Zhen Liao, Chenhao Huang, Leilei Liu, K. Xu, Siyuan Luo, Baicao Pan, Jiusheng Li, Guo Qing Luo
Plasmonic skyrmions are a subject of significant interest due to their potential applications in optics, photonics, and electromagnetic wave technology. These skyrmions are created by the interference of surface plasmon polaritons or spoof localized surface plasmons (SLSP), offering new possibilities for controlling light–matter interactions and structuring light. In this study, we have demonstrated the generation of both electric and magnetic skyrmions simultaneously using a rotational symmetric SLSP spiral meta-structure lattice, operating across a broad range from microwave to terahertz frequencies. By implementing them into a resonance configuration of the quasi-bound state in the continuum through symmetry breaking, we enhance the Q factor and fields, resulting in highly sensitive sensing performance. The SLSP metasurface enables tunable plasmonic skyrmions controlled by the incident polarization. Our findings have potential applications in highly sensitive sensing, filtering, modulation, and communication.
{"title":"Plasmonic skyrmions with bound states in the continuum","authors":"Zhen Liao, Chenhao Huang, Leilei Liu, K. Xu, Siyuan Luo, Baicao Pan, Jiusheng Li, Guo Qing Luo","doi":"10.1063/5.0159404","DOIUrl":"https://doi.org/10.1063/5.0159404","url":null,"abstract":"Plasmonic skyrmions are a subject of significant interest due to their potential applications in optics, photonics, and electromagnetic wave technology. These skyrmions are created by the interference of surface plasmon polaritons or spoof localized surface plasmons (SLSP), offering new possibilities for controlling light–matter interactions and structuring light. In this study, we have demonstrated the generation of both electric and magnetic skyrmions simultaneously using a rotational symmetric SLSP spiral meta-structure lattice, operating across a broad range from microwave to terahertz frequencies. By implementing them into a resonance configuration of the quasi-bound state in the continuum through symmetry breaking, we enhance the Q factor and fields, resulting in highly sensitive sensing performance. The SLSP metasurface enables tunable plasmonic skyrmions controlled by the incident polarization. Our findings have potential applications in highly sensitive sensing, filtering, modulation, and communication.","PeriodicalId":8198,"journal":{"name":"APL Photonics","volume":" ","pages":""},"PeriodicalIF":5.6,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42674299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Femtosecond (Fs) laser micro-/nano-fabrication technology allows direct definition of on-demand nanostructures with three-dimensional (3D) geometric features and tailored photonic functionalities in a facile manner. In addition, such a strategy is widely applicable to various material families, including dielectrics, semiconductors, and metals. Based on diverse dielectric crystals, fs-laser direct writing of optical waveguides with flexible geometries and functional waveguide-based photonic devices have been well-developed. Beyond waveguide architectures, the combination of 3D nanofabrication of fs lasers and the multi-functionalities of dielectric crystals has also lighted up the future development of novel photonic structures with features even beyond the optical diffraction limit. In this article, promising research topics on domain engineering for nonlinear optics, color centers and waveguides for integrated quantum photonics, and surface processing for integrated photonics enabled by fs laser micro-/nano-fabrication in dielectric crystals are briefly overviewed. We highlight recent progress on these research topics and stress the importance of optical aberration correction during laser fabrication, followed by a discussion of challenges and foreseeing the future development of fs laser defined nanostructures in dielectric crystals toward multi-functional photonics.
