Abstract: An optical communication system includes a gain medium that is capable of receiving at least one optical signal that includes one or more optical signal wavelengths. The system also includes one or more pump sources that are capable of generating at least one pump signal for introduction to the gain medium. The pump signal includes one or more fractional Raman order pump wavelengths having a Raman gain peak that is a non-integer multiple of one stokes shift from each of the one or more optical signal wavelengths. In one particular embodiment, the pump signal interacts with the optical signal as the pump signal traverses at least a portion of the gain medium.

Abstract: An optical amplification mechanism that introduces optical pump(s) into one port of an optical circulator. The optical circulator directs the optical pumps from that port into another port that is coupled to the output of a gain stage. The optical pump(s) then pass from the output to the input of the gain stage while amplifying an optical signal passing from the input to the output of the gain stage. A residual amount of optical pump(s) that exits the input of the gain stage is reflected back into the input of the gain stage. The reflected optical pump(s) then further assists in the amplification of the optical signal. Other embodiments are also disclosed.

Abstract: The alteration of the bandwidth of an optical amplifier. Before alteration, optical signals having a first set of wavelengths are provided through a gain medium of the optical amplifier. In addition, a first pump having a set of pump wavelengths is propagated through the gain medium to thereby amplify the optical signals. After alteration, optical signals having at least a partially different set of wavelengths are able to be optically amplified by coupling a second pump into the optical medium. The second pump is at least partially distinct from the first pump in that the second pump includes at least one pump wavelength that was not included in the first pump.

Abstract: Optical amplification by combining two or more optical signals from separate optical fibers, amplifying the combined signal using an optical fiber, and separating the amplified signals into their constituent optical signals. The separated optical signals may then be sent further in the direction they had been heading before combination. This allows multiple optical signals to be amplified using a single optical amplifier, perhaps even in a single optical fiber. Although not required, the two optical signals may even be travelling in different directions.

Abstract: A method of communicating an optical signal includes generating an optical signal at a bit rate of at least 2.5 Gb/s. The optical signal including at least thirty optical channels. In one particular embodiment, at least some of the thirty optical channels reside within a 1567-1620 nanometer wavelength range. The method also includes receiving the optical signal at a ROPA that includes a rare-earth doped optical fiber. In addition, the method includes introducing a pump signal to a communication span of the unrepeatered optical communication system. The pump signal operable to amplify the optical signal by Raman amplification within the communication span and including at least one pump signal wavelength operable to excite the rare-earth doped fiber. The method further includes receiving the optical signal after the optical signal has traversed at least 200 kilometers of the communication span.

Abstract: A method of communicating an optical signal includes generating an optical signal at a bit rate of at least 2.5 Gb/s. The optical signal including at least thirty optical channels. In one particular embodiment, at least some of the thirty optical channels reside within a 1567-1620 nanometer wavelength range. The method also includes receiving the optical signal at a ROPA that includes a rare-earth doped optical fiber. In addition, the method includes introducing a pump signal to a communication span of the unrepeatered optical communication system. The pump signal operable to amplify the optical signal by Raman amplification within the communication span and including at least one pump signal wavelength operable to excite the rare-earth doped fiber. The method further includes receiving the optical signal after the optical signal has traversed at least 200 kilometers of the communication span.

Abstract: An optical communication system is operable to communicate a plurality of wavelength signals at a bit rate of at least 9.5 gigabits per second over a multiple span communication link spanning at least 400 kilometers without optical regenerators. The plurality of wavelength signals include a bandwidth of more than 32 nanometers separated into at least 160 optical channels. The system includes a plurality of optical transmitters implementing a forward error correction (FEC) coding technique. The FEC encoded wavelength signals comprise a bit error rate of 10?09 or better after FEC decoding. The system also includes at least five (5) optical add/drop multiplexers (OADMs), each coupled to one or more spans of the multiple span communication link. The system further includes a plurality of amplifiers each coupled to one or more spans of the communication link, at least a majority of the amplifiers comprise a distributed Raman amplification stage.

