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Research Articles|181 Article(s)
Research Articles
Exploring uncharted multiband hyperbolic dispersion in conjugated polymers: a first-principles study
Suim Lim, Dong Hee Park, Bin Chan Joo, Yeon Ui Lee, and Kanghoon Yim
Hyperbolic materials are highly anisotropic optical media that provide valuable assistance in emission engineering, nanoscale light focusing, and scattering enhancement. Recently discovered organic hyperbolic materials (OHMs) with exceptional biocompatibility and tunability offer promising prospects as next-generation optical media for nanoscopy, enabling superresolution bioimaging capabilities. Nonetheless, an OHM is still less accessible to many researchers because of its rarity and narrow operating wavelength range. Here, we employ first-principles calculations to expand the number of known OHMs, including conjugated polymers with multiple assembly units. Through the systematic investigation of structural and optical properties of the target copolymers, we discover extraordinary multiband hyperbolic dispersions from candidate OHMs. This approach provides a new perspective on the molecular-scale design of broadband, low-loss OHMs. It aids in identifying potential hyperbolic material candidates applicable to optical engineering and super-resolution bioimaging, offering new insights into nanoscale light–matter interactions. Hyperbolic materials are highly anisotropic optical media that provide valuable assistance in emission engineering, nanoscale light focusing, and scattering enhancement. Recently discovered organic hyperbolic materials (OHMs) with exceptional biocompatibility and tunability offer promising prospects as next-generation optical media for nanoscopy, enabling superresolution bioimaging capabilities. Nonetheless, an OHM is still less accessible to many researchers because of its rarity and narrow operating wavelength range. Here, we employ first-principles calculations to expand the number of known OHMs, including conjugated polymers with multiple assembly units. Through the systematic investigation of structural and optical properties of the target copolymers, we discover extraordinary multiband hyperbolic dispersions from candidate OHMs. This approach provides a new perspective on the molecular-scale design of broadband, low-loss OHMs. It aids in identifying potential hyperbolic material candidates applicable to optical engineering and super-resolution bioimaging, offering new insights into nanoscale light–matter interactions.
Advanced Photonics
- Publication Date: Mar. 13, 2025
- Vol. 7, Issue 3, 036001 (2025)
Metasurface-enabled quantum holograms with hybrid entanglement
Hong Liang, Wai Chun Wong, Tailin An, and Jensen Li
Metasurfaces, with their capability to control all possible dimensions of light, have become integral to quantum optical applications, including quantum state generation, operation, and tomography. We utilize a metasurface to generate polarization–hologram hybrid entanglement between a signal–idler photon pair to construct a quantum hologram. The properties of the quantum hologram can be revealed by collapsing the polarization degree of freedom of the idler photon, inducing interference between two holographic states of the signal photon as a meaningful and selective erasure of the holographic content. On the contrary, interference disappears when the idler photon is detected without observing polarization. This process can be further interpreted as a quantum holographic eraser, where the erasing action is visualized with erased contents in holograms. Our construction of a polarization–hologram hybrid entangled state with metasurfaces will be useful for quantum communication with enhanced robustness, anticounterfeiting applications through the additional quantum degrees of freedom or phase difference between two holographic states, and as an emerging platform for exploring fundamental quantum concepts for entanglement and nonlocality. Metasurfaces, with their capability to control all possible dimensions of light, have become integral to quantum optical applications, including quantum state generation, operation, and tomography. We utilize a metasurface to generate polarization–hologram hybrid entanglement between a signal–idler photon pair to construct a quantum hologram. The properties of the quantum hologram can be revealed by collapsing the polarization degree of freedom of the idler photon, inducing interference between two holographic states of the signal photon as a meaningful and selective erasure of the holographic content. On the contrary, interference disappears when the idler photon is detected without observing polarization. This process can be further interpreted as a quantum holographic eraser, where the erasing action is visualized with erased contents in holograms. Our construction of a polarization–hologram hybrid entangled state with metasurfaces will be useful for quantum communication with enhanced robustness, anticounterfeiting applications through the additional quantum degrees of freedom or phase difference between two holographic states, and as an emerging platform for exploring fundamental quantum concepts for entanglement and nonlocality.
