Suppression of reverberations at fiber tips for optical ultrasound sensing

Abstract

Fabry–Perot-based ultrasound sensors at fiber tips have performed high sensitivity and immunity of electromagnetic interference with a relatively compact size. Nevertheless, the reverberation at fiber tips causes a strong noise that degrades the sensing capability. Here we propose a fiber optical-based ultrasound sensor with three design approaches to reduce the reverberation, including designs with an eccentric core, absorptive shield, and arc edge. The effect was experimentally validated with a photoacoustic signal excitation. Compared with bare single-mode fibers in simulation, the low-reverberation design increased the signal-to-noise ratio by 32.1 dB with identical excitation. The experimental results demonstrated the “clean” response with almost invisible reverberations, which was validated by a commercial hydrophone. This research solved the reverberation problems and provided a low-noise design for fiber optic ultrasound sensing.

Advances in Multicore Fiber Interferometric Sensors

“…The reported four different structures of MCF interferometric sensors exhibit their own advantages and disadvantages. For example, MCF-based FPIs are able to achieve a very tiny size of the sensor head (less than 200 μm [ 13 , 14 , 24 , 31 , 32 , 34 ]), and each core can be used to fabricate an individual sensor, which can measure differential responses in distinct cores separately [ 13 , 14 , 24 , 31 , 32 , 33 ]. However, the manipulation of an individual core in the MCF is still a technical challenge, thus it is difficult to fabricate intrinsic FPIs in different cores of MCF.…”

“…Furthermore, the high bending sensitivity of FPIs can also be used for vibration sensing. For example, in 2020, Xiandong Ma et al proposed a broadband ultrasound sensor [ 34 ], where the eccentric cores of MCFs were used to fabricate FPIs, and the reverberating noise was decreased from −1 dB to −28 dB.…”

Optical ultrasound sensors for photoacoustic imaging: a narrative review

“…In 2017, an ultrasensitive FP sensor with a 340-μm-thick film created the minimum NEP to 2.6 Pa over a 2.8-MHz bandwidth (46). In order to solve the same problem, Ma et al (68) proposed three unique fiber optical-based designs with an eccentric core, an absorptive shield, and an arc edge. These approaches were applied to eliminate the constructive interference, optimize the energy dissipation, and reduce the noise level.…”

Proposal for a photoacoustic ultrasonic generator based on Tamm plasmon structures

“…In photoacoustic transducers, the absorber is heated and cooled, leading to mechanical deformations, which cause cycles of pressure, or, in the other words, acoustic waves in ambient surrounding [9]. The operation principle provides the number of advantages: reliability, compactness, full galvanic isolation [10], wideband operation [11], and possibility of realization of transducer at the edge of the optical fiber [12], that, in turn, leads to the immunity to harsh environment and electromagnetic interference. At the same time, further miniaturization, predefined spectrum of ultrasound as well as the increase of functional flexibility of the ultrasound generation is required.…”