Light strongly interacts with structures that are of a similar scale to its wavelength; typically nanoscale features for light in the visible spectrum. However, optical response these nanostructures is usually fixed during fabrication. Phase change materials offer way tune properties nanoseconds. Until now, phase active photonics use absorb light, which limits their application In contrast, Stibnite (Sb2S3) an under-explored material band gap can be tuned spectrum from 2.0 1.7 eV. We...

The effect of oxygen on the local structure Ge atoms in GeTe-O materials has been investigated. Oxygen leads to a significant modification vibrational modes octahedra, which results from decrease its coordination. We find that defective octahedral network is crucial fingerprint for rapid and reversible structural transitions GeTe-based phase change materials. appearance oxide Raman confirms separation into GeO TeO at high level O doping. Counterintuitively, despite increase crystallization...

Abstract Tunable and reconfigurable functionalities are crucial for advanced photonic devices. In this study, CSb 2 Te 3 is proposed as a new optical tuning material. Single‐shot picosecond laser pulses used to transform the into six different states; each state can be achieved from any other state. The dielectric function unique switching on time scale. impact of crystal structure mechanism studied using transmission electron microscopy density functional theory. Second harmonic generation...

The objective of this work is to design and demonstrate multilevel optical switches by combining different phase change materials. Ge2Sb2Te5 VO2 nanolayer structures were designed maximize the contrast between four reflective states. These states arise due independent structural transitions at temperatures. transfer matrix method was used model Fresnel reflection for each combination then optimize layer thicknesses, which found be 70 nm 50 nm. switching results provide further possibilities...

By confining phase transitions to the nanoscale interface between two different crystals, interfacial change memory heterostructures represent state of art for energy efficient data storage. We present effect strain engineering on electrical switching performance –GeTe superlattice van der Waals devices. Multiple Ge atoms through a two-dimensional Te layer reduces activation barrier further switch; an that can be enhanced by biaxial strain. The out-of-plane phonon mode GeTe crystal remains...

The objective of this paper is to review the characterisation methods and procedures used laser switch phase change materials, then assess their applicability for characterising materials active photonics devices. Specifically we characterise performance our pump-probe system compare it with other ‘static’ ‘dynamic’ testers. Our was developed measure transformation kinetics chalcogenide films by simultaneously measuring transmission reflection a probe temporal resolution 1 ns. We also use...

Chalcogenides are materials that substantially consist of sulphur, selenium, and tellurium. Their dielectric properties can be tuned by thermally induced structural phase transitions, photostructural dissolution metal dopants. We have designed active photonic structures using a range `tuneable' chalcogenides. The resonant frequency plasmonic was over 100 nm band in the visible, metal-chalcogenidemetal provide tuning 0.5 μm mid-infrared, hyperbolic metamaterials incorporating chalcogenides...

Metamaterial (MM) perfect absorbers are realised over various spectra from visible to microwave. Recently, different approaches have been explored integrate tunability into MM absorbers. Particularly, tuning has illustrated through electrical-, thermal-, and photo-induced changes the permittivity of active medium within However, intricate design, expensive nanofabrication process, volatile nature limit widespread applications Metal-dielectric stack layered hyperbolic metamaterials (HMMs)...

We use an evolutionary algorithm to explore the design space of hexagonal Ge2Sb2Te5; a van der Waals layered two dimensional crystal heterostructure. The Ge2Sb2Te5 structure is more complicated than previously thought. Predominant features include layers Ge3Sb2Te6 and Ge1Sb2Te4 crystals that interact through Te–Te bonds. Interestingly, (Ge/Sb)–Te–(Ge/Sb)–Te alternation common feature for most stable structures each generation's evolution. This emergent rule provides important structural...

The objective of this work is to demonstrate the usefulness fractional factorial design for optimizing crystal quality chalcogenide van der Waals (vdW) crystals. We statistically analyze growth parameters highly c axis oriented Sb2Te3 crystals and Sb2Te3–GeTe phase change vdW heterostructured superlattices. statistical significance temperature, pressure, power, buffer materials, layer thickness was found by response surface analysis. Temperature, their second-order interactions are major...

