Nanostructured Tungsten Disulfide WS2 as Mie Scatterers and Nanoantennas

MRS Advances ◽  
2020 ◽  
Vol 5 (35-36) ◽  
pp. 1819-1826 ◽  
Author(s):  
Hasan Ahmed ◽  
Viktoriia E. Babicheva
Keyword(s):  
Refractive Index ◽  
Near Infrared ◽  
Spectral Response ◽  
Van Der Waals ◽  
Transition Metal Dichalcogenides ◽  
Silicon Layer ◽  
High Refractive Index ◽  
Tungsten Disulfide ◽  
Optical Elements ◽  
Wide Range

ABSTRACTNanoparticles of high-refractive-index materials like semiconductors can achieve confinement of light at the subwavelength scale because of the excitation of Mie resonances. The nanostructures out of high-refractive-index materials have extensively been studied theoretically and realized in experiments exploring a wide range of photonic applications. Recently, transition metal dichalcogenides (TMDCs) from the family of van der Waals layered materials have been shown to exhibit tailorable optical properties along with high refractive index and strong anisotropy. We envision that TMDCs are a promising material platform for designing metasurfaces and ultra-thin optical elements: these van der Waals materials show a strong spectral response on light excitations in visible and near-infrared ranges, and metasurface properties can be controlled by nanoantenna dimensions and their arrangement. In this work, we investigate a periodic array of disk-shaped nanoantennas made of a TMDC material, tungsten disulfide WS2, placed on top of a silicon layer and oxide substrate. We show that the nanostructure resonance in TMDC disk-shaped nanoantenna array can be controlled by the variation in silicon layer thickness and have a dependence on the presence of index-match superstrate cover. We also report on the spectral features in absorption and reflection profiles of the same structure with different surrounding index.

scholarly journals Sodium Alginate Cross-Linkable Planar 1D Photonic Crystals as a Promising Tool for Pb2+ Detection in Water

Chemosensors ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 37 ◽  
Author(s):  
Andrea Dodero ◽  
Paola Lova ◽  
Silvia Vicini ◽  
Maila Castellano ◽  
Davide Comoretto
Keyword(s):  
Refractive Index ◽  
Photonic Crystals ◽  
Sodium Alginate ◽  
Spectral Response ◽  
High Refractive Index ◽  
Polluted Water ◽  
Ionic Exchange ◽  
Promising Tool ◽  
Rural Environments ◽  
First Time

Due to its high toxicity, Pb2+ pollution is a serious threat for human health and environments. However, in situ real-time detection of Pb2+ pollution is difficult and laboratory instruments are usually required. Then, the possibility to monitor water quality without laboratory instruments could lead to the extensive assessment of polluted water sources, especially in rural environments and developing countries where large lead concentrations are often found in surface water. Consequently, new simple colorimetric sensors are highly interesting in the field. In this work we report for the first time disposable polymer planar 1D photonic crystals made of poly (N-vinylcarbazole) as high refractive index medium and sodium alginate as low refractive index and active medium for the detection of Pb2+ in water. The detection relies on the ionic exchange occurring into the alginate matrix. This process effectively induces a physical cross-linking phenomenon, which inhibits water solubilization of the polymer. In turn, this affects the spectral response of the planar 1D photonic crystals modifying its color.

scholarly journals Tungsten disulfide-based nanocomposites for photothermal therapy

2019 ◽  
Vol 10 ◽  
pp. 811-822 ◽  
Author(s):  
Tzuriel Levin ◽  
Hagit Sade ◽  
Rina Ben-Shabbat Binyamini ◽  
Maayan Pour ◽  
Iftach Nachman ◽  
...  
Keyword(s):  
Photothermal Therapy ◽  
Near Infrared ◽  
Transition Metal Dichalcogenides ◽  
Tungsten Disulfide ◽  
Ceric Ammonium Nitrate ◽  
Infrared Range ◽  
Metal Dichalcogenides ◽  
Current Article ◽  
Functionalized Nanotubes

