Contents
2025
Volume: 7 Issue 4
11 Article(s)
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News and Commentaries
Robust future in chiral sensing
Kimani C. Toussaint, and Yihang Fan
The authors comment on a recent significant advancement in developing a chiral sensor that is both sensitive and robust.The authors comment on a recent significant advancement in developing a chiral sensor that is both sensitive and robust..
Advanced Photonics
- Publication Date: May. 23, 2025
- Vol. 7, Issue 4, 040501 (2025)
Reviews
Optical vortices in communication systems: mode (de)modulation, processing, and transmission
Shuqing Chen, Jiafu Chen, Tian Xia, Zhenwei Xie... and Xiaocong Yuan|Show fewer author(s)
Optical vortices, characterized by their infinite orthogonal eigenmodes—such as orbital angular momentum (OAM) and cylindrical vector...show moreOptical vortices, characterized by their infinite orthogonal eigenmodes—such as orbital angular momentum (OAM) and cylindrical vector beam (CVB) modes—offer unprecedented opportunities for advancing optical communication systems. The core components of these systems—mode (de)modulation, mode processing, and mode transmission—are fundamental to the construction and networking of OAM/CVB mode-based communication networks. They significantly influence signal encoding, enhance channel capacity, and facilitate signal interconnection and transmission. We explore the historical development and recent advancements in optical vortex-based communication systems from these three critical perspectives. We systematically summarize the normative definitions and research progress related to key concepts such as mode multiplexing and routing. We also demonstrate the performance of these systems in terms of communication capacity, bit error rate, and more. Furthermore, we examine the substantial challenges and future prospects in this field, with the aim of offering cutting-edge insights that will facilitate the advancement and practical implementation of optical communication networks leveraging optical vortex modes..
Advanced Photonics
- Publication Date: May. 19, 2025
- Vol. 7, Issue 4, 044001 (2025)
Research Articles
Spin Hamiltonian in the modulated momenta of light
Juan Feng, Zengya Li, Luqi Yuan, Erez Hasman... and Xianfeng Chen|Show fewer author(s)
Spatial photonic Ising machines (SPIMs) are promising computation devices that can be used to find the ground states of different spin...show moreSpatial photonic Ising machines (SPIMs) are promising computation devices that can be used to find the ground states of different spin Hamiltonians and solve large-scale optimization problems. The photonic architecture leverages the matrix multiplexing ability of light to accelerate the computing of spin Hamiltonian via free space light transform. However, the intrinsic long-range nature of spatial light only allows for uncontrolled all-to-all spin interaction. We explore the ability to establish arbitrary spin Hamiltonian by modulating the momentum of light. Arbitrary displacement-dependent spin interactions can be computed from different momenta of light, formulating as a generalized Plancherel theorem, which allows us to implement a SPIM with a minimal optical operation (that is, a single Fourier transform) to obtain the Hamiltonian of customized spin interaction. Experimentally, we unveil the exotic magnetic phase diagram of the generalized J1-J2-J3 model, shedding light on the ab initio magnetic states of iron chalcogenides. Moreover, we observe Berezinskii-Kosterlitz-Thouless dynamics by implementing an XY model. We open an avenue to controlling arbitrary spin interaction from the momentum space of light, offering a promising method for on-demand spin model simulation with a simple spatial light platform..
