Papers by Mahboubeh Dolatyari
Optical and Quantum Electronics
Scientific Reports, Jun 24, 2023
Multiphoton absorbing upconversion nanoparticles are emerging as bioimaging materials but are lim... more Multiphoton absorbing upconversion nanoparticles are emerging as bioimaging materials but are limited by the low quantum yield of their visible fluorescence. This article contains colloids of graphene quantum dots (GQDs), Neodymium, and Cobalt doped Graphene Quantum dots (Co-GQDs and Nd-GQDs) surrounded by carboxylic acids are synthesized which especially are suitable for bio applications; in this way, carboxylic acid groups exchanged by Amoxicillin as an antibiotic with bactericidal activity. The XRD diffraction method, TEM microscope, UV-Vis, and photoluminescence spectroscopies characterize the synthesized materials. The synthesized Quantum dots (QDs) exhibit upconversion properties and their emission is centered at 480 nm, but a red shift was observed with the increase of the excitation wavelength. In the emission spectra of synthesized QDs that can be related to the defect levels introduced by passivation of the QDs in the structure, the results show that with the interaction of the surface QDs with more carboxylic groups, the redshift is not observed. As the results indicate an increase in the intensity of upconversion emission is recorded for Co-GQDs and Nd-GQDs. The absolute quantum efficiency (QY) for Co-GQDs and Nd-GQDs were determined to be 41% and 100% more than GQDs respectively. DFT calculations indicate a strong bond between graphene and cobalt and Neodymium atoms. In doped materials, there are trap levels between the band gap of the GQDs which are responsible for increasing the intensity of the upconversion phenomenon. In recent years, graphene quantum dots (GQDs) have attracted much attention due to their unique structural and optoelectronic properties and their great potential in various applications in drug delivery 1-5 , sensors 6-12 , bio-imaging 13-18 , magnetic hyperthermia 19-21 , photothermal therapy 22-26 , antibacterial 23-28 , catalyst 29-33 , environmental protection 34,35 , energy conversion, spintronics, photovoltaic devices 36-53 has made a remarkable accomplishment. One of the important features of these nanoparticles is having high fluorescence properties that can be used for biological imaging and optical sensing. GQDs have attracted much attention as promising biomaterials due to their exceptional advantages of low cytotoxicity, excellent solubility, stable photoluminescence (PL), biocompatibility, and low cost 54-59. Conventional imaging probes, such as fluorescent dyes and fluorescent proteins, have attracted much attention. However, they face poor diagnostic sensitivity, instability, and high toxicity and have no therapeutic effect. It was difficult to find a dual-purpose material that could act as an imaging probe and a drug delivery at the same time. As an effective drug delivery, the fluorescent matrix should meet the following criteria: (1) effective drug delivery, (2) good biocompatibility, and (3) good circulation stability in vivo 60-63. Recently, the rapid development in nanomedicine has opened a new way to find such materials, and nanomaterials have become a very important topic in biomedical applications due to their great potential for the formulation of anticancer drugs. Engineered nanomaterials that have the effect of permeability, biocompatibility, and low toxicity can be used in biomedical applications, including biomedical diagnosis and disease treatment 64,65. Up conversions, nanoparticles (UCNPs) have anti-Stokes luminescence that can convert near-infrared (NIR) light into visible light. UCNPs have high chemical stability and can be used as fluorescence probes in a variety of complex organisms and facilitate the bioassay process. In addition, UCNPs can lead to surface conjugation with specific targeting ligands (such as peptides, antibodies, and small molecule drugs) and can be used as probes to
Optik, Oct 1, 2016
In this paper we present a full wave 3D-finite difference time domain (FDTD) optical and electric... more In this paper we present a full wave 3D-finite difference time domain (FDTD) optical and electrical simulation study of ultra thin silicon solar cell. We have analyzed the optical generation rate and absorption enhancement in thin film solar cell in which silver nanoparticles are embedded in the depletion region of p-n junction in the active layer of solar cell. Then we investigate efficiency and power output of solar cell by solving the Poisson and drift diffusion equations on a finite element mesh, by considering the extracted generation rate data from FDTD simulations. In this work localized surface plasmons (LSPs) are the key factor for absorption and electron-hole generation rate enhancement in thin film solar cell. We show that these enhancements result from dense near field provided by LSPs and ensuring that a large fraction of the incident optical power (which is considered to be AM1.5) dissipates in the absorbing active layer rather than in the MNPs. We study in detail the effect of metal nanoparticle (MNP) geometry in solar cell performance and optimize geometrical parameters of MNPs through particle swarm (PS) optimization algorithm. The optimized structure of spherical MNPs with a diameter of 70 nm and spacing of 180 nm, and optimized structure of nanorod MNPs with a diameter of 70 nm and center to center spacing of 190 nm and length of 150 nm which are imbedded in depletion layer, provided 32.83% and 39% improvements in the efficiency relative to the reference cell, respectively.
