Generation of Circularly Polarized Light of Highly Oriented Poly(P-Phenylene Vinylene)

2000 ◽  
Vol 660 ◽  
Author(s):  
A. Marletta ◽  
D. Gonçalves ◽  
O. N. Oliveira ◽  
R. M. Faria ◽  
F. E. G. Guimarães
Keyword(s):  
Polarized Light ◽  
Linear Dichroism ◽  
Asymmetry Factor ◽  
Phenylene Vinylene ◽  
Lb Films ◽  
Circularly Polarized Light ◽  
Langmuir Blodgett ◽  
Efficient Energy ◽  
Absorption Experiment ◽  
Linearly Polarized

ABSTRACTLangmuir-Blodgett (LB) films of poly(p-phenylene vinylene) (PPV) were prepared using an amphiphilic precursor, where the counterion chloride was partially replaced by a long chain dodecylbenzenesulfonate ion. These LB-PPV films are highly ordered along the dipping direction as demonstrated by linear dichroism experiments using linearly polarized optical absorption and emission. The intensity ratio between emitted light parallel and perpendicular to the dipping direction was ca. 17, which is much higher than the dichroic ratio of 3.6 found in the polarized absorption experiment. These values indicate an efficient energy and/or charge transfer between low conjugated segments (disordered) and highly conjugated (ordered) ones after excitation. In addition, the LB films displayed large circular polarization with an asymmetry factor ge which varies from 0.6 to –0.2 when the sample temperature is increased from 30 to 300 K.

UNPOLAR AND POLAR HOLOGRAPHIC GRATING RECORDING BY CIRCULARLY POLARIZED LIGHT ON PHOTOANISOTROPIC AZOBENZENE LANGMUIR–BLODGETT FILMS

2003 ◽  
Vol 12 (04) ◽  
pp. 495-511 ◽  
Author(s):  
L. M. BLINOV ◽  
R. BARBERI ◽  
F. CIUCHI ◽  
M. P. DE SANTO ◽  
G. CIPPARRONE ◽  
...  
Keyword(s):  
Probe Beam ◽  
Optical Anisotropy ◽  
Polarized Light ◽  
Spatial Modulation ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Langmuir Blodgett ◽  
Linearly Polarized ◽  
Langmuir Blodgett Films ◽  
Ion Laser

A comparative study of photo-induced optical anisotropy was carried out on Langmuir–Blodgett films prepared from five different amphiphilic azobenzene derivatives. The anisotropy was induced by a linearly polarized pump beam of an Ar-ion laser at λ=514 nm and monitored by a linearly polarized probe beam of a He–Ne laser at λ=633 nm . Large optical anisotropy up to 0.35 has been induced. Holographic gratings were recorded by two left circularly polarized beams of the Ar-ion laser and time evolution of the first-order diffraction efficiency of the probe beam was recorded in an automatic regime. In such a geometry, the spatial modulation of refraction index reaches 0.14. The experimental data is consistent with a model for a photo-induced collective chromophore realignment in the heterogeneous domain structure of the films studied. The influence of an electric field of the corona discharge on the grating recording process was also studied and polar diffraction gratings have been prepared by a spatially periodic photo-poling process.

Polyamic Acid Langmuir-Blodgett (LB) Films Containing A Stable Second-Order NLO Chromophore

1995 ◽  
Vol 413 ◽  
Author(s):  
D. W. Cheong ◽  
J. -I Chen ◽  
J. Kumar ◽  
S. K. Tripathy
Keyword(s):  
Nonlinear Coefficient ◽  
Polarized Light ◽  
Second Order ◽  
Polyimide Films ◽  
Polyamic Acid ◽  
Lb Films ◽  
Langmuir Blodgett ◽  
Number Of Layers ◽  
Absorption Correction ◽  
Nlo Chromophores

ABSTRACTNonlinear optical (NLO) LB films of polyamic acid containing a stable NLO dye were prepared and imidized either chemically or thermally. The optical properties and molecular orientation of these LB films were studied. From the absorption spectra, we infer that the derivative of the pnitroazobenzene chromophore covalently attatched to polyamic acid did not show significant aggregation. Quadratic dependence of SHG on the number of layers in polyamic acid films indicated the noncentrosymmetric organization of polar NLO chromophores. A second-order nonlinear coefficient (d33) of 23.4 pm/V was observed at 1064 nm after absorption correction. In polyimide films, SH intensity was dramatically reduced due to the collapse of the layered structure upon imidization process. In-plane isotropy of the LB films of polyamic acid and polyimide were lost upon irradiation of polarized light.

scholarly journals Patterns and properties of polarized light in air and water

2011 ◽  
Vol 366 (1565) ◽  
pp. 619-626 ◽  
Author(s):  
Thomas W. Cronin ◽  
Justin Marshall
Keyword(s):  
Polarized Light ◽  
Natural Scenes ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Current State ◽  
Visual Systems ◽  
The Earth ◽  
Predictable Pattern ◽  
Linearly Polarized ◽  
Polarization Of Light

