Pub Date : 2024-07-17DOI: 10.1038/s41377-024-01517-y
Seongjin Park, Jaeyeon Yu, Gerhard Boehm, Mikhail A. Belkin, Jongwon Lee
Nonlinear intersubband polaritonic metasurfaces, which integrate giant nonlinear responses derived from intersubband transitions of multiple quantum wells (MQWs) with plasmonic nanoresonators, not only facilitate efficient frequency conversion at pump intensities on the order of few tens of kW cm-2 but also enable electrical modulation of nonlinear responses at the individual meta-atom level and dynamic beam manipulation. The electrical modulation characteristics of the magnitude and phase of the nonlinear optical response are realized through Stark tuning of the resonant intersubband nonlinearity. In this study, we report, for the first time, experimental implementations of electrical modulation characteristics of mid-infrared third-harmonic generation (THG) using an intersubband polaritonic metasurface based on MQW with electrically tunable third-order nonlinear response. Experimentally, we achieved a 450% modulation depth of the THG signal, 86% suppression of zero-order THG diffraction tuning based on local phase tuning exceeding 180 degrees, and THG beam steering using phase gradients. Our work proposes a new route for electrically tunable flat nonlinear optical elements with versatile functionalities.
{"title":"Electrically tunable third-harmonic generation using intersubband polaritonic metasurfaces","authors":"Seongjin Park, Jaeyeon Yu, Gerhard Boehm, Mikhail A. Belkin, Jongwon Lee","doi":"10.1038/s41377-024-01517-y","DOIUrl":"https://doi.org/10.1038/s41377-024-01517-y","url":null,"abstract":"<p>Nonlinear intersubband polaritonic metasurfaces, which integrate giant nonlinear responses derived from intersubband transitions of multiple quantum wells (MQWs) with plasmonic nanoresonators, not only facilitate efficient frequency conversion at pump intensities on the order of few tens of kW cm<sup>-2</sup> but also enable electrical modulation of nonlinear responses at the individual meta-atom level and dynamic beam manipulation. The electrical modulation characteristics of the magnitude and phase of the nonlinear optical response are realized through Stark tuning of the resonant intersubband nonlinearity. In this study, we report, for the first time, experimental implementations of electrical modulation characteristics of mid-infrared third-harmonic generation (THG) using an intersubband polaritonic metasurface based on MQW with electrically tunable third-order nonlinear response. Experimentally, we achieved a 450% modulation depth of the THG signal, 86% suppression of zero-order THG diffraction tuning based on local phase tuning exceeding 180 degrees, and THG beam steering using phase gradients. Our work proposes a new route for electrically tunable flat nonlinear optical elements with versatile functionalities.</p>","PeriodicalId":18069,"journal":{"name":"Light-Science & Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141631293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Laser pulse multiplication from an optical gain medium has shown great potential in miniaturizing integrated optoelectronic devices. Perovskite multiple quantum wells (MQWs) structures have recently been recognized as an effective gain media capable of doubling laser pulses that do not rely on external optical equipment. Although the light amplifications enabled with pulse doubling are reported based on the perovskite MQWs thin films, the micro-nanolasers possessed a specific cavity for laser pulse multiplication and their corresponding intrinsic laser dynamics are still inadequate. Herein, a single-mode double-pulsed nanolaser from self-assembled perovskite MQWs nanowires is realized, exhibiting a pulse duration of 28 ps and pulse interval of 22 ps based on single femtosecond laser pulse excitation. It is established that the continuous energy building up within a certain timescale is essential for the multiple population inversion in the gain medium, which arises from the slowing carrier localization process owning to the stronger exciton–phonon coupling in the smaller-n QWs. Therefore, the double-pulsed lasing is achieved from one fast energy funnel process from the adjacent small-n QWs to gain active region and another slow process from the spatially separated ones. This report may shed new light on the intrinsic energy relaxation mechanism and boost the further development of perovskite multiple-pulse lasers.