{"title":"Recent progress on femtosecond laser micro-/nano-fabrication of functional photonic structures in dielectric crystals: A brief review and perspective","authors":"Yuechen Jia, F. Chen","doi":"10.1063/5.0160067","DOIUrl":"https://doi.org/10.1063/5.0160067","url":null,"abstract":"Femtosecond (Fs) laser micro-/nano-fabrication technology allows direct definition of on-demand nanostructures with three-dimensional (3D) geometric features and tailored photonic functionalities in a facile manner. In addition, such a strategy is widely applicable to various material families, including dielectrics, semiconductors, and metals. Based on diverse dielectric crystals, fs-laser direct writing of optical waveguides with flexible geometries and functional waveguide-based photonic devices have been well-developed. Beyond waveguide architectures, the combination of 3D nanofabrication of fs lasers and the multi-functionalities of dielectric crystals has also lighted up the future development of novel photonic structures with features even beyond the optical diffraction limit. In this article, promising research topics on domain engineering for nonlinear optics, color centers and waveguides for integrated quantum photonics, and surface processing for integrated photonics enabled by fs laser micro-/nano-fabrication in dielectric crystals are briefly overviewed. We highlight recent progress on these research topics and stress the importance of optical aberration correction during laser fabrication, followed by a discussion of challenges and foreseeing the future development of fs laser defined nanostructures in dielectric crystals toward multi-functional photonics.","PeriodicalId":8198,"journal":{"name":"APL Photonics","volume":" ","pages":""},"PeriodicalIF":5.6,"publicationDate":"2023-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41855031","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Microcavity lasers show excellent performance as a miniaturized microsensor in various applications. However, their relatively weak power may be easily submerged in system noises and disturbed by environmental fluctuations, rendering them ineffective at detecting small signals for precise sensing. To solve this problem, the laser differential frequency-shift feedback technique is demonstrated in a microtubule Raman laser to achieve the optical gain assistance. When the microlaser is frequency-shift-modulated and returns back to the resonator, the measurement signal can resonate with the laser relaxation oscillation and be significantly enhanced. The intracavity dynamics-based enhancement makes it effective for increasing intensity changes caused by analytes. Small signals that would otherwise be buried in system noises and go undetected can be more easily resolved. In addition, the microsensor reduces the spectral measurement range and offers a way to observe the fast dynamic response. Based on that, a measurement resolution of 50 nm nanoparticle detection limit and a refractive index noise-limited resolution of 8.18 × 10−7 refractive index unit (RIU) are demonstrated. The dynamic phase transition of thermosensitive hydrogel is further investigated as a validation of its rapid detection capability. Integrated with an inherent microfluidic channel, the proposed microsensor provides a direct interaction between analytes and probe light with ultrasmall sample consumption down to 50 pl. It is expected to boost the detection of weak signals in microlasers and enlighten the development of optofluidic microsensors in exploring diverse biochemical processes.
{"title":"Intracavity dynamics-based gain-assisted sensing with microtubule Raman microlaser","authors":"Mingfang Li, Zongren Dai, Mingwang Tian, Y. Tan","doi":"10.1063/5.0158302","DOIUrl":"https://doi.org/10.1063/5.0158302","url":null,"abstract":"Microcavity lasers show excellent performance as a miniaturized microsensor in various applications. However, their relatively weak power may be easily submerged in system noises and disturbed by environmental fluctuations, rendering them ineffective at detecting small signals for precise sensing. To solve this problem, the laser differential frequency-shift feedback technique is demonstrated in a microtubule Raman laser to achieve the optical gain assistance. When the microlaser is frequency-shift-modulated and returns back to the resonator, the measurement signal can resonate with the laser relaxation oscillation and be significantly enhanced. The intracavity dynamics-based enhancement makes it effective for increasing intensity changes caused by analytes. Small signals that would otherwise be buried in system noises and go undetected can be more easily resolved. In addition, the microsensor reduces the spectral measurement range and offers a way to observe the fast dynamic response. Based on that, a measurement resolution of 50 nm nanoparticle detection limit and a refractive index noise-limited resolution of 8.18 × 10−7 refractive index unit (RIU) are demonstrated. The dynamic phase transition of thermosensitive hydrogel is further investigated as a validation of its rapid detection capability. Integrated with an inherent microfluidic channel, the proposed microsensor provides a direct interaction between analytes and probe light with ultrasmall sample consumption down to 50 pl. It is expected to boost the detection of weak signals in microlasers and enlighten the development of optofluidic microsensors in exploring diverse biochemical processes.","PeriodicalId":8198,"journal":{"name":"APL Photonics","volume":" ","pages":""},"PeriodicalIF":5.6,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45623743","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Photonic integrated circuits (PICs) allow for the rapid advancement of a wide range of optical devices on a compact platform, making them more useful and readily available in the commercial market. Various materials such as III–V semiconductors, silicon, silicon nitride, lithium niobate, and polymers are used to create PICs with certain unique properties. Hybrid integration can combine multiple material platforms via optical coupling and realize multi-functional PICs that overcome the limitations of a single material platform. This allows for a broad application base for hybrid integrated PICs, greatly enhancing their usability and practicality. In this paper, we will discuss the methodology and applications of hybrid integration for chip-scale laser systems, including narrow linewidth, widely tunable external cavity lasers, laser beam combining, integrated frequency combs, and integrated Pockels lasers.
