Abstract: A technique is proposed for performing add/drop operations in an OADM assembly serving an optical network and comprising an add unit and a drop unit. With respect to at least one optical channel assigned to an optical wavelength ?, the OADM assembly is capable of dropping the channel from the network via the drop unit as a first signal, and adding the channel to the network via the add unit as a second signal. According to the technique, the OADM assembly additionally comprises an authentication and control unit ACU for authenticating the at least one optical channel and controlling the OADM assembly. The ACU is authenticates the optical channel by comparing one or more components of the first signal with one or more components of the second signal serving as a reference, and based on the authentication result, makes decisions whether to allow or block the dropping and/or adding of the optical channel.

Abstract: A network with nodes interconnected by optical fiber links carrying an optical communication channel having a single optical wavelength. In the network, at least two network nodes operate as transmitting nodes generating a first short pulse optical signal at different bit rates; at least one of the other network nodes operates as a receiving node and is designated to receive transmissions from at least one of the transmitting nodes via the optical channel in a form of a second short pulse optical signal. The receiving node is provided with a dispersion compensation module adapted to compensate dispersion created in the optical fiber along the optical channel between a specific transmitting node and the receiving node, thereby ensuring receipt, in a restored form, of data transmitted using the second optical signal and directed to the receiving node.

Abstract: Technology is proposed for estimating one or more characteristics of a main signal transmitted via a communication link, wherein the main signal is composed from a number of component signals possibly comprising respective data signals and transmitted via a number of respective communication channels. The technology comprises providing an analyzing circuit independent from the communication link, transmitting a probe data signal in the analyzing circuit, monitoring a bit error rate (BER) parameter associated with the probe data signal and introducing into the analyzing circuit at least a portion of energy of the main signal as an interference signal. The technology allows judging about characteristics of the main signal based on changes in the monitored BER parameter of the probe data signal.

Abstract: A technique for determining averaged Q-factor, Qavg, for an optical binary signal transmitted at a bit rate X, based on amplitude histogram evaluation and on asynchronous sampling. The technique is inexpensive since it uses sampling pulses, which have bit rate Y lower than X and are not synchronized with the optical signal. The technique proposes conducting N sampling sessions and constructing N respective amplitude histograms for the sessions, wherein an initial session is conducted at a randomly selected initial phase of the sampling pulses, and N?1 sessions are held at different phases shifted in respect of the initial phase. The technique then compares the obtained N amplitude histograms to select there-from the amplitude histogram having the minimal cumulative value of cross-point data. The averaged Q-factor is determined from the selected histogram, with accuracy comparable with that of synchronous methods.

Abstract: A technique is described for controlling and optical network composed of network elements (NEs), with the aid of a network controller (NC) being in communication with the network elements. The technique includes collecting, by the network controller NC, information on the NEs therefrom, and, whenever a change in the network is requested, simulating within the NC operation of the network with the requested change and based on the collected information. The NC makes a decision on acceptability of the requested change, and may then cause implementation of the requested change in the network.

Abstract: A technique for carrying out protection of data traffic in a multi-channel multi-section optical communications network by simultaneously using Optical Multiplexed Section (OMS) protection and Optical Channel (OCH) protection; the technique comprises selection of a working optical signal in an OCH protected optical channel, in case of a fault in a section of the network, by relying on an indication associated with OMS switching functionality that is required to overcome the mentioned fault.

Abstract: A method and a system for performing pre-emphasis of one or more optical channels respectively carrying one or more optical signals, by effecting bit rate of the one or more of the signals, thereby adjusting BER value thereof.

Abstract: A method, a system and a module are proposed for detecting and locating faults in an optical multi channel network composed of network nodes. The method includes assigning different sub-carrier pilot tones to a number of the nodes comprising Network Elements (NE), applying the different sub-carrier pilot tones to any signal added to the network via the respective nodes, checking presence of one or more of the sub-carrier pilot tones at one or more points of the network, and, based on results of the checking, locating a faulty section of the network in case a fault occurred.

Abstract: A method, a system and a device for encrypting an optical signal to be transmitted via an optical fiber communication link by causing controlled chromatic dispersion of said signal. The controllable decryption device, as well as the controllable decryption device, can be implemented in the form of a variable dispersion compensation module controlled by a decryption key. In the system, the encryption device and the decryption device are controlled in synchronism by an encryption key and a decryption key respectively, the keys preferably being functions of time symmetric with respect to the time axis.

Abstract: An optical switching apparatus in an optical communication network selectively combines and separates, using OTDM and/or WDM, optical signal samples that are obtained by a spread spectrum technique or a combination of optical signal samples that are obtained by a spread spectrum technique and optical signal samples that are carried over discrete channel wavelengths. In upstream communication, when optical signal samples that are received at the optical switching apparatus include upstream optical signal samples that are obtained by a spread spectrum technique, the optical switching apparatus optically converts the optical signal samples provided thereto into a broadband combined series of upstream optical signal samples and routes the broadband combined series of upstream optical signal samples to a destination route.

