The capability to modulate the intensity of an optical beam has scientific and practical significance. In this work, we demonstrate Y-Z cut lithium niobate acousto-optic modulators with record-high modulation efficiency, requiring only $1.5~\text{W}/\text{cm}^2$ for 100% modulation at 7 MHz. These modulators use a simple fabrication process; coating the top and bottom surfaces of a thin lithium niobate wafer with transparent electrodes. The fundamental shear acoustic mode of the wafer is excited through the transparent electrodes by applying voltage with frequency corresponding to the resonant frequency of this mode, confining an acoustic standing wave to the electrode region. Polarization of light propagating through this region is modulated at the applied frequency. Polarization modulation is converted to intensity modulation by placing the modulator between polarizers. To showcase an important application space for this modulator, we integrate it with a standard image sensor and demonstrate 4 megapixel time-of-flight imaging
高效的片上声光调制器作为微波-光转换的关键器件，在微波-光转换中占有特殊的地位。优选采用均匀的薄膜锂酸盐来构建形成声学谐振腔的悬浮配置，以提高装置的调制效率。然而，有限的腔长和复杂的制作工艺限制了调制效率的进一步突破，并对波导制造提出了挑战。在这项工作中，基于非悬浮薄膜锂硅酸盐-硫系玻璃混合马赫-曾德尔干涉仪波导平台，我们提出并演示了一种内置推挽式声光调制器，其半波电压长度积低至0.03 V cm，调制效率可与最先进的悬浮对应物相媲美。基于低功耗的优点，利用我们研制的内置推挽式声光调制器实现了微波调制链路。该声光调制器的优异性能得益于硫属化物薄膜优异的光弹性能和阻抗匹配叉指换能器激发的反对称瑞利声表面波模式的完全双向参与，克服了传统推挽式声光调制器中马赫-曾德尔干涉仪两臂上声表面波振幅差的问题。
Uncooled low-noise thin-film optomechanical resonator for thermal sensing on lithium niobate
University of California, Berkeley（加州大学伯克利分校）；Ming Hsieh Department of Electrical and Computer Engineering, University of Southern California（南加州大学明希电子与计算机工程学院）；Lawrence Berkeley National Laboratory（劳伦斯伯克利国家实验室）；Chandra Family Department of Electrical and Computer Engineering, The University of Texas at Austin（德克萨斯大学奥斯汀分校昌德拉家庭电子与计算机工程学院）
High-Efficiency Acousto-Optic Modulation on Non-Suspended Thin-Film Lithium Tantalate
University of Science and Technology of China（中国科学技术大学）；Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences（中国科学院上海微系统信息技术研究所）；University of Chinese Academy of Sciences（中国科学院大学）
