Abstract: A data packet transport arrangement includes a tag-based packet multiplexer and a tag-based packet demultiplexer, that utilizes an identification tag to identify packets to each of the N input channels so as to provide a logical transport channel for each of the N channels through the packet transport arrangement. The data transport arrangement thereby allows aggregating multiple communications channels into a higher bit rate link to increase bandwidth efficiency, without compromising the underlying channelized, guaranteed-bandwidth nature of the individual communication channels.

Abstract: A module that includes both an “add-in”/“drop-out” pair of ports and a “drop-in”/“add-out” pair of ports comprises an arrangement of elements that combines an optical signal having a chosen wavelength with an optical signal applied at the “add-in” port, and outputs the combined signal at the “add-out port.” Concurrently, the module extracts an optical signal with the same wavelength from an optical signal applied at the “drop-in” port signal, yielding an optical signal at the “drop-out” port that is missing that same wavelength. When the amount of information that needs to be sent from a first network node to a second, remote, node, is greater than that which a single wavelength can handle, a plurality of the above-described modules are interconnected within the first node by optically coupling the “add” ports in a “daisy chain” fashion and the “drop” ports in a “daisy chain” fashion, with each module operating at a different wavelength.

Abstract: A data packet transport arrangement includes a tag-based packet multiplexer and a tag-based packet demultiplexer, that utilizes an identification tag to identify packets to each of the N input channels so as to provide a logical transport channel for each of the N channels through the packet transport arrangement. The data transport arrangement thereby allows aggregating multiple communications channels into a higher bit rate link to increase bandwidth efficiency, without compromising the underlying channelized, guaranteed-bandwidth nature of the individual communication channels.

Abstract: A system for data transmission and communication receives a plurality of Gigabit Ethernet data packets from multiple Gigabit Ethernet links. The system bit multiplexes the data packets, on a bit by bit basis, together onto a fiber optic link. At the output of the fiber optic link, the bits are demultiplexed into data packets and transmitted onto multiple Gigabit Ethernet links. The high speed fiber optic link transmits the data at higher speed than is possible over each individual Gigabit Ethernet link.

Abstract: A high-speed access data network in which upstream and downstream traffic is logically or physically separated. The network can use the Ethernet media access control (MAC) layer protocol over distances that are much larger than conventionally possible with the Ethernet MAC layer protocol. In a configuration including a central office and multiple subscribers, the central office is removed from the collision domain, which can be made relatively small, without limiting the distance between the central office and the subscribers. The downstream data rate is not limited by the size of the collision domain and can thus be made almost arbitrarily large. Furthermore, by allowing a smaller collision domain, greater upstream data rates can be used. It is thus possible to use ubiquitous and inexpensive Ethernet LAN technology in highly cost-sensitive applications such as residential broadband access.

Abstract: An optical local area network uses modified remote network interface cards (NICs) to provide an optical carrier signal for signaling use by a centralized optoelectronic switch unit. The NIC optical transceiver is modified so that instead of being normally “off” during the standby mode, the data signal is logically inverted to be “on.” Light from each NIC is used to provide optical power for a corresponding optical modulator on the switch unit.

Abstract: A method and apparatus for overcoming modal noise penalties associated with multi-mode fiber optic links operating at high data rates on the order of 10 Gb/s. The method involves restricting the center launch condition of optical signals into the multi-mode fiber while permitting loose tolerances between source and fiber.

Abstract: A statistically-multiplexed link for transporting aggregated data from multiple clients to a central server. A concentrator is used to separate packets containing valid data (live packets) from invalid (dead) packets. When combined with a conventional multiplexer, the concentrator circuit provides arbitration on a first-come first-served basis and allows a smaller multiplexer to service a larger number of inputs thereby enabling a more statistically efficient multiplexed link.

Abstract: A method of fabricating oxide-apertured vertical cavity surface emitting lasers involving the steps of: i) defining, during the fabrication of one or more VCSELs on an electronic chip, a number of mesa structures of different sizes; ii) selectively oxidizing the chip and mesa structures to produce an oxide-aperture for each structure; iii) inspecting the chip to determine which one of the mesas is desired or optimal; iv) choosing an appropriate metalization mask that serves to metalize and electrically connect only that desired mesa structure; and v) depositing, a dielectric top mirror on that electrically connected mesa. Advantageously, the method may be practiced using a variety of fabrication techniques and apparatus that are compatible with conventional devices. A distinguishing characteristic of our inventive method, is that only a desired or optimal mesa is completed while the remaining mesas on a particular chip remain unprocessed.

Abstract: A high-capacity, chirped-pulse wavelength-division multiplexed communications apparatus and method in which a chirped-pulse, wavelength-division multiplexed signal is further optically multiplexed thereby enhancing bit rates per channel. A multifrequency optical source for supplying an optical signal having a number of wavelength division multiplexed (WDM) channels; a power splitter for splitting the optical signal from the multifrequency source into a number of signals; a number of time delay lines, for delaying each one of the signals independently; a number of data encoding modulators for modulating each one of the delayed signals; and a power combiner for combining the number of delayed, modulated signals into a single signal such that the multifrequency optical source signal is multiplexed by a desired amount.

