Archives 2022

News On Atomic Magnetometers

The Journal of IEEE Sensors Letters published a paper entitled as “Microfabricated shaped rubidium vapor cell for miniaturized atomic magnetometers”

Abstract:In this letter, we present a novel microfabricated shaped rubidium vapor cell with 3 cm optical path length for miniaturized atomic magnetometers. The novel shaped rubidium vapor cells are manufactured by a wafer-level fabrication process, and the process consists of the following three steps sequentially: first, wet etching to form oblong shallow cavity arrays; second, anodic bonding, glass reflowing, and wet etching to obtain a glass wafer with shaped structures; third, anodic bonding and chemical reaction to obtain the wafer-level shaped rubidium vapor cells. A miniaturized atomic magnetometer using the novel shaped rubidium vapor cell is characterized in the geomagnetic environment. The performance of the novel shaped rubidium vapor cell is compared with the traditional microfabricated rubidium vapor cell of a “glass–silicon–glass” sandwich structure. Results show that the measured geomagnetic field is 47.85 μT. It is demonstrated that the dispersive signal’s slope of the novel shaped rubidium vapor cell is 15 times larger than that of the traditional one. Results also indicate that the miniaturized atomic magnetometer working in the geomagnetic environment has a magnetic noise spectral density of 3.5 pT/Hz ^1/2 from 1 to 2 Hz.

Congratulations for our new paper in Journal Of Scientific Reports

Streptozotocin‑induced Alzheimer’s disease investigation by one‑dimensional plasmonic grating chip

Hussam Jawad Kadhim, Haider Al‑Mumen, H. H. Nahi & S. M. Hamidi*

Recently, there has been signifcant interest in researching brain insulin resistance as it has been hypothesized that it may play a role in the progression of Alzheimer’s disease. Alzheimer’s disease (AD) is brain dementia that contributes to damage to the neuron cells and then patient death. This dementia is ranked as the ffth more dangerous disease in the world. Streptozotocin (STZ) is used to induce Alzheimer’s disease experimentally. STZ is toxic to the pancreatic beta cells and induces insulin resistance. Neuroplasmonin techniques have been used to investigate the ability of STZ on the activity of cultured neuron cells. Neuroplasmonic is a novel technology that combines nanotechnology and biosensor. This technique has been used to record neuron signals in vivo and in vitro. Also, it has many facilities such as label‑free detection, real‑time analysis, biological compatibility, small sample, high throughput, and low detection limit. In this paper, we introduce a one‑dimensional electro‑plasmonic nanograting platform that consists of a straight nanorod of gold embedded in a dielectric layer of polycarbonate. The chip is connected with an externally applied voltage to induce tunable PIT and increase the sensor sensitivity. To evaluate the sensing performance of the electro‑plasmonic sensor, this chip was cultured with Human Nucleus Pulposus Cells (HNPC). The first step was to measure the neuron cell activity in a healthy case. The next step was to measure the activity of neuron cells injected with different concentrations of STZ (0.5, 1, 2 mM) to induce the formation of Alzheimer’s disease in the cultured neuron cells. The results indicated that the electro‑plasmonics sensor had a high sensitivity to the cells’ activity and showed good results for the effecting STZ on the neuron cell’s activities.

News On Multiple Lasers

In these days, the Journal of Scientific Reports published a new paper entitled as “Frequency stabilization of multiple lasers to a reference atomic transition of Rb”

Modern atomic clocks based on the interrogation of an atomic transitions in the optical regions require multiple lasers at different wavelength for producing atomic ions, trapping and laser cooling of neutral atoms or atomic ions. In order to achieve highest efficiency for laser cooling or any other atomic transition, frequencies of each of the lasers involved need to be stabilized by mitigating its drifts or fluctuations arise due to ambient temperature variation or other kind of perturbations. The present article describes simultaneous frequency stabilization of multiple number of lasers, required for production and laser cooling of ytterbium (171Yb) ions, to a reference transition frequency of rubidium (Rb) atoms. In this technique, a diode laser operating at ~ 780 nm is frequency stabilized to one of the Doppler broadening-free absorption peak of rubidium atoms (85Rb) and then used as a reference frequency for calibrating a wavelength meter and subsequent simultaneous frequency stabilization of four lasers operating at different wavelengths.

News on Quantum Photonics

In these days, the Journal of Scientific reports published a new paper entitled as”Strain tunable quantum emission from atomic defects in hexagonal boron nitride for telecom-bands”

This study presents extending the tunability of 2D hBN Quantum emitters towards telecom (C-band − 1530 to 1560 nm) and UV-C (solar blind − 100 to 280 nm) optical bands using external strain inducements, for long- and short-range quantum communication (Quantum key distribution (QKD)) applications, respectively. Quantum emitters are the basic building blocks of this QKD (quantum communication or information) technologies, which need to emit single photons over room temperature and capable of tuning the emission wavelength to the above necessary range. Recent literature revealed that quantum emitters in 2D hBN only has the ability to withstand at elevated temperatures and aggressive annealing treatments, but density functional theory (DFT) predictions stated that hBN can only emit the single photons from around 290 to 900 nm (UV to near-IR regions) range. So, there is a need to engineer and further tune the emission wavelength of hBN quantum emitters to the above said bands (necessary for efficient QKD implementation). One of the solutions to tune the emission wavelength is by inducing external strain. In this work, we examine the tunability of quantum emission in hBN with point defects by inducing three different normal strains using DFT computations. We obtained the tunability range up to 255 nm and 1589.5 nm, for the point defects viz boron mono vacancies (V_B) and boron mono vacancies with oxygen atoms (V_BO₂) respectively, which can enhance the successful implementation of the efficient QKD. We also examine the tunability of the other defects viz. nitrogen mono vacancies, nitrogen mono vacancy with self-interstitials, nitrogen mono vacancy with carbon interstitials, carbon dimers and boron dangling bonds, which revealed the tunable quantum emission in the visible, other UV and IR spectrum ranges and such customized quantum emission can enhance the birth of other quantum photonic devices.