Methoxsalen has been used for the treatment of psoriasis. In order to develop alternative formulations topical administration methoxsalen, chitosan coated microemulsion were evaluated as delivery vehicle. Microemulsions prepared using water, soyabean oil. Egg phosphatidylcholine, ethanol and with chitosan. They characterized shape surface morphology, droplet size distribution, zeta potential, pH viscosity. The ability system deliver into skin was dialysis membrane human cadaver skin. in...

Experimental studies in design are often done using novice engineers such as students test subjects. In this paper, we attempt to determine differences cognition skills between expert and engineers, order the utility validity of experimental subjects science research. A classification is developed based on a literature review. It found that cognitive strategies, processes representations noticeably dissimilar experts novices. Given these observations, data collected student samples can only...

To date, the second harmonic generation (SHG) has a great effect on photonic devices. However, it is formidable challenge to achieve reconfigurable SHG. Hereby, we experimentally demonstrate SHG response from oriented Ge2Sb2Te5 (GST) grains induced by polarized laser pulses for first time. The orientation of GST found be perpendicular polarization direction pump laser. Such unique ordered structures result in periodic change intensity with input angle rotating every 180°. These findings may...

Perfect absorption ranging from visible, infrared, terahertz, to microwave is desirable for solar cell, photodetection, telecommunications, and molecular sensing. Recently, the air/dielectric–metal stacks/substrate‐based asymmetric Fabry–Pérot (FP) cavity has attracted much attention owing lithography‐free design which scalable low cost. Herein, a reversibly tunable FP high absorber in near‐infrared (NIR) region experimentally demonstrated, relying on chalcogenide (Ge 2 Sb Te 5 )–metal (Au)...

Abstract The amorphous to crystalline phase transition in Ge 2 Sb Te 5 (GST) change material is investigated using XRD and the systematic variation optical band-gap ( E g ) structural disorder B 1/2 employing UV-Vis-NIR spectroscopy. observed have value of 0.708 eV while (200 °C) shows 0.442 eV. Variation slope 13.4 % noted around crystallization temperature (150 °C), depicting reduction hence ordering forming cubic phase. local upon occurs due alternation atomic bonding configurations,...

Abstract We propose a wide-angle metamaterial absorber with more than 90% absorption in the far-infrared (F-IR) and terahertz (THz) regimes. Our metal-dielectric consists of phase change layer (Ge 2 Sb Te 5 ), dielectric spacer (MgF bottom refractory metal (TiN). numerically designed structure by finite-difference time-domain simulation method demonstrated perfect spectral range from 10 μ m to 50 (30 THz 6 THz). Furthermore, it shows broad peak maximum 93% at resonant wavelength 22.5 when is...

In this paper, we introduce a class of unitary operators defined on the Bergman space $L_a^2(\mathbb{C}_+)$ right half plane $\mathbb{C}_+$ and study certain algebraic properties these operators. Using results, then show that bounded linear operator $S$ from into itself commutes with all weighted composition $W_a, \in \mathbb{D}$ if only $\widetilde{S}(w)=\langle Sb_{\overline{w}},b_{\overline{w}}\rangle, w \mathbb{C}_+ $ satisfies averaging condition. Here for $a=c+id \mathbb{D}, f...

The ability to design and tune the local crystal structure of chalcogenide materials with R3̅m space group in superlattices allows performance properties interfacial phase-change memory be engineered. Designing superlattice high in-plane biaxial strain provides a further path decrease switching energy devices. Here, we report how hexagonal lattice constants concomitant phonon modes Sb2Te3–Bi2Te3, Sb2Te3–Bi2Se3, Bi2Te3–Bi2Se3 can controlled c-axis-oriented texture. Highly oriented iPCM...