Imaging Systems, Microscopy, and Displays
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Microendoscopes are vital for disease detection and clinical diagnosis. The essential issue for microendoscopes is to achieve minimally invasive and high-resolution observations of soft tissue structures inside deep body cavities. Obviously, the microscope objective is a must with the capabilities of both high lateral resolution in a wide field of view (FOV) and miniaturization in size. Here, we propose a meta-objective, i.e., microscope objective based on cascaded metalenses. The two metalenses, with the optical diameters of 400 μm and 180 μm, respectively, are mounted on both sides of a 500-μm-thick silica film. Sub-micrometer lateral resolution reaches as high as 775 nm in such a naked meta-objective, with monochromatic aberration correction in a 125 μm full FOV and near diffraction limit imaging. Combined with a fiber bundle microscope system, the single cell contour of biological tissue (e.g., water lily leaf) can be clearly observed, compared to the indistinguishable features in other conventional lens-based fiber bundle systems, such as plano–convex and gradient refractive index (GRIN) cases.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.106-115
Instrumentation and Measurements
Chi Man Woo
Optical imaging through or inside scattering media, such as multimode fiber and biological tissues, has a significant impact in biomedicine yet is considered challenging due to the strong scattering nature of light. In the past decade, promising progress has been made in the field, largely benefiting from the invention of iterative optical wavefront shaping, with which deep-tissue high-resolution optical focusing and hence imaging becomes possible. Most of the reported iterative algorithms can overcome small perturbations on the noise level but fail to effectively adapt beyond the noise level, e.g., sudden strong perturbations. Reoptimizations are usually needed for significant decorrelation to the medium since these algorithms heavily rely on the optimization performance in the previous iterations. Such ineffectiveness is probably due to the absence of a metric that can gauge the deviation of the instant wavefront from the optimum compensation based on the concurrently measured optical focusing. In this study, a square rule of binary-amplitude modulation, directly relating the measured focusing performance with the error in the optimized wavefront, is theoretically proved and experimentally validated. With this simple rule, it is feasible to quantify how many pixels on the spatial light modulator incorrectly modulate the wavefront for the instant status of the medium or the whole system. As an example of application, we propose a novel algorithm, the dynamic mutation algorithm, which has high adaptability against perturbations by probing how far the optimization has gone toward the theoretically optimal performance. The diminished focus of scattered light can be effectively recovered when perturbations to the medium cause a significant drop in the focusing performance, which no existing algorithms can achieve due to their inherent strong dependence on previous optimizations. With further improvement, the square rule and the new algorithm may boost or inspire many applications, such as high-resolution optical imaging and stimulation, in instable or dynamic scattering environments.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.202-212
Precise and fast determination of position and orientation, which is normally achieved by distance and angle measurements, has broad applications in academia and industry. We propose a dynamic three-degree-of-freedom measurement technique based on dual-comb interferometry and a self-designed grating-corner-cube (GCC) combined sensor. Benefiting from its unique combination of diffraction and reflection characteristics, the absolute distance, pitch, and yaw of the GCC sensor can be determined simultaneously by resolving the phase spectra of the corresponding diffracted beams. We experimentally demonstrate that the method exhibits a ranging precision (Allan deviation) of 13.7 nm and an angular precision of 0.088 arcsec, alongside a 1 ms reaction time. The proposed technique is capable of precise and fast measurement of distances and two-dimensional angles over long stand-off distances. A system with such an overall performance may be potentially applied to space missions, including in tight formation-flying satellites, for spacecraft rendezvous and docking, and for antenna measurement as well as the precise manufacture of components including lithography machines and aircraft-manufacturing devices.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.243-251