{"title":"Hybrid integrated chip-scale laser systems","authors":"C. Porter, S. Zeng, X. Zhao, L. Zhu","doi":"10.1063/5.0159527","DOIUrl":"https://doi.org/10.1063/5.0159527","url":null,"abstract":"Photonic integrated circuits (PICs) allow for the rapid advancement of a wide range of optical devices on a compact platform, making them more useful and readily available in the commercial market. Various materials such as III–V semiconductors, silicon, silicon nitride, lithium niobate, and polymers are used to create PICs with certain unique properties. Hybrid integration can combine multiple material platforms via optical coupling and realize multi-functional PICs that overcome the limitations of a single material platform. This allows for a broad application base for hybrid integrated PICs, greatly enhancing their usability and practicality. In this paper, we will discuss the methodology and applications of hybrid integration for chip-scale laser systems, including narrow linewidth, widely tunable external cavity lasers, laser beam combining, integrated frequency combs, and integrated Pockels lasers.","PeriodicalId":8198,"journal":{"name":"APL Photonics","volume":" ","pages":""},"PeriodicalIF":5.6,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"44112309","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Duo Jin, Zhen-xu Bai, Yifu Chen, Wenqiang Fan, Yulei Wang, Z. Lü, R. Mildren
The cascade operation of Brillouin lasers (BLs) is an identified obstacle to single-frequency power scaling and further compression of the fundamental linewidth. In this study, we reveal the relationship between the maximum cascade order and system parameters, starting from the phase-matching conditions of the Stokes cascade. The second Stokes is suppressed for modes that fall away the Brillouin gain linewidth (ΓB), which is heightened for Brillouin gain media with high sound velocity, large refractive index, and narrow linewidth. Diamond, with its extremely high product of speed of sound and refractive index, satisfies these requirements and is found to achieve cascade-free intramode scattering (TEM00) without manipulating cavity mode structures. This study elucidates a route to single-frequency, narrow-linewidth BLs via Brillouin material selection.
{"title":"Intrinsic cascade-free intramode scattering Brillouin laser","authors":"Duo Jin, Zhen-xu Bai, Yifu Chen, Wenqiang Fan, Yulei Wang, Z. Lü, R. Mildren","doi":"10.1063/5.0155283","DOIUrl":"https://doi.org/10.1063/5.0155283","url":null,"abstract":"The cascade operation of Brillouin lasers (BLs) is an identified obstacle to single-frequency power scaling and further compression of the fundamental linewidth. In this study, we reveal the relationship between the maximum cascade order and system parameters, starting from the phase-matching conditions of the Stokes cascade. The second Stokes is suppressed for modes that fall away the Brillouin gain linewidth (ΓB), which is heightened for Brillouin gain media with high sound velocity, large refractive index, and narrow linewidth. Diamond, with its extremely high product of speed of sound and refractive index, satisfies these requirements and is found to achieve cascade-free intramode scattering (TEM00) without manipulating cavity mode structures. This study elucidates a route to single-frequency, narrow-linewidth BLs via Brillouin material selection.","PeriodicalId":8198,"journal":{"name":"APL Photonics","volume":" ","pages":""},"PeriodicalIF":5.6,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41852159","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Müller, A. Bablich, R. Bornemann, Nils Marrenbach, Paul Kienitz, P. Haring Bolívar
In this work, a promising device for direct optical envelope mixing, the Intrinsic Photomixing Detector (IPD) based on hydrogenated amorphous silicon, is reported. The IPD directly generates a photocurrent proportional to the nonlinear mixing of two optical modulation envelope functions. Experiments illustrate efficient mixing in the visible range at low light levels down to ϕ1 = 4.36 mW/cm2 (444 nm) and ϕ2 = 1.03 mW/cm2 (636 nm). Modulation frequencies exceeding the MHz range are demonstrated. Electro-optical simulations identify defect-induced electrical field screening within the absorber to cause the nonlinear mixing process, opening-up the opportunity to tailor devices toward application-specific requirements. The IPD functionality paves the way toward very simple but high-performance photodetectors for 3D imaging and ranging for direct optical convolutional sensors or for efficient optical logic gates. Using amorphous silicon provides a photodetector material base, which can easily be integrated on top of silicon electronics, enabling fill factors of up to 100%.
