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Investigation of optical fiber-tip probes for common and ultrafast SERS
摘要： In this study, we performed a three-dimensional computational experiment on ultrashort pulse propagation in an optical fiber-tip probe that is decorated with gold nanoparticles (NPs) using a constant structure for the probe’s dielectric taper and different spatial configurations of the gold nanoparticles. Interestingly, a hot spot with the highest amplitude of the electric field was found not along the same chain of the NPs but between terminal NPs of neighboring chains of NPs at the probe’s tip (the amplitude of the electric field in the hot spots between the NPs along the same chain was of the order of 101, while that between terminal NPs of neighboring chains was of the order of 103). We eventually identified a configuration with only six terminal nanoparticles (Config4) which is characterized by the highest electric field amplitude enhancement and can provide the highest spatial resolution in the SERS interrogation of an object of interest. The ultrashort temporal responses of the hot spots for all configurations exhibited relatively high pulse elongation (relative elongation was greater than 4.3%). At the same time, due to the reflection of the incident pulse and consequent interference, the temporal responses of most hot spots contained several peaks for all configurations except for the optimum Config4. Nonetheless, the ultrashort temporal responses of all hot spots for Config4 were characterized by a single peak but with a relatively large pulse elongation (relative elongation was 234.1%). The results indicate that further examination of this new structure of a nanoparticles-coated optical fiber-tip probe with only six terminal NPs may provide attractive characteristics for its practical applications.
关键词： gold nanoparticles,femtosecond pulse,optical fiber-tip probe,ultrafast nanophotonics.,surface-enhanced Raman spectroscopy,temporal response
更新于2025-09-23 15:19:57
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Optoplasmonics: basic principles and applications
摘要： Plasmonic and photonic elements often have complementary optical properties, motivating the development of ‘optoplasmonic’ hybrid systems in which the photonic and plasmonic elements can synergistically interact. The overall goal in the design of optoplasmonic structures is to overcome the limitations of the individual building blocks or to generate entirely new properties that reach beyond what is possible with conventional photonic or plasmonic structures. After providing a brief introduction into the relevant optical properties of plasmonic and photonic building blocks, this manuscript reviews optoplasmonic architectures that contain plasmonic nanoantennas embedded in a de?ned photonic environment generated by discrete dielectric nanoparticles (NPs), microcavities, waveguides, or photonic crystals, as well as all-metal NP or metal/dielectric NP hybrid arrays in which diffracted modes interact with the plasmons of metal NPs. The fundamental working principles of these optoplasmonic systems are analyzed and selected applications and fabrication strategies are discussed.
关键词： metamaterials,metasurface,sensing,hybrid materials,high refractive index dielectrics,plasmonics,nanophotonics
更新于2025-09-23 15:19:57
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Plasmonic colored nanopaper: a potential preventive healthcare tool against threats emerging from uncontrolled UV exposure
摘要： Preventive healthcare is crucial to hinder or delay the onset of disease, furthermore it contributes to healthy and productive lifestyles and saves resources allocated to public health. Herein, we explore how the plasmonic coupling of silver and gold nanoparticles embedded within nanopaper allows for potential preventive healthcare tools based on a change in plasmonic color. Particularly, we selected UV radiation exposure as a potential threat to health to be monitored via plasmonic colored nanopaper (PCN). Uncontrolled UV radiation exposure is not only known to provoke epidermal damage, but also to trigger leaching of hazardous compounds from polycarbonate containers. In this context, we engineered UV-responsive PCN devices whose sensing mechanism is based on UV photodegradation of silver nanoparticles. Since absorbance and scattering of metal nanoparticles strongly depend on their size and inter-particle distance, the resulting PCN detectors are able to warn of the potential UV radiation-induced threat via a visually observable plasmonic color change with a yellowish/reddish transition. Epidermal experiments with tattoo-like PCN devices prove the resulting detectors can change in color upon safe dose of sun exposure. Moreover, PCN detectors stuck on polycarbonate containers also change in color after moderate sun exposure. This cost-effective and lightweight nanophotonic device leads to a versatile preventive healthcare tool.
