Abstract: An optical signal receiver including a plurality of threshold decision circuits configured to receive an electrical signal representative of the optical signal. Each of the threshold decision circuits is configured to sample the electrical signal and to provide an associated threshold decision circuit output in response to a comparison of the signal to an associated threshold level. The threshold decision circuit outputs are coupled to an output decision circuit, which is configured to output a signal representative of a binary state of the optical signal. An optical communication system and a method of reconstructing received data signal in an optical communication system are also provided.

Abstract: An optical communication system configured to operate with optical signals at lower signal to noise ratios than previously contemplated. The communication system includes a receiver having an optical pre-processor coupled between a demultiplexer and a detector. The optical pre-processor includes either an optical polarization section having a polarization rotator and an optical polarizer, a phase modulation section that includes a phase modulator and a dispersion element and a clock recovery circuit, or an amplitude modulation section that includes an amplitude modulator clock recovery circuit and a spectral shaping filter.

Abstract: The position and amount of localized polarization dependent anomalies such as polarization mode dispersion and/or polarization dependent loss may be measured by applying a polarization modulated probe signal to an optical transmission line. The polarization modulated probe signal is returned via optical feedback paths positioned along the line, and is detected by a probe signal receiver to identify the position and strength of the anomaly.

Abstract: Methods and apparatus of performing polarization control for optical transmissions. The methods and apparatus enable polarization control devices to achieve a desired output state of polarization regardless of the input state of polarization. The desired state of polarization can be achieved by rotating waveplates in a polarization controller in a sequential fashion. Each waveplate may be continually adjusted or dithered so long as the feedback signal satisfies a feedback condition. Once the feedback signal exceeds the feedback condition, the next waveplate in the polarization controller is adjusted. This enables the methods and apparatus to rapidly adjust the state of polarization away from dead spots and minimize loss control problems.

Abstract: A method of compensating for chromatic dispersion in an optical signal transmitted on a long-haul terrestrial optical communication system including a plurality of spans, including: allowing chromatic dispersion to accumulate over at least one of the spans to a first predetermined level; and compensating for the first pre-determined level of dispersion using a dispersion compensating fiber causing accumulation of dispersion to a second predetermined level. There is also provided a hybrid Raman/EDFA amplifier including a Raman portion and an EDFA portion with a dispersion compensating fiber disposed therebetween. An optical communication system and a method of communicating an optical signal using such a Raman/EDFA amplifier are also provided.

Abstract: A system and method for optimizing dispersion in an optical transmission line is provided. The system and method comprise measuring the amplitude of a d.c. voltage component of a synchronously demodulated data signal of at least one wavelength channel by an in-phase carrier at the baud frequency of the wavelength channel. In an alternative embodiment, the system and method comprise measuring the IF amplitude of the resulting a.c. signal of a data signal of the at least one wavelength channel comprising a received RZ signal mixed with a local oscillator, whose frequency differs from the wavelength channel baud by a relatively small amount, somewhere on the order of about 100 kHz.

Abstract: Embodiments of an apparatus for forming a WDM signal having orthogonally polarized optical channels are disclosed. Utilizing the optical channels formed using non-polarization-maintaining components, the apparatus selectively controls a state of polarization (SOP) of each optical channel.

Abstract: A hybrid Raman-EDFA provides gain equalization over the C-band and L-band. The hybrid Raman-EDFA includes a Raman section producing a Raman gain and an EDFA section producing an EDFA gain complementing the Raman gain. The EDFA section preferably includes a highly inverted, single-stage EDFA to produce the complementing EDFA gain shape. One embodiment of the EDFA section includes a high return loss termination located after the erbium fiber to receive unabsorbed pump power. Multiple hybrid Raman-EDFAs can be connected in an amplifier chain in a transmission system. The transmission system preferably provides a dispersion map including regular composite fiber spans followed by at least one compensating span of negative dispersion fibers. The Raman sections of the hybrid Raman-EDFAs are preferably coupled to negative dispersion fiber in the transmission system.

Abstract: A multiple hinged tray cable connecting joint includes a plurality of fiber trays pivotably coupled between sockets connected to fiber optic cables. The fiber trays can be positioned in a fiber loading position in which the fiber is spliced and coiled into the tray. The fiber trays can then be pivoted to a fiber storage position.

