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Low-cost large-area chirality meta-devices (CMDs) with adjustable optical chirality are of great interest for polarization-sensitive imaging, stereoscopic display, enantioselectivity analysis, and catalysis. Currently, CMDs with adjusted chiroptical responses in the mid-infrared to terahertz band have been demonstrated by exploiting photocarriers of silicon, pressure, and phase-change of GSTs but are still absent in the visible band, which in turn limits the development of chiral nanophotonic devices. Herein, by employing a phase-change material (Sb2S3), we present a protocol for the fabrication of wafer-scale visible-band enantiomeric CMDs with handedness, spectral, and polarization adjustability. As measured by circular dichroism, the chirality signs of CMDs enantiomers can be adjusted with Sb2S3 from amorphous to crystalline, and the chirality resonance wavelength can also be adjusted. Our results suggest a new type of meta-devices with adjustable chiroptical responses that may potentially enable a wide range of chirality nanophotonic applications including highly sensitive sensing and surface-enhanced nanospectroscopy.

Nearly thirty years ago, Specht et al. proposed a new optical near-field microscope based on the interaction of surface plasmons and a sharp metal tip. Since then, the tip-based plasmonic nanofocusing has been widely studied. When the tip-based plasmonic nanofocusing integrated with scanning probe microscopy, it not only forms highly localized enhanced electric field to boost the spectral signal but also simultaneously provides morphological information. These amazing properties provide a new detection method to understand the nano-world, including spatial structures of chemicals and physical, electronic and catalytic properties of substance. Upon growing demand for background-free nanofocusing, more and more attention is being drawn to developing new technologies for it. Hitherto, owing to the salient properties, tip-based background-free nanofocusing have tremendous advanced applications such as ultrafast optics, nonlinear optics, and even electron emission. This article reviews the historical developments from fundamentals to the techniques for tip-based plasmonic nanofocusing and then to their advanced applications.

We theoretically present the selective remote-excitation of the gap mode in the silver nanowire-nanoparticle (Ag NW-NP) system based on the excitation of the ±1-order chiral surface plasmonic polaritons (SPPs) modes, which have the crescent-shaped transverse intensity distributions and the helical propagation traces. When the gap mode at junction between the Ag-NW and the Ag-NP is excited via the +1-order chiral SPPs mode, the −1-order chiral SPP mode cannot effectively excite the gap mode, because the propagation traces of the ±1-order spiral SPPs modes have complementary intensity distributions. This selective remote-excitation method may be used in the nanowire photonics and nano-optical spectroscopy.

Acute myocardial infarction is characterized by ischaemia‐induced cardiomyocyte apoptosis, in which the endoplasmic reticulum (ER) stress plays an important role. The fatty acid‐binding protein‐4 (FABP4) has been implicated in regulating ER stress and apoptosis. Yet, whether FABP4 is involved in modulating cardiomyocyte apoptosis remains unclarified. By applying an in vitro model of hypoxia‐induced apoptosis of H9c2 cardiomyocytes, we found that FABP4 expression was elevated upon hypoxia stimulation, which was further demonstrated to be transcriptionally activated by the hypoxia‐inducible factor 1a (HIF‐1α). In addition, the pharmacological inhibition of FABP4 with BMS309403 protected against hypoxia‐induced apoptosis in cardiomyocytes, indicating that FABP4 induction is detrimental for cardiomyocyte survival under hypoxic condition. Moreover, BMS309403 attenuated ER stress in cardiomyocytes exposed to hypoxia, which, however, was reversed by tunicamycin, an ER stress activator. More importantly, the protective effect of BMS309403 on cardiomyocytes vanished in the presence of tunicamycin. Thus, these observations establish that FABP4 inhibitor BMS309403 reduces hypoxia‐induced cardiomyocyte apoptosis through attenuating excessive ER stress, implying that FABP4 inhibition may be of clinical benefit for MI treatment.

The interplay of Mie’s multipole resonances provides a huge opportunity for discovering new phenomena in nanophotonics and developing nanophotonic devices of new functionalities. One of the keys to...

