Search

With increasing x in core/shell Cd1−xZnxS/ZnS QDs, the contribution of short-lived band-edge excitonic to the PL decay increases and the trapping state at the core/shell interface can trap more holes that are excited by multi-exciton Auger process.

The nonlinear absorption of 40 nm Ag nanoparticles (Ag NPs) was investigated using open aperture (OA) Z-scan technique at 532 nm. Experiments show that the nonlinear absorption behavior of Ag NPs is intensity dependent. Specifically, under low laser energy the Ag NPs shows saturable absorption (SA). At medium laser energy, the transformation of nonlinear absorption from SA to reverse saturable absorption (RSA) happens. While under stronger laser energy, double transformation (SA→RSA→SA) of nonlinear absorption occurs. The experimental results were analyzed theoretically using a model based on single-photon absorption and two-photon absorption saturation.

We designed an infrared ultra-broadband metal–insulator–metal (MIM)-based absorber which is composed of a top layer with four different chromium (Cr) nano-rings, an intermediate media of aluminum trioxide (Al2O3), and a bottom layer of tungsten (W). By using the finite-difference time-domain (FDTD), the absorption performance of the absorber was studied theoretically. The results indicate that the average absorption of the absorber can reach 94.84% in the wavelength range of 800–3000 nm. The analysis of the electric and magnetic field indicates that the ultra-broadband absorption rate results from the effect of local surface plasmon resonance (LSPR). After that, the effect of structural parameters, metal and dielectric materials on the absorptivity of the absorber was also discussed. Finally, the effect of incidence angle on absorption was investigated. It was found that it is not sensitive to incidence angle; even when incidence angle is 30°, average absorptivity can reach 90%. The absorber is easy to manufacture and simple in structure, and can be applied in infrared detection and optical imaging.

A high absorption broadband absorber based on MXene and tungsten nanospheres in visible and near-infrared bands is proposed. The absorber has a maximum absorption of 100% and an average absorption of 95% in the wavelength range of 400-2500 nm. The theoretical mechanism and parameter adjustability of the absorber are analyzed by FDTD solutions. The results show that the structural parameters can effectively adjust the absorption performance. The good absorption performance is due to the action of the local surface plasmon resonance coupling with the gap surface plasmon resonance and Fabry-Perot resonance. The simulation results show that the absorber is insensitive to the polarization and oblique incidence angle of incident light, and that high absorption and broadband can be maintained when the oblique incidence angle is up to 60°.

In this paper, we propose a dual-channel mid-infrared toroidal metasurface that consists of split equilateral triangular rings. The electromagnetic responses are analyzed by the finite-difference-time-domain (FDTD) method and temporal coupled-mode theory (TCMT). The results show that one channel of the metasurface is insensitive to the polarization angle of the incident light and temperature, while the other channel is sensitive. The reflectance and resonance wavelength can be manipulated by the polarization angle and temperature independently. Based on such a mechanism, we propose metasurfaces for two-bit programmable imaging and thermal imaging. The metasurfaces are believed to have potential applications in information processing and thermal radiation manipulation.

The electrode materials with a high rate capability and excellent recycling ability are vitally critical for building the supercapacitors, but their synthesis remains a challenge. Herein, we have constructed hollow CoP spheres assembled from 2D porous nanosheet units (HCPS) through the controllable phosphatizing of the pre-designed Co-ethylene glycol (Co-EG) precursor. HCPS have several combined advantages benefiting as the electrode of the supercapacitors, including plentiful accessible ion/electron sites of porous nanosheets, good ability to buffer the volume variation of a hollow structure and enhanced mass/charge transfer due to the high conductivity of the phosphide. The tests show that the optimal HCPS electrode manifests good specific capacitance of 723 F g−1 at 1 A g−1, excellent rate property of 71.21% retention at 30 A g−1. Excitingly, HCPS exhibit super-long cycle stability with 94.3% retention exceeding 50 000 cycles, which can well rival carbon-based electrodes and stands at the forefront of the reported phosphide and oxide-based electrodes. Moreover, an asymmetric supercapacitor (ASC) device equipped with HCPS-positive electrode and negative B, N-doped graphitic carbon (BNGC) electrode presents a high energy density of 38.72 W h kg−1 at a higher power density of 8000 W kg−1 and remarkable stability (96.2% retention after 20 000 cycles), which certifies the promising potential of HCPS for high-efficiency energy storage.

