scholarly journals Linear Birefringent Films of Cellulose Nanocrystals Produced by Dip-Coating

Nanomaterials ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 45 ◽  
Author(s):  
Arturo Mendoza-Galván ◽  
Tania Tejeda-Galán ◽  
Amos Domínguez-Gómez ◽  
Reina Mauricio-Sánchez ◽  
Kenneth Järrendahl ◽  
...  
Keyword(s):  
Cellulose Nanocrystals ◽  
Polarized Light ◽  
Normal Incidence ◽  
Dip Coating ◽  
Mueller Matrix ◽  
Linear Birefringence ◽  
Transparent Films ◽  
Sample Rotation ◽  
Glass Substrates ◽  
Linearly Polarized

Transparent films of cellulose nanocrystals (CNC) are prepared by dip-coating on glass substrates from aqueous suspensions of hydrolyzed filter paper. Dragging forces acting during films’ deposition promote a preferential alignment of the rod-shaped CNC. Films that are 2.8 and 6.0 µm in thickness show retardance effects, as evidenced by placing them between a linearly polarized light source and a linear polarizer sheet in the extinction configuration. Transmission Mueller matrix spectroscopic ellipsometry measurements at normal incidence as a function of sample rotation were used to characterize polarization properties. A differential decomposition of the Mueller matrix reveals linear birefringence as the unique polarization parameter. These results show a promising way for obtaining CNC birefringent films by a simple and controllable method.

scholarly journals Quantification of Optical Chirality in Cellulose Nanocrystal Films Prepared by Shear-Coating

2021 ◽  
Vol 11 (13) ◽  
pp. 6191
Author(s):  
Olga Rubí Juárez-Rivera ◽  
Reina Araceli Mauricio-Sánchez ◽  
Kenneth Järrendahl ◽  
Hans Arwin ◽  
Arturo Mendoza-Galván
Keyword(s):  
Self Assembly ◽  
Polarized Light ◽  
Mueller Matrix ◽  
Cellulose Nanocrystal ◽  
Free Standing ◽  
Full Characterization ◽  
Glass Substrates ◽  
Left Handed ◽  
Optical Chirality ◽  
Transmission Modes

Evaporation-induced-self-assembly is widely used to produce chiral cellulose nanocrystal (CNC) free-standing films reflecting left-handed polarized light. Research on supported chiral CNC films is rather scarce. The reflection and/or transmission of unpolarized light are the most common optical techniques used to characterize the selective reflection of CNC films whereas the use of techniques to quantify chiral properties is limited. Here, the fabrication of chiral CNC films supported on glass substrates by a shear-coating method, as well as a full characterization of their polarization properties, are reported. Optical chirality is evidenced in films, showing a brilliant blue structural color when viewed through a left-handed polarizer and darkness through a right-handed polarizer. Mueller-matrix data in the reflection and transmission modes are used to quantitatively characterize the structural origin of color in the films. The quantification of the linear and circular birefringence, as well as circular dichroism, is performed by analytical inversion of the Mueller matrix data in the transmission mode and regression analysis using Tellegen constitutive equations. The equivalence of the two methods to quantify the structural chirality in CNC films is demonstrated. The swelling of films in water and kinetics during drying is studied by reflection spectroscopy.

Specific Futures of Optical Anisotropy in Terbium Iron and Terbium Gallium Garnets

2014 ◽  
Vol 605 ◽  
pp. 553-556
Author(s):  
Natalia Tsidaeva ◽  
Viktorija Abaeva ◽  
Anatoly Turiev ◽  
Elena Enaldieva ◽  
Tengiz Butkhuzi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Energy Levels ◽  
Strong Dependence ◽  
Polarized Light ◽  
Magnetization Vector ◽  
Linear Dichroism ◽  
Linear Birefringence ◽  
Optical Channels ◽  
Linearly Polarized ◽  
Magnetic Linear Dichroism

We reported magnetooptical properties of Tb3+in single crystals of Tb3Fe5O12and Tb3Ga5O12for ion occupying sites of D2symmetry in the garnets structure. It is shown that in the employed Voigt geometry the magnetic linear birefringence and the dichroism reach values 10-4, and have a strong dependence on the wavelength and a strong anisotropy. The absorption spectra were obtained at temperatures of 30K, 100K using magnetic field up to 25 kOe applied parallel and perpendiculare to the electric vector E linearly polarized light on the7F67F0and7F67F1optical transitions region. The aim of this research was revealing of a role of contributions of exchange interaction and a crystal field in splitting of energy levels of the basic condition7F6ion Tb3+multiplet in Tb ferrite-garnet by studying of character of spectra magnetic linear dichroism (MLD) paramagnetic and ferrimagnetic crystals placed in an external magnetic field. More over, the assumption about nonreciprocity of magnetic linear birefringence (MLB) spectra and dichroism with the change of the relative orientation of the magnetization vector I and the light wave vector has been experimentally confirmed. This effect may use as a base for the design of the different transducers, for example, magnetooptical optical channels commutator.

