Abstract: We disclose embodiments of a WDM transmitter having an in-band OTDR capability for at least a subset of the WDM channels thereof. In an example embodiment, an OTDR-enabled WDM channel of the WDM transmitter is implemented using an optical transceiver that comprises an optical transmitter and a coherent optical receiver. The optical transmitter is configured to generate a modulated optical signal by modulating a respective carrier wavelength, transmit the modulated optical signal through an optical link as a component of the corresponding WDM signal, and provide the respective carrier wavelength to the coherent optical receiver for being used therein as an optical local oscillator. The optical receiver is configured to estimate an impulse response of the optical link by coherently detecting and processing a return optical signal produced within the optical link due to distributed reflection and/or backscattering of the modulated optical signal.

Abstract: We disclose embodiments of a WDM transmitter having an in-band OTDR capability for at least a subset of the WDM channels thereof. In an example embodiment, an OTDR-enabled WDM channel of the WDM transmitter is implemented using an optical transceiver that comprises an optical transmitter and a coherent optical receiver. The optical transmitter is configured to generate a modulated optical signal by modulating a respective carrier wavelength, transmit the modulated optical signal through an optical link as a component of the corresponding WDM signal, and provide the respective carrier wavelength to the coherent optical receiver for being used therein as an optical local oscillator. The optical receiver is configured to estimate an impulse response of the optical link by coherently detecting and processing a return optical signal produced within the optical link due to distributed reflection and/or backscattering of the modulated optical signal.

Abstract: Systems and methods for calculating a relative temperature of a fiber-optic cable using bi-directional analysis traces with an optical time-domain reflectometer (“OTDR”). Analysis of bi-directional traces along a length of fiber-optic cable yields a scaled local backscatter coefficient of the fiber. Accordingly, an initial set of measurement data is collected at a first time interval and a base scaled local backscatter along a fiber is calculated. A subsequent set of measurement data is collected at a second time interval and a subsequent scaled local backscatter along the fiber is calculated. The exemplary systems and methods described herein determines a change in scaled local backscatter as a function of a difference between the base scaled local backscatter and at least the subsequent scaled local scaled local backscatter along the fiber, and then determines a relative temperature variation of the fiber as a function of the change in scaled local backscatter.

Abstract: Described herein are systems and methods for uniquely identifying, or “fingerprinting,” optical fibers based upon hi-resolution measurements of the backscattered light. One embodiment of the disclosure of this application is related to a computer readable storage medium including a set of instructions that are executable by a processor. The set of instructions being operable to retrieve a profile for an intended fiber, the profile including unique measurement data of the intended fiber, receive from an optical frequency-domain reflectometer further measurement data from a connected fiber within a network, compare the unique measurement data of the intended fiber to the further measurement data of the connected fiber, and confirm an identity of the connected fiber as being the intended fiber when the unique measurement data matches the further measurement data, and trigger an alert when the unique measurement data does not match the further measurement data.

Abstract: Described herein are systems and methods for uniquely identifying, or “fingerprinting,” optical fibers based upon measurements from an optical time-domain reflectometer (“OTDR”). One embodiment of the disclosure of this application is related to a computer readable storage medium including a set of instructions that are executable by a processor. The set of instructions being operable to retrieve a profile for an intended fiber, the profile including unique measurement data of the intended fiber, collect further measurement data from a connected fiber within a network, compare the unique measurement data of the intended fiber to the further measurement data of the connected fiber, and confirm an identity of the connected fiber as being the intended fiber when the unique measurement data matches the further measurement data, and trigger an alert when the unique measurement data does not match the further measurement data.

Abstract: Described herein are systems and methods for calculating a relative temperature of a fiber-optic cable using bi-directional analysis traces with an optical time-domain reflectometer (“OTDR”). Analysis of bi-directional traces along a length of fiber-optic cable yields a scaled local backscatter coefficient of the fiber. Accordingly, an initial set of measurement data is collected at a first time interval and a base scaled local backscatter along a fiber is calculated. A subsequent set of measurement data is collected at a second time interval and a subsequent scaled local backscatter along the fiber is calculated. The exemplary systems and methods described herein determines a change in scaled local backscatter as a function of a difference between the base scaled local backscatter and at least the subsequent scaled local scaled local backscatter along the fiber, and then determines a relative temperature variation of the fiber as a function of the change in scaled local backscatter.

Abstract: Described herein are systems and methods for enhancing sensitivity of an optical time-domain reflectometer (“OTDR”) using bi-directional analysis techniques. One embodiment of the disclosure of this application is related to a computer readable storage medium including a set of instructions that are executable by a processor. The set of instructions being operable to collect a first set of measurement data at a first resolution to provide a relative backscatter of the fiber, collect a second set of measurement data taken at a second resolution to calculate loss along the length of fiber, and combine the first set of measurement data with the second set of measurement data to calculate the loss along the fiber at the first resolution.

Abstract: Described herein are systems and methods for enhancing the resolution of an optical time-domain reflectometer (“OTDR”). One embodiment of the disclosure of this application is related to a device, comprising an optical measuring component collecting a first set of measurement data from a forward trace along an optical fiber with the optical measuring device using depolarized light, and a processing component calculating loss along the length of fiber. The optical measuring device further collects a second set of measurement data from a backward trace along the optical fiber with the optical measuring device using depolarized light.

