scholarly journals Synthesis of High-Performance Photonic Crystal Film for SERS Applications via Drop-Coating Method

Coatings ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 679
Author(s):  
Ming-Xue Wei ◽  
Chao-Hui Liu ◽  
Han Lee ◽  
Bo-Wei Lee ◽  
Chun-Han Hsu ◽  
...  
Keyword(s):  
Particle Size ◽  
Photonic Crystal ◽  
Band Gap ◽  
Colloidal Particles ◽  
Laser Source ◽  
Synthesis Process ◽  
Large Area ◽  
Structural Colors ◽  
Crystal Film ◽  
Coating Method

Silica nanospheres with a well-controlled particle size were prepared via a nucleation-to-growth synthesis process. A facile method is proposed for improving the self-assembly behavior of silica colloidal particles in droplet coatings by the simple controlling of the drying temperature. It is shown that a periodically arranged, opal-structured, photonic crystal film with a large area of approximately 4.0 cm2 can be prepared, even when the particle size is up to 840 nm. When the band gap of the silica photonic crystals falls in the visible-light region, the crystals exhibit distinct structural colors. Moreover, the wavelength of the reflected light increases with an increasing particle size of silica. When the photonic band gap overlaps the wavelength of the laser source, the overall Raman spectrum intensity is significantly enhanced. Accordingly, the proposed nucleation-to-growth process and drop-coating method provides a cheap and simple approach for the manufacture of uniform sized silica and surface-enhanced Raman scattering substrates, respectively.

scholarly journals Large-area flexible colloidal photonic crystal film stickers for light trapping applications

2018 ◽  
Vol 8 (4) ◽  
pp. 960 ◽  
Author(s):  
Tomas Kohoutek ◽  
Mikhail Parchine ◽  
Maria Bardosova ◽  
Hiroshi Fudouzi ◽  
Martyn Pemble
Keyword(s):  
Photonic Crystal ◽  
Light Trapping ◽  
Large Area ◽  
Crystal Film

Effect of synthesis process on particle size and band gap of Er3+ doped Y2Sio5

2019 ◽  
Author(s):  
Kanchan Upadhyay ◽  
Sabu Thomas ◽  
Nandakumar Kalarikkal ◽  
Raunak Kumar Tamrakar
Keyword(s):  
Particle Size ◽  
Band Gap ◽  
Synthesis Process

Synthesis and Characterization of PVA/TiO2 Nanocomposite

2017 ◽  
Vol 737 ◽  
pp. 242-247
Author(s):  
R.K. Duchaniya ◽  
Niresh Choudhary
Keyword(s):  
Thin Film ◽  
Titanium Dioxide ◽  
Polyvinyl Alcohol ◽  
Band Gap ◽  
Titanium Dioxide Nanoparticles ◽  
Group Analysis ◽  
Synthesis Process ◽  
Electronic Band ◽  
Vis Spectroscopy ◽  
Coating Method

A thin film of polyvinyl alcohol (PVA) and nanocomposite of PVA/TiO2 have been prepared by spin coating method at room temperature. The influence of titanium dioxide nanoparticles on the structure, optical, and functional group analysis of nanocomposite of polyvinyl alcohol/titanium dioxide was studied by using X-ray diffraction analysis, UV–vis spectroscopy and FTIR (Fourier Transform Infrared Spectroscopy). As some significant amount of titanium dioxide nanoparticles were added to the synthesis process of a thin film of PVA/TiO2 nanocomposite and it was found that electronic band gap of the polyvinyl alcohol decreases from 3.94 eV to 3.04 eV, and absorption wavelength shifted towards red. For titanium dioxide nanoparticles, the calculated value of band gap is 3.24 eV. The XRD peak of the PVA/TiO2 was obtained in between the peak of the titanium dioxide nanoparticles and polyvinyl alcohol. FTIR confirms the presence of bonds Ti-O, -OH , -CH2 , -CH3 and of a carbonyl group.

scholarly journals Mastering of NIL Stamps with Undercut T-Shaped Features from Single Layer to Multilayer Stamps

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 956
Author(s):  
Philipp Taus ◽  
Adrian Prinz ◽  
Heinz D. Wanzenboeck ◽  
Patrick Schuller ◽  
Anton Tsenov ◽  
...  
Keyword(s):  
Electron Beam Lithography ◽  
Nanoimprint Lithography ◽  
Silicon Oxide ◽  
Three Dimensional ◽  
Single Layer ◽  
Fabrication Technology ◽  
Large Area ◽  
Structural Colors ◽  
Biomimetic Structures ◽  
Morpho Butterfly

Biomimetic structures such as structural colors demand a fabrication technology of complex three-dimensional nanostructures on large areas. Nanoimprint lithography (NIL) is capable of large area replication of three-dimensional structures, but the master stamp fabrication is often a bottleneck. We have demonstrated different approaches allowing for the generation of sophisticated undercut T-shaped masters for NIL replication. With a layer-stack of phase transition material (PTM) on poly-Si, we have demonstrated the successful fabrication of a single layer undercut T-shaped structure. With a multilayer-stack of silicon oxide on silicon, we have shown the successful fabrication of a multilayer undercut T-shaped structures. For patterning optical lithography, electron beam lithography and nanoimprint lithography have been compared and have yielded structures from 10 µm down to 300 nm. The multilayer undercut T-shaped structures closely resemble the geometry of the surface of a Morpho butterfly, and may be used in future to replicate structural colors on artificial surfaces.

