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Optical Devices|165 Article(s)
Efficient on-chip waveguide amplifiers in GeSbS-loaded etchless erbium-doped lithium niobate thin film
Chunxu Wang, Jingcui Song, Zhaohuan Ao, Yingyu Chen... and Zhaohui Li|Show fewer author(s)
In this paper, an efficient Ge25Sb10S65 (GeSbS)-loaded erbium-doped lithium niobate waveguide amplifier is demonstrated. By dimensional optimization of the waveguide, an internal net gain of approximately 28 dB and a maximum on-chip output power of 8.2 dBm are demonstrated upon 1480 nm bidirectional pumping. Due to the improved optical mode field distribution within the active erbium-doped lithium niobate film and the mode overlap ratio between the pump and signal sources, a 15% high conversion efficiency can be achieved at a modest pump power of 45 mW. Furthermore, the noise figure of the amplifier can be maintained below 6 dB for low-input-signal power levels. Compared to state-of-the-art erbium-doped waveguide amplifiers (EDWAs), this heterogeneously integrated device shows superior gain performance at the desired optical C-band while avoiding the complex plasma etching process of lithium niobate, providing an inspirative solution for power compensation in the optical telecommunications. In this paper, an efficient Ge25Sb10S65 (GeSbS)-loaded erbium-doped lithium niobate waveguide amplifier is demonstrated. By dimensional optimization of the waveguide, an internal net gain of approximately 28 dB and a maximum on-chip output power of 8.2 dBm are demonstrated upon 1480 nm bidirectional pumping. Due to the improved optical mode field distribution within the active erbium-doped lithium niobate film and the mode overlap ratio between the pump and signal sources, a 15% high conversion efficiency can be achieved at a modest pump power of 45 mW. Furthermore, the noise figure of the amplifier can be maintained below 6 dB for low-input-signal power levels. Compared to state-of-the-art erbium-doped waveguide amplifiers (EDWAs), this heterogeneously integrated device shows superior gain performance at the desired optical C-band while avoiding the complex plasma etching process of lithium niobate, providing an inspirative solution for power compensation in the optical telecommunications.
Photonics Research
- Publication Date: May. 30, 2025
- Vol. 13, Issue 6, 1674 (2025)
High-performance UV polarization sensitive photodetector for a graphene(2D)/GaN(3D) junction with a non-centrosymmetric electric field
Can Zou, Qing Liu, Lu Zhang, Xiao Tang... and Fangliang Gao|Show fewer author(s)
This study pioneers a high-performance UV polarization-sensitive photodetector by ingeniously integrating non-centrosymmetric metal nanostructures into a graphene (Gr)/Al2O3/GaN heterojunction. Unlike conventional approaches constrained by graphene’s intrinsic isotropy or complex nanoscale patterning, our design introduces asymmetric metal architectures (E-/T-type) to artificially create directional anisotropy. These structures generate plasmon-enhanced localized electric fields that selectively amplify photogenerated carrier momentum under polarized UV light (325 nm), synergized with Fowler-Nordheim tunneling (FNT) across an atomically thin Al2O3 barrier. The result is a breakthrough in performance: a record anisotropy ratio of 115.5 (E-type, -2 V) and exceptional responsivity (97.7 A/W), surpassing existing graphene-based detectors by over an order of magnitude. Crucially, by systematically modulating metal geometry and density, we demonstrate a universal platform adaptable to diverse 2D/3D systems. This study provides a valuable reference for developing and practically applying photodetectors with higher anisotropy than ultraviolet polarization sensitivity. This study pioneers a high-performance UV polarization-sensitive photodetector by ingeniously integrating non-centrosymmetric metal nanostructures into a graphene (Gr)/Al2O3/GaN heterojunction. Unlike conventional approaches constrained by graphene’s intrinsic isotropy or complex nanoscale patterning, our design introduces asymmetric metal architectures (E-/T-type) to artificially create directional anisotropy. These structures generate plasmon-enhanced localized electric fields that selectively amplify photogenerated carrier momentum under polarized UV light (325 nm), synergized with Fowler-Nordheim tunneling (FNT) across an atomically thin Al2O3 barrier. The result is a breakthrough in performance: a record anisotropy ratio of 115.5 (E-type, -2 V) and exceptional responsivity (97.7 A/W), surpassing existing graphene-based detectors by over an order of magnitude. Crucially, by systematically modulating metal geometry and density, we demonstrate a universal platform adaptable to diverse 2D/3D systems. This study provides a valuable reference for developing and practically applying photodetectors with higher anisotropy than ultraviolet polarization sensitivity.
