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Light from van der Waals quantum tunneling devices
摘要： The understanding of and control over light emission from quantum tunneling has challenged researchers for more than four decades due to the intricate interplay of electrical and optical properties in atomic scale volumes. Here we introduce a device architecture that allows for the disentanglement of electronic and photonic pathways—van der Waals quantum tunneling devices. The electronic properties are defined by a stack of two-dimensional atomic crystals whereas the optical properties are controlled via an external photonic architecture. In van der Waals heterostructures made of gold, hexagonal boron nitride and graphene we find that inelastic tunneling results in the emission of photons and surface plasmon polaritons. By coupling these heterostructures to optical nanocube antennas we achieve resonant enhancement of the photon emission rate in narrow frequency bands by four orders of magnitude. Our results lead the way towards a new generation of nanophotonic devices that are driven by quantum tunneling.
关键词： van der Waals heterostructures,inelastic electron tunneling,nanophotonics,light emission,quantum tunneling,optical antennas
更新于2025-09-19 17:15:36
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Effects of near-field electromagnetic coupling in dimers of nanoparticles with a silver core and a J-aggregate dye shell
摘要： We report a theoretical study of the plasmon – exciton coupling effect on the absorption spectra of pairs of closely spaced double-layer hybrid nanoparticles consisting of a metallic core and a J-aggregate dye shell. The effect of frequency conversion of plasmonic lines due to the near-field interaction between plasmons and Frenkel excitons of the organic shell is demonstrated. The effect leads to the appearance of additional spectral lines in the long-wavelength part of the spectrum of the system of hybrid particles. The shapes and the relative intensities of the additional lines exactly reproduce the specific features of the original spectrum of plasmonic absorption bands in uncoated metallic nanoparticles. The discovered phenomenon can be used to design new types of high-sensitivity nanosensors, based on plasmon – exciton effects and principles of near-field optics.
关键词： near-field electromagnetic coupling,nanophotonics,Frenkel excitons,dimers of metalorganic nanoparticles,plasmon – exciton interaction,molecular J-aggregates,localised plasmons,absorption spectra
更新于2025-09-19 17:15:36
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Active control of anapole states by structuring the phase-change alloy Ge2Sb2Te5
摘要： High-index dielectric nanoparticles supporting a distinct series of Mie resonances have enabled a new class of optical antennas with unprecedented functionalities. The great wealth of multipolar responses has not only brought in new physical insight but also spurred practical applications. However, how to make such a colorful resonance palette actively tunable is still elusive. Here, we demonstrate that the structured phase-change alloy Ge2Sb2Te5 (GST) can support a diverse set of multipolar Mie resonances with active tunability. By harnessing the dramatic optical contrast of GST, we realize broadband (Δλ/λ ~ 15%) mode shifting between an electric dipole resonance and an anapole state. Active control of higher-order anapoles and multimodal tuning are also investigated, which make the structured GST serve as a multispectral optical switch with high extinction contrasts (>6 dB). With all these findings, our study provides a new direction for realizing active nanophotonic devices.
关键词： active tuning,nanophotonics,phase-change materials,anapole states,GST,Mie resonances
更新于2025-09-19 17:15:36
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Metallic Carbon Nanotube Nanocavities as Ultra-compact and Low-loss Fabry-Perot Plasmonic Resonators
摘要： Plasmonic resonators enable deep subwavelength manipulation of light matter interactions and have been intensively studied both in fundamental physics as well as for potential technological applications. While various metallic nanostructures have been proposed as plasmonic resonators, their performances are rather limited at mid- and far-infrared wavelengths. Recently, highly-confined and low-loss Luttinger liquid plasmons in metallic single walled carbon nanotubes (SWNTs) have been observed at infrared wavelengths. Here, we tailor metallic SWNTs into ultraclean nanocavities by advanced scanning probe lithography and investigate plasmon modes in these individual nanocavities by infrared nano-imaging. The dependence of mode evolutions on cavity length and excitation wavelength can be captured by a Fabry-Perot resonator model of a plasmon nanowaveguide terminated by highly reflective ends. Plasmonic resonators based on SWNT nanocavities approach the ultimate plasmon confinement limit and open the door to the strong light-matter coupling regime, which may enable various nanophotonic applications.