Advanced Photonics
- Publication Date: Mar. 11, 2025
- Vol. 7, Issue 2, 026006 (2025)
Cascaded adaptive aberration-eliminating multimode fiber imaging
Zhong Wen, Qilin Deng, Quanzhi Li, Yizhou Tan... and Qing Yang|Show fewer author(s)
In vivo microscopic imaging inside a biological lumen such as the gastrointestinal tract, respiratory airways, or within blood vessels has faced significant technological challenges for decades. A promising candidate technology is the multimode fiber (MMF) endoscope, which enables minimally invasive diagnostics at a resolution reaching the cellular level. However, for in vivo imaging applications deep inside a biological lumen, sample-induced aberrations and the dynamic dispersion in the MMF make the MMF endoscope a chaotic system with many unknowns, where multiple minor fluctuations can couple and compound into intractable problems. We introduce a dynamically encoding, cascaded, optical, and ultrathin polychromatic light-field endoscopy (DECOUPLE) to tackle this challenge. DECOUPLE includes an adaptive aberration correction that can accurately track and control MMF behavior in the spatial-frequency domain to compensate for chaos introduced during complex dynamic imaging processes. We demonstrate the flexibility and practicality of DECOUPLE for noninvasive volumetric imaging in two colors for light passing through various highly aberrating samples including 120-μm-thick onion epidermal slices and 80-μm-thick layers of fat emulsions. To summarize, we represent a significant step toward practical in vivo imaging deep within biological tissue. In vivo microscopic imaging inside a biological lumen such as the gastrointestinal tract, respiratory airways, or within blood vessels has faced significant technological challenges for decades. A promising candidate technology is the multimode fiber (MMF) endoscope, which enables minimally invasive diagnostics at a resolution reaching the cellular level. However, for in vivo imaging applications deep inside a biological lumen, sample-induced aberrations and the dynamic dispersion in the MMF make the MMF endoscope a chaotic system with many unknowns, where multiple minor fluctuations can couple and compound into intractable problems. We introduce a dynamically encoding, cascaded, optical, and ultrathin polychromatic light-field endoscopy (DECOUPLE) to tackle this challenge. DECOUPLE includes an adaptive aberration correction that can accurately track and control MMF behavior in the spatial-frequency domain to compensate for chaos introduced during complex dynamic imaging processes. We demonstrate the flexibility and practicality of DECOUPLE for noninvasive volumetric imaging in two colors for light passing through various highly aberrating samples including 120-μm-thick onion epidermal slices and 80-μm-thick layers of fat emulsions. To summarize, we represent a significant step toward practical in vivo imaging deep within biological tissue.
Advanced Photonics
- Publication Date: Mar. 08, 2025
- Vol. 7, Issue 2, 026005 (2025)
Single-shot spatial-temporal-spectral complex amplitude imaging via wavelength-time multiplexing
Yingming Xu, Chengzhi Jin, Liangze Pan, Yu He... and Jianqiang Zhu|Show fewer author(s)
Single-shot ultrafast multidimensional optical imaging (UMOI) combines ultrahigh temporal resolution with multidimensional imaging capabilities in a snapshot, making it an essential tool for real-time detection and analysis of ultrafast scenes. However, current single-shot UMOI techniques cannot simultaneously capture the spatial-temporal-spectral complex amplitude information, hampering it from complete analyses of ultrafast scenes. To address this issue, we propose a single-shot spatial-temporal-spectral complex amplitude imaging (STS-CAI) technique using wavelength and time multiplexing. By employing precise modulation of a broadband pulse via an encoding plate in coherent diffraction imaging and spatial-temporal shearing through a wide-open-slit streak camera, dual-mode multiplexing image reconstruction of wavelength and time is achieved, which significantly enhances the efficiency of information acquisition. Experimentally, a custom-built STS-CAI apparatus precisely measures the spatiotemporal characteristics of picosecond spatiotemporally chirped and spatial vortex pulses, respectively. STS-CAI demonstrates both ultrahigh temporal resolution and robust phase