Abstract: An optical control system is described which is capable of maintaining and optimizing a fiber-optic transport system within it's domain of control while interacting with other optical systems which are controlled independently. This allows the optical system to be incorporated as a building block into a larger optical network in a relatively arbitrary fashion. This provides an underlying control system for a non-linear system like optics network that is flexible and extensible.

Abstract: An optical control system is described which is capable of maintaining and optimizing a fiber-optic transport system within it's domain of control while interacting with other optical systems which are controlled independently. This allows the optical system to be incorporated as a building block into a larger optical network in a relatively arbitrary fashion. This provides an underlying control system for a non-linear system like optics network that is flexible and extensible.

Abstract: Optical performance monitoring of a dense wave division multiplex optical communication system is immune to effects of stimulated Raman scattering. Each wavelength is modulated by an orthogonal spreading code dither signal having a predetermined modulation index. At a receiver, a portion of the aggregate optical signal is tapped and passes through a wavelength dependant optical delay filter. For each wavelength, the aggregate signal is multiplied by a synchronized copy of a respective spreading code and an autocorrelator detects the modulation power of the spreading code dither. The system can also be deployed as an optical reflectometer. For each autocorrelator, an aggregate reflected signal is multiplied by a copy of a spreading code having a respective different time delay. The distance to a reflection can be estimated from the time delay that yields the highest autocorrelation value.

Abstract: In a method and apparatus for measuring and controlling signal gain of a backward Raman amplifier having multiple pump lasers as used in optical communications networks, Raman pump power levels required to provide a uniform gain across a range of wavelengths in an optical fiber are determined by a combination of theoretical calculations and empirical measurement. A system of non-linear differential equations is solved for various pump powers and used to build a look-up table relating desired average Raman gain to the normalized power required to provide a uniform gain across a range of wavelengths. The linear relationship between Raman pump power and average Raman gain is determined by measuring data signal power levels at specific Raman pump powers. A desired average Raman gain is first applied to the linear relationship to determine total power required, and then applied to the look-up table to determine the required relative pump powers.

Abstract: In method of controlling an optical amplifier dynamically adapts to both configuration and performance changes of a communications system. An error vector is calculated to indicate a difference between respective detected values and target values of a parameter of a light beam downstream of the optical amplifier. A sensitivity matrix indicative of a sensitivity of the detected parameter value to incremental changes in a control variable of the optical amplifier is calculated. A predicted optimum value of the control variable is then calculated using the error vector and the sensitivity matrix. Calculation of the predicted optimum control variable value can be iterative, with the sensitivity matrix calculated either during each iteration, or at the beginning of each optimization run. As a result, optimization of the amplifier control variables is performed based on a sensitivity matrix that accurately reflects the performance of the amplifier.

Abstract: The present invention relates to a method and apparatus for system level Stimulated Raman Scattering (SRS) error compensation in an optical fiber network, the network characterized in that it comprises the infrastructure required to measure the power levels of all optical channels using a pilot tone monitoring technique, the compensation method comprises the steps of collecting preceding fiber span system configuration data such as, but not necessarily limited to, the power level of each wavelength and wavelength distribution, SRS error up to that point, fiber type and insertion loss, transmitting the configuration data to a network component having computer readable-code adapted to receive the configuration data, calculating local SRS error values incorporating the transmitted configuration data and leveraging the calculated local SRS error values to correct power levels based on the reported SRS error of the previous spans and the local SRS error.

Abstract: In a method and apparatus for measuring and controlling signal gain of a backward Raman amplifier having multiple pump lasers as used in optical communications networks, Raman pump power levels required to provide a uniform gain across a range of wavelengths in an optical fiber are determined by a combination of theoretical calculations and empirical measurement. A system of non-linear differential equations is solved for various pump powers and used to build a look-up table relating desired average Raman gain to the relative pump powers required to provide a uniform gain across a range of wavelengths. The linear relationship between Raman pump power and average Raman gain is determined by measuring data signal power levels at specific Raman pump powers. A desired average Raman gain is first applied to the linear relationship to determine total power required, and then applied to the look-up table to determine the required relative pump powers.

Abstract: Iterative approach to Stimulated Raman Scattering (SRS) error estimation in an optical fiber network comprised of determining a multi-channel SRS error value for each pairing of all possible pairings of all the channels by inputting measured channel power levels into a two-channel equation and further calculating the SRS error in a single fiber span for all channels by extending the two-channel equation in an iterative form for calculating the SRS error in a single fiber span for all channels. An embodiment of the invention further comprising determining for each channel over multiple fiber spans the amount of total SRS error value at every span based on the calculated SRS error value of its previous span to determine the SRS error accumulated over a multi-span network.

Abstract: The present invention relates to higher order effects in Stimulated Raman Scattering (SRS) error estimation in an optical fiber network, the network characterized in that it comprises the infrastructure required to measure the power levels of all optical channels using a pilot tone monitoring technique, the estimation comprising the steps of determining the multi-channel SRS error value by applying small signal analysis to the solution of the SRS system of differential equations, calculating the SRS error in a single fiber span for all channels by creating a Dither Transfer Matrix (DTM) and estimating SRS by observing higher order effects within the DTM.

Abstract: The present invention relates to a method and apparatus for system level Stimulated Raman Scattering (SRS) error compensation in an optical fiber network, the network characterized in that it comprises the infrastructure required to measure the power levels of all optical channels using a pilot tone monitoring technique, the compensation method comprises the steps of collecting preceding fiber span system configuration data such as, but not necessarily limited to, the power level of each wavelength and wavelength distribution, SRS error up to that point, fiber type and insertion loss, transmitting the configuration data to a network component having computer readable-code adapted to receive the configuration data, calculating local SRS error values incorporating the transmitted configuration data and leveraging the calculated local SRS error values to correct power levels based on the reported SRS error of the previous spans and the local SRS error.