Abstract: Low-noise, bidirectional communications in a fiber optic cable is achieved by coupling a first end of the cable to an optical power source having an inherently broad spectral width. A second end of the cable is coupled to an optical detector having a detector bandwidth, such that the bandwidth of the optical power source is greater than the detector bandwidth. When the bandwidth of the optical power source is large compared to the bandwidth of the detector, the beat frequencies resulting from coherent Rayleigh noise fall outside the bandwidth of the detector and are not detected.

Abstract: A network for multi-bit word parallel communication between optoelectronic chips on a two dimensional array of optical input and output channels carried on a single dimension of optical fibers. Each bit of a word is carried on a different wavelength and the multiple wavelengths carrying a word are wavelength multiplexed onto a single optical fiber. Multiple fibers can be joined into a one dimensional array of fibers. A transceiver for transmitting and receiving along the optical data channels comprises an array of modulators powered by individual wavelength light beams, either from individual monochromatic light sources and a light beam from a single broadband light source made to pass through a diffraction grating. The modulators are positioned so that each modulator reflects a different wavelength light beam, thereby providing multiple optical channels. Alternatively, multiple wavelengths are generated from CMOS integrated light sources.

Abstract: Providing a compositional image of an object in real time is accomplished by illuminating the object with a waveform comprising pulses of electromagnetic radiation in the terahertz frequency range and measuring the relative time delays of pulses reflected by the object to determine the positions of dielectric interfaces in the object. According to a further embodiment, the waveform includes one or more pulses of terahertz radiation, each pulse having a duration in the range of approximately 10 to 10,000 femtoseconds.

Abstract: A network for multi-bit word parallel communication between optoelectronic chips on a two dimensional array of optical input and output channels carried on a single dimension of optical fibers. Each bit of a word is carried on a different wavelength and the multiple wavelengths carrying a word are wavelength multiplexed onto a single optical fiber. Multiple fibers can be joined into a one dimensional array of fibers. A transceiver for transmitting and receiving along the optical data channels comprises an array of modulators powered by individual wavelength light beams, either from individual monochromatic light sources and a light beam from a single broadband light source made to pass through a diffraction grating. The modulators are positioned so that each modulator reflects a different wavelength light beam, thereby providing multiple optical channels. Alternatively, multiple wavelengths are generated from CMOS integrated light sources.

Abstract: A time-domain signal processing system for displaying, classifying, and recognizing temporal and spectral features in terahertz waveforms returned form materials. Specifically, novel techniques are described for classifying and analyzing the free induction decay exhibited by gases excited by far-infrared (terahertz) pulses. Illustratively, a simple geometric picture may be used for the classification of the waveforms measured for unknown gas species and gas mixtures.

Abstract: A unique time slot is assigned to each of a plurality of wavelengths emitted by a single, centralized wavelength division multiplexed optical source to provide a "bit interleaved" WDM signal. In accordance with an illustrative embodiment of the present invention, the thus-developed bit-interleaved WDM signal is replicated in cascaded stages of amplification and power splitting before data is encoded for respective frequency dependent receivers as, for example, a plurality of passive optical networks. Because the output of the optical source need not be encoded with data for the respective receivers until after many stages of splitting and amplification, a small number of time division multiplexing (TDM) modulators synchronized to the source may be used to deliver data to potentially tens of thousands of subscribers.

Abstract: A network for multi-bit word parallel communication between optoelectronic chips on a two dimensional array of optical input and output channels carried on a single dimension of optical fibers. Each bit of a word is carried on a different wavelength and the multiple wavelengths carrying a word are wavelength multiplexed onto a single optical fiber. Multiple fibers can be joined into a one dimensional array of fibers. A transceiver for transmitting and receiving along the optical data channels comprises an array of modulators powered by individual wavelength light beams, either from individual monochromatic light sources and a light beam from a single broadband light source made to pass through a diffraction grating. The modulators are positioned so that each modulator reflects a different wavelength light beam, thereby providing multiple optical channels. Alternatively, multiple wavelengths are generated from CMOS integrated light sources.

Abstract: A THz imaging system with the emitter region of the THz generator designed so that the sample to be analyzed is placed in the near field of the generator allows radiation to impact the sample without intervening optics.

Abstract: Optical system architectures with improved spatial resolution are provided in which the radiation useful for THz spectroscopy and other investigative procedures can be directionally coupled, in a highly efficient manner, into and out of photoconductive structures such, for example, as dipole antennas. An optical system constructed in accordance with an illustrative embodiment of the present invention comprises a source for emitting radiation in a range of frequencies within from 100 GHz to 20 THz, a coupling lens structure for coupling radiation emitted by said source into free space, at least one collimating optical element for collimating received coupled radiation into a beam having a substantially frequency independent diameter and substantially no wavefront curvature, and a detector for detecting the beam collimated by the at least one collimating optical element.

Abstract: An optical signal attenuation device and associated method for selectively attenuating the signal strengths of different wavelength signals contained within a multiplexed optical transmission. The attenuation device includes a diffracting element that diffracts the multiplexed optical system and directs the different wavelength signals onto separate optical paths. A modulator array is provided that contains a plurality of optical modulators spaced at a pitch so that each modulator receives one of the different wavelength signals. Each optical modulator causes a signal to be produced that correspond to the signal it receives, except that the signal strength of the emitted signal is altered to fall within a desired range. Each signal emitted by the optical modulators is again directed toward a diffraction element. The diffraction element combines the separate wavelength signals, thereby producing a multiplexed signal where each wavelength has a signal strength that falls within a common range.