Advanced Photonics
- Publication Date: May. 02, 2025
- Vol. 7, Issue 4, 046001 (2025)
On-chip twisted hollow-core light cages: enhancing planar photonics with 3D nanoprinting
Johannes Bürger, Jisoo Kim, Thomas Weiss, Stefan A. Maier, and Markus A. Schmidt
Twisted optical fibers are a promising platform for manipulating circularly polarized light and orbital angular momentum beams for...show moreTwisted optical fibers are a promising platform for manipulating circularly polarized light and orbital angular momentum beams for applications such as nonlinear frequency conversion, optical communication, or chiral sensing. However, integration into chip-scale technology is challenging because twisted fibers are incompatible with planar photonics and the achieved twist rates are limited. Here, we address these challenges by introducing the concept of 3D-nanoprinted on-chip twisted hollow-core light cages. We show theoretically and experimentally that the geometrical twisting of light cages forces the fundamental core mode of a given handedness to couple with selected higher-order core modes, resulting in strong circular dichroism (CD). These chiral resonances result from the angular momentum harmonics of the fundamental mode, allowing us to predict their spectral locations and the occurrence of circular birefringence. Twisted light cages enable very high twist rates and CD, exceeding those of twisted hollow-core fibers by more than two orders of magnitude (twist period, 90 μm; CD, 0.8 dB / mm). Moreover, the unique cage design provides lateral access to the central core region, enabling future applications in chiral spectroscopy. Therefore, the presented concept opens a path for translating twisted fiber research to on-chip technology, resulting in a new platform for integrated chiral photonics..
Advanced Photonics
- Publication Date: May. 07, 2025
- Vol. 7, Issue 4, 046002 (2025)
Highly integrated all-optical nonlinear deep neural network for multi-thread processing
Jialong Zhang, Bo Wu, Shiji Zhang, Junwei Cheng... and Xinliang Zhang|Show fewer author(s)
Optical neural networks have emerged as feasible alternatives to their electronic counterparts, offering significant benefits such as low...show moreOptical neural networks have emerged as feasible alternatives to their electronic counterparts, offering significant benefits such as low power consumption, low latency, and high parallelism. However, the realization of ultra-compact nonlinear deep neural networks and multi-thread processing remain crucial challenges for optical computing. We present a monolithically integrated all-optical nonlinear diffractive deep neural network (AON-D2NN) chip for the first time. The all-optical nonlinear activation function is implemented using germanium microstructures, which provide low loss and are compatible with the standard silicon photonics fabrication process. Assisted by the germanium activation function, the classification accuracy is improved by 9.1% for four-classification tasks. In addition, the chip’s reconfigurability enables multi-task learning in situ via an innovative cross-training algorithm, yielding two task-specific inference results with accuracies of 95% and 96%, respectively. Furthermore, leveraging the wavelength-dependent response of the chip, the multi-thread nonlinear optical neural network is implemented for the first time, capable of handling two different tasks in parallel. The proposed AON-D2NN contains three hidden layers with a footprint of only 0.73 mm2. It can achieve ultra-low latency (172 ps), paving the path for realizing high-performance optical neural networks..
Advanced Photonics
- Publication Date: May. 15, 2025
- Vol. 7, Issue 4, 046003 (2025)
High-speed readout for direct light orbital angular momentum photodetector via photoelastic modulation
Dehong Yang, Chang Xu, Jiawei Lai, Zipu Fan... and Dong Sun|Show fewer author(s)
Recent progress in direct photodetection of light orbital angular momentum (OAM) based on the orbital photogalvanic effect (OPGE)...show moreRecent progress in direct photodetection of light orbital angular momentum (OAM) based on the orbital photogalvanic effect (OPGE) provides an effective way for on-chip direct electric readout of orbital angular momentum, as well as large-scale integration focal-plane array devices. However, the recognition of OAM order from photocurrent response requires the extraction of circular polarization-dependent response. To date, the operation speed of such a detector is currently at the minute level and is limited by slow mechanical polarization modulation and low OAM recognition capability. We demonstrate that the operation speed can be greatly improved via an electrical polarization modulation strategy with a photoelastic modulator (PEM) accompanied by a phase-locked readout approach with a lock-in amplifier. We demonstrate an operation speed of up to kilohertz level with this new technology in the mid-infrared region (4 μm) on an OAM detector using multilayer graphene as photosensitive material. In principle, with a new modulation and readout scheme, we can potentially increase the operation speed to megahertz with a PEM that operates at a state-of-the-art speed. Our work paves the way toward high-speed operation of direct OAM detection devices based on the OPGE effect and pushes such technology to a more practical stage for focal plane array applications..
