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Tunable and reversible thermo-plasmonic Hot spot imaging for temperature confinement

N. S. Shnan, N. Roostaei, S. M. hamidi

In the present study, a novel tunable two-dimensional thermo-plasmonic grating based on gold nanorods was demonstrated by combining the plasmonic properties of the gold nanostructure and the applied external voltage. In this structure, a thin layer of the gold grating was typically deposited on a patterned poly-dimethyl-siloxane substrate using the nanoimprint lithography method. The surface plasmon resonance of the fabricated plasmonic structure was excited by the surface plasmon imaging system based on a high numerical aperture objective lens and the charged coupled device camera. Based on the results, the number of the plasmonic hot spot due to the thermo-plasmonic effect increased by the external voltage, leading to an increase by this effect. Therefore, this reversible and tunable temperature confinement can be used as the controller of each element including cells in a defined micro-position.

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Surface lattice resonance-based magneto-plasmonic switch in NiFe patterned nano-structure

H. Mbarak, S. M. Hamidi, V. I. Belotelov, A. I. Chernov, E. Mohajerani, Y. Zaatar

In this work, a 2D magneto-plasmonic grating structure combining materials with ferromagnetic and plasmonic properties is demonstrated. NiFe composite ferromagnetic material, as an active medium with tunable physical properties, and Au metal, as a plasmonic excitation layer, were the materials of choice. Here, we have experimentally investigated the active control of the plasmonic characteristics in Au/NiFe bilayer by the action of an external magnetic field, as well as the switching effect of the system. The active plasmonic control, can be achieved by the magnetization switching of the ferromagnetic material, opening a new path in the development of active plasmonic devices. To our best knowledge, this is the first demonstration of such a magneto-optical plasmonic switch based on the coupling of plasmons with magneto-optical active materials, in which the response time was estimated to be in the range of microseconds.

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Membrane activity detection in cultured cells using phase-sensitive plasmonics

Foozieh Sohrabi, Yasaman Jahani, Jose Vicente Sanchez Mut, Ershad Mohammadi,Zahra Barzegar,Xiaokang Li, Liliane Glauser, Johannes Gräff, And Seyedeh Mehri Hamidi

Despite the existence of various neural recording and mapping techniques, there is an open territory for the emergence of novel techniques. The current neural imaging and recording techniques suffer from invasiveness, a time-consuming labeling process, poor spatial/ temporal resolution, and noisy signals. Among others, neuroplasmonics is a label-free and nontoxic recording technique with no issue of photo-bleaching or signal-averaging. We introduced an integrated plasmonic-ellipsometry platform for membrane activity detection with cost-effective and high-quality grating extracted from commercial DVDs. With ellipsometry technique, one can measure both amplitude (intensity) and phase difference of reflected light simultaneously with high signal to noise ratio close to surface plasmon resonances, which leads to the enhancement of sensitivity in plasmonic techniques. We cultured three different types of cells (primary hippocampal neurons, neuroblastoma SH-SY5Y cells, and human embryonic kidney 293 (HEK293) cells) on the grating surface. By introducing KCl solution as a chemical stimulus, we can differentiate the neural activity of distinct cell types and observe the signaling event in a label-free, optical recording platform. This method has potential applications in recording neural signal activity without labeling and stimulation artifacts.

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Toward ultra-sensitive diagnostic chips

An international team, led by Swinburne researchers, has developed an ultra-thin nanostructure gold film—or metasurface—with the potential to revolutionize next-generation bio-sensing chips. The new metasurface could be used to create an extremely sensitive diagnostic chip to detect disease in small amounts of body fluids.
The researchers, co-led by founding director of the Centre for Translational Atomaterials, Professor Baohua Jia and Head of the Nonlinear Physics Centre at the Australian National University (ANU), Professor Yuri Kivshar recently developed the metasurface, which is capable of strong light-matter interaction with higher sensitivity.
The metasurface consists of an array of standing double-pillar meta-molecules that support strong dark mode resonances or electromagnetic configurations that can ‘trap’ light energy and prevent it from escaping. Once the dark modes are excited, the structure ‘squeezes’ light into the tips of the pillars.
“When the metasurface is illuminated by light at some specific oblique angles, dark modes can be excited and they can ‘trap’ all the energy of incident light, leading to the highest field enhancements at the tips of pillars,” says first author of the paper and Swinburne Ph.D. candidate Yao Liang.
“Because the mode is trapped and squeezed, the field becomes so high that an ultrahigh quality factor, the so-called Q-factor used to describe how well the device is able to trap the light in the device, can be achieved,” says co-author ANU Ph.D. candidate Kirill Koshelev. The strong light field enhancement in the infrared molecular fingerprint wavelength region has many applications.

The breakthrough shows great potential for other applications such as ultra-fast thermal imaging and quantum emitters.

