scholarly journals High Refractive Index Inverse Vulcanized Polymers for Organic Photonic Crystals

Crystals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 154 ◽  
Author(s):  
Christian Tavella ◽  
Paola Lova ◽  
Martina Marsotto ◽  
Giorgio Luciano ◽  
Maddalena Patrini ◽  
...  
Keyword(s):  
Refractive Index ◽  
Photonic Crystals ◽  
Photonic Band Gap ◽  
High Refractive Index ◽  
Melt Processing ◽  
Added Value ◽  
New Approach ◽  
Dielectric Contrast ◽  
High Dielectric ◽  
Photonic Band

Photonic technologies are nowadays dominated by highly performing inorganic structures that are commonly fabricated via lithography or epitaxial growths. Unfortunately, the fabrication of these systems is costly, time consuming, and does not allow for the growth of large photonic structures. All-polymer photonic crystals could overcome this limitation thanks to easy solubility and melt processing. On the other hand, macromolecules often do not offer a dielectric contrast large enough to approach the performances of their inorganic counterparts. In this work, we demonstrate a new approach to achieve high dielectric contrast distributed Bragg reflectors with a photonic band gap that is tunable in a very broad spectral region. A highly transparent medium was developed through a blend of a commercial polymer with a high refractive index inverse vulcanized polymer that is rich in sulfur, where the large polarizability of the S–S bond provides refractive index values that are unconceivable with common non-conjugated polymers. This approach paves the way to the recycling of sulfur byproducts for new high added-value nano-structures.

3-Dimensional Photonic Crystals at Optical Wavelengths

1998 ◽  
Vol 07 (02) ◽  
pp. 181-200 ◽  
Author(s):  
S. G. Romanov
Keyword(s):  
Photonic Crystals ◽  
Band Gap ◽  
Photonic Band Gap ◽  
Stop Band ◽  
High Refractive Index ◽  
3 Dimensional ◽  
Optical Wavelength ◽  
Photonic Band Gap Materials ◽  
Optical Wavelengths ◽  
Photonic Band

Different experimental strategies towards the 3-dimensional photonic crystals operating at optical wavelength are classified. The detailed discussion is devoted to the recent progress in photonic crystals fabricated by template method — the photonic band gap materials on the base of opal. The control of photonic properties of opal-based gratings is achieved through impregnating the opal with high refractive index semiconductors and dielectrics. Experimental study demonstrated the dependence of the stop band behaviour upon the type of impregnation (complete or partial) and showed a way for approaching complete photonic band gap. The photoluminescence from opal- semiconductor gratings revealed suppression of spontaneous emission in the gap region with following enhancement of the emission efficiency at the low-energy edge of the gap.

scholarly journals Titania Photonic Crystals with Precise Photonic Band Gap Position via Anodizing with Voltage versus Optical Path Length Modulation

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 651 ◽  
Author(s):  
Ermolaev ◽  
Kushnir ◽  
Sapoletova ◽  
Napolskii
Keyword(s):  
Refractive Index ◽  
Photonic Crystals ◽  
Band Gap ◽  
Titanium Oxide ◽  
Effective Refractive Index ◽  
Photonic Band Gap ◽  
Voltage Versus ◽  
Research Attention ◽  
Anodic Titanium Oxide ◽  
Photonic Band

Photonic crystals based on titanium oxide are promising for optoelectronic applications, for example as components of solar cells and photodetectors. These materials attract great research attention because of the high refractive index of TiO2. One of the promising routes to prepare photonic crystals based on titanium oxide is titanium anodizing at periodically changing voltage or current. However, precise control of the photonic band gap position in anodic titania films is a challenge. To solve this problem, systematic data on the effective refractive index of the porous anodic titanium oxide are required. In this research, we determine quantitatively the dependence of the effective refractive index of porous anodic titanium oxide on the anodizing regime and develop a model which allows one to predict and, therefore, control photonic band gap position in the visible spectrum range with an accuracy better than 98.5%. The prospects of anodic titania photonic crystals implementation as refractive index sensors are demonstrated.

