Abstract: The broadband semiconductor optical amplifier fabricated in accordance with the teachings of the present invention comprises first and second active semiconductor regions (50, 51) disposed in tandem with each other, and means for injecting current (I.sub.1,I.sub.2) into the first and second active semiconductor regions to provide gain distributions over wavelength regions in the two active semiconductor regions which partially overlap to form a combined gain distribution over a wider range of wavelengths. Anti-reflection coatings (54, 55) are disposed on the extreme ends of the combined structure. Tuneable wavelength selective amplification over the wider range is achieved in various embodiments by including a tunable optical bandpass filter (53) or by including various tunable auxiliary light guiding structures (115, 116; 140; or 450) to which and from which light power is coupled from and to the active semiconductor regions of the amplifier, respectively.

Abstract: Longitudinal mode coupling is used in an injection laser to achieve single longitudinal mode output. By imposing a to small amplitude sinusoidal signal to modulate the laser injection current, this coupling is provided by producing sidebands on the photon distributions of the longitudinal modes.

Abstract: An injection laser fabricated in accordance with the teachings of the present invention comprises a laser cavity having first and second active laser regions disposed in tandem therein, means for injecting current into the first and second active laser regions to provide gain distributions over wavelength regions in the two active laser regions which partially overlap to form a combined gain distribution over a range of wavelengths and means for providing wavelength within the range. In various embodiments of the present invention, the means for providing wavelength selective reflector or means for coupling energy out of the active regions. Moreover, the wavelength of the output radiation in various embodiments is determined by the values of the injected current density in the two active laser regions and the relative magnitudes of the loss at specific wavelengths.

Abstract: The present invention pertains to an injection laser which advantageously suppresses mode-partition-noise. The laser comprises a laser cavity with a gain or active material and means for providing a small amplitude wavelength selective loss. In one embodiment of the present invention the means for providing a small amplitude loss is a wavelength selective reflector.

Abstract: The present invention pertains to an injection laser which advantageously suppresses mode-partition-noise. The laser comprises a laser cavity with a gain or active material and means for providing a small amplitude wavelength selective loss. In one embodiment of the present invention the means for providing a small amplitude loss is a wavelength selective reflector.

Abstract: The present invention pertains to an injection laser which advantageously reduces main mode output power fluctuation. The laser comprises a laser cavity having an active material joined at one end to a passive waveguide. The passive waveguide has a length which is equal to or greater than the length of the active material and an index of refraction which is substantially equal to that of the active material to prevent multicavity interference. In preferred embodiments of the present invention, the passive material is fabricated from a semiconductor material having a bandgap which is larger in energy than the energy of a photon in the laser radiation.

Abstract: An active tap for use in an optical multiple access network is disclosed. The tap comprises a semiconductor substrate on which the electronics associated with an active parallel path are fully integrated. These include optical detectors, amplifiers and light emitters formed using standard semiconductor fabrication techniques. A section of fiber, incorporated as an integral part of the tap structure, is provided with a pair of longitudinally spaced discontinuities for deflecting a portion of the incident signal onto the detector and for redirecting the output from the light emitter along the through-path. Alternatively, the tap substrate can be provided with a groove for receiving a fiber segment located anywhere along the distribution network.

Abstract: Two-dimensional semiconductor chips are stacked to form a three-dimensional array in which coupling between chips is effected optically. This permits the use of smaller chips, with a corresponding higher yield, and serves to reduce the chip area required for interconnecting leads. It also reduces the internal interconnection path lengths which, at present, limit the speed of operation.

Abstract: A new transmission system configuration is disclosed which takes advantage of the special properties of lightwave devices and the extensive availability of frequency space on optical fibers. The system employs a combination of time and frequency multiplexing at the transmitter, and frequency demultiplexing at the receiver. An advantageous result of combining time and frequency multiplexing is to relax the tolerance requirements on filters at the transmitter. A further advantage is to minimize the effects of mode dispersion introduced by the fiber.

Abstract: An electro-optic integrated circuit is disclosed wherein the long electrical connections normally present on a large scale integrated circuit are replaced by an optical waveguide layer. A plurality of epitaxial layers are grown on a single substrate and at least three of the plurality of epitaxial layers are grown with bandgaps that are suitable for optical sources, detectors and waveguiding. These primary layers are separated from each other by a barrier layer having a bandgap greater than either of the adjacent primary layers. Two of the layers adjacent to the substrate are grown to accommodate electrical devices that can be used to couple electrical signals to the optical source layers and to amplify electrical signals provided by the optical detection layer.

Abstract: Optical fibers having enhanced mode coupling produced by an asymmetric refractive index profile that varies periodically along the length of the fiber are described. The prescribed variations are obtained by means of a fabrication process that includes periodically varying the source of at least one of the fiber materials in a direction transverse to the fiber-drawing direction. This transverse periodicity is translated into the desired longitudinal periodicity along the fiber by the fiber-drawing process.

Abstract: Transmission configurations are described for providing usable service despite the complete interruption of one or more of several transmission links. This is accomplished by encoding (11) the information content of each of a plurality of input signals (S.sub.1, S.sub.2 . . . S.sub.n) into a multiplicity of encoded signals (s.sub.1, s.sub.2 . . . s.sub.m) for simultaneous transmission along a multiplicity of transmission links (13.1, 13.2 . . . 13.m). At the receiver, a decoder (12) recovers the individual input signals. By accepting temporarily either a bandwidth or a signal-to-noise reduction, service is continued even though one or more of the transmission links fails.

Abstract: A method of fabricating an optical fiber having an asymmetric refractive index profile that varies periodically along the length of the fiber is described. The prescribed variations are obtained by means of a fabrication process that includes periodically varying the source of at least one of the fiber materials in a direction transverse to the fiber-drawing direction. This transverse periodicity is translated into the desired longitudinal periodicity along the fiber by the fiber-drawing process.

Abstract: The separate steps of forming an optical fiber preform and then drawing the fiber are combined into an essentially simultaneous process wherein a "stub" preform (18) is formed by means of the so-called "vapor-phase axial-deposition" method while the fiber (17) is simultaneously drawn from the end of the stub that is opposite to the end upon which the particulate matter (14, 15) is being deposited.

Abstract: A terminating portion of an optical fiber waveguide having a polished beveled end is laterally disposed directly on the light-emitting surface of a light-emitting diode (LED). The light power coupled into the fiber consists of two components: the light power directly coupled into the fiber all along the region of contact between the fiber and the light-emitting surface; and the light power reflected by the beveled end and directed along the fiber axis.