News On Smart contact lenses

The Journal of Nature Communications published a paper entitled as “Wearable smart sensor systems integrated on soft contact lenses for wireless ocular diagnostics”

Wearable contact lenses which can monitor physiological parameters have attracted substantial interests due to the capability of direct detection of biomarkers contained in body fluids. However, previously reported contact lens sensors can only monitor a single analyte at a time. Furthermore, such ocular contact lenses generally obstruct the field of vision of the subject. Here, we developed a multifunctional contact lens sensor that alleviates some of these limitations since it was developed on an actual ocular contact lens. It was also designed to monitor glucose within tears, as well as intraocular pressure using the resistance and capacitance of the electronic device. Furthermore, in-vivo and in-vitro tests using a live rabbit and bovine eyeball demonstrated its reliable operation. Our developed contact lens sensor can measure the glucose level in tear fluid and intraocular pressure simultaneously but yet independently based on different electrical responses.

News on Energy Harvesting

In these days, the Journal of Materials Chemistry A published a new paper entitled as “Energy harvesting of fully-flexible magnetoelectric composites using a piezoelectric P(VDF-TrFE) and magnetostrictive CoFe2O4 nanofiber”

In response to the increasing demand for wearable devices, the development of flexible energy harvesters as self-powering systems to replace batteries is accelerating. Flexible magnetoelectric (ME) composites, which can convert practical electrical energy from a magnetic field source, have attracted considerable attention for application in wearable magnetic devices. In this study, a 2-2 type structure based on a flexible magnetostrictive film with cobalt ferrite (CoFe2O4, CFO) nanofibers was adopted to obtain appropriate flexibility and magnetoelectric properties. The flexible ME composite was completely fabricated by coating piezoelectric poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) onto a magnetostrictive film composed of CFO nanofibers and a polyimide matrix. Moreover, we conducted a multiphysics simulation and theoretically proved that a higher strain could be transferred to the piezoelectric layer at higher CFO concentrations, thus resulting in the generation of high magnetoelectric signals from the ME composite. The flexible, robust, and mechanically-stable ME composite reached an output voltage of 0.52 V and a current signal of 25 nA under an external AC magnetic field at 1 Hz. This study led to the development of a fully-flexible design of a bilayer ME composite prepared using a simple fabrication process providing a future avenue for wearable magnetoelectric energy harvesting.

Congratulations for our new Paper in Journal Of ACS Applied Nano Materials

Congratulations for our new Paper in Journal Of ACS Applied Nano Materials:

Plasmonic Eyeglasses Based on Gold Nanoparticles for Color Vision Deficiency Management
N. Roostaei and S. M. Hamidi*

Color vision deficiency (CVD), or color blindness, is a common ocular disorder that prohibits the recognition of different colors, from which many people suffer worldwide (8-10% of males and 0.4-0.5% of females). Despite numerous efforts, no definitive cure for color blindness has yet been discovered, but many color filter-based aids such as tinted glasses and contact lenses have been developed to help color blind people. This work is the first to fabricate plasmonic eyeglasses based on gold nanoparticles using two innovative methods, i.e., the simple self-assembly technique and heat treatment of gold thin films, and to evaluate them for color blindness management. The proposed plasmonic eyeglasses were simulated using the finite-difference time-domain (FDTD) method, and a good agreement between experimental and simulation results was obtained. The proposed plasmonic eyeglasses based on gold nanoparticles are more selective than commercial Enchroma and VINO glasses because of the tunability of plasmonic properties of gold NPs by controlling their morphology, which provides insights for applications of color vision deficiency improvement.

کارگاه آموزش نرم افزار طراحی اپتیکی زیمکس

پژوهشکده لیزر و پلاسمای دانشگاه شهید بهشتی کارگاه آموزشی نرم افزار طراحی سامانه های اپتیکی

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09399119912 شماره تماس جهت ثبت نام

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soheila.akbari.sbu@gmail.com

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مرکز فناوری کوانتومی دانشگاه شهید بهشتی تهران برگزار می کند: سمینار آشکارسازهای تک فوتون

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News On Plasmonic Switches

In these days, the Journal of Plasmonics published a new paper entitled as “Switchable Gratings for Ultracompact and Ultrahigh Modulation Depth Plasmonic Switches”

Plasmonic interconnects present a compact platform for high modulation-depth optical switches. Conventional plasmonic switching approaches depend on modifying the dispersion of the surface plasmon polariton (SPP) wave at the metal/dielectric interface. Here, we introduce a novel scheme for ultracompact and high modulation depth (MD) plasmonic switching using a phase-change material-based switchable grating consisting of antimony trisulfide (Sb2S3). In its ON state, the switchable grating excites surface plasmon polaritons (SPP) and bulk plasmon polaritons (BPPs) in plasmonic films and hyperbolic metamaterials (HMMs), respectively. The SPP switch has a footprint of 23.1 µm2 and a MD of up to 40 dB. The BPP switch has a footprint of 13.12 μm2 and a MD of 29.7 dB. The BPP switch enjoys a broadband MD from 299 to 375 THz. Concurrently, we show that the same switchable grating on plasmonic film and on HMM is a refection-based optical switch. Finally, we present a novel scheme for non-local control over the spontaneous emission rate and out-coupled power from emitters embedded in HMMs.