Abstract: The present invention relates to an optical communication network and to a network element for use in such a network. The network element comprises a plurality of receivers (70-76) for receiving optical communication signals, a plurality of transmitters (54-62, 82-86) for transmitting optical communication signals, and a plurality of network connections, each network connection having an individual signal impairment characteristic. The pluralities of receivers (70-76) and transmitters (54-62, 82-86) are adapted to employ a plurality of different modulation schemes (64, 66). Furthermore, the pluralities of receivers (70-76) and transmitters (54-62, 82-86) are assigned to the network connections as a function of the individual signal impairment characteristics.

Abstract: A method of transmitting digital signals over an optical transmission system is described. The method comprises the following steps: generating a signal according to the differential phased shift keying (DPSK) format, forwarding the DPSK signal to an optical delay filter, and using an output signal of the optical delay filter as a signal according to the phase shaped binary transmission (PSBT) format.

Abstract: A method of transmitting digital signals over an optical transmission system is described. The method comprises the following steps: generating a signal according to the non-return-to-zero (NRZ) format, forwarding the NRZ signal to an optical delay filter, and using an output signal of the optical delay filter as a signal according to the modified duobinary return-to-zero (MD-RZ) format.

Abstract: The present invention relates to an optical communication network and to a network element for use in such a network. The network element comprises a plurality of receivers (70-76) for receiving optical communication signals, a plurality of transmitters (54-62, 82-86) for transmitting optical communication signals, and a plurality of network connections, each network connection having an individual signal impairment characteristic. The pluralities of receivers (70-76) and transmitters (54-62, 82-86) are adapted to employ a plurality of different modulation schemes (64, 66). Furthermore, the pluralities of receivers (70-76) and transmitters (54-62, 82-86) are assigned to the network connections as a function of the individual signal impairment characteristics.

Abstract: A device for compensating the polarization dispersion suffered by an optical signal when it is transmitted by an optical line includes a polarization controller. It generates a differential time delay between two orthogonal polarization modes and controls the polarization controller so that it converts the signal transmitted by the line into a compensated optical signal. If the quality of the compensated optical signal remains below a reference quality the device modifies the state of polarization of the optical signal. Applications include long distance optical transmission via standard fibers.

Abstract: To increase the bit rate at which and the distance over which data can be transmitted by optical fiber, polarization dispersion is compensated by means of a polarization controller, a system for generating a differential group delay between two orthogonal modes of polarization and a control unit of the polarization controller. A chromatic dispersion compensator applies compensation which is adjusted dynamically to optimize the quality of the received optical signal. Applications include long-haul optical transmission on standard fibers.

Abstract: The invention disclose a device an a method for compensation of polarization mode dispersion comprising following steps: Measuring the degree of polarization of a signal at the receiver, Running an algorithm to find the maximum of degree of polarization, Comparing the degree of polarization with reference values of the compensation system in a data base, Switching the new starting point to the opposite side of the Poincare Sphere, when the reference value is under a definite threshold value and Selecting the new starting point from the data base.

Abstract: A method and a device for compensating the polarization mode dispersion (PMD) of a transmitted optical signal comprise means of a polarization controller (3) coupled to a differential group delay (DGD) generator (5). The polarization controller (3) is controlled by a feedback loop, said feedback loop implementing an optimisation algorithm to optimize a feedback parameter of the output signal of the DGD generator (5). The algorithm takes into account the state of polarization (SOP) of an optical signal determined from the output signal of the polarization controller (3)) or from the output signal from the DGD generator (5).

Abstract: A device for compensating the polarization dispersion suffered by an optical signal when it is transmitted by an optical line includes a polarization controller. It generates a differential time delay between two orthogonal polarization modes and controls the polarization controller so that it converts the signal transmitted by the line into a compensated optical signal. If the quality of the compensated optical signal remains below a reference quality the device modifies the state of polarization of the optical signal. Applications include long distance optical transmission via standard fibers.

Abstract: A differential group delay generator includes a polarization splitter which splits an input signal into two components having orthogonal states of polarization, and an adjustable delay system for receiving one component. For high accuracy and a fast response, the adjustable delay system includes an adjustable phase modulator for applying phase modulation to the carrier wave of the component to supply an intermediate signal carried by a modified center wavelength, and a delaying dispersive component receiving the intermediate signal and supplying a delayed signal. Applications include polarization dispersion compensation in long-haul optical transmission, especially via standard fibers.

Abstract: A method and a device for compensating the polarization mode dispersion (PMD) of a transmitted optical signal comprise means of a polarization controller (3) coupled to a differential group delay (DGD) generator (5). The polarization controller (3) is controlled by a feedback loop, said feedback loop implementing an optimisation algorithm to optimize a feedback parameter of the output signal of the DGD generator (5). The algorithm takes into account the state of polarization (SOP) of an optical signal determined from the output signal of the polarization controller (3)) or from the output signal from the DGD generator (5).