sensitivity. Prospectively, this technique is valuable for spatiotemporal coupling measurements of large-aperture ultrashort pulses and offers promising applications in both fundamental research and applied sciences. Single-shot ultrafast multidimensional optical imaging (UMOI) combines ultrahigh temporal resolution with multidimensional imaging capabilities in a snapshot, making it an essential tool for real-time detection and analysis of ultrafast scenes. However, current single-shot UMOI techniques cannot simultaneously capture the spatial-temporal-spectral complex amplitude information, hampering it from complete analyses of ultrafast scenes. To address this issue, we propose a single-shot spatial-temporal-spectral complex amplitude imaging (STS-CAI) technique using wavelength and time multiplexing. By employing precise modulation of a broadband pulse via an encoding plate in coherent diffraction imaging and spatial-temporal shearing through a wide-open-slit streak camera, dual-mode multiplexing image reconstruction of wavelength and time is achieved, which significantly enhances the efficiency of information acquisition. Experimentally, a custom-built STS-CAI apparatus precisely measures the spatiotemporal characteristics of picosecond spatiotemporally chirped and spatial vortex pulses, respectively. STS-CAI demonstrates both ultrahigh temporal resolution and robust phase sensitivity. Prospectively, this technique is valuable for spatiotemporal coupling measurements of large-aperture ultrashort pulses and offers promising applications in both fundamental research and applied sciences.
Advanced Photonics
- Publication Date: Mar. 07, 2025
- Vol. 7, Issue 2, 026004 (2025)
3D-printed micro-axicon enables extended depth-of-focus intravascular optical coherence tomography in vivo
Pavel Ruchka, Alok Kushwaha, Jessica A. Marathe, Lei Xiang... and Jiawen Li|Show fewer author(s)
A fundamental challenge in endoscopy is how to fabricate a small fiber-optic probe that can achieve comparable function to devices with large, complicated optics. To achieve high resolution over an extended depth of focus (DOF), the application of needle-like beams has been proposed. However, existing methods for miniaturized needle-beam designs fail to adequately correct astigmatism and other monochromatic aberrations, limiting the resolution of at least one axis. Here, we describe an approach to realize freeform beam-shaping endoscopic probes via two-photon polymerization three-dimensional (3D) printing. We present a design achieving <8μm lateral resolution with a DOF of ∼800 μm. The probe has a diameter of <260 μm (without the torque coil and catheters) and is fabricated using a single printing step directly on the optical fiber. The probe was successfully utilized for intravascular imaging in living diabetic swine at multiple time points, as well as human atherosclerotic plaques ex vivo. To the best of our knowledge, this is the first report of a 3D-printed micro-optic for in vivo imaging of the coronary arteries. These results are a substantial step to enable the clinical adoption of both 3D-printed micro-optics and beam-tailoring devices. A fundamental challenge in endoscopy is how to fabricate a small fiber-optic probe that can achieve comparable function to devices with large, complicated optics. To achieve high resolution over an extended depth of focus (DOF), the application of needle-like beams has been proposed. However, existing methods for miniaturized needle-beam designs fail to adequately correct astigmatism and other monochromatic aberrations, limiting the resolution of at least one axis. Here, we describe an approach to realize freeform beam-shaping endoscopic probes via two-photon polymerization three-dimensional (3D) printing. We present a design achieving <8μm lateral resolution with a DOF of ∼800 μm. The probe has a diameter of <260 μm (without the torque coil and catheters) and is fabricated using a single printing step directly on the optical fiber. The probe was successfully utilized for intravascular imaging in living diabetic swine at multiple time points, as well as human atherosclerotic plaques ex vivo. To the best of our knowledge, this is the first report of a 3D-printed micro-optic for in vivo imaging of the coronary arteries. These results are a substantial step to enable the clinical adoption of both 3D-printed micro-optics and beam-tailoring devices.
