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Optical Sensing of Broadband RF Magnetic Field Using a Micrometer-Sized Diamond
摘要： High-resolution ?eld imaging with minimized invasiveness is of growing interest with the development of radio frequency (RF) integrated circuits and planar antenna characterization. In this paper, we propose an optical broadband sensor with static offset magnetic ?eld using a diamond crystal that contains an ensemble of nitrogen-vacancy (NV) centers. The spatial resolution of micrometer scale is demonstrated by using a diamond crystal of this size. This technique is based on the modulation of ?uorescence emitting by NV center under green laser excitation, by an off-axis magnetic ?eld at radio frequencies. We demonstrate experimentally the detection of an RF magnetic ?eld, with minimum measurable amplitude on the order of 0.1 Gauss, which is limited by the noise ?oor of the avalanche photodetector. The sensitivity can be further improved by noise suppression in optics. The bandwidth of the sensor is measured to be 15 MHz.
关键词： near-?eld imaging,magnetic ?eld,magnetic resonance,Instrumentation and measurement,real time,laser
更新于2025-09-23 15:23:52
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Quantum dot based mid-infrared photodetector enhanced by a hybrid metal-dielectric optical antenna
摘要： Surface plasmon waves and Rayleigh anomaly are characteristic optical phenomena exhibited by periodic subwavelength grating structures. In this paper, a hybrid metal-dielectric metasurface is proposed to improve the photoresponse of Ge/Si quantum dot infrared photodetectors (QDIPs) with the limited absorption layer thickness. The composite metasurface consists of a regular array of silicon pillars. The pillars protrude through subwavelength holes in a perforated gold ?lm on detector top. We demonstrate that by combining e?ects of dielectric and plasmonic metal components, the QDIP photoresponse can be signi?cantly improved compared to case when all-dielectric and metal gratings work alone. We observe about 4 times photoresponse enhancement with the hybrid metasurface device relative to a common plasmonic design with the two-dimensional metal hole array. Compared with a bare QDIP, the peak responsivity of the hybrid detector at a wavelength of 4.4 μm is increased by a factor of 15. The enhanced sensitivity is supposed to arise from coupling of the surface plasmon resonance and di?ractive e?ect related to the Rayleigh anomaly.
关键词： infrared photodetection,quantum dots,surface plasmons,enhancement,near-?eld
更新于2025-09-23 15:21:01
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Metamaterials, Anapoles and Flying Donuts
摘要： Heat-assisted magnetic recording (HAMR) allows for data writing in hard disks beyond 1 Tb/in2 areal density, by temporarily heating the area of a single bit to its Curie temperature. The metallic optical antenna or near-?eld transducer (NFT), used to apply the nanoscale heating to the media, may self-heat by several hundreds of degrees. With the NFT reaching such extreme temperatures, demonstrations of HAMR technology experience write-head lifetimes that are orders of magnitude less than that required for a commercial product. Hence, heating of the NFT is of upmost importance. In this paper, we ?rst derive fundamental limits on the temperature ratio NFT/Media to drive NFT design choices for low-temperature operation. Next, we employ inverse electromagnetic design software, which solves for unexpected geometries of the NFT and waveguide. We present computationally generated designs for the waveguide feeding the NFT that offer a 50% reduction in NFT self-heating (～220 °C) compared with typical industry designs.
关键词： HAMR,optimization,plasmonics,nanophotonics,near-?eld transducer (NFT),inverse problem,heat-assisted magnetic recording thermal,computational electromagnetics,hard disks,gradient methods,management,Adjoint method,optical antenna
更新于2025-09-19 17:13:59
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Generation of Flat Top Surface Plasmon Polariton Beams by Near Field Holography
摘要： Controlling the shape and trajectory of the surface plasmon polariton (SPP) beams is the key to all SPP-based applications. In this paper, a novel plasmonic device that can generate in-plane ?at top SPP beams is designed by near ?eld holography. The relationship between the transverse pro?le intensity of the generated ?at top SPP beams and the structural parameters of the designed device is analyzed. The results of this paper can provide the possibility for further practical application utilizing ?at top SPP beams.
关键词： surface plasmonic polariton,near ?eld holography,?at top SPP beams
更新于2025-09-16 10:30:52
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Near-field resonances in photon emission via interaction of electrons with coupled nanoparticles
摘要： In this work we construct the ?rst-principles theory for the near-?eld resonances arising in the system of two different coupled nanoparticles excited by the external ?eld. The obtained expressions are valid for an arbitrary external ?eld; the detailed analysis is performed for the case of a fast electron passing by. The energy of electron is arbitrary, so the results are valid both for relativistic and nonrelativistic electrons. We have obtained rigorous analytical solution for the radiation ?eld and for distribution of radiation over angles and frequencies. The effect of interaction between the single particles manifests itself very distinctly in conditions of resonance, resulting in a spectral shift of the radiation maximum, signi?cant increase of its altitude, and, interestingly, in clear oscillations in radiation intensity not only when the particles are very close to each other, but even when the distance between the particles exceeds considerably their sizes. It attests to the strong in?uence of interaction on the radiation processes in a system of coupling particles.
