A new type of metallic electromagnetic structure has been developed that is characterized by having high surface impedance. Although it is made of continuous metal, and conducts dc currents, it does not conduct ac currents within a forbidden frequency band. Unlike normal conductors, this new surface does not support propagating surface waves, and its image currents are not phase reversed. The geometry is analogous to a corrugated metal surface in which the corrugations have been folded up into lumped-circuit elements, and distributed in a two-dimensional lattice. The surface can be described using solid-state band theory concepts, even though the periodicity is much less than the free-space wavelength. This unique material is applicable to a variety of electromagnetic problems, including new kinds of low-profile antennas.

Development in the WDM technologies has made multi-wavelength optical sources and components available. By combining WDM mux-demux and fast electro-optic switches, a fast configurable WDM add-drop filter can be obtained. This enables using WDM with TDM in a way that each TDM time slot is also wavelength multiplexed. Hence introducing a second dimension for switching in addition to the time dimension. This also alleviates the demanding requirement on TDM as the switching throughput increases. The number of channels that can be supported in a WDM/TDM hybrid switching system is the product of the number of time slots and the number of available wavelengths. We have done preliminary analysis on the system throughput. We will present implementation considerations of the above described systems, the give the comparison on the throughput and security sides.

Summary form only given.Optical single sideband modulation has received great interest as a way to reduce the dispersion penalty of analog fiber-optic systems. We propose and demonstrate a tandem single sideband fiber-optic link, which uses a dual-electrode Mach-Zehnder modulator to place different information in each of the two sidebands, thus doubling the bandwidth efficiency.

The bandwidth demanded for Internet traffic has been constantly growing in response to more bandwidth hungry applications such as high-resolution motion picture transmission. An optical fiber has about 10 tera-bits per second (Tbps) available bandwidth and is the ideal medium to link tomorrow's bandwidth hungry applications. The equipment purchased under this grant has permitted UCLA to purchase a number of broad-band optical components, including especially some unique code division multiplexing filters that permitted us to demonstrate optical code division multiplexing of a multi-wavelength signal source.

Nonmethane hydrocarbons are ubiquitous trace atmospheric constituents yet they control the oxidation capacity of the atmosphere. Both anthropogenic and biogenic processes contribute to the release of hydrocarbons to the atmosphere. In this manuscript, the state of the science concerning biosynthesis, transport, and chemical transformation of hydrocarbons emitted by the terrestrial biosphere is reviewed. In particular, the focus is on isoprene, monoterpenes, and oxygenated hydrocarbons. The generated science during the last 10 years is reviewed to explain and quantify hydrocarbon emissions from vegetation and to discern impacts of biogenic hydrocarbons on local and regional atmospheric chemistry. Furthermore, the physiological and environmental processes controlling biosynthesis and production of hydrocarbon compounds are reported on. Many advances have been made on measurement and modeling approaches developed to quantify hydrocarbon emissions from leaves and forest ecosystems. A synthesis of the atmospheric chemistry of biogenic hydrocarbons and their role in the formation of oxidants and aerosols is presented. The integration of biogenic hydrocarbon kinetics and atmospheric physics into mathematical modeling systems is examined to assess the contribution of biogenic hydrocarbons to the formation of oxidants and aerosols, thereby allowing us to study their impacts on the earth's climate system and to develop strategies to reduce oxidant precursors in affected regions.

The objective of this program is to make infrared pigments whose emissivity can be controlled. The principal approach we have taken is to make 3-dimensionally microstructured metallodielectric materials by two-photon lithography in photoresist, and back-filling with metals. In this program we demonstrated that we can quickly and efficiency fabricate 3<1 microstructures in photoresist using a diode pumped Ti-sapphire modelocked laser in combination with a mechanical scanning technology. Metal back-filling of copper into porous membranes was accomplished using electrodeposition methods and complementary fundamental studies were able to establish some of the details of this metallization process. Initial results using self-assembly methods for metallization were also obtained. Another approach for producing 3<1 metallo-dielectric structures, based on the direct writing of silver structures by two-photon processes, was also demonstrated. In addition to experimental work, this program included computational activities. An analysis of the resolution limits of two-photon lithography showed that a doubling of resolution was possible. Other studies in this program included the design of frequency selective grid structures and an analysis showing that 1-d interference filters can be used to achieve a broad reflection spectrum.

We have found experimental conditions for the growth of n <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">+</sup> -SIPOS:p-Si heterojunction emitters with forward saturation current J <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> = 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-14</sup> Amps/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> or equivalently "emitter Gummel number" G <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">e</inf> = 3.3 × 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">15</sup> s/cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sup> . This outstanding figure of merit seems to rely upon the presence of a thin interfacial oxide between the SIPOS and the crystalline silicon. We invoke a model in which majority-carrier (electron) contact is made by microcrystalline grains which protrude into the interfacial oxide but minority-carrier (hole) recombination is inhibited by the small fractional area coverage of such contacts. The result is an emitter structure which is robust and relatively insensitive to variations in processing conditions.

The coincidence in excitation energy between surface plasmons on silver and the GaN band gap is exploited to couple the semiconductor spontaneous emission into the metal surface plasmons. A 3-nm InGaN/GaN quantum well (QW) is positioned 12 nm from an 8-nm silver layer, well within the surface plasmon fringing field depth. A spectrally sharp photoluminescence dip, by a factor \ensuremath{\approx}55, indicates that electron-hole energy is being rapidly transferred to plasmon excitation, due to the spatial overlap between the semiconductor QW and the surface plasmon electric field. Thus, spontaneous emission into surface plasmons is \ensuremath{\approx}55 times faster than normal spontaneous emission from InGaN quantum wells. If efficient antenna structures can be incorporated into the metal film, there could be a corresponding increase in external light emission efficiency.

A high-impedance electromagnetic surface is a new type of metallic structure exhibiting high surface impedance and the suppression of propagating surface currents at a particular frequency band. We experimentally characterize such a high-impedance surface designed near 2.4 GHz. We describe an antenna built on such a surface, integrated into a printed circuit board that was designed for the form factor of a portable handset. Measurement shows high radiation efficiency near 2.4 GHz.