Abstract: An exemplary method and optical network that provide optical network restoration using refreshed state tables are disclosed. The exemplary method for recovering from a failure in an optical network using refreshed switch state tables includes generating and storing connection information in switch state tables of associated optical switches that define optical link connections to be made in the event of a failure, monitoring whether a failure has occurred, and refreshing the switch state tables by continuing to generate and store connection information in the plurality of switch state tables that are associated with the plurality of optical switches of the optical network until the failure in the optical network is detected. Once the failure is detected, optical switching is automatically performed in the optical switches based on the lookup table connection information in the switch state tables that are associated with the optical switches.

Abstract: An approach for providing network management of a submarine cable network. A line terminating equipment monitors a plurality of physical connections of the submarine cable network. A network management module receives selectively an alarm signal from the line terminating equipment or network management system and reconfigures the submarine cable network based upon the received alarm signal. According to one embodiment of the present invention, the submarine cable network is a dense wave division multiplexing (DWDM) system.

Abstract: An all-optical system for regenerating a first optical signal carried in a first direction on an optical transmission medium and a second optical signal carried in a second direction on the optical transmission medium includes a bi-directional clock recovery loop and a bi-directional optical gate. The bi-directional clock recovery loop includes a first optical clock recovery circuit for recovering a first clock signal from the first optical signal and a second optical circuit for recovering a second clock signal from the second optical signal. The first and second optical circuits of the clock recovery loop share at least some common optical circuit elements. The bi-directional optical gate includes a first non-linear optical light mirror circuit for producing a first regenerated signal based on the first optical signal and the first clock signal and a second non-linear optical light mirror circuit for producing a second regenerated signal based on the second optical signal and the second clock signal.

Abstract: A system and method for sharing a spare channel among two or more optical ring networks that have a common span. A first optical cross-connect switch (OCCS) and a first OCCS controller are placed at one end of the span and a second OCCS and OCCS controller are placed at the other end of the span. The first OCCS and the first OCCS controller are coupled to a first ADM from each optical ring, and the second OCCS and the second OCCS controller are coupled to a second ADM from each optical ring. The first OCCS controller receives alarm indications from each ADM that it is coupled to that senses a ring failure. The second OCCS controller receives alarm indications from each ADM that it is coupled to that senses a ring failure.

Abstract: A method of monitoring performance of an optical communications system measures (i) sub-carrier signal-to-noise ratio, (ii) optical signal signal-to-noise ratio, and (iii) measuring optical signal bit error rate, and diagnoses a system component failure based upon measured sub-carrier signal-to-noise ratio, optical signal signal-to-noise ratio, and optical signal bit error rate.

Abstract: A method and system for transporting ancillary network data is provided. A sub-carrier modulation signal containing ancillary network data is superimposed on a high bit-rate data signal prior to transport over an optical link. The monitoring subcarrier signal is significantly lower in both frequency and amplitude than the main data signal so as to not impact reliable reception of the main data signal. A low-pass filter filters the sub-carrier modulation signal from the data signal. By demodulating the sub-carrier signal, the ancillary network data is recovered. The ancillary network data includes any combination of data type information related to different network elements. The recovered ancillary network data is useful for any network management purpose. Especially important applications include restoration, wavelength re-use and routing, and any other general network management operation.

Abstract: A method of and apparatus for reducing unwanted mixing products on multiplexed optical communications lines, based upon the dispersion characteristics of the particular optical transmission line, in which a plurality of optical carriers are transmitted at substantially equally spaced apart frequencies over an optical fiber. When an unwanted mixing product is detected, a set of carriers that can be involved in producing the unwanted mixing product is determined. A carrier of the set is selected based upon the dispersion characteristics of fiber, and the frequency of the selected is shifted to eliminate the unwanted mixing product.

Abstract: A plurality of optical cross-connect switches are freely interconnected to form a mesh type network. At least three of the optical cross-connect switches are switched to form a line-switched ring network, thereby forming a ring/mesh network. Simply by changing the switching logic of the optical cross-connect switches within the ring/mesh network, new rings can be created and existing rings can be modified, thereby providing a great deal of flexibility to make changes to the network as traffic patterns change without incurring hardware costs or significant network downtime. Another advantage of the ring/mesh design approach is that spare capacity within the line-switched ring can be utilized by the mesh network, and spare capacity within the mesh network can be utilized by the line-switched ring, thereby significantly increasing the spare efficiency.

Abstract: A method and apparatus are provided for high signal-to-noise ratio (SNR) optical subcarrier management and reception in a communication network. In a multiple-wavelength optical communications link, ancillary signals that are conveyed by low-level intensity-modulated subcarriers are received with increased sensitivity in the subcarrier channel of the network. An increased SNR is accomplished by passing the same ancillary signal along all the carriers and by combining the received signals at a summing amplifier in the electrical domain.

