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Optical Devices|156 Article(s)
Visible-near infrared broadband photodetector enabled by a photolithography-defined plasmonic disk array
Huafeng Dong, Qianxi Yin, Ziqiao Wu, Yufan Ye, Rongxi Li, Ziming Meng, and Jiancai Xue
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)
Optical neural networks based on perovskite solar cells
Kaicheng Zhang, Jonathon Harwell, Davide Pierangeli, Claudio Conti, and Andrea Di Falco
Optical neural networks (ONNs) are a class of emerging computing platforms that leverage the properties of light to perform ultra-fast computations with ultra-low energy consumption. ONNs often use CCD cameras as the output layer. In this work, we propose the use of perovskite solar cells as a promising alternative to imaging cameras in ONN designs. Solar cells are ubiquitous, versatile, highly customizable, and can be fabricated quickly in laboratories. Their large acquisition area and outstanding efficiency enable them to generate output signals with a large dynamic range without the need for amplification. Here we have experimentally demonstrated the feasibility of using perovskite solar cells for capturing ONN output states, as well as the capability of single-layer random ONNs to achieve excellent performance even with a very limited number of pixels. Our results show that the solar-cell-based ONN setup consistently outperforms the same setup with CCD cameras of the same resolution. These findings highlight the potential of solar-cell-based ONNs as an ideal choice for automated and battery-free edge-computing applications. Optical neural networks (ONNs) are a class of emerging computing platforms that leverage the properties of light to perform ultra-fast computations with ultra-low energy consumption. ONNs often use CCD cameras as the output layer. In this work, we propose the use of perovskite solar cells as a promising alternative to imaging cameras in ONN designs. Solar cells are ubiquitous, versatile, highly customizable, and can be fabricated quickly in laboratories. Their large acquisition area and outstanding efficiency enable them to generate output signals with a large dynamic range without the need for amplification. Here we have experimentally demonstrated the feasibility of using perovskite solar cells for capturing ONN output states, as well as the capability of single-layer random ONNs to achieve excellent performance even with a very limited number of pixels. Our results show that the solar-cell-based ONN setup consistently outperforms the same setup with CCD cameras of the same resolution. These findings highlight the potential of solar-cell-based ONNs as an ideal choice for automated and battery-free edge-computing applications.
Photonics Research
- Publication Date: Jan. 28, 2025
- Vol. 13, Issue 2, 382 (2025)
High-efficiency focusing metalens based on metagrating arrays
Jia Shi, Guanlong Wang, Longhuang Tang, Xiang Wang, Shaona Wang, Cuijuan Guo, Hua Bai, Pingjuan Niu, Jianquan Yao, and Jidong Weng
The flexible and precise control of wavefronts of electromagnetic waves has always been a hot issue, and the emergence of metasurfaces has provided a platform to solve this problem, but their design and optimization remain challenging. Here, we demonstrate two design and optimization methods for metagrating-based metalenses based on the highest manipulation efficiency and highest diffraction efficiency. The metalens operating at 0.14 THz with numerical apertures of 0.434 is designed by these two methods for comparison. Then, the metalens is fabricated with photocuring 3D printing technology and an imaging system is built to characterize the distribution of focal spots. With the highest manipulation efficiency, the metalens shows a focal spot with the diameter of 0.93λ and depth of focus (DOF) of 22.7λ, and the manipulation and diffraction efficiencies reach 98.1% and 58.3%. With the highest diffraction efficiency, the metalens shows a focal spot with the diameter of 0.91λ and DOF of 24.6λ, and the manipulation and diffraction efficiencies reach 94.6% and 62.5%. The results show that the metalenses designed by both methods can perform a filamentous focal spot in the sub-wavelength scale with a long DOF; simultaneous high manipulation and diffraction efficiencies are obtained. A transmission imaging manner is used to verify the imaging capability of the metalenses, and the measurements are satisfactorily congruous with the anticipated results. The proposed methods can stably generate focal spots beyond the physical diffraction limit, which has a broad application in terahertz imaging, communications, etc. The flexible and precise control of wavefronts of electromagnetic waves has always been a hot issue, and the emergence of metasurfaces has provided a platform to solve this problem, but their design and optimization remain challenging. Here, we demonstrate two design and optimization methods for metagrating-based metalenses based on the highest manipulation efficiency and highest diffraction efficiency. The metalens operating at 0.14 THz with numerical apertures of 0.434 is designed by these two methods for comparison. Then, the metalens is fabricated with photocuring 3D printing technology and an imaging system is built to characterize the distribution of focal spots. With the highest manipulation efficiency, the metalens shows a focal spot with the diameter of 0.93λ and depth of focus (DOF) of 22.7λ, and the manipulation and diffraction efficiencies reach 98.1% and 58.3%. With the highest diffraction efficiency, the metalens shows a focal spot with the diameter of 0.91λ and DOF of 24.6λ, and the manipulation and diffraction efficiencies reach 94.6% and 62.5%. The results show that the metalenses designed by both methods can perform a filamentous focal spot in the sub-wavelength scale with a long DOF; simultaneous high manipulation and diffraction efficiencies are obtained. A transmission imaging manner is used to verify the imaging capability of the metalenses, and the measurements are satisfactorily congruous with the anticipated results. The proposed methods can stably generate focal spots beyond the physical diffraction limit, which has a broad application in terahertz imaging, communications, etc.
