Abstract: A method (1200) of transmitting digital information via a nonlinear optical channel (722), comprises receiving (1202) data (702) comprising at least a portion of the digital information. A plurality of frequency domain symbols is generated (1204) from the data, and each symbol is assigned to one of a predetermined plural number of frequency sub-bands. Each sub-band may be processed separately (1206) to reduce a peak-to-average power ratio (PAPR) of a transmitted optical signal. The optical signal (12) is then generated (1208) comprising the plural number of sub-bands, and transmitted via the nonlinear optical channel (722). The plural number of frequency sub-bands is predetermined so as to reduce nonlinear optical distortion of the optical signal within the nonlinear optical channel relative to a corresponding single frequency band signal. A corresponding information-receiving method, a transmitter apparatus and a receiver apparatus are also disclosed.

Abstract: A transmitting device, a receiving device, an optical communication system, and associated methods are provided. The transmitting device transmits an optical signal containing data, and comprises: an optical tone generator for generating at least one optical tone; at least one encoder for performing advanced coding on at least one data signal respectively, each of the at least one data signal carrying a part of the data; at least one mapper for performing high order modulation on the at least one coded data signal; and an up-converter for up-converting the at least one high-order-modulated data signal into the optical signal to be outputted through the at least optical tone. Thereby, high speed (e.g., over 1-Tb/s) transmission per single channel over a long-haul distance (e.g. over 1000-km) with error-free recovery may be achieved.

Abstract: Methods and apparatus for generating and processing a signal are disclosed. The signal may comprise a plurality of mutually orthogonal subcarriers constituting a plurality of bands. The signal may be either an optical or a radio frequency signal.

Abstract: A method (1200) of transmitting digital information via a nonlinear optical channel (722), comprises receiving (1202) data (702) comprising at least a portion of the digital information. A plurality of frequency domain symbols is generated (1204) from the data, and each symbol is assigned to one of a predetermined plural number of frequency sub-bands. Each sub-band may be processed separately (1206) to reduce a peak-to-average power ratio (PAPR) of a transmitted optical signal. The optical signal (12) is then generated (1208) comprising the plural number of sub-bands, and transmitted via the nonlinear optical channel (722). The plural number of frequency sub-bands is predetermined so as to reduce nonlinear optical distortion of the optical signal within the nonlinear optical channel relative to a corresponding single frequency band signal. A corresponding information-receiving method, a transmitter apparatus and a receiver apparatus are also disclosed.

Abstract: The invention provides methods, devices and a system for recovering the corrupted subcarrier at the local oscillator (LO) frequency in coherent optical OFDM transmission. The method includes performing advanced coding on a data signal to obtain an encoded signal; performing high order modulation on the encoded signal to obtain a high-order-modulated signal; performing OFDM modulation on the high-order-modulated signal to obtain an electrical OFDM signal; and performing up-conversion on the electrical OFDM signal to obtain an optical OFDM signal to be output.

Abstract: A transmitting device, a receiving device, an optical communication system, and associated methods are provided. The transmitting device transmits an optical signal containing data, and comprises: an optical tone generator for generating at least one optical tone; at least one encoder for performing advanced coding on at least one data signal respectively, each of the at least one data signal carrying a part of the data; at least one mapper for performing high order modulation on the at least one coded data signal; and an up-converter for up-converting the at least one high-order-modulated data signal into the optical signal to be outputted through the at least optical tone. Thereby, high speed (e.g., over 1-Tb/s) transmission per single channel over a long-haul distance (e.g. over 1000-km) with error-free recovery may be achieved.

Abstract: Methods and apparatus for generating and processing a signal are disclosed. The signal may comprise a plurality of mutually orthogonal subcarriers constituting a plurality of bands. The signal may be either an optical or a radio frequency signal.

Abstract: A method comprising splitting a received optical signal into split optical signals, the split optical signals being at least initially orthogonally polarized, coherently detecting at least one of the split optical signals and generating an electrical signal indicative thereof, and processing said electrical signal, the processing being adapted for received optical signals with orthogonal frequency division multiplexing (OFDM) modulation. A transmission system, a transmitter and a receiver are also provided.

Abstract: A device and method for reducing amplified Rayleigh backscatter at a Raman pump. A pump assembly for an optical amplifier includes a set of pump radiation sources for Raman pumping an optical transmission span. Each pump radiation source is adapted to produce radiation having a pump wavelength and a pump power. The optical transmission span is adapted to provide Raman amplification of an optical data signal when pumped by the set of pump radiation sources. At least one optical isolator is selectively located between at least one selected pump radiation source and the optical transmission span to reduce amplified Rayleigh backscatter at the pump wavelength of the selected pump radiation source from feeding back into the selected at least one pump radiation source.

Abstract: A method for maintaining amplifier saturation in a wavelength division multiplexed (WDM) optical network having a plurality of sub-bands, each sub-band including at least two signal channels which carry respective data signals, and a plurality of substitute signal transmitters, each substitute signal transmitter generating a substitute signal and corresponding to a respective one of the plurality of sub-bands, includes identifying signal channels having a predetermined characteristic within each of the plurality of sub-bands. A substitute signal transmitter is turned on if the sub-band corresponding to the substitute signal transmitter includes a predetermined number of signal channels having said predetermined characteristic. The data signals and the substitute signals are combined into a WDM signal, and the WDM signal is transmitted over an optical transmission fiber.

Abstract: A wavelength division multiplexed (WDM) optical network includes a plurality of optical transmitters, each optical transmitter generating a data signal sent over a respective one of a plurality of signal channels, the plurality of signal channels being divided into a number of sub-bands where each sub-band includes at least two signal channels, and a plurality of substitute signal transmitters, the number of substitute signal transmitters being equal to the number of sub-bands, each substitute signal transmitter generating a substitute signal which provides loading in a corresponding sub-band. The WDM optical network also includes a combining circuit which combines the data signals output from the plurality of optical transmitters and the substitute signals output from the plurality of substitute signal transmitters into a WDM signal, and an optical transmission fiber which receives the WDM signal from the combining circuit.

