Moiré pattern

About: Moiré pattern is a research topic. Over the lifetime, 1917 publications have been published within this topic receiving 27176 citations. The topic is also known as: moiré fringes & moire pattern.

Moiré bands in twisted trilayer black phosphorene: effects of pressure and electric field.

Abstract: Twist-induced moiré bands and accompanied correlated phenomena have been extensively investigated in twisted hexagonal lattices with weak interlayer coupling. However, the formation of moiré bands in strongly coupled layered materials and their controlled tuning remain largely unexplored. Here, we systematically study the moiré bands in twisted trilayer black phosphorene (TTbP) and the influences of pressure and electric field on them. Moiré states can form in various TTbPs even when the twist angle is larger than 16° similar to that of twisted bilayer bP. However, different TTbPs show different localization patterns depending on the twisting layer, leading to distinct dipolar behaviors. While these moiré states become quasi-one-dimensional (1D) as the twist angle decreases, external pressure causes the crossover of moiré states from quasi-1D to 0D with a dramatic change in localization areas and greatly reduced bandwidth. Interestingly, compared to twisted bilayer and pristine bP, TTbPs show a much larger electric-field induced Stark effect, controllable by either the twist angle or twist layer. Our work thus demonstrates TTbP as an attractive platform to explore moiré-controlled electronic and optical properties, as well as tunable optoelectronic applications.

Direct Observation of a Localized Flat-Band State in a Mapped Moiré Hubbard Photonic Lattice

Abstract: When two identical periodic structures are stacked at a series of discrete rotation angles, the resulting moir\'e pattern brings an extreme flat band with transport enhancement. It provides insights into the fascinating physics of insulating states and unconventional superconductivity with delocalization-localization transitions and commensurable-incommensurable phases. However, the exploration of symmetry- and geometry-independent flat-band physics with moir\'e patterns is still rare, limited by the stringent requirement in high dimension. Here, we experimentally observe the localized flat-band state by mapping a moir\'e model into a one-dimensional photonic lattice using a femtosecond laser direct writing technique. By accurately controlling the external periodic field, we construct moir\'e photonic lattices with different moir\'e band structures. We successfully observe the photon-walker evolution from splitting with dispersion to nondispersive propagation with larger localization in the input ports as the result of a flat band induced by moir\'e patterns with larger period. Our approach to engineering moir\'e model, together with the integrated photonic implementation, establishes a powerful tool for exploring the effects accompanying the transition from commensurate to incommensurate phases.

Metal wire expansion coefficient measuring method

Abstract: The invention relates to a metal wire expansion coefficient measuring method which includes steps of engraving grating fringe on a to-be-measured metal surface by means of grating engraving, acquiring a digital image of objective grating, making a reference grating, acquiring a digital image of the expanded objective grating, superposing the digital image of the reference grating and the digital image of the objective grating to obtain a first moire fringe, superposing the digital image of the reference grating and the expanded objective grating to obtain a second moire fringe, refining the first moire fringe and the second moire fringe by Fourier transform, filter treatment and extremum method to obtain a first refined isochromatic fringe and a second refined isochromatic fringe which is generated from the second moire fringe correspondingly, calculating slope and inclination of the corresponding isochromatic fringe by the least square method to obtain the variable B of the inclination of the corresponding isochromatic fringe relative to an X-axis of the measuring system due to change of temperature, then calculating the calibrated slope k and calculating the dependent variable epsilon xx on the condition that the temperature is equal to T2, and finally calculating expansion coefficient a of materials.

Surface evaluation combining the moire effect and phase-stepping techniques in Fizeau interferometry

Abstract: The usual phase-stepping algorithms are employed to evaluate the phase of Fizeau interferograms in topographic measurements. The superposition of the interferogram with a Ronchi grid provides a Moire pattern. The phase modulation is obtained by the in plane displacement of the grid, while a sinusoidal intensity pattern is obtained by defocusing the image acquisition system. In this work, the measurement range of the method in the function of the maximum variation of height surfaces is calculated and verified.

Automated Talbot interferometer using Moire fringe scanning and ray tracing

Abstract: An automated Talbot interferometer using Moiré fringe scanning and ray tracing is proposed. Our novel method can obtain the wavefront aberration by a phase object on the plane where the object itself is situated.