Photonics Research
- Publication Date: May. 27, 2025
- Vol. 13, Issue 6, 1544 (2025)
All-fiber-optic mass sensor based on optomechanical nanofilm resonators
Qiao Lin, Xin Ding, Weiguan Zhang, Yueliang Xiao... and Shen Liu|Show fewer author(s)
Mass detection plays an indispensable role in many fields like medical targeted therapy, biological cytology, and nanophysics. However, traditional mass detection faces the challenge of a complex system, expensive instruments, and long testing time. Here we report an all-fiber-optic mass sensor based on a nanofilm resonator. Using resonant frequency shifts as the readout of analyte mass, the sensor achieves the mass sensitivity of 0.920 kHz/pg with a mass resolution of 1.9×10-14 g, for the first-order mode in the mass range up to 372 pg at room temperature. In this work, we transfer the excitation laser and detection laser to the micro-cavity structure at the end of the optical fiber. Combined with optical fibers, the sensor can be made extremely integrated, making it more stable and collimation-free compared with traditional bulky optical setups. Its good biocompatibility and anti-electromagnetism disturbance ability also make this mass sensor potentially a beneficial tool for cell biology and basic physics measurements. Mass detection plays an indispensable role in many fields like medical targeted therapy, biological cytology, and nanophysics. However, traditional mass detection faces the challenge of a complex system, expensive instruments, and long testing time. Here we report an all-fiber-optic mass sensor based on a nanofilm resonator. Using resonant frequency shifts as the readout of analyte mass, the sensor achieves the mass sensitivity of 0.920 kHz/pg with a mass resolution of 1.9×10-14 g, for the first-order mode in the mass range up to 372 pg at room temperature. In this work, we transfer the excitation laser and detection laser to the micro-cavity structure at the end of the optical fiber. Combined with optical fibers, the sensor can be made extremely integrated, making it more stable and collimation-free compared with traditional bulky optical setups. Its good biocompatibility and anti-electromagnetism disturbance ability also make this mass sensor potentially a beneficial tool for cell biology and basic physics measurements.
Photonics Research
- Publication Date: May. 27, 2025
- Vol. 13, Issue 6, 1526 (2025)
High-efficiency mode group demultiplexing based on diffractive optical network
Zhibing Liu, Siqing Zeng, Shuixian Yang, Yuetong Shi... and Zhaohui Li|Show fewer author(s)
Space division multiplexing (SDM) can achieve higher communication transmission capacity by exploiting more spatial channels in a single optical fiber. For weakly coupled few-mode fiber, different mode groups (MGs) are highly isolated from each other, so the SDM system can be simplified by utilizing MG multiplexing and intensity modulation direct detection. A key issue to be addressed here is MG demultiplexing, which requires processing all the modes within a single MG in contrast to MG multiplexing. Benefiting from the great light manipulation freedom of the diffractive optical network (DON), we achieve efficient separation of the MGs and receive them with the multimode fiber (MMF) array. To fully exploit the mode field freedom of the MMF, a non-deterministic mode conversion strategy is proposed here to optimize the DON, which enables high-efficiency demultiplexing with a much smaller number of phase plates. As a validation, we design a 6-MG demultiplexer consisting of only five phase plates; each MG is constituted by several orbital angular momentum modes. The designed average loss and crosstalk at the wavelength of 1550 nm are 0.5 dB and -25 dB, respectively. In the experiment, the loss after coupling to the MMF ranged from 4.1 to 4.9 dB, with an average of 4.5 dB. The inter-MG crosstalk is better than -12 dB, with an average of -18 dB. These results well support the proposed scheme and will provide a practical solution