scholarly journals Band-Gap Solitons in Nonlinear Photonic Crystal Waveguides and Their Application for Functional All-Optical Logic Gating

Photonics ◽  
2021 ◽  
Vol 8 (7) ◽  
pp. 250
Author(s):  
Vakhtang Jandieri ◽  
Ramaz Khomeriki ◽  
Tornike Onoprishvili ◽  
Daniel Erni ◽  
Levan Chotorlishvili ◽  
...  
Keyword(s):  
Photonic Crystal ◽  
Band Gap ◽  
Crystalline Silicon ◽  
Logic Gates ◽  
Photonic Crystal Waveguides ◽  
Optical Logic ◽  
Logical Operation ◽  
Pulse Envelope ◽  
Gap Soliton ◽  
All Optical

This review paper summarizes our previous findings regarding propagation characteristics of band-gap temporal solitons in photonic crystal waveguides with Kerr-type nonlinearity and a realization of functional and easily scalable all-optical NOT, AND and NAND logic gates. The proposed structure consists of a planar air-hole type photonic crystal in crystalline silicon as the nonlinear background material. A main advantage of proposing the gap-soliton as a signal carrier is that, by operating in the true time-domain, the temporal soliton maintains a stable pulse envelope during each logical operation. Hence, multiple concatenated all-optical logic gates can be easily realized paving the way to multiple-input ultrafast full-optical digital signal processing. In the suggested setup, due to the gap-soliton features, there is no need to amplify the output signal after each operation which can be directly used as a new input signal for another logical operation. The efficiency of the proposed logic gates as well as their scalability is validated using our original rigorous theoretical formalism confirmed by full-wave computational electromagnetics.

scholarly journals Characteristic Analysis and Structural Design of Hollow-Core Photonic Crystal Fibers with Band Gap Cladding Structures

Sensors ◽  
2021 ◽  
Vol 21 (1) ◽  
pp. 284
Author(s):  
Bowei Wan ◽  
Lianqing Zhu ◽  
Xin Ma ◽  
Tianshu Li ◽  
Jian Zhang
Keyword(s):  
Photonic Crystal ◽  
Band Gap ◽  
Photonic Crystal Fibers ◽  
Relative Sensitivity ◽  
Confinement Loss ◽  
Hollow Core ◽  
Characteristic Analysis ◽  
Element Analysis ◽  
The Core ◽  
Crystal Fibers

Due to their flexible structure and excellent optical characteristics hollow-core photonic crystal fibers (HC-PCFs) are used in many fields, such as active optical devices, communications, and optical fiber sensing. In this paper, to analyze the characteristics of HC-PCFs, we carried out finite element analysis and analyzed the design for the band gap cladding structure of HC-PCFs. First, the characteristics of HC19-1550 and HC-1550-02 in the C-band were simulated. Subsequently, the structural optimization of the seven-cell HC-1550-02 and variations in characteristics of the optimized HC-1550-02 in the wavelength range 1250–1850 nm were investigated. The simulation results revealed that the optimal number of cladding layers is eight, the optimal core radius is 1.8 times the spacing of adjacent air holes, and the optimal-relative thickness of the core quartz-ring is 2.0. In addition, the low confinement loss bandwidth of the optimized structure is 225 nm. Under the transmission bandwidth of the optimized structure, the core optical power is above 98%, the confinement loss is below 9.0 × 10−3 dB/m, the variation range of the effective mode field area does not exceed 10 μm2, and the relative sensitivity is above 0.9570. The designed sensor exhibits an ultra-high relative sensitivity and almost zero confinement loss, making it highly suitable for high-sensitivity gas or liquid sensing.

Stability of a Binary Colloidal Suspension and its effect on Colloidal Processing

1989 ◽  
Vol 155 ◽  
Author(s):  
Wan V. Shih ◽  
Wei-Heng Shih ◽  
Jun Liu ◽  
Ilhan A. Aksay
Keyword(s):  
Particle Size ◽  
Hard Sphere ◽  
Colloidal Particles ◽  
Colloidal Suspension ◽  
Fluid Phase ◽  
Ceramic Processing ◽  
Colloidal Processing ◽  
Interparticle Interactions ◽  
The Stability ◽  
Binary Suspension

The stability of a colloidal suspension plays an important role in colloidal processing of materials. The stability of the colloidal fluid phase is especially vital in achieving high green densities. By colloidal fluid phase, we refer to a phase in which colloidal particles are well separated and free to move about by Brownian motion, By controlling parameters such as pH, salt concentration, and surfactants, one can achieve high packing (green) densities in the repulsive regime where the suspension is well dispersed as a colloidal fluid, and low green densities in the attractive regime where the suspensions are flocculated [1,2]. While there is increasing interest in using bimodal suspensions to improve green densities, neither the stability of a binary suspension as a colloidal fluid nor the stability effects on the green densities have been studied in depth as yet. Traditionally, the effect of using bimodal-particle-size distribution has only been considered in terms of geometrical packing developed by Furnas and others [3,4]. This model is a simple packing concept and is used and useful for hard sphere-like repulsive interparticle interactions. With the advances in powder technology, smaller and smaller particles are available for ceramic processing. Thus, the traditional consideration of geometrial packing for the green densities of bimodal suspensions may not be enough. The interaction between particles must be taken into account.

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