Abstract: An optical extending device for use in transmission of optical signals which comprise at least one sequence of periodic optical signals, said optical device comprising: a first fiber optic having a characteristic dimensional propagation coefficient equal to ?1 and adapted to be connected to a single mode second fiber optic having a length equal to L0 and a characteristic dimensional propagation coefficient equal to ?0, wherein Lp, the length of said first fiber optic is substantially equal to {[T2/??L0*?0]/?1}*{1?MOD(L0/{T2/??L0*?0]/g(b)}} and wherein: n is an integer 1, 2, 3 . . . and is selected in accordance L0, the length of the single mode second fiber optic; T is a time period of the periodic optical signals; and MOD is the remainder obtained from dividing 10 by {[T2/??L0*?0]/?1}.

Abstract: A communication apparatus for use with a light source providing a light beam having a wavelength ?. The apparatus comprises at least one optical modulator adapted to modulate the light beam to a modulated light signal which comprises at least two additional spectral components, one of which at a wavelength of ?+?? and the other at a wavelength of ????. The apparatus further comprises an optical splitting device adapted for coupling to the at least one optical modulator, for splitting the modulated light signal into at least two similar modulated light signals and at least two optical filters, each adapted to receive one of said at least two similar modulated light signals and to allow one of said at least two additional spectral components to egress therefrom.

Abstract: The invention proposes a technique for measuring chromatic dispersion in an optical communication line transmitting an optical signal at a predetermined optical wavelength. The technique comprises determining the sign of chromatic dispersion and includes introducing controlled changes of wavelength around the predetermined wavelength, monitoring the optical signal that has passed said line, and obtaining a first and a second signals, wherein the first signal reflects changes of the carrier wavelength, and the second signal reflects changes of delay of the optical signal transmitted via the line. The two signals are compared and the chromatic dispersion sign is determined based on the phase difference there-between.

Abstract: The invention proposes a technique for measuring chromatic dispersion in an optical communication line transmitting an optical signal at a predetermined optical wavelength. The technique comprises determining the sign of chromatic dispersion and includes introducing controlled changes of wavelength around the predetermined wavelength, monitoring the optical signal that has passed said line, and obtaining a first and a second signals, wherein the first signal reflects changes of the carrier wavelength, and the second signal reflects changes of delay of the optical signal transmitted via the line. The two signals are compared and the chromatic dispersion sign is determined based on the phase difference there-between.

Abstract: Technology is proposed for estimating one or more characteristics of a main signal transmitted via a communication link, wherein the main signal is composed from a number of component signals possibly comprising respective data signals and transmitted via a number of respective communication channels. The technology comprises providing an analyzing circuit independent from the communication link, transmitting a probe data signal in the analyzing circuit, monitoring a bit error rate (BER) parameter associated with the probe data signal and introducing into the analyzing circuit at least a portion of energy of the main signal as an interference signal. The technology allows judging about characteristics of the main signal based on changes in the monitored BER parameter of the probe data signal.

Abstract: A technique for handling an optical pulse signal, wherein the handling includes one or more operations out of: pulse shaping, treatment of nonlinearity and monitoring; the technique uses a device capable of performing a cascaded second harmonic generation (SHG) with respect to a particular fundamental harmonic (FH), and comprises: selecting in the device a particular optical path length suitable for performing at least one of the above operations with respect to an incoming optical pulse signal carried by a wavelength defined by the particular fundamental harmonic (FH), conveying the incoming optical pulse signal carried by the defined wavelength along the selected optical path in the device, obtaining from the device an output optical pulse signal at the fundamental harmonic (FH), wherein the treatment of nonlinearity and/or the pulse shaping are performed, and/or obtaining an output optical pulse signal at the second harmonic (SH) for further monitoring it and judging about the input optical pulse signal

Abstract: A method and a system for traffic management in an optical network, based on measuring chirp of optical signals transmitted along an optical path extending in the network.

Abstract: A method and a system for performing pre-emphasis of one or more optical channels respectively carrying one or more optical signals, by effecting bit rate of the one or more of the signals, thereby adjusting BER value thereof.

Abstract: An optical extending device for use in transmission of optical signals which comprise at least one sequence of periodic optical signals, said optical device comprising: a first fiber optic having a characteristic dimensional propagation coefficient equal to &bgr;1 and adapted to be connected to a single mode second fiber optic having a length equal to L0 and a characteristic dimensional propagation coefficient equal to &bgr;0, wherein Lp, the length of said first fiber optic is substantially equal to }[T2/II−L0*&bgr;0]/&bgr;1}*{1−MOD(L0/{T2/II−L0*&bgr;0]/g(b)}} and wherein: n is an integer 1, 2, 3 . . . and is selected in accordance L0, the length of the single mode second fiber optic; T is a time period of the periodic optical signals; and MOD is the remainder obtained from dividing 10 by {[T2/II−L0*&bgr;0]/&bgr;1}.

Abstract: A method, a system and a module are proposed for detecting and locating faults in an optical multi channel network composed of network nodes. The method includes assigning different sub-carrier pilot tones to a number of the nodes comprising Network Elements (NE), applying the different sub-carrier pilot tones to any signal added to the network via the respective nodes, checking presence of one or more of the sub-carrier pilot tones at one or more points of the network, and, based on results of the checking, locating a faulty section of the network in case a fault occurred.