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Cao X, Yang H, Wu ZL, Li BB. Ultrasound sensing with optical microcavities. LIGHT, SCIENCE & APPLICATIONS 2024; 13:159. [PMID: 38982066 PMCID: PMC11233744 DOI: 10.1038/s41377-024-01480-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 04/10/2024] [Accepted: 05/13/2024] [Indexed: 07/11/2024]
Abstract
Ultrasound sensors play an important role in biomedical imaging, industrial nondestructive inspection, etc. Traditional ultrasound sensors that use piezoelectric transducers face limitations in sensitivity and spatial resolution when miniaturized, with typical sizes at the millimeter to centimeter scale. To overcome these challenges, optical ultrasound sensors have emerged as a promising alternative, offering both high sensitivity and spatial resolution. In particular, ultrasound sensors utilizing high-quality factor (Q) optical microcavities have achieved unprecedented performance in terms of sensitivity and bandwidth, while also enabling mass production on silicon chips. In this review, we focus on recent advances in ultrasound sensing applications using three types of optical microcavities: Fabry-Perot cavities, π-phase-shifted Bragg gratings, and whispering gallery mode microcavities. We provide an overview of the ultrasound sensing mechanisms employed by these microcavities and discuss the key parameters for optimizing ultrasound sensors. Furthermore, we survey recent advances in ultrasound sensing using these microcavity-based approaches, highlighting their applications in diverse detection scenarios, such as photoacoustic imaging, ranging, and particle detection. The goal of this review is to provide a comprehensive understanding of the latest advances in ultrasound sensing with optical microcavities and their potential for future development in high-performance ultrasound imaging and sensing technologies.
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Affiliation(s)
- Xuening Cao
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Hao Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Zu-Lei Wu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China
- School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan, 430074, China
| | - Bei-Bei Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing, 100190, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
- Songshan Lake Materials Laboratory, Dongguan, 523808, Guangdong, China.
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Irfan S, Kim JY, Kurt H. Ultra-compact and efficient photonic waveguide bends with different configurations designed by topology optimization. Sci Rep 2024; 14:6453. [PMID: 38499556 PMCID: PMC10948862 DOI: 10.1038/s41598-024-53881-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2023] [Accepted: 02/06/2024] [Indexed: 03/20/2024] Open
Abstract
Transporting light signals over the corners and sharp bends imposes high optical loss and distortion on the mode profiles. Usually, bends with larger radii are used in circuits to minimize the loss over transmission, resulting in a severe limitation in integration density. In this paper, we propose novel topology-optimized optimized L-bend and U-bend structures designed for a 220 nm silicon-on-insulator (SOI) platform. Optimized L-bends with footprints of 2.5 µm × 2.5 µm, 1.5 µm × 1.5 µm, and 1 µm × 1 µm show maximum insertion losses of only 0.07 dB, 0.26 dB, and 0.78 dB, respectively. For optimized U-bends with footprints of 3 µm × 3.6 µm, 2.5 µm × 2.5 µm, and 1.5 µm × 1.5 µm, the maximum insertion losses are 0.07 dB, 0.21 dB, and 3.16 dB. These optimized bends reduce the maximum insertion loss by over 50% compared to un-optimized arc-type bends across a broad wavelength range of 1450-1650 nm. Experimental verification of a meander line with 16 optimized U-bends (3 µm × 3.6 µm) demonstrates an averaged insertion loss of 1.23 dB in the wavelength range of 1520-1580 nm, agreeing with simulated results and indicating a high potential of loss reduction with optimized bends.
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Affiliation(s)
- Sabaina Irfan
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea
| | - Jae-Yong Kim
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea
| | - Hamza Kurt
- School of Electrical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, South Korea.
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Wang R, Liu W, Pan Z, Fan W, Liu L, Xing E, Zhou Y, Tang J, Liu J. High resolution acoustic sensing based on microcavity optomechanical oscillator. OPTICS EXPRESS 2024; 32:4816-4826. [PMID: 38439224 DOI: 10.1364/oe.510033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Accepted: 01/14/2024] [Indexed: 03/06/2024]
Abstract
In this paper, a simple sensing method based on a silicon oxide microcavity optomechanical oscillator (OMO) is proposed and demonstrated for the detection of acoustic signals. Firstly, the resonance damping was reduced by improving the optical quality factor (Qo) and increasing the sphere-to-neck ratio. After optimizing the process, a microsphere OMO was fabricated, which has an ultra-high mechanical quality factor (6.8 × 106) and greater sphere-to-neck ratio (∼11:1), based on which ultra-narrow linewidth phonon laser (∼1 Hz) is constructed. Secondly, by changing the refractive index of the coupling interval, the low-frequency acoustic pressure signal is efficiently coupled into the microcavity OMO to construct a high-resolution acoustic sensor. This sensing mechanism can not only measure the acoustic pressure, but also use the sideband signal in the modulation mechanism to measure the frequency of acoustic signals (15 Hz∼16 kHz), the sensitivity is 10.3 kHz/Pa, the minimum detectable pressure is 1.1 mPa, and noise-limited minimum detectable pressure is 28.8 µPa/Hz1/2. It is the highest detection resolution compared with the same type of low-frequency acoustic signal detection currently reported. This OMO-based acoustic sensing detection method opens up a new path for future miniaturized, ultra-high-precision, and cost-effective acoustic sensing.
