Much of the technology of our era is based on the SiO2/Si amorphous/crystalline heterojunction interface. Now it appears that As2S3/GaAs amorphous/crystalline heterojunctions show some technological promise. We have found that properly prepared As2S3/GaAs interfaces can have reasonably good electronic quality. The interfacial recombination velocity is ≊15 000 cm/s at flat band, which results in a ∼100-fold reduction of perimeter recombination currents in p-n junction mesas. This can be important on heterojunction transistor emitter-base perimeters, solar cell and light-emitting diode perimeters, and for reducing mirror facet recombination in semiconductor lasers.

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.

We present an optical tandem single-sideband receiver that enables the detection of signals having different information in the two sidebands of the same optical carrier. The technique relies on the use of a dual-electrode Mach-Zehnder modulator and achieves heterodyne detection without the use of an optical local oscillator. Sharp filtering requirements are met in the electrical domain, eliminating the need for wasteful guardbands.

We describe how quantum information may be transferred from photon polarization to electron spin in a semiconductor device. The transfer of quantum information relies on selection rules for optical transitions, such that two superposed photon polarizations excite two superposed spin states. Entanglement of the electron spin state with the spin state of the remaining hole is prevented by using a single, non-degenerate initial valence band. The degeneracy of the valence band is lifted by the combination of strain and a static magnetic field. We give a detailed description of a semiconductor structure that transfers photon polarization to electron spin coherently, and allows electron spins to be stored and to be made available for quantum information processing.

Summary form only given. Two-photon exposure can be advantageous for the improving of spatial resolution of an image. Two-photon exposure uses the square of the pulse intensity profile, resulting in decrease of the spot size. More important, it has been shown recently, that multi-frequency beams can interfere with each other to produce a doubling of spatial resolution (although at 2:1 pedestal) if the media exposure is due to two-photon. We performed our experiments using Kodak commercial film.

A new type of metallic electromagnetic structure has been developed that is characterized by having high surface impedance. 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 2D lattice. 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. Furthermore, image currents induced in the surface are not phase reversed as they are on a flat metal surface.

We present an optical tandem single sideband receiver that eliminates the need for guardbands between adjacent WDM channels, while also receiving signals that have different data on the two sidebands of the same optical carrier.

Ultrathin metallic films have an interesting electromagnetic behavior as the frequency of the incident field is varied over several orders of magnitude, because of the dramatic dispersion exhibited by the metal permittivity. We study a finite multilayer of periodically placed planar conducting films for frequencies varying from the dc limit to the far ultraviolet. We provide the optimized reflectivity and transmittivity of the system for the various frequency regimes involved. Further, we produce the dispersion diagrams of the corresponding photonic bandgap structures, which clearly show the transition of the system from a metallic (low frequencies) to a dielectric (optical frequencies) behavior. In addition, simple design formulas for maximum reflectivity of finite film number N are presented in terms of film thickness and film spacing in each of the representative frequency ranges.

We present a systematic study of the infrared multiphoton excitation and dissociation of several polyatomic molecules. The molecules range in size from SO2, with three vibrational modes, to C3F7I, with 27. A gradual transition occurs from intensity dependent excitation, characteristic of a sparse density of vibrational states in small molecules, to a fluence dominated absorption characteristic of a quasicontinuum of vibrational states in large, heavy molecules. Molecules with ten or more atoms showed no intensity dependence under pulsed CO2 laser excitation at a fixed energy fluence. For a molecule to have a high probability of dissociation under realizable conditions of laser intensity and fluence, quasicontinuum region excitation must dominate. All molecules appeared to have statistically coupled vibrational modes at high levels of vibrational energy.

In the context of a proposed design of a solid-state receiver for quantum communications, we consider the Zeeman splitting of the light-hole states in strained cubic heterostructures with an in-plane external magnetic field. The choice of interband optical transitions that allows coherent transfer of photon polarization to electron spin suggests that the magnitude of corresponding g factor component will be a critically important quantity for the success of such devices. Our approach allows a straightforward calculation of this parameter and incorporates the quantum confinement, heterolayers composition, and strain effects on the g factor.