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Opto-mechanics driven fast martensitic transition in two-dimensional materials
摘要： Diffusional phase-change materials, such as Ge-Sb-Te alloys, are used in rewritable non-volatile memory devices. But the continuous pursuit of readout/write speed and reduced energy consumption in miniaturized devices calls for optically driven, diffusionless phase change scheme in ultra-thin materials. Inspired by optical tweezers, in this work, we illustrate theoretically and computationally that a linearly polarized laser pulse with selected frequency can drive an ultrafast diffusionless martensitic phase transition of two-dimensional ferroelastic materials such as SnO and SnSe monolayers, where the unit-cell strain is tweezed as a generalized coordinate that affects the anisotropic dielectric function and electromagnetic energy density. At laser power of 2.0×1010 and 7.7×109 W/cm2, the transition potential energy barrier vanishes between two 90°-orientation variants of ferroelastic SnO and SnSe monolayer, respectively, so displacive domain switching can occur within picoseconds. The estimated adiabatic thermal limit of energy input in such optomechanical martensitic transition (OMT) is at least two orders of magnitude lower than that in Ge-Sb-Te alloy.
关键词： martensitic phase transition,ferroelasticity/ferroelectricity,two-dimensional materials,dielectric function,density functional theory,opto-mechanics
更新于2025-09-23 15:21:01
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Opto-Mechanical Interactions in Multi-Core Optical Fibers and their Applications
摘要： Optical fibers containing multiple cores are being developed towards capacity enhancement in space-division multiplexed optical communication networks. In many cases, the fibers are designed for negligible direct coupling of optical power among the cores. The cores remain, however, embedded in a single, mechanically-unified cladding. Elastic (or acoustic) modes supported by the fiber cladding geometry are in overlap with multiple cores. Acoustic waves may be stimulated by light in any core through electrostriction. Once excited, the acoustic waves may induce photo-elastic perturbations to optical waves in other cores as well. Such opto-mechanical coupling gives rise to inter-core cross-phase modulation effects, even when direct optical crosstalk is very weak. The cross-phase modulation spectrum reaches hundreds of megahertz frequencies. It may consist of discrete and narrow peaks, or may become quasi-continuous, depending on the geometric layout. The magnitude of the effect at the resonance frequencies is comparable with that of intra-core cross-phase modulation due to Kerr nonlinearity. Two potential applications are demonstrated: single-frequency opto-electronic oscillators that do not require radio-frequency electrical filters, and point-sensing of liquids outside the cladding of multi-core fibers, where light cannot reach.
关键词： opto-electronic oscillators,multi-core fibers,stimulated Brillouin scattering,optical fiber sensors,Opto-mechanics,nonlinear fiber-optics
更新于2025-09-16 10:30:52