A multifunctional switchable terahertz (THz) absorber based on graphene and vanadium dioxide (VO2) is presented. The properties of the absorber are studied theoretically by the finite-difference time-domain (FDTD) method. The results illustrate that the structure switches between the single-broadband or double-broadband absorption depending on the temperature of VO2. Moreover, the amplitude of the absorptivity can be adjusted by changing the Fermi energy level (EF) of graphene or the conductivity of VO2 separately. Via impedance matching theory, the physical mechanism of the absorber is researched. Furthermore, the effects of incidence angle on absorption have also been studied. It is found that the absorber is insensitive to the polarization of electromagnetic waves.

Purpose This paper aims to clarify the relationship between the performance of the metal nanoparticles and the sensitivity of the fiber surface plasma resonance (SPR) sensor. It proposes modeling the sensing effects of a single-mode fiber SPR sensor with a cone angle structure decorated with metal nanoparticles. This study uses the metal nanoparticles to the realize enhanced sensitivity of refractive index sensing. Design/methodology/approach This paper opted for an exploratory study using a simulation approach of finite-difference time-domain (FDTD). Specifically, the effect of size, the material and the shape of the metal nanoparticle on sensing performance are investigated theoretically. Findings In conclusion, it is evident that the localized SPR (LSPR) effect weakens as the diameter of the gold nanosphere increases, the SPR effect enhances and the SPR sensitivity increases first and then decreases. The metal nanoparticle with the different materials and different shapes also have different LSPR and SPR sensitivity and wavelength length dynamic range. The investigation shows that, by changing parameters, the reflection spectra of the fiber SPR sensor exhibit an obvious transition from LSPR to SPR characteristics, and enhanced sensitivity of the refractive index is realized. Originality/value This paper fulfills an identified need to study how the sensitivity of the fiber SPR sensor can be enhanced by the metal nanoparticle. After the optimization of parameters, the sensitivity of 5,140 nm/RIU is achieved, which provides a new research direction for sensitivity enhancement of fiber SPR sensor.

Nonlinear absorption of multi-layer black phosphorus nanosheets (BPs) were investigated using open aperture Z-scan method with 6 ns nanosecond laser pulses at 532 nm. It was found that, at lower in...

A metal–insulator–metal waveguide structure composed of a hexagonal resonator cavity and a ring with a slit is proposed. By using the finite difference time domain method, the transmission properties of the structure were studied. It was found that three distinct plasmon-induced transparency peaks appear in the visible and near-infrared bands, and the transmissivity of the three peaks is more than 80%. By tuning the structure size, the positions of the peaks can be adjusted. Then we introduced graphene, covering the surface of the cavity. By adjusting the refraction index of the graphene using light, the position of the three transmission peaks can be changed correspondingly. Based on the effect, we designed an all-optical switcher with ultrafast optical response time (about 2 ps) and low light absorption (about 2.3%). The proposed waveguide structure provides a way for the development of visible and near-infrared filters and all-optical switchers.

The process and condition of saturable absorption (SA) and reverse saturable absorption (RSA) of ultrafast nonlinear optics in metal nanoparticles are essential for applications including light generation, amplification, modulation, and switching. Here, we first discover and explore the multiple transformations (SA-RSA-SA) of ultrafast nonlinear absorption behavior of metal nanoparticles in femtosecond pulses. Correspondingly, the energy level model and fitting formula of multiple transformations are established to illustrate the process of optical response. The femtosecond transient absorption spectra provide information about their ultrafast dynamics process and vibrational mode, which further reveals the multiple transformation mechanisms of nonlinear absorption in gold nanobipyramids (Au-NBPs). Furthermore, Au-NBPs exhibit a significantly higher SA modulation depth up to 42% in the femtosecond, which is much higher than the reported values of other nanomaterials. Our results indicate that Au-NBPs can be used as broadband ultrafast Q-switching and mode-locking, and the conversion offers new opportunities for metal nanostructures in applications of optical switching.

