Abstract: A method for designing a first optical filter, exhibiting a first filter performance satisfying a first preset criterion, and a second optical filter, exhibiting a second filter performance satisfying a second preset criterion, includes providing initial first and second filter designs for the first and second optical filters, respectively, as first and second ordered stacks of layers, respectively. A pair of layers, including a first layer, characterized by a first thickness, and a second layer, characterized by a second thickness, is selected from the first and second ordered stacks of layers. The first thickness is constrained to a first constrained thickness that is a positive integer multiple of the second thickness to yield a constrained first filter design. A predicted performance of the constrained first filter design is determined and compared with the first preset criterion for one of accepting and rejecting the constrained first filter design.

Abstract: A method for designing a first optical filter, exhibiting a first filter performance satisfying a first preset criterion, and a second optical filter, exhibiting a second filter performance satisfying a second preset criterion, includes providing initial first and second filter designs for the first and second optical filters, respectively, as first and second ordered stacks of layers, respectively. A pair of layers, including a first layer, characterized by a first thickness, and a second layer, characterized by a second thickness, is selected from the first and second ordered stacks of layers. The first thickness is constrained to a first constrained thickness that is a positive integer multiple of the second thickness to yield a constrained first filter design. A predicted performance of the constrained first filter design is determined and compared with the first preset criterion for one of accepting and rejecting the constrained first filter design.

Abstract: The present invention provides an optically-amplified bidirectional optical adddrop multiplexer for a bidirectional WDM optical communication system including two counterpropagating WDM optical signals. Each counterpropagating WDM signal enters the bidirectional add-drop multiplexer and is placed on an optical path, which does not include the other WDM optical signal. Each WDM optical signal may be amplified and have one or more optical channels added to or dropped from the respective signal. In an exemplary embodiment, one of the bidirectional WDM signals includes optical channels located in the C-band of an EDFA while the other bidirectional WDM signal includes optical channels located in the L-band of and EDFA. In this manner, an optical amplifier particularly selected for channels in a particular gain region may separately amplify each the separated bidirectional WDM signals. Each counterpropagating WDM signal exits the bidirectional add-drop multiplexed and rejoins the 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 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 a bidirectional optical network including an optical bridge for selectively transferring optical channels between two bidirectional wavelength division multiplexed optical communication systems. Two counterpropagating 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 counterpropagating 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 an optically-amplified bidirectional optical add-drop multiplexer for a bidirectional WDM optical communication system including two counterpropagating WDM optical signals. Each counterpropagating WDM signal enters the bidirectional add-drop multiplexer and is placed on an optical path, which does not include the other WDM optical signal. Each WDM optical signal may be amplified and have one or more optical channels added to or dropped from the respective signal. In an exemplary embodiment, one of the bidirectional WDM signals includes optical channels located in the C-band of an EDFA while the other bidirectional WDM signal includes optical channels located in the L-band of and EDFA. In this manner, an optical amplifier particularly selected for channels in a particular gain region may separately amplify each the separated bidirectional WDM signals. Each counterpropagating WDM signal exits the bidirectional add-drop multiplexed and rejoins the bidirectional optical waveguide.

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 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.