4. Survey of Novel Multiphoton Active Materials 1257 4.1. Multiphoton Absorbing Systems 1257 4.2. Organic Molecules 1257 4.3. Organic Liquids and Liquid Crystals 1259 4.4. Conjugated Polymers 1259 4.4.1. Polydiacetylenes 1261 4.4.2. Polyphenylenevinylenes (PPVs) 1261 4.4.3. Polythiophenes 1263 4.4.4. Other Conjugated Polymers 1265 4.4.5. Dendrimers 1265 4.4.6. Hyperbranched Polymers 1267 4.5. Fullerenes 1267 4.6. Coordination and Organometallic Compounds 1271 4.6.1. Metal Dithiolenes 1271 4.6.2. Pyridine-Based Multidentate Ligands 1272 4.6.3. Other Transition-Metal Complexes 1273 4.6.4. Lanthanide Complexes 1275 4.6.5. Ferrocene Derivatives 1275 4.6.6. Alkynylruthenium Complexes 1279 4.6.7. Platinum Acetylides 1279 4.7. Porphyrins and Metallophophyrins 1279 4.8. Nanoparticles 1281 4.9. Biomolecules and Derivatives 1282 5. Nonlinear Optical Characterizations of Multiphoton Active Materials 1282

Multiphoton Absorbing Materials : Molecular Designs, Characterizations, and Applications

Concepts for the incorporation of inorganic building blocks into organic polymers on a nanoscale

Two-photon fluorescence microscopy is one of the most important recent inventions in biological imaging. This technology enables noninvasive study of biological specimens in three dimensions with submicrometer resolution. Two-photon excitation of fluorophores results from the simultaneous absorption of two photons. This excitation process has a number of unique advantages, such as reduced specimen photodamage and enhanced penetration depth. It also produces higher-contrast images and is a novel method to trigger localized photochemical reactions. Two-photon microscopy continues to find an increasing number of applications in biology and medicine.

Two-Photon Excitation Fluorescence Microscopy

Large two-photon absorptivities are reported for symmetrical bis-donor stilbene derivatives with dialkylamino or diphenylamino groups. These molecules exhibit strong optical limiting of nanosecond pulses over a broad spectral range in the visible. Relative to bis(di-n-butylamino)stilbene, bis(diphenylamino)stilbene exhibits a 90-nm red shift of its optical limiting band but only a minimal shift of ~13 nm of its lowest one-photon electronic absorption band. Mixtures of these compounds offer an unprecedented combination of broad optical limiting bandwidth and high linear transparency.

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Two-photon absorption and broadband optical limiting with bis-donor stilbenes.

Functional organic materials with enhanced two-photon absorption lead to new technologies in the fields of chemistry, biology, and photonics. In this article we review experimental and theoretical methodologies allowing detailed investigation and analysis of two-photon absorption properties of organic chromophores. This includes femtosecond two-photon excited fluorescence experimental setups and quantum-chemical methodologies based on time-dependent density functional theory. We thoroughly analyze physical phenomena and trends leading to large twophoton absorption responses of a few series of model chromophores focusing on the effects of symmetric and asymmetric donor/acceptor substitution and branching.

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Enhanced two-photon absorption of organic chromophores: theoretical and experimental assessments ∗∗

Efficient, two-photon pumped green upconverted cavity lasing in a new dye

Sol-gel-processed organic-inorganic hybrid materials combine the merits of inorganic glass and organic molecules, and are therefore a class of materials with good potential for photonics. In this review, two approaches which have shown promising results for producing useful materials for photonics are described: (i) a novel way to fabricate organically doped, multiphasic nanostructured composite monoliths and (ii) a method of fabrication of organically doped, sol-gel-derived optical fibers. For each approach, the preparation process is presented, together with selected applications such as multidye solid-state tunable laser, multiphasic optical power limiter, a micron-scale chemical-sensing and biosensing fibers and solid-state dye-doped fiber lasers.

Novel, Organically Doped, Sol–Gel‐Derived Materials for Photonics: Multiphasic Nanostructured Composite Monoliths and Optical Fibers

In this paper we present a new concept to control the energy transfer between two components using novel multiphasic nanostructured composites. The example studied here consists of two lasing dyes (Rhodamine-6G and trans-4-[p-(N-ethyl-N-(hydroxyethyl)amino)phenylstyryl]-N-(hydroxyethyl)pyridinium iodide (ASPI)), each of which resides in two different phases of a multiphasic composite. The energy transfer between these two phases was studied and found to be insignificant. Therefore, this composite exhibited lasing from both dyes. The multiphasic matrix was tunable through the range of both dyes from 560 to 610 nm with an efficiency of ∼7%. The lasing properties of this lasing media were studied compared to reference dye solutions. In the solution state a mixture dye solution exhibited complete quenching of one of the dyes (Rhodamine-6G). The quenching mechanism in the solution state and its lack in the solid state matrix is proposed. In addition, the new laser dye, ASPI, has been characterized by its linea...

Multiphasic nanostructured composite : multi-dye tunable solid state laser

New laser medium: dye-doped sol-gel fiber

Nanocomposite materials for application in photonics were developed by sol-gel processing and reverse micellar microemulsion techniques The capability of incorporating many materials with different functional properties in sol-gel processed glass matrices has been explored in making these materials The large pore volume fraction and the enormous surface area of the sol-gel glasses enables one to introduce many materials in a phase separated fashion, where the phase separation is in the nanometer range It is possible to introduce an active material on to the pore surface by solution infiltration and subsequent removal of the solvent, then filling the pores with a monomer containing another active material, and polymerizing inside the pores Using this approach the authors have developed composite materials for optical power limiting applications at different wavelengths and a tunable solid state dye lasing medium Optically transparent polyimide:TiO{sub 2} composite waveguide materials were prepared by the dispersion of nano-sized TiO{sub 2} particles into a polyimide matrix The particles were produced through reverse micelles using the sol-gel method, and were incorporated into the fluorinated polyimide solution A polyimide:TiO{sub 2} (4 wt%) composite waveguide was produced from the solution Since the particle size is so small, no noticeable scattering loss was observedmore » The measured optical propagation loss at 633 nm was 14 dB/cm, which is equivalent to that of the pure polyimide The refractive index was increased from 1550 to 1560 by the incorporation of TiO{sub 2}« less

Gary Ruland

Papers

Efficient, two-photon pumped green upconverted cavity lasing in a new dye

Novel, Organically Doped, Sol–Gel‐Derived Materials for Photonics: Multiphasic Nanostructured Composite Monoliths and Optical Fibers

Multiphasic nanostructured composite : multi-dye tunable solid state laser

New laser medium: dye-doped sol-gel fiber

Nanostructured materials for photonics