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Nagli M, Moisseev R, Suleymanov N, Kaminski E, Hazan Y, Gelbert G, Goykhman I, Rosenthal A. Silicon photonic acoustic detector (SPADE) using a silicon nitride microring resonator. PHOTOACOUSTICS 2023; 32:100527. [PMID: 37645254 PMCID: PMC10461202 DOI: 10.1016/j.pacs.2023.100527] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/14/2023] [Accepted: 06/30/2023] [Indexed: 08/31/2023]
Abstract
Silicon photonics is an emerging platform for acoustic sensing, offering exceptional miniaturization and sensitivity. While efforts have focused on silicon-based resonators, silicon nitride resonators can potentially achieve higher Q-factors, further enhancing sensitivity. In this work, a 30 µm silicon nitride microring resonator was fabricated and coated with an elastomer to optimize acoustic sensitivity and signal fidelity. The resonator was characterized acoustically, and its capability for optoacoustic tomography was demonstrated. An acoustic bandwidth of 120 MHz and a noise-equivalent pressure of ∼ 7 mPa/Hz1/2 were demonstrated. The spatially dependent impulse response agreed with theoretical predictions, and spurious acoustic signals, such as reverberations and surface acoustic waves, had a marginal impact. High image fidelity optoacoustic tomography of a 20 µm knot was achieved, confirming the detector's imaging capabilities. The results show that silicon nitride offers low signal distortion and high-resolution optoacoustic imaging, proving its versatility for acoustic imaging applications.
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Affiliation(s)
- Michael Nagli
- Andrew and Erna Viterbi Faculty of Electrical Engineering, Technion – Israel Institute of Technology, Technion City 32000, Haifa, Israel
| | - Ron Moisseev
- Andrew and Erna Viterbi Faculty of Electrical Engineering, Technion – Israel Institute of Technology, Technion City 32000, Haifa, Israel
| | - Nathan Suleymanov
- Andrew and Erna Viterbi Faculty of Electrical Engineering, Technion – Israel Institute of Technology, Technion City 32000, Haifa, Israel
| | - Eitan Kaminski
- Andrew and Erna Viterbi Faculty of Electrical Engineering, Technion – Israel Institute of Technology, Technion City 32000, Haifa, Israel
| | - Yoav Hazan
- Andrew and Erna Viterbi Faculty of Electrical Engineering, Technion – Israel Institute of Technology, Technion City 32000, Haifa, Israel
| | - Gil Gelbert
- Andrew and Erna Viterbi Faculty of Electrical Engineering, Technion – Israel Institute of Technology, Technion City 32000, Haifa, Israel
| | - Ilya Goykhman
- Andrew and Erna Viterbi Faculty of Electrical Engineering, Technion – Israel Institute of Technology, Technion City 32000, Haifa, Israel
| | - Amir Rosenthal
- Andrew and Erna Viterbi Faculty of Electrical Engineering, Technion – Israel Institute of Technology, Technion City 32000, Haifa, Israel
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Volodarsky O, Hazan Y, Nagli M, Rosenthal A. Burst-mode pulse interferometry for enabling low-noise multi-channel optical detection of ultrasound. OPTICS EXPRESS 2022; 30:8959-8973. [PMID: 35299336 DOI: 10.1364/oe.449630] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 01/10/2022] [Indexed: 06/14/2023]
Abstract
Ultrasound detection via optical resonators can achieve high levels of miniaturization and sensitivity as compared to piezoelectric detectors, but its scale-up from a single detector to an array is highly challenging. While the use of wideband sources may enable parallel interrogation of multiple resonators, it comes at the cost of reduction in the optical power, and ultimately in sensitivity, per channel. In this work we have developed a new interferometric approach to overcome this signal loss by using high-power bursts that are synchronized with the time window in which ultrasound detection is performed. Each burst is composed of a train of low-noise optical pulses which are sufficiently wideband to interrogate an array of resonators with non-overlapping spectra. We demonstrate our method, termed burst-mode pulse interferometry, for interrogating a single resonator in which the optical power was reduced to emulate the power loss per channel that occurs in parallel interrogation of 20 to 200 resonators. The use of bursts has led to up 25-fold improvement in sensitivity without affecting the shape of the acoustic signals, potentially enabling parallel low-noise interrogation of resonator arrays with a single source.
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Alles EJ, Mackle EC, Noimark S, Zhang EZ, Beard PC, Desjardins AE. Freehand and video-rate all-optical ultrasound imaging. ULTRASONICS 2021; 116:106514. [PMID: 34280811 PMCID: PMC7611777 DOI: 10.1016/j.ultras.2021.106514] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 04/30/2021] [Accepted: 06/30/2021] [Indexed: 06/13/2023]
Abstract
All-optical ultrasound (AOUS) imaging, which uses light to both generate and detect ultrasound, is an emerging alternative to conventional electronic ultrasound imaging. To date, AOUS imaging has been performed using paradigms that either resulted in long acquisition times or employed bench-top imaging systems that were impractical for clinical use. In this work, we present a novel AOUS imaging paradigm where scanning optics are used to rapidly synthesise an imaging aperture. This paradigm enabled the first AOUS system with a flexible, handheld imaging probe, which represents a critical step towards clinical translation. This probe, which provides video-rate imaging and a real-time display, is demonstrated with phantoms and in vivo human tissue.
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Affiliation(s)
- Erwin J Alles
- Department of Medical Physics & Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom; Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 43-45 Foley Street, London W1W 7TS, United Kingdom.
