Pub Date : 2024-08-01DOI: 10.1038/s44310-024-00017-6
Clément Majorel, Amir Loucif, Emil Marinov, Renato Juliano Martins, Adelin Patoux, Pierre-Marie Coulon, Virginie Brandli, Michel Antolovic, Claudio Bruschini, Edoardo Charbon, Patrice Genevet
The eyes of arthropods, such as those found in bees and dragonflies, are sophisticated 3D vision tools that are composed of an array of directional microlenses. Despite the attempts in achieving artificial panoramic vision by mimicking arthropod eyes with curved microlens arrays, a wealth of issues related to optical aberrations and fabrication complexity have been reported. However, achieving such a wide-angle 3D imaging is becoming essential nowadays for autonomous robotic systems, yet most of the available solutions fail to simultaneously meet the requirements in terms of field of view, frame rate, or resistance to mechanical wear. Metasurfaces, or planar nanostructured optical surfaces, can overcome the limitation of curved optics, achieving panoramic vision and selective focusing of the light on a plane. On-chip vertical integration of directional metalenses on the top of a planar array of detectors enables a powerful bio-inspired LiDAR that is capable of 3D imaging over a wide field of view without using any mechanical parts. Implementation of metasurface arrays on imaging sensors is shown to have relevant industrial applications in 3D sensing that goes beyond the basic usage of metalenses for imaging.
{"title":"Bio-inspired flat optics for directional 3D light detection and ranging","authors":"Clément Majorel, Amir Loucif, Emil Marinov, Renato Juliano Martins, Adelin Patoux, Pierre-Marie Coulon, Virginie Brandli, Michel Antolovic, Claudio Bruschini, Edoardo Charbon, Patrice Genevet","doi":"10.1038/s44310-024-00017-6","DOIUrl":"10.1038/s44310-024-00017-6","url":null,"abstract":"The eyes of arthropods, such as those found in bees and dragonflies, are sophisticated 3D vision tools that are composed of an array of directional microlenses. Despite the attempts in achieving artificial panoramic vision by mimicking arthropod eyes with curved microlens arrays, a wealth of issues related to optical aberrations and fabrication complexity have been reported. However, achieving such a wide-angle 3D imaging is becoming essential nowadays for autonomous robotic systems, yet most of the available solutions fail to simultaneously meet the requirements in terms of field of view, frame rate, or resistance to mechanical wear. Metasurfaces, or planar nanostructured optical surfaces, can overcome the limitation of curved optics, achieving panoramic vision and selective focusing of the light on a plane. On-chip vertical integration of directional metalenses on the top of a planar array of detectors enables a powerful bio-inspired LiDAR that is capable of 3D imaging over a wide field of view without using any mechanical parts. Implementation of metasurface arrays on imaging sensors is shown to have relevant industrial applications in 3D sensing that goes beyond the basic usage of metalenses for imaging.","PeriodicalId":501711,"journal":{"name":"npj Nanophotonics","volume":" ","pages":"1-10"},"PeriodicalIF":0.0,"publicationDate":"2024-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44310-024-00017-6.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141968470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-17DOI: 10.1038/s44310-024-00019-4
Yunxiu Ma, Gang Zhong, Zhigao Dai, Qingdong Ou
In-plane hyperbolic phonon polaritons (HPhPs) are phonon-mediated hybrid electromagnetic modes, particularly in two-dimensional (2D) van der Waals (vdW) crystals, which have attracted increasing attention because of their peculiar optical properties and promising nanophotonic applications. Here, we review the most recent advances in in-plane HPhPs in terms of materials, optical properties and nanophotonic devices. We begin with a survey of recently discovered in-plane anisotropic vdW materials and bulk crystals that naturally exhibit in-plane HPhPs. The fundamental properties of HPhPs in these anisotropic materials are then discussed, focusing on propagation directionality such as direction rotation, unidirectional excitation, canalization, negative reflection, and negative refraction. Finally, we discuss the present applications of in-plane HPhPs in nanophotonic devices and offer a perspective on future developments of in-plane HPhPs towards nanophotonic chips.