The main purpose of this paper is design of a carpet cloak to operate at visible wavelength range... more The main purpose of this paper is design of a carpet cloak to operate at visible wavelength range (500 to 700nm) using nanocomposite materials. The refractive index profile of the cloak region is calculated using an analytic function determined by standard conformal mapping. Since the refractive index for cloak region have to be between 0 and 1, and usually implementation of this range is hard, so, the cloak region is compacted as more as possible. Cloak region is divided into some pixels and the refractive index of each pixel is approximated as the refractive index value obtained by the mapping in the center of the pixel. To realize required refractive index, each pixel is considered as a polymeric medium with random distribution of spherical metal and doped semiconductor nanoparticles with desired plasma frequency and filling factor.
DOAJ (DOAJ: Directory of Open Access Journals), Mar 1, 2013
Highly crystalline Gd 3+-doped cadmium oxide micro-structure was synthesized by calcining the obt... more Highly crystalline Gd 3+-doped cadmium oxide micro-structure was synthesized by calcining the obtained precursor of a sol-gel reaction. The reaction was carried out with cadmium nitrate (Cd(NO 3) 2 •4H 2 O), gadolinium oxide, and ethylene glycol (C 2 H 6 O 2) reactants without any additives at 80°C for 2 h. The resulting gel was calcined at 900°C with increasing temperature rate of 15°C/min for 12 h in a furnace. As a result of heating, the organic section of the gel was removed, and the Gd 3+-doped cadmium oxide micro-structure was produced. The obtained compound from the sol-gel technique possesses a cubic crystalline structure at a micro scale. XRD study indicates that the obtained Gd 3+-doped CdO has a cubic phase. Also, the SEM images showed that the resulting material is composed of particles with cluster structure. Also, FT-IR spectroscopy was employed to characterize the Gd 3+-doped CdO micro-structures.
Physica B-condensed Matter, Mar 1, 2020
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Optik, Mar 1, 2017
In this work an all-optical switch based on array of metal nanoparticles (MNP), imbedded in a med... more In this work an all-optical switch based on array of metal nanoparticles (MNP), imbedded in a medium which shows Electromagnetically Induced Transparency (EIT), has been proposed. By implementing EIT in the host medium of MNP plasmonic waveguide, we can induce a transparency and alter the refractive index, by applying reasonable values of optical pumps. Using Finite-Difference Time-Domain (FDTD) simulation, it is found that the proposed all-optical switching exhibits femtosecond-scale feedback time. Results show that the response time of signal light switching up and down are about 100fs. The proposed switch has a signal transmission of about 14% for a chain of 20 silver MNPs with a length of about 3μm. It shows losses about 7.75dB/μm. The proposed nanoscale plasmonic switch has optical properties that cannot be achieved in any other ways at the nanometer scale, such as overcoming diffraction limit.
International Nano Letters, May 25, 2013
Highly crystalline Gd 3+-doped cadmium oxide micro-structure was synthesized by calcining the obt... more Highly crystalline Gd 3+-doped cadmium oxide micro-structure was synthesized by calcining the obtained precursor of a sol-gel reaction. The reaction was carried out with cadmium nitrate (Cd(NO 3) 2 •4H 2 O), gadolinium oxide, and ethylene glycol (C 2 H 6 O 2) reactants without any additives at 80°C for 2 h. The resulting gel was calcined at 900°C with increasing temperature rate of 15°C/min for 12 h in a furnace. As a result of heating, the organic section of the gel was removed, and the Gd 3+-doped cadmium oxide micro-structure was produced. The obtained compound from the sol-gel technique possesses a cubic crystalline structure at a micro scale. XRD study indicates that the obtained Gd 3+-doped CdO has a cubic phase. Also, the SEM images showed that the resulting material is composed of particles with cluster structure. Also, FT-IR spectroscopy was employed to characterize the Gd 3+-doped CdO micro-structures.