Advanced Photonics
- Publication Date: Mar. 03, 2025
- Vol. 7, Issue 2, 026003 (2025)
Attosecond time-resolved measurements of electron and photon beams with a variable polarization X-band radiofrequency deflector at an X-ray free-electron laser
Eduard Prat, Zheqiao Geng, Christoph Kittel, Alexander Malyzhenkov... and Paolo Craievich|Show fewer author(s)
X-ray free-electron lasers (FELs) are cutting-edge research instruments employed in multiple scientific fields capable of analyzing matter with unprecedented time and spatial resolutions. Time-resolved measurements of electron and photon beams are essential in X-ray FELs. Radiofrequency (RF) transverse deflecting structures (TDSs) with a fixed streaking direction are standard diagnostics to measure the temporal properties of the electron beams. If placed after the undulator of the FEL facility, TDSs can also be employed to reconstruct the power profile of the FEL pulses. We present measurements of an X-band RF TDS system with variable polarization with a resolution below one femtosecond. We show FEL power profile measurements with associated root mean square pulse durations as short as 300 attoseconds. The measurements have been carried out at Athos, the soft X-ray beamline of SwissFEL. Measurements with variable polarization and attosecond resolution are essential to characterize and optimize the electron beams in all its dimensions for all types of X-ray FEL experiments, in particular for ultrafast X-ray applications. X-ray free-electron lasers (FELs) are cutting-edge research instruments employed in multiple scientific fields capable of analyzing matter with unprecedented time and spatial resolutions. Time-resolved measurements of electron and photon beams are essential in X-ray FELs. Radiofrequency (RF) transverse deflecting structures (TDSs) with a fixed streaking direction are standard diagnostics to measure the temporal properties of the electron beams. If placed after the undulator of the FEL facility, TDSs can also be employed to reconstruct the power profile of the FEL pulses. We present measurements of an X-band RF TDS system with variable polarization with a resolution below one femtosecond. We show FEL power profile measurements with associated root mean square pulse durations as short as 300 attoseconds. The measurements have been carried out at Athos, the soft X-ray beamline of SwissFEL. Measurements with variable polarization and attosecond resolution are essential to characterize and optimize the electron beams in all its dimensions for all types of X-ray FEL experiments, in particular for ultrafast X-ray applications.
Advanced Photonics
- Publication Date: Feb. 27, 2025
- Vol. 7, Issue 2, 026002 (2025)
Single-shot volumetric fluorescence imaging with neural fields
Oumeng Zhang, Haowen Zhou, Brandon Y. Feng, Elin M. Larsson... and Changhuei Yang|Show fewer author(s)
Single-shot volumetric fluorescence (SVF) imaging offers a significant advantage over traditional imaging methods that require scanning across multiple axial planes, as it can capture biological processes with high temporal resolution. The key challenges in SVF imaging include requiring sparsity constraints, eliminating depth ambiguity in the reconstruction, and maintaining high resolution across a large field of view. We introduce the QuadraPol point spread function (PSF) combined with neural fields, an approach for SVF imaging. This method utilizes a custom polarizer at the back focal plane and a polarization camera to detect fluorescence, effectively encoding the three-dimensional scene within a compact PSF without depth ambiguity. In addition, we propose a reconstruction algorithm based on the neural field technique that provides improved reconstruction quality compared with classical deconvolution methods. QuadraPol PSF, combined with neural fields, significantly reduces the acquisition time of a conventional fluorescence microscope by ∼20 times and captures a 100-mm3 cubic volume in one shot. We validate the effectiveness of both our hardware and algorithm through all-in-focus imaging of bacterial colonies on sand surfaces and visualization of plant root morphology. Our approach offers a powerful tool for advancing biological research and ecological studies. Single-shot volumetric fluorescence (SVF) imaging offers a significant advantage over traditional imaging methods that require scanning across multiple axial planes, as it can capture biological processes with high temporal resolution. The key challenges in SVF imaging include requiring sparsity constraints, eliminating depth ambiguity in the reconstruction, and maintaining high resolution across a large field of view. We introduce the QuadraPol point spread function (PSF) combined with neural fields, an approach for SVF imaging. This method utilizes a custom polarizer at the back focal plane and a polarization camera to detect fluorescence, effectively encoding the three-dimensional scene within a compact PSF without depth ambiguity. In addition, we propose a reconstruction algorithm based on the neural field technique that provides improved reconstruction quality compared with classical deconvolution methods. QuadraPol PSF, combined with neural fields, significantly reduces the acquisition time of a conventional fluorescence microscope by ∼20 times and captures a 100-mm3 cubic volume in one shot. We validate the effectiveness of both our hardware and algorithm through all-in-focus imaging of bacterial colonies on sand surfaces and visualization of plant root morphology. Our approach offers a powerful tool for advancing biological research and ecological studies.