来自光学增益介质的激光脉冲倍增技术在集成光电设备微型化方面显示出巨大的潜力。最近,人们认识到包晶多量子阱(MQWs)结构是一种有效的增益介质,能够使激光脉冲倍增,而无需依赖外部光学设备。虽然基于包晶多量子阱薄膜实现脉冲倍增的光放大技术已有报道,但拥有特定腔体用于激光脉冲倍增的微型激光器及其相应的内在激光动力学仍然不足。本文利用自组装的包晶MQWs纳米线实现了单模双脉冲纳米激光器,在单飞秒激光脉冲激励下,脉冲持续时间为28 ps,脉冲间隔为22 ps。研究证实,在一定时间尺度内持续积累能量对于增益介质中的多重种群反转至关重要,而增益介质中的多重种群反转则源于小n QW 中激子-声子耦合较强导致载流子定位过程减慢。因此,从相邻的小 n QW 到增益有源区的一个快速能量漏斗过程和从空间上分离的小 n QW 到增益有源区的另一个慢速过程实现了双脉冲激光。该报告可能会为本征能量弛豫机制带来新的启示,并推动包晶多脉冲激光器的进一步发展。
{"title":"Pulse-doubling perovskite nanowire lasers enabled by phonon-assisted multistep energy funneling","authors":"Chunhu Zhao, Jia Guo, Jiahua Tao, Junhao Chu, Shaoqiang Chen, Guichuan Xing","doi":"10.1038/s41377-024-01494-2","DOIUrl":"https://doi.org/10.1038/s41377-024-01494-2","url":null,"abstract":"<p>Laser pulse multiplication from an optical gain medium has shown great potential in miniaturizing integrated optoelectronic devices. Perovskite multiple quantum wells (MQWs) structures have recently been recognized as an effective gain media capable of doubling laser pulses that do not rely on external optical equipment. Although the light amplifications enabled with pulse doubling are reported based on the perovskite MQWs thin films, the micro-nanolasers possessed a specific cavity for laser pulse multiplication and their corresponding intrinsic laser dynamics are still inadequate. Herein, a single-mode double-pulsed nanolaser from self-assembled perovskite MQWs nanowires is realized, exhibiting a pulse duration of 28 ps and pulse interval of 22 ps based on single femtosecond laser pulse excitation. It is established that the continuous energy building up within a certain timescale is essential for the multiple population inversion in the gain medium, which arises from the slowing carrier localization process owning to the stronger exciton–phonon coupling in the smaller-<i>n</i> QWs. Therefore, the double-pulsed lasing is achieved from one fast energy funnel process from the adjacent small-<i>n</i> QWs to gain active region and another slow process from the spatially separated ones. This report may shed new light on the intrinsic energy relaxation mechanism and boost the further development of perovskite multiple-pulse lasers.</p>","PeriodicalId":18069,"journal":{"name":"Light-Science & Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141631292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-16DOI: 10.1038/s41377-024-01514-1
Zan Tang, Tian Chen, Xing Tang, Xiangdong Zhang
The robust operation of quantum entanglement states is crucial for applications in quantum information, computing, and communications1,2,3. However, it has always been a great challenge to complete such a task because of decoherence and disorder. Here, we propose theoretically and demonstrate experimentally an effective scheme to realize robust operation of quantum entanglement states by designing quadruple degeneracy exceptional points. By encircling the exceptional points on two overlapping Riemann energy surfaces, we have realized a chiral switch for entangled states with high fidelity. Owing to the topological protection conferred by the Riemann surface structure, this switching of chirality exhibits strong robustness against perturbations in the encircling path. Furthermore, we have experimentally validated such a scheme on a quantum walk platform. Our work opens up a new way for the application of non-Hermitian physics in the field of quantum information.
