Abstract: A directly modulated optical transmitter for use with a fiber optical communications system operating in the 1550 nm wavelength band exhibits very low chirp. The chirp inherently present in a directly modulated laser is cancelled by a phase modulator which optically modulates the directly modulated laser light beam by applying a 180° phase delay to a split-off portion of the input radio frequency signal. This provides a low cost transmitter capable of operating in the 1550 nm band and with laser chirp effectively cancelled or substantially reduced, thereby avoiding distortions due to laser chirp interactions with the downstream optical fiber.

Abstract: A method and apparatus is provided for reducing clipping arising in an optical transmitter. The method begins by generating a frequency multiplexed sub-carrier signal onto which information is modulated at a plurality of different sub-carrier frequencies. The method continues by decorrelating in phase at least some pulses that are formed when two or more of the different sub-carrier frequencies are in phase with one another. An optical output produced by a laser is modulated in accordance with the frequency multiplexed sub-carrier signal after at least some of the pulses have been decorrelated in phase.

Abstract: A directly modulated optical transmitter for use with a fiber optical communications system operating in the 1550 nm wavelength band exhibits very low chirp. The chirp inherently present in a directly modulated laser is cancelled by a phase modulator which optically modulates the directly modulated laser light beam by applying a 180° phase delay to a split-off portion of the input radio frequency signal. This provides a low cost transmitter capable of operating in the 1550 nm band and with laser chirp effectively cancelled or substantially reduced, thereby avoiding distortions due to laser chirp interactions with the downstream optical fiber.

Abstract: A dispersion compensator is provided that includes an input port 102 for receiving a WDM optical signal and a dispersion compensating element 110 coupled to the input port for substantially compensating the WDM optical signal for dispersion that has accumulated along an external transmission path. The dispersion compensator also includes an output port 104 for directing the dispersion compensated WDM optical signal to an external element and a dynamic power controller 106, 108, 112, 114, 116 for maintaining a total power of the WDM signal below a prescribed level prior to receipt of the WDM optical signal by the dispersion compensating element.

Abstract: A hub for use in a passive optical network (PON) includes a transmission fiber on which an information-bearing optical signal is received, a double-cladded, rare-earth doped fiber located along the transmission fiber for imparting gain to the information-bearing optical signal, and a combiner having an output coupled to the transmission fiber and a plurality of inputs. The output is coupled to the transmission fiber such that optical energy at pump energy wavelengths but not signal wavelengths are communicated therebetween. At least one pump source is optically coupled to one of the inputs of the combiner for providing optical pump energy to the double-cladded, rare-earth doped fiber. An optical splitter is also provided. The optical splitter has an input coupled to the transmission fiber for receiving an amplified, information-bearing optical signal and a plurality of outputs for directing portions of the amplified, information-bearing optical signal to remote nodes in the PON.

Abstract: A method and apparatus is provided for reducing clipping arising in an optical transmitter. The method begins by generating a frequency multiplexed sub-carrier signal onto which information is modulated at a plurality of different sub-carrier frequencies. The method continues by decorrelating in phase at least some pulses that are formed when two or more of the different sub-carrier frequencies are in phase with one another. An optical output produced by a laser is modulated in accordance with the frequency multiplexed sub-carrier signal after at least some of the pulses have been decorrelated in phase.

Abstract: A method and apparatus is provided for power balancing an optical signal wavelength to be added to an OADM having at least one drop port and at least one add port. The method begins by monitoring a power level of a first signal wavelength being dropped on the drop port and a power level of a second signal wavelength being added on the add port. The power level of the first signal wavelength is compared to the power level of the second signal wavelength. Based on the step of comparing, the optical attenuation is adjusted along the add port so that the power level of the second signal wavelength becomes substantially equal to the power level of the first signal wavelength.

Abstract: A method and apparatus for transferring information of an optical information-bearing signal from a first wavelength to a second wavelength. The method is implemented in an all-optical wavelength converter circuit which includes a laser diode in communication with a polarization controller. An information-bearing signal having a first wavelength is input to the circuit. A polarization controller adjusts the polarization of the information-bearing signal. The laser diode receives the polarization-adjusted information-bearing signal and generates a converted information-bearing signal by transferring the information of the polarization-adjusted information-bearing signal from the first wavelength to the second wavelength. The polarization controller receives the converted information-bearing signal from the laser diode, and polarizes the converted information-bearing signal.

Abstract: An optical amplifier (200) splits an optical signal into two signals (210, 212). A first amplifier section (202) receives the first signal (210). The first amplifier section (202) includes a first optical fiber (220), having a first input, for generating a first output power (230), and a first pump source (222) is coupled to the first input, for supplying a first energy amount to the first optical fiber (220). The optical amplifier (200) also includes a second amplifier section (204) to receive the second signal (212), which is arranged in parallel to, and under common control with, the first amplifier section (202). The second amplifier section (204) includes a second optical fiber (240), having a second input, for generating a second output power (250), and a second pump source (232) is coupled to the second input, for supplying a second energy amount to the second optical fiber (240). A total power (280) of the first output power (230) and the second output power (250) is at least about 600 mill Watts.

Abstract: An optical amplifier (200) splits an optical signal into two signals (210, 212). A first amplifier section (202) receives the first signal (210). The first amplifier section (202) includes a first optical fiber (220), having a first input, for generating a first output power (230), and a first pump source (222) is coupled to the first input, for supplying a first energy amount to the first optical fiber (220). The optical amplifier (200) also includes a second amplifier section (204) to receive the second signal (212), which is arranged in parallel to, and under common control with, the first amplifier section (202). The second amplifier section (204) includes a second optical fiber (240), having a second input, for generating a second output power (250), and a second pump source (232) is coupled to the second input, for supplying a second energy amount to the second optical fiber (240). A total power (280) of the first output power (230) and the second output power (250) is at least about 600 mill Watts.

