Magnetoplasmonics Lab
News On Biosensors

The Journal of  IEEE Sensors published a paper entitled as “Ultra-Sensitive Refractive Index Sensors Based on Bloch Surface Waves With Transition Metal Dichalcogenides”

Abstract—Bloch surface wave (BSW) sensors are considered to be a great candidate to replace the conventional surface plasmon resonance (SPR) sensors. In this paper, a high performance refractive index sensor based on BSW resonance in the truncated one-dimensional photonic crystal (1DPC) has been theoretically confirmed using transition metal dichalcogenides (TMDCs). The impact of four different two-dimensional TMDCs nanosheets on the sensors are studied, with which the state of art sensitivity of wavelength-interrogation has been achieved. Specifically, with MoSe2, WSe2, MoS2 , and WS2 nanosheets, the measured figure of merit (FOM) are 732.1/RIU, 733.0/RIU, 730.5/RIU, and 700.7/RIU, respectively. To our knowledge, this is the best performance achieved so far compared to the existing BSW and SPR sensors. Besides, the impact of the 1DPC period and the number of TMDCs layers were discussed in detail. In addition, at the interface of TiO2 and TMDCs, it is found that the electric intensity is enhanced by nearly 7 times compared to the initial intensity, which also results in an increased evanescent depth in the sensing medium. The high sensitivity sensors proposed in this paper can be applied in the field of biological and chemical sensing.

Congratulations for Our New Paper in Journal of ACS Omega

Metastructure Engineering with Ruddlesden−Popper 2D Perovskites: Stability, Flexibility, and Quality Factor Trade-Offs

Seyedeh Bita Saadatmand, Samad Shokouhi, Vahid Ahmadi, and Seyedeh Mehri Hamidi

ABSTRACT: In this study, we investigate the opto-electro- mechanical properties, thermodynamic stability, and moisture stability of the Ruddlesden−Popper (RP) two-dimensional perovskites of L2PbI4 (L = PEA, FPEA, BA, and BZA) using density functional theory. The goal is to explore their potential application in metastructures. The results show that the stability of FPEA2PbI4 is better than that of PEA2PbI4, BA2PbI4, and BZA2PbI4 due to the replacement of a hydrogen atom with a fluorine atom. On the other hand, BA2PbI4 is more flexible than other materials because it lacks an aromatic ring in its spacer cation, but it is less stable. We introduce a new kind of metastructure composed of an RP perovskite film and conduct an extensive investigation of the quasi-bound states in the continuum (q-BIC) characteristics by near-field analysis and multipole decomposition calculations. The q-BIC resonances in BZA2PBI4 have a greater quality factor due to its larger refractive index in comparison to other materials. Therefore, based on these results, the perovskite materials can be selected for the metastructures from different aspects of stability, flexibility, and refractive index.

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congratulations for Our New Paper

Congratulations for Our New Paper in Journal of Theoretical and Applied Physics (JTAP)

2D plasmonic micro-square arrays based on innovative two-step pattern transfer and plasma treatment for high-efficiency Si solar cells

Neda Roostaei, Seyedeh Mehri Hamidi, K. -W.-A. Chee

Silicon (Si) photovoltaic cells and their production play a pivotal role in advancing energy utilization within the rapidly expanding solar industry, which serves as a critical driver in realizing global sustainability objectives and mitigating environmental repercussions associated with energy production. Here, we introduce a novel two-step pattern transfer technique to successfully imprint a two-dimensional plasmonic micro-square periodic array onto an Si substrate, utilizing Kapton®️ Tape and plasma technology. Remarkably, this represents the first-ever application of flexible and stretchable Kapton®️ polyimide for pattern transfer onto Si. The vacuum plasma treatment plays a pivotal role in significantly enhancing surface adhesion performance, thereby facilitating the efficient pattern transfer process. As a result, the resulting microstructure exhibits exceptional performance as a plasmonic broadband absorber in the visible region, making it a highly promising candidate for enhancing efficiency in Si-based solar cells. To support our experimental findings, the finite-difference time domain method was employed for simulating the fabricated plasmonic structure and determining the electric field distribution. The simulation results unequivocally affirm the robust and intense light trapping capabilities of the microstructure. Moreover, our fabrication technique demonstrates the potential for achieving high-resolution microstructure through an innovative, straightforward, and cost-efficient approach.