{"title":"Topologically protected entanglement switching around exceptional points","authors":"Zan Tang, Tian Chen, Xing Tang, Xiangdong Zhang","doi":"10.1038/s41377-024-01514-1","DOIUrl":"https://doi.org/10.1038/s41377-024-01514-1","url":null,"abstract":"<p>The robust operation of quantum entanglement states is crucial for applications in quantum information, computing, and communications<sup>1,2,3</sup>. However, it has always been a great challenge to complete such a task because of decoherence and disorder. Here, we propose theoretically and demonstrate experimentally an effective scheme to realize robust operation of quantum entanglement states by designing quadruple degeneracy exceptional points. By encircling the exceptional points on two overlapping Riemann energy surfaces, we have realized a chiral switch for entangled states with high fidelity. Owing to the topological protection conferred by the Riemann surface structure, this switching of chirality exhibits strong robustness against perturbations in the encircling path. Furthermore, we have experimentally validated such a scheme on a quantum walk platform. Our work opens up a new way for the application of non-Hermitian physics in the field of quantum information.</p>","PeriodicalId":18069,"journal":{"name":"Light-Science & Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141624774","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-15DOI: 10.1038/s41377-024-01507-0
Xilin Ma, Yuhua Wang, Takatoshi Seto
An immature understanding of the mechanisms of persistent luminescence (PersL) has hindered the development of new persistent luminescent materials (PersLMs) with increased brightness. In this regard, in-situ direct current (DC) electric field measurements were conducted on a layered structure composed of the SrAl2O4:Eu2+,Dy3+ phosphor, and an electrode. In this study, the photoluminescence (PL) and afterglow properties were investigated with respect to voltage by analyzing the current signal and thermoluminescence (TL) spectroscopy. The intensity of PersL increased due to a novel phenomenon known as “external electric field stimulated enhancement of initial brightness of afterglow”. This dynamic process was illustrated via the use of a rate equation approach, where the electrons trapped by the ultra-shallow trap at 0.022 eV could be transferred through the conduction band during long afterglow. The afterglow intensity could reach 0.538 cd m−2 at a 6 V electric voltage. The design of an electric field stimulation technique enables the enhancement of the intensity of PersLMs and provides a new perspective for exploring the fundamental mechanics of certain established PersLMs.
对持久发光(PersL)机理的不成熟认识阻碍了具有更高亮度的新型持久发光材料(PersLMs)的开发。为此,我们对由 SrAl2O4:Eu2+,Dy3+ 荧光粉和电极组成的层状结构进行了原位直流(DC)电场测量。在这项研究中,通过分析电流信号和热释光(TL)光谱,研究了光致发光(PL)和余辉特性与电压的关系。由于一种被称为 "外部电场刺激增强余辉初始亮度 "的新现象,PersL 的强度增加了。这一动态过程是通过使用速率方程的方法来说明的,即被 0.022 eV 的超浅阱捕获的电子可在长余辉期间通过传导带转移。在 6 V 的电压下,余辉强度可达 0.538 cd m-2。电场刺激技术的设计能够增强 PersLM 的强度,并为探索某些已建立的 PersLM 的基本力学提供了新的视角。
{"title":"Electrical stimulation for brighter persistent luminescence","authors":"Xilin Ma, Yuhua Wang, Takatoshi Seto","doi":"10.1038/s41377-024-01507-0","DOIUrl":"https://doi.org/10.1038/s41377-024-01507-0","url":null,"abstract":"<p>An immature understanding of the mechanisms of persistent luminescence (PersL) has hindered the development of new persistent luminescent materials (PersLMs) with increased brightness. In this regard, in-situ direct current (DC) electric field measurements were conducted on a layered structure composed of the SrAl<sub>2</sub>O<sub>4</sub>:Eu<sup>2+</sup>,Dy<sup>3+</sup> phosphor, and an electrode. In this study, the photoluminescence (PL) and afterglow properties were investigated with respect to voltage by analyzing the current signal and thermoluminescence (TL) spectroscopy. The intensity of PersL increased due to a novel phenomenon known as “external electric field stimulated enhancement of initial brightness of afterglow”. This dynamic process was illustrated via the use of a rate equation approach, where the electrons trapped by the ultra-shallow trap at 0.022 eV could be transferred through the conduction band during long afterglow. The afterglow intensity could reach 0.538 cd m<sup>−2</sup> at a 6 V electric voltage. The design of an electric field stimulation technique enables the enhancement of the intensity of PersLMs and provides a new perspective for exploring the fundamental mechanics of certain established PersLMs.</p>","PeriodicalId":18069,"journal":{"name":"Light-Science & Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141618369","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-15DOI: 10.1038/s41377-023-01343-8
Hui Wang, Cun Yu
