Abstract: A method and apparatus for providing signaling for disjoint shared protection in a data network are presented. In a preferred embodiment the method utilizes one or more of the same set of finite optical signals used for maintenance purposes in the network, which can be recognized without regard to bit rate or format. Nodes that share a failed link send an alarm signal that reaches the initiator and terminator node, whereupon the initiator node sends a signal that activates a protection lightpath. When the signal sent by the initiator node arrives at the terminator node, it sends back an acknowledge signal. If the acknowledge signal is not received within a certain time protection is voided. Contention for shared protection resources is resolved via a priority scheme.

Abstract: A single device for amplifying and multiplying an optical signal is presented. The device is an InP-semiconductor-based amplified multimode interferometer. The three main sections of the device are an input port, an interference and amplification region and N output ports. The input port is a single channel waveguide. The interference and amplification section supports a large number of modes which interfere with one another. By carefully choosing the length of the interference/amplification region to correspond to the constructive interference condition for N equally spaced channel modes, we can reproduce N amplified signals. In an alternate embodiment, by shaping the gain region into a cross pattern, corner reflections and consequent side channel signal distortion in the output can be minimized.

Abstract: A method and apparatus for a tunable optical spectrum analyzer that can measure the optical spectrum of a demultiplexed DWDM signal are presented. The signal level and Optical Signal to Noise Ratio (OSNR) of an individual channel of the DWDM signal can be obtained from the measured optical spectrum. The device employs a rapid tuning and detection technique to obtain the optical spectrum of the incoming signal. In a preferred embodiment the apparatus is fabricated on a single chip resulting in a compact measurement device. Using the device of the preferred embodiment, single channel OSNR can be determined in as small a time interval as approximately 225 microseconds. Using an array of these devices an entire DWDM mixed signal can be monitored as to OP and OSNR in the same time interval.

Abstract: A method and circuit are presented for the all optical recovery of the clock signal from an arbitrary optical data signal. The method involves two stages. A first stage preprocesses the optical signal by converting a NRZ signal to a PRZ signal, or if the input optical signal is RZ, by merely amplifying it. In a preferred embodiment this stage is implemented via an integrated SOA in each arm of an asymmetric interferometric device. The output of the preprocessing stage is fed to a clock recovery stage, which consists of a symmetric interferometer that locks on to the inherent clock signal by using the second stage input signal to trigger two optical sources to self oscillate at the clock rate. In a preferred embodiment the second stage is implemented via SOAs integrated in the arms of an interferometer, with two DFB lasers as terminuses. The output of the interferometer is an optical clock signal at the clock rate of the original input.

Abstract: A method and circuit are presented for the all optical recovery of the clock signal from an arbitrary optical data signal. The method involves two stages. A first stage preprocesses the optical signal by converting a NRZ signal to a PRZ signal, or if the input optical signal is RZ, by merely amplifying it. In a preferred embodiment this stage is implemented via an integrated SOA in each arm of an asymmetric interferometric device. The output of the preprocessing stage is fed to a clock recovery stage, which consists of a symmetric interferometer that locks on to the inherent clock signal by using the second stage input signal to trigger two optical sources to self oscillate at the clock rate. In a preferred embodiment the second stage is implemented via SOAs integrated in the arms of an interferometer, with two DFB lasers as terminuses. The output of the interferometer is an optical clock signal at the clock rate of the original input.

Abstract: A method and circuit are presented for the all optical recovery of the clock signal from an arbitrary optical data signal. The method involves two stages. A first stage preprocesses the optical signal by converting a NRZ signal to a PRZ signal, or if the input optical signal is RZ, by merely amplifying it. In a preferred embodiment this stage is implemented via an integrated SOA in each arm of an asymmetric interferometric device. The output of the preprocessing stage is fed to a clock recovery stage, which consists of a symmetric interferometer that locks on to the inherent clock signal by using the second stage input signal to trigger two optical sources to self oscillate at the clock rate. In a preferred embodiment the second stage is implemented via SOAs integrated in the arms of an interferometer, with two DFB lasers as terminuses. The output of the interferometer is an optical clock signal at the clock rate of the original input.