to the MG demultiplexing problem in a short-distance SDM system. Space division multiplexing (SDM) can achieve higher communication transmission capacity by exploiting more spatial channels in a single optical fiber. For weakly coupled few-mode fiber, different mode groups (MGs) are highly isolated from each other, so the SDM system can be simplified by utilizing MG multiplexing and intensity modulation direct detection. A key issue to be addressed here is MG demultiplexing, which requires processing all the modes within a single MG in contrast to MG multiplexing. Benefiting from the great light manipulation freedom of the diffractive optical network (DON), we achieve efficient separation of the MGs and receive them with the multimode fiber (MMF) array. To fully exploit the mode field freedom of the MMF, a non-deterministic mode conversion strategy is proposed here to optimize the DON, which enables high-efficiency demultiplexing with a much smaller number of phase plates. As a validation, we design a 6-MG demultiplexer consisting of only five phase plates; each MG is constituted by several orbital angular momentum modes. The designed average loss and crosstalk at the wavelength of 1550 nm are 0.5 dB and -25 dB, respectively. In the experiment, the loss after coupling to the MMF ranged from 4.1 to 4.9 dB, with an average of 4.5 dB. The inter-MG crosstalk is better than -12 dB, with an average of -18 dB. These results well support the proposed scheme and will provide a practical solution to the MG demultiplexing problem in a short-distance SDM system.
Photonics Research
- Publication Date: May. 01, 2025
- Vol. 13, Issue 5, 1400 (2025)
Dual-frequency-range modulator based on a planar nested multiscale metasurface
Jing Yuan, Guichuan Xu, Zhengang Lu, Xinmeng Zhuang... and Jiubin Tan|Show fewer author(s)
Multi-spectral and multi-functional optical components play a crucial role in fields such as high-speed communications and optical sensing. However, the interaction between different spectra and matter varies significantly, making it challenging to simultaneously achieve dynamic multi-spectral modulation capabilities. We designed a modulator based on a planar nested multiscale metasurface, incorporating silicon (Si) and perovskite as control materials, to modulate both microwave and terahertz (THz) ranges. Modulation of microwave and THz waves is achieved through visible light and near-infrared light pumping, with modulation depths of 94.03% and 90.77%, respectively. The modulator employs a planar nested multiscale metasurface, utilizing the odd-order nonlinear polarization properties of perovskite in the THz range and the linear absorption properties of Si in the microwave range to realize dual-frequency-range modulation. This research offers innovative insights for designing multi-spectral components applicable in all-optical coding metasurfaces and intelligent light windows. Multi-spectral and multi-functional optical components play a crucial role in fields such as high-speed communications and optical sensing. However, the interaction between different spectra and matter varies significantly, making it challenging to simultaneously achieve dynamic multi-spectral modulation capabilities. We designed a modulator based on a planar nested multiscale metasurface, incorporating silicon (Si) and perovskite as control materials, to modulate both microwave and terahertz (THz) ranges. Modulation of microwave and THz waves is achieved through visible light and near-infrared light pumping, with modulation depths of 94.03% and 90.77%, respectively. The modulator employs a planar nested multiscale metasurface, utilizing the odd-order nonlinear polarization properties of perovskite in the THz range and the linear absorption properties of Si in the microwave range to realize dual-frequency-range modulation. This research offers innovative insights for designing multi-spectral components applicable in all-optical coding metasurfaces and intelligent light windows.