{"title":"In-plane hyperbolic phonon polaritons: materials, properties, and nanophotonic devices","authors":"Yunxiu Ma, Gang Zhong, Zhigao Dai, Qingdong Ou","doi":"10.1038/s44310-024-00019-4","DOIUrl":"10.1038/s44310-024-00019-4","url":null,"abstract":"In-plane hyperbolic phonon polaritons (HPhPs) are phonon-mediated hybrid electromagnetic modes, particularly in two-dimensional (2D) van der Waals (vdW) crystals, which have attracted increasing attention because of their peculiar optical properties and promising nanophotonic applications. Here, we review the most recent advances in in-plane HPhPs in terms of materials, optical properties and nanophotonic devices. We begin with a survey of recently discovered in-plane anisotropic vdW materials and bulk crystals that naturally exhibit in-plane HPhPs. The fundamental properties of HPhPs in these anisotropic materials are then discussed, focusing on propagation directionality such as direction rotation, unidirectional excitation, canalization, negative reflection, and negative refraction. Finally, we discuss the present applications of in-plane HPhPs in nanophotonic devices and offer a perspective on future developments of in-plane HPhPs towards nanophotonic chips.","PeriodicalId":501711,"journal":{"name":"npj Nanophotonics","volume":" ","pages":"1-14"},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44310-024-00019-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141730380","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-17DOI: 10.1038/s44310-024-00030-9
Xucheng Zhang, Chunxue Wang, Zhibo Cheng, Congyu Hu, Xingchen Ji, Yikai Su
Recent developments in resonator-based Kerr frequency combs promise excellent applications in a wide range of fields such as biosensing, spectroscopy, optical communications, light detection and ranging (LiDAR), frequency synthesis, astronomical detection, and quantum optics. A key figure of merit (FOM) for Kerr frequency combs is the pump-to-comb conversion efficiency, which is critical for applications requiring sufficient comb power and low power consumption. In this review, we first discuss the limited conversion efficiency of dissipative Kerr soliton in an anomalous dispersion microresonator based on its underlying physical characteristics. And then, we summarize the recent advances in Kerr frequency combs with high conversion efficiencies in both anomalous and normal dispersion regimes. We classify them according to various soliton states, excitation methods as well as novel material platforms. The final section of the paper presents an overview of current progress and glances at potential directions for future research.
{"title":"Advances in resonator-based Kerr frequency combs with high conversion efficiencies","authors":"Xucheng Zhang, Chunxue Wang, Zhibo Cheng, Congyu Hu, Xingchen Ji, Yikai Su","doi":"10.1038/s44310-024-00030-9","DOIUrl":"10.1038/s44310-024-00030-9","url":null,"abstract":"Recent developments in resonator-based Kerr frequency combs promise excellent applications in a wide range of fields such as biosensing, spectroscopy, optical communications, light detection and ranging (LiDAR), frequency synthesis, astronomical detection, and quantum optics. A key figure of merit (FOM) for Kerr frequency combs is the pump-to-comb conversion efficiency, which is critical for applications requiring sufficient comb power and low power consumption. In this review, we first discuss the limited conversion efficiency of dissipative Kerr soliton in an anomalous dispersion microresonator based on its underlying physical characteristics. And then, we summarize the recent advances in Kerr frequency combs with high conversion efficiencies in both anomalous and normal dispersion regimes. We classify them according to various soliton states, excitation methods as well as novel material platforms. The final section of the paper presents an overview of current progress and glances at potential directions for future research.","PeriodicalId":501711,"journal":{"name":"npj Nanophotonics","volume":" ","pages":"1-21"},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44310-024-00030-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141730379","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-17DOI: 10.1038/s44310-024-00027-4
Ying Kuang, Shuai Wang, Bincheng Mo, Shiyou Sun, Kai Xia, Yuanmu Yang
Metalens is a flat, lightweight optical element that may replace traditional bulky refractive lenses and other components in imaging systems. However, a number of critical challenges still remain for most metalenses demonstrated to date, including limited field-of-view (FOV), depth-of-field (DOF), and working bandwidth, which restrict their use in a real-world application. Here, we propose and experimentally demonstrate a compact imaging system equipped with a metalens that simultaneously features a wide FOV of 140° and an extended DOF ranging from 33 to 150 mm. The metalens further allows polarization selectivity, which can be used to remove unwanted surface reflection of the target scene. Using a narrowband vertical-cavity surface-emitting laser for illumination, we show that the system is well-suited for near-infrared palm vein imaging, an emerging modality for biometric identification. The metalens-integrated imaging system provides uncompromised performance with a greatly simplified form factor compared to a traditional system, which may also be adopted for other applications such as depth sensing and endoscopy.
