Low-noise wideband ultrasound detection using polymer microring resonators

Abstract

Polymer microring resonators for low-noise, wideband ultrasound detection are presented. Using a nanoimprinting technique, we fabricated polymer microring resonators with a quality factor of 6000 resulting in high sensitivity to ultrasound. A noise-equivalent pressure of 0.23 kPa over 1-75 MHz and a detection bandwidth of over 90 MHz at -3 dB were measured. These results demonstrate the potential of polymer microring resonators for high-frequency ultrasound and photoacoustic imaging. For a typical photoacoustic imaging test case, the high sensitivity demonstrated in these devices would increase imaging depth by a factor of 3 compared to state-of-the-art polyvinylidene fluoride detectors.

High-sensitivity and wide-directivity ultrasound detection using high Q polymer microring resonators

“…Optical detection of ultrasound [5][6][7][8][9]15 could potentially address the above issues. It can achieve a low NEP ͑Ӷ1 kPa͒ with relative small element size and wideband response, 8 and would be easier to create dense arrays with small element size.…”

“…It can achieve a low NEP ͑Ӷ1 kPa͒ with relative small element size and wideband response, 8 and would be easier to create dense arrays with small element size. 17 We have been exploiting polymer microring resonators as ultrasound detectors, and have demonstrated a low NEP of ϳ230 Pa over a wide bandwidth of 1-75MHz even with a relatively low cavity Q factor of 6000 in the past.…”

“…8 Besides, a flat frequency response from dc to over 90 MHz at Ϫ3 dB was calibrated by a wideband photoacoustic source. 8 With improved fabrication, further reduction in device's NEP ͑ϳ88 Pa͒ has been realized using a higher Q factor microring device.9 However the device diameter ͑D͒ was still around 100 m, limiting the high-resolution imaging applications. Smaller microrings were shown to suffer from higher surface scattering loss, leading to a lower Q factor and decreased sensitivity.…”

“…17 We have been exploiting polymer microring resonators as ultrasound detectors, and have demonstrated a low NEP of ϳ230 Pa over a wide bandwidth of 1-75MHz even with a relatively low cavity Q factor of 6000 in the past. 8 Besides, a flat frequency response from dc to over 90 MHz at Ϫ3 dB was calibrated by a wideband photoacoustic source. 8 With improved fabrication, further reduction in device's NEP ͑ϳ88 Pa͒ has been realized using a higher Q factor microring device.…”

All-optically integrated photoacoustic and optical coherence tomography: A review

“…38 Chen et al used polymer micro-ring resonator as a PA signal detection system, the detection bandwidth up to 90 MHz, to achieve highresolution imaging of biological tissue. [39][40][41] In order to achieve the noncontact detection of ultrasonic signals, Wang Yi et al employed the low coherence Michelson interferometer (the detection bandwidth up to 17 MHz) achieving noncontact PA signal detection. 28 In 2012, Cedric Blatter adopted phasesensitive optical coherence tomography system to realize the noncontact measurements of PA signals (the bandwidth of 13 MHz), and acquired PA and OCT images of simulated samples.…”