Abstract: A reconfigurable ring architecture for RF transport over fibers which eliminates the need for multiple pairs of fibers to serve multiple microcells and the need for backup communications lines as a result of system failure due to a fiber break. The ring architecture has a plurality of remote units which are interconnected to a host unit in a serial fashion. The host unit transmits signals to the plurality of remote units and receives signals from the plurality of remote units. Each of the remote units having photodetectors for receiving the transmitted signals and an antenna/transmitter for receiving other signals from another source; a splitter for splitting the transmitted signals into two parts, one part of the signals being output from the remote unit and the other part of the signals being transferred to adjacent remote units and then back to the host unit; and a transmitter for transferring the other signals from the remote unit to adjacent remote units and then back to the host unit.

Abstract: A semiconductor optical amplifier with a high speed photodetector acting as an optical tap is disclosed. The device functions simultaneously as an in-line optical amplifier and as a high-speed photodetector tap. An in-line an optical amplifier is combined with a waveguiding, high speed (low capacitance) reverse-biased photodetector that absorbs only a percentage of the amplified signal, allowing the remainder to pass through without distortion.

Abstract: An optical preamplifier includes a semiconductor optical amplifier monolithically integrated with an optical detector and electrically isolated from the detector by an isolation region. The isolation region consists of a low-loss, preferably transparent, insulating material whose index of refraction is matched to at least the refractive index of the amplifier, leading to reduced facet reflectivity at the amplifier output facet. Alternative device structures may include a waveguiding layer in the isolation region, a grating integrated with or following the optical amplifier, and a tuning region positioned between the amplifier and isolation region for filtering spontaneous emission.

Abstract: A monolithically integrated optical preamplifier comprises an amplifying region, an optical detection region for detecting amplified light, and an optically transparent and electrically insulating isolation region interposed between the amplifying and optical detection regions. The amplifying region achieves reduced facet reflectivity by being designed to have a large spot size, single-traverse mode waveguide amplifier oriented at an angle with respect to a crystal plane through the preamplifier. The isolation region is preferably an air gap.

Abstract: A method for optically coupling multiple single-mode optical fibers to a single packaged optoelectronic array device uses a single graded index lens to magnify the images of the active semi-conductor elements and to expand the spacing between their light beams. These separated magnified light beams then coupled to an associated array of uptapered optical fibers. Simultaneous alignment is possible because the location of the semiconductor array beams can be known with high precision relative to the central beam in the array. A lens with known magnification is first positioned relative to the central beam. Alignment to this central beam automatically aligns other optical fibers held collectively in a fixture engineered with the geometry set by the known magnification of the lens. The coupling of single-mode optical fiber to two-dimensional semiconductor surface arrays utilizes the projected and magnified beams of the array which replicate the precise placement of the array elements.

Abstract: A method of optically coupling an optoelectronic device having a photoactive element to an uptapered single-mode optical fiber which connects said optoelectronic device to an external device includes securing a graded index lens to a substrate carrier within a housing at a distance calculated to provide a known magnification of a light beam emanating from said element, and further includes mechanically positioning and actively aligning the fiber to said magnified light beam to achieve optimal optical coupling to said optoelectronic device. The location of a plurality of reference marks and surfaces are determined such that the photoactive element, the lens and the uptapered end of the single-mode optical fiber may be positioned with respect to these references for precise optical coupling using an active alignment for final adjustments. The reference surfaces include a pedestal for the laser and a plurality of stops for the lens integrally formed with the substrate.

Abstract: A package for an optoelectronic device, such as a laser, having a photo-active element optically coupled to an uptapered single-mode optical fiber which connects said optoelectronic array to an external device includes a housing having a solderable substrate to which the device is secured, a graded index lens also secured to said substrate at a distance calculated to provide a known magnification of light beam emanating from said laser and an uptapered single-mode optical fiber mechanically positioned and actively aligned to said mangified light beam to achieve optimal optical coupling to said optoelectronic device. The package includes a plurality of reference marks and surfaces such that the laser, the lens and the uptapered end of a single-mode optical fiber may be positioned for precise optical coupling using an active alignment for final adjustments. The reference surfaces include a pedestal for the laser and a plurality of stops for the lens integrally formed with the substrate.

Abstract: A package for an optoelectronic array device having an array of n active elements optically coupled to an array of n single-mode optical fibers which connect said optoelectronic array to an external device includes a housing having a solderable substrate to which the array device is secured, a graded index lens also secured to said array at a distance calculated to provide a known magnification of light beams emanating from said array and n uptapered single-mode optical fibers actively aligned to said magnified light beams to achieve optimal optical coupling to said optoelectronic array. The package optionally includes a multifiber holder having precisely calculated spacing based on the spacing of said active elements which are usually semiconductor lasers and the magnification of said lens. For a two-dimensional surface array, the package includes a mandrel to position the uptapered optical fibers.

Abstract: A novel method for reducing the facet reflectivities of semiconductor light sources and amplifiers concerns the use of a bulk (non-waveguiding) index-matched regrown end cap region at both of the major facet surfaces of the amplifier. The amplifier has a tilted stripe geometry which, in combination with the end cap regions, enable the amplifier to reproducibly achieve facet reflectivities of less than 10.sup.-5 while avoiding a facet coating step. The improved optical amplifier is more amenable to mass production and less sensitive to both wavelength and polarization.