Abstract: In an optical transmission system, a first modulated signal is generated at the transmitting end by modulating a first carrier signal with a first data signal and a second modulated signal is generated by modulating a second carrier signal, which differs from the first carrier signal by a differential frequency, with a second data signal. The first and second modulated signals are polarized orthogonally with respect to one another and combined to form an optical multiplex signal and are transmitted. At the receiving end, the optical multiplex signal is conducted via a polarization control element to a polarization splitter which splits the optical multiplex signal into the first and second modulated signals.

Abstract: A communications network has a plurality of nodes interconnected by an optical transmission medium. The transmission medium is capable of a carrying a plurality of wavelengths organized into bands. A filter at each node for drops a band associated therewith and passively forwards other bands through the transmission medium. A device is provided at each node for adding a band to the transmission medium. Communication can be established directly between a pair of nodes in the network sharing a common band without the active intervention of any intervening node. This allows the network to be protocol independent. Also, the low losses incurred by the passive filters permit relatively long path lengths without optical amplification.

Abstract: An optical communication system which uses optical phase conjugation to compensate for chromatic dispersion and optical Kerr effect. The optical communication system includes a first fiber, a phase conjugator, and a second fiber. The first fiber transmits a light signal therethrough, and is a polarization maintaining fiber. The light signal is a linear polarized wave. The phase conjugator receives the light signal from the first fiber and produces a corresponding phase conjugate light signal. The second fiber receives the phase conjugate light signal from the phase conjugator and transmits the phase conjugate light signal therethrough. A wavelength division multiplexing optical communication system is also provided which uses optical phase conjugation to compensate for dispersion and optical Kerr effect.

Abstract: In a communication network, a logical connections is realized by defined connection paths, with each connection containing at least one connection segment path, whereby a working connection path routed by a “star point” network node and a geographically different substitute connection path routed by another “star point” network node are provided for each connection. In addition, through-switching means are provided in the “star point” network nodes for the switching through of the connections, respectively, by the working connection path and the substitute connection path.

Abstract: An optical packet is provided with an amplitude modulated (ASK) payload and a differential phase shift keyed (DPSK) header so that a routing address in the header can be read and modified at a network node without having to inject light at this node to do this modification. With ASK, though it is easy to convert a high-level bit to a low-level bit by simple attenuation, the conversion of low-level bit to high-level bit requires light injection. With DPSK, bit conversion can be effected without light injection, merely requiring passage through a phase modulator.

Abstract: An optical transmission apparatus capable of suppressing SBS by multiplexing an input signal with a pilot signal, and further capable of eliminating an adverse effect of intermodulation distortion between the input signal and the pilot signal is provided. When the input signal is a frequency-multiplexed signal obtained by multiplexing a plurality of signals aligned on a frequency axis at regular intervals &Dgr;f (&Dgr;f>0), a pilot signal generation part generates the pilot signal having a frequency {m−(1/2)}×&Dgr;f (m is an arbitrary natural number). A multiplex part multiplexes the input signal (electrical signal to be transmitted) with the pilot signal generated by the pilot signal generation part. An electrical-optical conversion part converts an electric signal outputted from the multiplex part into an optical signal through direct intensity modulation.

Abstract: An optical switch comprising switching means arranged to switch an optical signal by redirection of the optical beam path of said signal, wherein said optical switch is arranged to misalign the optical beam path so as to provide a predetermined optical output power. Thus a switch can be directly used to attenuate a signal, instead of utilising separate attenuators.

Abstract: An optical interconnection system for the realization of network elements in optical networks comprises a set of functional optical circuit modules (15) and an interconnection panel (10). The panel is provided with a row of module positions (13.1, 13.2, 14.1, . . . , 14.N) suitable for plugging in circuit modules (15), and with a pair of optical (1:N) splitters (16,17), each pair of corresponding ports of which (16A/17A, 16.1/17.1, . . . , 16.N/17.N) are interconnectable to a pair of a number of pairs of connection ports (11, 12.1, . . . , 12.N) through a module position and a circuit module plugged into that position. The set of circuit modules comprises circuit modules with functions for signal interconnection, for signal transport direction reversal, and for signal manipulation. A number of panels can be coupled together for purposes of, inter alia, expansion and/or protection.

Abstract: An external modulation optical communication system suppressing the intensity noise of a semiconductor laser source by making substantially different optical path lengths for the optical paths in the interferometric modulator. Noise reduction is dependent on the correlation between intensity noise and frequency noise of the semiconductor laser. The interferometer path delay difference forms an optical filter that transforms frequency fluctuations into intensity fluctuations that are out of phase with the laser intensity fluctuations. The intensity modulation induced by frequency noise can be out of phase with the optical source intensity fluctuations, leading to total intensity noise at the output of the optical link which is lower than the laser intensity noise. Because the optical interferometer is already present for optical modulation, the optical filter realized by the unequal path delays of the interferometer does not add optical loss.