Nanostructures of transition-metal dichalcogenides (TMDC) have raised scientific interest in the last few decades. Tungsten disulfide (WS2) nanotubes and nanoparticles are among the most extensively studied members in this group, and are used for, e.g., polymer reinforcement, lubrication and electronic devices. Their biocompatibility and low toxicity make them suitable for medical and biological applications. One potential application is photothermal therapy (PTT), a method for the targeted treatment of cancer, in which a light-responsive material is irradiated with a laser in the near-infrared range. In the current article we present WS2 nanotubes functionalized with previously reported ceric ammonium nitrate–maghemite (CAN-mag) nanoparticles, used for PTT. Functionalization of the nanotubes with CAN-mag nanoparticles resulted in a magnetic nanocomposite. When tested in vitro with two types of cancer cells, the functionalized nanotubes showed a better PTT activity compared to non-functionalized nanotubes, as well as reduced aggregation and the ability to add a second-step functionality. This ability is demonstrated here with two polymers grafted onto the nanocomposite surface, and other functionalities could be additional cancer therapy agents for achieving increased therapeutic activity.

scholarly journals Wide Range Refractive Index Sensor Using a Birefringent Optical Fiber

2021 ◽  
Author(s):  
Moutusi De ◽  
Vinod Kumar Singh
Keyword(s):  
Refractive Index ◽  
Near Infrared ◽  
High Sensitivity ◽  
Infrared Region ◽  
Device Fabrication ◽  
Refractive Index Sensor ◽  
Potential Candidate ◽  
Wide Range ◽  
Analyte Detection ◽  
Birefringent Optical Fiber

Abstract In this article, an efficient high birefringent D-shaped photonic crystal fiber (HB-D-PCF) plasmonic refractive index sensor is reported. It is able to work over a long low refractive index (RI) analyte range from 1.29 to 1.36. This modified simple structured hexagonal PCF has high birefringence in the near-infrared region. A thin gold film protected by a titanium dioxide (TiO2) layer is deposited on the D-surface of the PCF which acts as surface plasmon active layer. The sensor consists of an analyte channel on the top of the fiber. The performance of the HB-D-PCF is analyzed based on finite element method (FEM). Both wavelength and amplitude interrogation techniques are applied to study the sensing performance of the optimized sensor. Numerical results show wavelength and amplitude sensitivity of 9245nm/RIU and 1312 RIU-1 respectively with high resolution. Owing to the high sensitivity, long range sensing ability as well as spectral stability the designed HB-D-PCF SPR sensor is a potential candidate for water pollution control, glucose concentration testing, biochemical analyte detection as well as portable device fabrication.

scholarly journals Wafer scale synthesis of organic semiconductor nanosheets for van der Waals heterojunction devices

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Sirri Batuhan Kalkan ◽  
Emad Najafidehaghani ◽  
Ziyang Gan ◽  
Fabian Alexander Christian Apfelbeck ◽  
Uwe Hübner ◽  
...  
Keyword(s):  
Organic Semiconductors ◽  
Physical Vapor Deposition ◽  
Field Effect Transistors ◽  
Van Der Waals ◽  
Transition Metal Dichalcogenides ◽  
Wafer Scale ◽  
Heterojunction Devices ◽  
Wide Range ◽  
Conformal Electronics ◽  
Metal Dichalcogenides

AbstractOrganic semiconductors (OSC) are widely used for consumer electronic products owing to their attractive properties such as flexibility and low production cost. Atomically thin transition metal dichalcogenides (TMDs) are another class of emerging materials with superior electronic and optical properties. Integrating them into van der Waals (vdW) heterostructures provides an opportunity to harness the advantages of both material systems. However, building such heterojunctions by conventional physical vapor deposition (PVD) of OSCs is challenging, since the growth is disrupted due to limited diffusion of the molecules on the TMD surface. Here we report wafer-scale (3-inch) fabrication of transferable OSC nanosheets with thickness down to 15 nm, which enable the realization of heterojunction devices. By controlled dissolution of a poly(acrylic acid) film, on which the OSC films were grown by PVD, they can be released and transferred onto arbitrary substrates. OSC crystal quality and optical anisotropy are preserved during the transfer process. By transferring OSC nanosheets (p-type) onto prefabricated electrodes and TMD monolayers (n-type), we fabricate and characterize various electronic devices including unipolar, ambipolar and antiambipolar field-effect transistors. Such vdW p-n heterojunction devices open up a wide range of possible applications ranging from ultrafast photodetectors to conformal electronics.

