Opt Lett. 2023 Feb 15;48(4):868-871. doi: 10.1364/OL.479718.
All-optical ultrasound probes with fully integrated ultrasound generation and detection functions demonstrate some unique advantages over traditional electroacoustic counterparts. However, due to the lack of an effective solution, the most commonly used method is to assemble two separate functional optical fibers together for ultrasound generation and detection, respectively. In this Letter, an innovative strategy, to the best of our knowledge, is developed to integrate the photoacoustic effect based ultrasound generation and the Fabry-Pérot (FP) interference based ultrasound detection structures together at the end of a single double clad optical fiber (DCF), so as to make a compact forward-viewing ultrasound self-transceiving probe (1-mm diameter). From the experiment results, the as-fabricated probe can generate an ultrasound signal with an amplitude of 2.36 MPa at 2.25 mm in the transmitting mode, and its peak frequency and -6-dB bandwidth are measured to be 10.64 MHz and 22.93 MHz, respectively. When being operated under the receiving mode, the probe has a detection sensitivity of 208.4 mV/MPa for ultrasound signals with the peak frequency of 8.24 MHz, and the noise equivalent pressure (NEP) is 76.8 kPa. In addition, the forward-viewing format ultrasound self-transceiving experiment is also performed and the pulse-echo signal varying with the transmission distance is successfully captured for the first time.
全光学超声探头具有完全集成的超声产生和检测功能，相对于传统的电声换能器具有一些独特的优势。然而，由于缺乏有效的解决方案，最常用的方法是分别将两个单独的功能光纤组装在一起，分别用于超声产生和检测。在本信中，提出了一种创新策略，据我们所知，将基于光声效应的超声产生和基于法布里-珀罗（FP）干涉的超声检测结构集成在一起，位于单根双包层光纤（DCF）的末端，从而制造出一种紧凑的前向观察超声自收发探头（直径 1 毫米）。从实验结果来看，所制造的探头在发射模式下可以在 2.25 毫米处产生幅度为 2.36 MPa 的超声信号，其峰值频率和-6dB 带宽分别测量为 10.64 MHz 和 22.93 MHz。当在接收模式下工作时，该探头对峰值频率为 8.24 MHz 的超声信号具有 208.4 mV/MPa 的检测灵敏度，噪声等效压力（NEP）为 76.8 kPa。此外，还进行了前向观察格式的超声自收发实验，首次成功捕获了随传输距离变化的脉冲回波信号。