A photonic front-end in the 5G wireless network based on wavelength-division multiplexing optical communication requires low-cost tunable transceivers. By exploiting polymer waveguide Bragg-grating technology, we propose a tunable transceiver consisting of an external cavity tunable laser and a tilted grating tunable filter. In particular, a double-reflection tunable filter provides narrower reflection bandwidth and suppresses undesired mode coupling, improving the side-mode suppression ratio (SMSR) and reducing adjacent-channel crosstalk. By introducing perfluorinated polymers with low birefringence, polarization independence, which is a prerequisite for wavelength filter elements, is secured, and 20 dB bandwidth of 0.69 nm, wavelength tunability over 40 nm, and SMSR of 42 dB are achieved.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.181-186
Lasers and Laser Optics
The requirements for dichroic laser mirrors continue to increase with the development of laser technology. The challenge of a dichroic laser mirror coating is to simultaneously obtain spectral performance with significantly different reflection or transmission properties as well as a high laser-induced damage threshold (LIDT) at two different wavelengths. Traditional dichroic laser mirrors composed of alternating high- and low-refractive-index pure materials often has difficulty achieving excellent spectral performance and high LIDTs at two wavelengths simultaneously. We propose to use a new design with mixture layers and sandwich-like-structure interfaces to meet the challenging requirements. An Al2O3-HfO2 mixture-based dichroic laser mirror, which can be used as a harmonic separator in a fusion-class laser or a pump/signal beam separator in a petawatt-class Ti-sapphire laser system, is experimentally demonstrated using e-beam deposition. The mixture-based dichroic mirror coating shows good spectral performance, fine mechanical property, low absorption, and high LIDT. For the s-polarized 7.7 ns pulses at a wavelength of 532 nm and the p-polarized 12 ns pulses at a wavelength of 1064 nm, the LIDTs are almost doubled. The excellent performance of this new design strategy with mixture layers and sandwich-like-structure interfaces suggests its wide applicability in high-performance laser coating.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.229-236
In this paper, we propose and experimentally demonstrate a vortex random fiber laser (RFL) with a controllable orbital angular momentum (OAM) mode. The topological charge of the vortex RFL can range from -50 to 50 with nearly watt-level output power. A triangular toroidal interferometer is constructed to verify the spiral phase structure of the generated vortex random laser with a special coherence property. Vortex RFLs with fractional topological charge are also performed in this work. As the first demonstration of a vortex RFL with a controllable OAM mode (to the best of our knowledge), this work may not only offer a valuable reference on temporal modulation of a vortex beam and optical field control of an RFL but also provide a potential vortex laser source for applications in imaging, sensing, and communication.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.266-271
Nanophotonics and Photonic Crystals
Photonic crystals have revolutionized the field of optics with their unique dispersion and energy band gap engineering capabilities, such as the demonstration of extreme group and phase velocities, topologically protected photonic edge states, and control of spontaneous emission of photons. Time-variant media have also shown distinct functionalities, including nonreciprocal propagation, frequency conversion, and amplification of light. However, spatiotemporal modulation has mostly been studied as a simple harmonic wave function. Here, we analyze time-variant and spatially discrete photonic crystal structures, referred to as spatiotemporal crystals. The design of spatiotemporal crystals allows engineering of the momentum band gap within which parametric amplification can occur. As a potential platform for the construction of a parametric oscillator, a finite-sized spatiotemporal crystal is proposed and analyzed. Parametric oscillation is initiated by the energy and momentum conversion of an incident wave and the subsequent amplification by parametric gain within the momentum band gap. The oscillation process dominates over frequency mixing interactions above a transition threshold determined by the balance between gain and loss. Furthermore, the asymmetric formation of momentum band gaps can be realized by spatial phase control of the temporal modulation, which leads to directional radiation of oscillations at distinct frequencies. The proposed structure would enable simultaneous engineering of energy and momentum band gaps and provide a guideline for implementation of advanced dispersion-engineered parametric oscillators.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.142-150
Optical and Photonic Materials
Se Gyo Han
Sung Hyuk Kim
Dongyeop X. Oh
Mun Seok Jeong