scholarly journals One-step vapor-phase synthesis of transparent high refractive index sulfur-containing polymers

2020 ◽  
Vol 6 (28) ◽  
pp. eabb5320 ◽  
Author(s):  
Do Heung Kim ◽  
Wontae Jang ◽  
Keonwoo Choi ◽  
Ji Sung Choi ◽  
Jeffrey Pyun ◽  
...  
Keyword(s):  
Refractive Index ◽  
Vapor Phase ◽  
Elemental Sulfur ◽  
Chemical Vapor ◽  
Deposition Process ◽  
High Refractive Index ◽  
Visible Range ◽  
Wide Range ◽  
One Step ◽  
Vapor Phase Synthesis

High refractive index polymers (HRIPs) have recently emerged as an important class of materials for use in a variety of optoelectronic devices including image sensors, lithography, and light-emitting diodes. However, achieving polymers having refractive index exceeding 1.8 while maintaining full transparency in the visible range still remains formidably challenging. Here, we present a unique one-step vapor-phase process, termed sulfur chemical vapor deposition, to generate highly stable, ultrahigh refractive index (n > 1.9) polymers directly from elemental sulfur. The deposition process involved vapor-phase radical polymerization between elemental sulfur and vinyl monomers to provide polymer films with controlled thickness and sulfur content, along with the refractive index as high as 1.91. Notably, the HRIP thin film showed unprecedented optical transparency throughout the visible range, attributed to the absence of long polysulfide segments within the polymer, which will serve as a key component in a wide range of optical devices.

scholarly journals Plasmonic Sensing Characteristics of Gold Nanorods with Large Aspect Ratios

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3458 ◽  
Author(s):  
Chao Zhuang ◽  
Yifan Xu ◽  
Ningsheng Xu ◽  
Jinxiu Wen ◽  
Huanjun Chen ◽  
...  
Keyword(s):  
Refractive Index ◽  
Gold Nanorods ◽  
High Performance ◽  
Near Infrared ◽  
High Refractive Index ◽  
Surface Enhanced Raman Spectroscopy ◽  
Sers Substrate ◽  
Refractive Index Sensitivity ◽  
Aspect Ratios ◽  
Plasmonic Sensing

Plasmonic gold nanorods play important roles in nowadays state-of-the-art plasmonic sensing techniques. Most of the previous studies and applications focused on gold nanorods with relatively small aspect ratios, where the plasmon wavelengths are smaller than 900 nm. Gold nanorods with large aspect ratios are predicted to exhibit high refractive-index sensitivity (Langmir 2008, 24, 5233–5237), which therefore should be promising for the development of high-performance plasmonic chemical- and bio-sensors. In this study, we developed gold nanorods with aspect ratios over 7.9, which exhibit plasmon resonances around 1064 nm. The refractive index (RI) sensitivity of these nanorods have been evaluated by varying their dielectric environment, whereby a sensitivity as high as 473 nm/RIU (refractive index unit) can be obtained. Furthermore, we have demonstrated the large-aspect-ratio nanorods as efficient substrate for surface enhanced Raman spectroscopy (SERS), where an enhancement factor (EF) as high as 9.47 × 108 was measured using 4-methylbenzenethiol (4-MBT) as probe molecule. Finally, a type of flexible SERS substrate is developed by conjugating the gold nanorods with the polystyrene (PS) polymer. The results obtained in our study can benefit the development of plasmonic sensing techniques utilized in the near-infrared spectral region.

scholarly journals Attenuated Total Reflection at THz Wavelengths: Peculiarities of Total Internal Reflection and Polariscopy

2021 ◽  
Author(s):  
Meguya Ryu ◽  
Soon Hock Ng ◽  
Vijayakumar Anand ◽  
Stefan Lundgaard ◽  
Jingwen Hu ◽  
...  
Keyword(s):  
Refractive Index ◽  
Biological Samples ◽  
Total Internal Reflection ◽  
Refractive Index Change ◽  
High Refractive Index ◽  
Total Reflection ◽  
Attenuated Total Reflection ◽  
Internal Reflection ◽  
Optical Elements ◽  
Frustrated Total Internal Reflection

