论文标题
GHz频率处的局部共鸣纳米条语音跨表面的非线性效应
Nonlinear effects in locally-resonant nanostrip phononic metasurface at GHz frequencies
论文作者
论文摘要
在本文中，我们报告了在纳米带语音跨表面（NPM）中观察到非线性效应的观察，该纳米带语音元素效应能够调整1.42 GHz的共振频率。由周期性纳米带阵列制成的NPM谐振器在尼橙酸锂底物上制造。每个纳米条的宽度为250 nm，由680 nm厚的SIO2层堆叠在50 nm Al金属电极上。有限元分析表明，该设备以垂直极化的（压缩）模式运行，纳米丝带中有大量的声能，从而导致低声速下的局部共振。由于非线性，随着刺激功率从10到30 dBm的增加，设备的共振频率逐次降低。发现非线性的基本机制是相邻纳米弹簧的功率依赖性耦合。这种耦合诱导底物表面区域的软化，从而降低了声速，从而降低了散装辐射。结果，发现NPM谐振器的质量因素随着刺激功率的增加而改善。 NPM谐振器中纳米带的功率依赖性耦合证明了一种可靠的方法来实现语音跨面中非线性的方法，这将显着丰富在高频下操纵表面声波的机制。
In this paper, we report on the observation of nonlinear effects in a nanostrip phononic metasurface (NPM) that enable the tuning of resonance frequencies at 1.42 GHz. The NPM resonator made of periodic nanostrip array is fabricated on a lithium niobate substrate. Each of the nanostrip is 250-nm wide and is made of 680-nm-thick SiO2 layer stacking on 50-nm Al metal electrodes. Finite element analysis reveals that the device operates in a vertically polarized (compression) mode with substantial acoustic energy confined in the nanostrips, leading to a local resonance at low acoustic velocity. Due to the nonlinearity, the resonance frequency of the device decreases quadratically with the increase of stimulation power from 10 to 30 dBm. The underlying mechanism of the nonlinearity is found to be the power-dependent coupling of the adjacent nanostrips. This coupling induces softening of the substrate surface region, which reduces the acoustic velocity and hence the bulk radiation. As a result, the quality factor of the NPM resonator is found to improve with the increase of stimulation power. The power-dependent coupling of nanostrips in the NPM resonator demonstrates a reliable method for the realization of nonlinearity in phononic metasurfaces, which would significantly enrich the mechanisms for the manipulation of surface acoustic waves at high frequencies.
