Wei Heming, Sun Kexuan, Wei Yan, Zhu Mengshi, Zhang Haiyan, Pang Fufei, Wang Tingyun, Krishnaswamy Sridhar
Opt Lett. 2023 Aug 15;48(16):4412-4415. doi: 10.1364/OL.500428.
We demonstrate a diaphragm-integrated ring waveguide coupler fabricated by the two-photon direct laser wring technique as an ultrasonic sensor, which is integrated on an optical fiber tip. The device consists of a micro-ring waveguide with a diameter of 5 µm functionalized as an optical fiber tip light reflection mirror and a straight waveguide connecting a diaphragm. The evanescent field coupling can be realized between the two waveguides, and the coupling efficiency can be changed due to the variation of the coupling gap induced by ultrasound. Accordingly, the light reflection can be changed. Based on the plate vibration theory, the vibration frequency can be changed through optimizing the diaphragm size. The experiments show that the device exhibits a high sensitivity and low noise equivalent acoustic signal level of 1.07 mPa/Hz at 100 kHz, which has great potential in various acoustic wave sensing applications.
我们展示了一种通过双光子直接激光写入技术制造的集成隔膜的环形波导耦合器，作为一种超声传感器，它集成在光纤尖端。该器件由一个直径为5 µm的微环波导（功能化为光纤尖端光反射镜）和一个连接隔膜的直波导组成。两个波导之间可实现倏逝场耦合，并且由于超声引起的耦合间隙变化，耦合效率会发生改变。相应地，光反射也会改变。基于平板振动理论，通过优化隔膜尺寸可以改变振动频率。实验表明，该器件具有高灵敏度，在100 kHz时噪声等效声信号水平低至1.07 mPa/Hz，在各种声波传感应用中具有巨大潜力。
