A high-speed optical switch based on transforming the shape of nanomaterial through an interacting magnetic and thermal field

一种基于通过相互作用的磁场和热场改变纳米材料形状的高速光开关。摘要：磁场已经引起了一代又一代科学家和工程师的兴趣。其中一个原因是，一旦产生磁场，它就可以对电荷和电流提供几乎无限的力，比如洛伦兹力。如果这一点能够被利用，那么人们就可以拥有光、电子和数据存储技术，这些技术可以以非常低的功耗和低能耗运行。不幸的是，典型的磁铁，如冰箱磁铁，不能改变材料的光学特性，因为它对我们熟悉的环境中固体和液体内部流动的电荷施加的力非常弱。这就是自然界中没有磁场控制光学特性的材料的例子的原因之一。在这里，研究人员提出利用这样一个事实来解决这个问题：当材料融化或冻结时，在固体和液体区域之间的边界可以产生短暂的（几纳秒）但非常大的电流。这种瞬态电流可能足够大，以至于当冰箱磁铁靠近它时，材料会发生很大的变形。因此，物理性质，如光的传输可以显著改变。他们将这种效应称为磁热效应或数学效应，并期望创造一种基于可逆改变其光透明度的新型高速光开关设备。这种装置可以在光学和量子计算硬件以及电子元件中得到应用。通过纳秒脉冲激光加热，可以在纳米材料内部产生包含凝固或熔化前沿的大瞬态热梯度。初步假设认为，在移动相锋的边界，即凝固或熔化锋，质量密度差造成电荷不平衡，导致瞬态电流密度大。热模拟研究和实验表明，在中等强度的磁场作用下，被纳秒脉冲熔化的10 ~ 100 nm尺寸的金属纳米颗粒会发生形状变形甚至破裂。由于这些形状变化和破裂效应可以通过激光热脱湿效应逆转，因此在同时存在磁场和热场的情况下，光学性质可以实现非常快速的变化。本研究的目标是设计、制造和演示一种基于金属纳米颗粒的磁场分解和热场重组的光学器件。研究人员计划结合薄膜沉积、低成本的纳米球光刻、蚀刻、脉冲激光熔化和光学表征。他们将研究器件性能作为激光和材料参数的函数。他们预计所提出的任务也将增强他们对耦合磁热效应的基本理解。因此，新知识和新技术有望从计划的实验和理论研究。

A high-speed optical switch based on transforming the shape of nanomaterial through an interacting magnetic and thermal field. AbstractThe magnetic field has intrigued many generations of scientists and engineers. One reason is that, once a magnetic field is created it can supply an almost limitless force, such as the Lorentz force, on electrical charges and currents. If this could be exploited then one could have optical, electronic, and data storage technologies that operate on very low power with low energy consumption. Unfortunately, typical magnets, such as a refrigerator magnet, cannot change the optical properties of materials because it applies very weak forces on the charges flowing within the solids and liquids in our familiar environment. This is one reason why nature does not have examples of materials whose optical properties are controllable by magnetic fields. Here the researchers propose to solve this problem by utilizing the fact that when a material melts or freezes, a short lived (few nanoseconds) but extremely large current can be generated at the boundary between the solid and liquid regions. This transient current could be large enough such that, when a refrigerator magnet is brought in its vicinity, the material can be deformed substantially. Thus, physical properties such as the transmission of light can be dramatically changed. They call this effect the MAgneto-THermal or MaTh effect and anticipate the creation of a new type of high-speed optical switching device based on reversibly changing its light transparency. Such devices could find application in optical and quantum computing hardware and in electronic components. Large transient thermal gradients involving a solidification or melting front can be created within nanomaterials by heating by nanosecond pulsed laser light. Preliminary hypothesis suggests that at the boundary of a moving phase front, i.e. solidification or melting front, the mass density difference creates a charge imbalance resulting in a large transient current density. Thermal modeling studies and experiments show that metal nanoparticles in the 10-100 nm size range melted by nanosecond pulses can undergo shape deformation and even break-up in the presence of moderate magnetic fields. Since these shape changes and break-up effects can be reversed by laser thermal dewetting effects, a very fast change in optical properties can be achieved in the presence of a simultaneous magnetic and thermal field. The goal of the research is to design, fabricate, and demonstrate an optical device based on the magnetic field break-up and thermal field re-assembly of metal nanoparticles. The researchers plan to use a combination of thin film deposition, cost-effective nanosphere lithography, etching, pulsed laser melting, and optical characterization. They will investigate the device performance as a function of laser and materials parameters. They anticipate that the proposed tasks will also enhance their fundamental understanding of the coupled magnetic-thermal effect. Therefore, new knowledge as well as a new technology is expected from the planned experimental and theoretical investigations.