In the research of resistant aging, the concentration of Growth differentiation factor-11(GDF11) is an indispensable parameter. So the accurate detection of GDF11 is very important in life science and medical cosmetology. Hereby, we proposed and demonstrated a simple method to detect low concentration GDF11 by using fiber surface plasmon resonance (SPR) sensor decorated with two-dimension (2D) material Ti

Photoactuated liquid crystalline elastomer (LCE) materials are gaining much attention in many application fields, but challenges for the precise modulation of their photoresponses still exist. Researchers have explored various optical parameters, such as polarization, intensity, and wavelength, to obtain differential responses. The development of photoactuated LCE materials with wavelength-selective responsiveness is more versatile and has attracted more interest, but such LCE materials are commonly prepared by incorporating different molecular chromophores or dyes into the LCE matrices. When the surface plasmon resonance (SPR) characteristic of nanometals, which can generate strong photothermal conversion, and the difference of SPR absorption wavelength bands of different nanometals are considered, a strategy of constructing wavelength-selective actuation of LCE materials by using the SPR photothermal effect can be demonstrated, as done herein. The LCE nanocomposites doped by nanogold or nanosilver were fabricated and exhibited good SPR absorption but in different wavelength bands of the visible spectrum range. They had strong actuation under light irradiation with the wavelengths being inside their respective absorption band but could not be effectively actuated by the light beyond their respective absorption band. A smart electronic device, implementing a hierarchical structured LCE nanocomposite doped by nanogold and nanosilver in different domains as the two-switch actuator, was prepared and capable of outputting different signals in response to the different wavelength bands filtered from a light source, which released the actuator from the restriction of light scanning direction or position. Our work provides new insights for the convenient and precise photoactuation of the LCE actuators.

A high absorption broadband absorber based on MXene and tungsten nanospheres in visible and near-infrared bands is proposed. The absorber has a maximum absorption of 100% and an average absorption of 95% in the wavelength range of 400–2500 nm. The theoretical mechanism and parameter adjustability of the absorber are analyzed by FDTD solutions. The results show that the structural parameters can effectively adjust the absorption performance. The good absorption performance is due to the action of the local surface plasmon resonance coupling with the gap surface plasmon resonance and Fabry–Perot resonance. The simulation results show that the absorber is insensitive to the polarization and oblique incidence angle of incident light, and that high absorption and broadband can be maintained when the oblique incidence angle is up to 60°.

In order to obtain optical nonlinear materials with high transparency and low propagation loss in the visible and infrared range, noble metal materials in the off-resonant band have become a hot spot in the optical field in recent years. Therefore, the nonlinear absorption characteristics of platinum nanoparticles (PtNPs) with the surface plasmon resonance (SPR) in the ultraviolet band were investigated with multi-wavelength (500–700 nm) nanosecond Z-scan technology. The measurement results showed that the SPR wavelength of PtNPs was far away from the excitation wavelength, but there were still the saturated absorption (SA) and the reverse saturated absorption (RSA) phenomena, and the size of nonlinear absorption was related to the excitation wavelength and the excitation energy. When the excitation wavelength was constant, with the increase in excitation energy, PtNPs converted from SA to RSA. When the excitation energy was constant, with the excitation wavelength approaching SPR, PtNPs also converted from SA to RSA. The SA and RSA phenomena in the off-resonant region were complementary to the systematic study of the nonlinearity of PtNPs.

