Field canalization using anisotropic 2D plasmonics

AbstractOptical devices capable of suppressing diffraction nature of light are of great technological importance to many nanophotonic applications. One important technique to achieve diffractionless optics is to exploit field canalization effect. However, current technological platforms based on metamaterial structures typically suffer from strict loss-confinement trade-off, or lack dynamic reconfigurability over device operations. Here we report an integrated canalization platform that can alleviate this performance trade-off. It is found that by leveraging material absorption of anisotropic 2D materials, the dispersion of this class of materials can flatten without increasing propagation losses and compromising confinement. The realization of such plasmon canalization can be considered using black phosphorus (BP), where topological transition from elliptic to hyperbolic curves can be induced by dynamically leveraging material absorption of BP. At the transition point, BP film can support long range, deeply subwavelength, near-diffractionless field propagation, exhibiting diffraction angle of 5.5°, propagation distance of 10λspp, and λspp < λ0/300.

Download Full-text

Thermally-Induced Dehydrogenative Coupling of Organosilanes and H-Terminated Silicon Quantum Dots onto Germanane Surfaces

10.26434/chemrxiv.11794404 ◽

2020 ◽

Author(s):

Haoyang Yu ◽

Alyxandra Thiessen ◽

Md Asjad Hossain ◽

Marc Julian Kloberg ◽

Bernhard Rieger ◽

...

Keyword(s):

2D Materials ◽

Future Generation ◽

Optical Devices ◽

Surface Reactivity ◽

Organic Monolayers ◽

Present Contribution ◽

Thermally Induced ◽

Dehydrogenative Coupling ◽

Silicon Quantum Dot ◽

Covalently Bonded

<div><div><div><p>Covalently bonded organic monolayers play important roles in defining the solution processability, ambient stability, and electronic properties of two-dimensional (2D) materials such as Ge nanosheets (GeNSs); they also hold promise of providing avenues for the fabrication of future generation electronic and optical devices. Functionalization of GeNS normally involves surface moieties linked through covalent Ge−C bonds. In the present contribution we extend the scope of surface linkages to include Si−Ge bonding and present the first demonstration of heteronuclear dehydrocoupling of organosilanes to hydride-terminated GeNSs obtained from the deintercalation and exfoliation of CaGe2. We further exploit this new surface reactivity and demonstrated the preparation of directly bonded silicon quantum dot-Ge nanosheet hybrids.</p></div></div></div>

Download Full-text

All-Optical Modulation Technology Based on 2D Layered Materials

Micromachines ◽

10.3390/mi13010092 ◽

2022 ◽

Vol 13 (1) ◽

pp. 92

Author(s):

Hongyan Yang ◽

Yunzheng Wang ◽

Zian Cheak Tiu ◽

Sin Jin Tan ◽

Libo Yuan ◽

...

Keyword(s):

Optical Properties ◽

Communication Systems ◽

Near Infrared ◽

2D Materials ◽

Optical Devices ◽

Optical Systems ◽

Optical Modulation ◽

Wavelength Converter ◽

Optical Modulators ◽

All Optical

In the advancement of photonics technologies, all-optical systems are highly demanded in ultrafast photonics, signal processing, optical sensing and optical communication systems. All-optical devices are the core elements to realize the next generation of photonics integration system and optical interconnection. Thus, the exploration of new optoelectronics materials that exhibit different optical properties is a highlighted research direction. The emerging two-dimensional (2D) materials such as graphene, black phosphorus (BP), transition metal dichalcogenides (TMDs) and MXene have proved great potential in the evolution of photonics technologies. The optical properties of 2D materials comprising the energy bandgap, third-order nonlinearity, nonlinear absorption and thermo-optics coefficient can be tailored for different optical applications. Over the past decade, the explorations of 2D materials in photonics applications have extended to all-optical modulators, all-optical switches, an all-optical wavelength converter, covering the visible, near-infrared and Terahertz wavelength range. Herein, we review different types of 2D materials, their fabrication processes and optical properties. In addition, we also summarize the recent advances of all-optical modulation based on 2D materials. Finally, we conclude on the perspectives on and challenges of the future development of the 2D material-based all-optical devices.

Download Full-text

2D materials towards ultrafast photonic applications

Physical Chemistry Chemical Physics ◽

10.1039/d0cp02841j ◽

2020 ◽

Vol 22 (39) ◽

pp. 22140-22156

Author(s):

Xin-Ping Zhai ◽

Bo Ma ◽

Qiang Wang ◽

Hao-Li Zhang

Keyword(s):

Optical Communications ◽

2D Materials ◽

Optical Limiting ◽

Mode Locking ◽

Optical Devices ◽

Optical Modulation ◽

Two Dimensional ◽

Two Dimensional Materials ◽

All Optical ◽

Ultrafast Photonics

Two-dimensional materials are now excelling in yet another arena of ultrafast photonics, including optical modulation through optical limiting/mode-locking, photodetectors, optical communications, integrated miniaturized all-optical devices, etc.