Understanding the photophysical interactions between the components in organic-inorganic nanocomposites is a key factor for their efficient application in optoelectronic devices. In particular, the photophysical study of nanocomposites based on organic conjugated polymers is rare. We investigated the effect of surface plasmon resonance (SPR) of gold nanoparticles (Au NPs) on the photoluminescence (PL) property of a push-pull conjugated polymer (PBDB-T). We prepared the hybrid system by incorporating poly(3-hexylthiophene)-stabilized Au NPs (P3HT-Au NPs) into PBDB-T. The enhanced and blueshifted PL was observed in the hybrid system compared to PL in a neat PBDB-T system, indicating that the P3HT chains attached to the Au NPs suppressed charge-transfer from PBDB-T to the Au NPs and relayed the hot electrons to PBDB-T (the band-filling effect). This photophysical phenomenon limited the auto-dissociation of PBDB-T excitons. Thus, the radiative recombination of the excitons occurred more in our hybrid system than in the neat system.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.131-141
Inorganic cesium lead halide (CsPbX3, X=Cl, Br, I) nanocrystals (NCs) attract extensive attention because of their excellent optoelectronic performance. However, the classic CsPbX3 NCs suffer from toxicity and instability, which impede their further applications in commercial fields. Here the inorganic lead-free cesium copper chlorine NCs are synthesized by a facile hot-injection method. The blue-emission 3D CsCu2Cl3 and green-emission 0D Cs3Cu2Cl5 NCs are prepared at 70°C and 120°C, respectively, suggesting that the reaction temperature may account for the final components. Owing to the self-trapped exciton effect, the unique optical properties, such as high photoluminescence (PL) quantum yield, broadband emission, large Stokes shift, and long PL decay time, are demonstrated for both cesium copper chlorine NCs. Moreover, highly efficient and stable warm white light-emitting diodes are fabricated with CsCu2Cl3 and Cs3Cu2Cl5 NCs. The study highlights the promising potential for lead-free cesium copper chlorine nanocrystals in nontoxic solid-state lighting applications.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.187-192
Kar Wei Ng
Chiral ligand conjugated transition metal oxide nanoparticles (NPs) are a promising platform for chiral recognition, biochemical sensing, and chiroptics. Herein, we present chirality-based strategy for effective sensing of mercury ions via ligand-induced chirality derived from metal-to-ligand charge transfer (MLCT) effects. The ligand competition effect between molybdenum and heavy metal ions such as mercury is designated to be essential for MLCT chirality. With this know-how, mercury ions, which have a larger stability constant (Kf) than molybdenum, can be selectively identified and quantified with a limit of detection (LOD) of 0.08 and 0.12 nmol/L for D-cysteine and L-cysteine (Cys) capped MoO2 NPs. Such chiral chemical sensing nanosystems would be an ideal prototype for biochemical sensing with a significant impact on the field of biosensing, biological systems, and water research-based nanotoxicology.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.213-221
Nicolas K. Fontaine
Non-mode-selective (NMS) multiplexers (muxes) are highly desirable for coherent power combining to produce a high-power beam with a shaped profile (wavefront synthesis) from discrete, phase-locked emitters. We propose a design for a multi-plane light conversion (MPLC)-based NMS mux, which requires only a few phase masks for coherently combining hundreds of discrete input beams into an output beam consisting of hundreds of Hermite–Gaussian (HG) modes. The combination of HG modes as a base can further construct a beam with arbitrary wavefront. The low number of phase masks is attributed to the identical zero-crossing structure of the Hadamard-coded input arrays and of the output HG modes, enabling the practicality of such devices. An NMS mux supporting 256 HG modes is designed using only seven phase masks, and achieves an insertion loss of -1.6 dB, mode-dependent loss of 4.7 dB, and average total mode crosstalk of -4.4 dB. Additionally, this design, featuring equal power for all input beams, enables phase-only control in coherent power combining, resulting in significant simplifications and fast convergence compared with phase-and-amplitude control.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.88-97
We report a broadband two-dimensional (2D) Kerr and Raman–Kerr frequency comb generation in a silica bottle resonator accounting for azimuthal and axial degrees of freedom and pioneer a method that allows for controlled and reversible switching between a four wave mixing (FWM) state and a stimulated Raman scattering state. The repetition rate of the Raman–Kerr comb is not an integer number of the free spectral range, which spans more than 242 nm with hundreds of teeth. We show that, experimentally and numerically, multiple 2D comb regimes can be selectively accessed via dispersion engineering by exciting different orders of axial modes or modifying the curvature of the axial profile, involving cascaded FWM, Raman lasing, and Raman-assisted FWM. The effect of axial curvature on dispersion is associated with the axial mode number in bottle resonators. Our approach enables dispersion and spectral engineering flexibility in any resonator with localized axial modes.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.171-180