We propose and demonstrate a tunable dual-band mid-infrared absorber structure based on the coupling effect of a surface plasmon polariton (SPP) and Tamm phonon-polariton (TPhP). The structure is composed of the distributed Bragg reflector (DBR), air layer, SiC and graphene ribbons. In the air layer, the graphene ribbons are embedded to realize the localized SPP (LSPP), which makes the structure support both the graphene LSPP (GLSPP) and TPhP. The absorption properties of the structure are investigated theoretically and numerically. It is found that strong coupling of the GLSPP and TPhP can be realized by choosing reasonable parameters, which causes a dual-frequency perfect absorption and makes the maximum Rabi splitting of the coupled mode reach 5.76 meV. Furthermore, the mode coupling and absorption intensity can be tuned by adjusting the thickness of the air layer and the Fermi level of the graphene ribbons. This work might provide new possibilities for the development of mid-infrared band sensors, filters and emitters based on the coupling of multiple modes.

Z-scan technology was used to study the nonlinear absorption (NLA) and nonlinear refraction (NLR) of silver nanoparticles (Ag NPs) with various sizes under different laser intensities. The results demonstrate that the NLA and NLR of Ag NPs were size-dependent. Specifically, the 10 nm Ag NPs exhibit saturation absorption (SA) and insignificant NLR. The 20 and 40 nm Ag NPs show the coexistence of SA and reverse saturation absorption (RSA). SA is believed to result from ground-state plasma bleaching, whereas RSA originates from excited state absorption (ESA). The 20 nm and 40 nm Ag NPs shows increasing self-defocusing with the increase of laser intensity. It was observed that the energy relaxation of Ag NPs mainly includes two processes of electron-phonon and phonon-phonon couplings on the order of picoseconds.

A multi-functional broadband absorber based on graphene and strontium titanate (STO) film was designed. Additionally, the frequency, bandwidth, and amplitude of the absorber could be tuned by adjusting temperature and Fermi level of the graphene. By using the finite-difference time-domain (FDTD) method, the numerical calculation result shows that, when keeping the device temperature at 230 K and setting graphene Fermi level to be 1 eV, three absorption peaks at 1.72 THz, 2.08 THz, and 2.59 THz were realized and combined into a broadband absorption from 1.68 to 2.74 THz. As the STO temperature was increased from 230 K to 310 K, the center frequency moved from 2.2 THz to 2.45 THz; correspondingly, the broadband absorption range was widened from 1.06 THz to 1.24 THz. When the temperature was fixed at 230 K and the graphene Fermi level was tuned from 1 eV to 0.7 eV, the absorption bandwidth decreased from 1.06 THz to 0.64 THz. While the Fermi level was tuned continually to be 0.01 eV, only a single absorption peak with an absorption rate of 0.29 existed. The broadband absorption and tuning mechanism of the absorber were analyzed using impedance matching theory. Furthermore, we also studied the effect of incident angle and polarization direction on the properties of the absorber. The multi-functional tunable absorber provides potential applications for the design of more efficient terahertz functional devices in the future.

The light–matter interaction in noble metal nanoparticles is intrinsically determined by the surface plasmon resonance (SPR) and bandgap. To determine the process of electronic transition and the limitation of energy bands on nonlinearity at different excitation wavelengths, we investigate the broadband nanosecond nonlinear absorption of gold nanobipyramids from 532 nm to 850 nm. The experimental results indicate that with the increase of the incident light intensity, gold nanobipyramids have the characteristic of transforming from saturable absorption (SA) to reverse saturable absorption (RSA) at 532 nm to 690 nm, and exhibit a single SA after 690 nm until 850 nm. Based on the wavelength-dependent response, the SA is attributed to the intraband transition of sp-band, whereas sequential two-photon absorption leads to RSA. Unlike other metal nanoparticles, gold nanobipyramids exhibited a significantly higher modulation depth up to 47%. Lastly, building on the excellent SA characteristic, we achieve pulse width compression of nanosecond laser pulses at multi-wavelengths.