Abstract: An optical amplifier (200) splits an optical signal into two signals (210, 212). A first amplifier section (202) receives the first signal (210). The first amplifier section (202) includes a first optical fiber (220), having a first input, for generating a first output power (230), and a first pump source (222) is coupled to the first input, for supplying a first energy amount to the first optical fiber (220). The optical amplifier (200) also includes a second amplifier section (204) to receive the second signal (212), which is arranged in parallel to, and under common control with, the first amplifier section (202). The second amplifier section (204) includes a second optical fiber (240), having a second input, for generating a second output power (250), and a second pump source (232) is coupled to the second input, for supplying a second energy amount to the second optical fiber (240). A total power (280) of the first output power (230) and the second output power (250) is at least about 600 mill Watts.

Abstract: An optical amplifier (200) splits an optical signal into two signals (210, 212). A first amplifier section (202) receives the first signal (210). The first amplifier section (202) includes a first optical fiber (220), having a first input, for generating a first output power (230), and a first pump source (222) is coupled to the first input, for supplying a first energy amount to the first optical fiber (220). The optical amplifier (200) also includes a second amplifier section (204) to receive the second signal (212), which is arranged in parallel to, and under common control with, the first amplifier section (202). The second amplifier section (204) includes a second optical fiber (240), having a second input, for generating a second output power (250), and a second pump source (232) is coupled to the second input, for supplying a second energy amount to the second optical fiber (240). A total power (280) of the first output power (230) and the second output power (250) is at least about 600 mill Watts.

Abstract: A method and apparatus for transferring information of an optical information-bearing signal from a first wavelength to a second wavelength. The method is implemented in an all-optical wavelength converter circuit which includes a laser diode in communication with a polarization controller. An information-bearing signal having a first wavelength is input to the circuit. A polarization controller adjusts the polarization of the information-bearing signal. The laser diode receives the polarization-adjusted information-bearing signal and generates a converted information-bearing signal by transferring the information of the polarization-adjusted information-bearing signal from the first wavelength to the second wavelength. The polarization controller receives the converted information-bearing signal from the laser diode, and polarizes the converted information-bearing signal.

Abstract: A dispersion compensator is provided that includes an input port 102 for receiving a WDM optical signal and a dispersion compensating element 110 coupled to the input port for substantially compensating the WDM optical signal for dispersion that has accumulated along an external transmission path. The dispersion compensator also includes an output port 104 for directing the dispersion compensated WDM optical signal to an external element and a dynamic power controller 106, 108, 112, 114, 116 for maintaining a total power of the WDM signal below a prescribed level prior to receipt of the WDM optical signal by the dispersion compensating element.

Abstract: A method and apparatus is provided for power balancing an optical signal wavelength to be added to an OADM having at least one drop port and at least one add port. The method begins by monitoring a power level of a first signal wavelength being dropped on the drop port and a power level of a second signal wavelength being added on the add port. The power level of the first signal wavelength is compared to the power level of the second signal wavelength. Based on the step of comparing, the optical attenuation is adjusted along the add port so that the power level of the second signal wavelength becomes substantially equal to the power level of the first signal wavelength.

Abstract: A hub for use in a passive optical network (PON) includes a transmission fiber on which an information-bearing optical signal is received, a double-cladded, rare-earth doped fiber located along the transmission fiber for imparting gain to the information-bearing optical signal, and a combiner having an output coupled to the transmission fiber and a plurality of inputs. The output is coupled to the transmission fiber such that optical energy at pump energy wavelengths but not signal wavelengths are communicated therebetween. At least one pump source is optically coupled to one of the inputs of the combiner for providing optical pump energy to the double-cladded, rare-earth doped fiber. An optical splitter is also provided. The optical splitter has an input coupled to the transmission fiber for receiving an amplified, information-bearing optical signal and a plurality of outputs for directing portions of the amplified, information-bearing optical signal to remote nodes in the PON.

Abstract: Optical amplifier system controls gain with wide dynamic range by essentially eliminating amplified spontaneous emission components from amplifier feedback signal. Spontaneous emissions power level may be estimated as a constant, estimated based on energy imparted to the amplifier or measured and then subtracted from output power signal.

Abstract: An optical transmission system is provided comprising a method and apparatus for cancelling noise in the output from a light source for broadening the line width of a light source so as to increase stimulated Brillouin scattering threshold in a standard single mode fiber with a dispersion null at 1310 nm and for using a linearized external modulator to modulate the amplified output of a distributed feedback laser providing an output at 1550 nanometers for use on a standard single mode fiber optic cable with a dispersion null at 1310 nm.

Abstract: An optical transmission system is provided comprising a method and apparatus for cancelling noise in the output from a light source for broadening the line width of a light source so as to increase stimulated Brillouin scattering threshold in a standard single mode fiber with a dispersion null at 1310 nm and for using a linearized external modulator to modulate the amplified output of a distributed feedback laser providing an output at 1550 nanometers for use on a standard single mode fiber optic cable with a dispersion null at 1310 nm.

Abstract: An optical transmission system is provided comprising a method and apparatus for cancelling noise in the output from a light source for broadening the line width of a light source so as to increase stimulated Brillouin scattering threshold in a standard single mode fiber with a dispersion null at 1310 nm and for using a linearized external modulator to modulate the amplified output of a distributed feedback laser providing an output at 1550 nanometers for use on a standard single mode fiber optic cable with a dispersion null at 1310 nm.