Photonics Research
- Publication Date: May. 01, 2025
- Vol. 13, Issue 5, 1390 (2025)
Efficient inverse design for tailoring a terahertz metagrating
Jia Shi, Guanlong Wang, Shaona Wang, Wenjing Yu... and Xiang Yang|Show fewer author(s)
The fast and accurate design of terahertz devices for specific applications remains challenging, especially for tailoring metadevices, owing to the complex electromagnetic characteristics of these devices and their large structural parameter space. The unique functionalities achieved by metadevices come at the cost of structural complexity, resulting in a time-consuming parameter sweep for conventional metadevice design. Here, we propose a general solution to achieve efficient inverse design for a terahertz metagrating via machine learning. Metagratings with different structural parameters were selected as illustrations to verify the effectiveness of this method. As proof-of-principle examples, the metagratings predicted via the inverse design model are numerically calculated and experimentally demonstrated. Initially, the physical modeling of a metagrating is performed via the finite element method (FEM). A spectrum dataset obtained from FEM simulation is prepared for the training of machine learning models. Then, trained machine learning models, including the Elman neural network (Elman), support vector machine (SVM), and general regression neutral network (GRNN), are used to predict probable structural parameters. The results of these models are compared and analyzed comprehensively, which verifies the effectiveness of the inverse design method. Compared with conventional methods, the inverse design method is much faster and can encompass a high degree of freedom to generate metadevice structures, which can ensure that the spectra of generated structures resemble the desired ones and can provide accurate data support for metadevice modeling. Furthermore, a metagrating tailored by an inverse design is used as a biological sensor to distinguish different microorganisms. The proposed data-driven inverse design method realizes fast and accurate design of the metagrating, which is expected to have great potential in metadevice design and tailoring for specific applications. The fast and accurate design of terahertz devices for specific applications remains challenging, especially for tailoring metadevices, owing to the complex electromagnetic characteristics of these devices and their large structural parameter space. The unique functionalities achieved by metadevices come at the cost of structural complexity, resulting in a time-consuming parameter sweep for conventional metadevice design. Here, we propose a general solution to achieve efficient inverse design for a terahertz metagrating via machine learning. Metagratings with different structural parameters were selected as illustrations to verify the effectiveness of this method. As proof-of-principle examples, the metagratings predicted via the inverse design model are numerically calculated and experimentally demonstrated. Initially, the physical modeling of a metagrating is performed via the finite element method (FEM). A spectrum dataset obtained from FEM simulation is prepared for the training of machine learning models. Then, trained machine learning models, including the Elman neural network (Elman), support vector machine (SVM), and general regression neutral network (GRNN), are used to predict probable structural parameters. The results of these models are compared and analyzed comprehensively, which verifies the effectiveness of the inverse design method. Compared with conventional methods, the inverse design method is much faster and can encompass a high degree of freedom to generate metadevice structures, which can ensure that the spectra of generated structures resemble the desired ones and can provide accurate data support for metadevice modeling. Furthermore, a metagrating tailored by an inverse design is used as a biological sensor to distinguish different microorganisms. The proposed data-driven inverse design method realizes fast and accurate design of the metagrating, which is expected to have great potential in metadevice design and tailoring for specific applications.
Photonics Research
- Publication Date: Apr. 21, 2025
- Vol. 13, Issue 5, 1172 (2025)
QBIC-based terahertz metasurface used for the detection of chlorpyrifos in tea
Tianqing Zhou, Binggang Xiao, Yong Du, and Jianyuan Qin
Pesticide residues in tea are an important problem affecting the sustainable development of the tea industry; thus, pesticide detection is the key to ensuring the quality and safety of tea. Here, a terahertz metasurface structure based on the quasi-bound state in the continuum is proposed, which consists of two copper microrods arranged periodically. This design in the metasurface provides strong local enhancement near the surface of the microstructure, significantly improving the interaction of light with the analyte, resulting in increased sensitivity. The simulated and experimental results show that the metasurface structure can be used to detect the refractive index of trace analytes with a high sensitivity and successfully detect low concentrations of chlorpyrifos in tea. This study provides a new idea for the detection of pesticide residues in tea. Pesticide residues in tea are an important problem affecting the sustainable development of the tea industry; thus, pesticide detection is the key to ensuring the quality and safety of tea. Here, a terahertz metasurface structure based on the quasi-bound state in the continuum is proposed, which consists of two copper microrods arranged periodically. This design in the metasurface provides strong local enhancement near the surface of the microstructure, significantly improving the interaction of light with the analyte, resulting in increased sensitivity. The simulated and experimental results show that the metasurface structure can be used to detect the refractive index of trace analytes with a high sensitivity and successfully detect low concentrations of chlorpyrifos in tea. This study provides a new idea for the detection of pesticide residues in tea.