The sense of light is the first sensation the human body develops. The importance of light is self-evident. However, we all know that the light we can see and perceive covers only a small section of the spectrum. Today, for Light People, we feature a researcher who is committed to exploring different spectral bands of light ranging from deep ultraviolet to terahertz waves and working on quantum semiconductor technology, Prof. Manijeh Razeghi of the Northwestern University in the United States. Known for her quick thinking and witty remarks, Prof. Razeghi is passionate about life and always kind to others. As a scientist, she does not limit her research to a single focus, instead, she works on the entire process from material selection, device design, processing, and manufacturing, all the way to product application. She has a strong passion for education, a commitment unwavered by fame or fortune. For her students, she is both a reliable source of knowledge and a motherly figure with a caring heart. She firmly believes that all things in nature can give her energy and inspiration. In science, she is a true “pioneer” in research and a “miner” of scientific discoveries. She advises young scientists to enjoy and love what they do, and turn their research into their hobby. As a female scientist, she calls on all women to realize their true value and potential. Next, let’s hear from Professor Manijeh Razeghi, a true star who radiates energy and light.
{"title":"Light People: Professor Manijeh Razeghi","authors":"Hui Wang, Cun Yu","doi":"10.1038/s41377-023-01343-8","DOIUrl":"https://doi.org/10.1038/s41377-023-01343-8","url":null,"abstract":"<p>The sense of light is the first sensation the human body develops. The importance of light is self-evident. However, we all know that the light we can see and perceive covers only a small section of the spectrum. Today, for Light People, we feature a researcher who is committed to exploring different spectral bands of light ranging from deep ultraviolet to terahertz waves and working on quantum semiconductor technology, Prof. Manijeh Razeghi of the Northwestern University in the United States. Known for her quick thinking and witty remarks, Prof. Razeghi is passionate about life and always kind to others. As a scientist, she does not limit her research to a single focus, instead, she works on the entire process from material selection, device design, processing, and manufacturing, all the way to product application. She has a strong passion for education, a commitment unwavered by fame or fortune. For her students, she is both a reliable source of knowledge and a motherly figure with a caring heart. She firmly believes that all things in nature can give her energy and inspiration. In science, she is a true “pioneer” in research and a “miner” of scientific discoveries. She advises young scientists to enjoy and love what they do, and turn their research into their hobby. As a female scientist, she calls on all women to realize their true value and potential. Next, let’s hear from Professor Manijeh Razeghi, a true star who radiates energy and light.</p>","PeriodicalId":18069,"journal":{"name":"Light-Science & Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141618368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-10DOI: 10.1038/s41377-024-01511-4
Sheng Gao, Hang Chen, Yichen Wang, Zhengyang Duan, Haiou Zhang, Zhi Sun, Yuan Shen, Xing Lin
Wireless sensing of the wave propagation direction from radio sources lays the foundation for communication, radar, navigation, etc. However, the existing signal processing paradigm for the direction of arrival estimation requires the radio frequency electronic circuit to demodulate and sample the multichannel baseband signals followed by a complicated computing process, which places the fundamental limit on its sensing speed and energy efficiency. Here, we propose the super-resolution diffractive neural networks (S-DNN) to process electromagnetic (EM) waves directly for the DOA estimation at the speed of light. The multilayer meta-structures of S-DNN generate super-oscillatory angular responses in local angular regions that can perform the all-optical DOA estimation with angular resolutions beyond the diffraction limit. The spatial-temporal multiplexing of passive and reconfigurable S-DNNs is utilized to achieve high-resolution DOA estimation over a wide field of view. The S-DNN is validated for the DOA estimation of multiple radio sources over 5 GHz frequency bandwidth with estimation latency over two to four orders of magnitude lower than the state-of-the-art commercial devices in principle. The results achieve the angular resolution over an order of magnitude, experimentally demonstrated with four times, higher than diffraction-limited resolution. We also apply S-DNN’s edge computing capability, assisted by reconfigurable intelligent surfaces, for extremely low-latency integrated sensing and communication with low power consumption. Our work is a significant step towards utilizing photonic computing processors to facilitate various wireless sensing and communication tasks with advantages in both computing paradigms and performance over electronic computing.