Photonics Research
- Publication Date: Jan. 17, 2025
- Vol. 13, Issue 2, 351 (2025)
Dynamic generation of multiplexed vortex beams by a space-time-coding metasurface
Pengcheng Tang, Liming Si, Qianqian Yuan, Jie Tian, Jiaxuan Deng, Tianyu Ma, Xiue Bao, Chong He, and Weiren Zhu
Dynamic generation of multimode vortex waves carrying orbital angular momentum (OAM) utilizing programmable metasurfaces has attracted considerable attention. Yet, it is still a challenge to achieve multiplexed vortex waves with an arbitrary customized mode combination, stemming fundamentally from the discrete control over phase exhibited by current programmable metasurfaces, which are typically constrained to a limited 1-bit or 2-bit discrete resolution. In this paper, we propose, to our knowledge, a new strategy for dynamic generation of multiplexed vortex beams based on a space-time-coding metasurface, capable of quasi-continuous complex-amplitude modulation for harmonic waves. As a proof of concept, a metasurface prototype for generating multiplexed vortex beams with the customized mode composition and power allocation is established based on the transmissive space-time-coding meta-atoms regulated by the field programmable gate array controller. The mode purity of the vortex beams with a single OAM mode of +1, +2, and +3 generated by the metasurface is as high as over 0.93. The generated multiplexed vortex beams carrying (+1, +2, +3) OAM modes with a power ratio of 1:1:1, (+1, +2, +3) modes with a power ratio of 1:2:3, and (-2, -1, +1, +2) modes with a power ratio of 1:2:2:1 are further verified effectively. The proposed space-time-coding metasurface has great potential for OAM multiplexing communication systems. Dynamic generation of multimode vortex waves carrying orbital angular momentum (OAM) utilizing programmable metasurfaces has attracted considerable attention. Yet, it is still a challenge to achieve multiplexed vortex waves with an arbitrary customized mode combination, stemming fundamentally from the discrete control over phase exhibited by current programmable metasurfaces, which are typically constrained to a limited 1-bit or 2-bit discrete resolution. In this paper, we propose, to our knowledge, a new strategy for dynamic generation of multiplexed vortex beams based on a space-time-coding metasurface, capable of quasi-continuous complex-amplitude modulation for harmonic waves. As a proof of concept, a metasurface prototype for generating multiplexed vortex beams with the customized mode composition and power allocation is established based on the transmissive space-time-coding meta-atoms regulated by the field programmable gate array controller. The mode purity of the vortex beams with a single OAM mode of +1, +2, and +3 generated by the metasurface is as high as over 0.93. The generated multiplexed vortex beams carrying (+1, +2, +3) OAM modes with a power ratio of 1:1:1, (+1, +2, +3) modes with a power ratio of 1:2:3, and (-2, -1, +1, +2) modes with a power ratio of 1:2:2:1 are further verified effectively. The proposed space-time-coding metasurface has great potential for OAM multiplexing communication systems.