Fabrication of two-dimensional photonic structure of titanium dioxide with sub-micrometer resolution by deep x-ray lithography

2004 ◽  
Vol 820 ◽  
Author(s):  
Koichi Awazu ◽  
Makoto Fujimaki ◽  
Xiaomin Wang ◽  
Akihide Sai ◽  
Yoshimichi Ohki
Keyword(s):  
Refractive Index ◽  
Titanium Dioxide ◽  
Photonic Crystals ◽  
Band Gap ◽  
Photonic Band Gap ◽  
3D Structure ◽  
Two Dimensional ◽  
Nano Structure ◽  
X Ray ◽  
Photonic Band

AbstractTwo dimensional photonic crystals of titanium dioxide is expected to have many advantage compared with photonic crystals of semiconductors, e.g., silicon and GaAs. For example, low optical loss in the near infrared region used for optical communication, low thermal expansion, and its refractive index which is close to that for optical fiber are attractive advantages. However, it is difficult to create micro-nano structure in titanium dioxide because micro-fabrication technique for semiconductor is not available for titanium dioxide. As the first step we calculated photonic band gap of titanium dioxide rod-slab on SiO2. Also, band gap percent against thickness of the rod-slab was examined. Finally, we confirmed the most suitable structure of 2D photonic crystals. Deep x-ray lithography technique was employed for create a very deep and precise template of PMMA. Then, liquid-phase deposition was used to faithfully deposit a tightly packed layer of titanium oxide onto the template. Finally, the template is selectively removed to obtain a photonic nano-structure. We also calculate photonic band gap on the 3D-structure of TiO2. A template for the most appropriate structure was fabricated by the method proposed by Yablonovitch. By using of the same method, it was successful to obtain 3D structure of TiO2. Refractive index of obtained TiO2 followed by heating at 700°C was determined to 2.5 which is close to that for anatase phase.

Fabrication of Flexible One-Dimensional Porous Silicon Photonic Band-Gap Structures

2003 ◽  
Vol 797 ◽  
Author(s):  
Natalya Tokranova ◽  
Bai Xu ◽  
James Castracane
Keyword(s):  
Refractive Index ◽  
Porous Silicon ◽  
Photonic Crystals ◽  
Band Gap ◽  
Dielectric Material ◽  
Photonic Band Gap ◽  
Bragg Reflector ◽  
One Dimensional ◽  
Fabry Perot ◽  
Photonic Band

Photonic crystals are periodic dielectric structures that have a photonic band gap to control the propagation of light in a certain wavelength range. This property offers a means to manipulate photons in the same way as electrons can be controlled in an atomic lattice. Porous silicon is an ideal candidate fo r the fabrication of photonic crystals because of the availability of a variety of silicon micromachining techniques. One-dimensional photonic crystals with customized parameters can be economically fabricated using porous silicon multilayer structures with periodically modulated porosity. Despite the structural non-homogeneities, porous silicon fabricated on a p-type Si substrate has optical properties similar to a dielectric material with a single effective refractive index. The exact value of the refractive index for each layer depends on its porosity. An engineered porosity can be obtained by changing the etching currents during the anodization process. This results in a modulation of the refractive index. A stack of alternating layers with high and low porosity produces a distributed Bragg reflector (DBR). Various designs incorporating multilayer porous silicon structures with an optical Fabry-Perot resonator and coupled microcavities are under development and can serve as an optical filter. Prototypes of such free-standing structures with 21–200 stacked layers to be used as DBRs, Fabry-Perot resonators or coupled microcavities are being fabricated. These structures are coated with polystyrenesulfonate on their backsides to increase mechanical strength and at the same time maintain flexibility. In this work, reflectance spectra of these porous silicon multilayers with and without polymer on the backside were measured. Simulations of the multilayer one-dimensional photonic crystals were performed to predic t the reflectance spectrum and optimize their structures before the fabrication and to compare to experimental data.

scholarly journals Design and Analysis of a Photonic Crystal Based Biosensor Working at THz Frequency Region

2015 ◽  
Vol 62 (1) ◽  
pp. 7-9 ◽  
Author(s):  
Bratati Ghosh ◽  
Shukufe Rahman ◽  
Ahsan Habib ◽  
Subrata Das
Keyword(s):  
Refractive Index ◽  
Photonic Crystal ◽  
Photonic Crystals ◽  
Band Gap ◽  
Photonic Band Gap ◽  
Frequency Region ◽  
Maximum Sensitivity ◽  
The Relationship ◽  
Photonic Band