We investigate coupling and power transfer between two transverse modes in a single quantum-well ... more We investigate coupling and power transfer between two transverse modes in a single quantum-well traveling wave semiconductor optical amplifier (SOAs) by non-degenerate four wave mixing. By this approach the mode purity achieve 99.99% at the end of active region of SOA and the mode conversion can be controlled by the adjusting pump and probe power.
Austin journal of nanomedicine & nanotechnology, Apr 19, 2021
In this paper, a nano-metamaterial with the structure of Ag-SiO 2-PbTe is proposed that has a ran... more In this paper, a nano-metamaterial with the structure of Ag-SiO 2-PbTe is proposed that has a random arrangement in the host medium of expanded polystyrene (foam) for the realization of a broadband negative refractive index at the visible spectrum. The negative refractive index for the purposed metamaterial was obtained from the plasmonic resonance in the core and outer layer for both electric and magnetic components of light. Here, we use different radii for the outer layer of nanoparticles to create the broadband negative permeability. In this way, the doped semiconductor nanoparticles are included in the host medium to create the broadband negative permittivity. The overlap between the spectrum of the negative permittivity and permeability introduces the broadband negative refractive index at the visible band. The novel introduced structure creates the broadband negative refractive index and it is simple and practical for fabrication. For the realization of the proposed material, synthesis and characterization of the designed nanocomposite structure are investigated. To this end, the absorption and the transmission coefficients of the synthesized material are measured and compared with theoretical results. The obtained results indicate that the numerical simulations using Mie theory have good agreement with the experimental results.
Optical and Quantum Electronics, Nov 25, 2016
In this research work, composite media based on metamaterials including random distribution of sp... more In this research work, composite media based on metamaterials including random distribution of spherical nanoparticles in a polymeric foam host are suggested to achieve negative effective refractive index in the visible spectrum. For this purpose structures including single, two and three layer spherical particles are investigated. Based on simulation results, media including single layer spheres (metallic and dielectric particles) and two layer nanospheres (core-shell particles consist of metallic core and dielectric shell) based on superposition of nanoparticles with different sizes and fill fractions are proposed for desired result. In this work, to obtain optimized band with negative RI media, superposition of three layer nanoparticles and doped semiconductor are designed.
Journal of Materials Chemistry C, 2019
The ongoing quest to find methods to control the trap states in solution processed nanostructures... more The ongoing quest to find methods to control the trap states in solution processed nanostructures (trap engineering) will revolutionise the applications of nanomaterials for optoelectronic purposes.
This paper proposes a novel ring resonator based optical filter that has an outstanding multi nar... more This paper proposes a novel ring resonator based optical filter that has an outstanding multi narrow band response due to adopting quasi structures such as Thue-Morse sequence as the radius-pattern. This capability introduces this design approach as an effective method for the design of filters for emerging dense wavelength division multiplexing networks. The design process incorporates analysing through the transfer matrix method and the powerful discrete-time signal processing techniques. Giving an adequate overview of analysing basic optical building blocks in the Z-domain, the procedure develops to analysing any optical structure imposed by mathematical sequences. The proposal is discussed employing pole-zero diagrams, discrete-time signal processing approach including apodization techniques. The point of the discrete-time signal processing approach is that the effect of dominant optical parameters over operation is clarified through the pole-zero position. Features like number of poles, bandwidth, and position of stop-bands can be controlled using ring diameter ratio. Finally, apodization of coupling coefficients attains a filter with an FWHM of 0.3 nm.
In this paper, a composite medium based metamaterial with random distribution of nanoparticles in... more In this paper, a composite medium based metamaterial with random distribution of nanoparticles in vacuum host to achieve negative effective refractive index in the visible wavelength range is suggested for invisibility purposes. Our calculations show that structures including single metal (dielectric) spheres and core-shell structures with metallic core and dielectric shell, which consists two-layer particles with uniform sizes cannot support negative effective refractive index. For this purpose the structures consist of two-layer nanospheres with different sizes and fill fraction has been proposed. Since, band width of negative refractive index is narrow, the three layer nanospheres has been studied and investigated. We show that in this case with increasing the refractive index of middle and outer layers, negative value of effective refractive index can be increased. Also, we show that using different sizes of nanomaterials in host medium, band width is increased. Finally, superposition of three layer spherical nanoparticles with different outer radius and applied single doped semiconductor spheres, has been proposed. We show that Band width with negative permittivity and permeability can be optimized.