关键词： smart packaging,nanoplasmonics,wearable devices,nanocellulose,nanophotonics
更新于2025-09-23 15:19:57
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Deep learning enabled inverse design in nanophotonics
摘要： Deep learning has become the dominant approach in artificial intelligence to solve complex data-driven problems. Originally applied almost exclusively in computer-science areas such as image analysis and nature language processing, deep learning has rapidly entered a wide variety of scientific fields including physics, chemistry and material science. Very recently, deep neural networks have been introduced in the field of nanophotonics as a powerful way of obtaining the nonlinear mapping between the topology and composition of arbitrary nanophotonic structures and their associated functional properties. In this paper, we have discussed the recent progress in the application of deep learning to the inverse design of nanophotonic devices, mainly focusing on the three existing learning paradigms of supervised-, unsupervised-, and reinforcement learning. Deep learning forward modelling i.e. how artificial intelligence learns how to solve Maxwell’s equations, is also discussed, along with an outlook of this rapidly evolving research area.
关键词： forward modelling,inverse design,nanophotonics,artificial intelligence,metamaterials,machine learning
更新于2025-09-23 15:19:57
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Long-Range Single-Molecule F??rster Resonance Energy Transfer between Alexa Dyes in Zero-Mode Waveguides
摘要： Zero-mode waveguide (ZMW) nano-apertures milled in metal films were proposed to improve the F?rster resonance energy transfer (FRET) efficiency and enable single-molecule FRET detection beyond the 10 nm barrier, overcoming the restrictions of diffraction-limited detection in a homogeneous medium. However, the earlier ZMW demonstrations were limited to the Atto 550?Atto 647N fluorophore pair, asking the question whether the FRET enhancement observation was an artifact related to this specific set of fluorescent dyes. Here, we use Alexa Fluor 546 and Alexa Fluor 647 to investigate single-molecule FRET at large donor?acceptor separations exceeding 10 nm inside ZMWs. These Alexa fluorescent dyes feature a markedly different chemical structure, surface charge, and hydrophobicity as compared to their Atto counterparts. Our single molecule data on Alexa 546?Alexa 647 demonstrate enhanced FRET efficiencies at large separations exceeding 10 nm, extending the spatial range available for FRET and confirming the earlier conclusions. By showing that the FRET enhancement inside a ZMW does not depend on the set of fluorescent dyes, this report is an important step to establish the relevance of ZMWs to extend the sensitivity and detection range of FRET, while preserving its ability to work on regular fluorescent dye pairs.
关键词： single-molecule,nanophotonics,FRET,Alexa Fluor,Zero-mode waveguide
更新于2025-09-23 15:19:57
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On-chip single-mode CdS nanowire laser
摘要： By integrating a free-standing cadmium sulfide (CdS) nanowire onto a silicon nitride (SiN) photonic chip, we demonstrate a highly compact on-chip single-mode CdS nanowire laser. The mode selection is realized using a Mach-Zehnder interferometer (MZI) structure. When the pumping intensity exceeds the lasing threshold of 4.9 kW/cm2, on-chip single-mode lasing at ~518.9 nm is achieved with a linewidth of 0.1 nm and a side-mode suppression ratio of up to a factor of 20 (13 dB). The output of the nanowire laser is channelled into an on-chip SiN waveguide with high efficiency (up to 58%) by evanescent coupling, and the directional coupling ratio between the two output ports can be varied from 90 to 10% by predesigning the coupling length of the SiN waveguide. Our results open new opportunities for both nanowire photonic devices and on-chip light sources and may pave the way towards a new category of hybrid nanolasers for chip-integrated applications.
关键词： Mach-Zehnder interferometer,single-mode lasing,nanowire laser,on-chip nanophotonics,silicon nitride waveguide
更新于2025-09-23 15:19:57
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The Integration of Photonic Crystal Waveguides with Atom Arrays in Optical Tweezers
摘要： Integrating nanophotonics and cold atoms has drawn increasing interest in recent years due to diverse applications in quantum information science and the exploration of quantum many-body physics. For example, dispersion-engineered photonic crystal waveguides (PCWs) permit not only stable trapping and probing of ultracold neutral atoms via interactions with guided-mode light, but also the possibility to explore the physics of strong, photon-mediated interactions between atoms, as well as atom-mediated interactions between photons. While diverse theoretical opportunities involving atoms and photons in 1D and 2D nanophotonic lattices have been analyzed, a grand challenge remains the experimental integration of PCWs with ultracold atoms. Here, an advanced apparatus that overcomes several significant barriers to current experimental progress is described, with the goal of achieving strong quantum interactions of light and matter by way of single-atom tweezer arrays strongly coupled to photons in 1D and 2D PCWs. Principal technical advances relate to efficient free-space coupling of light to and from guided modes of PCWs, silicate bonding of silicon chips within small glass vacuum cells, and deterministic, mechanical delivery of single-atom tweezer arrays to the near fields of photonic crystal waveguides.
