Abstract: A method and apparatus is provided for obtaining status information concerning an optical transmission path. The method begins by generating a cw probe signal having a frequency that is swept over a prescribed frequency range in a prescribed time period. The cw probe signal is transmitted over the optical path and a returned COTDR signal in which status information concerning the optical path is embodied is received over the optical path. A predetermined frequency is detected within the prescribed frequency range of the returned COTDR signal to obtain the status information.

Abstract: A method is provided for locating a fault arising in one or more optical amplifiers from among a plurality of optical amplifiers operating in saturation and located along an optical transmission path. The method begins by generating a COTDR trace representing a backscattered and/or reflected optical power level along the transmission path and comparing the COTDR trace to a previously obtained reference COTDR trace to generate a difference trace that represents a change in gain. The change in gain is assigned to at least one of the plurality of optical amplifiers based on the difference trace.

Abstract: A method and apparatus is provided for obtaining status information from a given location along an optical transmission path. The method begins by generating a cw probe signal having a prescribed frequency that is swept over a prescribed frequency range. The cw probe signal is transmitted over the optical path and a returned COTDR signal in which status information concerning the optical path is embodied is received over the optical path. A receiving frequency within the prescribed frequency range of the returned COTDR signal is detected to obtain the status information. The detecting step includes the step of sweeping the receiving frequency at a rate equal to that of the prescribed frequency. A period associated with the receiving frequency is temporally offset from a period associated with the prescribed frequency.

Abstract: A system, amplifier and method are provided for amplifying an optical signal in an optical communications system where spans between amplifiers may vary. The system includes a Raman amplifier variable gain portion and an EDFA gain portion. The amount of Raman amplifier gain is chosen to trade off accumulation of noise with accumulation of multi-path interference. This variable Raman gain is used to equalize the loss of each span so that the amount of optical power supplied at the input of the EDFA gain portion is substantially constant throughout the system.

Abstract: A method for entering a market with high barriers to entry and a plurality of proprietary business elements includes converting at least one of the business elements into a universal business element that can accept a wide variety of inputs from other business elements, while converting a remaining one of the plurality of business elements to commoditized business elements. For example, one exemplary embodiment of the present invention employs an optical repeater that can accept any existing submarine cable, in combination with an optical line interface terminal that can accept existing terrestrial terminal equipment. Regarding market division, this embodiment is specifically limited to spans of less than 5000 kilometers, and preferably between 350 and 4000 kilometers, thereby straddling both the long-haul and short-haul markets while providing highly desirable services and capability.

Abstract: In accordance with the present invention, a land-based cable station is provided for an undersea optical transmission system. The cable station includes submarine line terminal equipment (SLTE) for processing terrestrial traffic received from an external source, power feed equipment for supplying electrical power to active undersea components of the transmission system, an element management system for configuring and obtaining status information from the transmission system, and a cable termination box in which an undersea cable terminates. The SLTE includes terrestrial optical transmission equipment receiving the terrestrial traffic and generating optical signals in response thereto. The SLTE also includes an interface device providing signal conditioning to the optical signals received from the terrestrial optical transmission equipment so that the optical signals are suitable for transmission through the undersea optical transmission system.

Abstract: A branching unit is provided for interconnecting at least three undersea optical transmission cables. The branching unit includes first, second and third ports for receiving first, second and third undersea optical transmission cables, respectively. The first and second cables each include an electrical power conductor and a plurality of first optical fibers. The third cable is electrically unpowered and includes at least one drop optical fiber and at least one add optical fiber. An electrical power conductor segment is provided for electrically coupling the conductor in the first cable received in the first port to the conductor in the second cable received in the second port. A first optical fiber segment optically couples a first of the plurality of first optical fibers in one of the first or second cables to the drop optical fiber of the third cable.

Abstract: A method and apparatus is provided for monitoring optical signal quality between land-based terminal equipment and an undersea optical transmission path. The method begins by receiving an analog optical signal in which information is embodied in digital form from either of the terminal equipment or the undersea optical transmission path. The method continues by measuring a parameter such as the Q-factor, which reflects signal quality by analysis of the analog optical signal and not the information digitally embodied therein.