Abstract: The present invention provides a remodulating channel selector for a wavelength division multiplexed optical communication system. The remodulating selector receives a WDM input signal, selects a particular optical channel from the WDM signal and places the information from the selected signal onto a newly-generated optical output signal. The wavelength of the output optical signal can be the same as or different from one of the optical channels which comprises the WDM input signal. When used in a WDM optical communication system with remodulators at the transmission input, the remodulating selectors provide complete control over the interfaces with optical transmitters and receivers, permitting use with a broad range of optical equipment.

Abstract: An optical translator that includes an interferometer and a plurality of semiconductor optical amplifiers (SOAs) coupled to the interferometer. The at least two of the SOAs receives data and a clock signal. The data is received by the at least two SOAs at different times. A coupler combines each of a respective output of the at least two SOAs to provide output data. The output data is a retimed and a reshaped signal of the data provided to at least one of the plurality of SOAs.

Abstract: A method and apparatus is provided for connecting an optical source to a multimode optical fibre in a multimode optical fibre communications system. A single mode fibre length is provided such that optical radiation admitted from an optical source at one end of the single mode fibre length is provided to a multimode optical fibre at the other end of the single mode fibre length. This method and apparatus is used in a duplex patchcord for connecting an optical transceiver to a pair of installed multimode fibres. The second fibre in the patchcord is a multimode fibre for passing optical signals to the optical receiver of the transceiver.

Abstract: A transmission of optical signals generated by multi-line optical sources is provided via multichannel WDM optical network. Each multi-line optical source generates optical spectral lines within designated spectral range associated with the spectral window allocated for corresponding WDM channel, and comprises a plurality of spectral lines. Spectral lines are substantially narrower than the spectral separation between the lines.

Abstract: A technique in accordance with the present invention provides a systematic approach to find a sub-optimum channel plan with reasonable computational time. In each step, this technique allocates channels to minimize the FWM crosstalk in terms of fiber characteristics, while selecting as many channels as possible to increase the bandwidth efficiency.

Abstract: An Improved Infrared Signal Communication System and Method Including Transmission Means Having Automatic Gain Control is disclosed. Also disclosed is system and method that adjusts signal transmission power in response to incident signal power amplitude. The preferred system includes a control signal loop within the signal receiving system, and the system further includes a signal transmitting system that is responsive to the control signal loop. The preferred system includes manual, semi-automatic and automatic modes of operation. Still further, the preferred method includes at least two Ir-enabled appliances “stepping” each other “down” in transmit power in response to directives issued by the other Ir-enabled appliance.

Abstract: An errorless switching system is disclosed that is comprised of a fault detector, a synchronization system, and a switching system. The synchronization system aligns a first data signal and a second data signal. The fault detector detects errors in the data signals and instructs the switching system to transfer the first data signal or the second data signal to avoid transferring the erroneous data. No data is lost or duplicated because the data signals are aligned at the switching system.

Abstract: A Metropolitan Area Network (MAN) is disclosed that is comprised of a central node, an optical fiber, a first low insertion loss Optical Add-Drop Multiplexer (O-ADM), a second low insertion loss O-ADM, and a third low insertion loss O-ADM. The first, second, and third O-ADMs are coupled to the optical fiber and configured to drop wavelengths from an optical signal. The first, second, and third O-ADMs each have an insertion loss of less than approximately 1.00 dB. The low insertion loss O-ADMs create an efficient MAN that can grow much larger than current MANs in the absence of optical line amplifiers.

Abstract: An optical signal transmitter is disclosed that transmits an optical signal with corresponding Wavelength Division Multiplexing (WDM) channels and Time Division Multiplexing (TDM) channels. The transmitter is comprised of a laser, a dispersion system, and a modulator. The laser generates and transmits a narrow laser pulse comprised of a plurality of wavelength channels. The dispersion system broadens the narrow laser pulse into a wide laser pulse. The modulator modulates the wide laser pulse based oh an electric modulation signal comprised of a plurality of time slot channels wherein the time slot channels in the electric modulation signal correspond to the wavelength channels in the wide laser pulse respectively. The modulator transfers a modulated wide laser pulse. Channels of the modulated wide laser pulse are hybrid wavelength and time slot channels. The transmitter singularly transmits a WDM optical signal comprised of multiple wavelength channels.

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 header routing information has sufficiently different characteristics from the data payload so that the signaling header can be detected without being affected by the data payload, and that the signaling header can also be removed without affecting the data payload. The signal routing technique can overlaid onto the conventional network elements in a modular manner using two types of applique modules. The first type effects header encoding and decoding at the entry and exit points of the data payload into and out of the network; the second type effects header detection at each of the network elements.

Abstract: Two optical signals of the same wavelength are polarization filtered at a sending end into orthogonal polarization orientations, and then added into a single optical transmission signal having various polarization components. The optical transmission signal is transmitted via an optical data link to a receiving end having a splitter. Portions of the optical transmission signal are inputted to different polarization filters logically corresponding to those at the sending end, to recover the two optical signals originally sent.