- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Ultrawide tunability
摘要： Using light to manipulate small particles has proven an indispensable tool for ‘tweezing’, sorting and force measurements. To achieve effective optical traps with high ‘stiffness’, researchers often go to great lengths to tailor light fields, for example by using holographic elements. Now, Aliaksandra Ivinskaya and colleagues from Russia, the USA, the UK and Israel predict that small particles can be manipulated using a plane wave of light and a simple flat surface of an anisotropic media supporting hyperbolic modes. Their hyperbolic metamaterial is composed of metal and dielectric layers and is potentially less affected by losses and offers more broadband capability than purely plasmonic approaches. In their theoretical study a small dielectric sphere near a hyperbolic metamaterial is considered. The particle is sufficiently small to provide the required momentum to excite both surface plasmon and bulk hyperbolic waves from incident plane waves. Strong optical pulling forces were predicted over the 400–800 nm wavelength range thanks to the broadband high density of states of hyperbolic modes.
关键词： hyperbolic modes,nano-optics,optical manipulation,metasurface,plasmon
更新于2025-09-09 09:28:46
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Compact and efficient
摘要： Using light to manipulate small particles has proven an indispensable tool for ‘tweezing’, sorting and force measurements. To achieve effective optical traps with high ‘stiffness’, researchers often go to great lengths to tailor light fields, for example by using holographic elements. Now, Aliaksandra Ivinskaya and colleagues from Russia, the USA, the UK and Israel predict that small particles can be manipulated using a plane wave of light and a simple flat surface of an anisotropic media supporting hyperbolic modes. Their hyperbolic metamaterial is composed of metal and dielectric layers and is potentially less affected by losses and offers more broadband capability than purely plasmonic approaches. In their theoretical study a small dielectric sphere near a hyperbolic metamaterial is considered. The particle is sufficiently small to provide the required momentum to excite both surface plasmon and bulk hyperbolic waves from incident plane waves. Strong optical pulling forces were predicted over the 400–800 nm wavelength range thanks to the broadband high density of states of hyperbolic modes.
关键词： hyperbolic modes,nano-optics,optical manipulation,metasurface,plasmon
更新于2025-09-09 09:28:46
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Optical signatures of Dirac nodal lines in NbAs <sub/>2</sub>
摘要： Using polarized optical and magneto-optical spectroscopy, we have demonstrated universal aspects of electrodynamics associated with Dirac nodal lines that are found in several classes of unconventional intermetallic compounds. We investigated anisotropic electrodynamics of NbAs2 where the spin-orbit coupling (SOC) triggers energy gaps along the nodal lines. These gaps manifest as sharp steps in the optical conductivity spectra σ1(ω). This behavior is followed by the linear power-law scaling of σ1(ω) at higher frequencies, consistent with our theoretical analysis for dispersive Dirac nodal lines. Magneto-optics data affirm the dominant role of nodal lines in the electrodynamics of NbAs2.
关键词： Dirac fermions,nodal-line semimetal,optical conductivity,magneto-optics
更新于2025-09-09 09:28:46
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Radiation damage free ghost diffraction with atomic resolution
摘要： The x-ray free electron lasers can enable diffractive structural determination of protein nanocrystals and single molecules that are too small and radiation-sensitive for conventional x-ray diffraction. However the electronic form factor may be modified during the ultrashort x-ray pulse due to photoionization and electron cascade caused by the intense x-ray pulse. For general x-ray imaging techniques, the minimization of the effects of radiation damage is of major concern to ensure reliable reconstruction of molecular structure. Here we show that radiation damage free diffraction can be achieved with atomic spatial resolution by using x-ray parametric down-conversion and ghost diffraction with entangled photons of x-ray and optical frequencies. We show that the formation of the diffraction patterns satisfies a condition analogous to the Bragg equation, with a resolution that can be as fine as the crystal lattice length scale of several ?ngstrom. Since the samples are illuminated by low energy optical photons, they can be free of radiation damage.
关键词： atomic resolution,x-ray quantum optics,diffraction imaging
更新于2025-09-09 09:28:46
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Optimal quantum-programmable projective measurement with linear optics
摘要： We present a scheme for a universal device which can be programed by quantum states to approximate a chosen projective measurement to a given precision. Our scheme can be viewed as an extension of the swap test to the instance where one state is supplied many times. As such, it has many potential applications given the variety of quantum information tasks which make use of the swap test. In particular, we show that our scheme is optimal for state discrimination under the one-sided error requirement, and optimally approximates any projective measurement. Furthermore, we propose a practical implementation of our scheme with passive linear optics, which involves a simple interferometer composed only of balanced beam splitters.