| | - Eleanor C Mackle
- Department of Medical Physics & Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom; Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 43-45 Foley Street, London W1W 7TS, United Kingdom
| | - Sacha Noimark
- Department of Medical Physics & Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom; Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 43-45 Foley Street, London W1W 7TS, United Kingdom
| | - Edward Z Zhang
- Department of Medical Physics & Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom; Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 43-45 Foley Street, London W1W 7TS, United Kingdom
| | - Paul C Beard
- Department of Medical Physics & Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom; Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 43-45 Foley Street, London W1W 7TS, United Kingdom
| | - Adrien E Desjardins
- Department of Medical Physics & Biomedical Engineering, University College London, Malet Place Engineering Building, London WC1E 6BT, United Kingdom; Wellcome/EPSRC Centre for Interventional and Surgical Sciences, University College London, Charles Bell House, 43-45 Foley Street, London W1W 7TS, United Kingdom
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Grillo Peternella F, Harmsma P, Horsten RC, Zuidwijk T, Urbach HP, Adam AJL. Algebraic solutions for the Fourier transform interrogator. OPTICS EXPRESS 2021; 29:25632-25662. [PMID: 34614890 DOI: 10.1364/oe.426544] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Accepted: 07/04/2021] [Indexed: 06/13/2023]
Abstract
A new method for fast, high resolution interrogation of an array of photonic sensors is proposed. The technique is based on the integrated Fourier transform (FT) interrogator previously introduced by the authors. Compared to other interferometric interrogators, the FT-interrogator is very compact and has an unprecedented tolerance to variations in the nominal values of the sensors' resonance wavelength. In this paper, the output voltages of the interrogator are written as a polynomial function of complex variables whose modulus is unitary and whose argument encodes the resonance wavelength modulation of the photonic sensors. Two different methods are proposed to solve the system of polynomial equations. In both cases, the Gröbner basis of the polynomial ideal is computed using lexicographical monomial ordering, resulting in a system of polynomials whose complex variable contributions can be decoupled. Using an NVidia graphics processing card, the processing time for 1 026 000 systems of algebraic equations takes around 9 ms, which is more than two orders of magnitude faster than the interrogation method previously introduced by the authors. Such a performance allows for real time interrogation of high-speed sensors. Multiple solutions satisfy the algebraic system of equations, but, in general, only one of the solutions gives the actual resonance wavelength modulation of the sensors. Other solutions have been used for optimization, leading to a reduction in the cross-talk among the sensors. The dynamic strain resolution is 1.66 n ε/H z.
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Alles EJ, Desjardins AE. Source Density Apodization: Image Artifact Suppression Through Source Pitch Nonuniformity. IEEE TRANSACTIONS ON ULTRASONICS, FERROELECTRICS, AND FREQUENCY CONTROL 2020; 67:497-504. [PMID: 31603778 PMCID: PMC7049469 DOI: 10.1109/tuffc.2019.2945636] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Conventional ultrasound imaging probes typically comprise finite-sized arrays of periodically spaced transducer elements which, in the case of phased arrays, can result in severe grating and sidelobe artifacts. Whereas side lobes can be effectively suppressed through amplitude apodization ("AmpA"), grating lobes arising from periodicity in transducer placement can only be suppressed by decreasing the element pitch, which is technologically challenging and costly. In this work, we present source density apodization ("SDA") as an alternative apodization scheme, where the spatial source density (and, hence, the element pitch) is varied across the imaging aperture. Using an all-optical ultrasound imaging setup capable of video-rate 2-D imaging as well as dynamic and arbitrary reconfiguration of the source array geometry, we show both numerically and experimentally how SDA and AmpA are equivalent for large numbers of sources. For low numbers of sources, SDA is shown to yield superior image quality as both side and grating lobes are effectively suppressed. In addition, we demonstrate how asymmetric SDA schemes can be used to locally and dynamically improve the image quality. Finally, we demonstrate how a nonsmoothly varying spatial source density (such as that obtained for randomized arrays or in the presence of source positioning uncertainty or inaccuracy) can yield severe image artifacts. The application of SDA can, thus, yield high image quality even for low channel counts, which can ultimately result in higher imaging frame rates using acquisition systems of reduced complexity.
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Zhu J, Liu X, Shi Q, He T, Sun Z, Guo X, Liu W, Sulaiman OB, Dong B, Lee C. Development Trends and Perspectives of Future Sensors and MEMS/NEMS. MICROMACHINES 2019; 11:E7. [PMID: 31861476 PMCID: PMC7019281 DOI: 10.3390/mi11010007] [Citation(s) in RCA: 74] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/03/2019] [Revised: 12/11/2019] [Accepted: 12/12/2019] [Indexed: 01/24/2023]
Abstract
With the fast development of the fifth-generation cellular network technology (5G), the future sensors and microelectromechanical systems (MEMS)/nanoelectromechanical systems (NEMS) are presenting a more and more critical role to provide information in our daily life. This review paper introduces the development trends and perspectives of the future sensors and MEMS/NEMS. Starting from the issues of the MEMS fabrication, we introduced typical MEMS sensors for their applications in the Internet of Things (IoTs), such as MEMS physical sensor, MEMS acoustic sensor, and MEMS gas sensor. Toward the trends in intelligence and less power consumption, MEMS components including MEMS/NEMS switch, piezoelectric micromachined ultrasonic transducer (PMUT), and MEMS energy harvesting were investigated to assist the future sensors, such as event-based or almost zero-power. Furthermore, MEMS rigid substrate toward NEMS flexible-based for flexibility and interface was discussed as another important development trend for next-generation wearable or multi-functional sensors. Around the issues about the big data and human-machine realization for human beings' manipulation, artificial intelligence (AI) and virtual reality (VR) technologies were finally realized using sensor nodes and its wave identification as future trends for various scenarios.
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Affiliation(s)
- Jianxiong Zhu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore; (J.Z.); (X.L.); (Q.S.); (T.H.); (Z.S.); (X.G.); (W.L.); (O.B.S.); (B.D.)
- Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore 117608, Singapore
- Hybrid-Integrated Flexible (Stretchable) Electronic Systems Program, National University of Singapore, Singapore 117608, Singapore
- NUS Suzhou Research Institute (NUSRI), Suzhou Industrial Park, Suzhou 215123, China
| | - Xinmiao Liu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore; (J.Z.); (X.L.); (Q.S.); (T.H.); (Z.S.); (X.G.); (W.L.); (O.B.S.); (B.D.)
- Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore 117608, Singapore
- Hybrid-Integrated Flexible (Stretchable) Electronic Systems Program, National University of Singapore, Singapore 117608, Singapore
| | - Qiongfeng Shi
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore; (J.Z.); (X.L.); (Q.S.); (T.H.); (Z.S.); (X.G.); (W.L.); (O.B.S.); (B.D.)
- Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore 117608, Singapore
- Hybrid-Integrated Flexible (Stretchable) Electronic Systems Program, National University of Singapore, Singapore 117608, Singapore
- NUS Suzhou Research Institute (NUSRI), Suzhou Industrial Park, Suzhou 215123, China
| | - Tianyiyi He
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore; (J.Z.); (X.L.); (Q.S.); (T.H.); (Z.S.); (X.G.); (W.L.); (O.B.S.); (B.D.)
- Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore 117608, Singapore
- Hybrid-Integrated Flexible (Stretchable) Electronic Systems Program, National University of Singapore, Singapore 117608, Singapore
- NUS Suzhou Research Institute (NUSRI), Suzhou Industrial Park, Suzhou 215123, China
| | - Zhongda Sun
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore; (J.Z.); (X.L.); (Q.S.); (T.H.); (Z.S.); (X.G.); (W.L.); (O.B.S.); (B.D.)
- Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore 117608, Singapore
- Hybrid-Integrated Flexible (Stretchable) Electronic Systems Program, National University of Singapore, Singapore 117608, Singapore
| | - Xinge Guo
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore; (J.Z.); (X.L.); (Q.S.); (T.H.); (Z.S.); (X.G.); (W.L.); (O.B.S.); (B.D.)
- Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore 117608, Singapore
- Hybrid-Integrated Flexible (Stretchable) Electronic Systems Program, National University of Singapore, Singapore 117608, Singapore
| | - Weixin Liu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore; (J.Z.); (X.L.); (Q.S.); (T.H.); (Z.S.); (X.G.); (W.L.); (O.B.S.); (B.D.)
- Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore 117608, Singapore
- Hybrid-Integrated Flexible (Stretchable) Electronic Systems Program, National University of Singapore, Singapore 117608, Singapore
| | - Othman Bin Sulaiman
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore; (J.Z.); (X.L.); (Q.S.); (T.H.); (Z.S.); (X.G.); (W.L.); (O.B.S.); (B.D.)
- Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore 117608, Singapore
- Hybrid-Integrated Flexible (Stretchable) Electronic Systems Program, National University of Singapore, Singapore 117608, Singapore
| | - Bowei Dong
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore; (J.Z.); (X.L.); (Q.S.); (T.H.); (Z.S.); (X.G.); (W.L.); (O.B.S.); (B.D.)
- Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore 117608, Singapore
- Hybrid-Integrated Flexible (Stretchable) Electronic Systems Program, National University of Singapore, Singapore 117608, Singapore
- NUS Suzhou Research Institute (NUSRI), Suzhou Industrial Park, Suzhou 215123, China
- NUS Graduate School for Integrative Science and Engineering (NGS), National University of Singapore, Singapore 119077, Singapore
| | - Chengkuo Lee
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117583, Singapore; (J.Z.); (X.L.); (Q.S.); (T.H.); (Z.S.); (X.G.); (W.L.); (O.B.S.); (B.D.)
- Center for Intelligent Sensors and MEMS (CISM), National University of Singapore, Singapore 117608, Singapore
- Hybrid-Integrated Flexible (Stretchable) Electronic Systems Program, National University of Singapore, Singapore 117608, Singapore
- NUS Suzhou Research Institute (NUSRI), Suzhou Industrial Park, Suzhou 215123, China
- NUS Graduate School for Integrative Science and Engineering (NGS), National University of Singapore, Singapore 119077, Singapore
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Kalaswad M, Zhang D, Gao X, Contreras LL, Wang H, Wang X, Wang H. Integration of Hybrid Plasmonic Au-BaTiO 3 Metamaterial on Silicon Substrates. ACS APPLIED MATERIALS & INTERFACES 2019; 11:45199-45206. [PMID: 31701734 DOI: 10.1021/acsami.9b15528] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/18/2023]
Abstract
Silicon integration of nanoscale metamaterials is a crucial step toward low-cost and scalable optical-based integrated circuits. Here, a self-assembled epitaxial Au-BaTiO3 (Au-BTO) hybrid metamaterial with highly anisotropic optical properties has been integrated on Si substrates. A thin buffer layer stack (<20 nm) of TiN and SrTiO3 (STO) was applied on Si substrates to ensure the epitaxial growth of the Au-BTO hybrid films. Detailed phase composition and microstructural analyses show excellent crystallinity and epitaxial quality of the Au-BTO films. By varying the film growth conditions, the density and dimension of the Au nanopillars can be tuned effectively, leading to highly tailorable optical properties including tunable localized surface plasmon resonance (LSPR) peak and hyperbolic dispersion shift in the visible and near-infrared regimes. The work highlights the feasibility of integrating epitaxial hybrid oxide-metal plasmonic metamaterials on Si toward future complex Si-based integrated photonics.
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Hazan Y, Rosenthal A. Simultaneous multi-channel ultrasound detection via phase modulated pulse interferometry. OPTICS EXPRESS 2019; 27:28844-28854. [PMID: 31684629 DOI: 10.1364/oe.27.028844] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Accepted: 09/13/2019] [Indexed: 06/10/2023]
Abstract
In optical detection of ultrasound, resonators with high Q-factors are often used to maximize sensitivity. However, in order to perform parallel interrogation, conventional interferometric techniques require an overlap between the spectra of all the resonators, which is difficult to achieve with high Q-factor resonators. In this paper, a new method is developed for parallel interrogation of optical resonators with non-overlapping spectra. The method is based on a phase-modulation scheme for pulse interferometry (PM-PI) and requires only a single photodetector and sampling channel per ultrasound detector. Using PM-PI, parallel ultrasound detection is demonstrated with four high Q-factor resonators.