Efficient planar plasmonic directional launching of linearly polarized light in a catenary metasurface

2020 ◽  
Vol 22 (47) ◽  
pp. 27554-27559
Author(s):  
Panpan Chen ◽  
Cong Chen ◽  
Saisai Qin ◽  
Jianxin Xi ◽  
Wanxia Huang ◽  
...  
Keyword(s):  
Extinction Ratio ◽  
Polarized Light ◽  
Normal Incidence ◽  
Linearly Polarized

Under the normal incidence of p-polarized light at 750 nm, the numerical extinction ratio reached up to 35 dB and the measured extinction ratio reached up to 24 dB.

Anisotropy of the Linear Magnetic Birefridence of Europium Iron Garnet

2014 ◽  
Vol 605 ◽  
pp. 548-552
Author(s):  
Natalia Tsidaeva ◽  
Viktorija Abaeva ◽  
Anatoly Turiev ◽  
Elena Enaldieva ◽  
Tengiz Butkhuzi ◽  
...  
Keyword(s):  
Single Crystal ◽  
Polarized Light ◽  
Magnetization Vector ◽  
Linear Dichroism ◽  
Linear Birefringence ◽  
Optical Channels ◽  
Iron Garnets ◽  
Linearly Polarized ◽  
Magnetic Linear Dichroism ◽  
Iron Garnet

The results of investigation of magnetic linear birefringence (MLB) and magnetic linear dichroism (MLD) of Eu3Fe5O12(EuIG) iron garnet on7F07F6optical transitions upon variation of the directions of the magnetization vector I relative to the electric vector E linearly polarized light that propagates through single crystal iron garnets are presented. The measurements were made on Eu3Fe5O12single-crystal samples in the form of plates 100 μm thick cut in the (110) and (100) plane at the temperatures T = 82 and in a magnetic field H= 25 kOe. The absorption spectra of the linearly polarized light were studied. It is shown that MLB and dichroism in the region of the7F07F6absorption band reach values 10-3. First experimentally discovered nonreciprocity of MLB spectra and dichroism with the change of the relative orientation of the magnetization vector I and the light wave vector. This effect may use as a base for the design of the different transducers, for example, magnetooptical optical channels commutator.

On resolving fine periodic microstructures in the optical microscope

1989 ◽  
Vol 47 ◽  
pp. 364-365
Author(s):  
W.S. Putnam ◽  
C. Viney
Keyword(s):  
Liquid Crystalline ◽  
Numerical Aperture ◽  
Polarized Light ◽  
Normal Incidence ◽  
Optical Microscope ◽  
Angle Of Incidence ◽  
Resolution Limit ◽  
Crystalline Materials ◽  
Periodic Microstructures ◽  
Liquid Crystalline Materials

Many sheared liquid crystalline materials (fibers, films and moldings) exhibit a fine banded microstructure when observed in the polarized light microscope. In some cases, for example Kevlar® fiber, the periodicity is close to the resolution limit of even the highest numerical aperture objectives. The periodic microstructure reflects a non-uniform alignment of the constituent molecules, and consequently is an indication that the mechanical properties will be less than optimal. Thus it is necessary to obtain quality micrographs for characterization, which in turn requires that fine detail should contribute significantly to image formation.It is textbook knowledge that the resolution achievable with a given microscope objective (numerical aperture NA) and a given wavelength of light (λ) increases as the angle of incidence of light at the specimen surface is increased. Stated in terms of the Abbe resolution criterion, resolution improves from λ/NA to λ/2NA with increasing departure from normal incidence.

