Abstract: A method and apparatus is provided for using optical time-domain reflectometry (OTDR) with a WDM transmission system that includes a plurality of terminals interconnected by at least two pairs of unidirectional optical transmission paths each of which has at least one repeater therein. The method begins by transmitting an optical probe signal from a first OTDR unit associated with a first terminal into the repeater over a first optical path in a first of the at least two pairs of unidirectional optical transmission paths. The first OTDR unit receives a first returned OTDR signal over a second optical path in the first optical path pair. The first OTDR signal contains status information concerning the first optical path in the first optical path pair. The optical probe signal from the first optical path in the first optical path pair is coupled to a second optical path in the second optical path pair.

Abstract: In a method and system for evaluating distributed gain in an optical transmission system, a data signal and a residual pump laser signal propagating in opposite directions within a waveguide are monitored. Modulation of the residual pump laser signal is correlated with low frequency components of the data signal. This correlation is used to determine cross-talk between the data signal pump laser signals, as a function of location within the waveguide. The distributed gain is then evaluated from the cross-talk, using a known relationship, or proportionality, between gain and cross-talk.

Abstract: An optical fiber selection system automatically recommends an appropriate optical fiber type for a communication network, based on input from a user. In one embodiment, the system includes a user computer system that is in communication with a vendor computer system. The vendor computer system executes code and performs a number of steps. Initially, the vendor computer system receives at least one technical parameter associated with the proposed communication network from the user, via the user computer system. Next, the vendor computer system automatically selects an optical fiber type for the communication network based on the least one technical parameter. Finally, the vendor computer system provides the selected optical fiber type to the user, via the user computer system.

Abstract: An optical fiber emulator. The emulator receives a digitally-encoded optical signal; demodulates the optical signal to produce serial electrical pulses representative of the digital signal; converts the serial pulses to parallel pulses; propagates the parallel pulses through a shift register whose propagation time is less than or equal to the time of a length of fiber to be emulated. The emulator then converts the parallel pulses at the output of the shift register to serial pulses; modulates an optical carrier with the serial pulses from the shift register; and attenuates the modulated optical signal an amount corresponding to the length of the fiber being emulated to produce an output optical signal whose propagation time is substantially equal to that of a section of optical fiber to be emulated. The shift register may be tapped at any point to obtain an output delayed by a desired amount corresponding to a selected section of optical fiber.

Abstract: The present invention is a non-coherent optical fiber apparatus that may be used for imaging. Methods are described to produce geometric mapping data for an optical fiber apparatus. Images may be transmitted, reconstructed (using mapping data for the apparatus) and displayed. In addition, one or more fiber characteristics may be measured and used in conjunction with mapping data to further improve or correct the geometric, photometric or spectral content of images. The apparatus data described may be provided, by a manufacturer, for example, in raw form, or this data may be may be provided in a manner that is more user transparent, such as incorporating it into various image processing algorithms.

Abstract: An optical communications system is adapted for connection to an optical fiber link of an optical communications network. The system obtains a fiber identifier respecting the optical fiber link; a respective optimum setting of one or more parameters of the optical communications system; and adjusts a respective value of each parameter in accordance with the respective optimum setting. The fiber identifier can be obtained from a value of at least one fiber transmission property of the optical fiber link. The fiber transmission property value is used to search a look-up table of class definitions, each class definition including a respective class identifier and at least one corresponding characteristic transmission property value. A class identifier is selected as the fiber identifier from the class definition for which each characteristic transmission property value most closely matches a corresponding fiber transmission property value.

Abstract: A method, and optical network management system is provided for monitoring an optical transmission system, including assigning a plurality of threshold values corresponding to a performance parameter associated with the optical transmission system. The method, and optical network management system further perform the step of identifying degradation of the optical transmission system based on which of the threshold values being exceeded.

Abstract: A method for designing an optical system is disclosed. The optical system launches optical signals modulated with data into a fiber link having a property of inducing nonlinear distortion of the optical signals as a function of signal power of the optical signals and distance traversed in the fiber link. A Q-factor curve for the fiber link is determined as a function of the signal power. A signal power is preselected based on the Q-factor curve. The preselected signal power is associated with a set of channels. A coding gain is preselected based on the preselected signal power and a desired channel spacing for the set of channels.