{"title":"Palm vein imaging using a polarization-selective metalens with wide field-of-view and extended depth-of-field","authors":"Ying Kuang, Shuai Wang, Bincheng Mo, Shiyou Sun, Kai Xia, Yuanmu Yang","doi":"10.1038/s44310-024-00027-4","DOIUrl":"10.1038/s44310-024-00027-4","url":null,"abstract":"Metalens is a flat, lightweight optical element that may replace traditional bulky refractive lenses and other components in imaging systems. However, a number of critical challenges still remain for most metalenses demonstrated to date, including limited field-of-view (FOV), depth-of-field (DOF), and working bandwidth, which restrict their use in a real-world application. Here, we propose and experimentally demonstrate a compact imaging system equipped with a metalens that simultaneously features a wide FOV of 140° and an extended DOF ranging from 33 to 150 mm. The metalens further allows polarization selectivity, which can be used to remove unwanted surface reflection of the target scene. Using a narrowband vertical-cavity surface-emitting laser for illumination, we show that the system is well-suited for near-infrared palm vein imaging, an emerging modality for biometric identification. The metalens-integrated imaging system provides uncompromised performance with a greatly simplified form factor compared to a traditional system, which may also be adopted for other applications such as depth sensing and endoscopy.","PeriodicalId":501711,"journal":{"name":"npj Nanophotonics","volume":" ","pages":"1-7"},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44310-024-00027-4.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141730399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-17DOI: 10.1038/s44310-024-00028-3
Yuning Zhang, Jiayang Wu, Linnan Jia, Di Jin, Baohua Jia, Xiaoyong Hu, David Moss, Qihuang Gong
Optical polarizers are essential components for the selection and manipulation of light polarization states in optical systems. Over the past decade, the rapid advancement of photonic technologies and devices has led to the development of a range of novel optical polarizers, opening avenues for many breakthroughs and expanding applications across diverse fields. Particularly, two-dimensional (2D) materials, known for their atomic thin film structures and unique optical properties, have become attractive for implementing optical polarizers with high performance and new features that were not achievable before. This paper reviews recent progress in 2D-material-based optical polarizers. First, an overview of key properties of various 2D materials for realizing optical polarizers is provided. Next, the state-of-the-art optical polarizers based on 2D materials, which are categorized into spatial-light devices, fiber devices, and integrated waveguide devices, are reviewed and compared. Finally, we discuss the current challenges of this field as well as the exciting opportunities for future technological advances.
{"title":"Advanced optical polarizers based on 2D materials","authors":"Yuning Zhang, Jiayang Wu, Linnan Jia, Di Jin, Baohua Jia, Xiaoyong Hu, David Moss, Qihuang Gong","doi":"10.1038/s44310-024-00028-3","DOIUrl":"10.1038/s44310-024-00028-3","url":null,"abstract":"Optical polarizers are essential components for the selection and manipulation of light polarization states in optical systems. Over the past decade, the rapid advancement of photonic technologies and devices has led to the development of a range of novel optical polarizers, opening avenues for many breakthroughs and expanding applications across diverse fields. Particularly, two-dimensional (2D) materials, known for their atomic thin film structures and unique optical properties, have become attractive for implementing optical polarizers with high performance and new features that were not achievable before. This paper reviews recent progress in 2D-material-based optical polarizers. First, an overview of key properties of various 2D materials for realizing optical polarizers is provided. Next, the state-of-the-art optical polarizers based on 2D materials, which are categorized into spatial-light devices, fiber devices, and integrated waveguide devices, are reviewed and compared. Finally, we discuss the current challenges of this field as well as the exciting opportunities for future technological advances.","PeriodicalId":501711,"journal":{"name":"npj Nanophotonics","volume":" ","pages":"1-17"},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44310-024-00028-3.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141730381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-17DOI: 10.1038/s44310-024-00024-7
Xuetong Zhou, Dan Yi, David W. U Chan, Hon Ki Tsang
Leveraging on the mature processing infrastructure of silicon microelectronics, silicon photonic integrated circuits may be readily scaled to large volume production for low-cost high-volume applications such as optical transceivers for data centers. Driven by the rapid growth of generative artificial intelligence and the resultant rapid increase in data traffic in data centers, new integrated optical transceivers will be needed to support multichannel high-capacity communications beyond 1.6Tb/s. In this paper, we review some of the recent advances in high performance optical waveguide grating couplers (WGC) as a key enabling technology for future high capacity communications. We describe the novel use of shifted-polysilicon overlay gratings on top of the silicon grating that enabled foundry manufactured chips to have fiber-chip coupling losses of under 1 dB. The use of mirror symmetry and resonant cavity enhancement in the design of gratings can increase the 1-dB optical bandwidths of grating couplers to over 100 nm. Multimode waveguide grating couplers (MWGC) may be designed for the selective launch of different modes channels in multimode fibers for mode-division-multiplexing (MDM) communications. The use of different modes or polarizations in optical fibers for high capacity communications requires the unscrambling of data lanes which are mixed together during the optical fiber transmission. We describe how silicon photonic circuits can be used to perform unitary matrix operations and unscramble the different data lanes in multichannel optical communication systems. We also describe recent advances on high-speed silicon modulators for enabling data rates of individual data lanes in an integrated optical transceiver beyond 300 Gb/s.