We present a method for achieving the cylindrical vector beams (CVBs) and optical vortex generation in a solid-core ring fiber (SCRF) by using an acoustically induced fiber grating (AIFG). Theoretical analysis shows that the SCRF can introduce a refractive index difference of ∼10–5 between the first group of adjacent high-order degenerate vector modes. In the experiment, the transmission spectra of AIFG constructed with the SCRF depicts three separate resonance peaks with 3-dB bandwidth and resonance wavelength interval of 0.16 and 2.5 nm, respectively, revealing that the high-order degenerate vector modes have been effectively separated. On the basis of the separation of the degenerate vector mode, the CVBs and the ±1-order optical vortex are further experimentally generated at three separate wavelengths using the AIFG.

Graphene supports both transverse magnetic and electric modes of surface polaritons due to the intraband and interband transition properties of electrical conductivity. Here, we reveal that perfect excitation and attenuation-free propagation of surface polaritons on graphene can be achieved under the condition of optical admittance matching. With both vanished forward and backward far-field radiation, incident photons are fully coupled to surface polaritons. This requires an exact match between the admittance difference of sandwiching media and the conductivity of graphene, resulting in no decay of propagating surface polaritons. The dispersion relation has a completely different line shape for structures that support compared to those that do not support admittance matching. This work promotes complete comprehension of the excitation and propagation behaviors of graphene surface polaritons and may further inspire ideas for research on surface waves on two-dimensional materials.

Plasmonic tip nanofocusing has widely been applied in tip-enhanced Raman spectroscopy, optical trapping, nonlinear optics, and super-resolution imaging due to its capability of high local field enhancement. In this work, a substrate with a circular nanocavity is proposed to enhance the nanofocusing and optical trapping characteristics of the plasmonic tip. Under axial illumination of a tightly focused radial polarized beam, the circular nanohole etched on a metallic substrate can form a nanocavity to induce an interference effect and further enhance the electric field intensity. When a plasmonic tip is placed closely above such a substrate, the electric field intensity of the gap-plasmon mode can further be improved, which is 10 folds stronger than that of the conventional gap-plasmon mode. Further analysis reveals that the enhanced gap-plasmon mode can significantly strengthen the optical force exerted on a nanoparticle and stably trap a 4-nm-diameter dielectric nanoparticle. Our proposed method can improve the performance of tip-enhanced spectroscopy, plasmonic tweezers and extend their applications. We anticipate that our methods allow simultaneously manipulating and characterizing single nanoparticles in-situ.

This study aimed to analyze the early and mid-term outcomes of aortic valve replacement with bovine pericardium in the treatment of aortic valve regurgitation.From January 2015 to March 2018, 36 patients (19 men; mean ± standard deviation [SD] age, 46.70 ± 16.60 years) underwent aortic valve replacement with bovine pericardium. The bovine pericardium was intraoperatively measured and shaped using an Ozaki template, according to the shape and size of the individual patient's aortic valve leaflets. Additional procedures were performed, including ventricular septal defect repair in 5 cases, mitral valve reconstruction in 6 cases, tricuspid valve reconstruction in 6 cases, and coronary artery bypass grafting in 3 cases.There were no perioperative deaths. One elderly patient with postoperative respiratory failure recovered after symptomatic treatment. One patient with frequent ventricular tachycardia after intraoperative cardiac re-jump underwent intra-aortic balloon counterpulsation (IABP), and the IABP device was successfully removed on the second postoperative day. Within the first 6 months of follow-up, there were no death events, no reoperation events, and no additional thromboembolic events. Follow-up echocardiography was performed for 6 months, with average left ventricular ejection fraction of 62.01 ± 3.21%, mean transvalvular pressure gradient of 11.17 ± 4.90 mmHg, and mean aortic valve velocity of 1.60 ± 0.58 m/s. Compared with the preoperative transthoracic echocardiography findings, the results at the six-month follow-up were statistically significant (P < 0.05). Mild aortic valve regurgitation occurred in 2 patients (5.56%), whereas other patients had no or only minimal aortic valve regurgitation (n = 34, 94.44%). Moderate aortic valve regurgitation occurred in one patient at 9 months after the initial operation. This was found to be due to infective endocarditis, and a biological valve was finally implanted.Aortic valve replacement with bovine pericardium in the treatment of aortic valve regurgitation is feasible, and good early and mid-term results are achieved. Long-term results need to be followed up in the future.