Photonics Research
- Publication Date: Dec. 24, 2024
- Vol. 13, Issue 1, 225 (2025)
Freestanding metamaterial with constant coupling response for terahertz flexible functional devices
Qiuming Zeng, Tingting Shi, Yi Huang, Shuncong Zhong, Fuwei Sun, Chenglong Guan, Jianxiong Chen, Tingling Lin, Yujie Zhong, and Yonglin Huang
Metamaterials (MMs) have become increasingly prominent in terahertz flexible devices. However, bending deformation often alters the structure of the unit, which affects the response performance and stability of MMs. Here, a metal-aperture metamaterial (MA-MM) utilizing the strong coupling effect induced by two resonance modes is innovatively proposed to address the mentioned limitations. Specifically, it is found that the coupling state between multiple resonance modes remains consistent at different bending angles. Under these circumstances, the generated Rabi splitting peak presents stable response performance even under low resonance intensity caused by excessive deformation. The experimental results demonstrate that despite the amplitude of two resonant peaks decreasing significantly by 87.6%, the Q-factor of the Rabi splitting only reduced by 14.8%. Furthermore, armed with the response mode of the Rabi splitting being unaffected by plasma excitation range, the designed MA-MMs are able to maintain constant Q-factors and frequencies on curved surfaces of varying sizes. These findings exhibit the characteristics of electromagnetic response for multi-mode resonance-coupled MA-MMs on different curved surfaces, presenting a novel design approach for terahertz flexible functional devices. Metamaterials (MMs) have become increasingly prominent in terahertz flexible devices. However, bending deformation often alters the structure of the unit, which affects the response performance and stability of MMs. Here, a metal-aperture metamaterial (MA-MM) utilizing the strong coupling effect induced by two resonance modes is innovatively proposed to address the mentioned limitations. Specifically, it is found that the coupling state between multiple resonance modes remains consistent at different bending angles. Under these circumstances, the generated Rabi splitting peak presents stable response performance even under low resonance intensity caused by excessive deformation. The experimental results demonstrate that despite the amplitude of two resonant peaks decreasing significantly by 87.6%, the Q-factor of the Rabi splitting only reduced by 14.8%. Furthermore, armed with the response mode of the Rabi splitting being unaffected by plasma excitation range, the designed MA-MMs are able to maintain constant Q-factors and frequencies on curved surfaces of varying sizes. These findings exhibit the characteristics of electromagnetic response for multi-mode resonance-coupled MA-MMs on different curved surfaces, presenting a novel design approach for terahertz flexible functional devices.
Photonics Research
- Publication Date: Dec. 24, 2024
- Vol. 13, Issue 1, 177 (2025)
Plasmonically enhanced solar-blind self-powered photodetector array utilizing Pt nanoparticles-modified Ga2O3 nanorod heterojunction
Qinzhi Zhao, Lingfeng Mao, Peng Wan, Lijian Li, Kai Tang, Caixia Kan, Daning Shi, Xiaoxuan Wang, and Mingming Jiang
Low-dimensional Ga2O3 monocrystalline micro/nanostructures show promising application prospects in large-area arrays, integrated circuits, and flexible optoelectronic devices, owing to their exceptional optoelectronic performance and scalability for mass production. Herein, we developed an 8×8 array of high-performance solar-blind ultraviolet photodetectors based on Pt nanoparticles-modified Ga2O3 (PtNPs@Ga2O3) nanorod film heterojunction with p-GaN substrate serving as the hole transporting layer. The PtNPs@Ga2O3/GaN heterojunction detector units exhibit outstanding photovoltaic performance at 0 V bias, demonstrating high responsivity (189.0 mA/W), specific detectivity (4.0×1012 Jones), external quantum efficiency (92.4%), and swift response time (674/692 µs) under an irradiance of 1 μW/cm2 at 254 nm. Their exceptional performance stands out among competitors of the same type. In addition, the detector array demonstrated satisfactory results in a conceptual demonstration of high-resolution imaging, benefiting from the excellent stability and uniformity exhibited by its array units. These findings provide a straightforward and viable method for developing a high-performance solar-blind ultraviolet detector array based on low-dimensional Ga2O3 nanorod monocrystalline, demonstrating their potential advancement in large-area, integrable, and flexible optoelectronic devices. Low-dimensional Ga2O3 monocrystalline micro/nanostructures show promising application prospects in large-area arrays, integrated circuits, and flexible optoelectronic devices, owing to their exceptional optoelectronic performance and scalability for mass production. Herein, we developed an 8×8 array of high-performance solar-blind ultraviolet photodetectors based on Pt nanoparticles-modified Ga2O3 (PtNPs@Ga2O3) nanorod film heterojunction with p-GaN substrate serving as the hole transporting layer. The PtNPs@Ga2O3/GaN heterojunction detector units exhibit outstanding photovoltaic performance at 0 V bias, demonstrating high responsivity (189.0 mA/W), specific detectivity (4.0×1012 Jones), external quantum efficiency (92.4%), and swift response time (674/692 µs) under an irradiance of 1 μW/cm2 at 254 nm. Their exceptional performance stands out among competitors of the same type. In addition, the detector array demonstrated satisfactory results in a conceptual demonstration of high-resolution imaging, benefiting from the excellent stability and uniformity exhibited by its array units. These findings provide a straightforward and viable method for developing a high-performance solar-blind ultraviolet detector array based on low-dimensional Ga2O3 nanorod monocrystalline, demonstrating their potential advancement in large-area, integrable, and flexible optoelectronic devices.