Qian Fan Nie
Qiao Ru Hong
Hao Yang Cui
Tie Jun Cui
Controlling the polarization state of electromagnetic waves is an important topic in microwaves due to the enormous application potential in radar technology and mobile communications. Here, we propose a programmable metasurface based on single-pole double-throw switches to realize multifunctional polarization conversions. A structure of the double-sided metallic pattern is adopted in the metasurface, in which a novel double-pole double-throw hub is achieved to guide the energy direction. Such a mechanism successfully induces multiple transmission channels into the metasurface structure for functional design. By controlling the states of the switches with a field programmable gate array, the x- and y-polarizations of the incident waves can be efficiently modulated into linear co- and cross-polarizations of transmitted waves, suggesting a higher degree of freedom on wave manipulations. The proposed metasurface can be developed as a near-field information encoder to transmit binary coding sequence according to the energy distribution. Character transmissions are realized by programming binary ASCII codes on the transmitted fields. Nine supercells on the metasurface can encode 9-bit binary information in one frame of near-field imaging, which can be switched in real time with high speed. We envision that this work will develop digital coding applications to control the polarization information.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.116-124
Anapole metamaterials have attracted growing attention in recent years due to their unique nonradiating and nontrivial properties. Although anapole modes have been demonstrated in metamaterials with three-dimensional structures, the design and realization of planar anapole metamaterials in a wide frequency range is still a big challenge. Here we propose and experimentally demonstrate a planar anapole metamaterial consisting of dumbbell-shaped apertures on a stainless-steel sheet at terahertz frequencies. The planar metamaterial can generate a resonant transparency in the terahertz spectrum due to the excitation of the anapole mode. Particularly, the frequency of anapole-induced resonant transparency can be tuned easily in the range of 0.15–0.93 THz by simply varying one geometric parameter of the dumbbell apertures. We anticipate that the resonant transparency in planar anapole metamaterials can be potentially used in filters, sensors, or other photonic devices.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.125-130
Alireza R. Rashed
Recent advances in the development of a nanocavity based on a metal–insulator–metal (MIM) structure have provided a great opportunity to enhance the performance of photonic devices. However, the underlying physics behind the emission enhancement obtained from such cavities is under debate. Here, in this work, we designed and investigated MIM nanocavities to reveal the mechanisms for the observed 260-fold photoluminescence enhancement from LDS 798 fluorescent dye. This study provides a pathway to engineer the emission properties of an emitter not only through the enhancement of the Purcell factor but mainly through enhancement of the excitation rate. Our numerical simulations support the experimentally acquired results. We believe an MIM cavity and dye-based hybrid system design based on the revealed enhancement process and structural simplicity, will provide more efficient, lithography free, and low-cost advanced nanoscale devices.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.237-242
Quantum key distribution (QKD) provides a solution for communication of unconditional security. However, the quantum channel disturbance in the field severely increases the quantum bit-error rate, degrading the performance of a QKD system. Here we present a setup comprising silica planar light wave circuits (PLCs), which is robust against the channel polarization disturbance. Our PLCs are based on the asymmetric Mach–Zehnder interferometer (AMZI), integrated with a tunable power splitter and thermo-optic phase modulators. The polarization characteristics of the AMZI PLC are investigated by a novel pulse self-interfering method to determine the operation temperature of implementing polarization insensitivity. Over a 20 km fiber channel with 30 Hz polarization scrambling, our time-bin phase-encoding QKD setup is characterized with an interference fringe visibility of 98.72%. The extinction ratio for the phase states is kept between 18 and 21 dB for 6 h without active phase correction.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.222-228