2D Photonic Crystal is investigated to find photonic band gap for the purpose of biosensing at THz frequency region. Several structures, one consisting of air holes in Si background and the others consisting of air holes filled with different analytes of having different Refractive Index (RI) in same Si background are considered. For each structure the change in photonic band gap due to the change in RI is observed and shown graphically. By comparing this plot with a standard chart of RI of different materials, any unknown biological analyte can be identified. Thus a biosensing method is developed by using the relationship between RI and band gap of photonic crystals. By comparing and calculating from the relationship; the maximum sensitivity of the developed biosensor is found to be 66.6%. DOI: http://dx.doi.org/10.3329/dujs.v62i1.21952 Dhaka Univ. J. Sci. 62(1): 7-9, 2014 (January)

scholarly journals MODELING OF MULTILAYER ULTRATHIN-FILM PHOTONIC CRYSTALS FOR SELECTIVE FILTERS

Doklady BGUIR ◽  
2019 ◽  
pp. 88-94
Author(s):  
L. S. Khoroshko ◽  
A. V. Baglov ◽  
A. A. Hnitsko
Keyword(s):  
Crystal Structure ◽  
Refractive Index ◽  
Liquid Crystal ◽  
Photonic Crystal ◽  
Photonic Crystals ◽  
Band Gap ◽  
Photonic Band Gap ◽  
Layer Structure ◽  
Half Wave ◽  
Photonic Band

The aim of the work was to study the optical properties of the one-dimensional photonic crystals from ultrathin alternating layers of titanium and silicon oxides with different order of alternating layers to form defective half-wave layers in the bulk of the photonic crystal. The layer thicknesses were optimized by the dispersion of the refractive index and it was shown that for the formation of 16-layer photonic crystal structure without a half-wave layer with a photonic band gap in the UV region, it is necessary to use layers of titanium dioxide and silicon oxide with a thickness of 28.3 and 53.2 nm, respectively. The structure of the 26-layer photonic crystal with a thickness of 2130 nm with two non-equidistant half-wave layers forming resonant transmission bands in the photonic band gap with peaks at 550 and 601 nm is proposed. Due to the dispersion of the refractive index, the ratio of the thicknesses of TiO2:SiO2 layers varies from 1:1.88 in the case of a 16-layer structure with a photonic band gap in the UV region to 1:1.5 in the case of a 26-layer structure with a photonic band gap in the visible range . The effect of a photonic crystal structure without half-wave layers on the emission spectrum of a liquid crystal display manufactured using IPS technology has been demonstrated in order to reduce the intensity of the blue component to increase the safety of the user's vision. The using of the photonic crystals with two half-wave defective layers allows to achieve complete separation of the spectrum components, which can be used to modify the spectra of large liquid crystal panels, their manufacture using AMOLED technology is a very difficult technological task even for leaders in this field.

scholarly journals Strategies for Dielectric Contrast Enhancement in 1D Planar Polymeric Photonic Crystals

2020 ◽  
Vol 10 (12) ◽  
pp. 4122
Author(s):  
Paola Lova ◽  
Heba Megahd ◽  
Paola Stagnaro ◽  
Marina Alloisio ◽  
Maddalena Patrini ◽  
...  
Keyword(s):  
Photonic Crystals ◽  
High Refractive Index ◽  
Polymer Structure ◽  
Melt Processing ◽  
Air Voids ◽  
Light Confinement ◽  
Low Dielectric ◽  
Dielectric Contrast ◽  
Light Management ◽  
The Common

Historically, photonic crystals have been made of inorganic high refractive index materials coupled to air voids to maximize the dielectric contrast and in turn the light confinement. However, these systems are complex, costly, and time-demanding, and the fabrication processes are difficult to scale. Polymer structures promise to tackle this issue thanks to their easy solution and melt processing. Unfortunately, their low dielectric contrast limits their performance. In this work, we propose a concise but exhaustive review of the common polymers employed in the fabrication of planar 1D photonic crystals and new approaches to the enhancement of their dielectric contrast. Transfer matrix method modeling will be employed to quantify the effect of this parameter in standardized structures and to propose a new polymer structure for applications dealing with light management.

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