Abstract: A dual-band optical amplifier uses a single pump source, such as a YAG solid-state laser emitting a pump light at a wavelength of 1047 nm, to provide amplification in both the 1550 nm and 1310 nm bands which are commonly encountered in the optical telecommunications environment. The pump light is fed into a fiber doped with praseodymium fluoride having Pr atoms in a +3 ionization state. These ions exhibit a ground state absorption that includes the 1047 nm wavelength. The same pump light is also coupled to a separate amplification fiber doped with trivalent erbium ions and ytterbium. This combination of ions also can be pumped to a metastable excited state by a 1047 nm wavelength source. Accordingly, when photon emission is generated, there is signal amplification in both fibers results.

Abstract: A system, method and apparatus are described that allow for the updating and transmittal of a low data rate signal providing ancillary network data as a rider on a high data rate optical signal. This subcarrier modulated signal can be processed and updated by using a drop/insert facility without having to alter the high data rate signal component of the data signal. Since the subcarrier signal can be detected by inexpensive equipment without having to detect and demultiplex the high data rate signal, the approach described offers a cost effective solution to the problem of network monitoring. Ancillary network management information can be communicated regardless of the quality or loss of the high data rate signal. In addition, by updating the subcarrier signal rider in a cumulative manner, a complete history of the fiber link the modulated optical signal travels on is provided to network management.

Abstract: A stable switched multifrequency source is described. The stable switched multifrequency source includes a narrowband reflective optical filter bank. This bank includes a plurality of narrowband reflective optical filter devices. In one embodiment, the stability and precision of the reflectivity of the narrowband reflective optical filter devices is further enhanced through regulation via temperature and/or bias current based on a comparison of the output wavelength and a precise stable wavelength reference. The stable switched multifrequency source also includes an optical switch that is coupled to each of the narrowband reflective optical filter devices.

Abstract: A method of and system for detecting and reporting faults in an all-optical communications system. The system monitors each of the optical fibers and uses the optical supervisory channel system to detect and report faults. Whenever the system detects a fault in any of optical fibers, the system forms a message identifying the fault and transmits the message in the optical supervisory channel carried by at least one of the optical fibers.

Abstract: A self-healing optical network carrying traffic between first and second optical linear terminals. The self-healing optical network including first, second, and third optical switching units, first, second, and third spare optical channels, and a working optical channel. The first, second, and third optical switching units are coupled in a ring configuration using said first, second, and third spare optical channels. The first and second optical switching units are coupled by the first spare optical channel and by the working optical channel. The first and second optical switching units each direct the traffic between the first and second optical linear terminals along the working optical channel or along the second and third spare optical channels in the event the working optical channel is not available.

Abstract: A polarization beam splitter separates the optical data signal into first and second orthogonally polarized optical signals. A first variable time delay element provides a first incremental propagation delay for the first polarized optical signal. A second variable time delay element provides a second incremental propagation delay for the second polarized optical signal. The first and second variable time delay elements consist of a series of optical switches optically interconnected by different incremental lengths of optical fiber. For example, 2.times.2 optical switches are provided for switching between a reference fiber segment and a respective delay fiber segment to provide a relative incremental propagation delay. A controller controls optical switches in the first and second variable switching delay elements to set first and second incremental propagation delays.

Abstract: A polarization mode compensation system and method using optical switch elements to establish incremental delays between different polarization modes of an optical data signal is provided. A polarization mode separator separates the optical data signal into first and second orthogonally polarized optical signals. A first variable switching delay element provides a first incremental propagation delay for the first polarized optical signal. A second variable switching delay element provides a second incremental propagation delay for the second polarized optical signal. The first and second variable switching delay elements consist of a series of optical switches optically interconnected by different incremental lengths of optical fiber. For example, 2.times.2 optical switches are provided for switching between a reference fiber segment and a respective delay fiber segment to provide a relative incremental propagation delay.

Abstract: A system and method for photonic facility and line protection switching in an optical network to permit fault tolerant operation. The optical network comprises components whose operation is monitored by a controller. If the controller determines an optical transmission line in a signal path has failed, the controller will re-route the signal path through a spare, or protect component. Alternatively, the controller can re-route the signal path through a frequency translator and another optical transmission line.

Abstract: A system and method for photonic facility and line protection switching in an optical network to permit fault tolerant operation. The optical network comprises components whose operation is monitored by a controller. If the controller determines a component in a signal path has failed, the controller will re-route the signal path through a spare, or protect, component.

Abstract: An optical interface device dynamically reconfigures a telecommunications network. The device includes an optically switched backplane connected between two stages of an optical tapped amplifier. Various modules may be plugged into the backplane for performing selective processing of the optical signal without any signal conversion to electrical domain. The modules are electrically controlled by a controller, which is also a module, overseeing the operations upon the optical signal by other modules.

Abstract: A system and method for multi-wavelength modulated optical communication uses the same optical fiber without the use of multiple tuned lasers. A transmitter includes an optical comb generator and a digital modulator. The optical comb generator generates a broad spectrum of wavelengths using a white noise generator. A Fabry-Perot cavity filters the wavelengths to form a set of equally spaced resonances lambda-1 . . . lambda-n. The comb generator is locked to a particular wave length by comparing each carrier or the composite mean of the carriers to an optical reference. An error signal is generated and fed back into the into comb generator. The resonances are split into n-channels using a tree splitter. Each channel is modulated in the digital modulator. The channels are summed as an optical signal and amplified to ensure proper power levels prior to being fed to an optical fiber.