Universidad Complutense de Madrid, Facultad de Ciencias Físicas, Ciudad Universitaria s/n, Madrid 28040, Spain
Increasing interest has been drawn to optical manipulation of metal (plasmonic) nanoparticles due to their unique response on electromagnetic radiation, prompting numerous applications in nanofabrication, photonics, sensing, etc. The familiar point-like laser tweezers rely on the exclusive use of optical confinement forces that allow stable trapping of a single metal nanoparticle in 3D. Simultaneous all-optical (contactless) confinement and motion control of single and multiple metal nanoparticles is one of the major challenges to be overcome. This article reports and provides guidance on mastering a sophisticated manipulation technique harnessing confinement and propulsion forces, enabling simultaneous all-optical confinement and motion control of nanoparticles along 3D trajectories. As an example, for the first time to our knowledge, programmable transport of gold and silver nanospheres with a radius of 50 and 30 nm, respectively, along 3D trajectories tailored on demand, is experimentally demonstrated. It has been achieved by an independent design of both types of optical forces in a single-beam laser trap in the form of a reconfigurable 3D curve. The controlled motion of multiple nanoparticles, far away from chamber walls, allows studying induced electrodynamic interactions between them, such as plasmonic coupling, observed in the presented experiments. The independent control of optical confinement and propulsion forces provides enhanced flexibility to manipulate matter with light, paving the way to new applications involving the formation, sorting, delivery, and assembling of nanostructures.
1 Institute of Microelectronics, A*STAR (Agency for Science, Technology and Research), Singapore 138634, Singapore
2 Current Address: School of Microelectronics Science and Technology, Sun Yat-sen University, Zhuhai 519082, China
Optical color filters are widely applied in many areas including display, imaging, sensing, holography, energy harvest, and measurement. Traditional dye-based color filters have drawbacks such as environmental hazards and instability under high temperature and ultraviolet radiation. With advances in nanotechnology, structural color filters, which are based on the interaction of light with designed nanostructures, are able to overcome the drawbacks. Also, it is possible to fabricate structural color filters using standard complementary metal-oxide-semiconductor (CMOS) fabrication facilities with low cost and high volume. In this work, metasurface-based subtractive color filters (SCFs) are demonstrated on 12-inch (300-mm) glass wafers using a CMOS-compatible fabrication process. In order to make the transmissive-type SCF on a transparent glass wafer, an in-house developed layer transfer process is used to solve the glass wafer handling issue in fabrication tools. Three different heights of embedded silicon nanopillars (110, 170, and 230 nm) are found to support magnetic dipole resonances. With pillar height and pitch variation, SCFs with different displayed colors are achieved. Based on the resonance wavelength, the displayed color of the metasurface is verified within the red-yellow-blue color wheel. The simulation and measurement results are compared and discussed. The work provides an alternative design for high efficiency color filters on a CMOS-compatible platform, and paves the way towards mass-producible large-area metasurfaces.
1 CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026, China
2 CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei 230026, China
The nonlinear fluorescence emission has been widely applied for high spatial resolution optical imaging. Here, we studied the fluorescence anomalous saturating effect of the nitrogen vacancy defect in diamond. The fluorescence reduction was observed with high power laser excitation. It increased the nonlinearity of the fluorescence emission, and changed the spatial frequency distribution of the fluorescence image. We used a differential excitation protocol to extract the high spatial frequency information. By modulating the excitation laser’s power, the spatial resolution of imaging was improved approximately 1.6 times in comparison with the confocal microscopy. Due to the simplicity of the experimental setup and data processing, we expect this method can be used for improving the spatial resolution of sensing and biological labeling with the defects in solids.
1 Nanophotonics and Optoelectronics Research Center, Qian Xuesen Laboratory of Space Technology, China Academy of Space Technology, Beijing 100094, China
2 e-mail: xiaolin@qxslab.cn
Mid-infrared thermal detectors have very important applications in the aerospace and military fields. However, due to the low heat transfer efficiency and slow response time, their application has been greatly restricted. Here, we theoretically demonstrate a dual-band perfect absorber for a mid-infrared detector based on a dielectric metal metasurface, and the optical and thermal properties are analyzed in detail. Simulation results show that the two narrow absorption peaks, corresponding to the absorption value of 97.5% at with and 99.7% at with , respectively, are achieved, and their different dependences on the structural parameters have been studied. A thermal detector at room temperature with total response time within 1.3 ms for dual-band and 0.4 ms for single-band is realized when the incident light flux is for an average temperature increase of . Our study offers a promising approach for designing a narrowband mid-infrared perfect absorber and a high-performance photodetector in nano-integrated photonics.