Abstract: A method and circuit are presented for the all optical recovery of the clock signal from an arbitrary optical data signal. The method involves two stages. A first stage preprocesses the optical signal by converting a NRZ signal to a PRZ signal, or if the input optical signal is RZ, by merely amplifying it. In a preferred embodiment this stage is implemented via an integrated SOA in each arm of an asymmetric interferometric device. The output of the preprocessing stage is fed to a clock recovery stage, which consists of a symmetric interferometer that locks on to the inherent clock signal by using the second stage input signal to trigger two optical sources to self oscillate at the clock rate. In a preferred embodiment the second stage is implemented via SOAs integrated in the arms of an interferometer, with two DFB lasers as terminuses. The output of the interferometer is an optical clock signal at the clock rate of the original input.

Abstract: A novel solution to fast network restoration is provided. In a network node, dedicated hardware elements are utilized to implement restoration, and these elements are linked via a specialized high speed bus. Moreover, the incoming and outgoing optical signals to each input/output port are continually monitored and their status communicated to such dedicated hardware via the high-speed bus. This provides a complete snapshot in virtually real time of the state of each input port on the node, and the switch map specifying the inter portal connections, to the dedicated control and restoration hardware. The specialized hardware detects trouble conditions and reconfigures the switching fabric. The invention enables a very fast and efficient control loop between the I/O ports, switch fabrics, and controllers.

Abstract: A method and system for AO3R functionality is presented. The system includes an AO2R device followed by an AOCR clock recovery module and an AOR retiming device. The AOR retiming device takes as input a recovered clock signal extracted from the output of the AO2R by the AOCR clock recovery module. The output is the recovered clock signal gated by the regenerated and reshaped input signal, and a monitor circuit is used to set the optimum operations of the retiming device. In a first embodiment the output of the AOR retiming device is fed to an AOC code and wavelength conversion output stage, which returns the signal to the NRZ coding, on a service wavelength converted to match the fixed wavelength connection with the DWDM transmission system. In a second embodiment the code conversion is incorporated into the AOR retiming device, and wavelength conversion is accomplished in the AOCR clock recovery device.

Abstract: A method and apparatus for a tunable optical spectrum analyzer that can measure the optical spectrum of a demultiplexed DWDM signal are presented. The signal level and Optical Signal to Noise Ratio (OSNR) of an individual channel of the DWDM signal can be obtained from the measured optical spectrum. The device employs a rapid tuning and detection technique to obtain the optical spectrum of the incoming signal. In a preferred embodiment the apparatus is fabricated on a single chip resulting in a compact measurement device. Using the device of the preferred embodiment, single channel OSNR can be determined in as small a time interval as approximately 225 microseconds. Using an array of these devices an entire DWDM mixed signal can be monitored as to OP and OSNR in the same time interval.

Abstract: In a maintenance system for a switch fabric in an optical switching network, a test signal is generated and multiplexed with the incoming traffic signal to form a composite signal. The composite signal is transmitted through the switch fabric via the traffic channel and then demultiplexed back into the traffic signal and the test signal, both of which are monitored by one or optical performance monitors. Thus, if the traffic signal is found to be defective, it is easy to determine whether the cause is the switch fabric or the incoming optical traffic signal that was already bad before entering the switch fabric.

Abstract: A method and circuit are presented for the all optical recovery of the clock signal from an arbitrary optical data signal. The method involves two stages. A first stage preprocesses the optical signal by converting a NRZ signal to a PRZ signal, or if the input optical signal is RZ, by merely amplifying it. In a preferred embodiment this stage is implemented via an integrated SOA in each arm of an asymmetric interferometric device. The output of the preprocessing stage is fed to a clock recovery stage, which consists of a symmetric interferometer that locks on to the inherent clock signal by using the second stage input signal to trigger two optical sources to self oscillate at the clock rate. In a preferred embodiment the second stage is implemented via SOAs integrated in the arms of an interferometer, with two DFB lasers as terminuses. The output of the interferometer is an optical clock signal at the clock rate of the original input.