OBJECTIVE: To investigate the effect of miR-324-5p on the proliferation of rat glomerular mesangial (HBZY-1) cells and the role of Syk/Ras/c-fos signaling pathway in mediating this effect. METHODS: HBZY-1 cells cultured in vitro were transiently transfected with miR-324-5p mimics or miR-324-5p-mimics-NC followed by treatment with lipopolysaccharide (LPS). MTT assay was used to detect the proliferation activity of HBZY-1 cells, and RT-qPCR was used to detect the expressions of miR-324-5p and the mRNA expressions of Syk, Ras, MEK1/2, ERK1/2 and c-fos mRNA. The protein expressions of p-Syk, Ras, p-MEK1/2, p-ERK1/2 and c-Fos were detected by Western blotting and immunofluorescence assay. RESULTS: MTT assay showed that exposure to LPS significantly enhanced the proliferative activity of HBZY-1 cells. Compared with the cells treated with LPS and LPS + mimics NC, the cells transfected with miR-324-5p mimics prior to LPS exposure exhibited significantly lowered proliferative activity. Transfection with miR-324-5p mimics significantly lowered the mRNA expressions of Syk, Ras, MEK1/2, ERK1/2 and c-fos and the protein expressions of p-Syk, Ras, MEK1/2, ERK1/2 and c-Fos (P < 0.05), and reduced numbers of cells positive for p-Syk, Ras, p-MEK1/2, p-ERK1/2 and c-Fos proteins following LPS exposure. CONCLUSION: miR-324-5p can inhibit the proliferation of rat chronic glomerulonephritis cells induced by LPS by inhibiting Syk/Ras/c-fos signaling pathway and may potentially serve as a diagnostic indicator and a therapeutic target for chronic glomerulonephritis.

The comparative study on nonlinear absorption of WS2 nanosheets was performed by using nanosecond Z-scan measurements at 532 nm and 500 nm. It was found that, WS2 nanosheets exhibit saturable absorption (SA) at low excitation intensities, and the saturable intensity at 500 nm is much stronger than that at 532 nm, which implies that resonance plays main role. With the increase of incident intensity, a switch from SA to reverse saturable absorption (RSA) occurs. Besides, ultrafast dynamics of WS2 nanosheets were investigated by using femtosecond pump-probe technique. Photo-dynamics process was found to contain a double exponential energy relaxation with a fast decay component (14 ps) and a slow one (145 ps).

In this paper, a refractive index sensor based on the control of the fiber core refractive index is proposed. By employing ultraviolet curable adhesive with the different refractive index and hollow capillary fiber, the special fiber with a variable core refractive index is fabricated. Using the special fiber, a novel, to the best of our knowledge, refractive index surface plasmon resonance (SPR) sensor with a controllable detecting range of refractive index is realized. Functional testing of the sensing probes with the core refractive indices of 1.590, 1.516, and 1.454 is performed respectively, indicating that their sensitivities are 1580 nm/RIU, 2220 nm/RIU, and 3467 nm/RIU, respectively, and their detecting ranges of refractive index are 1.385–1.435 RIU, 1.365–1.415 RIU, and 1.335–1.385 RIU, respectively. Furthermore, in order to explore the detection effect of the sensing probe with the higher-core refractive index, we conducted theoretical calculation using the Kretchmann model. The experimental and simulating results indicates that, with the increase of the core refractive index, the magnitude of refractive index that can be detected increases. This study provides a new method for the detection of high refractive index solutions and a new idea for the fabrication of wavelength-division multiplexing distributed SPR sensors.

In order to study the extinction characteristics of gold-silver nanoshuttles, finite difference time domain (FDTD) method was used to simulate the models of gold-silver nanoshuttles with different diameter-length ratios, diameters and cone angles. The simulation results show that with the increase of aspect ratio, the longitudinal absorption peak of the gold-silver nanoshuttles shifts red, while its transverse absorption peak does not change significantly; the longitudinal absorption peak also shifts red with the increase of the length of the central nanorod; and the transverse absorption peak of the gold-silver nanoshuttles shifts blue with the increase of the angle of cone.

We propose an innovative structural design based on a metamaterial absorber in the terahertz band. And verified the absorption curve of the new structure by using FDTD software simulation. The absorption curves of the light source at different incident angles and polarizations were simulated.The simulation results show that the multi-layer covering structure effectively increases the absorption bandwidth of the metamaterial absorber in the terahertz band. And the absorption curve is higher and flatter.