Optical detectors with single-photon sensitivity and large dynamic range would facilitate a variety of applications. Specifically, the capability of extending operation wavelengths into the mid-infrared region is highly attractive. Here we implement a mid-infrared frequency upconversion detector for counting and resolving photons at 3 μm. Thanks to the spectrotemporal engineering of the involved optical fields, the mid-infrared photons could be spectrally translated into the visible band with a conversion efficiency of 80%. In combination with a silicon avalanche photodiode, we obtained unprecedented performance with a high overall detection efficiency of 37% and a low noise equivalent power of 1.8×10-17 W/Hz1/2. Furthermore, photon-number-resolving detection at mid-infrared wavelengths was demonstrated, for the first time to our knowledge, with a multipixel photon counter. The implemented upconversion detector exhibited a maximal resolving photon number up to 9 with a noise probability per pulse of 0.14% at the peak detection efficiency. The achieved photon counting and resolving performance might open up new possibilities in trace molecule spectroscopy, sensitive biochemical sensing, and free-space communications, among others.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.259-265
A high-dimensional quantum key distribution (QKD), which adopts degrees of freedom of the orbital angular momentum (OAM) states, is beneficial to realize secure and high-speed QKD. However, the helical phase of a vortex beam that carries OAM is sensitive to the atmospheric turbulence and easily distorted. In this paper, an adaptive compensation method using deep learning technology is developed to improve the performance of OAM-encoded QKD schemes. A convolutional neural network model is first trained to learn the mapping relationship of intensity profiles of inputs and the turbulent phase, and such mapping is used as feedback to control a spatial light modulator to generate a phase screen to correct the distorted vortex beam. Then an OAM-encoded QKD scheme with the capability of real-time phase correction is designed, in which the compensation module only needs to extract the intensity distributions of the Gaussian probe beam and thus ensures that the information encoded on OAM states would not be eavesdropped. The results show that our method can efficiently improve the mode purity of the encoded OAM states and extend the secure distance for the involved QKD protocols in the free-space channel, which is not limited to any specific QKD protocol.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.B9-17
We propose a plug-and-play (PnP) method that uses deep-learning-based denoisers as regularization priors for spectral snapshot compressive imaging (SCI). Our method is efficient in terms of reconstruction quality and speed trade-off, and flexible enough to be ready to use for different compressive coding mechanisms. We demonstrate the efficiency and flexibility in both simulations and five different spectral SCI systems and show that the proposed deep PnP prior could achieve state-of-the-art results with a simple plug-in based on the optimization framework. This paves the way for capturing and recovering multi- or hyperspectral information in one snapshot, which might inspire intriguing applications in remote sensing, biomedical science, and material science. Our code is available at: https://github.com/zsm1211/PnP-CASSI.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.B18-29
Compressed ultrafast photography (CUP) is the fastest single-shot passive ultrafast optical imaging technique, which has shown to be a powerful tool in recording self-luminous or non-repeatable ultrafast phenomena. However, the low fidelity of image reconstruction based on the conventional augmented-Lagrangian (AL) and two-step iterative shrinkage/thresholding (TwIST) algorithms greatly prevents practical applications of CUP, especially for those ultrafast phenomena that need high spatial resolution. Here, we develop a novel AL and deep-learning (DL) hybrid (i.e., AL+DL) algorithm to realize high-fidelity image reconstruction for CUP. The AL+DL algorithm not only optimizes the sparse domain and relevant iteration parameters via learning the dataset but also simplifies the mathematical architecture, so it greatly improves the image reconstruction accuracy. Our theoretical simulation and experimental results validate the superior performance of the AL+DL algorithm in image fidelity over conventional AL and TwIST algorithms, where the peak signal-to-noise ratio and structural similarity index can be increased at least by 4 dB (9 dB) and 0.1 (0.05) for a complex (simple) dynamic scene, respectively. This study can promote the applications of CUP in related fields, and it will also enable a new strategy for recovering high-dimensional signals from low-dimensional detection.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.B30-37
Binh Thi Thanh Nguyen
Patricia Yang Liu
