International Journal of

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We report an experimental study on optical and magneto-optical properties of Cesubstituted yttrium iron garnet thin films incorporating gold nanoparticles. Au nanoparticles were formed by heating Au thin film on cubic quartz and garnet substrate in vacuum chamber and a Ce:YIG layer was deposited on them by the aid of Pulsed laser deposition method. A large enhancement of the longitudinal Kerr effect was obtained in sample with Au nanoparticles on quartz substrate and the effect of substrate material on improving optical and magneto-optical response of samples were investigated.

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Recently atomic magnetometers are one of the best tools in biomagnetic measurement such as magnetic field of brain and heart. In this paper, the technology of optically pumped atomic magnetometer based on circularly polarized light absorption pumping is described. We have been investigated a new method for measuring polarization effect in an alkali vapor based on polarized light transmission. In addition several magnetometers’ response factors such as cell temperature, laser’s intensity are introduced and reviewed. Our results show that the difference between absorption of circular and linear light not only depends on polarization, but also in number of polarized atoms.

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We examine the photo-assisted polarization loop in a BiFeO₃ thin film under UV light illumination. BiFeO₃ thin film prepared by pulsed laser deposition method onto the BaTiO₃ thin film and the polarization behavior has been measured under poling voltage. Our results show the engineered polarization due to controllable schottky barrier under inverse poling voltage. This control on schottky barrier height and then polarization of thin film can be opened the new insight in the ferroelectric devices.

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Compared to the long history of plasmonic gratings, there are only a few studies regarding the bandgap in the propagation of plasmonic surface waves. Considering the previous studies on interpretation of plasmonic bandgap formation, we discuss this phenomenon using the effect of both surface plasmon polariton (SPP) and localized surface plasmon (LSP) for our fabricated one-dimensional metallic-polymeric grating. This structure is composed of metallic grating on the surface of PDMS with different concentration of embedded gold nanoparticles. By sweeping the incident angles, we have seen that the SPP, LSP and their coupling cause two gaps in reflection regime which are originated from SPP supported by thin film gold film and LSP supported by gold nanoparticles. The first gap is attributed to the patterned metallic film because it vanishes by increasing the nanoparticles which may destroy the pattern while the second gap can be formed by embedded nanoparticles because it becomes more considerable by raising the incubation time. Therefore, the drowning time of patterned samples (e.g. 24h, 48h, and 72h) in HAuCl4 plays the key role in adjustability of plasmonic bandgap. Notably, the interaction between SPP and LSP can be the origin of the shift in gap center from 300 to 550. To best of over knowledge, this study is the first study on the plasmonic band gap as a function of both SPP and LSP.

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Atomic magnetometers have found widespread applications in precise measurement of the Earth’s magnetic field due to their high sensitivity. In these measurements, various methods have been utilized to compensate the Earth’s magnetic field in an unshielded environment. In this paper, we have proposed a method based on finding the minimum resonance frequency (corresponding to minimum magnetic field) by producing the opposite magnetic field through three pairs of Helmholtz coils. The exact value of the Earth’s magnetic field vector is obtained as 35.132 μT with an accuracy of 2 nT by using this method.

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Silver nanowires are the favorable material in many applications based on their plasmonic double resonance in the visible region. In this paper, thin films of Poly-vinyl-pyrrolidone (PVP) doped with Silver nanowires (Ag NWs) in different concentrations have been prepared. The plasmonic imaging system using a high numerical aperture objective lens excite the Surface Plasmon in these structures. The hot spot results from reflected light intensity of surface plasmon resonance (SPR) proved that increasing of concentration of Silver nanowires yields to get better hot spot in plasmonic imaging systems by choosing the appropriate wavelength. These obtained results accompanying with third order nonlinear investigations show the ability of samples usage in thermoplasmonic applications.

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Two-dimensional nanomaterials have attracted increasing attention for enhancing surface plasmon resonance (SPR) biosensors application. In this work, we use the graphene layer to improve the sensitivity of the SPR biosensors based on the conventional Kretschmann configuration. We employ Tungsten disulfide (WS₂) and Molybdenum disulfide (MoS₂) Two-dimensional materials as an interlayer to enhance the sensitivity of Au/Graphene biosensor in angle interrogation method. The transfer matrix method (TMM) is used to analyze the characteristics of the device. Results show that using WS₂ in Au/Graphene structure increases sensitivity by about 12.64%, which is higher than MoS₂. Combining graphene based SPR and ellipsometry as a highly sensitive, label-free, real-time, and versatile method can be used to measure a very small concentration of biomolecules, which leads to 170-fold enhancement compared to angle interrogation method and improves the detection accuracy and quality factor.

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Recently, color production by using plasmonic structures has widely been studied. In this research, a flat and flexible two-dimensional Kapton-copper plasmonic crystal with very low thickness has been fabricated in a new and optimal way. Color production is performed using our proposed plasmonic structure and different colors are achieved by changing the incidence angle of light. Also, the plasmonic resonance response of the fabricated structure has been recorded at the incidence angle of 58 degrees. Advantages of our proposed structure are low cost, easy fabrication, and very small dimensions, and thus this research can be useful due to the increasing needs for the integration and miniaturizing of optical devices in modern nanophotonic systems.