关键词： atoms and nanophotonics,quantum simulation,quantum dielectrics,quantum information science
更新于2025-09-23 15:19:57
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Pure Metal-Organic Framework Microlasers with Controlled Cavity Shapes
摘要： Metal-organic frameworks (MOF) are an emerging kind of laser material, yet remains a challenge in the controlled fabrication of crystal nanostructures with desired morphology for tuning their optical microcavities. Herein, the shape-engineering of pure MOF microlasers was demonstrated based on the coordination mode-tailored method. The one-dimensional (1D) microwires and 2D microplates were selectively fabricated through changing the HCl concentration to tailor the coordination modes. Both the single-crystalline microwires and microplates with strong optical confinement functioned as low-threshold MOF microlasers. Moreover, distinct lasing behaviors of 1D and 2D MOF microcrystals confirm a typical shape-dependent microcavity effect: 1D microwires serve as Fabry-Pérot (FP) resonators, and 2D microplates lead to the whispering-gallery-mode (WGM) microcavities. These results provide a special pathway for the exploitation of MOF-based micro/nanolasers with on-demand functions.
关键词： metal-organic framework,microcavity effect,microlasers,nanophotonics
更新于2025-09-23 15:19:57
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Nonlinear optical properties of colloidal CdSe/ZnS quantum dots in PMMA
摘要： The colloidal CdSe/ZnS quantum dots (QDs) in the PMMA polymer film with different QDs concentrations were fabricated. The influence of QDs concentration and excitation pump energy on nonlinear optical (NLO) properties of PMMA capped CdSe/ZnS QDs was investigated by the Z-scan technique with nanosecond laser pulses in the near-infrared spectral band. A large effective nonlinear absorption coefficient (βeff～?10?13 esu) due to the saturable absorption was observed. It was found that the appropriate concentration could lead to the reinforcement of NLO effect. In addition, the impact of the excitation energy on the nonlinear refractive index n2, real and imaginary parts of the third-order nonlinear optical susceptibility was also performed. This study involving the light–matter interactions in the colloidal quantum dots will benefit potential NLO-based applications of optoelectronics, optical modulation and photonics.
关键词： nanophotonics,semiconductor colloidal quantum dots,impact behavior,Z-scan technique,nonlinear optical (NLO) properties
更新于2025-09-23 15:19:57
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Integrated Raman Laser: A Review of the Last Two Decades
摘要： Important accomplishments concerning an integrated laser source based on stimulated Raman scattering (SRS) have been achieved in the last two decades in the fields of photonics, microphotonics and nanophotonics. In 2005, the first integrated silicon laser based upon SRS was realized in the nonlinear waveguide. This breakthrough promoted an intense research activity addressed to the realization of integrated Raman sources in photonics microstructures, like microcavities and photonics crystals. In 2012, a giant Raman gain in silicon nanocrystals was measured for the first time. Starting from this impressive result, some promising devices have recently been realized combining nanocrystals and microphotonics structures. Of course, the development of integrated Raman sources has been influenced by the trend of photonics towards the nano-world, which started from the nonlinear waveguide, going through microphotonics structures, and finally coming to nanophotonics. Therefore, in this review, the challenges, achievements and perspectives of an integrated laser source based on SRS in the last two decades are reviewed, side by side with the trend towards nanophotonics. The reported results point out promising perspectives for integrated micro- and/or nano-Raman lasers.
关键词： nonlinear waveguide,lasers,microphotonics,nanophotonics,stimulated Raman scattering,optical microcavity,photonics crystals,nonlinear optics,nanocrystals
更新于2025-09-23 15:19:57