Tip-enhanced Raman spectroscopy (TERS) is a very useful method to achieve label-free and super-resolution imaging, and the plasmonic tip nanofocusing plays a decisive role for TERS performance. Here, we present a method to enhance the nanofocusing characteristic of a plasmonic tip integrated in a grating near the tip apex. Simulation results show that the grating near the tip apex can significantly improve the electric field intensity of the nanofocusing field compared with a conventional bare tip, under axial excitation of a tightly focused radial vector beam. The electric field enhancement characteristic is quantified in relation with the groove number of grating, excitation wavelength, period of grating, and numerical aperture of the micro-objective (MO). These simulation results could be a good reference to fabricate a plasmonic tip for TERS applications, which is an effective way to promote the development of tip-enhanced near-field optical microscopy.

We theoretically present the nanofocusing of the metal-coated fiber tip under internal excitation of the radial vector beam within visible band based on the finite difference time domain (FDTD) analysis. The electric field intensity enhancement factor of the localized surface plasmons (LSP) mode at the tip apex is quantitatively shown in relation with incident wavelength, coating material, conical angle of tip, and coating film thickness/length. Specially, the evolution of fiber radial vector mode to surface mode with respect to the radius of metal-coated fiber tip is calculated under typical excitation wavelengths of 633 nm and 785 nm. Furthermore, the reason of the tip eliminating far-field background signal is explained, and the transverse electric field distributions of LSP mode and the tip-substrate coupling are also given at the optimal excitation wavelength. These calculation results will be a good reference for the fabrication of metal-coated fiber tips and for the experimental design of the tip-enhanced spectroscopy (TES) system.

Tip-based plasmonic nanofocusing, which delivers light into a nanoscale region and achieves localized electromagnetic (EM) field enhancement beyond the diffraction limit, is highly desired for light-matter interaction-based super-resolution imaging. Here, we present the plasmonic nanofocusing at the apex of a silver (Ag)-coated fiber tip with the internal illumination of a radial vector mode (RVM) generated directly in an optical fiber based on an acoustically-induced fiber grating (AIFG). As illustrated by theoretical calculation, a picture of the nanofocusing plasmonic tip given by analyzing the mode conversion process that the surface plasmon polariton (SPP) mode excited via the radial polarization optical mode can propagate to the apex of the plasmonic tip for nanofocusing because it is not cut off as the tip radius decreases; while the SPP mode which transited from the linear polarization optical mode cannot propagate to the tip apex for nanofocusing because it is cut off as the tip radius decreases. The electric field intensity enhancement factor | E apex 2 | / | E input 2 | $|{\rm{E}}_{{\rm{apex}}}^{\rm{2}}|/|{\rm{E}}_{{\rm{input}}}^{\rm{2}}|$ of a plasmonic tip with a tip radius of 20 nm was calculated to be ~2 × 103. Furthermore, the electric field enhancement characteristic at the tip apex was also experimentally verified by using surface-enhanced Raman spectroscopy (SERS). The Raman scattering intensity was observed to be ~15 times as strong as that with internal illumination using the linear polarization mode (LPM), revealing their significantly different nanofocusing characteristics. A Raman sensitivity of 10−14 m was achieved for the target analyte of malachite green (MG), denoting significant electric field enhancement and effective plasmonic nanofocusing. The energy conversion efficiency of the radial polarization optical mode to the corresponding SPP mode at the tip apex was measured to be ~17%. This light delivery technique can be potentially further exploited in near-field microscopy with improved resolution and conversion efficiency.

