Abstract: A method and apparatus for a monitoring technique for the rate of change of polarization state and of the polarization mode dispersion is proposed. This technique is used for performance monitoring and fault correlation as well as for the verification of commitments to customers with respect to the transmission system's tolerance to polarization mode dispersion.

Abstract: A method and system for high bit rate fiber-optic communications utilize a wavelength tunable transmitter controlled by a feedback signal from an error analyzer associated with a received optical data stream without utilizing a dispersion compensation module in the transmitter and/or receiver portion.

Abstract: A method and system for high bit rate fiber-optic communications utilize a wavelength tunable transmitter controlled by a feedback signal from an error analyzer associated with a received optical data stream.

Abstract: A method and apparatus for providing a supervisory channel in a wavelength division multiplexing (WDM) fiber-optic communication system uses a controlled optical attenuator disposed in an optical path between a demultiplexer (DMUX) and a multiplexer (MUX) of an Optical Add-Drop Multiplexer (OADM.

Abstract: A method and apparatus for a monitoring technique for the rate of change of polarization state and of the polarization mode dispersion is proposed. This technique is used for performance monitoring and fault correlation as well as for the verification of commitments to customers with respect to the transmission system's tolerance to polarization mode dispersion.

Abstract: A method and system for high bit rate fiber-optic communications utilize a wavelength tunable transmitter controlled by a feedback signal from an error analyzer associated with a received optical data stream without utilizing a dispersion compensation module in the transmitter and/or receiver portion.

Abstract: A method and system for high bit rate fiber-optic communications utilize a wavelength tunable transmitter controlled by a feedback signal from an error analyzer associated with a received optical data stream.

Abstract: A method and apparatus for providing a supervisory channel in a wavelength division multiplexing (WDM) fiber-optic communication system uses a controlled optical attenuator disposed in an optical path between a demultiplexer (DMUX) and a multiplexer (MUX) of an Optical Add-Drop Multiplexer (OADM.

Abstract: An optical fiber cable is tested to determine the zero dispersion frequencies of the sections of which it is made by directing light along it, the light comprising two optical frequency components having optical frequencies that differ by a predetermined amount ??. The frequencies of the components are swept across the operating frequency range of the cable, keeping ?? constant. At the other end of the cable, the spectrum of the light is analyzed to determine the relative powers of first order 4 WM components (satellite lines) and the frequencies at which they have principal maximum values.

Abstract: An optical fiber cable is tested to determine the zero dispersion frequencies of the sections of which it is made by directing light along it, the light comprising two optical frequency components having optical frequencies that differ by a predetermined amount ??. The frequencies of the components are swept across the operating frequency range of the cable, keeping ?? constant. At the other end of the cable, the spectrum of the light is analyzed to determine the relative powers of first order 4WM components (satellite lines) and the frequencies at which they have principal maximum values.

Abstract: Residual chromatic dispersion in an optical transmission system is measured and compensated by utilizing the bit error rate for the system. A predetermined amount of chromatic dispersion is introduced into receive end of the optical transmission system and the bit error rate is measured and associated with that predetermined amount of chromatic dispersion. The predetermined amount of chromatic dispersion is then changed to a new predetermined amount to reduce and, ultimately, minimize the bit error rate. Total residual chromatic dispersion is then measured as the complement of the predetermined amount of chromatic dispersion that corresponds to the minimum bit error rate. At least some portion of the residual chromatic dispersion is compensated by introducing a fixed amount of dispersion in a range from 0 ps/nm to and including the predetermined amount of chromatic dispersion that corresponds to the minimum bit error rate.

Abstract: A method and apparatus for increasing the operational bandwidth of a multimode optical fiber communications system is provided. The method comprises launching optical radiation into the core of the multimode fiber away from the center of the core so as to strongly excite mid order modes of the multimode fiber, but to only weakly excite low order and high order modes of the multimode fiber. The mid order modes excited are predominately within a small number of mode groups and thus have similar propagation constants. This leads to a reduction in modal dispersion and thus to a significant increase in bandwidth compared to an overfilled launch. The offset launch of the invention is tolerant both to the launch conditions and to any imperfections in the fiber refractive index profile. Modal noise performance is also enhanced. Embodiments of the invention employ a singlemode fiber, a multimode fiber or a lens to illuminate an end face of a multimode fiber with a small spot offset from the optical axis of the fiber.