{"title":"Silicon photonics for high-speed communications and photonic signal processing","authors":"Xuetong Zhou, Dan Yi, David W. U Chan, Hon Ki Tsang","doi":"10.1038/s44310-024-00024-7","DOIUrl":"10.1038/s44310-024-00024-7","url":null,"abstract":"Leveraging on the mature processing infrastructure of silicon microelectronics, silicon photonic integrated circuits may be readily scaled to large volume production for low-cost high-volume applications such as optical transceivers for data centers. Driven by the rapid growth of generative artificial intelligence and the resultant rapid increase in data traffic in data centers, new integrated optical transceivers will be needed to support multichannel high-capacity communications beyond 1.6Tb/s. In this paper, we review some of the recent advances in high performance optical waveguide grating couplers (WGC) as a key enabling technology for future high capacity communications. We describe the novel use of shifted-polysilicon overlay gratings on top of the silicon grating that enabled foundry manufactured chips to have fiber-chip coupling losses of under 1 dB. The use of mirror symmetry and resonant cavity enhancement in the design of gratings can increase the 1-dB optical bandwidths of grating couplers to over 100 nm. Multimode waveguide grating couplers (MWGC) may be designed for the selective launch of different modes channels in multimode fibers for mode-division-multiplexing (MDM) communications. The use of different modes or polarizations in optical fibers for high capacity communications requires the unscrambling of data lanes which are mixed together during the optical fiber transmission. We describe how silicon photonic circuits can be used to perform unitary matrix operations and unscramble the different data lanes in multichannel optical communication systems. We also describe recent advances on high-speed silicon modulators for enabling data rates of individual data lanes in an integrated optical transceiver beyond 300 Gb/s.","PeriodicalId":501711,"journal":{"name":"npj Nanophotonics","volume":" ","pages":"1-14"},"PeriodicalIF":0.0,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44310-024-00024-7.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141730376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-02DOI: 10.1038/s44310-024-00023-8
Yuqi Zhao, Dylan Renaud, Demitry Farfurnik, Yuxi Jiang, Subhojit Dutta, Neil Sinclair, Marko Lončar, Edo Waks
On-chip optical filters are fundamental components in optical signal processing. While rare-earth ion-doped crystals offer ultra-narrow optical filtering via spectral hole burning, their applications have primarily been limited to those using bulk crystals, restricting their utility. In this work, we demonstrate cavity-enhanced spectral filtering based on rare-earth ions in an integrated nonlinear optical platform. We incorporate rare-earth ions into high quality-factor ring resonators patterned in thin-film lithium niobate. By spectral hole burning at 4 K in a critically coupled resonance mode, we achieve bandpass filters ranging from 7 MHz linewidth, with 13.0 dB of extinction, to 24 MHz linewidth, with 20.4 dB of extinction. By reducing the temperature to 100 mK to eliminate phonon broadening, we achieve an even narrower linewidth of 681 kHz, which is comparable to the narrowest filter linewidth demonstrated in an integrated photonic device, while only requiring a small device footprint. Moreover, the cavity enables reconfigurable filtering by varying the cavity coupling rate. For instance, as opposed to the bandpass filter, we demonstrate a bandstop filter utilizing an under-coupled ring resonator. Such versatile integrated spectral filters with high extinction ratio and narrow linewidth could serve as fundamental components for optical signal processing and optical memories on-a-chip.