关键词： Hadamard interferometer,swap test,linear optics,state discrimination,quantum-programmable projective measurement
更新于2025-09-09 09:28:46
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New Insight into Complex Mode Matching Method for Modeling and Simulation of Surface-Emitting Grating Couplers
摘要： A complex mode matching method is investigated for modeling and simulation of surface-emitting grating couplers. It is noted that the degree of accuracy for the complex modes obtained numerically plays significant role in determining the overall accuracy of the mode matching method, regardless of the number of modes used in the mode expansion. Furthermore, a reduced two-dimensional (2D) model by using the effective index method is shown to yield highly accurate results in comparison with the full three-dimensional (3D) model for practical grating couplers, which allows huge saving in computational resources for performance simulation and design optimization. Lastly, we employ a robust genetic algorithm (i.e., the particle swarm method) for optimization against grating period for maximum coupling efficiency to a single mode optical fiber and produces results consistent with those reported in literature.
关键词： radiation coupling,Integrated optics devices,mode-matching method
更新于2025-09-09 09:28:46
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Reconfigurable On-Chip Mode Exchange for Mode-Division Multiplexing Optical Networks
摘要： Data exchange plays a key role in enhancing network resources utilization and optimizing network performance. In this paper, a data exchange device based on mode-division multiplexing (MDM) technology is proposed and demonstrated, which is capable of exchanging data information between a fundamental mode (TE0) signal and an arbitrary high-order mode (TEx) signal. We experimentally demonstrate the exchange between a TE0 mode signal and a TE1 mode signal using single microring resonator. The insertion loss is about 7.5 dB including terminal coupling loss, the extinction ratio is more than 20 dB within the C band. The crosstalk for the TE1-to-TE0 and TE0-to-TE1 mode conversions is measured to be less than -22 dB and -16 dB, respectively. Clear and open eye diagrams of two different wavelength signals at 10 Gb/s are obtained. The proposed scheme is expected to be used for on-chip MDM networks in future due to its scalability, compact size and low power consumption.
关键词： photonic integrated circuits,microring resonator (MRR),Silicon photonics,mode-division multiplexing,integrated optics
更新于2025-09-09 09:28:46
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Interleaved Silicon Nitride AWG Spectrometers
摘要： Interleaved arrayed waveguide gratings (AWGs) have a great potential in providing large channel counts and narrower channel spacings for many applications, including optical communication, spectroscopy, and imaging. Here, a 75-channel silicon nitride based interleaved AWG was experimentally demonstrated. The design is comprised of a 3-channel primary AWG with 1 nm of resolution and three 25-channel secondary AWGs each with 3 nm of resolution. The final device has a spectral resolution of 1 nm over 75 nm bandwidth centered at 1550 nm. Its performance is compared with a conventional AWG spectrometer with 75 nm of bandwidth and 1 nm of resolution. The interleaved AWG demultiplexer showed lower crosstalk and better uniformity in addition to being two times smaller than the conventional design.
关键词： interleaver,C-band,arrayed waveguide grating,silicon nitride,demultiplexer,Integrated optics
更新于2025-09-09 09:28:46
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[IEEE ICASSP 2018 - 2018 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) - Calgary, AB (2018.4.15-2018.4.20)] 2018 IEEE International Conference on Acoustics, Speech and Signal Processing (ICASSP) - High-Speed Light Field Image Formation Analysis Using Wavefield Modeling with Flexible Sampling
摘要： Understanding the image formation inside plenoptic cameras is significant for the investigations of improving the low spatial resolution. Most researches explore the image formation from the perspective of geometric optics. However, as the hardware components in combination with low-aperture optical systems become smaller and smaller, geometric analysis will no longer be valid due to diffraction effects. In this paper, a wave-optic-based model is proposed that uses the Fresnel diffraction equation to propagate the whole object field into the plenoptic systems. The proposed model employs averaging of intensities on the sensor from uncorrelated coherent wave to avoid interference during propagations among the optical component planes. Besides, by utilizing the method of multiple partial propagations, the proposed model is much flexible at sampling on propagation planes. In order to verify the effectiveness of the proposed model, numerical simulations are conducted by comparing with existing wave optic model under different optical configurations of plenoptic cameras. Results demonstrate that the proposed model can describe the light field image formation properly. In addition, the time for image formation has been reduced by a factor of 19.22 using the proposed model.
关键词： Plenoptic cameras,multiple partial propagations,image formation,Fresnel diffraction equation,wave optics
更新于2025-09-09 09:28:46
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[IEEE 2018 IEEE Research and Applications of Photonics In Defense Conference (RAPID) - Miramar Beach, FL (2018.8.22-2018.8.24)] 2018 IEEE Research and Applications of Photonics In Defense Conference (RAPID) - Applications of Microwave Photonic Processing
摘要： We review recent advances in microwave photonic processors for full spectrum awareness and frequency translation. Hybrid integration progress for these systems is shown along with the latest waveguide and chip-scale technologies to reduce SWaP and improve performance.
关键词： Nonlinear optics,Subsystem integration and techniques,Radio frequency photonics,integrated optics,Integrated optics devices
更新于2025-09-04 15:30:14