Background Thoracic aortic graft infection (TAGI) is a rare and serious complication after surgery for which the treatment is controversial and challenging. Rather than following the traditional surgical strategy of graft replacement and extensive debridement, we have chosen to preserve the graft and cover it by a laparoscopic omental flap. In this article, we describe the clinical manifestation, diagnostic modalities, and treatment of this disease and analyze the role of laparoscopic omental flaps in its treatment. Case presentation We present two cases of thoracic aortic graft infections that had undergone surgical graft replacement for acute Stanford type A dissection. Their clinical manifestation of infection was atypical, with computed tomography suggesting infection of the grafts. Both patients were successfully treated with debridement, laparoscopic omental transposition, and antibiotics. The first case, a 55-year-old male, was found to have an infection at the aortic arch. The second case is a 52-year-old male who was found to have infection at the ascending aorta and arch. Surprisingly, both intraoperative cultures were negative. The infections were brought under control and the patients recovered steadily after surgery. Early follow-up results showed no signs of graft infection. Conclusion These findings suggest that graft replacement for the treatment of TAGI is not always necessary in selected patients. Conservative surgical treatment, including laparoscopic omental transposition, is effective and less invasive for treating TAGI.

We present the plasmon-enhanced nonlinear nanofocusing of a gold (Au) nanoprism array substrate (ANAS) driven via an ultrafast azimuthal vector beam (AVB). Theoretical calculations show that the electric-field intensity of the ANAS vertically excited via the femtosecond AVB is higher than that of LPB excitation. In this experiment, the second-order surface nonlinear optical response of the ANAS is adopted to examine the nonlinear plasmonic nanofocusing of the ANAS, and it was observed that the second harmonic (SH) intensity of the ANAS excited via the femtosecond AVB is ∼3.8 times higher than that of LPB excitation, revealing that the ANAS under AVB excitation has a better nonlinear plasmonic nanofocusing characteristic than that under LPB excitation. Furthermore, the GaSe nanosheets are transferred on the ANAS to examine the nonlinear plasmonic nanofocusing of the ANAS. The SH intensity of the GaSe nanosheets deposited on the ANAS via the femtosecond AVB excitation has been enhanced ∼4.7 times than that of LPB excitation, indicating that the ANAS via AVB excitation has better nonlinear plasmonic nanofocusing than that of LPB excitation. This method may be used as a nonlinear nanofocusing light source to increase the light–matter nonlinear interaction.

Tip-enhanced Raman spectroscopy (TERS) is a promising label-free super-resolving imaging technique, and the electric field gradient of nanofocusing plays a role in TERS performance. In this paper, we theoretically investigated the enhancement and manipulation of the electric field gradient in a bottom-illumination TERS configuration through a tightly focused perfect radially polarized beam (PRPB). Improvement and manipulation in electric field enhancement and field gradient of the gap-plasmon mode between a plasmonic tip and a virtual surface plasmons (SPs) probe are achieved by adjusting the ring radius of the incident PRPB. Our results demonstrate that the method of optimizing the ring radius of PRPB is to make the illumination angle of incident light as close to the surface plasmon resonance (SPR) excitation angle as possible. Under the excitation of optimal parameters, more than 10 folds improvement of field enhancement and 3 times of field gradient of the gap-plasmon mode is realized compared with that of the conventional focused RPB. By this feat, our results indicate that such a method can further enhance the gradient Raman mode in TERS. We envision that the proposed method, to achieve the dynamic manipulation and enhancement of the nanofocusing field and field gradient, can be more broadly used to control light-matter interactions and extend the reach of tip-enhanced spectroscopy.

A humidity sensor is demonstrated using a MoS 2 -coated etched single-mode fiber (ESMF) and applied in human breath monitoring. Because of the interaction between MoS 2 nanosheets and the evanescent field of an ESMF, the light confined within fiber core could be tuned by ambient conditions. The optical frequency conductivity of MoS 2 changes with relative humidity variation, so does the transmission light power of the ESMF. A 14 fold enhancement of light power variation in response to human breaths is achieved compared with a bare ESMF. Fast response and recovery speed (0.066 s response and 2.395 s recovery time) enable this sensor to detect human breath in real time. The results also show the feasibility in monitoring different breath patterns related to the breath frequency and depth.

