Abstract: A distributed optical amplifier for use with soliton transmission, which reduces the effects of soliton—soliton interaction by introducing an optimum excursion in the soliton intensity. A optimum operating regime is found wherein both the pulse intensity oscillations and the soliton—soliton interactions are taken into account.

Abstract: A cross-connect for a multi-ring, multi-channel telecommunications network, especially for a wavelength-division multiplexed (WDM) optical network. Each of the interconnected rings is self-healing by provision of a redundant counter-rotating ring or excess capacity on pairs of counter-rotating rings. Because an interconnect between self-healing rings does not need to connect working to protection fibers, or similarly redundant fibers, the complexity of the interconnect can be substantially reduced. For several important architectures, the interconnect can be decomposed into one or two 3x3 interconnects. Further, a wide-sense non-blocking 3x3 interconnect can be advantageously implemented as four 2x2 switches, which may be a basic building block of optical switches. A novel algorithm is available to add new paths through such a 3x3 interconnect. The interconnect can be decomposed into one or two 4x4 interconnects when another pair of add/drop lines are added.

Abstract: A device comprises a plurality of nodes and four optical transmission lines of clockwise and counter-clockwise working operation lines and clockwise and counter-clockwise stand-by lines which connect the nodes in form of a ring. Each node is provided with first and second terminal sections including a receiver and transmitter, with a first optical path switch for switching the optical path between four output terminals of the counter-clockwise working operation and stand-by optical transmission lines, the second terminal section, and output terminal of a first stand-by line, and four input terminals of the clockwise operation and stand-by optical transmission lines, first terminal sections, and a second stand-by line.

Abstract: A method and apparatus for a free space optical non-processing satellite transponder includes the step of receiving a phase modulated optical communication signal in a satellite. This phase modulated optical communication signal has been formed by phase modulating an optical carrier signal with a broad band frequency division multiplexed communication signal. The signal is passed through an optical heterodyne receiver to produce a broad band frequency division multiplexed communication signal. Part of the signal is split off for on-board satellite processing. The balance of the signal is combined within a power combiner with a radio frequency signal from an on-board source of the satellite to form a combined broad band frequency division multiplexed communication signal.

Abstract: A device (1) and process providing an interface between a user (2) and an apparatus (3) which can be remotely controlled by infrared radiation (4). The device includes an infrared signal reception device (16) and at least one series connection (18) as well as a device which process infrared signals corresponding to the programmable apparatus, can code in ASCII and then store the infrared signals in a read-write memory (20) and process the signals coded in this way and/or stored data in order to carry out a specification application. The device also includes at least one individual sensitive sensor which can be actuated by the user and can trigger the emission of the infrared signals for the remote control of the apparatus from the processing device such that the specific application is carried out at least in part.

Abstract: An optical signaling header technique applicable to optical networks wherein packet routing information is embedded in the same channel or wavelength as the data payload so that both the header and data payload propagate through network elements with the same path and the associated delays. The technique effects survivability and security of the optical networks by encompassing conventional electronic security with an optical security layer by generating replicated versions of the input data payload at the input node, and the transmission of each of the replicated versions over a corresponding one of the plurality of links. Moreover, each of the links is composed of multiple wavelengths to propagate optical signals or optical packets, and each of the replicated versions of the data payload may be propagated over a selected one of the wavelengths in each corresponding one of the plurality of links.

Abstract: A clipping distortion controlling circuit for stabilizing an amount of generation of the clipping distortion. A level of the clipping distortion generated by a light-emitting semiconductor laser element is monitored through a light-receiving element and a band-pass filter. A limiter-level of a pre-clipping circuit is changed to be controlled in accordance with the level of the clipping distortion. For this reason, it is capable of coping with the level-fluctuation of the clipping distortion caused by gain-change of an amplifier or by characteristic degradation of the light-emitting element, so that clipping distortion generation has a stabilized characteristic.

