Whispering gallery mode (WGM) microcavities have been widely used for high-sensitivity ultrasound detection, owing to their optical and mechanical dual-resonance enhanced sensitivity. The ultrasound sensitivity of the cavity optomechanical system is fundamentally limited by thermal noise. In this work, we theoretically and experimentally investigate the thermal-noise-limited sensitivity of a WGM microdisk ultrasound sensor and optimize the sensitivity by varying the radius and a thickness of the microdisk, as well as using a trench structure around the disk. Utilizing a microdisk with a radius of 300 μm and thickness of 2 μm, we achieve a peak sensitivity of at 82.6 kHz. To the best of our knowledge, this represents the record sensitivity among cavity optomechanical ultrasound sensors. Such high sensitivity has the potential to improve the detection range of air-coupled ultrasound sensing technology.
2023, 11(7): 1139
Magnetostrictive optomechanical cavities provide a new optical readout approach to room-temperature magnetometry. Here we report ultrasensitive and ultrahigh bandwidth cavity optomechanical magnetometers constructed by embedding a grain of the magnetostrictive material Terfenol-D within a high quality () optical microcavity on a silicon chip. By engineering their physical structure, we achieve a peak sensitivity of comparable to the best cryogenic microscale magnetometers, along with a 3 dB bandwidth as high as 11.3 MHz. Two classes of magnetic response are observed, which we postulate arise from the crystallinity of the Terfenol-D. This allows single crystalline and polycrystalline grains to be distinguished at the level of a single particle. Our results may enable applications such as lab-on-chip nuclear magnetic spectroscopy and magnetic navigation.
2020, 8(7): 07001064
Due to their high quality factors and small mode volumes, whispering gallery mode (WGM) microcavities can strongly enhance light-matter interactions, making them an excellent platform for various sensing applications. In this paper we review the burgeoning field of microcavity sensing. We first present recent state-of-the-art results, and discuss microcavity sensing platforms and mechanisms. We then review a variety of WGM sensing applications, including the sensing of single nanoparticles, temperatures, magnetic fields, chemical gases, and strain/stress. Furthermore, we provide a brief summary and outlook on microcavity-based sensing devices and their potential applications.回音壁模式光学微腔 微腔传感 单纳米颗粒检测 生物传感 磁场传感 whispering-gallery microcavity microcavity sensing single nanoparticle detection biosensing magnetometry
Journal of Semiconductors
景象匹配对匹配算法的运行速度和内存占用均要求较高。为提升归一化互相关算法的运行速度并降低其内存占用率，本文重点对其中的基准子图能量计算步骤进行了加速研究。经过详细分析，积分图法具有灵活、快速的优点，但缺陷为其在快速计算的同时需花费较大内存，并不适合直接应用在嵌入式系统中。本文提出了一种快速递推算法。该算法利用相邻像素值的能量进行连续递推，计算时可以不必像积分图法那样给所有的图像能量都分配空间，只需预留1行的像素空间便能完成整个能量计算过程。实验结果表明: 在时间花费方面，快速递推法具有和积分图法相当的运算速度，耗时均只为传统归一化互相关算法的1/2; 在内存占用率方面，快速递推法约为积分图法的1/3以下，且实时图尺寸越大，快速递推法占用的内存越小。综上所述，在归一化互相关算法中利用经典积分图法和本文提出的快速递推法计算基准子图能量，均较传统NCC算法有所加速，两种算法各具优点，经典积分图法快速、灵活，适用于对速度要求高，但对内存占用率要求不太高的应用场景; 而快速递推法快速、省内存，更适用于嵌入式系统的应用。归一化互相关 基准子图能量 经典积分图法 快速递推法 Normalize Cross Correlation(NCC) sub-image’s energy classic integral image method fast Recurrence method
2018, 26(10): 2565
The effect of temperature on the dynamics of a laser-induced cavitation bubble is studied experimentally. The growth and collapse of the cavitation bubble are measured by two sensitive fiber-optic sensors based on optical beam deflection (OBD). Cavitation bubble tests are performed in water at different temperatures, and the temperature ranges from freezing point (0 °C) to near boiling point. The results indicate that both the maximum bubble radius and bubble lifetime are increased with the increase of temperature. During the stage of bubble rapidly collapsing in the vicinity of a solid surface, besides laser ablation effect, both the first and second liquid-jet-induced impulses are also observed. They are both increased with liquid temperature increasing, and then reach a peak, followed by a decrease. The peak appears at the temperature which is approximately the average of freezing and boiling points. The mechanism of liquid temperature influence on cavitation erosion is also discussed.
2013, 9(4): 317
为了研究环境压强对固壁面附近激光空泡溃灭射流的影响, 采用光偏转方法对固体壁面附近空泡溃灭行为进行了实验研究, 得到了不同环境压强下空泡的溃灭时间、溃灭射流冲击压强。结果表明, 相同激光能量下, 环境压强对空泡溃灭时间、射流冲击压强都有非线性的影响关系, 环境压强越大, 溃灭时间越小, 射流冲击压强越大; 在空泡溃灭的前期, 泡壁加速率较小且受环境压强的影响较小; 在溃灭的后期, 射流形成, 空泡上表面泡壁中心点速率迅速增大, 且相应阶段的加速率随着环境压强的增大而增大。这一结果对激光水下加工及空泡动力学的研究有积极的意义。激光物理 激光空泡 光偏转法 液体射流 水锤 laser physics laser-induced bubble optical beam deflection liquid jet water hammer