Abstract: The present invention provides a wavelength division multiplexed optical communication system including an optical fiber ring configured to carry at least one wavelength division multiplexed optical communication signal having plural optical channels at different wavelengths. Optical amplifiers are interposed along the optical fiber ring for optically amplifying the wavelength division multiplexed optical communication signal. Each optical amplifier produces amplified spontaneous emission as well as amplifying the optical channels of the WDM signal. At each amplifier, amplified spontaneous emission is selected by an optical feedback selector and is fed back to the optical amplifier input via an optical feedback path; the created wavelength travels along the ring and is dropped near the input of the next adjacent amplifier, reducing ASE in the optical fiber ring.

Abstract: The present invention relates to an optical network including a bridge for selectively transferring information from an optical channel carried on a first WDM optical waveguide to at least two optical channels on a second WDM optical waveguide. The first and second optical waveguides carry WDM optical signals each having plural optical channels. A bridge is interposed between the first and second optical waveguides which includes an optical add-drop multiplexer optically communicating with each waveguide. At least one optical channel having first and second data bits streams is dropped from the first waveguide. The first and second data bit streams are respectively encoded on two different optical channels which are then added to the second optical waveguide.

Abstract: The present invention improves the performance of optical networks, particularly optical ring networks, by reducing amplified spontaneous emission thereby increasing the available gain of optical amplifiers within that network. In one embodiment, the invention provides a WDM optical communication system having an optical fiber ring with optical fiber amplifiers interposed along the ring. An optical wavelength is injected into the optical fiber ring at a first location; the optical wavelength is selected to be located within a region of amplified spontaneous emission for the optical fiber amplifier. The optical wavelength is dropped from the optical fiber ring at a second location positioned such that the injected optical wavelength is dropped at or prior to returning to the first location within the ring. The optical wavelength passes through at least two of the plurality of optical amplifiers before being dropped from the optical fiber ring.

Abstract: The present invention relates to a bidirectional optical network including a bridge for selectively transferring information from an optical channel carried on a first bidirectional WDM optical waveguide to at least two optical channels on a second bidirectional WDM optical waveguide. The first and second bidirectional optical waveguides each carry two counter-propagating WDM optical signals each having plural channels. A bridge is interposed between the first and second bidirectional optical waveguides which includes an optical add-drop multiplexer optically communicating with each bidirectional waveguide. At least one optical channel having first and second data bits streams is dropped from the first bidirectional waveguide. The first and second data bit streams are respectively encoded on two different optical channels which are then added to the second bidirectional optical waveguide.

Abstract: The present invention provides a bidirectional wavelength division multiplexed optical communication system having bidirectional optical service channels. The bidirectional WDM optical communication system includes a bidirectional optical waveguide configured to carry a bidirectional optical communication signal comprising counterpropagating WDM optical signals. Each WDM optical signal includes plural optical channels and an optical service channel. A bidirectional optical add-drop multiplexer optically communicates with the waveguide. A first optical service channel selector optically communicates with the first bidirectional optical add-drop multiplexer input/output port.

Abstract: The present invention provides a bidirectional wavelength division multiplexed optical communication network useful in numerous network configurations. The network includes a bidirectional optical waveguide carrying counter-propagating wavelength division multiplexed optical signals each including plural channels. Several optical nodes are positioned along the bidirectional optical waveguide, each of which includes an optically-amplified bidirectional optical add-drop multiplexer. Each bidirectional optical add-drop multiplexer includes channel selectors for selecting at least one optical channel from each of the counter-propagating WDM optical signals. Each optical node further includes at least one optical transmitter for supplying an optical channel to be added by the bidirectional optical add-drop multiplexer to the bidirectional optical waveguide and at least one optical receiver for receiving an optical channel dropped from the bidirectional optical waveguide by the bidirectional add-drop multiplexer.

Abstract: The present invention provides a bidirectional wavelength division multiplexed optical communication network having a protection switching capability within a bidirectional optical waveguide. A bidirectional optical waveguide having plural optical nodes carries counterpropagating wavelength division multiplexed optical communication signals: M optical channels in a first direction and N optical channels in a second direction. The network includes the capacity to generate X+Y protect optical channels which respectively propagate in the first and second directions. Upon detecting loss of an optical signal means are provided for switching the affected M work optical channels to the Y protect optical channels and the affected N work channels to the X protect channels. In this manner, protection switching may be accomplished in a bidirectional optical network on a single bidirectional optical waveguide.

Abstract: The present invention provides a system for protection switching in a wavelength division multiplexed optical communication network including optical transponders within optical nodes. A work optical transponder receives a first work optical channel dropped by an optical add-drop multiplexer from an optical waveguide while a second work optical transponder adds a work optical channel to the optical add-drop multiplexer. Similarly, a first protect optical transponder is positioned to receive a protect optical channel dropped by the optical add-drop multiplexer while a second protect optical transponder is positioned to add a protect optical channel to the optical add-drop multiplexer.

Abstract: The present invention provides a flexible WDM optical communication system in which each optical channel of the WDM optical communication signal can simultaneously accept multiple data formats. In one embodiment, the WDM optical system includes an optical waveguide having an optical add-drop multiplexer to selectively add and/or drop one or more optical channels to/from the WDM signal carried on the waveguide. A first source of data imparts information onto a first optical channel in a packet format while a second source of data imparts information onto the first optical channel in a time division multiplexed format. Other data sources having other data formats may also be included. An optical network interface electrically communicates with the data sources, placing the data from these sources onto the first optical channel which is generated from an optical source such as a laser. An optical path carries the optical channel from the optical source to the optical add-drop multiplexer.

Abstract: The present invention relates to a bidirectional optical network including an optical bridge for selectively transferring optical channels between two bidirectional wavelength division multiplexed optical communication systems. Two counter propagating WDM optical signals are carried on each bidirectional waveguide. An optical bridge is interposed between the bidirectional waveguides and includes an optical coupler and channel selector configured to select one or more optical channels from a first WDM optical signal and a second optical coupler and channel selector configured to select one or more optical channels from the counter propagating WDM optical signal. At least one optical path is positioned between the first bidirectional optical waveguide and the second bidirectional optical waveguide which carries at least the selected one or more first optical channels to an optical combiner interposed along the second bidirectional optical waveguide.

Abstract: The present invention provides bidirectional add-drop multiplexers for bidirectional wavelength division multiplexed optical communication systems. In a first configuration, the bidirectional add-drop multiplexer includes six three-port optical circulators. The bidirectional add-drop multiplexer is placed at any point along a bidirectional transmission waveguide configured to carry two counter-propagating wavelength division multiplexed optical signals. The bidirectional waveguide places the west-east wavelength division multiplexed optical signal into the first port of the first circulator where it is routed to the first port of the second optical circulator. A channel selector is positioned between the second and third optical circulators for add/dropping optical channels. The through channels and any added channels exit through the first port of the fourth circulator as a counter-propagating east-west WDM optical signal enters the first port.