Magnetoplasmonics Lab

Archives August 2019

Our new paper in journal of Optik

Congratulations to our new paper”Control of nonlinear refractive index of AuNPs doped with nematic liquid crystal under external electric field” by H. Mbarak, A. K. Kodeary, S. M. Hamidi, E. Mohajarani, Y. Zaatar

In the present work, the nonlinear refractive index of gold nanoparticles (NP) doped with nematic liquid crystal (NLC) is determined using Z-scan technique. The gold NPs were synthesized by laser ablation (Nd: YAG laser at 1064 nm) dispersed in liquid deionized water. This work was especially done using a close aperture placed in front of the detector to show the effect of the nematic liquid crystal (E7) on the nonlinear refractive index of the Au NPs under an external electric field. It’s found experimentally, that the nonlinear refractive index of the gold nanoparticles doped with E7 can be varied by changing both the compositional percentage of gold NPs and NLC molecules. The obtained nonlinear refractive index of the samples showed that nematic liquid crystal (E7) can act as a good material for controlling the third order nonlinear coefficient due to its large nonlinear optical properties.

    Our new paper in journal of Applied physics

    Congratulations to our new paper”Two-Dimensional Plasmonic Biosensing Platform: Cellular Activity Detection under Laser Stimulation” by Sajede Saeidifard, Foozieh Sohrabi, Mohammad Hossein Ghazimoradi, Seyedeh Mehri Hamidi, Shirin Farivar, Mohammad Ali Ansari

    Combing biosensors and nanoscience as a growing technique provides great advantages such as a label-free and real time analysis, high sensitivity, low limit of detection, small size and integration to other systems. That is why plasmonics finds various applications in drug detection, food safety, agriculture, photothermal therapy, etc. In this paper, we have fabricated a two-dimensional plasmonic grating biosensor using soft lithography technique, which has eliminated some disadvantages of conventional plasmonic structures like expensive fabrication cost, inflexibility and lack of mass production. On the other hand, we benefited from infrared neural stimulation for regulating membrane depolarization, which is based on photothermal mechanism and provides a contact-free and high spatial/temporal resolution. Eventually, membrane depolarization of two different cell-types of Herpg Hodode (Hep G2) and Mesenchymal stem cell cultured on two-dimensional plasmonic has been investigated under infrared neural stimulation. After preparing the soft plasmonic crystal, its reflection spectra and respective ellipsometry parameters were analyzed before and after cell culture with/without stimulation (near-infrared immune region ~1450 nm). By comparing the obtained ellipsometry results for HEP G2 and mesenchymal stem cells, it is observed that the behavior of two cell types with respect to IR stimulation is the same besides providing us the possibility of distinguishing the level of membrane depolarization under various stimulating frequency.
    The strength point of this integrated system for membrane depolarization detection has been shown experimentally which can open new avenues toward neuroplasmonic application in the future.

    Our new paper in journal of Optics and Laser technology

    Congratulations to our new paper “Signature of plasmonic nanoparticles in multi-wavelength low power random lasing” by S. F. Haddawi, Hammed R. Humud, S. M. Hamidi 

    A multi-wavelength plasmonic random lasing is attained by core-shell nanoparticles and the mixture of metallic nanoparticles in the host dye medium. The plasmonic nanoparticles, fabricated using laser ablation in liquid, were mixed in the corresponding dye medium and pumped with green nano-second pulsed laser. Due to this optical pumping process of plasmonic nanoparticles, amplification of the fluorescence and the lasing activity took place due to the localized surface plasmon resonance and scattering of each nanoparticle, core-shell and mixture nanoparticles. Our results show efficient coherent random lasing due to the interface between two different metallic nanoparticles in the middle part of the visible spectral region considering its applicability in the design and fabrication of compact and miniaturized random laser sources.

    Our new paper in journal of Magnetism and magnetic materials

    Congratulations to our new paper “Bi:YIG@Au Magneto-Plasmonic Core-Shell Nano-Grating with Robust, High Magneto-Optical Figure of Merit” by Somayeh Sadeghi, Seyedeh Mehri Hamidi

    We numerically examine the role of Fano resonance for enhanced magneto-optical effect in an arrayed magneto-plasmonic core-shell structure composed of Bi:YIG cores as a magneto-optical active medium and Au sells as plasmonic ones. The optical and magneto-optical behavior of the magneto-plasmonic core-shell grating structure sustaining Fano resonance is investigated by means of Lumerical software based on the finite-difference time-domain solver. In the proposed structure, Fano resonance arises from the interplay between the guided mode and the surface plasmon resonance which results in enhanced magneto-optical Faraday effect. In addition, the Fano resonance and correspond enhanced magneto-optical effect can be tuned by changing the array period of the structure. The obtained results can be of interest in miniaturized and advanced magneto-optical devices.