Chao Chung-Yen, Ashkenazi Shai, Huang Sheng-Wen, O'Donnell Matthew, Guo L Jay
Department of Electrical Engineering and Computer Science at the University of Michigan, Ann Arbor, MI 48109, USA.
IEEE Trans Ultrason Ferroelectr Freq Control. 2007 May;54(5):957-65. doi: 10.1109/tuffc.2007.341.
Polymer microring resonators are demonstrated as high-frequency, ultrasound detectors. An optical microring resonator consists of a ring waveguide closely coupled to a straight bus waveguide, serving as light input and output. Acoustic waves irradiating the ring induce strain, deforming the waveguide dimensions and changing the refractive index of the waveguide via the elasto-optic effect. These effects modify the effective refractive index of the guided mode inside the waveguide. The sharp wavelength dependence of the microring resonance can enhance the optical response to acoustic strain. Such polymer microring resonators are experimentally demonstrated in detecting broadband ultrasound pulses from a 50 MHz transducer. Measured frequency response shows that these devices have potential in high-frequency, ultrasound detection. Design guidelines for polymer microring resonators forming an ultrasound detector array are discussed.
聚合物微环谐振器被证明可作为高频超声探测器。光学微环谐振器由一个与直的总线波导紧密耦合的环形波导组成，总线波导用于光的输入和输出。照射微环的声波会引起应变，使波导尺寸变形，并通过弹光效应改变波导的折射率。这些效应会改变波导内导模的有效折射率。微环谐振的尖锐波长依赖性可增强对声应变的光学响应。这种聚合物微环谐振器已通过实验证明可用于检测来自50 MHz换能器的宽带超声脉冲。测量的频率响应表明，这些器件在高频超声检测方面具有潜力。文中还讨论了构成超声探测器阵列的聚合物微环谐振器的设计准则。