1 Key Laboratory of Optoelectronic Materials and Technologies, School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
2 Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Opto-Electronic Information Acquisition and Manipulation of Ministry of Education, Anhui University, Hefei 230601, China
3 Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), Zhuhai 519000, China
4 e-mail: shenyuecheng@mail.sysu.edu.cn
5 e-mail: lzhh88@mail.sysu.edu.cn
The Gerchberg–Saxton (GS) algorithm, which retrieves phase information from the measured intensities on two related planes (the source plane and the target plane), has been widely adopted in a variety of applications when holographic methods are challenging to be implemented. In this work, we showed that the GS algorithm can be generalized to retrieve the unknown propagating function that connects these two planes. As a proof-of-concept, we employed the generalized GS (GGS) algorithm to retrieve the optical transmission matrix (TM) of a complex medium through the measured intensity distributions on the target plane. Numerical studies indicate that the GGS algorithm can efficiently retrieve the optical TM while maintaining accuracy. With the same training data set, the computational time cost by the GGS algorithm is orders of magnitude less than that consumed by other non-holographic methods reported in the literature. Besides numerical investigations, we also experimentally demonstrated retrieving the optical TMs of a stack of ground glasses and a 1-m-long multimode fiber using the GGS algorithm. The accuracy of the retrieved TM was evaluated by synthesizing high-quality single foci and multiple foci on the target plane through these complex media. These results indicate that the GGS algorithm can handle a large TM with high efficiency, showing great promise in a variety of applications in optics.
1 School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, China
2 Department of Applied Physics, KTH Royal Institute of Technology, Stockholm 11419, Sweden
3 Wuhan National Laboratory for Optoelectronics, Wuhan 430074, China
A novel power-efficient reconfigurable mode converter is proposed and experimentally demonstrated based on cross-connected symmetric Y-junctions assisted by thermo-optic phase shifters on a silicon-on-insulator platform. Instead of using conventional Y-junctions, subwavelength symmetric Y-junctions are utilized to enhance the mode splitting ability. The reconfigurable functionality can be realized by controlling the induced phase differences. Benefited from the cross-connected scheme, the number of heating electrodes can be effectively reduced, while the performance of the device is maintained. With only one-step etching, our fabricated device shows the average insertion losses and cross talks are less than 2.45 and , respectively, measured with conversions between two arbitrary compositions of the first four TE modes over an observable 60 nm bandwidth. The converter is switchable and CMOS-compatible, and could be extended for more modes; hence, it can be potentially deployed for advanced and flexible mode multiplexing optical networks-on-chip.
Department of Physics, Pusan National University, Geumjeong-Gu, Busan 46241, Republic of Korea
We report the demonstration of a second-order interference experiment by use of thermal light emitted from a warm atomic ensemble in two spatially separated unbalanced Michelson interferometers (UMIs). This novel multipath correlation interference with thermal light has been theoretically proposed by Tamma [New J. Phys.18, 032002 (2016)NJOPFM1367-263010.1088/1367-2630/18/3/032002]. In our experiment, the bright thermal light used for second-order interference is superradiantly emitted via collective two-photon coherence in Doppler-broadened cascade-type atoms. Owing to the long coherence time of the thermal light from the atomic ensemble, we observe its second-order interference in the two independent UMIs by means of time-resolved coincidence detection. The temporal waveforms of the interfering thermal light in the two spatially separated UMIs exhibit similarities with the temporal two-photon waveform of time–energy entangled photon pairs in Franson interferometry. Our results can contribute toward a better understanding of the relation between first- and second-order interferences that are at the heart of photonics-based quantum information science.
