Opt Lett. 2020 Mar 1;45(5):1128-1131. doi: 10.1364/OL.383238.
An ultra-compact ultrasound sensor with a chalcogenide (ChG) microfiber and a silica microfiber is fabricated. It can detect the ultrasound wave generated by a piezoelectric transducer peaked at 3.7 MHz. The sensor shows the broadband ultrasound frequency response with a high signal-to-noise ratio (SNR), owing to the high refractive index and small Young's modulus of ChG material. A ChG (${{\rm As}_2}{{\rm Se}_3}$AsSe) microfiber of 2 µm diameter is adhered to the surface of a silica microfiber with a diameter of 5 µm via Van der Waals force; the transmission spectrum has high contrast due to multi-mode interference in this hybrid structure. The SNR response could be up to 70 dB, especially at low frequency due to the soft ChG microfiber as a sensing unit to magnify the ultrasound signal, along with an SNR over 12 dB at ultrasound of 31.2 MHz. As a comparison, a silica taper with the same size as the ChG microfiber is also placed on the silica microfiber with a diameter of 5 µm to detect an ultrasound signal from 18 kHz to 9.4 MHz with an SNR lower than that based on the ChG microfiber up to 38.8 dB, showing the high sensitivity of the ChG microfiber.
一种超紧凑的超声传感器，由硫属化物（ChG）微光纤和二氧化硅微光纤组成。它可以检测到压电换能器产生的峰值为 3.7MHz 的超声波。由于 ChG 材料具有高折射率和小杨氏模量，传感器具有宽带超声频率响应和高信噪比（SNR）。直径为 2µm 的 ChG（${{\rm As}_2}{{\rm Se}_3}$AsSe）微光纤通过范德华力粘附在直径为 5µm 的二氧化硅微光纤表面上；由于多模干涉，这种混合结构具有高对比度的传输光谱。由于作为传感单元的软 ChG 微光纤可以放大超声信号，因此 SNR 响应可高达 70dB，特别是在低频时，并且在 31.2MHz 的超声下 SNR 超过 12dB。相比之下，同样尺寸的二氧化硅锥形也放置在直径为 5µm 的二氧化硅微光纤上，以检测从 18kHz 到 9.4MHz 的超声信号，其 SNR 低于基于 ChG 微光纤的 SNR，最高可达 38.8dB，表明 ChG 微光纤具有高灵敏度。