Capabilities of the Attenuated Total Reflection (ATR) at THz wavelengths for increased sub-surface depth characterisation of (bio-)materials is presented. The penetration depth of a THz evanescent wave in biological samples is dependent on the wavelength and temperature and can reach 0.1-0.5 mm depth due to strong refractive index change ∼0.4 of the ice-water transition; this is quite significant and important when studying biological samples. Technical challenges are discussed when using ATR for uneven, heterogeneous, high refractive index samples with possibility of frustrated total internal reflection (a breakdown of the ATR reflection-mode into transmission-mode). Local field enhancements at the interface are discussed with numerical/analytical examples. Maxwell’s scaling was used to model behaviour of absorber-scatterer inside materials at the interface with ATR prism for realistic complex refractive indices of bio-materials. Modality of ATR with polarisation analysis is proposed and its principle illustrated, opening an invitation for its experimental validation. The sensitivity of the polarised ATR mode to the refractive index between the sample and ATR prism is revealed. Design principles of polarisation active optical elements and spectral filters are outlined. The results and concepts are based on experiments carried out at the THz beamline of the Australian Synchrotron.

scholarly journals Broadband Optical Properties of Atomically Thin PtS2 and PtSe2

Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3269
Author(s):  
Georgy A. Ermolaev ◽  
Kirill V. Voronin ◽  
Mikhail K. Tatmyshevskiy ◽  
Arslan B. Mazitov ◽  
Aleksandr S. Slavich ◽  
...  
Keyword(s):  
Optical Properties ◽  
Optical Constants ◽  
Transition Metal Dichalcogenides ◽  
Optoelectronic Device ◽  
High Refractive Index ◽  
Broadband Absorption ◽  
Wide Range ◽  
Out Of Plane ◽  
Metal Dichalcogenides ◽  
Infrared Wavelengths

Noble transition metal dichalcogenides (TMDCs) such as PtS2 and PtSe2 show significant potential in a wide range of optoelectronic and photonic applications. Noble TMDCs, unlike standard TMDCs such as MoS2 and WS2, operate in the ultrawide spectral range from ultraviolet to mid-infrared wavelengths; however, their properties remain largely unexplored. Here, we measured the broadband (245–3300 nm) optical constants of ultrathin PtS2 and PtSe2 films to eliminate this gap and provide a foundation for optoelectronic device simulation. We discovered their broadband absorption and high refractive index both theoretically and experimentally. Based on first-principle calculations, we also predicted their giant out-of-plane optical anisotropy for monocrystals. As a practical illustration of the obtained optical properties, we demonstrated surface plasmon resonance biosensors with PtS2 or PtSe2 functional layers, which dramatically improves sensor sensitivity by 60 and 30%, respectively.

scholarly journals Active Electromagnetically Induced Transparency Effect in Graphene-Dielectric Hybrid Metamaterial and Its High-Performance Sensor Application

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2032
Author(s):  
Fan Gao ◽  
Peicheng Yuan ◽  
Shaojun Gao ◽  
Juan Deng ◽  
Zhiyu Sun ◽  
...  
Keyword(s):  
Refractive Index ◽  
Near Infrared ◽  
Slow Light ◽  
Electromagnetically Induced Transparency ◽  
High Refractive Index ◽  
Infrared Region ◽  
Refractive Index Sensitivity ◽  
Index Sensitivity ◽  
Induced Transparency ◽  
Hybrid Metamaterial

Electromagnetically induced transparency (EIT) based on dielectric metamaterials has attracted attentions in recent years because of its functional manipulation of electromagnetic waves and high refractive index sensitivity, such as high transmission, sharp phase change, and large group delay, etc. In this paper, an active controlled EIT effect based on a graphene-dielectric hybrid metamaterial is proposed in the near infrared region. By changing the Fermi level of the top-covered graphene, a dynamic EIT effect with a high quality factor (Q-factor) is realized, which exhibits a tunable, slow, light performance with a maximum group index of 2500. Another intriguing characteristic of the EIT effect is its high refractive index sensitivity. In the graphene-covered metamaterial, the refractive index sensitivity is simulated as high as 411 nm/RIU and the figure-of-merit (FOM) is up to 159, which outperforms the metastructure without graphene. Therefore, the proposed graphene-covered dielectric metamaterial presents an active EIT effect in the near infrared region, which highlights its great application potential in deep optical switching, tunable slow light devices, and sensitive refractive index sensors, etc.

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