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Ouyang B, Haverdings M, Horsten R, Kruidhof M, Kat P, Caro J. Integrated photonics interferometric interrogator for a ring-resonator ultrasound sensor. OPTICS EXPRESS 2019; 27:23408-23421. [PMID: 31510622 DOI: 10.1364/oe.27.023408] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 07/20/2019] [Indexed: 06/10/2023]
Abstract
We present a compact integrated photonics interrogator for a ring-resonator (RR) ultrasound sensor, the so-called MediGator. The MediGator consists of a special light source and an InP Mach-Zehnder interferometer (MZI) with a 3 ×3 multi-mode interferometer. Miniaturization of the MZI to chip size enables high temperature stability and negligible signal drift. The light source has a -3 dB bandwidth of 1.5 nm, a power density of 9 dBm/nm and a tuning range of 5.7 nm, providing sufficient signal level and robust alignment for the RR sensor. The mathematical procedure of interrogation is presented, leading to the optimum MZI design. We measure the frequency response of the sensor using the MediGator, giving a resonance frequency of 0.995MHz. Further, high interrogation performance is demonstrated at the RR resonance frequency for an ultrasound pressure range of 1.47 - 442.4 Pa, which yields very good linearity between the pressure and the resulting modulation amplitude of the RR resonance wavelength. The measured signal time traces match well with calculated results. Linear fitting of the pressure data gives a sensor sensitivity of 77.2 fm/Pa. The MediGator provides a low detection limit, temperature robustness and a large measurement range for interrogating the RR ultrasound sensor.
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Zhu EY, Rewcastle C, Gad R, Qian L, Levi O. Refractive-index-based ultrasound sensing with photonic crystal slabs. OPTICS LETTERS 2019; 44:2609-2612. [PMID: 31090744 DOI: 10.1364/ol.44.002609] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Accepted: 04/26/2019] [Indexed: 06/09/2023]
Abstract
We demonstrate ultrasound detection with 500-μm-diameter photonic-crystal slab (PCS) sensors fabricated from CMOS-compatible technology. An ultrasound signal impinging a PCS sensor causes a local modulation of the refractive index (RI) of the medium (water) in which the PCS is immersed, resulting in a periodic spectral shift of the optical resonance of the PCS. The acoustic sensitivity is found to scale with the index sensitivity S and quality factor Q. A noise equivalent pressure (NEP) of 650 Pa with averaging (7.4 Pa/Hz) and relative wavelength shifts of up to 4.3×10-5 MPa-1 are measured. The frequency response of the sensors is observed to be flat from 1 to 20 MHz, with the range limited only by our measurement apparatus.
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Ouyang B, Li Y, Kruidhof M, Horsten R, van Dongen KWA, Caro J. On-chip silicon Mach-Zehnder interferometer sensor for ultrasound detection. OPTICS LETTERS 2019; 44:1928-1931. [PMID: 30985777 DOI: 10.1364/ol.44.001928] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2019] [Accepted: 03/02/2019] [Indexed: 06/09/2023]
Abstract
A highly sensitive ultrasound sensor based on an integrated photonics Mach-Zehnder interferometer (MZI) fabricated in silicon-on-insulator technology is reported. The sensing spiral is located on a membrane of size 121 μm×121 μm. Ultrasound waves excite the membrane's vibrational mode, which translates to modulation of the MZI transmission. The measured sensor transfer function is centered at 0.47 MHz and has a -6 dB bandwidth of 21.2%. The sensor sensitivity is linear in the optical input power and reaches a maximum 0.62 mV/Pa, which is limited by the interrogation method. At 0.47 MHz and for an optical power of 1.0 mW the detection limit is 0.38 mPa/Hz1/2 and the dynamic range is 59 dB. The MZI's gradual transmission function allows a wide range of wavelength operation points. This strongly facilitates sensor use and is promising for applications.
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15
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Abel S, Eltes F, Ortmann JE, Messner A, Castera P, Wagner T, Urbonas D, Rosa A, Gutierrez AM, Tulli D, Ma P, Baeuerle B, Josten A, Heni W, Caimi D, Czornomaz L, Demkov AA, Leuthold J, Sanchis P, Fompeyrine J. Large Pockels effect in micro- and nanostructured barium titanate integrated on silicon. NATURE MATERIALS 2019; 18:42-47. [PMID: 30420671 DOI: 10.1038/s41563-018-0208-0] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 09/26/2018] [Indexed: 05/14/2023]
Abstract
The electro-optical Pockels effect is an essential nonlinear effect used in many applications. The ultrafast modulation of the refractive index is, for example, crucial to optical modulators in photonic circuits. Silicon has emerged as a platform for integrating such compact circuits, but a strong Pockels effect is not available on silicon platforms. Here, we demonstrate a large electro-optical response in silicon photonic devices using barium titanate. We verify the Pockels effect to be the physical origin of the response, with r42 = 923 pm V-1, by confirming key signatures of the Pockels effect in ferroelectrics: the electro-optic response exhibits a crystalline anisotropy, remains strong at high frequencies, and shows hysteresis on changing the electric field. We prove that the Pockels effect remains strong even in nanoscale devices, and show as a practical example data modulation up to 50 Gbit s-1. We foresee that our work will enable novel device concepts with an application area largely extending beyond communication technologies.
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Affiliation(s)
- Stefan Abel
- IBM Research-Zurich, Rüschlikon, Switzerland.
| | - Felix Eltes
- IBM Research-Zurich, Rüschlikon, Switzerland
| | | | - Andreas Messner
- ETH Zurich, Institute of Electromagnetic Fields (IEF), Zürich, Switzerland
| | - Pau Castera
- Nanophotonics Technology Center, Universitat Politècnica València, Valencia, Spain
| | - Tino Wagner
- ETH Zurich, Nanotechnology Group, Rüschlikon, Switzerland
| | | | - Alvaro Rosa
- Nanophotonics Technology Center, Universitat Politècnica València, Valencia, Spain
| | - Ana M Gutierrez
- Nanophotonics Technology Center, Universitat Politècnica València, Valencia, Spain
| | - Domenico Tulli
- DAS Photonics, Universitat Politècnica València, Valencia, Spain
| | - Ping Ma
- ETH Zurich, Institute of Electromagnetic Fields (IEF), Zürich, Switzerland.
| | - Benedikt Baeuerle
- ETH Zurich, Institute of Electromagnetic Fields (IEF), Zürich, Switzerland
| | - Arne Josten
- ETH Zurich, Institute of Electromagnetic Fields (IEF), Zürich, Switzerland
| | - Wolfgang Heni
- ETH Zurich, Institute of Electromagnetic Fields (IEF), Zürich, Switzerland
| | | | | | | | - Juerg Leuthold
- ETH Zurich, Institute of Electromagnetic Fields (IEF), Zürich, Switzerland
| | - Pablo Sanchis
- Nanophotonics Technology Center, Universitat Politècnica València, Valencia, Spain.