Advanced Photonics
- Publication Date: May. 23, 2025
- Vol. 7, Issue 4, 046004 (2025)
Observation of doubly degenerate topological flatbands of edge states in strained graphene
Yongsheng Liang, Jingyan Zhan, Shiqi Xia, Daohong Song, and Zhigang Chen
Flatbands are of significant interest due to their potential for strong energy confinement and their ability to facilitate strongly...show moreFlatbands are of significant interest due to their potential for strong energy confinement and their ability to facilitate strongly correlated physics such as unconventional superconductivity and fractional quantum Hall states. When topology is incorporated into flatband systems, it further enhances flatband mode robustness against perturbations. We present the first realization of doubly degenerate topological flatbands of edge states in chiral-symmetric strained graphene. The flatband degeneracy stems from the merging of Dirac points, achieved by tuning the coupling ratios in a honeycomb lattice with newly discovered twig boundary conditions. The topology of these modes is characterized by the nontrivial winding number, which ensures their robustness against disorder. Experimentally, two types of topological edge states are observed in a strained photonic graphene lattice, consistent with numerical simulations. Moreover, the degeneracy of the topological flatbands doubles the density of states for zero-energy modes, facilitating the formation of compact edge states and providing greater control over edge states and light confinement. Our findings underscore the interplay among lattice geometry, symmetry, and topology in shaping doubly degenerate topological flatbands. This work opens new possibilities for advancements in correlated effects, nonlinear optical phenomena, and efficient energy transfer in materials science, photonic crystals, and quantum devices..
Advanced Photonics
- Publication Date: May. 23, 2025
- Vol. 7, Issue 4, 046005 (2025)
High-resolution and wide-field microscopic imaging with a monolithic meta-doublet under annular illumination
Jiacheng Sun, Wenjing Shen, Junyi Wang, Rongtao Yu... and Tao Li|Show fewer author(s)
Metalenses have exhibited significant promise across various applications due to their ultrathin, lightweight, and flat architecture,...show moreMetalenses have exhibited significant promise across various applications due to their ultrathin, lightweight, and flat architecture, which allows for integration with microelectronic devices. However, their overall imaging capabilities, particularly in microscopy, are hindered by substantial off-axis aberrations that limit both the field of view (FOV) and resolution. To address these issues, we introduce a meta-microscope that utilizes a metalens doublet incorporated with annular illumination, enabling wide FOV and high-resolution imaging in a compact design. The metalens-doublet effectively mitigates off-axis aberrations, whereas annular illumination boosts resolution. To validate this design, we constructed and tested the meta-microscope system, attaining a record resolution of 310 nm (for metalens image) with a 150 μm FOV at 470 nm wavelength. Moreover, by utilizing the integration of metasurface, we implemented a compact prototype achieving an impressive 1-mm FOV with a resolution of 620 nm. Our experimental results demonstrate high-quality microscopic bio-images that are comparable to those obtained from traditional microscopes within a compact prototype, highlighting its potential applications in portable and convenient settings, such as biomedical imaging, mobile monitoring, and outdoor research..
Advanced Photonics
- Publication Date: May. 27, 2025
- Vol. 7, Issue 4, 046006 (2025)
Bacterial identification by metabolite-level interpretable surface-enhanced Raman spectroscopy
Haoran Chen, Ruike Zhao, Xinyuan Bi, Nan Shen... and Jian Ye|Show fewer author(s)
Surface-enhanced Raman spectroscopy (SERS), as a great potential label-free tool in metabolite detection, offers a strategy for rapid...show moreSurface-enhanced Raman spectroscopy (SERS), as a great potential label-free tool in metabolite detection, offers a strategy for rapid bacterial identification. However, it still lacks experimentally supported spectral interpretation at the metabolite level for complex biosamples. We present a SERS-based method for reliable bacterial intracellular metabolic profiling using plasmonic colloids with high rapidness and cost-efficiency. A convolutional neural network model was constructed to accurately classify eight types of bacteria with an overall accuracy as high as 90.44% and identify the key spectral features for classification by Shapley Additive Explanations. Molecule-level interpretation of the SERS metabolic profiles has been further realized in combination with laser desorption/ionization mass spectrometry, evidencing the primary metabolite contribution to the bacterial spectral signatures and molecule-level distinctions among different bacterial types. We provide insights into the mechanism of bacterial identification by label-free SERS and pave the way for interpretable SERS diagnostic tools for various diseases..