Optical and Quantum Electronics, Aug 1, 2021
We report that the organic photovoltaic (OPV) performance of wide band gap pyridopyridinedithioph... more We report that the organic photovoltaic (OPV) performance of wide band gap pyridopyridinedithiophene-based conjugated polymers can be significantly improved by employing the random terpolymer approach for the development of new pyridopyridinedithiophene-based conjugated polymers. This is demonstrated by the synthesis of the alternating copolymer (P1) consisting of 3,3'-difluoro-2,2'-bithiophene and after the addition of chloronaphthalene (CN) to the chloroform processing solvent which significantly limited the short circuit current density (J SC), fill factor (FF) and overall performance of the prepared photovoltaic devices. On the other hand, P2 based films showed better miscibility with the acceptor particularly when processed using 5% CN containing chloroform solvent giving a respectable improvement in the PCE of the photovoltaic devices.
Optics and Photonics Society of Iran, Feb 10, 2017
The main goal of this research is design of an ultraviolet photodetector based on intersubband tr... more The main goal of this research is design of an ultraviolet photodetector based on intersubband transitions in III-Nitride multiple quantum well. Due to the abundance of visible light detectors, optically pumped lasers with ability of converting incident ultraviolet radiation to visible light are proposed. In this way, incident wavelength of about 352nm at ultraviolet wavelength band is converted to wavelength of 559nm at visible range using intersubband transitions in III-Nitride multiple quantum well structures.To calculate parameters of the structure, wave functions and energy levels are obtained by solving 1-D Schrodinger-Poisson equation self consistently at 300°K. Responsivity and optical gain for the designed structure are 4.623(mA/w) and 10.28 (1/cm) at 300°K respectively.
In this paper we have studied polymeric structures which possess coated spherical nanoparticles i... more In this paper we have studied polymeric structures which possess coated spherical nanoparticles in visible wavelength range. Medium with metallic cores and silicon (Si) shells and structures composed by Si cores and metallic shells have been studied. Since, the size of particles is very small related to the incident wavelength, semi-static approximation and Clausius-Mossotti formula have been used in order to calculate the effective permittivity. Resonance wavelength of the structure depends on size and filling fraction of the guest nanoparticles. Resonance wavelength has been obtained by the mathematical relations and simulation results. Studied structures are applicable in invisibility.
Sensor Letters, Dec 1, 2016
In this paper, we introduce a micro-ring resonator-based highly sensitive carbon dioxide sensor. ... more In this paper, we introduce a micro-ring resonator-based highly sensitive carbon dioxide sensor. For this purpose, a valley is created in the core of the ring and PbSe quantum dots (QDs) are deposited in the valley and the sensor is exposed to CO2 gas. In this way, the refractive index of the PbSe QDs increases with an increase in the concentration of gas flow, and then the resonance frequency of the ring resonator shifts. The designed sensor operates almost linearly over a wide range of concentrations for CO2 gas and shows a high resonance shift at different concentrations of CO2 gas. The detection limit for the designed sensor is 0.001% of CO2 gas which is more sensitive than previously reported sensors based on microring resonators. The frequency shifts are investigated by changing the width of the valley. The minimum width of the valley was determined for the evanescent field in which only the outer core of the ring affects the resonant frequency. Also, the modal analysis of the...
Scientific Reports
In this paper, we synthesized Ag/ZnO composite colloidal nanoparticles and the surface of nanopar... more In this paper, we synthesized Ag/ZnO composite colloidal nanoparticles and the surface of nanoparticles was improved by amodiaquine ligand. The synthesized nanoparticles were characterized using the XRD diffraction pattern, FT-IR Spectroscopy, TEM image, and UV–Vis spectroscopy. The antibacterial, antifungal, and antiviral effects of the synthesized colloid were examined on E.coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Enterococcus hirae bacteria, and Candida Albicans and form spore aspergillus fungi, also influenza, herpes simplex, and covid 19 viruses. The results indicate more than 7 log removal of the bacteria, fungi, and viruses by synthesized colloid with a concentration of 15 μg/L (Ag)/50 µg/ml (ZnO). This removal for covid 19 virus is from 3.2 × 108 numbers to 21 viruses within 30 s. Also, irritation and toxicity tests of the synthesized colloid show harmless effects on human cells and tissues. These colloidal nanoparticles were used as mouthwash solution and th...
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Papers by Mahboubeh Dolatyari