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Journal of Advanced Materials publishes a paper entitled as “A Plasmonic Sensor Array with Ultrahigh Figures of Merit and Resonance Linewidths down to 3 nm”

Surface plasmon polaritons (SPPs) are extremely sensitive to the surrounding refractive index and have found important applications in ultrasensitive labelfree sensing. Reducing the linewidth of an SPP mode is an effective way to improve the fgure of merit (FOM) and hence the sensitivity of the plasmonic mode. Many efforts have been devoted to achieving a narrow linewidth by mode coupling, which inevitably results in an asymmetrical lineshape compromising the performance. Instead, the SPP modes are directly narrowed by elaborately engineering periodic plasmonic structures with minimized feature sizes to effectively reduce the radiative losses. A narrow linewidth smaller than 8 nm is achieved over a wide wavelength ranging from 600 to 960 nm and a minimum full width at half maximum of 3 nm at 960 nm. Benefting from the almost perfect Lorentzian lineshape and the extremely narrow linewidth, a record FOM value of 730 is obtained. The sensor is capable of detecting bovine serum albumin with an ultralow concentration of 10-10 m. The sensor has great potential for practical application for its ultrahigh FOM, broad working wavelength, and ease of high-throughput fabrication.

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Strong exciton-plasmon coupling in waveguide based plexcitonic nanostructure
T. Mahinroosta, S. M. Hamidi

A new two-dimensional plexcitonic structure based on coupled-resonator optical waveguides is demonstrated to enhance light-matter interactions in the J-aggregate molecules coupled to the plasmonic resonator. For this purpose, we define four different plexcitonic structures by adjusting the coverage of dye medium over the plasmonic structures and forward or backward illumination directions, which examined by the finite difference time domain method. Our results show that several parameters could be used to sweep plasmon-exciton coupling in the weak, intermediate, and strong coupling regimes such as the type of structures (single or array of nanodisks), the radius of nanodisks, the direction of the incident light and the concentration of JA molecules. From the presented results, there are remarkable values for Rabi splitting by tuning these parameters, and it has achieved that the sample with the coverage of dye in the style of the plasmonic pattern in the backward illumination offers higher strength of the plasmon-exciton coupling, and then Rabi splitting is about 670 meV for the radius set to 90 nm. This amount of splitting in this new kind of plexcitonic structure can open new insight in low cost and efficient hybrid structures.

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Many congratulations to Dr. Khodeary for achieving PHD degree. Wish you many years of achievement of your goal and success.

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Phase-Sensitive Pulse Sensor Using Two-Dimensional Active Plasmonics on Conformal Substrates

Foozieh Sohrabi, Mohsen Kiaei, Tayebeh Mahinroosta and Seyedeh Mehri Hamidi

Real-time monitoring of the vital signals using flexible and portable biosensors plays an important role in future human life. However, there is most often a tradeoff between the improvement of the mechanical properties of these sensing chips and their sensitivity. In this study, we proposed two-dimensional polydimethylsiloxane/Au and silk/Au chips with microhole and microparticle patterns performing in an integrated platform of plasmonic-ellipsometry. Under external sinusoidal signal, we observed the regular dependency of the optical responses and plasmonic resonances on the frequency and not on the current. Using integrated plasmonic-ellipsometry technique and the phenomenon of active plasmonics, PDMS/Au microhole chip has demonstrated that Δ and Ψ parameters became lesser by increasing the frequency and the resonance wavelength underwent the redshift. However, for silk/Au chip with inverse pattern of microparticle bumps, Δ and Ψ had augmentation trend with respect to the frequency and the resonance wavelength shifted to shorter wavelengths. By optical and thermal analysis, we have demonstrated that this study can open new insight in fabricating optically phase and amplitude sensitive biosensors based on conformal substrates with thermo-optical properties that can behave in redshift and blueshift regimes.

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In this days, Journal of Optics Communications publishes a new paper entitled as “High-sensitive optoelectronic SPR biosensor based on Fano resonance in the integrated MIM junction and optical layers”

A. Lotfiani, S. M. Mohseni, and M. Ghanaatshoar

Abstract— Development of the miniaturized surface plasmon resonance (SPR) sensors with high sensitivity is required for biomedical sensing applications. In this regard, elimination of the optical detector and enhancement of sensitivity is an important step towards miniaturization of the traditional Kretschmann SPR sensors. In this study, we propose a compact high-sensitivity SPR biosensor with an electrical response based on Fano resonance in the metal-insulator-metal (MIM) junction integrated with the planar waveguide (PWG). The SPR excitation at the top metal of the MIM junction enhances the photoabsorption and hot electrons generation, which can produce photocurrent. We demonstrate that the coupling between the MIM junction SPR and PWG modes can result in modulation of output photocurrent by variation of analyte refractive index. The response of this sensor was calculated in detail and the results showed that the Fano-like profile appears in the photocurrent curve as well as the reflectivity curve. To evaluate the sensing performance of the proposed structure, the figure of merit (FOM) for the bulk sensitivity is predicated as 3.4×103 RIU-1, which is translated to change in the photocurrent of 33.5 μA by introducing the variation of 0.0001 in the refractive index of the analyte. Our results are highly useful for designing an integrated multi-function detector for future diagnoses and sensing applications.

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Many congratulations to Dr. Saddam alhaddawi for obtaining PHD degree. Wishing for you great success in all steps of your life.



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