Abstract: An optical fiber cable includes pairs of transmission lines having length extensions and color coding to facilitate cable system assembly. Each transmission line is preferably constructed from unitary fibers including a P-type fiber and an N-type fiber with the length extensions of the same P-type and N-type fiber at each end respectively. The P-type fiber and the N-type fiber are preferably colored differently to indicate transmission direction. The P-type fiber and N-type fiber in one pair of transmission lines are preferably colored differently than the P-type fiber and N-type fiber in other pairs.

Abstract: A method and apparatus for performing error correction is described. A stream of data is encoded using concatenated error correcting codes. The encoded data is communicated over a transmission system. The encoded data is decoded using the codes and three levels of decoding.

Abstract: A wavelength division multiplex optical system includes a WDM combiner to provide a source signal, at least one transmitter coupled to an input of the WDM combiner, a broadband noise source, and a filter coupled between the broadband noise source and another input of the WDM combiner. In one embodiment, the filter is an optical notch filter. In an alternative embodiment, the filter includes a WDM demultiplexer coupled through plural filters to provide a plurality of noise signals and a WDM multiplexer coupled through at least one filter of the plural filters to respective noise signals.

Abstract: Embodiments of an apparatus for forming a WDM signal having orthogonally polarized optical channels are disclosed. Utilizing the optical channels formed using non-polarization-maintaining components, the apparatus selectively controls a state of polarization (SOP) of each optical channel.

Abstract: A method and apparatus for maintaining an established error count for data transmitted on a wavelength division multiplexed (WDM) optical communication network. Error counts from a forward error correction (FEC) code are monitored and operational parameters are automatically adjusted in response to the error counts, thereby achieving system optimization in an automated manner.

Abstract: Methods and apparatus of performing polarization control for optical transmissions are provided. The methods and apparatus enable polarization control devices to achieve a desired output state of polarization regardless of the input state of polarization. The desires state of polarization can be achieved by rotating waveplates in a polarization controller in a sequential fashion. Each waveplate may be continually adjusted or dithered so long as the feedback signal satisfies a feedback condition. Once the feedback signal exceeds the feedback condition, the next waveplate in the polarization controller is adjusted. This enables the methods and apparatus to rapidly adjust the state of polarization away from dead spots and minimize loss control problems.

Abstract: A system and method for controlling noise in a Raman amplifier including a plurality of pumps. A control system provides one or more control signals in response to an amplifier input or output signal. Pump parameters are adjusted in response to the control signals to achieve a desired noise figure characteristic.

Abstract: An optical fiber is colored to provide a striped pattern while maintaining a substantially uniform diameter of the fiber. In one embodiment, a coating of a first curable material having a base color is applied to an optical fiber core section using a coloring die. One or more stripes of a second curable material are applied using the die to the coating before the coating is fully cured. The stripe has a stripe color different from the base color and is formed in the coating such that the diameter of the fiber remains substantially uniform. In another embodiment, a tandem coloring system is used in which the coating is partially cured and one or more striping nozzles apply stripe(s) to the partially cured coating. In a further embodiment, the base color coating is applied and cured leaving one or more gaps. One or more stripes are applied in the gap(s) and cured to fully cover the fiber with a substantially uniform diameter.

Abstract: A method and apparatus for amplifying optical transmission signals is described. A bi-directional amplifier utilizes a pump feed-through signal from one of the optical pumps used to pump a first amplifying fiber to provide pump power to a second amplifying fiber. If an optical pump within the amplifier fails, this feed-through signal is used to pump the amplifying fiber directly pumped by the failed pump source.

Abstract: An optical fiber connector mounting assembly mounts an optical fiber connector such that the connector is located outside of a faceplate to facilitate access to an end face of the connector. The mounting assembly secures and protects the optical fiber connector. In one embodiment, the optical fiber connector includes a strain relief boot that allows the connector to be moved within a limited bend radius.

Abstract: An apparatus comprises an optical sublink including an operationally coupled optical fiber segments. The optical fiber segments are from a first optical fiber type, a second optical fiber type and a third optical fiber type. The first optical fiber type has a positive dispersion and a positive dispersion slope. The second optical fiber type has a negative dispersion and a negative dispersion slope. The third optical fiber type has one from the group of (1) a positive dispersion and a negative dispersion slope, and (2) a negative dispersion and a positive dispersion slope.