Download Full-text

Monte Carlo Study of Electronic Transport in Monolayer InSe

Materials ◽

10.3390/ma12244210 ◽

2019 ◽

Vol 12 (24) ◽

pp. 4210 ◽

Cited By ~ 6

Author(s):

Sanjay Gopalan ◽

Gautam Gaddemane ◽

Maarten L. Van de Put ◽

Massimo V. Fischetti

Keyword(s):

Monte Carlo ◽

Long Range ◽

Electron Mobility ◽

Short Range ◽

Field Effect Transistors ◽

2D Materials ◽

Matrix Elements ◽

Electronic Band ◽

Low Field ◽

Wide Range

The absence of a band gap in graphene makes it of minor interest for field-effect transistors. Layered metal chalcogenides have shown great potential in device applications thanks to their wide bandgap and high carrier mobility. Interestingly, in the ever-growing library of two-dimensional (2D) materials, monolayer InSe appears as one of the new promising candidates, although still in the initial stage of theoretical studies. Here, we present a theoretical study of this material using density functional theory (DFT) to determine the electronic band structure as well as the phonon spectrum and electron-phonon matrix elements. The electron-phonon scattering rates are obtained using Fermi’s Golden Rule and are used in a full-band Monte Carlo computer program to solve the Boltzmann transport equation (BTE) to evaluate the intrinsic low-field mobility and velocity-field characteristic. The electron-phonon matrix elements, accounting for both long- and short-range interactions, are considered to study the contributions of different scattering mechanisms. Since monolayer InSe is a polar piezoelectric material, scattering with optical phonons is dominated by the long-range interaction with longitudinal optical (LO) phonons while scattering with acoustic phonons is dominated by piezoelectric scattering with the longitudinal (LA) branch at room temperature (T = 300 K) due to a lack of a center of inversion symmetry in monolayer InSe. The low-field electron mobility, calculated considering all electron-phonon interactions, is found to be 110 cm2V−1s−1, whereas values of 188 cm2V−1s−1 and 365 cm2V−1s−1 are obtained considering the long-range and short-range interactions separately. Therefore, the calculated electron mobility of monolayer InSe seems to be competitive with other previously studied 2D materials and the piezoelectric properties of monolayer InSe make it a suitable material for a wide range of applications in next generation nanoelectronics.

Download Full-text

Multifield-tunable magneto-optical effects in electron- and hole-doped nitrogen–graphene crystals

Journal of Materials Chemistry C ◽

10.1039/c9tc00315k ◽

2019 ◽

Vol 7 (11) ◽

pp. 3360-3368 ◽

Cited By ~ 2

Author(s):

Xiaodong Zhou ◽

Fei Li ◽

Yanxia Xing ◽

Wanxiang Feng

Keyword(s):

2D Materials ◽

Optical Devices ◽

Strain Fields ◽

2D Material ◽

Optical Effects ◽

Faraday Effects

The magneto-optical effects play a prominent role in probing the exotic magnetism in 2D materials. Here, we present that the magneto-optical Kerr and Faraday effects in carrier-doped nitrogen–graphene crystals can be effectively mediated by electric, magnetic, and strain fields. Our results indicate that nitrogen–graphene crystals provide a novel 2D material platform for nano-spintronics and magneto-optical devices.

Download Full-text

How the flow and processing of information shapes the cerebrum

10.7287/peerj.preprints.239v2 ◽

2015 ◽

Author(s):

Marc H.E. de Lussanet

Keyword(s):

White Matter ◽

Long Range ◽

Information Flow ◽

Information Transfer ◽

Regular Structure ◽

Cortical Surface ◽

Local Networks ◽

Trade Off ◽

Processing Power ◽

Underlying Mechanisms

The cerebrum of mammals spans a vast range of sizes and yet has a very regular structure. The amount of folding of the cortical surface and the proportion of white matter gradually increase with size, but the underlying mechanisms remain elusive. Here, two laws are derived to fully explain these cerebral scaling relations. The two general laws are derived from the notion that total processing power of the cortex is determined by the total cortical surface (i.e., the number of neurons), whereas the most efficient over-all flow of information is governed by the size of local networks (cortical columns). Since information is transferred by axonal connections which have a definite volume, a trade-off can be formulated from theoretical considerations between local, inter-gyral information transfer and long-range information transfer. It can be shown that this trade-off is governed by a single parameter describing the size of local networks, tlocal. Despite having just one free parameter, the first law fits the mammalian cerebrum better than any existing function, both across species and within humans. According to the second law, the scaling of white matter volume is also determined by the information principles. It follows that large cerebrums have much local processing and little global information flow. Moreover, paradoxically, a further increase in long-range connections would decrease the efficiency of information flow. These theoretical scaling principles help to compare the cerebrums across mammals regardless their size.

Download Full-text