对无线电波传播方向的无线传感为通信、雷达、导航等奠定了基础。然而,现有的到达方向估计信号处理范式需要射频电子电路对多通道基带信号进行解调和采样,然后进行复杂的计算处理,这从根本上限制了其传感速度和能效。在此,我们提出了超分辨率衍射神经网络(S-DNN),以光速直接处理电磁波(EM),进行 DOA 估计。S-DNN 的多层元结构可在局部角度区域产生超振荡角度响应,从而以超越衍射极限的角度分辨率执行全光 DOA 估计。利用无源和可重构 S-DNN 的时空复用技术,可在宽视场范围内实现高分辨率 DOA 估计。S-DNN 在 5 GHz 频率带宽上对多个无线电信号源的 DOA 估计进行了验证,其估计延迟原则上比最先进的商业设备低 2 到 4 个数量级。结果实现了超过一个数量级的角度分辨率,实验证明比衍射极限分辨率高出四倍。我们还应用了 S-DNN 的边缘计算能力,在可重构智能表面的辅助下,以低功耗实现了极低延迟的集成传感和通信。我们的工作是朝着利用光子计算处理器促进各种无线传感和通信任务迈出的重要一步,在计算模式和性能方面都比电子计算有优势。
{"title":"Super-resolution diffractive neural network for all-optical direction of arrival estimation beyond diffraction limits","authors":"Sheng Gao, Hang Chen, Yichen Wang, Zhengyang Duan, Haiou Zhang, Zhi Sun, Yuan Shen, Xing Lin","doi":"10.1038/s41377-024-01511-4","DOIUrl":"https://doi.org/10.1038/s41377-024-01511-4","url":null,"abstract":"<p>Wireless sensing of the wave propagation direction from radio sources lays the foundation for communication, radar, navigation, etc. However, the existing signal processing paradigm for the direction of arrival estimation requires the radio frequency electronic circuit to demodulate and sample the multichannel baseband signals followed by a complicated computing process, which places the fundamental limit on its sensing speed and energy efficiency. Here, we propose the super-resolution diffractive neural networks (S-DNN) to process electromagnetic (EM) waves directly for the DOA estimation at the speed of light. The multilayer meta-structures of S-DNN generate super-oscillatory angular responses in local angular regions that can perform the all-optical DOA estimation with angular resolutions beyond the diffraction limit. The spatial-temporal multiplexing of passive and reconfigurable S-DNNs is utilized to achieve high-resolution DOA estimation over a wide field of view. The S-DNN is validated for the DOA estimation of multiple radio sources over 5 GHz frequency bandwidth with estimation latency over two to four orders of magnitude lower than the state-of-the-art commercial devices in principle. The results achieve the angular resolution over an order of magnitude, experimentally demonstrated with four times, higher than diffraction-limited resolution. We also apply S-DNN’s edge computing capability, assisted by reconfigurable intelligent surfaces, for extremely low-latency integrated sensing and communication with low power consumption. Our work is a significant step towards utilizing photonic computing processors to facilitate various wireless sensing and communication tasks with advantages in both computing paradigms and performance over electronic computing.</p>","PeriodicalId":18069,"journal":{"name":"Light-Science & Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141566294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-10DOI: 10.1038/s41377-024-01447-9
Alex J. Vernon, Sebastian Golat, Claire Rigouzzo, Eugene A. Lim, Francisco J. Rodríguez-Fortuño
Light carries intrinsic spin angular momentum (SAM) when the electric or magnetic field vector rotates over time. A familiar vector equation calculates the direction of light’s SAM density using the right-hand rule with reference to the electric and magnetic polarisation ellipses. Using Maxwell’s equations, this vector equation can be decomposed into a sum of two distinct terms, akin to the well-known Poynting vector decomposition into orbital and spin currents. We present the first general study of this spin decomposition, showing that the two terms, which we call canonical and Poynting spin, are chiral analogies to the canonical and spin momenta of light in its interaction with matter. Like canonical momentum, canonical spin is directly measurable. Both canonical and Poynting spin incorporate spatial variation of the electric and magnetic fields and are influenced by optical vortices. The decomposition allows us to show that a linearly polarised vortex beam, which has no total SAM, can nevertheless exert longitudinal chiral pressure due to equal and opposite canonical and Poynting spins.