关键词： coupled nanoparticles,photon emission,near-?eld resonances,radiation processes,electron interaction
更新于2025-09-12 10:27:22
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[IEEE 2018 IEEE Indian Conference on Antennas and Propogation (InCAP) - Hyderabad, India (2018.12.16-2018.12.19)] 2018 IEEE Indian Conference on Antennas and Propogation (InCAP) - UHF Wideband Near-Field Coupled Antenna
摘要： In this work we present a near-?eld coupled antenna pair for UHF-RFID operation. The antenna pair is a suitable choice for applications involving detection of RFID tags inside an enclosure, where the power is coupled into the enclosure using the near-?eld coupling of the proposed antenna pair. The important design parameters of the antenna for the optimum performance in the coupled mode are presented and discussed. The proposed antenna pair presents a coupling better than 2 dB from 850 MHz to 950 MHz thus operable in the entire RFID frequency range.
关键词： high impedance surface,loop antennas,near-?eld coupling,UHF,RFID
更新于2025-09-11 14:15:04
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Magnetic Field Effect of Near-Field Radiative Heat Transfer for SiC Nanowires/Plates
摘要： The SiC micro/nano-scale structure has advantages for enhancing nonreciprocal absorptance for photovoltaic use due to the magneto optical effect. In this work, we demonstrate the near-?eld radiative transfer between two aligned SiC nanowires/plates under different magnetic ?eld intensities, in which Lorentz-Drude equations of the dielectric constant tensor are proposed to describe the dielectric constant as a magnetic ?eld applied on the SiC structure. The magnetic ?eld strength is quali?ed in this study. Using local effective medium theory and the ?uctuation-dissipation theorem, we evaluate the near-?eld radiation between SiC nanowires with different ?lling ratios and gap distances under an external magnetic ?eld. Compared to the near-?eld heat ?ux between two SiC plates, the one between SiC nanowires can be enhanced with magnetic ?eld intensity, a high ?lling ratio, and a small gap distance. The electric ?eld intensity is also presented for understanding light coupling, propagation, and absorption nature of SiC grating under variable incidence angles and magnetic ?eld strengths. This relative study is useful for thermal radiative design in optical instruments.
关键词： near-?eld radiation,SiC nanowires,magnetic ?eld effect
更新于2025-09-11 14:12:44
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Modified physical optics algorithm for near field scattering
摘要： A novel modi?ed physical optics algorithm is proposed to overcome the dif?culties of near ?eld scattering prediction for classical physical optics. The method is applied to calculating the near ?eld radar cross section of electrically large objects by taking into account the in?uence of the distinct wave propagation vector, the near ?eld Green function, and the antenna radiation pattern. By setting up local reference coordinates, each partitioned facet has its own distinct wave front curvature. The radiation gain for every surface element is taken into consideration based on the modulation of the antenna radiation pattern. The Green function is re?ned both in amplitude and phase terms and allows for near ?eld calculation. The scattered characteristics of the near ?eld targets are studied by numerical simulations. The results show that the approach can achieve a satisfactory accuracy.
关键词： physical optics,scattering,near ?eld
更新于2025-09-09 09:28:46
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Accuracy Test of Iterative Physical Optics for Analyzing Scattering by Nonperfectly Conducting Bodies Using Impedance Boundary Conditions
摘要： An iterative physical optics has been used to analyze the electromagnetic scattering by electrically large and complex objects with nonperfectly conducting surfaces. The iterative physical optics is near-?eld corrected based on the magnetic ?eld integral equation. By comparing the scatterings computed by the iterative physical optics and multilevel fast mutipole method, the accuracy of the iterative physical optics is investigated.
关键词： magnetic ?eld integral equation (MFIE),near-?eld correction,iterative physical optics (IPO)
更新于2025-09-04 15:30:14
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[Institution of Engineering and Technology 12th European Conference on Antennas and Propagation (EuCAP 2018) - London, UK (9-13 April 2018)] 12th European Conference on Antennas and Propagation (EuCAP 2018) - Nonconvex Phaseless Near-Field Far-Field Transformation for Electrically Large Problems
摘要： A phaseless near-?eld far-?eld transformation (NFFFT) based on nonconvex optimization and suitable for electrically large problems is presented. Features include ef?cient forward and adjoint operators taken from the fast irregular antenna ?eld transformation algorithm (FIAFTA) and the memory limited L-Broyden, Fletcher, Goldfarb and Shannon (L-BFGS) method for the solution of the nonconvex optimization. Measurement results show the bene?t of specialized probes, which effectively incorporate the knowledge of partial phase differences, for phaseless near-?eld measurements. The applicability of those probes and of the proposed nonconvex transformation algorithm to electrically large problems is veri?ed by measured and simulated results.
关键词： electrically large,inverse problem,phaseless,near-?eld far-?eld transformation
更新于2025-09-04 15:30:14