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Highly sensitive vector curvature sensor based on two juxtaposed fiber Michelson interferometers with Vernier-like effect
摘要： In this paper, a highly sensitive vector curvature sensor based on two juxtaposed fiber Michelson interferometers (MI) with Vernier-like effect has been proposed and verified. Different from the structures of the conventional Vernier effect which are composed of the cascaded elements, the proposed configuration consists of two juxtaposed MIs. A triple-core fiber (TCF) is connected with a quite short piece of dual-side-hole fiber (DSHF), and the core of the DSHF and the two eccentric cores of the TCF are respectively constituted two juxtaposed MIs. Vernier-like effect is caused by the very small refractive index difference between the two eccentric cores of the TCF. The most outstanding feature of the proposed structure is that the two MIs are both sensitive to curvature with opposite sensitivities, which makes the curvature sensitivity magnification factor twice that of the conventional Vernier effect structure. Experimental results show that the curvature sensitivity of the structure can reach -60.84 nm/m-1.
关键词： triple-core fiber,curvature sensor,interferometer
更新于2025-09-04 15:30:14
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The effects of curvature on the thermal conduction of bent silicon nanowire
摘要： Curvature induced by mechanical deformation in nanostructures has been found to significantly affect their stability and reliability during applications. In this work, we investigated the effects of curvature induced by mechanical bending on the thermal properties of silicon nanowire (SiNW) by using molecular dynamics simulations. By examining the relationship between the curved geometry and local temperature/heat flux distribution, we found that there is no temperature gradient/heat flux along the radial direction of the bent SiNW, and the local heat current density along the circumferential direction varies with the radius of curvature. Interestingly, a ～10% reduction in the thermal conductivity is found in the bent SiNW due to the depression of long-wavelength phonons caused by its inhomogeneous deformation. The present work demonstrates that the curvature induced by mechanical bending can be used to modulate the thermal conductivity of SiNWs.
关键词： thermal conductivity,curvature,silicon nanowire,thermal conduction,molecular dynamics simulations
更新于2025-09-04 15:30:14
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Topologically Nontrivial Valley States in Bilayer Graphene Quantum Point Contacts
摘要： We present measurements of quantized conductance in electrostatically induced quantum point contacts in bilayer graphene. The application of a perpendicular magnetic field leads to an intricate pattern of lifted and restored degeneracies with increasing field: at zero magnetic field the degeneracy of quantized one-dimensional subbands is four, because of a twofold spin and a twofold valley degeneracy. By switching on the magnetic field, the valley degeneracy is lifted. Because of the Berry curvature, states from different valleys split linearly in magnetic field. In the quantum Hall regime fourfold degenerate conductance plateaus reemerge. During the adiabatic transition to the quantum Hall regime, levels from one valley shift by two in quantum number with respect to the other valley, forming an interweaving pattern that can be reproduced by numerical calculations.
关键词： quantum point contacts,quantized conductance,valley degeneracy,bilayer graphene,Berry curvature
更新于2025-09-04 15:30:14