This study aimed to analyze the early and mid-term outcomes of aortic valve replacement with bovine pericardium in the treatment of aortic valve regurgitation.From January 2015 to March 2018, 36 patients (19 men; mean ± standard deviation [SD] age, 46.70 ± 16.60 years) underwent aortic valve replacement with bovine pericardium. The bovine pericardium was intraoperatively measured and shaped using an Ozaki template, according to the shape and size of the individual patient's aortic valve leaflets. Additional procedures were performed, including ventricular septal defect repair in 5 cases, mitral valve reconstruction in 6 cases, tricuspid valve reconstruction in 6 cases, and coronary artery bypass grafting in 3 cases.There were no perioperative deaths. One elderly patient with postoperative respiratory failure recovered after symptomatic treatment. One patient with frequent ventricular tachycardia after intraoperative cardiac re-jump underwent intra-aortic balloon counterpulsation (IABP), and the IABP device was successfully removed on the second postoperative day. Within the first 6 months of follow-up, there were no death events, no reoperation events, and no additional thromboembolic events. Follow-up echocardiography was performed for 6 months, with average left ventricular ejection fraction of 62.01 ± 3.21%, mean transvalvular pressure gradient of 11.17 ± 4.90 mmHg, and mean aortic valve velocity of 1.60 ± 0.58 m/s. Compared with the preoperative transthoracic echocardiography findings, the results at the six-month follow-up were statistically significant (P0.05). Mild aortic valve regurgitation occurred in 2 patients (5.56%), whereas other patients had no or only minimal aortic valve regurgitation (n = 34, 94.44%). Moderate aortic valve regurgitation occurred in one patient at 9 months after the initial operation. This was found to be due to infective endocarditis, and a biological valve was finally implanted.Aortic valve replacement with bovine pericardium in the treatment of aortic valve regurgitation is feasible, and good early and mid-term results are achieved. Long-term results need to be followed up in the future.

In this paper, we present a convenient and economical method to fabricate a silver (Ag)-film semi-coated polystyrene (PS) nanosphere array substrate for surface-enhanced Raman spectroscopy (SERS). The SERS substrate was fabricated using the modified self-assembled method combined with the vacuum thermal evaporation method. By changing the thickness of the Ag film, the surface morphology of the Ag film coated on the PS nanospheres can be adjusted to obtain the optimized localized surface plasmonic resonance (LSPR) effect. The 3D-finite-difference time-domain simulation results show that the SERS substrate with an Ag film thickness of 10 nm has tens of times the electric field intensity enhancement. The Raman examination results show that the SERS substrate has excellent reliability and sensitivity using rhodamine-6G (R6G) and rhodamine-B (RB) as target analytes, and the Raman sensitivity can reach 10&minus, 10 M. Meanwhile, the SERS substrate has excellent uniformity based on the Raman mapping result. The Raman enhancement factor of the SERS substrate was estimated to be 5.1 &times, 106. This kind of fabrication method for the SERS substrate may be used in some applications of Raman examination.

we present a detailed analysis on nanofocusing and mode evolution process of grating-coupled surface plasmon polaritons on metallic tip with external illumination and metal-coated fiber tip with internal radial vector mode illumination.

Plasmonic tips i.e. silver-film coated fiber tip and silver-nanoparticles coated fiber tip are presented to have the ability of significantly enhancing Raman intensity under the internal illumination of cylindrical vector beams i.e. radial vector beam and azimuthal vector beam respectively. In the case of radial vector beam illumination, the Raman intensity of malachite green is 15 times as strong as that illuminated via the linear polarization beam. In the case of azimuthal vector beam illumination, the magnification of Raman intensity can reach ~8.

We present the generation and nonlinear frequency conversion of nanosecond cylindrical vector beams (CVBs) in two-mode fiber (TMF). Based on the polarized dependence vector mode coupling characteristic and the precise wavelength tunability of an acoustically-induced fiber grating (AIFG), the nanosecond cylindrical vector beams (CVBs, 1064 nm, 10 ns) is directly generated in a TMF with convenient switching characteristics between the radial and azimuthal vector beams. Furthermore, the stimulated Raman scattering (SRS) is produced based on the transmission of the nanosecond CVBs in the 100-meters long TMF, and the spatial intensity and polarization distributions characteristics the 1st-order Stokes shifted component is consistent with the nanosecond CVBs pump pulse. This work provides a method for achieving wavelength conversion of the CVBs in optical fiber.