News on smart contact lens

In these days, the Nature Communications published a paper entitled as “Frequency-encoded eye tracking smart contact lens for human–machine interaction

Abstract

Eye tracking techniques enable high-efficient, natural, and effortless human-machine interaction by detecting users’ eye movements and decoding their attention and intentions. Here, a miniature, imperceptible, and biocompatible smart contact lens is proposed for in situ eye tracking and wireless eye-machine interaction. Employing the frequency encoding strategy, the chip-free and battery-free lens successes in detecting eye movement and closure. Using a time-sequential eye tracking algorithm, the lens has a great angular accuracy of <0.5°, which is even less than the vision range of central fovea. Multiple eye-machine interaction applications, such as eye-drawing, Gluttonous Snake game, web interaction, pan-tilt-zoom camera control, and robot vehicle control, are demonstrated on the eye movement model and in vivo rabbit. Furthermore, comprehensive biocompatibility tests are implemented, demonstrating low cytotoxicity and low eye irritation. Thus, the contact lens is expected to enrich approaches of eye tracking techniques and promote the development of human-machine interaction technology.

News on crystal magnetic sensor

A novel Bloch surface wave (BSW)-based one-dimensional photonic crystal magnetic sensor is proposed. Gratingis used to realize the coupling of electromagnetic waves and BSW, and magnetic fluid is placed at the bottom ofthe sensor as the sensing medium. The sensing characteristics of a one-dimensional photonic crystal magneticsensor were analyzed using the rigorous coupled wave analysis (RCWA) method. Based on the azimuthalinterrogation method, the effects of different pole angles, defect layers, and structural parameters on sensitivityand figure of merit (FOM) were investigated. According to the drift of the resonance peak, the azimuthalsensitivity S = 9 ◦/mT, and the maximum detection sensitivity S = 14 ◦/mT were obtained (converted torefractive index sensitivity S = 6536 ◦/RIU and maximum detection sensitivity S = 9333 ◦/RIU). Excitingly, wefound that the introduction of a defective layer can significantly improve the FOM (1925 RIU− 1 to 69,444RIU− 1). The results show that the designed magnetic sensor structure has high sensitivity and a high FOM, whichis an order of magnitude higher than other magnetic sensors. This work provides a guideline for the futuredevelopment of one-dimensional photonic crystals in the field of weak magnetic sensing.

News on Plasmonic Perovskite Solar Cell
Our new paper in Journal of Optik

S.T. Sajjadian, K.-W.-A. Chee, R.A. Ejbarah, S.M. Hamidi, Y. Alissa, S. Sadeghi

Corresponding Author: m_hamidi@sbu.ac.ir

Abstract:

Addressing limited access to clean drinking water demands innovative solutions to energy and environmental crises. Photocatalysis offers promise without eliciting secondary pollution, yet traditional metal oxide semiconductor photocatalysts encounter impediments in solar energy utilization and charge carrier recombination rates. To overcome these limitations, we present for the first time, a novel design, fabrication, and characterization of two-dimensional plasmonic noble metal/perovskite nanostructure hybrids for photocatalysis, combining Au as the plasmonic material with Cu-modified SrTiO3 as the semiconductor, fabricated on elastomeric polydimethylsiloxane substrates. Integrating localized surface plasmon resonance and Schottky junction-related band-bending significantly extends optical absorption into the ultraviolet-visible-infrared bands and enhances the effective carrier lifetimes, ensuring state-of-the-art photocatalytic efficiency. Exceptional photocatalytic performance in a 5-ppm aqueous methylene blue solution can be attained with 72.69-wt. % Cu incorporation in the perovskite oxide, reaching a visible light-mediated photodegradation efficiency of 26% – an astounding 62.5-% efficiency increase compared to previous experiments without Cu modification. This advancement underscores the synergistic potential of noble metals and photocatalytic semiconductors in managing water purification challenges.

winter school of quantum photonic technologies

The first winter school of quantum photonic technologies to present new opportunities of quantum optics technology and design roadmap for young talented researchers

?quantum photonic research and technology center, laser and plasma research institute

Our Group Meeting

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Ms. Sanchooli presented a seminar titled as “Investigating effective parameters in cells used in saturation absorption and fluorescence spectroscopy”