Abstract: An optical interface device is provided for use in an undersea optical transmission system that includes an undersea optical transmission path, a plurality of optical repeaters located along the optical transmission path, and a selected one of any of a plurality of different vendor supplied optical transmission terminals each of which has a vendor-specific interface. The optical interface device includes a signal processing unit providing signal conditioning to optical signals received from the vendor-specific interface of the selected optical transmission terminal so that the optical signals are suitable for transmission through the undersea optical transmission path. A gain monitoring arrangement is also provided for determining a change in gain provided by any one of the optical repeaters.

Abstract: A method and apparatus is provided for obtaining status information concerning an optical transmission path. The method begins by generating a COTDR probe signal having a prescribed wavelength and transmitting optical traffic signals and the COTDR probe signal over an optical transmission path having a length corresponding to those used in regional undersea market applications. The prescribed wavelength of the COTDR probe signal is separated from wavelengths at which the optical traffic signals are located by a distance at least equal to a predetermined guard band. A backscattered and/or reflected portion of the COTDR probe signal in which status information concerning the optical path is embodied is received over the optical path. The backscattered and/or reflected portion of the COTDR probe signal is detected to obtain the status information.

Abstract: In an optical communication system that includes a transmitting terminal, a receiving terminal, and an optical transmission path optically coupling the transmitting and receiving terminals and having at least one rare-earth doped optical amplifier therein, a second optical amplifier is provided The second optical amplifier includes a first portion of the optical transmission path having a first end coupled to the transmitting terminal and a second end coupled to a first of the rare-earth doped optical amplifiers. In addition, the second optical amplifier includes a pump source providing pump energy to the first portion of the optical transmission path at one or more wavelengths that is less than a signal wavelength to provide Raman gain in the first portion at the signal wavelength.

Abstract: An undersea WDM optical transmission system is provided. The system includes first and second land-based cable stations, at least one of the cable stations includes power feed equipment (PFE) supplying electrical power to the cable at a voltage of no more than about 6 kv or less. The PFE is located in at least one of the cable stations. The system also includes an undersea WDM optical transmission cable having a length corresponding to those required in the undersea regional market. The cable includes at least one optical fiber pair for supporting bidirectional communication between the first and second cable stations. At least one repeater is located along the optical transmission cable. The repeater includes at least two optical amplifiers each providing optical gain to one of the optical fibers in the optical fiber pairs. The optical gain is in a range from about 12 to 20 dB.

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 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 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.