1,721,006 research outputs found
Low-Voltage Tuning in a Nanoparticle/Liquid Crystal Photonic Structure
No full textIn this study, we propose the fabrication and characterization of nanoparticle based multilayer photonic crystals infiltrated with a nematic liquid crystal. We show a very simple infiltration of the liquid crystal in the porous structure, controlled by monitoring the photonic band gap during the infiltration process. Tunability with electric field (by aligning the liquid crystal director) has been observed at very low applied voltage, with a blue shift of the photonic band gap of 8 nm at only 8 V. The presented results could be very interesting for realization of low cost and portable switching devices for high density integrated optics
Infiltration of E7 Liquid Crystal in a Nanoparticle-Based Multilayer Photonic Crystal: Fabrication and Electro-optical Characterization
No full textIn this study, we propose the fabrication and the electro-optical characterization of nanoparticle-based multilayer photonic crystals infiltrated with a nematic liquid crystal. Two methods of the photonics band gap tunability have been proposed. In the first, we have observed an aligning of the liquid crystal director along the external electric field vector at very low applied voltage, with a blue shift of the photonic band gap of 8nm at only 8Vrms. In the second, we put forward the possibility of tuning the photonic band gap of the porous multilayer just by infiltration of appropriate liquid crystals, in accordance with results carried out by a custom simulation software. The presented device could be very interesting for applications where high sensitivity sensor and selective color tunability is needed with the use of cheap and low-voltage power supplies
Optical Manipulation in Liquid Crystals: Effects of Tight Focusing on Nonlinear Optical Reorientation
No full textCompact Lasers Based on HPDLC Gratings
No full textWe report the fabrication technique and the main emission properties of two novel all-organic laser devices based on high-resolution reflection gratings written on holographic polymer-dispersed liquid crystal materials by means of conventional holographic techniques. The first type of laser is based upon a distributed Bragg-reflector configuration whereas the second one makes use of a distributed-feedback configuration. Different monomer/liquid-crystal/ photoinitiator mixtures are analysed and the main parameters affecting the grating reflectivity and the overall performances of these plastic mirrorless laser device are discussed
Spectral analysis of shrinkage in holographic material suitable for optical storage applications
No full textLight Transmission Properties and Shannon Index in One-Dimensional Photonic Media With Disorder Introduced by Permuting the Refractive Index Layers
Get PDFIn this paper, we have studied, with a numerical method, how introducing disorder affects the light transmission properties of 1-D photonic structures over a wide range of wavelengths. A new type of disorder is introduced by permuting the refractive index layers in the optical medium. We compared the light transmission properties of ideal photonic crystals and of disordered media with the same kind and number of scattering elements for different sample lengths. We have calculated the transmission properties, by the transfer matrix method, of thousands of different disordered structures in order to perform a statistical analysis. We found that, below a certain sample length, disorder induces less average light reflection than ordered structures, whereas above the threshold length, disordered structures show more average reflection. Moreover, we have quantified the disorder of the structures with the Shannon index. We have found a decrease in the average light transmission as a function of the Shannon index. Furthermore, the sample length affects the trend of the average transmission as a function of the Shannon index
Light amplification by dye-doped holographic polymer dispersed liquid crystals
No full text(selected for June 7, 2004 issue of Virtual Journal of Nanoscale Science & Technology)
In this letter we report a “one-step” fabrication technique of an optical active organic photonic band gap (PBG) structure allowing the onset of the amplification spontaneous emission effect and narrowing of the corresponding band. This result has been achieved through the addition of the dye rhodamine 6G to a standard holographic polymer dispersed liquid crystal pre-polymer mixture. The effects of the dye addition on the optical properties of the polymerized PBG structure have been analyzed. The spectra emitted by this optically active periodic structure have been studied as a function of the excitation energy
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