Advanced Photonics
- Publication Date: Jun. 20, 2025
- Vol. 7, Issue 4, 046007 (2025)
Adaptive optical multispectral matrix approach for label-free high-resolution imaging through complex scattering media
Yiwen Zhang, Minh Dinh, Zeyu Wang, Tianhao Zhang... and Chia Wei Hsu|Show fewer author(s)
Imaging through complex scattering media is severely limited by aberrations and scattering, which obscure images and reduce...show moreImaging through complex scattering media is severely limited by aberrations and scattering, which obscure images and reduce resolution. Confocal and temporal gatings partly filter out multiple scattering but are severely degraded by wavefront distortions. Adaptive optics (AO) restore resolution by correcting low-order aberrations, and matrix-based imaging enables more complex wavefront corrections. However, they struggle to undo high-order aberrations under strong scattering, preventing imaging at greater depths. To address these challenges, we present scattering matrix tomography (SMT), an approach that makes full use of the wavefront engineering capability of scattering matrix and extreme AO. SMT reformulates imaging through complex media as a numerical optimization and employs Zernike-mode wavefront regularization and coarse-to-fine nonconvex optimization strategy to reverse severe aberrations, enabling noninvasive high-resolution volumetric imaging in multiple scattering regimes. Based on the spectrally resolved matrix measurement, SMT achieves a depth-over-resolution ratio above 900 beneath ex vivo mouse brain tissue and volumetric imaging at over three transport mean-free paths inside an opaque colloid, where conventional methods fail to correct strong aberrations under these challenging conditions. SMT is noninvasive and label-free and works both inside and outside the scattering media, making it suitable for various applications, including medical imaging, biological science, device inspection, and colloidal physics..
Advanced Photonics
- Publication Date: Jun. 28, 2025
- Vol. 7, Issue 4, 046008 (2025)
Sub-100-fs deep-red mode-locked fiber laser for multicolor two-photon microscopy
Jinhai Zou, Hongsen He, Luming Song, Lu Huang... and Zhengqian Luo|Show fewer author(s)
Visible femtosecond lasers, especially within the deep-red wavelengths, are critical for applications such as bioimaging, biomedicine, and...show moreVisible femtosecond lasers, especially within the deep-red wavelengths, are critical for applications such as bioimaging, biomedicine, and material processing. Traditional visible ultrafast lasers, such as Ti:sapphire lasers or nonlinear frequency–converted lasers, face limitations in size, cost, stability, and efficiency. Here, we demonstrate a Pr3 + -doped mode-locked fiber laser (MLFL), directly generating sub-100-fs pulses at deep-red wavelength. This approach involves theoretical optimization and experimental validation using a ring cavity with Pr3 + :ZBLAN fiber and nonlinear polarization rotation. The resulting ultrafast laser operates at 716.6 nm, delivering pulses with an ∼13-nm bandwidth and 83-fs duration at an ∼73.7-MHz repetition rate. To showcase the feasibility of this 717-nm MLFL for practical applications, two-photon microscopy is demonstrated with outstanding and unique performance regarding the simultaneous multicolor excitation of blue, green, and red dyes, enhanced resolution by 33%, and approximately four times higher excitation efficiency, compared with the conventional excitation wavelength at ∼1064 nm. These advantages confirm its versatility and reliability in biophotonic imaging. Our findings pave the way for compact, efficient sub-100-fs visible fiber lasers for multicolor bioimaging applications..
Advanced Photonics
- Publication Date: Jun. 28, 2025
- Vol. 7, Issue 4, 046009 (2025)
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