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16
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Naesby A, Dantan A. Microcavities with suspended subwavelength structured mirrors. OPTICS EXPRESS 2018; 26:29886-29894. [PMID: 30469947 DOI: 10.1364/oe.26.029886] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2018] [Accepted: 10/24/2018] [Indexed: 06/09/2023]
Abstract
We investigate the optical properties of microcavities with suspended subwavelength structured mirrors, such as high-contrast gratings or two-dimensional photonic crystals slabs, and focus in particular on the regime in which the microcavity free-spectral range is larger than the width of a Fano resonance of the highly reflecting structured mirror. In this unusual regime, the transmission spectrum of the microcavity essentially consists in a single mode, whose linewidth can be significantly narrower than both the Fano resonance linewidth and the linewidth of an equally short cavity without structured mirror. This generic interference effect-occuring in any Fabry-Perot resonator with a strongly wavelength-dependent mirror-can be exploited for realizing small modevolume and high quality factor microcavities and, if high mechanical quality suspended structured thin films are used, for optomechanics and optical sensing applications.
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17
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Hänsel A, Heck MJR. Feasibility of Telecom-Wavelength Photonic Integrated Circuits for Gas Sensors. SENSORS 2018; 18:s18092870. [PMID: 30200292 PMCID: PMC6164772 DOI: 10.3390/s18092870] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 08/16/2018] [Accepted: 08/26/2018] [Indexed: 12/03/2022]
Abstract
To be of commercial interest, gas sensors must optimise, among others, sensitivity, selectivity, longevity, cost and measurement speed. Using the example of ammonia, we establish that integrated optical sensors provide means to maintain the benefits of optical detection set-ups at, in principle, a lower cost and smaller footprint than currently available commercial products. Photonic integrated circuits (PICs) can be used in environmental and agricultural monitoring. The small footprint and great cost scaling of PICs allow for sensor networks with multiple devices. We show, that Indium Phosphide based commercial foundries reached the technological maturity to enable ammonia detection levels at less than 100 ppb. The current unavailability of portable, low cost ammonia sensors with such detection levels prevents emission monitoring, for example, in pig farms. The feasibility of these sensors is investigated by applying the common noise figures of the multiproject wafer platforms operating around 1550 nm to a model for an absorption measurement. The analysis is extended to other relevant gas species with absorption features near telecom-wavelengths.
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Affiliation(s)
- Andreas Hänsel
- Department of Engineering, Aarhus University, Finlandsgade 22, 8200 Aarhus, Denmark.
| | - Martijn J R Heck
- Department of Engineering, Aarhus University, Finlandsgade 22, 8200 Aarhus, Denmark.
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18
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Volodarsky O, Hazan Y, Rosenthal A. Ultrasound detection via low-noise pulse interferometry using a free-space Fabry-Pérot. OPTICS EXPRESS 2018; 26:22405-22418. [PMID: 30130935 DOI: 10.1364/oe.26.022405] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 07/16/2018] [Indexed: 06/08/2023]
Abstract
Coherence-restored pulse interferometry (CRPI) is a recently developed method for optical detection of ultrasound that achieves shot-noise-limited sensitivity and high dynamic range. In principle, the wideband source employed in CRPI may enable the interrogation of multiple detectors by using wavelength multiplexing. However, the noise-reduction scheme in CRPI has not been shown to be compatible with wideband operation. In this work, we introduce a new scheme for CRPI that relies on a free-space Fabry-Pérot filter for noise reduction and a pulse stretcher for reducing nonlinear effects. Using our scheme, we demonstrate that shot-noise-limited detection may be achieved for a spectral band of 80 nm and powers of up to 5 mW.
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19
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Alles EJ, Noimark S, Maneas E, Zhang EZ, Parkin IP, Beard PC, Desjardins AE. Video-rate all-optical ultrasound imaging. BIOMEDICAL OPTICS EXPRESS 2018; 9:3481-3494. [PMID: 30338133 PMCID: PMC6191631 DOI: 10.1364/boe.9.003481] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2018] [Revised: 06/01/2018] [Accepted: 06/06/2018] [Indexed: 05/16/2023]
Abstract
All-optical ultrasound imaging, where ultrasound is generated and detected using light, has recently been demonstrated as a viable modality that is inherently insensitive to electromagnetic interference and exhibits wide bandwidths. High-quality 2D and 3D all-optical ultrasound images of tissues have previously been presented; however, to date, long acquisition times (ranging from minutes to hours) have hindered clinical application. Here, we present the first all-optical ultrasound imaging system capable of video-rate, real-time two-dimensional imaging of biological tissue. This was achieved using a spatially extended nano-composite optical ultrasound generator, a highly sensitive fibre-optic acoustic receiver, and eccentric illumination resulting in an acoustic source exhibiting optimal directivity. This source was scanned across a one-dimensional source aperture using a fast galvo mirror, thus enabling the dynamic synthesis of source arrays comprising spatially overlapping sources at non-uniform source separation distances. The resulting system achieved a sustained frame rate of 15 Hz, a dynamic range of 30 dB, a penetration depth of at least 6 mm, a resolution of 75 µm (axial) by 100 µm (lateral), and enabled the dynamics of a pulsating ex vivo carotid artery to be captured.