Abstract: In a multichannel wave division multiplexer system the simultaneous bidirectional transmission through a single optical fiber of at least first and second optical signals each having a first wavelength is provided by electrically isolating each respective optical transmitter from the optical signal of the other optical transmitter.

Abstract: An optical device has an optical switching unit and a variable filter. the optical switching unit connects a pair of single direction optical transmission lines to a bi-directional optical transmission line carrying optical signals of different wavelengths in different directions relative to the optical switching unit. The single direction optical transmission lines carry optical signals in single different directions relative to the optical switching unit. The variable filter has first and second opposing terminal pairs such that optical signals of different wavelengths input to one terminal of one terminal pair are filtered with a portion of the different wavelengths being output to one terminal of the opposing terminal pair and the remainder of the different wavelengths being output to the other terminal of the opposing terminal pair. The bi-directional optical transmission line is coupled to one terminal of the variable filter. The optical switching unit may include an optical circulator.

Abstract: In an optical signal receiving apparatus, an electrical switch is turned on to put a semiconductor laser into an oscillating state to invert an input optical signal. Mutual gain modulation is carried out in a semiconductor optical amplifier due to the input optical signal. A transmission wavelength of a variable wavelength optical filter is matched with an oscillation wavelength of the semiconductor laser and then an inverted optical signal is supplied to an optical receiving unit. If the input optical signal is not be inverted, the electrical switch is turned off to put the semiconductor laser into an unoscillating state. The semiconductor optical amplifier only carries out optical amplification without the mutual gain modulation. The transmission wavelength of the variable wavelength optical filter is matched with an input wavelength of the input optical signal and a noninverted optical signal is supplied to the optical receiving unit.

Abstract: A wavelength converter incorporating an on-chip integrated laser for use in an optical system. The converter includes a first port for receiving an optical input signal such as a WDM signal and providing it to an interferometer, and an output port for outputting a signal which is a wavelength-converted version of the input signal. An optical source or laser is fabricated on the chip substrate on which the interferometer is formed for providing operating power to the interferometer. Power levels of the input signal are maintained by adjusting an on-chip semiconductor optical amplifier that receives the optical input signal and provides the amplified signal to the interferometer. In an alternative embodiment, the on-chip optical source is replaced by an on-chip pre-amplifier for an external laser source.

Abstract: An optical-wavelength division multiplexing system, method and branching unit. The arrangement drops one, or more than one, predetermined wavelength signal(&lgr;2) from a trunk(18) onto a branch and adds signals(&lgr;2′) at the predetermined wavelength, or at a predetermined different wavelength from the branch out of the trunk. A sensor(34) senses the level of the signal(s) dropped and a controller(36), which responds to the control signal, adjusts the level of the add signal(s)(&lgr;2′) to an optimum level for adding to the trunk(18).

Abstract: A WDM add/drop device for use in an optic communications system for adding and dropping optical wavelengths from a multiple-wavelength optical system. The device includes a set of lenses, a planar grating wavelength multiplexer and a micromirror array switchable for individual wavelengths of the multiple-wavelength signal between a transmit mode and a reflect mode. The grating angularly demultiplexes a multiple-wavelength optical signal in a first direction and the individual wavelengths are processed by the micromirror array and directed to the grating in a second direction. The micromirror array will either reflect select wavelengths to a first port or transmit select wavelengths to a second port. In a preferred embodiment, ports on a first multiport circulator input the multiple-wavelength optical signal to the WDM add/drop device and output the multiple-wavelength optical signal from the WDM add/drop device.

Abstract: An array antenna is steered by moving two sets of optical fibers of different optical lengths between a number of light signal sources and an array antenna. By changing the lengths of the optical paths of the different light signal sources, the wave front can be steered. The light signal traverses five sections of optical delay lines with at least two selectable optical lengths. One set of selectable optical lengths provides coarse adjustment of steering, and a second set of selectable optical lengths provides fine adjustment of steering. The coarse adjustment is implemented by using a larger increment of selectable optical lengths between adjacent optical lengths than the increment for the fine adjustment. The antenna can serve both for a transmitter or a receiver.

