At&t Bell Laboratories

Bell Communications Research, Inc.

Bell Telephone Laboratories

Robert N Thurston

Gary D Boyd

Julian Cheng

Arie Shahar

Elyahou Kapon

Jonathan P Heritage

Robert B Meyer

Peter J Delfyett, Jr

Eugene W Chase

For use, e.g., in the compensation of frequency dispersion in the course of transmission of an optical signal, a pulse-shaping device is provided with a suitably shaped nonplanar mirror (16). When spatially spread-out frequency components--produced, e.g., by a grating (14)--are reflected from such mirror, a frequency-dependent phase shift is introduced; for example, such phase shift may be a third-order function of frequency. Upon recombination of frequencies, a shaped pulse is obtained. Furthermore, third-order compensation can be used to compress amplified light pulses, e.g. as produced by a semiconductor gain medium (80, 81).

Optical pulse-shaping device and method, and optical communications

A tapered single-mode rib waveguide for which only laterally patterning is required. A sublayer is disposed between the low-index substrate and the high-index rib and has an intermediate index. Preferably a thin buffer layer of very low refractive index is disposed between the rib and the sublayer. The widths of the rib are chosen so that in a wide portion the optical power of the single-mode is concentrated in the rib or buffer layer but in a narrow portion the optical power is concentrated in the sublayer or substrate and additionally has a wide lateral distribution. A similar effect can be obtained by tapering an upper rib disposed on top of an untapered lower rib.

Tapered rib waveguides

A bistable nematic liquid crystal display cell is switched between topologically equivalent, asymmetric horizontal states. Switching is initiated by application of a directional, symmetry breaking field such as a transverse magnetic field. An electric potential is then applied across the cell to complete the switching cycle and maintain the state. The cell includes upper and lower parallel substrates, upper and lower topographically textured tilt alignment surfaces on the corresponding substrates, and nematic liquid crystal material between the substrates. In an active region of the cell, the tilt alignment surfaces form an equal reverse tilt boundary condition. In an isolation region surrounding the active region of the cell, the tilt alignment surfaces form a parallel tilt boundary condition.

Nematic liquid crystal storage display device

A bistable nematic liquid crystal display cell is electrically switched between topologically equivalent, asymmetric horizontal states. The cell includes upper and lower parallel substrates, upper and lower topographically textured tilt alignment surfaces on the corresponding substrates, and nematic liquid crystal material between the substrates. In an active region of the cell, the tilt alignment surfaces form an unequal reverse tilt boundary condition. In an isolation region surrounding the active region of the cell, the tilt alignment surfaces are formed to avoid the reverse tilt boundary condition.

Elastic waves are propagated in a waveguide comprising an elongate central core region and an outer cladding region, the cladding region having a larger bulk shear elastic wave velocity than the core region. Transducers at respective ends of the waveguide couple between electrical signals and 'shear' mode elastic waves in which the principal particle displacement is substantially perpendicular to a plane passing through the central longitudinal axis of the core region. The cladding region is sufficiently thick to ensure that the particle displacement profile is substantially zero at its outer surface. The waveguide is mounted in a medium suitable to mechanically support it and to protect it against external mechanical shock.

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Colts Neck, NJ, United States of America

Robert N Thurston