Abstract: An optical communication system includes a first end terminal comprising a first transponder operable to receive a first electrical signal and generate an optical signal based at least in part on the first electrical signal for communication to a multiple span communication link. The optical signal experiences at least partial dispersion compensation from an optical dispersion compensating element as it traverses the communication link. The system also includes a second end terminal comprising a second transponder operable to receive the optical signal and generate a second electrical signal based at least in part on the optical signal. At least one of the first and second end terminals further includes an electronic dispersion compensation module operable to provide electronic dispersion compensation to at least a portion of at least one of the first and second electrical signals.

Abstract: An optical communication system includes a plurality of optical add/drop multiplexers (OADMs). The plurality of OADMs includes at least five low distortion OADMs. Each OADM is coupled between spans of a multiple span communication link and operable to receive a multiple wavelength signal. The multiple wavelength signal includes a plurality of bands of wavelength signals each separated from other bands of wavelength signals by one or more guard-channels. In one embodiment, each of the at least five low distortion OADMs adds/drops a common first band of wavelengths to/from the multiple wavelength signal. In some embodiments, a spectral distortion associated with a pass-through wavelength signal spectrally adjacent to one of the one or more guard-channels is no more than three decibels after exiting the last of the plurality of low distortion OADMs. In those embodiments, the guard-channel is adjacent to the first band of wavelengths.

Abstract: In one of several embodiments, a method of communicating optical signals comprises communicating a plurality of optical signals over an optical communications medium, wherein each of at least some of the plurality of optical signals comprises a launch power that is a function of a noise property measured at or near a center wavelength of that signal. Launch powers of the plurality of optical signals primarily decrease with increasing center wavelengths of the plurality of optical signals.

Abstract: An optical communication system is operable to communicate a plurality of wavelength signals at a bit rate of at least 9.5 gigabits per second over a multiple span communication link spanning at least 400 kilometers without optical regenerators. The plurality of wavelength signals include a bandwidth of more than 32 nanometers separated into at least 160 optical channels. The system includes a plurality of optical transmitters implementing a forward error correction (FEC) coding technique. The FEC encoded wavelength signals comprise a bit error rate of 10?09 or better after FEC decoding. The system also includes at least five (5) optical add/drop multiplexers (OADMs), each coupled to one or more spans of the multiple span communication link. The system further includes a plurality of amplifiers each coupled to one or more spans of the communication link, at least a majority of the amplifiers comprise a distributed Raman amplification stage.

Abstract: An optical communication system includes a plurality of optical add/drop multiplexers (OADMs). The plurality of OADMs includes at least five low distortion OADMs. Each OADM is coupled between spans of a multiple span communication link and operable to receive a multiple wavelength signal. The multiple wavelength signal includes a plurality of bands of wavelength signals each separated from other bands of wavelength signals by one or more guard-channels. In one embodiment, each of the at least five low distortion OADMs adds/drops a common first band of wavelengths to/from the multiple wavelength signal. In some embodiments, a spectral distortion associated with a pass-through wavelength signal spectrally adjacent to one of the one or more guard-channels is no more than three decibels after exiting the last of the plurality of low distortion OADMs. In those embodiments, the guard-channel is adjacent to the first band of wavelengths.

Abstract: An optical communication system includes a first end terminal comprising a first transponder operable to receive a first electrical signal and generate an optical signal based at least in part on the first electrical signal for communication to a multiple span communication link. The optical signal experiences at least partial dispersion compensation from an optical dispersion compensating element as it traverses the communication link. The system also includes a second end terminal comprising a second transponder operable to receive the optical signal and generate a second electrical signal based at least in part on the optical signal. At least one of the first and second end terminals further includes an electronic dispersion compensation module operable to provide electronic dispersion compensation to at least a portion of at least one of the first and second electrical signals.

