Abstract: An upgradable optical router for use in an optical switching network. In an initial configuration, the optical router includes wavelength selective switches configured to switch optical signals having WDM wavelengths positioned in a grid having exactly 100 GHz (about 0.8 nm) spacing in optical frequency, aka fixed grid. The interface ports within the optical switch include an optical splitter and optical coupler and additionally space for a second selective switch. At a later point in time, a second wavelength selective switch can be added to provide additional capabilities such as switching wavelengths positioned in a flexible grid.

Abstract: A network protection switching mechanism comprises a plurality of optical switches located at a plurality of nodes; a plurality of optical communication paths between said switches; switch based fault detectors located as part of at least two switches which generate detection results representative of the identification of a fault; switch based controllers located as part of said at least two switches; and internal switch-communication means between said fault detectors and said controllers which facilitate the transmission of detection results from said fault detectors to said controllers; wherein said controllers directly cause switching to an alternative optical communication path dependent upon the receipt of said detection results; whereby autonomous switch based protection without dependence on either inter-switch control communication or higher level network control communication is achieved.

Abstract: A network protection switching mechanism comprises a plurality of optical switches located at a plurality of nodes; a plurality of optical communication paths between said switches; switch based fault detectors located as part of at least two switches which generate detection results representative of the identification of a fault; switch based controllers located as part of said at least two switches; and internal switch-communication means between said fault detectors and said controllers which facilitate the transmission of detection results from said fault detectors to said controllers; wherein said controllers directly cause switching to an alternative optical communication path dependent upon the receipt of said detection results; whereby autonomous switch based protection without dependence on either inter-switch control communication or higher level network control communication is achieved.

Abstract: A method for transmitting an optical response signal from a repeater to a terminal requesting status information pertaining to the repeater. In accordance with the method, in response to a command signal, a bias current applied to a laser pump within the repeater is modulated such that the laser pump generates modulated optical output power. The said modulation reflects the status information that is requested. An average value of the bias current applied to the laser pump is reduced while the bias current is being modulated. The modulated optical output power is applied to a doped optical fiber located within the repeater to amplitude modulate a communication signal traversing the doped optical fiber. A portion of the amplitude modulated communication signal is directed to the requesting terminal. The portion of the amplitude modulated communication signal may be received to detect a response signal embodied in the amplitude modulation.

Abstract: A method is provided for locating an intermittent fault occurring in an optical transmission system that includes a plurality of repeaters extending along first and second optical transmission paths for supporting bi-directional communication. In accordance with the method, a measurement is obtained of the gain imparted to a test signal along a round trip path between its originating point and each repeater. For each repeater there are identified changes in gain beyond a prescribed threshold and the time when the gain changes occur. A record of transmission performance data occurring over time is received. The performance data may be a bit error rate, SONET overhead data, or forward error correcting metrics, for example. For each repeater, a correlation in time is established between the identified gain changes and the transmission performance data. A fault location is identified based on the established correlation.