1 Department of Electronic Engineering, East China Normal University, Shanghai 200241, China
2 Ministry of Education Nanophotonics & Advanced Instrument Engineering Research Center, East China Normal University, Shanghai 200241, China
3 Shanghai Institute of Intelligent Electronics & Systems, Fudan University, Shanghai 200433, China
4 Institute for Solid State Physics, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581, Japan
5 e-mail: egweng@ee.ecnu.edu.cn
6 e-mail: sqchen@ee.ecnu.edu.cn
All-inorganic perovskite micro/nanolasers are emerging as a class of miniaturized coherent photonic sources for many potential applications, such as optical communication, computing, and imaging, owing to their ultracompact sizes, highly localized coherent output, and broadband wavelength tunability. However, to achieve single-mode laser emission in the microscale perovskite cavity is still challenging. Herein, we report unprecedented single-mode laser operations at room temperature in self-assembly microcavities over an ultrawide pumping wavelength range of 400–2300 nm, covering one- to five-photon absorption processes. The superior frequency down- and upconversion single-mode lasing manifests high multiphoton absorption efficiency and excellent optical gain from the electron–hole plasma state in the perovskite microcavities. Through direct compositional modulation, the wavelength of a single-mode microlaser can be continuously tuned from blue-violet to green (427–543 nm). The laser emission remains stable and robust after long-term high-intensity excitation for over 12 h (up to excitation cycles) in the ambient atmosphere. Moreover, the pump-wavelength dependence of the threshold, as well as the detailed lasing dynamics such as the gain-switching and electron–hole plasma mechanisms, are systematically investigated to shed insight into the more fundamental issues of the lasing processes in perovskite microcavities.
1 State Key Laboratory of Transient Optics and Photonics, Xi’an Institute of Optics and Precision Mechanics (XIOPM), Chinese Academy of Sciences (CAS), Xi’an 710119, China
2 University of Chinese Academy of Sciences, Beijing 100049, China
3 Department of Physics and Materials Science, City University of Hong Kong, Hong Kong, China
4 e-mail: wwq@opt.ac.cn
5 e-mail: wfuzhang@opt.ac.cn
Soliton microcombs (SMCs) are spontaneously formed in a coherently pumped high-quality microresonator, which provides a new tool for use as an on-chip frequency comb for applications of high-precision metrology and spectroscopy. However, generation of SMCs seriously relies on advanced experimental techniques from professional scientists. Here, we experimentally demonstrate a program-controlled single SMC source where the intracavity thermal effect is timely balanced using an auxiliary laser during single SMC generation. The microcomb power is adopted as the criteria for microcomb states discrimination and a forward and backward thermal tuning technique is employed for the deterministic single SMC generation. Further, based on a closed-loop control system, the repetition rate stability of the SMC source improved more than 20 times and the pump frequency can be continuously tuned by simply changing the operation temperature. The reliability of the SMC source is verified by consecutive 200 generation trials and maintaining over 10 h. We believe the proposed SMC source will have significant promising influences in future SMC-based application development.
1 Institute of Micro-nano Photonics & Beam Steering, School of Science, Nanjing University of Science and Technology, Nanjing 210094, China
2 Centre for Disruptive Photonic Technologies, The Photonics Institute, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371, Singapore
3 College of Physics and Electronic Information Science, Tianjin Normal University, Tianjin 300387, China
4 e-mail: jly@njust.edu.cn
5 e-mail: zexiang@ntu.edu.sg
Understanding the mode’s origin in planar metamaterials is fundamental for related applications in nanophotonics and plasmonics. For complex planar metamaterials, conventional analysis that directly obtains the final charge/current distribution of a mode is usually difficult in helping to understand the mode’s origin. In this paper, we propose a mode evolution method (MEM) with a core analysis tool, i.e., plasmonic evolution maps (PEMs), to describe the mode evolution in several complementary planar metamaterials with designed plasmonic atoms/molecules. The PEMs could not only clearly explain a mode’s origin, but also reveal the role of a structure’s symmetry in the mode formation process. The MEM with PEMs can work as a simple, efficient, and universal approach for the mode analysis in different kinds of planar metamaterials.