Compared with bulk materials, the corresponding metal nanoparticles have different optical and nonlinear optical effects. The research and analysis show that the properties of nanostructures with different sizes or shapes are different when the materials are the same. For Au nanoparticles, their SPR absorption bands can be tuned throughout the visible spectrum by changing the size and shape of nanoparticles. In this paper, the optical properties of gold nontriangular structures have been studied by finite difference time domain (FDTD) method. The effects of size, thickness and dielectric constant of gold nanometer triangle on its absorption spectrum were discussed. There are three absorption peaks in the cash nontriangular structure. When the thickness is the same (20nm), with the increase of the size of the gold triangular prism structure, the three absorption peaks shift red, the red shift speed increases gradually, and the absorption coefficient increases in turn. The red shift velocity of the main peak absorption peak is stronger than that of the secondary absorption peak. Under the same size structure (100nm), with the increase of gold nanometer triangle thickness, the main absorption peak shifts blue and the absorption coefficient decreases in turn. When the size and thickness are the same, with the increase of dielectric constant, the three absorption peaks shift red, and the absorption coefficient decreases in turn.

Surface plasmon resonance sensor with phase and angular interrogations is proposed in this paper to achieve high sensitivity in a wide dynamic range. The phase interrogation is achieved by Michelson interferometer and the angular interrogation is achieved by rotator. The sensitivity of $7.2\times 10^{-7}$ RIU/0.1° (refractive index unit) and the figure of merit of 316 RIU−1 in a dynamic range from 1 to 1.4 RIU are obtained experimentally. The dynamic range of the sensor covers almost all the gas samples, biological samples, and most of liquid samples, so it can be used as gas sensor, liquid sensor, or biosensor. If the prism with high refractive index (i.e., n >1.9 RIU) is adopted then the dynamic range of the sensor can be higher than 0.6 RIU in principle.

A novel and low-cost fiber birefringence measurement scheme is proposed and studied by a polarimetric fiber ring laser interrogated by the beat frequency technique. For the fiber ring laser, modes splitting occur between two orthogonal polarization modes because of intrinsic fiber birefringence. As a result, two types of beat frequency signals (i.e., longitudinal mode beat frequency and polarization mode beat frequency signals) are generated simultaneously. The principle of measurement of fiber birefringence by the fiber ring laser has been analyzed theoretically in detail. Two alternative expressions for fiber birefringence change are obtained, which is very convenient for users to choose different order longitudinal and polarization mode beat frequency signals. The variation of fiber birefringence caused by applied strain has been calculated in terms of beat frequency shift. To validate the proposed sensing system, the strain-induced fiber birefringence change in commercial Erbium-doped fiber is investigated and obtained by measuring frequency shift of two types of beat frequency signals. The experimental results show that the fiber birefringence experiences a linear decrease when the applied strain is increased. A strain response coefficient of –1.756 × 10–11/μe is obtained. The proposed sensing scheme has obvious advantages of simple structure, low cost, and high sensitivity and it will provide great convenience for measuring fiber birefringence for short-length single mode fiber.

A series of tetra substituted phthalocyanines bearing 2-mercaptobenzimidazole or 2-mercaptobenzothiazole units with different central metals (Zn and In) were synthesized. Their photophysical properties including the parameters of fluorescence and triplet state were studied. The benzothiazole substituted phthalocyanines exhibit stronger third-order nonlinear optical properties (NLO) absorption effects, higher triplet quantum yield (ΦT) and faster intersystem crossing rate compared to the benzimidazole substituted phthalocyanines. With the same central metals, benzothiazole substituted phthalocyanine complexes have the lower fluorescence quantum yield (ΦF), the higher triplet quantum yield (ΦT) and the larger third-order NLO properties as a result of larger conjugated structure and spin-orbit coupling induced by sulphur atoms. The influences of the central metal atoms and the peripheral substituents on the third-order NLO properties are discussed using photophysical parameters.