Abstract: A method of amplifying optical signals comprising providing a plurality of input radiation signals into the inputs of a P×V coupler, each of the input radiation signals having a respective input radiation profile having a set of pump wavelengths and pump powers corresponding to the respective wavelengths, wherein at least one set is different from at least one other set; providing V output pump radiation profiles from the outputs of the P×V coupler; and amplifying an optical data signal by coupling at least one of the V output pump radiation profiles with the optical data signal, wherein at least one of the V output pump radiation profiles has a different power than at least one other of the V output pump radiation profiles.

Abstract: A system and method of providing a transmission span for a telecommunications link based on a remote Er3+-doped fiber amplification scheme is provided, where a transmission span comprises first through third segments each respectively comprising first-third optical fibers having first-third fiber lengths and first-third physical properties. The first and third segments are optically coupled to opposing ends of the second segment. At least one of the first and third physical properties is different from the second physical property, where the first segment provides low nonlinearity, the third segment provides distributed gain, and the second segment compensates for the dispersion of the first and third segments. The span also includes a fourth optical fiber that is doped with a non-zero concentration of Er3+, and is disposed at a location in the span for remote pumping to provide discrete amplification of the optical signal.

Abstract: An optical transmission system (200) includes a set of spans (220-245), an optical transmitter (205) and a monitor unit (280). Each span of the set of spans includes a link and at least one repeater (215). The optical transmitter (205) transmits optical signals over the set of spans (220-245) according to a first launch power profile. The monitor unit (280) determines power-related parameters over a subset (220-230) of the set of spans. The optical transmitter further transmits optical signals according to a second launch power profile based on the determined power-related parameters.

Abstract: A method for locating faults in an optical communication system that includes at least two optical fibers begins by supplying an optical test signal to a first optical fiber. The optical test signal propagates on the first optical fiber in a first direction. A second optical fiber receives the optical test signal via a coupling device. The optical test signal propagates on the second optical fiber in the first direction, reaches a termination point and reflects back on the second optical fiber in a second direction opposite to the first direction. The reflected signal received on the second optical fiber may then be analyzed to determine whether a fault has occurred.

Abstract: A system and method of providing a transmission span for a telecommunications link based on a remote Er3+-doped fiber amplification scheme is provided, where a transmission span comprises first through third segments each respectively comprising first-third optical fibers having first-third fiber lengths and first-third physical properties. The first and third segments are optically coupled to opposing ends of the second segment. At least one of the first and third physical properties is different from the second physical property, where the first segment provides low nonlinearity, the third segment provides distributed gain, and the second segment compensates for the dispersion of the first and third segments. The span also includes a fourth optical fiber that is doped with a non-zero concentration of Er3+, and is disposed at a location in the span for remote pumping to provide discrete amplification of the optical signal.

Abstract: An optical amplifier is described that can couple to and amplify optical signals along multiple fiber transmission paths. The optical amplifier includes a plurality of pump radiation sources, each pump radiation source adapted to produce radiation having a set of pump wavelengths and pump powers corresponding to the respective pump wavelengths, wherein at least one set is different from at least one other set. The optical amplifier also includes a plurality of pump radiation combiners, each pump radiation combiner coupling the radiation of a respective set of pump wavelengths of a respective source of the plurality of pump radiation sources and outputting the respective coupled radiation having coupled radiation profiles via a respective pump radiation combiner output. The optical amplifier also includes a coupler, such as a PxV coupler with P inputs and V outputs.

Abstract: A pump assembly for an optical amplifier includes a plurality of pump radiation sources, each pump radiation source producing radiation at a respective one of a first number of pump wavelengths. A coupler is optically coupled to each of the plurality of pump radiation sources, receives each of the first number of pump wavelengths from the plurality of pump radiation sources, and outputs each of the first number of pump wavelengths to each one of a second number of outputs. The pump assembly also includes a plurality of pump signal combiners, each pump signal combiner optically coupled to a respective one of the second number of outputs of the coupler and receiving each of the first number of pump wavelengths output from the coupler. Each pump signal combiner placing each of the first number of pump wavelengths output from the coupler in co-propagation with a respective one of a plurality of data signals propagating on a respective one of a plurality of optical fibers.

Abstract: An optical coupler system is described. The optical coupler system is for coupling radiation from a plurality of radiation sources. The optical coupler system comprises a first optical coupler having at least a first and a second input and a first and a second output. The optical coupler also comprises a second optical coupler having at least a first and a second input and a first and a second output, wherein the first and second outputs of the first optical coupler are connected to the first and second inputs, respectively, of the second optical coupler via first and second optical links, and wherein the first and second links provide different optical paths between the first and second optical couplers such that portions of radiation energy that is input to the first input of the first optical coupler are combined incoherently at the first output of said second optical coupler.

Abstract: A system and method of providing a transmission span that compensates for signal attenuation, dispersion, and nonlinearity of an optical signal communicated between two line units of a transmission link includes dividing the transmission span into a plurality of fiber segments and selecting a particular fiber for each of the segments. The fiber selection and arrangement of fibers within the span can be selected in accordance with the nonlinearity, dispersion conditions, and distributed gain conditions of the constituent fibers. In a three segment map, the first segment can provide low non linearity, the third segment can provide distributed gain, and the second segment can compensate for the dispersion of the first and third segments. The span can be used, e.g., for distributed Raman amplification. The span can alternatively include a two segment map, a four segment map, or a map with additional segments.