Photonics Research
- Publication Date: Apr. 21, 2025
- Vol. 13, Issue 5, 1158 (2025)
High-efficiency multi-channel focusing and imaging enabled by polarization-frequency multiplexing non-interleaved metasurfaces
Xunjun He, Mingzhong Wu, Guangjun Lu, Ying Zhang, and Zhaoxin Geng
In microwave communication systems, focusing and imaging have attracted widespread attention due to their application prospects in the information processing and communication fields. Most existing multi-channel focusing and imaging are implemented by interleaved metasurfaces. However, the disadvantages of their large size and low efficiency limit their practical applications in large-capacity and low-loss integrated systems. To solve these issues, here, we propose a non-interleaved polarization-frequency multiplexing metasurface for high-efficiency multi-channel focusing and imaging. The meta-atoms of the non-interleaved metasurface are composed of a metallic ground plate, two dielectric layers, a larger cross-shaped metal structure, and a smaller cross-shaped metal structure embedded by a circular metal aperture. By altering the size of two cross-shaped structures, the designed meta-atom can obtain the independent complete 2π phase coverage with high reflection efficiency at two different frequency ranges for two orthogonal linear polarization (LP) incidences, realizing polarization multiplexing and frequency multiplexing. Moreover, two types of metasurfaces based on the above meta-atoms are designed to realize multi-channel focusing and imaging with high efficiency. As a proof, the focusing metasurface is fabricated and measured, and the measured results are well consistent with simulated results. Therefore, the proposed scheme has the advantages of high efficiency, multi-channel, and compact size, which possesses broad application prospects in low-loss and multi-channel communication integrated systems. In microwave communication systems, focusing and imaging have attracted widespread attention due to their application prospects in the information processing and communication fields. Most existing multi-channel focusing and imaging are implemented by interleaved metasurfaces. However, the disadvantages of their large size and low efficiency limit their practical applications in large-capacity and low-loss integrated systems. To solve these issues, here, we propose a non-interleaved polarization-frequency multiplexing metasurface for high-efficiency multi-channel focusing and imaging. The meta-atoms of the non-interleaved metasurface are composed of a metallic ground plate, two dielectric layers, a larger cross-shaped metal structure, and a smaller cross-shaped metal structure embedded by a circular metal aperture. By altering the size of two cross-shaped structures, the designed meta-atom can obtain the independent complete 2π phase coverage with high reflection efficiency at two different frequency ranges for two orthogonal linear polarization (LP) incidences, realizing polarization multiplexing and frequency multiplexing. Moreover, two types of metasurfaces based on the above meta-atoms are designed to realize multi-channel focusing and imaging with high efficiency. As a proof, the focusing metasurface is fabricated and measured, and the measured results are well consistent with simulated results. Therefore, the proposed scheme has the advantages of high efficiency, multi-channel, and compact size, which possesses broad application prospects in low-loss and multi-channel communication integrated systems.