Advanced Photonics
- Publication Date: Feb. 25, 2025
- Vol. 7, Issue 2, 026001 (2025)
Skyrmionic spin textures in nonparaxial light
Xinrui Lei, Aiping Yang, Xusheng Chen, Luping Du... and Xiaocong Yuan|Show fewer author(s)
Topological textures in optics such as skyrmions and merons are increasingly studied for their potential functions in light–matter interactions, deep-subwavelength imaging, and nanometrology. However, they were previously generated either in strongly confined guided waves or in paraxial beams. This has posed a significant challenge in constructing skyrmions in nonparaxial propagating waves due to the lack of symmetry-breaking in the optical field and difficulty in characterizing the full three-dimensional spin textures at the nanoscale. We theoretically propose and experimentally demonstrate the generation of skyrmionic spin textures in nonparaxial light, where skyrmionic textures with a Bloch-type scheme, including isolated skyrmioniums, skyrmion, and meron lattices are generated in free space. We introduce the interplay between the Hertz potentials to break the dual symmetry of light and build well-defined domains of skyrmions. We experimentally realized the topological textures by applying a hybrid polarized optical vortex and observed the complete three-dimensional spin distributions by a dual-mode waveguide probe. By bridging the gap in the skyrmionic group, we present a topologic diagram, showing how spin–orbit coupling of light governs the spin topology. These findings offer new insights into optical quasi-particles and electron–photon correspondence, potentially facilitating advanced applications in optical metrology, sensing, and storage. Topological textures in optics such as skyrmions and merons are increasingly studied for their potential functions in light–matter interactions, deep-subwavelength imaging, and nanometrology. However, they were previously generated either in strongly confined guided waves or in paraxial beams. This has posed a significant challenge in constructing skyrmions in nonparaxial propagating waves due to the lack of symmetry-breaking in the optical field and difficulty in characterizing the full three-dimensional spin textures at the nanoscale. We theoretically propose and experimentally demonstrate the generation of skyrmionic spin textures in nonparaxial light, where skyrmionic textures with a Bloch-type scheme, including isolated skyrmioniums, skyrmion, and meron lattices are generated in free space. We introduce the interplay between the Hertz potentials to break the dual symmetry of light and build well-defined domains of skyrmions. We experimentally realized the topological textures by applying a hybrid polarized optical vortex and observed the complete three-dimensional spin distributions by a dual-mode waveguide probe. By bridging the gap in the skyrmionic group, we present a topologic diagram, showing how spin–orbit coupling of light governs the spin topology. These findings offer new insights into optical quasi-particles and electron–photon correspondence, potentially facilitating advanced applications in optical metrology, sensing, and storage.