We demonstrate a smart sensor for label-free multicomponent chemical analysis using a single label-free ring resonator to acquire the entire resonant spectrum of the mixture and a neural network model to predict the composition for multicomponent analysis. The smart sensor shows a high prediction accuracy with a low root-mean-squared error ranging only from 0.13 to 2.28 mg/mL. The predicted concentrations of each component in the testing dataset almost all fall within the 95% prediction bands. With its simple label-free detection strategy and high accuracy, the smart sensor promises great potential for multicomponent analysis applications in many fields.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.B38-44
Recently, all-inorganic halide perovskites have received enormous attention because of their excellent optoelectronic properties. Among them, the power conversion efficiency (PCE) of all-inorganic halide perovskite solar cells has made rapid progress in the last few years. However, understanding the intrinsic physical nature of halide perovskites, especially the dynamic process of photo-generated carriers, is a key for improving the PCE. In this review, we introduced and summarized the photoluminescence (PL) technique used to explore the carrier dynamic process in all-inorganic halide perovskites. Several physical models were proposed to investigate the dynamic parameters, i.e., recombination lifetime and diffusion length, by analyzing the steady-state PL as well as the time-resolved PL spectra. We also discussed the distinction of PL spectral behavior between bulk halide perovskite samples and those grown with transport layers due to the participation of different dominant dynamic paths. Finally, we briefly described some other optical techniques reported to study the relevant physical properties of all-inorganic halide perovskites.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.151-170
Optical clocks with an unprecedented accuracy of 10-18 promise innovations in precision spectroscopy and measurement. To harness the full power of optical clocks, we need optical frequency synthesizers (OFSs) to accurately convert the stabilities and accuracies of optical clocks to other desired frequencies. This work demonstrates such an OFS referenced to an ytterbium optical clock. The OFS is based on an optical frequency comb phase-locked to a commercial rubidium microwave clock; in this way most combs can operate robustly. Despite comb frequency instability at 10-11, the synthesis noise and uncertainty reach 6×10-18 (1 s) and 5×10-21, respectively, facilitating frequency synthesis of the best optical clocks. In the OFS, the coherence of the OFS internal oscillator at 1064 nm is accurately transferred to a 578 nm laser for resolving the hertz-level-linewidth ytterbium clock transition (unaffected by megahertz-linewidth comb lines) and faithfully referencing the OFS to an ytterbium optical clock.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.98-105
Laser absorption spectroscopy (LAS) has become the most widely used laser spectroscopic technique for gas detection due to its capability of accurate quantification and straightforward operation. However, since resolving weak absorption and averting over-absorption are always mutually exclusive, the dynamic range of the LAS-based gas sensor is limited and insufficient for many applications in fundamental study and industry. To overcome the limitation on the dynamic range, this article reports optical pathlength (OPL) multiplexed absorption spectroscopy using a gas cell having multiple internal reflections. It organically fuses together the transmission and reflection operation modes: the former directly uses the entire OPL of the gas cell, while the latter interrogates different internal short OPLs by optical interferometry, yielding >100-fold OPL variation. The achieved dynamic range is more than 6 orders of magnitude that surpasses other LAS techniques by 2–3 orders of magnitude. The proposed method promotes a novel way for the development of large-dynamic-range spectroscopic gas sensors for fundamental studies and industrial applications.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.193-201
Surface Optics and Plasmonics
Ho Wai Howard Lee
The direct interfacing of photonic crystal fiber to a metallic nanoantenna has widespread application in nanoscale imaging, optical lithography, nanoscale lasers, quantum communication, in vivo sensing, and medical surgery. We report on the fabrication of a needle-shaped plasmonic nanoantenna on the end facet of a photonic crystal fiber using electron-beam-induced evaporation of platinum. We demonstrate the coupling of light from the fiber waveguide mode to the subwavelength nanoantenna plasmonic mode focusing down to the apex of the plasmonic needle using a polarization-resolved far-field side-scatter imaging technique. Our work provides an important step toward widespread application of optical fibers in nearfield spectroscopic techniques such as tip-enhanced Raman and fluorescence microscopy, single-photon excitation and quantum sensors, nanoscale optical lithography, and lab-on-fiber devices.
PDF全文   HTML全文 , 2021年第9卷第2期 pp.252-258