Search results for "OPTICS"

Hybrid silicon on insulator/polymer electro-optical intensity modulator operating at 780  nm

2014

Currently inorganic materials prevail as the nonlinear active medium for light modulation in electro-optical (EO) device technology. A recent promising trend is to consider organic nonlinear optical materials for application in EO modulators due to their multiple advantages including low costs and high EO coefficients. In this paper, we proposed a new type of polymer EO modulator whose fabrication is compatible with the currently used silicon on insulator technology. Our numerical optimization of the proposed structure demonstrates that it is theoretically possible to achieve a half-wave voltage as low as 1.56 V for a 1 cm long modulator structure operating at 780 nm. Based on the results o…

Spatial scale-dependent tracer diffusion in bulk polycarbonate studied by holographic relaxation.

2005

The diffusion of a photochromic dye tracer in polycarbonate was studied by a holographic relaxation technique (forced Rayleigh scattering) at temperatures close to the glass transition temperature. By varying the holographic grating period the results could be interpreted via the spatial scale dependence of apparent diffusion coefficients within a two-state diffusion model. This indicates inhomogeneities on the scale of a few micrometers in the polymer glass.

Study of interacting bands of silane: Analysis of infrared and Raman spectra

1990

Abstract The ν 1 ν 3 interacting bands of natural silane have been studied by Fourier transform spectroscopy and stimulated Raman spectroscopy, respectively, in the regions 2040–2320 and 2180–2187 cm−1. These data combined with available microwave observations have been analyzed using a reduced effective Hamiltonian developed through the fifth order for 28SiH4 and through the fourth order for 29SiH4 and 30SiH4. The observed infrared and Raman transitions have been very well reproduced with a standard deviation of about 0.0004 cm−1 for 28SiH4. Some anomalies in the Hamiltonian expansion have been found, but they did not perturb the analysis.

Elastic Properties of Liquid Crystal Elastomer Balloons

2001

We introduce a method to measure elastic properties of smectic liquid crystalline elastomers. Freely suspended smectic polymer films containing photoreactive groups are inflated to spherical bubbles and crosslinked by UV light irradiation. After crosslinking, the balloon volume is varied and elastic properties of the material are determined from the relation between radius and inner excess pressure. The influence of the network topology on the elastic behaviour is discussed.

NLO-polymers containingtert-butyloxycarbonyl protecting groups: Modification after processing leading to thermally stable nonlinear optical materials

1997

Direct Surface Relief Formation in Polymer Films

2013

Due to active development of nanoelectronics, the studies of methods of nanorelief surface formation in different materials, in particular polymers are very important. Organic polymer films in consequence of their dielectric and optical properties have been used as basis of these devices. In this paper, the possibility of UV optical record and electron beam lithography in different type of polymeric films was studied. Mechanisms of molecular structure changes: photoisomerization, destruction, cross-linking and oxidation have been discussed. The results of UV illumination of polyurethanes, polyacrylates, and some block-copolymers were described. The element analysis of polybutadiene block co…

UV optical record and electron beam lithography in polymer films

2012

Possibility of UV optical record and electron beam lithography in different type of organic polymer films was studied. Mechanisms of molecular structure changes: photoisomerization, destruction, cross-linking and oxidation have been discussed. The results of UV illumination of polyurethanes, polyacrilates, and some block-copolymers are described. The element analysis of polyisoprene block copolymer was performed before and after UV illumination, and the changes in transmission spectra of the polymer film were measured. The resolution of electron beam lithography on polymer films was studied. In the polyisoprene block copolymer film the oxidation polymerization was ascertain at UV-illuminati…

Relationship between structure and electroluminescence of oligo(p-phenylenevinylene)s

1998

The preparation of LEDs with poly(p-phenylenevinylene) (PPV) as emitting material is well established, However, due to the presence of a distribution of conjugated chain lengths in the polymer, systematic investigations of the electroluminescence with polymeric materials are difficult, as far as the optical emission is concerned. We are studying the relationship between structural variation of substituted oligo(p-phenylenevinylene)s and their electroluminescent behaviour using a series of distyrylbenzenes with a variety of substituents in order to investigate their influence on the electroluminescence (EL). Furthermore, we synthesized a homologous series of monodisperse oligo(2,5-dipropoxy-…

Effects of inhomogeneities of cross-links on a microphase separation of polymer mixtures

1994

We generalize de Gennes' theory of the microphase separation of cross-linked polymer mixtures to take into account the spatial fluctuations of the elasticity constant c, preventing the mixture from complete segregation. Within a mean-field analysis we found that the spatial fluctuations of c(r), which are assumed to obey the Poisson distribution, enlarge the size of the domains. The latter is obtained to be temperature dependent.


Photoreactive Langmuir–Blodgett–Kuhn multilayer assemblies from functionalized liquid-crystalline side chain polymers, I. Homopolymers containing azo…

1991

Stable monomolecular layers of a liquid-crystalline homopolymer bearing azobenzene chromophores in the mesogenic side groups could be prepared at the water–air interface by slow compression at room temperature. From the area per monomer unit of A0≈0.25 nm2 a structural model with tightly packed azobenzene groups oriented nearly parallel to the surface normal was deduced. After transfer to a solid support in a Y-type mode the obtained Langmuir–Blodgett–Kuhn (LBK) multilayer assemblies of varying thicknesses (from a double layer to a thick film of d = 238 nm, capable of guiding optical modes) were prepared and analyzed by X-ray reflection and optical evanescent wave techniques. A monolayer th…