Natural sources of light are at best weakly polarized, but polarization of light is common in natural scenes in the atmosphere, on the surface of the Earth, and underwater. We review the current state of knowledge concerning how polarization and polarization patterns are formed in nature, emphasizing linearly polarized light. Scattering of sunlight or moonlight in the sky often forms a strongly polarized, stable and predictable pattern used by many animals for orientation and navigation throughout the day, at twilight, and on moonlit nights. By contrast, polarization of light in water, while visible in most directions of view, is generally much weaker. In air, the surfaces of natural objects often reflect partially polarized light, but such reflections are rarer underwater, and multiple-path scattering degrades such polarization within metres. Because polarization in both air and water is produced by scattering, visibility through such media can be enhanced using straightforward polarization-based methods of image recovery, and some living visual systems may use similar methods to improve vision in haze or underwater. Although circularly polarized light is rare in nature, it is produced by the surfaces of some animals, where it may be used in specialized systems of communication.

Synthesis and Fabrication of Aligned Conjugated Polymer Thin Films

2012 ◽  
Vol 706-709 ◽  
pp. 1636-1641 ◽  
Author(s):  
Takashi Hirahara ◽  
Masahiro Yoshizawa-Fujita ◽  
Yuko Takeoka ◽  
Masahiro Rikukawa
Keyword(s):  
Functional Groups ◽  
Thermal Annealing ◽  
Conjugated Polymer ◽  
Polarized Light ◽  
Linear Dichroism ◽  
Side Chains ◽  
Absorption Region ◽  
Linearly Polarized ◽  
Cotton Effects ◽  
External Stimuli

Fluorene-thiophene copolymers having chiral and azobenzene substituents, PAzB4-T, were synthesized by the Pd-catalyzed Suzuki coupling method. We studied the aligning organization of the main chain of PAzB4-T with the activation of the attached functional groups by thermal annealing and photo-annealing processes. Circular dichroism (CD) measurements revealed that the thermally annealed PAzB4-T spin-coated films exhibited bisignate Cotton effects over the absorption regions of the polymer main chains and the azobenzene side chains due to the formation of chiral assemblies. After the photo-annealing process, which means linearly polarized light irradiation accompanied by thermal annealing, the PAzB4-T spin-coated films showed linear dichroism over the absorption region of the main chains, due to the alignment of azobenzene side chains against the electric field of the linearly polarized light. These results suggested that rigid conjugated polymers were successfully aligned by the alignment of functional groups with the external stimuli.

Laser manipulation in liquid crystals: an approach to microfluidics and micromachines

2006 ◽  
Vol 364 (1847) ◽  
pp. 2789-2805 ◽  
Author(s):  
Helen F Gleeson ◽  
Tiffany A Wood ◽  
Mark Dickinson
Keyword(s):  
Liquid Crystals ◽  
Liquid Crystalline ◽  
Polarized Light ◽  
Three Dimensions ◽  
Laser Tweezers ◽  
Fluid Medium ◽  
Circularly Polarized Light ◽  
Viscosity Coefficients ◽  
Linearly Polarized ◽  
Local Shear

Laser trapping of particles in three dimensions can occur as a result of the refraction of strongly focused light through micrometre-sized particles. The use of this effect to produce laser tweezers is extremely common in fields such as biology, but it is only relatively recently that the technique has been applied to liquid crystals (LCs). The possibilities are exciting: droplets of LCs can be trapped, moved and rotated in an isotropic fluid medium, or both particles and defects can be trapped and manipulated within a liquid crystalline medium. This paper considers both the possibilities. The mechanism of transfer of optical angular momentum from circularly polarized light to small droplets of nematic LCs is described. Further, it is shown that droplets of chiral LCs can be made to rotate when illuminated with linearly polarized light and possible mechanisms are discussed. The trapping and manipulation of micrometre-sized particles in an aligned LC medium is used to provide a measure of local shear viscosity coefficients and a unique test of theory at low Ericksen number in LCs.

Generation of Circularly Polarized Light of Highly Oriented Poly( P-Phenylene Vinylene)

2000 ◽  
Vol 660 ◽  
Author(s):  
A. Marletta ◽  
D. Gonçalves ◽  
O. N. Oliveira ◽  
R. M. Faria ◽  
F. E. G. Guimarães
Keyword(s):  
Polarized Light ◽  
Phenylene Vinylene ◽  
Circularly Polarized Light ◽  
Circularly Polarized

scholarly journals Multifunctional Metasurface Lens With Tunable Focus Based on Phase Transition Material

2021 ◽  
Vol 9 ◽  
Author(s):  
Yongkang Song ◽  
Weici Liu ◽  
Xiaolei Wang ◽  
Faqiang Wang ◽  
Zhongchao Wei ◽  
...  
Keyword(s):  
Phase Transition ◽  
Light Field ◽  
Focal Point ◽  
Incident Light ◽  
Polarization State ◽  
Polarized Light ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Multiple Focus ◽  
Linearly Polarized

Metasurfaces have powerful light field manipulation capabilities, which have been extensively studied in the past few years and have developed rapidly in various fields. At present, the focus of metasurface research has shifted to the tunable functionality. In this paper, a temperature-controllable multifunctional metasurface lens based on phase transition material is designed. First of all, by controlling the temperature of the desired working area and the polarization of the incident light, switching among multiple focus, single focus, and no focus at any position can be achieved, and the intensity and helicity of the output light can be adjusted. In addition, a polarization-sensitive intensity-tunable metalens based on the P-B phase principle is designed, when the incident light is linearly polarized light, left-handed circularly polarized light, or right-handed circularly polarized light, it has the same focal point but with different light field intensities. Therefore, the focused intensity can be tunable by the polarization state of the incident light.