Photonics Research
- Publication Date: Dec. 20, 2024
- Vol. 13, Issue 1, 140 (2025)
Integrated interferometers’ system for in situ real-time optical signal modulation
Kalipada Chatterjee, Jan Nedoma, Venugopal Arumuru, Subrat Sahu, Carlos Marques, and Rajan Jha
Improving the functionality of an optical sensor on a prefabricated platform relies heavily on an optical signal conditioning method that actively modulates optical signals. In this work, we present a method for active modulation of an optical sensor response that uses fiber modal interferometers integrated in parallel. Over a broad frequency range of 1 Hz to 1 kHz, the interferometers’ technology allows for adjustable amplification, attenuation, and filtering of dynamic signals. The suggested method is also used to enhance the real-time response of an optical fluid flowmeter. In order to keep tabs on different physical fields, the suggested approach promotes the creation of self-conditioning sensing systems. Improving the functionality of an optical sensor on a prefabricated platform relies heavily on an optical signal conditioning method that actively modulates optical signals. In this work, we present a method for active modulation of an optical sensor response that uses fiber modal interferometers integrated in parallel. Over a broad frequency range of 1 Hz to 1 kHz, the interferometers’ technology allows for adjustable amplification, attenuation, and filtering of dynamic signals. The suggested method is also used to enhance the real-time response of an optical fluid flowmeter. In order to keep tabs on different physical fields, the suggested approach promotes the creation of self-conditioning sensing systems.
Photonics Research
- Publication Date: Aug. 30, 2024
- Vol. 12, Issue 9, 2018 (2024)
Routing impact of architecture and damage in programmable photonic meshes
Ferre Vanden Kerchove, Didier Colle, Wouter Tavernier, Wim Bogaerts, and Mario Pickavet
Programmable photonic integrated circuits (PPICs) emerge as a novel technology with an enormous potential for ground-breaking innovation. Different architectures are currently being considered that dictate how waveguides should be connected to realize a broadly usable circuit. We focus on the effect of varying connectivity architectures on the routing of light. Three types of uniform meshes are studied, and we introduce a newly developed mesh that is called ring-connected straight lines. We provide an analytical formula to calculate exact distances in these meshes and introduce several metrics relating to routing to compare these meshes. We show that hexagonal tiles are the most promising, but the ring-connected straight lines architecture has a use case as well. Besides this, the effect of defect couplers is also studied. We find that the effects of these failures vary greatly by type and severity on the routability of the mesh. Programmable photonic integrated circuits (PPICs) emerge as a novel technology with an enormous potential for ground-breaking innovation. Different architectures are currently being considered that dictate how waveguides should be connected to realize a broadly usable circuit. We focus on the effect of varying connectivity architectures on the routing of light. Three types of uniform meshes are studied, and we introduce a newly developed mesh that is called ring-connected straight lines. We provide an analytical formula to calculate exact distances in these meshes and introduce several metrics relating to routing to compare these meshes. We show that hexagonal tiles are the most promising, but the ring-connected straight lines architecture has a use case as well. Besides this, the effect of defect couplers is also studied. We find that the effects of these failures vary greatly by type and severity on the routability of the mesh.
