Multi-channel parallel ultrasound detection based on a photothermal tunable fiber optic sensor array

Abstract

A multi-channel parallel ultrasound detection system based on a photothermal tunable fiber optic sensor array is proposed. The resonant wavelength of the ultrasound sensor has a quadratic relationship with the power of a 980-nm heating laser. The maximum tuning range is larger than 15 nm. Through photothermal tuning, the inconsistent operating wavelengths of the Fabry–Perot (FP) sensor array can be solved, and then a multiplexing capacity of up to 53 can be theoretically realized, which could greatly reduce the time required for data acquisition. Then, a fixed wavelength laser with ultra-narrow linewidth is used to interrogate the sensor array. The interrogation system demonstrates a noise equivalent pressure (NEP) as low as 0.12 kPa, which is 5.5-times lower than the commercial hydrophone. Furthermore, a prototype of a four-channel ultrasound detection system is built to demonstrate the parallel detection capability. Compared with the independent detection, the SNR of parallel detection does not deteriorate, proving that the parallel detection system and the sensor array own very low cross talk characteristics. The parallel detection technique paves a way for real-time photoacoustic/ultrasound imaging.

Ultrasound sensing with optical microcavities

“…However, the F-P cavities in different channels may have different resonance wavelengths, which poses a challenge for optical readout. To address this issue, Yang et al demonstrated a photothermal tunable fiber optic ultrasound sensor array, where the resonant wavelength of each cavity can be controlled by a laser 69 . Furthermore, Ma et al proposed a 4 × 16 fiber-optic array based on F-P cavities, which enabled parallel sensing for imaging with a volume rate of 10 Hz 70 .…”

Miniaturized fiber optic ultrasound sensor with multiplexing for photoacoustic imaging

“…Among them, fiber optic resonant structures for ultrasound sensors have strong competivity [12] , [16] , [17] , [18] , due to the outstanding performances of high sensitivity and smaller size. In theory, the sensor structures including polymer-membrane based Fabry-Perot interferometers (FPI) [12] , [19] , fiber gratings [15] , [20] and micro-ring resonators [17] have extremely high sensitivity with a very small footprint owing to the long interaction length. The spectral sideband filter technique is commonly used to achieve signal demodulation for ultrasound detection [21] , [22] , [23] .…”