Influence Of Light Polarization Research Articles

Optical anisotropy of transparent polymer materials fabricated via 3D printing and their application in photoelasticity

Additive manufacturing has been used to fabricate photoelastic models for several years. In the 3D-printing techniques that use photosensitive resins, models are built layer by layer, and the influence of these layers on light propagation and photoelastic fringes is still ambiguous. In this study, a plane polarization arrangement is used to examine the influence of thin layers on light propagation using three disks printed along different directions. The influence of the layers on the light intensity is negligible for the disk where the layer planes are perpendicular to the direction of light propagation. Identical light polarization is observed for the disks where the layer planes are parallel to the direction of light propagation. This is consistent with a polarizer. The evaluation of the thin layers using scanning electron microscopy indicated that the influence of the microstructures on light propagation is the potential cause of these phenomena. The influence of light polarization on photoelastic fringes was presented by comparing the fringes of different disks under circularly polarized light. The results can improve the application of the 3D-printed models in photoelasticity and the understanding of the optical anisotropy of 3D-printed polymer.

Influence of Light Polarization on Photoswitching of Fulgimide Monolayers on Surfaces

The photoisomerization characteristic parameters [photostationary states (PSSs), cross section σ, and quantum yield η] of indolyl fulgimide compounds dispersed in solution are quantitatively compared to those of the same compounds covalently immobilized as a monolayer on functionalized Si(111) surfaces (see Adv. Mater. 2013, 25, 416). The photoisomerization kinetics of fulgimide compounds in solution is monitored using UV–vis spectroscopy and that of monolayers is monitored by in situ calibrated Fourier transform infrared spectroscopy. Although the isomeric composition at PSSs is very similar in solution and at surfaces, a strong influence of the incident light polarization is found on photoisomerization cross section σ (σs ≪ σp < σsol). Accounting for the local excitation electromagnetic field indicates that the fulgimide groups adopt a preferential tilt angle with respect to the surface normal and their transition dipole is almost parallel to the surface plane for either C or E/Z isomers. Density functi...

Influence of absorption saturation on the shape of CdSe absorption edge

Influence of light polarization on absorption saturation for wurtzite modification CdSe has been investigated. It has been ascertained that the size of blurring the fundamental absorption edge for wurtzite modification CdSe is determined by the non-equilibrium electron filling both the conduction band extremum, when the energy of photons h is higher than the bandgap energy Eg, and the density-of- state tail caused by the presence of static disorder, when the h < Eg. The density-of-state tail resulting from the presence of dynamic disorder is not filled with electrons because of continuous changes of the dynamic potential relief value in time. In the high-energy spectral region, change in the absorption coefficient is limited by the stimulated emission processes.

Influence of light polarization on the analogy between ballistic nanostructures and the electromagnetic field

A set of analogous electron-light parameters for linearly polarized electromagnetic fields has been found for Schrodinger electrons. It is shown that the use of light polarization as an easily controllable parameter offers the possibility of a feasible practical implementation of optical structures with the same reflection coefficient as the corresponding ballistic structures for either Schrodinger or Dirac electrons.

Effect of light polarization on thermal light correlated imaging

Based on the effect of the polarization state of polarized light and the degree of polarization on the second-order correlation function, the influence of light polarization on visibility and signal-to-noise ratio (SNR) is investigated by use of the statistical optics theory. It is shown that only the polarization degree has effect on thermal light correlated imaging. The visibility of correlated imaging is a quadratic function of the polarization degree. An increase in the polarization degree leads to an increase in the SNR of conventional correlated imaging, but the SNR obtained by substracting the background and using the second-order coherent degree is independent of polarization degree.

Influence of light polarization on characteristics of a collinear acoustooptic diffraction

The collinear acoustooptic diffraction of arbitrarily polarized radiation is studied. It is shown that the spectrum of diffracted light at the exit of an acoustooptic cell generally consists of four components, which have different frequencies and polarizations. Beats of these components lead to the modulation of the light passed through an analyzer installed at the exit of the system. Dependences of the amplitudes of components of the passed radiation on the frequency and power of an acoustic wave are studied for different orientations of the polarizer and analyzer.

Influence of light polarization on UV stabilization of prepatterned resists

Details of a mix and match process of thermal nanoimprint lithography and UV lithography have been investigated, where the smaller patterns were defined by imprint, whereas the larger patterns were prepared by UV lithography within the same layer of negative tone resist. Stabilization of the prepatterned resist after imprint by UV curing within the open windows of a mask is different from stabilization under flood exposure. In addition to reflection at the substrate, which leads to a height dependent, vertically modulated exposure dose pattern, the pattern edges, due to diffraction effects, result in an additional lateral modulation of the exposure dose. Distinct local intensity minima and maxima develop within the resist. The intensity differences are particularly strong in the case of pattern widths in the wavelength dimension. Furthermore the direction of light polarization affects the exposure dose pattern. In the case of pattern widths well above the wavelength mainly an underexposure along the edges...

