Archives June 2023

News on Photonic Crystals

The Journal of Physics: Conference Series published a paper entitled as “Photonic Crystal Design for Bloch Surface Wave Sensing“

Abstract. Bloch Surface Waves (BSW) consist of electromagnetic modes generated at the interface between a photonic crystal and an isotropic dielectric. This type of surface mode displays sharp resonances and high sensitivity to external refractive index variations, and thus appears to be an ideal candidate for usage in optical sensors. Nevertheless, design and optimization of photonic crystals is not a trivial task and constitutes an ongoing field of research. The sensitivity of BSW in both refractometric and adsorption sensing is calculated analytically using first-order perturbation theory for TE modes, allowing the understanding of how several physical parameters of the photonic crystal influence the sensitivity. Preliminary experimental results are presented, which aim to use the analytical calculations to allow for both refractometric and adsorption sensing in a single photonic crystal structure.

Congratulation for our new Paper in Journal of Optik

Glucose sensor based on ellipsometry and circular dichroism in achiral plasmonic structure

Y. Mazhdi, S. M. Hamidi, V. I. Belotelov, A. I. Chernov, R. A. Ejbarah, F. Sohrabi

Various efforts have been made to detect minimum value of glucose in any medium like water or body buffer solutions with high-sensitivity, accurate, and low-cost sensors in order to ameliorate health condition. Therefore, the present study, we have investigated reliability of two-dimensional plasmonic structure by circular dichroism (CD) and ellipsometry tools for detecting different concentrations of glucose. Phase difference between p- and s-polarized light was acquired using ellipsometry technique under the condition of plasmonic-enhanced near-field chirality for the proposed achiral plasmonic 2D grating. Our results confirmed a dependency of the CD signal on glucose concentrations and also a significant sensitivity based on the phase difference between each polarization in ellipsometry parameters with the help of an achiral plasmonic structure.

Congratulations for Our new paper in journal of Magnetism and Magnetic Materials

Comparative Study of Femtosecond Laser-Induced Ultrafast Magnetization Dynamics in Soft Ferromagnetic Ultra-thin alloy

S. M. Hosseini, F. Jahangiri, R. Jalilian, S. M. Hamidi

The typical demagnetization mechanism is applicable in magneto-optic recording systems on a nanoseconds timescale. Interest in this area has expanded rapidly since understanding the physics of ultrafast magnetization processes by experiment are an acutely challenging task. As a result, in order to explain the quenching of magnetization by laser heating in ferromagnetic alloys such as permalloy, we executed a new theoretical study on permalloy, as well as Ni and Fe ultra-thin films with thickness varying from 1 nm to 5 nm. In particular, we demonstrate that the magnetization decays in a timescale of about 0.1 picoseconds by the microscopic three-temperature model. Our free electron model-based theoretical model represents that electron-phonon coupling coefficient and demagnetization time in the thin-films are strongly sensitive to film thickness, pulse duration and laser fluence, respectively. In particular, we show that the rapid demagnetization (100 fs) is due to electron-magnon excitation. This feature improves data processing speed in communication systems and the recording industry.