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

The detection and measurement of gas concentrations using the characteristic optical absorption of the gas species is important for both understanding and monitoring a variety of phenomena from industrial processes to environmental change. This study reviews the field, covering several individual gas detection techniques including non-dispersive infrared, spectrophotometry, tunable diode laser spectroscopy and photoacoustic spectroscopy. We present the basis for each technique, recent developments in methods and performance limitations. The technology available to support this field, in terms of key components such as light sources and gas cells, has advanced rapidly in recent years and we discuss these new developments. Finally, we present a performance comparison of different techniques, taking data reported over the preceding decade, and draw conclusions from this benchmarking.

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Optical gas sensing: a review

A review of optical limiting mechanisms and devices using organics, fullerenes, semiconductors and other materials

Discrete Solitons in Optics

A two-hand model is used to calculate the scaling and spectrum of the nondegenerate nonlinear absorption. From this, the bound electronic nonlinear refractive index n/sub 2/ is obtained using a Kramers-Kronig transformation. The authors include the effects of two-photon and Raman transitions and the AC Stark shift (virtual band blocking). The theoretical calculation for n/sub 2/ shows excellent agreement with measured values for a five-order-of-magnitude variation in the modulus of n/sub 2/ in semiconductors and wide-gap optical solids. Beam distortion methods were used to measure n/sub 2/ in semiconductors. The observations result in a comprehensive theory that allows a prediction of n/sub 2/ at wavelengths beneath the band edge, given only the bandgap energy and the linear index of refraction. Some consequences for all-optical switching are discussed, and a wavelength criterion for the observation of switching is derived. >

Dispersion of bound electron nonlinear refraction in solids

The dispersion relations for TE polarized waves guided by thin dielectric (planar integrated optics) films, surrounded on one or both sides by media with intensity-dependent refractive indexes, are solved numerically and interpreted. Comparisons are made between these nonlinear guided waves and the usual integrated optics modes associated with linear media. For media characterized by self-defocusing nonlinearities, increasing guided wave power leads to a decrease in the guided wave effective index and to mode cutoffs characterized either by finite or diverging total guided wave powers. For self-focusing media, the effective index increases with increasing power. New wave solutions are obtained with power thresholds and anomalous power-dependent field distributions. These characteristics are illustrated by numerical calculations for a specific material system and possible applications to optical devices are discussed.

Calculations of nonlinear TE waves guided by thin dielectric films bounded by nonlinear media

Laser Induced Processes in Molecules

A new type of electron-beam-addressed spatial light modulator has been demonstrated. It is based on the local tuning of an optothermal nonlinear interference filter by the scanned electron beam. Such an e-beam-tunable interference filter device should find applications in both display technology and optical data processing.

Electron-beam-tunable interference filter spatial light modulator.

This paper presents new results and reviews the latest state of research in all-optical nonlinear logic switches, amplifiers, and memories. Optical circuit elements that perform the logic functions of the electronic computer are described. Switching speed on a picosecond time scale, the availability of fast high bandwidth consistent communication, and the application of optical parallelism in free space optical wiring are some advantages of the optical computing elements.

Optical bistability, photonic logic, and optical computation.

An improved version of the selective chopper radiometer which has successfully flown for three years on the Nimbus 4 satellite has been built for the Nimbus 5 satellite which was launched in December 1972. The new instrument has 16 channels, eight of which observe emission from the 15 μm band of carbon dioxide for remote temperature sounding, two observe emission from water-vapour and ice clouds in the far infrared, one observes emission from low atmospheric water-vapour, three are in spectral regions where the atmosphere is substantially transparent, i.e. window regions, and two observe reflected sunlight from high clouds near to 2.7 μm in the near infrared. The horizontal resolution of the instrument is about 25 km and a complete set of measurements is made every 4 s. The design, construction and calibration of the instrument are described.

Stanley Desmond Smith

Papers

Calculations of nonlinear TE waves guided by thin dielectric films bounded by nonlinear media

Laser Induced Processes in Molecules

Electron-beam-tunable interference filter spatial light modulator.

Optical bistability, photonic logic, and optical computation.

Remote sounding of atmospheric temperature from satellites IV. The selective chopper radiometer for Nimbus 5