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Affiliation(s)
- Erwin J. Alles
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT,
UK
- Wellcome / EPSRC Centre for Surgical and Interventional Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
| | - Sacha Noimark
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT,
UK
- Wellcome / EPSRC Centre for Surgical and Interventional Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
- Materials Chemistry Research Centre, UCL Department of Chemistry, London WC1H 0AJ, UK
| | - Efthymios Maneas
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT,
UK
- Wellcome / EPSRC Centre for Surgical and Interventional Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
| | - Edward Z. Zhang
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT,
UK
| | - Ivan P. Parkin
- Wellcome / EPSRC Centre for Surgical and Interventional Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
- Materials Chemistry Research Centre, UCL Department of Chemistry, London WC1H 0AJ, UK
| | - Paul C. Beard
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT,
UK
- Wellcome / EPSRC Centre for Surgical and Interventional Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT,
UK
- Wellcome / EPSRC Centre for Surgical and Interventional Sciences, University College London, Charles Bell House, 67-73 Riding House Street, London W1W 7EJ,
UK
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20
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Castellan C, Chalyan A, Mancinelli M, Guilleme P, Borghi M, Bosia F, Pugno NM, Bernard M, Ghulinyan M, Pucker G, Pavesi L. Tuning the strain-induced resonance shift in silicon racetrack resonators by their orientation. OPTICS EXPRESS 2018; 26:4204-4218. [PMID: 29475273 DOI: 10.1364/oe.26.004204] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 12/24/2017] [Indexed: 06/08/2023]
Abstract
In this work, we analyze the role of strain on a set of silicon racetrack resonators presenting different orientations with respect to the applied strain. The strain induces a variation of the resonance wavelength, caused by the photoelastic variation of the material refractive index as well as by the mechanical deformation of the device. In particular, the mechanical deformation alters both the resonator perimeter and the waveguide cross-section. Finite element simulations taking into account all these effects are presented, providing good agreement with experimental results. By studying the role of the resonator orientation we identify interesting features, such as the tuning of the resonance shift from negative to positive values and the possibility of realizing strain insensitive devices.
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21
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Tsesses S, Aronovich D, Grinberg A, Hahamovich E, Rosenthal A. Modeling the sensitivity dependence of silicon-photonics-based ultrasound detectors. OPTICS LETTERS 2017; 42:5262-5265. [PMID: 29240188 DOI: 10.1364/ol.42.005262] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 11/17/2017] [Indexed: 06/07/2023]
Abstract
With recent advances in optical technology, interferometric sensing has grown into a highly versatile approach for ultrasound detection, with many interferometric detectors relying on optical waveguides to achieve high levels of sensitivity and miniaturization. In this Letter, we establish a practical model for assessing the sensitivity of silicon-photonics waveguides to acoustic waves. The analysis is performed for different polarizations, waveguide dimensions, and acoustic wave types. Our model was validated experimentally in the acoustic frequency band of 1-13 MHz by measuring the sensitivities of the two polarization modes in a silicon strip waveguide. Both the experimental results and theoretical prediction show that the transverse-magnetic polarization achieves a higher sensitivity and suppression of surface acoustic waves compared to the transverse-electric polarization for the geometries studied.
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22
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Peternella FG, Ouyang B, Horsten R, Haverdings M, Kat P, Caro J. Interrogation of a ring-resonator ultrasound sensor using a fiber Mach-Zehnder interferometer. OPTICS EXPRESS 2017; 25:31622-31639. [PMID: 29245834 DOI: 10.1364/oe.25.031622] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/20/2017] [Accepted: 11/22/2017] [Indexed: 06/07/2023]
Abstract
We experimentally demonstrate an interrogation procedure of a ring-resonator ultrasound sensor using a fiber Mach-Zehnder interferometer (MZI). The sensor comprises a silicon ring resonator (RR) located on a silicon-oxide membrane, designed to have its lowest vibrational mode in the MHz range, which is the range of intravascular ultrasound (IVUS) imaging. Ultrasound incident on the membrane excites its vibrational mode and as a result induces a modulation of the resonance wavelength of the RR, which is a measure of the amplitude of the ultrasound waves. The interrogation procedure developed is based on the mathematical description of the interrogator operation presented in Appendix A, where we identify the amplitude of the angular deflection Φ0 on the circle arc periodically traced in the plane of the two orthogonal interrogator voltages, as the principal sensor signal. Interrogation is demonstrated for two sensors with membrane vibrational modes at 1.3 and 0.77 MHz, by applying continuous wave ultrasound in a wide pressure range. Ultrasound is detected at a pressure as low as 1.2 Pa. Two optical path differences (OPDs) of the MZI are used. Thus, different interference conditions of the optical signals are defined, leading to a higher apparent sensitivity for the larger OPD, which is accompanied by a weaker signal, however. Independent measurements using the modulation method yield a resonance modulation per unit of pressure of 21.4 fm/Pa (sensor #1) and 103.8 fm/Pa (sensor #2).
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23
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Bai X, Liang Y, Sun H, Jin L, Ma J, Guan BO, Wang L. Sensitivity characteristics of broadband fiber-laser-based ultrasound sensors for photoacoustic microscopy. OPTICS EXPRESS 2017; 25:17616-17626. [PMID: 28789254 DOI: 10.1364/oe.25.017616] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Accepted: 07/10/2017] [Indexed: 05/24/2023]
Abstract
High-frequency fiber laser sensor is a new acoustic detector for photoacoustic imaging. However, its performance has not been thoroughly studied. Here, we present a comprehensive characterization of a fiber laser sensor for photoacoustic imaging. Ultrasound waves deform the fiber laser cavity and induce frequency changes in the heterodyning output signal. The sensitivity peaks at 22 MHz, which is associated with an azimuthal mode number l = 2 and a radial mode number n = 1. The broadband acoustic sensitivity in terms of frequency shift is 2.25 MHz/kPa and the noise-equivalent pressure reaches 45 Pa with a sampling rate of 100 MHz. The 3-dB bandwidth is 18 MHz for spherical-wave detection. We characterized the spatial distribution of acoustic sensitivity. The sensitivity along the fiber longitudinal direction varies with the laser spatial mode and is determined by the grating and cavity parameters. The sensitivity at the azimuthal direction presents a |cos(2θ)| dependence as a result of fiber core asymmetry. In the radial direction, the sensitivity is inversely proportional to the square root of the distance between the source and the detector. The acoustic sensitivity can be enhanced by reducing the cavity length. We experimentally show that a short sensor can enhance the contrast and penetration depth of PAM than a long one.