Abstract: Described herein are systems and methods for calculating a relative temperature of a fiber-optic cable using bi-directional analysis traces with an optical time-domain reflectometer (“OTDR”). Analysis of bi-directional traces along a length of fiber-optic cable yields a scaled local backscatter coefficient of the fiber. Accordingly, an initial set of measurement data is collected at a first time interval and a base scaled local backscatter along a fiber is calculated. A subsequent set of measurement data is collected at a second time interval and a subsequent scaled local backscatter along the fiber is calculated. The exemplary systems and methods described herein determines a change in scaled local backscatter as a function of a difference between the base scaled local backscatter and at least the subsequent scaled local scaled local backscatter along the fiber, and then determines a relative temperature variation of the fiber as a function of the change in scaled local backscatter.

Abstract: Described herein are systems and methods for enhancing the resolution of an optical time-domain reflectometer (“OTDR”). One embodiment of the disclosure of this application is related to a device, comprising an optical measuring component collecting a first set of measurement data from a forward trace along an optical fiber with the optical measuring device using depolarized light, and a processing component calculating loss along the length of fiber. The optical measuring device further collects a second set of measurement data from a backward trace along the optical fiber with the optical measuring device using depolarized light.

Abstract: Described herein are systems and methods for uniquely identifying, or “fingerprinting,” optical fibers based upon measurements from an optical time-domain reflectometer (“OTDR”). One embodiment of the disclosure of this application is related to a computer readable storage medium including a set of instructions that are executable by a processor. The set of instructions being operable to retrieve a profile for an intended fiber, the profile including unique measurement data of the intended fiber, collect further measurement data from a connected fiber within a network, compare the unique measurement data of the intended fiber to the further measurement data of the connected fiber, and confirm an identity of the connected fiber as being the intended fiber when the unique measurement data matches the further measurement data, and trigger an alert when the unique measurement data does not match the further measurement data.

Abstract: Described herein are systems and methods for enhancing sensitivity of an optical time-domain reflectometer (“OTDR”) using bi-directional analysis techniques. One embodiment of the disclosure of this application is related to a computer readable storage medium including a set of instructions that are executable by a processor. The set of instructions being operable to collect a first set of measurement data at a first resolution to provide a relative backscatter of the fiber, collect a second set of measurement data taken at a second resolution to calculate loss along the length of fiber, and combine the first set of measurement data with the second set of measurement data to calculate the loss along the fiber at the first resolution.

Abstract: Described herein are systems and methods for uniquely identifying, or “fingerprinting,” optical fibers based upon hi-resolution measurements of the backscattered light, such as can be performed by an optical frequency-domain reflectometer (“OFDR”). One embodiment of the disclosure of this application is related to a computer readable storage medium including a set of instructions that are executable by a processor. The set of instructions being operable to retrieve a profile for an intended fiber, the profile including unique measurement data of the intended fiber, receive from the OFDR further measurement data from a connected fiber within a network, compare the unique measurement data of the intended fiber to the further measurement data of the connected fiber, and confirm an identity of the connected fiber as being the intended fiber when the unique measurement data matches the further measurement data, and trigger an alert when the unique measurement data does not match the further measurement data.

Abstract: A system, amplifier and method are provided for amplifying an optical signal in an optical communications system where spans between amplifiers may vary. The system includes a Raman amplifier variable gain portion and an EDFA gain portion. The amount of Raman amplifier gain is chosen to trade off accumulation of noise with accumulation of multi-path interference. This variable Raman gain is used to equalize the loss of each span so that the amount of optical power supplied at the input of the EDFA gain portion is substantially constant throughout the system.

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: An optical interface device is provided for use in an undersea optical transmission system that includes an undersea optical transmission path, a plurality of optical repeaters located along the optical transmission path, and a selected one of any of a plurality of different vendor supplied optical transmission terminals each of which has a vendor-specific interface. The optical interface device includes a signal processing unit providing signal conditioning to optical signals received from the vendor-specific interface of the selected optical transmission terminal so that the optical signals are suitable for transmission through the undersea optical transmission path. A gain monitoring arrangement is also provided for determining a change in gain provided by any one of the optical repeaters.

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 method and apparatus is provided for obtaining status information concerning an optical transmission path. The method begins by generating a COTDR probe signal having a prescribed wavelength and transmitting optical traffic signals and the COTDR probe signal over an optical transmission path having a length corresponding to those used in regional undersea market applications. The prescribed wavelength of the COTDR probe signal is separated from wavelengths at which the optical traffic signals are located by a distance at least equal to a predetermined guard band. A backscattered and/or reflected portion of the COTDR probe signal in which status information concerning the optical path is embodied is received over the optical path. The backscattered and/or reflected portion of the COTDR probe signal is detected to obtain the status information.

Abstract: In an optical communication system that includes a transmitting terminal, a receiving terminal, and an optical transmission path optically coupling the transmitting and receiving terminals and having at least one rare-earth doped optical amplifier therein, a second optical amplifier is provided The second optical amplifier includes a first portion of the optical transmission path having a first end coupled to the transmitting terminal and a second end coupled to a first of the rare-earth doped optical amplifiers. In addition, the second optical amplifier includes a pump source providing pump energy to the first portion of the optical transmission path at one or more wavelengths that is less than a signal wavelength to provide Raman gain in the first portion at the signal wavelength.

Abstract: An undersea WDM optical transmission system is provided. The system includes first and second land-based cable stations, at least one of the cable stations includes power feed equipment (PFE) supplying electrical power to the cable at a voltage of no more than about 6 kv or less. The PFE is located in at least one of the cable stations. The system also includes an undersea WDM optical transmission cable having a length corresponding to those required in the undersea regional market. The cable includes at least one optical fiber pair for supporting bidirectional communication between the first and second cable stations. At least one repeater is located along the optical transmission cable. The repeater includes at least two optical amplifiers each providing optical gain to one of the optical fibers in the optical fiber pairs. The optical gain is in a range from about 12 to 20 dB.