当电场或磁场矢量随时间旋转时,光会携带固有的自旋角动量(SAM)。我们熟悉的矢量方程利用右手定则,参照电偏振椭圆和磁偏振椭圆计算光的自旋角动量密度方向。利用麦克斯韦方程,这个矢量方程可以分解为两个不同项的总和,类似于著名的波因定矢量分解为轨道电流和自旋电流。我们首次对这种自旋分解进行了一般性研究,表明这两个项(我们称之为规范自旋和波因廷自旋)是光在与物质相互作用时的规范动量和自旋矩的手性类比。与规范动量一样,规范自旋也是可以直接测量的。规范自旋和波因廷自旋都包含电场和磁场的空间变化,并受光学涡旋的影响。通过分解,我们可以证明,没有总 SAM 的线性偏振涡旋光束,也会因等量且相反的 Canonical 自旋和 Poynting 自旋而产生纵向手性压力。
{"title":"A decomposition of light’s spin angular momentum density","authors":"Alex J. Vernon, Sebastian Golat, Claire Rigouzzo, Eugene A. Lim, Francisco J. Rodríguez-Fortuño","doi":"10.1038/s41377-024-01447-9","DOIUrl":"https://doi.org/10.1038/s41377-024-01447-9","url":null,"abstract":"<p>Light carries intrinsic spin angular momentum (SAM) when the electric or magnetic field vector rotates over time. A familiar vector equation calculates the direction of light’s SAM density using the right-hand rule with reference to the electric and magnetic polarisation ellipses. Using Maxwell’s equations, this vector equation can be decomposed into a sum of two distinct terms, akin to the well-known Poynting vector decomposition into orbital and spin currents. We present the first general study of this spin decomposition, showing that the two terms, which we call canonical and Poynting spin, are chiral analogies to the canonical and spin momenta of light in its interaction with matter. Like canonical momentum, canonical spin is directly measurable. Both canonical and Poynting spin incorporate spatial variation of the electric and magnetic fields and are influenced by optical vortices. The decomposition allows us to show that a linearly polarised vortex beam, which has no total SAM, can nevertheless exert longitudinal chiral pressure due to equal and opposite canonical and Poynting spins.</p>","PeriodicalId":18069,"journal":{"name":"Light-Science & Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141566293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-09DOI: 10.1038/s41377-024-01446-w
Xiaomeng Sui, Zehao He, Daping Chu, Liangcai Cao
Computer-generated holography is a promising technique that modulates user-defined wavefronts with digital holograms. Computing appropriate holograms with faithful reconstructions is not only a problem closely related to the fundamental basis of holography but also a long-standing challenge for researchers in general fields of optics. Finding the exact solution of a desired hologram to reconstruct an accurate target object constitutes an ill-posed inverse problem. The general practice of single-diffraction computation for synthesizing holograms can only provide an approximate answer, which is subject to limitations in numerical implementation. Various non-convex optimization algorithms are thus designed to seek an optimal solution by introducing different constraints, frameworks, and initializations. Herein, we overview the optimization algorithms applied to computer-generated holography, incorporating principles of hologram synthesis based on alternative projections and gradient descent methods. This is aimed to provide an underlying basis for optimized hologram generation, as well as insights into the cutting-edge developments of this rapidly evolving field for potential applications in virtual reality, augmented reality, head-up display, data encryption, laser fabrication, and metasurface design.