Background: Conflicting data have been reported related to the impact of atrial fibrillation (AF) on outcomes after transcatheter mitral valve repair with MitraClip (MC) implantation. In this study, we assessed the prognosis of MC-treated patients according to the presence of pre-existing AF. Methods: Randomized and observational studies reporting outcomes of pre-existing AF or sinus rhythm in patients undergoing MC treatment were identified with an electronic search. Outcomes of interest were short-and long-term mortality, stroke, bleeding, rehospitalization, myocardial infarction (MI), cardiogenic shock, acute procedure success, the hospital stay, and the number of Clips implanted. Results: Eight studies (8466 individuals) were eligible. Compared to sinus rhythm, long-term mortality, the risk of bleeding, rehospitalization, and longer hospital stay were significantly higher in AF groups, whereas similar correlations were found in the analysis of other outcomes. Conclusion: AF may be related with worse outcomes in patients undergoing MC implantation, including long-term mortality, major bleeding, and rehospitalization. AF should be taken into account when referring a patient for MC treatment.

A plasmon-induced hot-electron photodetector based on silicon nanopillar array is developed. The nanostructure is fabricated by reactive ion etching with a monolayer of self-assembled polystyrene nanosphere in hexagonal close-packed lattice as the mask. Light absorption and hot-electron generation are mainly enhanced by the surface plasmon polaritons formed at the surface of the gold film on the nanopillar sidewalls. The photoresponse spans two telecom wavebands, viz. the range of 1250-1600 nm, and has a value of 2.5 mA W-1 at 1310 nm. The proposed silicon nanopillar-based hot-electron infrared detector has great potentials for device integration in silicon photonics relying on the economic large-area fabrication process.

Au-nanoparticles (Au-NPs) substrates for surface-enhanced Raman spectroscopy (SERS) are fabricated by scanning an Au-film using femtosecond pulse. The Au-NPs SERS substrates exhibit high activity and excellent reproducibility.

We present the second-order surface optical nonlinear response of a plasmonic tip under axial excitation of ultrafast vector beams. Theoretical calculations show that the tip has an optimized nanofocusing characteristic under axial excitation of the radial vector beam (RVB), and the electric-field intensity enhancement factor is higher than that of linear polarization beam (LPB) and azimuthal vector beam (AVB) excitations. In the experiment, the second harmonic spectra are clearly measured under three excitation beams. The intensity of the second harmonic obtained via RVB excitation is one order of magnitude higher than that of LPB and AVB excitations.

We present a detailed analysis on mode evolution of grating-coupled surface plasmonic polaritons (SPPs) on a conical metal tip based on the guided-wave theory. The eigenvalue equations for SPPs modes are discussed, revealing that cylindrical metal waveguides only support TM01 and HEm1 surface modes. During propagation on the metal tip, the grating-coupled SPPs are converted to HE31, HE21, HE11 and TM01 successively, and these modes are sequentially cut off except TM01. The TM01 mode further propagates with drastically increasing effective mode index and is converted to localized surface plasmons (LSPs) at the tip apex, which is responsible for plasmonic nanofocusing. The gap-mode plasmons can be excited with the focusing TM01 mode by approaching a metal substrate to the tip apex, resulting in further enhanced electric field and reduced size of the plasmonic focus.

Surface-enhanced Raman spectroscopy (SERS) with high-sensitivity performance is a very necessary detection technology. Here, we present a method for increasing the performance of SERS based on silver triangular nanoprism arrays (ATNAs) vertically excited via a focused azimuthal vector beam (AVB). The ATNA substrates with different structural parameters are prepared based on the traditional self-assembled and modified film lift-off technique. Based on a theoretical model established adopting the structural parameters of the ATNA substrates, theoretical simulation results show that AVB excitation can achieve greater electric-field enhancement than linearly polarized beam (LPB) excitation. Experimental result indicates that SERS sensitivity obtained via AVB excitation is 10−13 M (1 M = 1 mol/L) using rhodamine 6G (R6G) as the target analyte, which is 2 orders of magnitude lower than that of LPB excitation (10−11 M). Meanwhile, the uniformity and reproducibility of the ATNA substrates are examined using Raman mapping and batch-to-batch measurement, respectively, and the Raman enhancement factor is calculated to be ∼3.3×107. This method of vector light field excitation may be used to improve the SERS performance of the substrates in fields of ultra-sensitive Raman detection.

