Abstract: A silica-water dispersion suitable for use as a sol for sol-gel fabrication is produced from a silica-water mixture with addition of alkaline agent. The agent functions to increase viscosity so as to improve dispersing efficiency during shear mixing.

Abstract: Pump depletion modulation crosstalk between WDM channels in Raman amplified systems is virtually eliminated by exclusive use of backward pumping.

Abstract: A thick holographic recording medium suitable for use in multiplex holography is prepared from a solution of a bi-functional oligomer and a mono-functional monomer. Precuring, possibly at the same radiation wavelength used for recording, cross-links the oligomer, thereby creating a host for the recording monomer.

Abstract: A fiber suitable for use in high capacity optical fiber network operative with wavelength division multiplexing. Contemplated systems can utilize span distances in excess of 100 km, signal amplification within spans, and provide plural multiplexed channels operative at multiple gigabits per second.

Abstract: A cladding-pumped fiber structure, suitable for use as a laser, provides for efficient clad-to-core energy transfer. The outside interface of the pump-clad is constructed from a rod-shaped preform by local melt-displacement using an open flame.

Abstract: Selection of individual holograms during read-out of a multiplexed array depends upon varying relative position of the recording medium in the direction orthogonal to the medium surface.

Abstract: Cracking in thin sheets of sol-gel-produced material is avoided by use of a support liquid during gelation and drying. Silica glass, as well as other glass and ceramic bodies, is contemplated.

Abstract: Simultaneous dense WDM operation in both the 1310 nm and 1550 nm transparency windows of silica-based optical fiber, is enabled by a fiber design providing for nulled dispersion within a critically positioned wavelength range. Design provides for values of dispersion in both windows sufficiently low for desired per-channel bit rate, and, at the same time, sufficiently high to maintain effects of non-linear dispersion within tolerable limits for WDM operation. Fiber fabrication and system design are described.

Abstract: Use of an aperture in the reconstructed beam in reconstruction of multiple holograms increases selectivity beyond that realizable by spatial multiplexing so as to permit differentiation of overlapping images. "Aperturization" is suitably used for differentiation in the y-direction in shift holography, depending on Bragg selection in the x-direction.

Abstract: A module, for upgrading optical fiber systems, includes an appropriate length of Dispersion Compensating Fiber (DCF) for nulling chromatic dispersion, together with a pump, which uses Stimulated Raman Scattering for amplifying signal in the DCF, thereby compensating for power loss associated with the DCF.

Abstract: A thick holographic recording medium suitable for use in multiplex holography is prepared from a solution of a bi-functional oligomer and a mono-functional monomer. Precuring, possibly at the same radiation wavelength used for recording, cross-links the oligomer, thereby creating a host for the recording monomer.

Abstract: A cladding-pumped fiber structure, suitable for use as a laser, provides for efficient clad-to-core energy transfer. The outside interface of the pump-clad is constructed from a rod-shaped preform by local melt-displacement using an open flame.

Abstract: A significant part of signal-to-noise degradation in WDM optical fiber communications, due to Raman crosstalk, is found to be deterministic in nature. Shaping of amplifier output to offset depletion of high frequency channels improves signal capacity by an order of magnitude.

Abstract: A high capacity optical fiber network operative with wavelength division multiplexing. Contemplated systems can utilize span distances in excess of 100 km, signal amplification within spans, and provide plural multiplexed channels operative at multiple gigabits per second.

Abstract: Bit error rate in holographic storage/reconstruction is reduced by 2-dimensionally dispersing symbols constituting codewords so that no two codeword-common symbols occupy a single row or column on the SLM display.

Abstract: Bit error rate of an output data stream, reconstructed from a holographic recording, is reduced by reducing the length of same-state pixels on the spatial light modulator.

Abstract: A system for high density holographic storage announced by Cal Tech is improved. The basic Cal Tech system records successive holograms by physically shifting the recording medium relative to the paired reference and signal beams. By depending on Bragg selectivity, successive holograms may be overlapped and still differentiated in the direction of overlap--in the "x-direction". The claimed system improves storage density by tilting the holographic plane to introduce a Bragg component in the y-direction, thereby enabling differentiation of overlapping holograms in that direction as well.

Abstract: WDM optical fiber communications entails bidirectional transmission with at least two WDM channels in opposite transmission directions in a single fiber. As compared with unidirectional transmission, a number of capacity-limiting considerations are relaxed. Operation using in-ground dispersion-shifted fiber permits system capacities of conventional unidirectional WDM.

Abstract: 1.times.2 and more complex switching operations use routing corresponding with guides produced by heating with a laterally-homogeneous layer. Strip heaters, in contact with a silica-based sandwich structure, thermally increase refractive index to define laterally-constrained cores within the center layer.

Abstract: Through-the-lens alignment during deep UV lithographic processing in the manufacture of VLSI is accomplished without shifting the mask or wafer from the exposure position. Introduction and extraction of alignment light of actinic wavelength depends on beam routing due to diffraction from an interference grating. The path of alignment light is within the focusing system but does not impinge on the focused pattern.