{"title":"Non-convex optimization for inverse problem solving in computer-generated holography","authors":"Xiaomeng Sui, Zehao He, Daping Chu, Liangcai Cao","doi":"10.1038/s41377-024-01446-w","DOIUrl":"https://doi.org/10.1038/s41377-024-01446-w","url":null,"abstract":"<p>Computer-generated holography is a promising technique that modulates user-defined wavefronts with digital holograms. Computing appropriate holograms with faithful reconstructions is not only a problem closely related to the fundamental basis of holography but also a long-standing challenge for researchers in general fields of optics. Finding the exact solution of a desired hologram to reconstruct an accurate target object constitutes an ill-posed inverse problem. The general practice of single-diffraction computation for synthesizing holograms can only provide an approximate answer, which is subject to limitations in numerical implementation. Various non-convex optimization algorithms are thus designed to seek an optimal solution by introducing different constraints, frameworks, and initializations. Herein, we overview the optimization algorithms applied to computer-generated holography, incorporating principles of hologram synthesis based on alternative projections and gradient descent methods. This is aimed to provide an underlying basis for optimized hologram generation, as well as insights into the cutting-edge developments of this rapidly evolving field for potential applications in virtual reality, augmented reality, head-up display, data encryption, laser fabrication, and metasurface design.</p>","PeriodicalId":18069,"journal":{"name":"Light-Science & Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141561320","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-09DOI: 10.1038/s41377-024-01480-8
Xuening Cao, Hao Yang, Zu-Lei Wu, Bei-Bei Li
Ultrasound sensors play an important role in biomedical imaging, industrial nondestructive inspection, etc. Traditional ultrasound sensors that use piezoelectric transducers face limitations in sensitivity and spatial resolution when miniaturized, with typical sizes at the millimeter to centimeter scale. To overcome these challenges, optical ultrasound sensors have emerged as a promising alternative, offering both high sensitivity and spatial resolution. In particular, ultrasound sensors utilizing high-quality factor (Q) optical microcavities have achieved unprecedented performance in terms of sensitivity and bandwidth, while also enabling mass production on silicon chips. In this review, we focus on recent advances in ultrasound sensing applications using three types of optical microcavities: Fabry-Perot cavities, π-phase-shifted Bragg gratings, and whispering gallery mode microcavities. We provide an overview of the ultrasound sensing mechanisms employed by these microcavities and discuss the key parameters for optimizing ultrasound sensors. Furthermore, we survey recent advances in ultrasound sensing using these microcavity-based approaches, highlighting their applications in diverse detection scenarios, such as photoacoustic imaging, ranging, and particle detection. The goal of this review is to provide a comprehensive understanding of the latest advances in ultrasound sensing with optical microcavities and their potential for future development in high-performance ultrasound imaging and sensing technologies.