关键词： Plasmonic nanocavity,Carbon nanotubes,Nanophotonics,Infrared nano-imaging
更新于2025-09-19 17:13:59
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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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All-optical InAsP/InP nanowire switches integrated in a Si photonic crystal
摘要： We report the successful demonstration of all-optical switching using a sub-wavelength InP/InAsP nanowire integrated in a silicon photonic crystal at telecommunication wavelengths. In this work, we employed two different hybrid nanowire cavities based on an air-trench in photonic crystals. These hybrid cavities have the advantages of both material functionality of III-V material and the low propagation loss of the silicon waveguide. The nanowire induced line-defect photonic crystal cavity shows a Q-factor of 25000, higher than the hybrid systems we previously demonstrated. The switching time is 150 ps, which is among the fastest nanowire switches reported. We found that the switching time was clearly dependent on the Q-factor. From measurements performed while changing pump power, we have estimated the switching energy to be a few hundred femtojoules. This value is lower than that of a reference silicon photonic crystal cavity without a nanowire and an air trench under the same pumping condition. This indicates that the InP/InAsP nanowire integrated in a silicon photonic crystal has potential to contribute to reducing the switching energy.
关键词： all-optical switch,AFM manipulation,nanophotonics,photonic crystal,nanowire,photonic integrated circuits
更新于2025-09-19 17:13:59
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Progress of Photodetectors Based on the Photothermoelectric Effect
摘要： High-performance uncooled photodetectors operating in the long-wavelength infrared and terahertz regimes are highly demanded in the military and civilian fields. Photothermoelectric (PTE) detectors, which combine photothermal and thermoelectric conversion processes, can realize ultra-broadband photodetection without the requirement of a cooling unit and external bias. In the last few decades, the responsivity and speed of PTE-based photodetectors have made impressive progress with the discovery of novel thermoelectric materials and the development of nanophotonics. In particular, by introducing hot-carrier transport into low-dimensional material–based PTE detectors, the response time has been successfully pushed down to the picosecond level. Furthermore, with the assistance of surface plasmon, antenna, and phonon absorption, the responsivity of PTE detectors can be significantly enhanced. Beyond the photodetection, PTE effect can also be utilized to probe exotic physical phenomena in spintronics and valleytronics. Herein, recent advances in PTE detectors are summarized, and some potential strategies to further improve the performance are proposed.
关键词： thermoelectrics,low-dimensional materials,photothermoelectric effect,photodetectors,nanophotonics
更新于2025-09-19 17:13:59
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[IEEE ESSDERC 2019 - 49th European Solid-State Device Research Conference (ESSDERC) - Cracow, Poland (2019.9.23-2019.9.26)] ESSDERC 2019 - 49th European Solid-State Device Research Conference (ESSDERC) - Suspended Antenna-Coupled Nanothermocouple Array for Long-Wave Infrared Detection
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-field 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 first 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： optical antenna,Adjoint method,computational electromagnetics,heat-assisted magnetic recording,near-field transducer (NFT),management,thermal,nanophotonics,plasmonics,gradient methods,inverse problem,optimization,hard disks
更新于2025-09-19 17:13:59
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Scaling Resistance in Nanophotonics-Enabled Solar Membrane Distillation
摘要： This study compares the scaling behavior of membrane distillation (MD) with that of nanophotonics-enabled solar membrane distillation (NESMD). Previous research has shown that NESMD, due to its localized surface heating driven by photothermal membrane coatings, is an energy-efficient system for off-grid desalination; however, concerns remained regarding the scaling behavior of self-heating surfaces. In this work, bench-scale experiments were performed, using model brackish water, to compare the scaling propensity of NESMD with MD. The results showed NESMD to be highly resistant to scaling; a three times higher salt concentration factor (c/c0) was achieved in NESMD compared to MD without any decline in flux. Analyses of the scaling layer on NESMD membranes revealed that salt deposition was 1/4 of that observed for MD. Scaling resistance in NESMD is attributed to its lower operating temperature, which increases the solubility of common scalants and decreases salt precipitation rates. Precipitation kinetics measurements revealed an order of magnitude faster precipitation under heated conditions (62 °C, k = 8.7 × 10?2 s?1) compared to ambient temperature (22 °C, k = 7.1 × 10?3 s?1). These results demonstrate a distinct advantage of NESMD over MD for the treatment of high scaling potential water, where scaling is a barrier to high water recovery.
关键词： nanophotonics-enabled solar membrane distillation,photothermal membrane coatings,scaling resistance,desalination,membrane distillation
更新于2025-09-19 17:13:59
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Silicon ring resonator electro-optical modulator utilizing epsilon-near-zero characteristics of indium tin oxide
摘要： One crucial component in optical communication systems is the optical modulator. It links between the electric and optical domains as it transforms the electric signal into an optical stream. Electro-optical modulation is a very popular scheme. Recently, indium tin oxide (ITO) has been intensively used in optical modulators due to its epsilon-near-zero characteristics. A silicon electro-optic ring resonator modulator is proposed in terms of the outspread application of ITO. An extinction ratio of about 14 dB as well as an insertion loss of 0.075 dB are achieved at a standard telecommunication wavelength of 1.55 microns. The design has low losses, high efficiency, and compact size.
关键词： silicon nanophotonics,ring resonators,indium tin oxide,electro-optical modulators,integrated photonics
更新于2025-09-19 17:13:59