Papers by Keyword: Surface Plasmon

Abstract: As a new generation of photovoltaic devices, organic polymer solar cell (Organic Solar Cell, OSC) have attracted wide attention of researchers in recent years because of their unique advantages such as simple process, low energy consumption, low cost and large area preparation. However, the development of OSC has encountered bottlenecks: the low carrier mobility of photovoltaic materials forces the thickness of the active layer of OSC to be reduced as much as possible to meet the requirements of effective collection of photogenerated carriers, while the thinner absorption layer will lead to serious optical absorption loss and device performance degradation. Therefore, how to enhance the optical absorptivity of OSC on the premise of effective carrier collection has become a research hot-spot. Based on this characteristic, with the help of finite element method, the structure model of OSC with multi-tip metal nanoparticles is established, and the effects of metal nanospheres and star particles on OSC light absorption factors are studied systematically. Firstly, the effects of introducing metal nanoparticles into different functional layers of OSC (active layer and buffer layer) are compared and analyzed to determine the introduction location of metal nanoparticles in OSC. Secondly, the localized resonance enhancement rules of spherical and cubic metal nanoparticles in the functional layer are discussed. Combined with the theoretical model, the optimal design method of metal nanoparticles structure parameters (size and period) is established. The results show that the absorption enhancement of metal nanoparticles in the active layer of OSC is higher than that in the buffer layer. On the one hand, it can stimulate more electron hole pair separation, improve the separation rate of electron hole pair, on the other hand, it can also make the separated electron hole to obtain more energy, recombination becomes relatively difficult, and the arrival rate of the battery electrode is improved.

Abstract: New approaches to enhance properties of silicon based quantum dot heterostructures for optical device application were developed. That is strain driven heteroepitaxy, small-sized quantum dots, elemental compositions of the heterointerface, virtual substrate, plasmonic effects, and the quantum dot charging occupation with holes in epitaxially grown Ge quantum dots (QDs) on Si (100). Experiments have shown extraordinary optical properties of Ge/Si QDs heterostructures and mid-infrared quantum dot photodetectors performance.

Abstract: We report on the green synthesis of silver nanoparticles utilizing the P.purpureum leaf extract. Controlling the surface plasmon absorption of silver nanoparticles was achieved by regulating the amount of extract concentration and the molarity of silver nitrate solution. The surface plasmon absorption peak is found at around 430nm. The surface plasmon absorption peak have shifted to lower wavelength as the amount of extract is increased, while plasmon absorption peak shifts on a higher wavelength as the concentration of silver nitrate is increased before it stabilized at 430nm. This can be explained in terms of the available nucleation sites promoted by the plant extract as well as the available silver ions present in silver nitrate solution.

Abstract: We have studied the emission of ortho-positronium from alkali-metal coated polycrystalline tungsten surfaces. The positronium time-of-flight spectra show that the yield of the 5 eV positronium component increases by alkali-metal coating. In addition, a low energy positronium component appears by Cs or K coating. We suggest that this component is due to positron energy loss by inter-band transition or surface plasmon excitation.

Abstract: Phosphor materials have fascinating applications in the field of photovoltaic and biosensors but low quantum yield is a major hurdle in their applications. In this paper, the influence of surface plasmon on the photoluminescence is investigated with surface modified YAG:Ce³⁺-Yb³⁺ coupled with spherical gold nanoparticles. The YAG:Ce³⁺-Yb³⁺ photoluminescence band ratio Yb/Ce rise from 0.25 to 0.32 with the plasmon effects. For the photoluminescence, the decay time of Ce reduces from 31.9 ns to 29.9 ns while for Yb from 54.2 ms to 52.0 ms respectively. Further, the plasmon absorption peak is also observed in the spectra of YAG:Ce³⁺-Yb³⁺/Au nanoparticles system. The results indicate that the field inside the phosphors has been modulated with surface plasmon of gold nanoparticles.

Abstract: We demonstrate a three-dimensional nanostructure design by combining graphene and conventional plasmonic nanostructures, to achieve the high absorbance in the visible region. Furthermore, the peak position and bandwidth of graphene absorption spectra are tunable in a wide wavelength range through a specific structural configuration. Comparing the results of two structures which is based on different materials, Gold and Silver. The structure made of Silver present a better performance. These results imply that graphene in combination with plasmonic perfect absorbers have a promising potential for developing advanced nanophotonic devices.