{"title":"Intrinsic photomixing detector based on amorphous silicon for envelope mixing of optical signals","authors":"M. Müller, A. Bablich, R. Bornemann, Nils Marrenbach, Paul Kienitz, P. Haring Bolívar","doi":"10.1063/5.0149024","DOIUrl":"https://doi.org/10.1063/5.0149024","url":null,"abstract":"In this work, a promising device for direct optical envelope mixing, the Intrinsic Photomixing Detector (IPD) based on hydrogenated amorphous silicon, is reported. The IPD directly generates a photocurrent proportional to the nonlinear mixing of two optical modulation envelope functions. Experiments illustrate efficient mixing in the visible range at low light levels down to ϕ1 = 4.36 mW/cm2 (444 nm) and ϕ2 = 1.03 mW/cm2 (636 nm). Modulation frequencies exceeding the MHz range are demonstrated. Electro-optical simulations identify defect-induced electrical field screening within the absorber to cause the nonlinear mixing process, opening-up the opportunity to tailor devices toward application-specific requirements. The IPD functionality paves the way toward very simple but high-performance photodetectors for 3D imaging and ranging for direct optical convolutional sensors or for efficient optical logic gates. Using amorphous silicon provides a photodetector material base, which can easily be integrated on top of silicon electronics, enabling fill factors of up to 100%.","PeriodicalId":8198,"journal":{"name":"APL Photonics","volume":" ","pages":""},"PeriodicalIF":5.6,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47452001","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Photonic integrated circuits have benefited many fields in the natural sciences. Their nanoscale patterning has led to the discovery of novel sources and detectors from ultraviolet to microwaves. Yet terahertz technologies have so far leveraged surprisingly little of the design and material freedom provided by photonic integrated circuits. Despite photoconduction—the process in which light is absorbed above the bandgap of a semiconductor to generate free carriers—and nonlinear up- and down-conversion being by far the two most widespread approaches to generate and detect terahertz waves, so far, terahertz technologies have been mostly employed in bulk. In this perspective, we discuss the current state-of-the-art, challenges, and perspectives for hybrid optical-terahertz photonic chips. We focus, in particular, on χ(2) and χ(3) nonlinear waveguides and waveguide-integrated photoconductive devices. We highlight opportunities in the micro- and macroscale design of waveguide geometries and printed antennas for the optimization of emission and detection efficiencies of terahertz waves. Realizing complex functionalities for terahertz photonics on a single chip may come into reach by integration and miniaturization compatible with telecom and fiber technologies.
{"title":"Present and future of terahertz integrated photonic devices","authors":"S. Rajabali, Ileana-Cristina Benea-Chelmus","doi":"10.1063/5.0146912","DOIUrl":"https://doi.org/10.1063/5.0146912","url":null,"abstract":"Photonic integrated circuits have benefited many fields in the natural sciences. Their nanoscale patterning has led to the discovery of novel sources and detectors from ultraviolet to microwaves. Yet terahertz technologies have so far leveraged surprisingly little of the design and material freedom provided by photonic integrated circuits. Despite photoconduction—the process in which light is absorbed above the bandgap of a semiconductor to generate free carriers—and nonlinear up- and down-conversion being by far the two most widespread approaches to generate and detect terahertz waves, so far, terahertz technologies have been mostly employed in bulk. In this perspective, we discuss the current state-of-the-art, challenges, and perspectives for hybrid optical-terahertz photonic chips. We focus, in particular, on χ(2) and χ(3) nonlinear waveguides and waveguide-integrated photoconductive devices. We highlight opportunities in the micro- and macroscale design of waveguide geometries and printed antennas for the optimization of emission and detection efficiencies of terahertz waves. Realizing complex functionalities for terahertz photonics on a single chip may come into reach by integration and miniaturization compatible with telecom and fiber technologies.","PeriodicalId":8198,"journal":{"name":"APL Photonics","volume":" ","pages":""},"PeriodicalIF":5.6,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"45908111","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Cáceres-Aravena, B. Real, Diego Guzmán-Silva, Paloma Vildoso, I. Salinas, A. Amo, T. Ozawa, R. Vicencio
The transfer of information between topological edge states is a robust way of spatially manipulating spatial states in lattice environments. This method is particularly efficient when the edge modes are kept within the topological gap of the lattice during the transfer. In this work, we show experimentally the transfer of photonic modes between topological edge states located at opposite ends of a dimerized one-dimensional photonic lattice. We use a diamond lattice of coupled waveguides and show that the topological transfer is insensitive to the presence of a high density of states in the form of a flat band at an energy close to that of the edge states and prevails in the presence of a hopping impurity. We explore the dynamics in the waveguide lattice using a wavelength-scan method, where different input wavelengths translate into different effective lattice lengths. Our results offer an alternative way to the implementation of efficient transfer protocols based on active driving mechanisms.