Influence of light polarization on dynamics of all-fiber Raman lasers: theoretical analysis

Using Stokes-vectors formalism, we present a simple model describing steady and dynamic characteristics of all-fiber Raman lasers. This model allows us to describe experimental behaviors that are not yet understood in Raman lasers. In lasers made with standard fibers we show theoretically that weak birefringence and the optical Kerr effect lead to the emergence of unstable regimes similar to those recently observed in experiments [Opt. Lett. 28, 2464 (2003)]. However, the model shows that lasers made with polarization-maintaining fibers are always stable, as evidenced in experiments.

Influence of light polarization on dynamics of continuous-wave-pumped Raman fiber lasers.

The dynamical behavior of cw-pumped Raman fiber lasers is studied experimentally. Lasers made of standard single-mode fibers are found to present unstable behaviors depending on the states of polarization of the Stokes and pump fields. On the contrary, lasers made of polarization-maintaining fibers are found to be always stable. The observed behaviors suggest that birefringence- and Kerr-induced changes in polarization states dramatically affect Raman fiber lasers dynamics.

Influence of Light Polarization on the Behaviour of a Resonant Cascade Laser

A cascade laser model based on a J = 0 M J = 1 M J = 0 ladder atomic-level scheme is proposed. The cases of relative parallel and orthogonal linear field polarizations are studied. The parallel configuration reduces to a three-level cascade laser model in the limit of minimal Zeeman-coherence relaxation rate. Contrarily, the absence of two-photon processes in the orthogonal configuration makes this case equivalent to a pair of incoherently coupled two-level laser models. The stability properties and dynamic behaviour of the orthogonal configuration are analysed.

Dynamics of coherently pumped lasers with linearly polarized pump and generated fields.

The influence of light polarization on the dynamics of an optically pumped single-mode laser with a homogeneously broadened four-level medium is theoretically investigated in detail. Pump and laser fields with either parallel or crossed linear polarizations are considered, as are typical in far-infrared-laser experiments. Numerical simulations reveal dramatically different dynamic behaviors for these two polarization configurations. The analysis of the model equations allows us to find the physical origin of both behaviors. In particular, the crossed-polarization configuration is shown to be effective in decoupling the pump and laser fields, thus allowing for the appearance of Lorenz-type dynamics

High Resolution Laser Techniques Applied to Reaction Dynamics

The applications of high resolution laser techniques to crossed-beam experiments which are examined in this paper concern: (a) the reactivity of atomic/molecular excited states and the influence of light polarization and (b) the measurement of absolute and differential cross sections by use of the laserinduced fluorescence technique performed in a coherent saturation regime.Examples are provided by the crossed-beam study of the Cs(7P) + H2→CsH + H photochemical reaction, where two C.W. single-mode tunable lasers are used to excite Cs atoms and to probe CsH product molecules. It is shown how the fine and hyperfine structures of the Cs atom are involved in the reaction mechanism (harpooning). The measurement of the total cross section (≈4.10−16cm2) gives an indication of the overall efficiency of the reactive process (Cs atoms in the 7P state) with respect to the quenching ones (Cs atoms in 6S, 6P, 5D and 7S states). Finally, the differential cross section shows a marked forward “peaking” of CsH products which narrows with collision energy but which is rather independent of the product rotation.

Influence of light polarization on the dynamics of optically pumped lasers.

The dynamic behavior of a coherently pumped ring laser with a homogeneously broadened four-level medium is analyzed theoretically, considering linearly polarized pump and generated laser beams. The laser is shown to be much more stable when these polarizations are parallel than when they are orthogonal. In the latter case the instability pump threshold can be as low as four times the first laser threshold, and the laser dynamics shows Lorenz-type features.

Near-field Lorenz-Mie theory and its application to microholography

The full near-field Lorenz-Mie theory is described and applied to Gabor microholography to predict the intensities that are recorded on a microholographic plate. The influence of light polarization and the complex refractive index are discussed. Then, the full near-field Lorenz-Mie theory is compared with the Fraunhofer, the Fresnel, and the far-field Lorenz-Mie theories. Criteria of validity of the simplified theories are deduced.

Influence of light polarization on the diffraction efficiency of TIR holograms

Normally when forming a TIR hologram two interference gratings are stored in the recording medium. The object beam interferes with the incoming and with the reflected reference beam. An appropriate selection of the polarization orientations of the interfering light beams leads to the suppression of one of the grating systems. Even to reconstruct TIR hologram it is not all the same in which orientation the reconstructing laser beam is polarized. With the proper selection of the polarization orientations of the forming and reconstructing laser light the diffraction efficiency for TIR holograms can be optimized.