Abstract: An improved optical communication system is provided, the system particularly suited for so-called short-haul applications, e.g., applications involving transmission over distances less than 100 km, such as metro applications. The system uses an external cavity laser made up of a gain medium that comprises an active region, a beam expanding region, and an antireflective layer, an optical waveguide located adjacent the gain medium, and a Bragg grating integral with or coupled to the optical waveguide. The medium and the optical waveguide, due to the beam expanding region, exhibit a coupling efficiency of at least 40%, advantageously at least 50%, even in the absence of coupling optics, and the laser is configured and operated to emit at least two modes.

Abstract: An improved optical communication system is provided, the system particularly suited for so-called short-haul applications, e.g., applications involving transmission over distances less than 100 km, such as metro applications. The system uses an external cavity laser made up of a gain medium that comprises an active region, a beam expanding region, and an antireflective layer, an optical waveguide located adjacent the gain medium, and a Bragg grating integral with or coupled to the optical waveguide. The medium and the optical waveguide, due to the beam expanding region, exhibit a coupling efficiency of at least 40%, advantageously at least 50%, even in the absence of coupling optics, and the laser is configured and operated to emit at least two modes.

Abstract: A semiconductor laser includes first and second laser cavities. The first and second cavities share a common optical gain medium and lase at different wavelengths.

Abstract: A semiconductor laser includes first and second laser cavities. The first and second cavities share a common optical gain medium and lase at different wavelengths.

Abstract: High storage densities using a holographic system are achievable using a stratified medium while maintaining a relatively high selectivity upon reconstruction of the stored images. Such combination of high density and high selectivity is achievable by employing a stratified medium and a recording process where selectivity does not vary with recording thickness.

Abstract: An improved process for holography is provided, in which the reference beam used for storage and readout has a correlated phase content. In particular, it was found that reference beams having random phase content limited the attainable storage density and the accuracy of readout of stored holograms due to uncontrolled fluctuations in the correlation selectivity. By contrast, a reference beam having correlated phase content provides accurate shift selectivity, the ability to tailor the reference beam spectrum to minimize crosstalk between neighboring holograms, and mitigation of limitations inherent in the holographic system or holographic medium. Improved storage density and readout accuracy are thereby attained.

Abstract: A system and method for controlling the selectivity function in a holographic memory system that permits more rapid location and retrieval of holographically stored data. The system and method direct a reference beam through a filter such as, for example, an aperture, to bandwidth limit the beam before the beam illuminates a holographic optical element having stored therein a hologram of a reference beam.

Abstract: In accordance with the invention, an improved optical communication system employs light-generating devices comprising a phonon-tuned crystal alloy host doped with an optically active atom. In one embodiment, the crystal alloy host and optically active atom respectively comprise spinel and nickel. The spinel material is typically a solid solution between magnesium aluminate and magnesium gallate.

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: 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: Holograms within an array are recorded and/or read out by use of a reference/read out beam produced by illumination of a phase mask.

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.