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24
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Alles EJ, Fook Sheung N, Noimark S, Zhang EZ, Beard PC, Desjardins AE. A reconfigurable all-optical ultrasound transducer array for 3D endoscopic imaging. Sci Rep 2017; 7:1208. [PMID: 28446784 PMCID: PMC5430692 DOI: 10.1038/s41598-017-01375-2] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2016] [Accepted: 03/29/2017] [Indexed: 11/13/2022] Open
Abstract
A miniature all-optical ultrasound imaging system is presented that generates three-dimensional images using a stationary, real acoustic source aperture. Discrete acoustic sources were sequentially addressed by scanning a focussed optical beam across the proximal end of a coherent fibre bundle; high-frequency ultrasound (156% fractional bandwidth centred around 13.5 MHz) was generated photoacoustically in the corresponding regions of an optically absorbing coating deposited at the distal end. Paired with a single fibre-optic ultrasound detector, the imaging probe (3.5 mm outer diameter) achieved high on-axis resolutions of 97 μm, 179 μm and 110 μm in the x, y and z directions, respectively. Furthermore, the optical scan pattern, and thus the acoustic source array geometry, was readily reconfigured. Implementing four different array geometries revealed a strong dependency of the image quality on the source location pattern. Thus, by employing optical technology, a miniature ultrasound probe was fabricated that allows for arbitrary source array geometries, which is suitable for three-dimensional endoscopic and laparoscopic imaging, as was demonstrated on ex vivo porcine cardiac tissue.
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Affiliation(s)
- Erwin J Alles
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK.
| | - Nora Fook Sheung
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK
| | - Sacha Noimark
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK
- Materials Chemistry Research Centre, UCL Department of Chemistry, London, WC1H 0AJ, UK
| | - Edward Z Zhang
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK
| | - Paul C Beard
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK
| | - Adrien E Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, London, WC1E 6BT, UK
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25
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Kim KH, Luo W, Zhang C, Tian C, Guo LJ, Wang X, Fan X. Air-coupled ultrasound detection using capillary-based optical ring resonators. Sci Rep 2017; 7:109. [PMID: 28250443 PMCID: PMC5427941 DOI: 10.1038/s41598-017-00134-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 02/09/2017] [Indexed: 11/20/2022] Open
Abstract
We experimentally demonstrate and theoretically analyze high Q-factor (~107) capillary-based optical ring resonators for non-contact detection of air-coupled ultrasound. Noise equivalent pressures in air as low as 215 mPa/√Hz and 41 mPa/√Hz at 50 kHz and 800 kHz in air, respectively, are achieved. Furthermore, non-contact detection of air-coupled photoacoustic pulses optically generated from a 200 nm thick Chromium film is demonstrated. The interaction of an acoustic pulse and the mechanical mode of the ring resonator is also studied. Significant improvement in detection bandwidth is demonstrated by encapsulating the ring resonator in a damping medium. Our work will enable compact and sensitive ultrasound detection in many applications, such as air-coupled non-destructive ultrasound testing, photoacoustic imaging, and remote sensing. It will also provide a model system for fundamental study of the mechanical modes in the ring resonator.
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Affiliation(s)
- Kyu Hyun Kim
- Department of Biomedical Engineering, University of Michigan, 1101 Beal Ave., Ann Arbor, MI, 48109, USA
- Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, MI, 48109, USA
| | - Wei Luo
- Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, MI, 48109, USA
- School of Optical and Electrical Information, Huazhong University of Science and Technology, 1037 Luoyu Road, Hongshan District, 430074, Wuhan, Hubei, PR China
| | - Cheng Zhang
- Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, MI, 48109, USA
| | - Chao Tian
- Department of Biomedical Engineering, University of Michigan, 1101 Beal Ave., Ann Arbor, MI, 48109, USA
| | - L Jay Guo
- Department of Electrical Engineering and Computer Science, University of Michigan, 1301 Beal Ave., Ann Arbor, MI, 48109, USA
| | - Xueding Wang
- Department of Biomedical Engineering, University of Michigan, 1101 Beal Ave., Ann Arbor, MI, 48109, USA
| | - Xudong Fan
- Department of Biomedical Engineering, University of Michigan, 1101 Beal Ave., Ann Arbor, MI, 48109, USA.
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26
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Alles EJ, Noimark S, Zhang E, Beard PC, Desjardins AE. Pencil beam all-optical ultrasound imaging. BIOMEDICAL OPTICS EXPRESS 2016; 7:3696-3704. [PMID: 27699130 PMCID: PMC5030042 DOI: 10.1364/boe.7.003696] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Revised: 08/08/2016] [Accepted: 08/08/2016] [Indexed: 05/18/2023]
Abstract
A miniature, directional fibre-optic acoustic source is presented that employs geometrical focussing to generate a nearly-collimated acoustic pencil beam. When paired with a fibre-optic acoustic detector, an all-optical ultrasound probe with an outer diameter of 2.5 mm is obtained that acquires a pulse-echo image line at each probe position without the need for image reconstruction. B-mode images can be acquired by translating the probe and concatenating the image lines, and artefacts resulting from probe positioning uncertainty are shown to be significantly lower than those observed for conventional synthetic aperture scanning of a non-directional acoustic source. The high image quality obtained for excised vascular tissue suggests that the all-optical ultrasound probe is ideally suited for in vivo, interventional applications.
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Affiliation(s)
- Erwin J. Alles
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK
| | - Sacha Noimark
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK
- Materials Chemistry Research Centre, UCL Department of Chemistry, London WC1H 0AJ, UK
| | - Edward Zhang
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK
| | - Paul C. Beard
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK
| | - Adrien E. Desjardins
- Department of Medical Physics and Biomedical Engineering, University College London, London WC1E 6BT, UK
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