{"title":"Edge-to-edge topological spectral transfer in diamond photonic lattices","authors":"G. Cáceres-Aravena, B. Real, Diego Guzmán-Silva, Paloma Vildoso, I. Salinas, A. Amo, T. Ozawa, R. Vicencio","doi":"10.1063/5.0153770","DOIUrl":"https://doi.org/10.1063/5.0153770","url":null,"abstract":"The transfer of information between topological edge states is a robust way of spatially manipulating spatial states in lattice environments. This method is particularly efficient when the edge modes are kept within the topological gap of the lattice during the transfer. In this work, we show experimentally the transfer of photonic modes between topological edge states located at opposite ends of a dimerized one-dimensional photonic lattice. We use a diamond lattice of coupled waveguides and show that the topological transfer is insensitive to the presence of a high density of states in the form of a flat band at an energy close to that of the edge states and prevails in the presence of a hopping impurity. We explore the dynamics in the waveguide lattice using a wavelength-scan method, where different input wavelengths translate into different effective lattice lengths. Our results offer an alternative way to the implementation of efficient transfer protocols based on active driving mechanisms.","PeriodicalId":8198,"journal":{"name":"APL Photonics","volume":" ","pages":""},"PeriodicalIF":5.6,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41332287","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A comprehensive theoretical framework for the inverse design of correlation induced effects with optical beams is introduced. Correlation induced effects are able to modify the intensity distribution of an optical beam drastically via effects such as correlation induced splitting, focusing, and shifting. The inverse design steps are given analytically, which allows the analysis of several related experiments. Finally, an algorithm for more complex numerical inverse design is overviewed and demonstrated.
{"title":"Inverse design of optical correlation induced effects","authors":"M. Luo, M. Ornigotti, M. Koivurova","doi":"10.1063/5.0144616","DOIUrl":"https://doi.org/10.1063/5.0144616","url":null,"abstract":"A comprehensive theoretical framework for the inverse design of correlation induced effects with optical beams is introduced. Correlation induced effects are able to modify the intensity distribution of an optical beam drastically via effects such as correlation induced splitting, focusing, and shifting. The inverse design steps are given analytically, which allows the analysis of several related experiments. Finally, an algorithm for more complex numerical inverse design is overviewed and demonstrated.","PeriodicalId":8198,"journal":{"name":"APL Photonics","volume":" ","pages":""},"PeriodicalIF":5.6,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48776066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Non-contact ultrasound excitation based on the photoacoustic effect using short optical pulses has been widely used for biomedical and industrial inspections. However, generating and detecting photoacoustic signals in water or aqueous samples requires careful choice of the excitation wavelength. Here, we show that continuous-wave (CW) ultrasound can be directly generated in aqueous samples by irradiating them with the CW sub-terahertz waves modulated at acoustic frequencies, even when the stress confinement condition is not satisfied. The ultrasound generated at resonance can be detected even in the air using a microphone. The sub-terahertz waves exhibit a water absorption coefficient akin to peak near-infrared wavelengths while offering transmittance through diverse materials. Leveraging recent advances in high-frequency electronics, we develop a compact experimental system with the potential for further miniaturization. To demonstrate the potential of the proposed method, we present proof-of-concept applications of bulk modulus measurement of gelatin gels and in vivo anatomical imaging of human hands.
{"title":"Generating in vivo continuous ultrasound based on sub-terahertz photoacoustic effect","authors":"Natsumi Ichikawa, Y. Monnai","doi":"10.1063/5.0157652","DOIUrl":"https://doi.org/10.1063/5.0157652","url":null,"abstract":"Non-contact ultrasound excitation based on the photoacoustic effect using short optical pulses has been widely used for biomedical and industrial inspections. However, generating and detecting photoacoustic signals in water or aqueous samples requires careful choice of the excitation wavelength. Here, we show that continuous-wave (CW) ultrasound can be directly generated in aqueous samples by irradiating them with the CW sub-terahertz waves modulated at acoustic frequencies, even when the stress confinement condition is not satisfied. The ultrasound generated at resonance can be detected even in the air using a microphone. The sub-terahertz waves exhibit a water absorption coefficient akin to peak near-infrared wavelengths while offering transmittance through diverse materials. Leveraging recent advances in high-frequency electronics, we develop a compact experimental system with the potential for further miniaturization. To demonstrate the potential of the proposed method, we present proof-of-concept applications of bulk modulus measurement of gelatin gels and in vivo anatomical imaging of human hands.","PeriodicalId":8198,"journal":{"name":"APL Photonics","volume":" ","pages":""},"PeriodicalIF":5.6,"publicationDate":"2023-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"46190415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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