1 School of Electronic Science and Applied Physics, Hefei University of Technology, Hefei 230009, China
2 State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006, China
3 Stanford Institute for Materials and Energy Sciences, Menlo Park, California 94025, USA
4 State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China
5 Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
6 Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, UK
7 e-mail: meifeng@sxu.edu.cn
8 e-mail: nyxu@hfut.edu.cn
9 e-mail: hengshen@nbi.dk
Harnessing the dynamics of complex quantum systems is an area of much interest and a quantum simulator has emerged as a promising platform to probe exotic topological phases. Since the flexibility offered by various controllable quantum systems has helped gain insight into the quantum simulation of such complicated problems, an analog quantum simulator has recently shown its feasibility to tackle the problems of exploring topological phases. However, digital quantum simulation and the detection of topological phases still remain elusive. Here, we develop and experimentally realize the digital quantum simulation of topological phases with a solid-state quantum simulator at room temperature. Distinct from previous works dealing with static topological phases, the topological phases emulated here are Floquet topological phases. Furthermore, we also illustrate the procedure of digitally simulating a quantum quench and observing the nonequilibrium dynamics of Floquet topological phases. Using a quantum quench, the 0- and -energy topological invariants are unambiguously detected through measuring time-averaged spin polarizations. We believe our experiment opens up a new avenue to digitally simulate and detect Floquet topological phases with fast-developed programmable quantum simulators.
Institute for Physics, University of Rostock, 18059 Rostock, Germany
We report on the experimental demonstration of two-photon quantum walks at the edge of a photonic Su–Schrieffer–Heeger lattice and compare them to those observed when launching photons at the edge of a homogeneous lattice. Whereas at the topological edge, one of the photons primarily remains close to the edge, both photons penetrate freely from the trivial edge into the bulk. This behavior manifests also in the average inter-particle distance, which is significantly larger at the topological edge. Hence, for a given propagation length, the entangled two-photon state launched at the topological edge extends over a wider domain of the lattice.
1 Key Laboratory of Advanced Transducers and Intelligent Control System, Ministry of Education, Taiyuan University of Technology, Taiyuan 030024, China
2 School of Electronics and Information, Northwestern Polytechnical University, Xi'an 710072, China
3 School of Information Engineering, Guangdong University of Technology, Guangzhou 510006, China
4 Key Laboratory of Specialty Fiber Optics and Optical Access Networks, Shanghai University, Shanghai 200444, China
5 Department of Informatics and Computer Engineering, University of West Attica, Athens 12243, Greece
6 School of Electronic Engineering, Bangor University, Wales LL57 1UT, UK
7 Key Laboratory of Radar Imaging and Microwave Photonics, Ministry of Education, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
We present a simple approach based on photonic reservoir computing (P-RC) for modulation format identification (MFI) in optical fiber communications. Here an optically injected semiconductor laser with self-delay feedback is trained with the representative features from the asynchronous amplitude histograms of modulation signals. Numerical simulations are conducted for three widely used modulation formats (on–off keying, differential phase-shift keying, and quadrature amplitude modulation) for various transmission situations where the optical signal-to-noise ratio varies from 12 to 26 dB, the chromatic dispersion varies from to 500 ps/nm, and the differential group delay varies from 0 to 20 ps. Under these situations, final simulation results demonstrate that this technique can efficiently identify all those modulation formats with an accuracy of after optimizing the control parameters of the P-RC layer such as the injection strength, feedback strength, bias current, and frequency detuning. The proposed technique utilizes very simple devices and thus offers a resource-efficient alternative approach to MFI.
1 Photonics Initiative, Advanced Science Research Center, City University of New York, New York, New York 10031, USA
2 Physics Program, Graduate Center, City University of New York, New York, New York 10016, USA
3 Institute for Complex Systems, National Research Council (ISC-CNR), Via dei Taurini 19, 00185 Rome, Italy
4 Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
5 State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics, School of Physics, Peking University, Beijing 100871, China
6 e-mail: aalu@gc.cuny.edu
7 e-mail: laura.pilozzi@isc.cnr.it
8 e-mail: haitanxu@pku.edu.cn
9 e-mail: fanjy@sustech.edu.cn
Topological photonics has been opening exciting opportunities in recent optics research. In this feature issue, we present a collection of papers outlining state-of-the-art and application perspectives for this thriving field of research.
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