Advanced Photonics
- Publication Date: Feb. 14, 2025
- Vol. 7, Issue 1, 016009 (2025)
Wavelength-insensitive snapshot Stokes polarimetric imaging based on cascaded metasurfaces
Xuanguang Wu, Kai Pan, Xuanyu Wu, Xinhao Fan... and Jianlin Zhao|Show fewer author(s)
Compact, single-shot, and accurate Stokes polarimetric imagers are highly desirable for imaging at all scales, from remote sensing to biological diagnosis. Recently, polarimetric imaging demonstrated on the metasurface platform is accelerating its realization and revolutionizing associated techniques and imagers. These breakthroughs, however, are greatly limited by the single operating wavelength and the complexity of metasurfaces. We present a minimalist yet powerful cascaded metasurface strategy to realize wavelength-insensitive snapshot Stokes polarimetric imaging. Two cascaded metasurface polarization gratings built into the 4f imaging system enable optical spin Hall momentum shifts and cross-polarization interference of incident light, which are wavelength-robust and free of polarization cross talk, allowing the 4f system to perform accurate and single-shot polarimetric imaging at an arbitrary wavelength and even low-coherence light. We demonstrate the feasibility and robustness of this cascaded metasurface architecture by characterizing diverse polarization objects. We open an avenue for polarimetric imaging and exhibit promising potential in emerging areas of applications such as biological diagnosis. Compact, single-shot, and accurate Stokes polarimetric imagers are highly desirable for imaging at all scales, from remote sensing to biological diagnosis. Recently, polarimetric imaging demonstrated on the metasurface platform is accelerating its realization and revolutionizing associated techniques and imagers. These breakthroughs, however, are greatly limited by the single operating wavelength and the complexity of metasurfaces. We present a minimalist yet powerful cascaded metasurface strategy to realize wavelength-insensitive snapshot Stokes polarimetric imaging. Two cascaded metasurface polarization gratings built into the 4f imaging system enable optical spin Hall momentum shifts and cross-polarization interference of incident light, which are wavelength-robust and free of polarization cross talk, allowing the 4f system to perform accurate and single-shot polarimetric imaging at an arbitrary wavelength and even low-coherence light. We demonstrate the feasibility and robustness of this cascaded metasurface architecture by characterizing diverse polarization objects. We open an avenue for polarimetric imaging and exhibit promising potential in emerging areas of applications such as biological diagnosis.
Advanced Photonics
- Publication Date: Feb. 12, 2025
- Vol. 7, Issue 1, 016008 (2025)
Microcomb-driven photonic chip for solving partial differential equations
Hongyi Yuan, Zhuochen Du, Huixin Qi, Guoxiang Si... and Qihuang Gong|Show fewer author(s)
With the development of the big data era, the need for computation power is dramatically growing, especially for solving partial differential equations (PDEs), because PDEs are often used to describe complex systems and phenomena in both science and engineering. However, it is still a great challenge for on-chip photonic solving of time-evolving PDEs because of the difficulties in big coefficient matrix photonic computing, high accuracy, and error accumulation. We overcome these challenges by realizing a microcomb-driven photonic chip and introducing time-division multiplexing and matrix partition techniques into PDE photonic solving, which can solve PDEs with a large coefficient matrix on a photonic chip with a limited size. Time-evolving PDEs, including the heat equation with the first order of time derivative, the wave equation with the second order of time derivative, and the nonlinear Burgers equation, are solved with an accuracy of up to 97%. Furthermore, the parallel solving of the Poisson equation and Laplace’s equation is demonstrated experimentally on a single chip, with an accuracy of 95.9% and 95.8%, respectively. We offer a powerful photonic platform for solving PDEs, which takes a step forward in the application of photonic chips in mathematical problems and will promote the development of on-chip photonic computing. With the development of the big data era, the need for computation power is dramatically growing, especially for solving partial differential equations (PDEs), because PDEs are often used to describe complex systems and phenomena in both science and engineering. However, it is still a great challenge for on-chip photonic solving of time-evolving PDEs because of the difficulties in big coefficient matrix photonic computing, high accuracy, and error accumulation. We overcome these challenges by realizing a microcomb-driven photonic chip and introducing time-division multiplexing and matrix partition techniques into PDE photonic solving, which can solve PDEs with a large coefficient matrix on a photonic chip with a limited size. Time-evolving PDEs, including the heat equation with the first order of time derivative, the wave equation with the second order of time derivative, and the nonlinear Burgers equation, are solved with an accuracy of up to 97%. Furthermore, the parallel solving of the Poisson equation and Laplace’s equation is demonstrated experimentally on a single chip, with an accuracy of 95.9% and 95.8%, respectively. We offer a powerful photonic platform for solving PDEs, which takes a step forward in the application of photonic chips in mathematical problems and will promote the development of on-chip photonic computing.
Advanced Photonics
- Publication Date: Feb. 14, 2025
- Vol. 7, Issue 1, 016007 (2025)
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