{"title":"Ultrasound sensing with optical microcavities","authors":"Xuening Cao, Hao Yang, Zu-Lei Wu, Bei-Bei Li","doi":"10.1038/s41377-024-01480-8","DOIUrl":"https://doi.org/10.1038/s41377-024-01480-8","url":null,"abstract":"<p>Ultrasound sensors play an important role in biomedical imaging, industrial nondestructive inspection, etc. Traditional ultrasound sensors that use piezoelectric transducers face limitations in sensitivity and spatial resolution when miniaturized, with typical sizes at the millimeter to centimeter scale. To overcome these challenges, optical ultrasound sensors have emerged as a promising alternative, offering both high sensitivity and spatial resolution. In particular, ultrasound sensors utilizing high-quality factor (<i>Q</i>) optical microcavities have achieved unprecedented performance in terms of sensitivity and bandwidth, while also enabling mass production on silicon chips. In this review, we focus on recent advances in ultrasound sensing applications using three types of optical microcavities: Fabry-Perot cavities, π-phase-shifted Bragg gratings, and whispering gallery mode microcavities. We provide an overview of the ultrasound sensing mechanisms employed by these microcavities and discuss the key parameters for optimizing ultrasound sensors. Furthermore, we survey recent advances in ultrasound sensing using these microcavity-based approaches, highlighting their applications in diverse detection scenarios, such as photoacoustic imaging, ranging, and particle detection. The goal of this review is to provide a comprehensive understanding of the latest advances in ultrasound sensing with optical microcavities and their potential for future development in high-performance ultrasound imaging and sensing technologies.</p>","PeriodicalId":18069,"journal":{"name":"Light-Science & Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141561491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-08DOI: 10.1038/s41377-024-01491-5
Magdalena Grzeszczyk, Kristina Vaklinova, Kenji Watanabe, Takashi Taniguchi, Konstantin S. Novoselov, Maciej Koperski
Defect centers in wide-band-gap crystals have garnered interest for their potential in applications among optoelectronic and sensor technologies. However, defects embedded in highly insulating crystals, like diamond, silicon carbide, or aluminum oxide, have been notoriously difficult to excite electrically due to their large internal resistance. To address this challenge, we realized a new paradigm of exciting defects in vertical tunneling junctions based on carbon centers in hexagonal boron nitride (hBN). The rational design of the devices via van der Waals technology enabled us to raise and control optical processes related to defect-to-band and intradefect electroluminescence. The fundamental understanding of the tunneling events was based on the transfer of the electronic wave function amplitude between resonant defect states in hBN to the metallic state in graphene, which leads to dramatic changes in the characteristics of electrons due to different band structures of constituent materials. In our devices, the decay of electrons via tunneling pathways competed with radiative recombination, resulting in an unprecedented degree of tuneability of carrier dynamics due to the significant sensitivity of the characteristic tunneling times on the thickness and structure of the barrier. This enabled us to achieve a high-efficiency electrical excitation of intradefect transitions, exceeding by several orders of magnitude the efficiency of optical excitation in the sub-band-gap regime. This work represents a significant advancement towards a universal and scalable platform for electrically driven devices utilizing defect centers in wide-band-gap crystals with properties modulated via activation of different tunneling mechanisms at a level of device engineering.
{"title":"Electroluminescence from pure resonant states in hBN-based vertical tunneling junctions","authors":"Magdalena Grzeszczyk, Kristina Vaklinova, Kenji Watanabe, Takashi Taniguchi, Konstantin S. Novoselov, Maciej Koperski","doi":"10.1038/s41377-024-01491-5","DOIUrl":"https://doi.org/10.1038/s41377-024-01491-5","url":null,"abstract":"<p>Defect centers in wide-band-gap crystals have garnered interest for their potential in applications among optoelectronic and sensor technologies. However, defects embedded in highly insulating crystals, like diamond, silicon carbide, or aluminum oxide, have been notoriously difficult to excite electrically due to their large internal resistance. To address this challenge, we realized a new paradigm of exciting defects in vertical tunneling junctions based on carbon centers in hexagonal boron nitride (hBN). The rational design of the devices via van der Waals technology enabled us to raise and control optical processes related to defect-to-band and intradefect electroluminescence. The fundamental understanding of the tunneling events was based on the transfer of the electronic wave function amplitude between resonant defect states in hBN to the metallic state in graphene, which leads to dramatic changes in the characteristics of electrons due to different band structures of constituent materials. In our devices, the decay of electrons via tunneling pathways competed with radiative recombination, resulting in an unprecedented degree of tuneability of carrier dynamics due to the significant sensitivity of the characteristic tunneling times on the thickness and structure of the barrier. This enabled us to achieve a high-efficiency electrical excitation of intradefect transitions, exceeding by several orders of magnitude the efficiency of optical excitation in the sub-band-gap regime. This work represents a significant advancement towards a universal and scalable platform for electrically driven devices utilizing defect centers in wide-band-gap crystals with properties modulated via activation of different tunneling mechanisms at a level of device engineering.</p>","PeriodicalId":18069,"journal":{"name":"Light-Science & Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2024-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141557183","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}