{"title":"Cavity-enhanced narrowband spectral filters using rare-earth ions doped in thin-film lithium niobate","authors":"Yuqi Zhao, Dylan Renaud, Demitry Farfurnik, Yuxi Jiang, Subhojit Dutta, Neil Sinclair, Marko Lončar, Edo Waks","doi":"10.1038/s44310-024-00023-8","DOIUrl":"10.1038/s44310-024-00023-8","url":null,"abstract":"On-chip optical filters are fundamental components in optical signal processing. While rare-earth ion-doped crystals offer ultra-narrow optical filtering via spectral hole burning, their applications have primarily been limited to those using bulk crystals, restricting their utility. In this work, we demonstrate cavity-enhanced spectral filtering based on rare-earth ions in an integrated nonlinear optical platform. We incorporate rare-earth ions into high quality-factor ring resonators patterned in thin-film lithium niobate. By spectral hole burning at 4 K in a critically coupled resonance mode, we achieve bandpass filters ranging from 7 MHz linewidth, with 13.0 dB of extinction, to 24 MHz linewidth, with 20.4 dB of extinction. By reducing the temperature to 100 mK to eliminate phonon broadening, we achieve an even narrower linewidth of 681 kHz, which is comparable to the narrowest filter linewidth demonstrated in an integrated photonic device, while only requiring a small device footprint. Moreover, the cavity enables reconfigurable filtering by varying the cavity coupling rate. For instance, as opposed to the bandpass filter, we demonstrate a bandstop filter utilizing an under-coupled ring resonator. Such versatile integrated spectral filters with high extinction ratio and narrow linewidth could serve as fundamental components for optical signal processing and optical memories on-a-chip.","PeriodicalId":501711,"journal":{"name":"npj Nanophotonics","volume":" ","pages":"1-11"},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44310-024-00023-8.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141500514","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Gallium (Ga) exhibits remarkable potential in flexible electronics, chemistry, and biomedicine due to its exceptional physical properties. The phase transition and supercooling characteristics of Ga have led to the emergence of numerous valuable applications. In this paper, we capitalize on this foundation by utilizing optofluidic microcavities supporting both high quality factor optical and optomechanical modes to investigate the phase transformation process and supercooling properties of Ga. Our study provides comprehensive insights into the dynamic behavior of Ga during the complete phase transition, such as measuring a hysteresis loop between the solid-to-liquid and liquid-to-solid transitions, revealing nonreciprocal resonance wavelength shift, and identifying a unique metastability state of Ga during melting. The linear thermal expansion coefficients of Ga were precisely measured to be 0.41 × 10−5 K−1 and −0.75 × 10−5 K−1 for solid and liquid Ga, respectively. Our research provides a comprehensive and versatile monitoring platform for newly fabricated liquid metal alloys, offering multidimensional insights into their phase transition behavior.
{"title":"Observation of the liquid metal phase transition in optofluidic microcavities","authors":"Zixiang Fu, Zhenlin Zhao, Ruiji Dong, Junqiang Guo, Yan-Lei Zhang, Shusen Xie, Xianzeng Zhang, Qijing Lu","doi":"10.1038/s44310-024-00022-9","DOIUrl":"10.1038/s44310-024-00022-9","url":null,"abstract":"Gallium (Ga) exhibits remarkable potential in flexible electronics, chemistry, and biomedicine due to its exceptional physical properties. The phase transition and supercooling characteristics of Ga have led to the emergence of numerous valuable applications. In this paper, we capitalize on this foundation by utilizing optofluidic microcavities supporting both high quality factor optical and optomechanical modes to investigate the phase transformation process and supercooling properties of Ga. Our study provides comprehensive insights into the dynamic behavior of Ga during the complete phase transition, such as measuring a hysteresis loop between the solid-to-liquid and liquid-to-solid transitions, revealing nonreciprocal resonance wavelength shift, and identifying a unique metastability state of Ga during melting. The linear thermal expansion coefficients of Ga were precisely measured to be 0.41 × 10−5 K−1 and −0.75 × 10−5 K−1 for solid and liquid Ga, respectively. Our research provides a comprehensive and versatile monitoring platform for newly fabricated liquid metal alloys, offering multidimensional insights into their phase transition behavior.","PeriodicalId":501711,"journal":{"name":"npj Nanophotonics","volume":" ","pages":"1-8"},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44310-024-00022-9.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141500515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-02DOI: 10.1038/s44310-024-00021-w
Stephan Wong, Terry A. Loring, Alexander Cerjan
In the recent years, photonic Chern materials have attracted substantial interest as they feature topological edge states that are robust against disorder, promising to realize defect-agnostic integrated photonic crystal slab devices. However, the out-of-plane radiative losses in those photonic Chern slabs has been previously neglected, yielding limited accuracy for predictions of these systems’ topological protection. Here, we develop a general framework for measuring the topological protection in photonic systems, such as in photonic crystal slabs, while accounting for in-plane and out-of-plane radiative losses. Our approach relies on the spectral localizer that combines the position and Hamiltonian matrices of the system to draw a real-picture of the system’s topology. This operator-based approach to topology allows us to use an effective Hamiltonian directly derived from the full-wave Maxwell equations after discretization via finite-elements method (FEM), resulting in the full account of all the system’s physical processes. As the spectral FEM-localizer is constructed solely from FEM discretization of the system’s master equation, the proposed framework is applicable to any physical system and is compatible with commonly used FEM software. Moving forward, we anticipate the generality of the method to aid in the topological classification of a broad range of complex physical systems.