Photonics Research
- Publication Date: Aug. 29, 2024
- Vol. 12, Issue 9, 1999 (2024)
Optical frequency comb significantly spanned to broadband by an optomechanical resonance
Xin Gu, Jinlian Zhang, Shulin Ding, Xiaoshun Jiang, Bing He, and Qing Lin
An optical frequency comb, as a spectrum made of discrete and equally spaced spectral lines, is a light source with essential applications in modern technology. Cavity optomechanical systems were found to be a feasible candidate for realizing an on-chip frequency comb with low repetition rate. However, it was difficult to increase the comb line numbers of this type of frequency combs because the mechanical oscillation amplitude of such a system, which determines the frequency comb bandwidth, cannot quickly increase with pump laser power. Here, we develop a new approach to generate a broadband optomechanical frequency comb by employing a different mechanism to enhance the mechanical oscillation. Two pump tones with their frequency difference matching the mechanical frequency will drive the system into a self-organized nonlinear resonance and thus tremendously transfer the energy to the mechanical resonator. As a result, more than 10,000 or even more comb lines become available under the pump laser power of the order of milliwatts. A unique feature of the self-organized resonance is the mechanical frequency locking so that, within a certain range of the frequency difference between two drive tones, the distance between comb teeth can be locked by the two drive tones and becomes independent of any change of pump power. This property guarantees a stable repetition rate of the generated frequency comb. An optical frequency comb, as a spectrum made of discrete and equally spaced spectral lines, is a light source with essential applications in modern technology. Cavity optomechanical systems were found to be a feasible candidate for realizing an on-chip frequency comb with low repetition rate. However, it was difficult to increase the comb line numbers of this type of frequency combs because the mechanical oscillation amplitude of such a system, which determines the frequency comb bandwidth, cannot quickly increase with pump laser power. Here, we develop a new approach to generate a broadband optomechanical frequency comb by employing a different mechanism to enhance the mechanical oscillation. Two pump tones with their frequency difference matching the mechanical frequency will drive the system into a self-organized nonlinear resonance and thus tremendously transfer the energy to the mechanical resonator. As a result, more than 10,000 or even more comb lines become available under the pump laser power of the order of milliwatts. A unique feature of the self-organized resonance is the mechanical frequency locking so that, within a certain range of the frequency difference between two drive tones, the distance between comb teeth can be locked by the two drive tones and becomes independent of any change of pump power. This property guarantees a stable repetition rate of the generated frequency comb.
Photonics Research
- Publication Date: Aug. 29, 2024
- Vol. 12, Issue 9, 1981 (2024)
Terahertz wide range phase manipulation with super-resolution precision by near-field nonlinear coupling of a digitally coding needle meta-chip
Huajie Liang, Hongxin Zeng, Tianchi Zhou, Hanyu Zhao, Shaokang Gu, Lin Zou, Tao Jiang, Lan Wang, Feng Lan, Shixiong Liang, Zhihong Feng, Ziqiang Yang, and Yaxin Zhang
Achieving ultra-precise wide-range terahertz (THz) phase modulation has been a long-standing challenge due to the short wavelength and sensitive phase of THz waves. This paper proposes a new ultra-high precision phase control method employing a digitally coding needle meta-chip embedded in a waveguide. The needle tips can effectively couple THz waves via the charge aggregation effect. By controlling the Schottky diodes with coding voltages, the charge on each meta-structure part can be tuned to form strong or weak resonances, producing phase shifts. Crucially, the massive charge accumulation and the sub-λ/10 distance between needle tips lead to near-field coupling among multiple tips. Therefore, modulation of the charge at each tip by multichannel coding voltages enables combined resonance tuning of THz waves, yielding a nonlinear phase superposition. Here, a meta-chip containing 8 needle meta-structure units is demonstrated, which breaks through the precision limitation of independent units and realizes super-resolution precision phase modulation similar to super-resolution imaging. In the 213–227 GHz band, we achieve a phase shift exceeding 180° with 11.25° accuracy, and a phase shift of over 170° with an accuracy of 3°. This super-resolution phase modulation strategy provides a new idea for future high-precision applications of THz integrated systems. Achieving ultra-precise wide-range terahertz (THz) phase modulation has been a long-standing challenge due to the short wavelength and sensitive phase of THz waves. This paper proposes a new ultra-high precision phase control method employing a digitally coding needle meta-chip embedded in a waveguide. The needle tips can effectively couple THz waves via the charge aggregation effect. By controlling the Schottky diodes with coding voltages, the charge on each meta-structure part can be tuned to form strong or weak resonances, producing phase shifts. Crucially, the massive charge accumulation and the sub-λ/10 distance between needle tips lead to near-field coupling among multiple tips. Therefore, modulation of the charge at each tip by multichannel coding voltages enables combined resonance tuning of THz waves, yielding a nonlinear phase superposition. Here, a meta-chip containing 8 needle meta-structure units is demonstrated, which breaks through the precision limitation of independent units and realizes super-resolution precision phase modulation similar to super-resolution imaging. In the 213–227 GHz band, we achieve a phase shift exceeding 180° with 11.25° accuracy, and a phase shift of over 170° with an accuracy of 3°. This super-resolution phase modulation strategy provides a new idea for future high-precision applications of THz integrated systems.
Photonics Research
- Publication Date: Aug. 19, 2024
- Vol. 12, Issue 9, 1868 (2024)
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