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Recent explorations of topology in physical systems have led to a new paradigm of condensed matters characterized by topologically protected states and phase transition, for example, topologically protected photonic crystals enabled by magneto-optical effects. However, in other wave systems such as acoustics, topological states cannot be simply reproduced due to the absence of similar magnetics-related...
Recently PT symmetric devices, a new class of artificial optical materials, found a tremendous interest in research where PT symmetry is maintained by balancing gain and loss regions, and therefore combined PT operation leads to interchange loss and gain and leaves the system invariant. Based on this gain/loss modulation concept, we demonstrate both experimentally and theoretically a PT symmetric...
In this paper we will report a novel CMP slurry chemistry which can provide tunable removal selectivity between various silicon-containing materials, such as SiGe, bare silicon, poly silicon or amorphous silicon against SiO2 and/or SiN. The slurry chemistry is a non-hydrogen peroxide based system containing a novel catalyst. By adjusting the amount of the catalyst, we can fine tune desirable removal...
According to Paul et al.'s model [1], behavior of CMP slurry abrasives during polishing was modeled as an adsorption/desorption reaction on sites of polishing pad. The model showed a saturation relationship between removal rate and abrasive concentration. In this study, we extended this concept to include repulsive force between abrasives since it might result in reduction of effective sites on the...
As an important transportation phenomenon, Bloch oscillations have been studied extensively in Hermitian systems. Here by exploiting the concept of parity-time symmetry, we experimentally realize for the first time Bloch oscillations in a non-Hermitian silicon photonic lattice and show that such system contains intriguing physics.
We have designed, fabricated, and tested a CMOS compatible silicon waveguide system that demonstrates nonreciprocal light propagation on-chip, by mimicking microscopic non-Hermitian optical potentials for guided light and thus spontaneously breaking parity-time symmetry. Experiments were performed at 1.55 µm wavelength for potential telecommunication applications.
Acoustic wave exhibits inherently different characters when propagating in sonic band-gap materials. We address negative refractions of acoustic wave both experimentally and theoretically in two dimensional sonic crystals constructed with steel rods embedded in air. With lattice symmetry and artificial ldquoatomsrdquo designing, refraction of acoustic wave in the crystals could be manipulated from...
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