Abstract: An apparatus and method are described for combining optical amplification and dispersion compensation in a Raman amplifier. A Dispersion-Managing Raman Amplifier (DMRA) combines Raman amplification with dispersion compensation by selecting the length and dispersion of the gain fiber to balance the dispersion of the link. This gain fiber is also single-mode at the signal and pump wavelengths. The pumping level is adjusted to balance the losses from the gain fiber and transmission link, while the pumping configuration is selected to remain within the 3 dB loss length for the pumping light. When the amplifier is split into two segments, the two segments may be joined by an isolator, a gain equalization element, and/or an optical add/drop multiplexer. For WDM transmission systems based on dispersion-shifted fiber (DSF), operation in the “violet band” between 1430–1530 nm is based on Raman amplification. By using a DMRA, a dispersion and nonlinearity managed system can be implemented.

Abstract: A multi-stage optical amplifier that has an optical fiber with a first length of amplifier fiber and a second length of amplifier fiber. The optical fiber is configured to be coupled to a signal source that produces at least a signal wavelength ?s and a pump source that produces a pump wavelength ?p. Pump wavelength ?p is less than signal wavelength ?s. Signal input, signal output and pump input ports are each coupled to the optical fiber. A first lossy member is coupled to the optical fiber and positioned between the first and second lengths of amplifier fiber. A pump shunt is coupled to the signal input port and the signal output port.

Abstract: A Raman amplifier includes a Raman gain fiber comprising a length of high-dispersion gain fiber and operable to receive at least one optical signal. The Raman amplifier also includes at least one pump source capable of generating at least one pump signal that co-propagates within the Raman gain fiber with at least a portion of the at least one optical signal received by the Raman gain fiber. The length of the high-dispersion gain fiber is at least ten (10) times a walk off length between the at least one pump signal and at least one wavelength of the at least one optical signal received by the Raman gain fiber. In addition, the length of high-dispersion gain fiber is at least two (2) times a walk off length between at least two optical signal wavelengths of the at least one optical signal received by the Raman gain fiber.

Abstract: A laser diode pump includes a plurality of laser diodes each capable of generating a lasing wavelength. The laser diode pump further includes at least one wavelength combiner operable to combine the plurality of lasing wavelengths generated by the plurality of laser diodes into a multiple wavelength pump signal. In one particular embodiment, at least two of the plurality of lasing wavelengths generated by the plurality of laser diodes comprise a wavelength between 1270 nm and 1350 nm.

Abstract: A broadband fiber transmission system includes a transmission line with at least one zero dispersion wavelength ?o and transmits an optical signal of ?. The transmission line includes a distributed Raman amplifier that amplifies the optical signal through Raman gain. One or more pump sources are included and operated at wavelengths ?p for generating a pump light to pump the Raman amplifier. ? is close to ?0 and ?0 is less than 1540 nm or greater than 1560 nm.

Abstract: A nonlinear polarization amplifier stage includes a gain medium operable to receive a multiple wavelength optical signal. The amplifier further includes a pump assembly operable to generate a plurality of pump wavelengths forming a pump spectrum comprising a plurality of peaks. The amplifier also includes a coupler operable to introduce the at least one of the plurality of pump wavelengths to the gain medium to facilitate amplification of at least a portion of the multiple wavelength optical signal through nonlinear polarization. In one particular example, at least a wavelength or an intensity of the at least one of the plurality of pump wavelengths is manipulated to affect the shape of a gain curve associated with the multiple wavelength optical signal in the amplifier stage.

Abstract: A multi-stage optical amplifier includes at least a distributed Raman amplifier fiber and a discrete amplifier fiber. The amplifier is configured to be coupled to at least one signal source that produces a plurality of signal wavelengths ?s; and at least a first pump source that produces one or more pump beam wavelengths ?p. A signal input port is coupled to the amplifier. A signal output port is coupled to the amplifier. The distributed Raman and discrete amplifier fibers are positioned between the signal input port and the signal output port. A first pump input port is coupled to a first end of the distributed Raman amplifier fiber. A second pump input port is coupled to a second end of the distributed Raman amplifier fiber. The first end is located closer to the signal input port than the second end. A third pump input port is coupled to the discrete amplifier fiber.