We present the plasmon-enhanced linear and second-order surface nonlinear optical response of silver nanoparticles (Ag NPs) fabricated using a femtosecond pulse. Theoretical analysis indicates Ag NPs with a diameter of ∼100 nm have excellent linear response within the visible band, and the electric field intensity enhancement factor reaches ∼105 under excitation of continuous light of 632.8 nm. Meanwhile, the simulation result of second-order surface nonlinear optical response shows that the second harmonic conversion efficiency of the Ag NPs dimer is two orders of magnitude higher than that of a single Ag NP, under excitation of a femtosecond pulse. In experiment, the linear response of Ag NPs is examined using surface-enhanced Raman spectroscopy (SERS) with a Raman enhancement factor of ∼1.7 × 1010, revealing the excellent linear optical response of Ag NPs. Moreover, the spectra of the second harmonic can be measured clearly under conditions of an average pump power of 40 μW, revealing the excellent second-order surface nonlinear optical response of Ag NPs.

We present a method to achieve the dynamic manipulation of optical chirality for a gammadion nanostructure. The gammadion nanostructure is illuminated by two counter-propagating linearly polarized lights (LPLs) with orthogonal polarization directions. By adjusting the phase difference between the two LPLs, the optical chirality enhancement can be adjusted periodically as a function of the phase difference and the optical chirality manipulation range lies between those obtained by single left- and right-handed circularly polarized light excitation. This work provides a convenient and feasible method to achieve the dynamic manipulation of optical chirality for chiral plasmonic nanostructures.

The synergy of a plasmonic tip and fiber-based structure light field excitation can provide a powerful tool for Raman examination. Here, we present a method of Raman spectrum enhancement with an Ag-nanoparticles (Ag-NPs)-coated fiber probe internally excited via an azimuthal vector beam (AVB), which is directly generated in a few-mode fiber by using an acoustically induced fiber grating. Theoretical analysis shows that gap mode can be effectively generated on the surface of the Ag-NPs-coated fiber probe excited via an AVB. The experimental result shows that the intensity of Raman signal obtained with analyte molecules of malachite green by exciting the Ag-NPs-coated fiber probe via an AVB is approximately eight times as strong as that via the linear polarization beam (LPB), and the activity of the AVB-excited fiber probe can reach 10−11 mol/L, which cannot be achieved by LPB excitation. Moreover, the time stability and reliability are also examined, respectively.

Plasmon induced hot electrons have attracted a great deal of interest as a novel route for photodetection and light-energy harvesting. Herein, we report a hot electron photodetector in which a large array of nanocones deposited sequentially with aluminum, titanium dioxide, and gold films can be integrated functionally with nanophotonics and microelectronics. The device exhibits a strong photoelectric response at around 620 nm with a responsivity of 180 μA/W under short-circuit conditions with a significant increase under 1 V reverse bias to 360 μA/W. The increase in responsivity and a red shift in the peak value with increasing bias voltage indicate that the bias causes an increase in the hot electron tunneling effect. Our approach will be advantageous for the implementation of the proposed architecture on a vast variety of integrated optoelectronic devices.

Au-nanoparticle (Au-NP) substrates for surface-enhanced Raman spectroscopy (SERS) were fabricated by grid-like scanning a Au-film using a femtosecond pulse. The Au-NPs were directly deposited on the Au-film surface due to the scanning process. The experimentally obtained Au-NPs presented local surface plasmon resonance effect in the visible spectral range, as verified by finite difference time domain simulations and measured reflection spectrum. The SERS experiment using the Au-NP substrates exhibited high activity and excellent substrate reproducibility and stability, and a clearly present Raman spectra of target analytes, e.g. Rhodamine-6G, Rhodamine-B and Malachite green, with concentrations down to 10-9 M. This work presents an effective approach to producing Au-NP SERS substrates with advantages in activity, reproducibility and stability, which could be used in a wide variety of practical applications for trace amount detection.