Abstract: Modifying the optical characteristics of rare earth (RE) doped inorganic glasses by stimulating surface plasmon resonance (SPR) via controlled growth of metal nanoparticles (NPs) is an outstanding quest in glass plasmonics. Glasses with composition 70TeO₂-20ZnO-10Na₂O-(x)Er₂O₃-(y)Au (x = 0.0 and 1.0 mol%; y = 0.0 and 0.6 mol% both in excess) are synthesized using melt-quenching technique and characterized. Influences of heat treatment temperature on the growth of Au NPs and their subsequent impacts on Raman spectral features modifications are inspected. The amorphous nature of glass is confirmed by using XRD. TEM reveal the non-spherical Au NPs with average diameter vary from 7.4 to 10.3 nm. Surface plasmon band is evidenced around 627 - 632 nm. Raman spectra demonstrate the presence of Er-O and Zn-O bond, anti-symmetric vibrations of Te-O-Te bonds and stretching modes of non-bonded oxygen exists in TeO₃ and TeO₃₊₁ unit. The amplifications in Raman signals by a factor of 1.39, 1.40, 0.88 and 1.29 and 1.25 corresponding to the peak centered at 262, 382, 536, 670 and 725 cm^-1 are attributed to the contribution of a surface plasmon (SP) generating a strong, localized and secondary field. The excellent features of the results suggest that our systematic method of controlled NPs growth may constitute a basis for improving the spectral features of tellurite glasses useful for the development of efficient and economic up-converted lasers.

Abstract: Quasiperiodic microstructures are formed on the surfaces of metals under irradiation with high-power femtosecond laser pulses. Interpretation of microstructures as a result of interference of the incident plane wave and surface waves leads to the logical conclusion about the relationship of dislocations in the interference fringes with optical vortices in surface wave. Other peculiarities observed in these structures contain different periods and nanogranular fine structure. It is demonstrated that such laser-induced structures can find applications for surface plasmon excitation and surface enhanced Raman scattering.

Abstract: This presentation provides a panoramic overview of the recent progress in nanoglass plasmonics, challenges, excitement, applied interests and the future promises. A glimpse of our gamut research activities with some significant results is highlighted and facilely analyzed. The term 'nanoglass' refers to the science and technology dealing with the manipulation of the physical properties of rare earth doped inorganic glasses by embedding metallic nanoparticles (NPs) or nanoclusters. On the other hand, the word 'plasmonics' refer to the coherent coupling of photons to free electron oscillations (called plasmon) at the interface between a conductor and a dielectric. Nanoglass plasmonis being an emerging concept in advanced optical material of nanophotonics has given photonics the ability to exploit the optical response at nanoscale and opened up a new avenue in metal-based glass optics. There is a vast array of nanoglass plasmonic concepts yet to be explored, with applications spanning solar cells, (bio) sensing, communications, lasers, solid-state lighting, waveguides, imaging, optical data transfer, display and even bio-medicine. Localized surface plasmon resonance (LSPR) can enhance the optical response of nanoglass by orders of magnitude as observed. The luminescence enhancement and surface enhanced Raman scattering (SERS) are new paradigm of research. A thumbnail sketch of the fundamental aspects of SPR, LSPR, SERS and photonic applications of various rare earth doped/co-doped binary glasses containing metallic NPs are presented. The recent development in nanoglass in the context of Malaysia at the outset of international scenario is projected.

Abstract: A hybrid plasmonic waveguide system consisting of a high-permittivity cylinder waveguide embedded in a low-permittivity dielectric deposited on a metal substrate is comprehensive investigated. With the strong coupling between dielectric cylindrical waveguide mode and the long-range surface plasmon polaritons (LRSPP) mode of a thin metal film, the basic waveguiding properties, including the effective mode area, the propagation length, the mode character, and the figure of merit (FoM) can be achieved. Our results may provide valuable references for waveguiding metal -supported dielectric nanowires for practical applications. An investigation of the effect of structural perturbations indicates that the disturbance of the dielectric nanowires of our proposed waveguide with different surrounding dielectric layer would have a great influence on the experiment results.