EVE polarization lidar: ESA’s ground reference system for Aeolus L2A products Cal/Val

2021 ◽  
Author(s):  
Peristera Paschou ◽  
Nikolaos Siomos ◽  
Vassilis Amiridis ◽  
Volker Freudenthaler ◽  
George Georgoussis ◽  
...  
Keyword(s):  
Polarized Light ◽  
Backscatter Coefficient ◽  
Lidar System ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Polarized Emission ◽  
Linearly Polarized ◽  
Reference Measurements ◽  
Backscattered Signals ◽  
Aerosol Types

<p>The EVE (Enhancement and Validation of ESA products) lidar is a mobile, ground-based, polarization lidar system, developed to provide ground reference measurements for the validation of the Aeolus L2A products. The system utilizes a dual-laser/dual-telescope configuration that emits linearly and circularly polarized light at 355 nm  interleaved and detects the linear and circular depolarization on the backscattered signals as well as the Raman backscattering at 387 nm. Consequently, the particle optical properties of backscatter coefficient, extinction coefficient, linear and circular depolarization ratios can be measured by the lidar. Moreover, the system’s dual configuration enables to mimic both the operation of ALADIN on board Aeolus that relies on the circularly polarized emission and the operation of a polarization lidar system with linearly polarized emission. Besides EVE’s main goal of the Aeolus L2A products performance evaluation under a wide variety of aerosol types, EVE can also validate the linear to circular depolarization conversions, which have to be used for the harmonization of the linearly polarized lidar systems with Aeolus, and as such, to evaluate any possible biases of the efforts of these systems on Aeolus L2A validation.</p>

scholarly journals Tomographic reconstruction of circularly polarized high-harmonic fields: 3D attosecond metrology

2016 ◽  
Vol 2 (2) ◽  
pp. e1501333 ◽  
Author(s):  
Cong Chen ◽  
Zhensheng Tao ◽  
Carlos Hernández-García ◽  
Piotr Matyba ◽  
Adra Carr ◽  
...  
Keyword(s):  
Extreme Ultraviolet ◽  
Tomographic Reconstruction ◽  
High Harmonic ◽  
Polarized Light ◽  
Copper Surface ◽  
Photoelectron Spectra ◽  
Laser Fields ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Linearly Polarized

Bright, circularly polarized, extreme ultraviolet (EUV) and soft x-ray high-harmonic beams can now be produced using counter-rotating circularly polarized driving laser fields. Although the resulting circularly polarized harmonics consist of relatively simple pairs of peaks in the spectral domain, in the time domain, the field is predicted to emerge as a complex series of rotating linearly polarized bursts, varying rapidly in amplitude, frequency, and polarization. We extend attosecond metrology techniques to circularly polarized light by simultaneously irradiating a copper surface with circularly polarized high-harmonic and linearly polarized infrared laser fields. The resulting temporal modulation of the photoelectron spectra carries essential phase information about the EUV field. Utilizing the polarization selectivity of the solid surface and by rotating the circularly polarized EUV field in space, we fully retrieve the amplitude and phase of the circularly polarized harmonics, allowing us to reconstruct one of the most complex coherent light fields produced to date.

Depolarization of Light by Mono-Dispersed Air Bubbles Coated With Carbonaceous Particles

2003 ◽  
Author(s):  
Basil T. Wong ◽  
Rodolphe Vaillon ◽  
M. Pinar Mengu¨c¸
Keyword(s):  
Polarized Light ◽  
Incident Radiation ◽  
Air Bubbles ◽  
Carbonaceous Particles ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Cylindrical System ◽  
Coal Particles ◽  
Linearly Polarized ◽  
Depolarization Of Light

In this paper, the potential use of polarized light for characterization of mono-dispersed air bubbles coated with carbonaceous particles is investigated using a vector Monte Carlo approach. The medium is assumed to be water, loaded with highly-forward scattering ash and coal particles, as well as absorbing and scattering air bubbles coated with a thin carbonaceous (soot) layer. A polarized laser beam is assumed to impinge normally on a cylindrical system at the circumferential surface, and the scattered signals are assumed to be collected within the same plane. The scattering matrix for the entire medium is constructed based on the Fresnel equations. Examination of the absorbing and multiple-scattering results show that if circularly polarized light is used, the bubble size, the bubble separation, as well as the thickness of carbonaceous layer around bubbles can be determined if careful experiments are conducted. It is shown that circularly polarized light is a better choice than the linearly polarized incident radiation for the present diagnosis objectives.

Sign in / Sign up

Export Citation Format

Share Document