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 976 (2025)
All-fiber orbital-angular-momentum mode encoding system based on helical fiber gratings
Yu Chen, Ming Gao, Yutao Wang, Xinyue Huang... and Hongpu Li|Show fewer author(s)
In this study, we propose and demonstrate an all-fiber orbital-angular-momentum (OAM) mode encoding system, where through helical fiber gratings (HFGs), binary symbols are encoded to or decoded from two OAM modes with topological charges (TCs) of -1 and +1, respectively. We experimentally validate that the OAM mode generated by a clockwise-helix HFG (cHFG) can be converted back into fundamental mode by using an HFG with a helix orientation opposite to that of the cHFG, i.e., ccHFG. Benefited from utilization of the HFGs, the proposed OAM mode encoding system has a low cost, low insertion loss, high mode conversion efficiency, and polarization independence. To the best of our knowledge, this is the first demonstration of the HFGs-based all-fiber OAM mode encoding/decoding scheme, which may find potential applications in optical communication and quantum communication as well. In this study, we propose and demonstrate an all-fiber orbital-angular-momentum (OAM) mode encoding system, where through helical fiber gratings (HFGs), binary symbols are encoded to or decoded from two OAM modes with topological charges (TCs) of -1 and +1, respectively. We experimentally validate that the OAM mode generated by a clockwise-helix HFG (cHFG) can be converted back into fundamental mode by using an HFG with a helix orientation opposite to that of the cHFG, i.e., ccHFG. Benefited from utilization of the HFGs, the proposed OAM mode encoding system has a low cost, low insertion loss, high mode conversion efficiency, and polarization independence. To the best of our knowledge, this is the first demonstration of the HFGs-based all-fiber OAM mode encoding/decoding scheme, which may find potential applications in optical communication and quantum communication as well.
Photonics Research
- Publication Date: Apr. 01, 2025
- Vol. 13, Issue 4, 960 (2025)
Visible-near infrared broadband photodetector enabled by a photolithography-defined plasmonic disk array
Huafeng Dong, Qianxi Yin, Ziqiao Wu, Yufan Ye... and Jiancai Xue|Show fewer author(s)
2D-material-based photodetectors enhanced by plasmonic nanostructures can support responsivity/detectivity several orders higher than commercial photodetectors, drawing extensive attention as promising candidates for the next-generation photodetectors. However, to boost the nanostructure-enhanced 2D photodetectors into real-world applications, crucial challenges lie in the design of broadband enhancing nanostructures and their scalable and position-controllable fabrication. Here, based on a broadband resonant plasmonic disk array fabricated by a scalable and position-controllable technique (direct writing photolithography), we present a visible-near infrared (405–1310 nm) 2D WS2 photodetector, whose detectivity is up to 3.9×1014 Jones, a value exceeding that of the previous plasmon-enhanced 2D photodetectors. The broadened spectral response range and the high detectivity originate from the hot electron injection, optical absorption enhancement, and strain effect supported by the plasmonic array. Furthermore, the designed plasmonic 2D photodetector supports self-powered photodetection, indicating promising potential in energy-free and portable optoelectronic systems. Our results demonstrate an effective method to construct high-performance broadband photodetectors, which can facilitate the development of 2D photodetectors in commercial applications. 2D-material-based photodetectors enhanced by plasmonic nanostructures can support responsivity/detectivity several orders higher than commercial photodetectors, drawing extensive attention as promising candidates for the next-generation photodetectors. However, to boost the nanostructure-enhanced 2D photodetectors into real-world applications, crucial challenges lie in the design of broadband enhancing nanostructures and their scalable and position-controllable fabrication. Here, based on a broadband resonant plasmonic disk array fabricated by a scalable and position-controllable technique (direct writing photolithography), we present a visible-near infrared (405–1310 nm) 2D WS2 photodetector, whose detectivity is up to 3.9×1014 Jones, a value exceeding that of the previous plasmon-enhanced 2D photodetectors. The broadened spectral response range and the high detectivity originate from the hot electron injection, optical absorption enhancement, and strain effect supported by the plasmonic array. Furthermore, the designed plasmonic 2D photodetector supports self-powered photodetection, indicating promising potential in energy-free and portable optoelectronic systems. Our results demonstrate an effective method to construct high-performance broadband photodetectors, which can facilitate the development of 2D photodetectors in commercial applications.
Photonics Research
- Publication Date: Jan. 30, 2025
- Vol. 13, Issue 2, 453 (2025)
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