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ta charset="UTF-8" >Color vision deficiency (CVD) is a disorder in which patients cannot distinguish specific colors. In the last few decades, the researchers have attempted to find a solution to cure this deficiency, despite valuable attempts by scientists, a promising and effective remedy has not been attained yet. As curing of CVD with the tinted or dyed glasses and lenses in colorblind patients is not satisfying, in this work, we have studied a novel and simple method using plasmonic gold nanoparticles in the contact lenses to improve CVD based on surface plasmon resonance of gold nanoparticles in the visible spectral range. In this technique, the dispersion of gold particles into the contact lens and transforming them to plasmonic gold nanoparticles provides a color filter that can be applied in the correction of the red-green type of colorblindness.The modified lens blocks a narrow band centered at 560nm, the wavelength that vision spectra of CVD patients overlap at those ones. 

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Optical diffusers are optical elements for smoothing the spatial distribution of light through irregular light scattering. Recently, the fabrication and engineering of optical diffusers has attracted many attentions. In this research, an optical diffuser was fabricated using silicon carbide ceramic powder and by placing the diffuser in the optical path of the experimental setup of optical transmission microscope, the spatial intensity distribution was investigated. The uniform and symmetric spatial distribution was achieved after placing the diffuser in the optical path, and the intensity distribution diagrams were obtained corresponding to the Gaussian distribution. Finally, two-dimensional samples based on polydimethylsiloxane substrate and Kapton tape were fabricated using a low cost and simple soft nano-lithography technique and the colorimetry and imaging of the fabricated 2D samples were investigated using this experimental setup.

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ta charset="UTF-8" >In This paper a ground-state cooling method for bad optomechanical systems is proposed. Previous authors show that an optical cavity with equal loss and gain has a parity-time reversal (PT) symmetry. We introduced an optomechanical cavity coupled to the two modes of a PT symmetry and a passive optical cavity. A quarter-wave plate provides linear mixing interaction between the PT symmetry and passive cavities. In this study, our proposed system improved the cooling rate by utilizing two effects: energy localization and quantum interference. These two impacts increase the cooling rate while the system is red or blue-detuned. It is demonstrated that optomechanical cooling occurs in both the bad-cavity limit and the weak optomechanical coupling regime. These innovations can be attained by parameter management of the system.

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In this work, a two-dimensional square periodic array was successfully transferred onto a rigid glass substrate during an innovative and simple-design two-step process of pattern transferring using Kapton tape and plasma technology. Flexible and stretchable, Kapton tape was selected for pattern transferring onto the glass for the first time herein; in parallel, the vacuum plasma treatment was utilized to improve surface adhesion properties and aid the pattern transferring process. The proposed 2D square plasmonic array supported the plasmon-induced transparency (PIT) phenomenon, which is caused by the excitation of surface plasmon resonances. The current study simulated the fabricated plasmonic structure using the finite-difference time-domain (FDTD) method and investigated the propagation of surface plasmon polariton (SPP) and cavity modes which enhanced transmission. This fabrication technique can offer new insights for micro/nanofabrication technology.

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The measurement of magnetic field generated by heart activity is crucial for the diagnosis and treatment of heart diseases and failures. Atomic magnetometers are an excellent choice for detecting bio-magnetic fields due to their comparable sensitivity to superconducting quantum interference devices, lower manufacturing costs, and lack of requirement for low temperatures. These magnetometers detect the magnetic field resulting from heart activity by measuring the Zeeman energy splitting and changes in laser light intensity as it passes through an alkali metal vapor cell. To improve the sensitivity of the measurements, this study presents a gradiometer design that utilizes two atomic magnetometers to eliminate environmental magnetic noise. By using a derivative technique, the homogeneous noises in both magnetometer channels are effectively eliminated. The gradiometer is capable of detecting the magnetic field produced by a frog's heart with a sensitivity of 860 fT/√Hz even without magnetic shielding and in the presence of the Earth's field. This gradiometer design can be expanded to include multiple channels for mapping the heart's magnetic field.

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Color vision deficiency (CVD), or color blindness, is a prevalent ocular disorder that hinders the recognition of different colors, affecting many people worldwide (8−10% of males and 0.4−0.5% of females). Recently, there has been a significant focus on plasmonic nanostructures as an alternative to chemical dyes for managing color blindness due to their remarkable characteristics and the tunability of plasmonic resonances. In this work, the plasmonic glasses based on silver nanoparticles with a TiO₂ thin layer coating were fabricated using the sputtering technique and proposed for blue-yellow (tritanopia) CVD management. The proposed plasmonic glasses based on silver nanoparticles are more selective than commercial Enchroma glasses because of the tunability of plasmonic properties of silver nanoparticles by controlling their morphology, which provides insights for applications of color vision deficiency improvement. Also, the antibacterial activity of the proposed plasmonic glasses based on silver nanoparticles was investigated against E. coli and S. aureus bacteria, which have exhibited effective antibacterial properties. The results indicate that the silver nanoparticle-based glasses not only aid in tritanopia management but also offer potential for antibacterial applications such as implant coatings.