PREPARATION AND CHARACTERIZATION OF POLYVINYL ALCOHOL THIN FILMS FOR ORGANIC THIN FILM TRANSISTORS AND BIOMEDICAL APPLICATIONS

2018 ◽  
Vol 5 (2) ◽  
pp. 16-18
Author(s):  
Chandar Shekar B ◽  
Ranjit Kumar R ◽  
Dinesh K.P.B ◽  
Sulana Sundar C ◽  
Sunnitha S ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Thin Film Transistors ◽  
Gravimetric Method ◽  
Dip Coating ◽  
Organic Thin Film Transistors ◽  
Poly Vinyl Alcohol ◽  
Organic Thin Film ◽  
Glass Substrates ◽  
Coating Method

Thin films of poly vinyl alcohol (PVA) were prepared on pre-cleaned glass substrates by Dip Coating Method. FTIR spectrum was used to identify the functional groups present in the prepared films. The vibrational peaks observed at 1260 cm-1 and 851 cm-1 are assigned to C–C stretching and CH rocking of PVA.The characteristic band appearing at 1432 cm-1 is assigned to C–H bend of CH2 of PVA. The thickness of the prepared thin films were measured by using an electronic thickness measuring instrument (Tesatronic-TTD20) and cross checked by gravimetric method. XRD spectra indicated the amorphous nature of the films.Surface morphology of the coated films was studied by scanning electron microscope (SEM). The surface revealed no pits and pin holes on the surface. The observed surface morphology indicated that these films could be used as dielectric layer in organic thin film transistors and as drug delivery system for wound healing.

scholarly journals Metasurface of Combined Semicircular Rings with Orthogonal Slit Pairs for Generation of Dual Vector Beams

Nanomaterials ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 1718
Author(s):  
Qian Kong ◽  
Manna Gu ◽  
Xiangyu Zeng ◽  
Rui Sun ◽  
Yuqin Zhang ◽  
...  
Keyword(s):  
Time Domain ◽  
Finite Difference Time Domain ◽  
Polarized Light ◽  
Orientation Angle ◽  
Fdtd Simulation ◽  
Dual Vector ◽  
Vector Beams ◽  
Linearly Polarized ◽  
Potential Applications ◽  
Difference Time

Manipulation of multichannel vector beams (VBs) with metasurfaces is an important topic and holds potential applications in information technology. In this paper, we propose a novel metasurface for the generation of dual VBs, which is composed of orthogonal slit pairs arranged on multiple groups of combined semicircular rings (CSRs). A group of CSRs include a right-shifted set and a left-shifted set of semicircular rings, and each set of semicircular rings has two halves of circles with different radii, sharing the same shifted center. Under the illumination of linearly polarized light, the two shifted sets of semicircular rings generate the two VBs at the shifted center positions on the observation plane. The slit units of each set are designed with independent rotation order and initial orientation angle. By adjusting the linear polarization of illumination, both two VBs with their orders and polarization states are independently controlled simultaneously. The principle and design are demonstrated by the finite-difference time domain (FDTD) simulation. The work is of significance for miniatured devices of VB generators and for related applications.

scholarly journals Formation of half-period surface relief gratings in azobenzene containing polymer films

2020 ◽  
Vol 126 (9) ◽  
Author(s):  
Joachim Jelken ◽  
Carsten Henkel ◽  
Svetlana Santer
Keyword(s):  
Polymer Film ◽  
Polymer Films ◽  
Surface Relief ◽  
Incident Light ◽  
Glassy State ◽  
Polarized Light ◽  
Half Period ◽  
Polarization Distribution ◽  
Linearly Polarized ◽  
Set Up

Abstract We study the peculiar response of photo-sensitive polymer films irradiated with a certain type of interference pattern where one interfering beam is S-polarized, while the second one is P-polarized. The polymer film, although in a glassy state, deforms following the local polarization distribution of the incident light, and a surface relief grating (SRG) appears whose period is half the optical one. All other types of interference patterns result in the matching of both periods. The topographical response is triggered by the alignment of photo-responsive azobenzene containing polymer side chains orthogonal to the local electrical field, resulting in a bulk birefringence grating (BBG). We investigate the process of dual grating formation (SRG and BBG) in a polymer film utilizing a dedicated set-up that combines probe beam diffraction and atomic force microscopy (AFM) measurements, and permits acquiring in situ and in real-time information about changes in local topography and birefringence. We find that the SRG maxima appear at the positions of linearly polarized light (tilted by 45° relative to the grating vector), causing the formation of the half-period topography. This permits to inscribe symmetric and asymmetric topography gratings with sub-wavelength period, while changing only slightly the polarization of one of the interfering beams. We demonstrate an easy generation of sawtooth profiles (blazed gratings) with adjustable shape. With these results, we have taken a significant step in understanding the photo-induced deformation of azo-polymer films.

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