Abstract: A method for extracting a timing signal produces a data signal from a first portion of an optical signal, extracts a timing signal from a second portion of the optical signal and adds dispersion compensation to at least one of the first and second portions of the optical signal to thereby control the amount of total dispersion in the second portion of the optical signal to be substantially different from the amount of total dispersion in the first portion of the optical signal. The timing signal extracting device uses a signal reproduction circuit to produce the data signal, a signal extraction circuit to extract the timing signal and a chromatic dispersion control apparatus to add dispersion compensation. The optical signal may be modulated by a data signal having a bit rate of X bits/second and the extracted timing signal may have a frequency of X hertz. The signal extraction circuit may be used with a phase locked loop.

Abstract: An improved access system for use in a Fiber-In-The-Loop (FITL) communications network is disclosed. The access system comprises a host digital terminal (HDT) and a plurality of subtending optical network units (ONUs). The digital signal processing (DSP) functions traditionally executed by line interface units (LIUs) within the ONUs are migrated to the HDT, rendering the individual ONUs simpler, cheaper and more reliable. This is made possible by the provision in each ONU of an oversampling codec for sampling (and conversion) of upstream and downstream data at a very high bit rate. The large bandwidths of the data communicated between the ONUs and the HDT are easily handled by the fiber optic medium therebetween. In the HDT, DSP functions are executed by a common pool, or bank, of DSP ASICs. Decimators are provided in the HDT in order to properly format the data for processing by the DSPs.

Abstract: An optical wavelength conversion apparatus includes a polarization switchable semiconductor laser whose oscillation polarization mode is switchable between two independent polarization modes (typically, TE and TM modes) of different wavelengths, depending on its stimulated condition, a first unit for selecting a polarization mode for light input to the semiconductor laser from among the two independent polarization modes, and a second unit for selecting a polarization mode for light emitted from the semiconductor laser from among the two independent polarization modes. As a result, a wavelength of the light of the polarization mode selected by the first unit is converted into another wavelength of the light of the polarization mode selected by the second unit.

Abstract: An optical receiver having a photodiode and a preamplifier includes a charge controller which charges a capacitor depending on an received voltage signal at each burst timing of the burst-mode signal and then discharges the capacitor with a predetermined time constant to produce an amplitude-varying offset component. The current signal of the photodiode is controlled so that the amplitude-varying offset component is canceled out.

Abstract: Apparatus for implementing the application of duo-binary signal encoding in high-power, high-speed transmission systems which may be employed to mitigate the problem of stimulated Brillouin scattering. A dual-drive Mach-Zehnder interferometer modulator is used, with data being applied to both modulation inputs. The voltage difference between the two modulation inputs is between −V&pgr; and +V&pgr;. In one embodiment, the data signal is applied to one input, and the same signal, delayed by one bit, is applied to the second input, and the modulator is biased so as to have minimum throughput when both inputs are identical. In the second embodiment, the data signal is applied to one input and the complementary data-bar signal, delayed one bit, is applied to the second input, with the modulator biased to minimum throughput when both inputs are identical. This novel implementation has been verified experimentally showing a power penalty of less than 1 dB relative to a conventional binary signal.

Abstract: A universal demarcation point for managing the delivery of communications services to a subscriber that provides an interface between a utility distribution network and subscriber owned equipment. The universal demarcation point includes a utility accessible portion and a subscriber accessible portion. The utility accessible portion has an input port, an output port, a plurality of modular connectors, a power supply, and a plurality of service modules. The input port provides access to the universal demarcation point for delivery of communications service from the utility distribution network. The communications services are delivered through a hybrid cable. The hybrid cable has a plurality of fiber optic cables and a plurality of copper cables. The fiber optic cables are capable of transmitting light signals and the copper cables are capable of transmitting electric power.