{"title":"Classifying topology in photonic crystal slabs with radiative environments","authors":"Stephan Wong, Terry A. Loring, Alexander Cerjan","doi":"10.1038/s44310-024-00021-w","DOIUrl":"10.1038/s44310-024-00021-w","url":null,"abstract":"In the recent years, photonic Chern materials have attracted substantial interest as they feature topological edge states that are robust against disorder, promising to realize defect-agnostic integrated photonic crystal slab devices. However, the out-of-plane radiative losses in those photonic Chern slabs has been previously neglected, yielding limited accuracy for predictions of these systems’ topological protection. Here, we develop a general framework for measuring the topological protection in photonic systems, such as in photonic crystal slabs, while accounting for in-plane and out-of-plane radiative losses. Our approach relies on the spectral localizer that combines the position and Hamiltonian matrices of the system to draw a real-picture of the system’s topology. This operator-based approach to topology allows us to use an effective Hamiltonian directly derived from the full-wave Maxwell equations after discretization via finite-elements method (FEM), resulting in the full account of all the system’s physical processes. As the spectral FEM-localizer is constructed solely from FEM discretization of the system’s master equation, the proposed framework is applicable to any physical system and is compatible with commonly used FEM software. Moving forward, we anticipate the generality of the method to aid in the topological classification of a broad range of complex physical systems.","PeriodicalId":501711,"journal":{"name":"npj Nanophotonics","volume":" ","pages":"1-9"},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44310-024-00021-w.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141500526","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-07-02DOI: 10.1038/s44310-024-00026-5
Meng Huang, John Ballato, Anna C. Peacock
Semiconductor core, glass cladding fibres that can be produced with scalable dimensions and unique waveguide designs are offering new opportunities for nonlinear photonics. This paper reviews developments in the fabrication and post-processing of such semiconductor core fibres and their enabling of low loss and high efficiency nonlinear components across wavelengths spanning the near- to mid-infrared. Through adaption and expansion of the production processes, routes to new core materials are being opened that could extend the application space, whilst all-fibre integration methods will result in more robust and practical semiconductor systems. Through continued improvement in the core materials, fibre designs and transmission losses, semiconductor fibres are poised to bring unique functionality to both the fibre and semiconductor research fields and their practical application into a myriad of optoelectronic devices.
{"title":"Semiconductor core fibres: a scalable platform for nonlinear photonics","authors":"Meng Huang, John Ballato, Anna C. Peacock","doi":"10.1038/s44310-024-00026-5","DOIUrl":"10.1038/s44310-024-00026-5","url":null,"abstract":"Semiconductor core, glass cladding fibres that can be produced with scalable dimensions and unique waveguide designs are offering new opportunities for nonlinear photonics. This paper reviews developments in the fabrication and post-processing of such semiconductor core fibres and their enabling of low loss and high efficiency nonlinear components across wavelengths spanning the near- to mid-infrared. Through adaption and expansion of the production processes, routes to new core materials are being opened that could extend the application space, whilst all-fibre integration methods will result in more robust and practical semiconductor systems. Through continued improvement in the core materials, fibre designs and transmission losses, semiconductor fibres are poised to bring unique functionality to both the fibre and semiconductor research fields and their practical application into a myriad of optoelectronic devices.","PeriodicalId":501711,"journal":{"name":"npj Nanophotonics","volume":" ","pages":"1-12"},"PeriodicalIF":0.0,"publicationDate":"2024-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.nature.com/articles/s44310-024-00026-5.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141500487","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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