The optical chain, zigzag and comb shape hollow dark channels were obtained with hollow Gaussian vortex beam modulated by annular aperture filters in 4π focusing configuration. The axial depth of obtained optical chain and hollow dark channels can reach up to 40λ by modulating the parameters of annular aperture filters and beam order in the focal region. And the lateral size of optical chain, zigzag and comb shape hollow dark channels can reach to 0.329λ, 0.672λ and 0.469λ respectively. The obtained optical chain and hollow dark channels can be linearly shifted along the optical axis. The shifted distance of obtained focal optical field was proportional to the phase difference of the two inverse propagated incident beams. The obtained focal optical field had potential application in the fields of multiple particles trapping and multichannel optical data storage.

A bifunctional tunable metamaterial composed of pattern metal structure, graphene, and strontium titanate (STO) film is proposed and studied numerically and theoretically. The dual plasmon-induced transparency (PIT) window is obtained by coupling the bright state cut wire (CW) and two pairs of dark state dual symmetric semiring resonators (DSSRs) with different parameters. Correspondingly, slow light effect can also be realized. When shifting independently, the Fermi level of the graphene strips, the amplitudes of the two PIT transparency windows and slow light effect can be tuned, respectively. In addition, when independently tuning the temperature of the metamaterial, the frequency of the dual PIT windows and slow light effect can be tuned. The physical mechanism of the dual-PIT was analyzed theoretically by using a three-harmonic oscillator model. The results show that the regulation function of the PIT peak results from the change of the oscillation damping at the dark state DSSRs by tuning conductivity of graphene. Our design presents a new structure to realize the bifunctional optical switch and slow light.

In the research of resistant aging, the concentration of Growth differentiation factor-11(GDF11) is an indispensable parameter. So the accurate detection of GDF11 is very important in life science and medical cosmetology. Hereby, we proposed and demonstrated a simple method to detect low concentration GDF11 by using fiber surface plasmon resonance (SPR) sensor decorated with two-dimension (2D) material Ti3C2-MXene and gold nanosphere. The sensitivity of the fiber SPR sensor was increased to be 4804.64nm/RIU. After functionalized with GDF11 antibody, the fiber SPR sensor could specifically recognize GDF11, and the limit of detection (LOD) can reach 0.577pg/L which is 100 times lower than that of single-molecule ELISA method.

The electromagnetically induced transparency (EIT) effects in metamaterials have been widely studied due to their broad application prospects in the field of optical communications. Previous researchers focused mainly on the regulation of a single EIT effect. Here we proposed a structure containing two pairs of asymmetric C-shaped double-split ring resonators (DSRRs) placed on the two sides of cut wire (CW), and we studied the EIT effect of the structure. Furthermore, in order to tune the EIT peak, two graphene strips are placed on the two pairs of DSRRs. Simulation results show that, the EIT peak can be modulated by adjusting the Fermi level of the graphene strips and the modulation depths as high as 83 % and 87 % can be realized. Besides, slow light phenomenon accompanied by the EIT effect in the structure was investigated. Simulation results implied that, double group delays of 4.4 p s and 3.4 p s can be achieved in the design, and the delays can be adjusted by changing the graphene Fermi level. The physical mechanism of the tunable metamaterial was analyzed in terms of the three-oscillator model.

The localized surface plasmon resonance (LSPR) of Ag nanosphere array and KTN@Ag (nano KTa0.65Nb0.35O3 with Ag at it’s the surface) core-shell nanoarray are elaborately analyzed based on finite-difference time-domain (FDTD). The effects of particle spacing, core size and shell size on LSPR for the KTN@Ag core-shell nanoarray structure are systematically investigated. The results indicate that the core size and shell size for the KTN@Ag core-shell nanoarray structure have a great influence on LSPR. With the increase of the Ag shell radius, the resonance absorption appears blue-shift from 878 nm to 660 nm. With the increase of KTN core radius, the resonance absorption peak exhibits significantly red-shift from 538 nm to 867 nm. Thus, the designed KTN@Ag core-shell nanoarray structure can realize the effective regulation of LSPR in a wider range, which is obviously better than the Ag nanosphere array. The controllable LSPR wavelength enables the KTN@Ag core-shell nanoarray to serve as plasmonic nanosensors. This study provides a theoretical basis for the future application of KTN@Ag core-shell nanoarray structure in optical and optoelectronic devices.