Magneto-controlled nonlinear optical materials

We exploit theoretically a magneto-controlled nonlinear optical material which contains ferromagnetic nanoparticles with a non-magnetic metallic nonlinear shell in a host fluid. Such an optical material can have anisotropic linear and nonlinear optical properties and a giant enhancement of nonlinearity, as well as an attractive figure of merit.Comment: 11 pages, 2 figures. To be published in Appl. Phys. Let

Structured Optical Materials Controlled by Light

Materials of which the optical response is determined by their structure are of much interest both for their fundamental properties and applications. Examples range from simple gratings to photonic crystals. Obtaining control over the optical properties is of crucial importance in this context, and it is often attempted by electro-optical effect or by using magnetic fields. In this paper, we introduce the use of light to switch and tune the optical response of a structured material, exploiting a physical deformation induced by light itself. In this new strategy, light drives an elastic reshaping, which leads to different spectral properties and hence to a change in the optical response. This is made possible by the use of liquid crystalline networks structured by Direct Laser Writing. As a proof of concept, a grating structure with sub-millisecond time-response is demonstrated for optical beam steering exploiting an optically induced reversible shape-change. Experimental observations are combined with finite-element modeling to understand the actuation process dynamics and to obtain information on how to tune the time and the power response of this technology. This optical beam steerer serves as an example for achieving full optical control of light in broad range of structured optical materials

Helmholtz solitons in power-law optical materials

A nonlinear Helmholtz equation for optical materials with regimes of power-law type of nonlinearity is proposed. This model captures broad beam evolution at any angle with respect to the reference direction in a wide range of media, including some semiconductors, doped glasses and liquid crystals. Novel exact analytical soliton solutions are presented for a generic nonlinearity, within which known Kerr solitons comprise a subset. Three conservation laws are also reported and numerical simulations examine the stability of the Helmholtz power-law solitons. These simulations have led to the identification of a new propagation feature associated with spatial solitons in power-law media, constituting a new class of oscillatory solution

Advances in nonlinear optical materials and devices

The recent progress in the application of nonlinear techniques to extend the frequency of laser sources has come from the joint progress in laser sources and in nonlinear materials. A brief summary of the progress in diode pumped solid state lasers is followed by an overview of progress in nonlinear frequency extension by harmonic generation and parametric processes. Improved nonlinear materials including bulk crystals, quasiphasematched interactions, guided wave devices, and quantum well intersubband studies are discussed with the idea of identifying areas of future progress in nonlinear materials and devices

Nonlinear optical materials

Twenty different materials have been successfully deposited as Langmuir- Blodgett monolayer films. All exhibit second harmonic generation (SHG) when irradiated with laser light at 1064 nm. E-1-docosyl-4-{2-(4-dimethylami nophenyl)ethenyl}quinolinium bromide (C22H45QHBr) and E-1-docosyl-4-{2-(4-dimethy laminonaphthyl)ethenyl}quinolinium bromide (C22H45QNBr) have been deposited separately as multilayer films. They form Y-type structures when deposition is alternated with the material N-docosyl-4- methylquinolinium bromide. The nonlinear responses are quadratic up to 20 and 10 bilayers respectively and the response from the thick films is only 2 orders less than that produced by a Y-cut quartz plate. Similar results were obtained with C22H45QHBr when interleaved with 4,4'-dioctadecyl-3,5,3', 5'- tetra me thyldipyrrylmethenehydrobromide. Ellipsometry studies of the 10 bilayer film of C H45QNBr indicate that the structure is interdigitated. This explains the stability of the film which gave the same SH response up to 6 months after deposition. A 10 bilayer films has also been fabricated using E-1- docosyl-4-{2-(4-{2-(4-dimethylaminophenyl)ethenyl}benzyl)ethenyl}pyridinium bromide (C22H45PBHBr) alternated with E-1-docosy1-4-{2-(4-methylphenyl)ethenyl}pyridinium bromide (C22H45PT). E-1-octadecyl-4-{2-(4-methyloxyphenyl)ethenyl}pyridinium iodide and E-1- methyl-4-{2-(4-octadecyloxyphenyl)ethenyl}pyridinium iodide have been fabricated into monolayer films that are transparent at 1064 and 532 nm, therefore resonant enhancement does not contribute to their nonlinear response which is attributed solely to charge transfer in the molecule. Mixed solutions of E-1-octadecyl-4-{2-(4-methyloxyphenyl)ethenyl}pyridinium iodide and sodium octadecylsulphate (C1SH37OSO3 Na+) have been deposited as very stable monolayers. The nonlinear response from the mixed film offers a significant improvement upon the performance of the film containing pure hemicyanine. Novel zwitterionic materials have been fabricated as LB monolayers that also exhibit SHG

3D printing of optical materials: an investigation of the microscopic properties

3D printing technologies are currently enabling the fabrication of objects with complex architectures and tailored properties. In such framework, the production of 3D optical structures, which are typically based on optical transparent matrices, optionally doped with active molecular compounds and nanoparticles, is still limited by the poor uniformity of the printed structures. Both bulk inhomogeneities and surface roughness of the printed structures can negatively affect the propagation of light in 3D printed optical components. Here we investigate photopolymerization-based printing processes by laser confocal microscopy. The experimental method we developed allows the printing process to be investigated in-situ, with microscale spatial resolution, and in real-time. The modelling of the photo-polymerization kinetics allows the different polymerization regimes to be investigated and the influence of process variables to be rationalized. In addition, the origin of the factors limiting light propagation in printed materials are rationalized, with the aim of envisaging effective experimental strategies to improve optical properties of printed materials.Comment: 8 pages, 3 figure

Effects of simulated space radiation on selected optical materials

The effect of simulated Nimbus spacecraft orbital (1100 km, circular, and polar) radiation on wide bandpass glass filters, narrow bandpass thin film interference filters, and several fused silicas was determined by transmittance measurements over the 200 to 3400 nanom wavelength region. No changes were observed in the filters, which were shielded with fused silica during irradiation, after exposure to a 1-year equivalent orbital dose of electrons, nor in the fused silicas after the same electron exposure plus a 1-year equivalent dose of protons. Exposure to a 1/2-year equivalent dose of solar ultraviolet radiation caused a significant degradation in the transmittance of two ultraviolet-transmitting interference filters but had no effect on two colored glass filters that transmitted in the visible and near infrared regions. As a result of the ultraviolet exposure the fused silicas exhibited losses of several percent over the 200- to 300 nanom wavelength region