Abstract: A fiber optic communication system comprising: an optical signal source adapted to produce a frequency modulated signal; and an optical spectrum reshaper (OSR) adapted to convert the frequency modulated signal into a substantially amplitude modulated signal, wherein the optical spectrum reshaper is adapted to compensate for at least a portion of a dispersion in a transmission fiber; and further including a transmission fiber coupled to the optical source, a receiver and a decision circuit coupled to the transmission fiber.

Abstract: A fiber optic transmitter comprising: a digital driver adapted to adjust the rise time and fall time of a digital input signal; an optical source adapted to receive the digital signal and produce a frequency modulated optical signal; and an optical spectrum reshaper adapted to convert the frequency modulated optical signal to an amplitude modulated optical signal. A method for transmitting an optical signal through a fiber comprising: receiving a digital input signal; adjusting the rise time and fall time of the digital input signal so as to produce an adjusted digital input signal; passing the adjusted digital input signal to an optical source so as to produce a frequency modulated optical signal; passing the frequency modulated optical signal through an optical spectrum reshaper so as to convert the frequency modulated optical signal to an amplitude modulated optical signal; and passing the amplitude modulated signal into the fiber.

Abstract: There is provided a fiber optic system comprising: a multi-wavelength source adapted to generate frequency modulated signals having different wavelengths, ?1, ?2, . . . , ?n; and an arrayed waveguide grating adapted to convert the multiplicity of frequency modulated signals into a multiplicity of substantially amplitude modulated signals, and spatially combine the different wavelengths ?1, ?2, . . . , ?n. And there is provided a method for transmitting an optical signal through a fiber comprising: operating a multi-wavelength source so as to generate frequency modulated signals having different wavelengths, ?1, ?2, . . . , ?n; passing the frequency modulated signals through an arrayed waveguide grating so as to convert the frequency modulated signals into substantially amplitude modulated signals, and spatially combine the different wavelengths ?1, ?2, . . . , ?n; and passing the substantially amplitude modulated signals into the fiber.

Abstract: A fiber optic communication system comprising: an optical signal source adapted to receive a binary base signal having a bit period T, and generate a first signal, wherein the first signal is frequency modulated; and an optical spectrum reshaper (OSR) adapted to reshape the first signal into a second signal, wherein the second signal is amplitude modulated and frequency modulated; characterized in that: the frequency excursion of the first signal is adjusted such that the frequency excursion is substantially equal to the ratio of the bit period of the digital base signal to total dispersion of the transmission fiber, whereby to increase the tolerance of the second signal to dispersion in a transmission fiber.

Abstract: A system for generating a return-to-zero differentially-phase-shift-keyed (RZ-DPSK) optical signal comprising: a driver comprising an N-level digital multilevel transformer (DMT) configured to receive a two level digital electrical signal representing 1s and 0s and output a N-level electrical signal, wherein N>2; an FM source configured to receive the N-level electrical signal output by the driver and generate an optical frequency modulated signal; and an optical spectrum reshaper (OSR) configured to receive the optical frequency modulated signal output by the FM source and generate the desired RZ-DPSK optical signal.

Abstract: A fiber optic communication system comprising: an optical signal source adapted to receive a binary base signal having a bit period T, and generate a first signal, wherein the first signal is frequency modulated; and an optical spectrum reshaper (OSR) adapted to reshape the first signal into a second signal, wherein the second signal is amplitude modulated and frequency modulated; characterized in that: the optical signal source is a laser in which frequency modulation is generated by modulating the loss of the laser cavity. A method for transmitting a signal, comprising: receiving a binary base signal having a bit period T, and generating a first signal, wherein the first signal is frequency modulated; and reshaping the first signal into a second signal, wherein the second signal is amplitude modulated and frequency modulated; characterized in that: the first signal is frequency modulated by using a laser in which frequency modulation is generated by modulating the loss of the laser cavity.

Abstract: This invention provides a system that combines a wavelength multiplexer with an FM discriminator for chirp reduction and wavelength locker in a filter to produce a wavelength division multiplexed signal with reduced chirp. A partially frequency modulation laser signal is converted into a substantially amplitude modulation laser signal. This conversion increases the extinction ratio of the input signal and further reduces the chirp. A wavelength division multiplexing (WDM) method is used for transmitting high capacity information through fiber optics systems where digital information is carried on separate wavelengths through the same fiber. Separate transmitters normally generate their respective signals that are transmitted at different wavelengths. These signals are then combined using a wavelength multiplexer to transmit the high capacity information through the fiber optic system.

Abstract: An optical transmitter comprising: (i) an electrical switch; (ii) a laser array comprising a plurality of tunable laser elements; and (iii) an Optical Spectrum Reshaper (OSR) used to reshape the output pulses from the laser elements in the laser array; wherein the electrical switch takes an input electrical digital signal and selectively directs it to a specific laser element in the DFB laser array.

Abstract: A method for transmitting a signal and a fiber optic system comprising: a frequency modulated source; an optical transmission fiber positioned to receive the output of the frequency modulated source; an optical filter positioned to receive the output of the optical transmission fiber; and an optical receiver positioned to receive the output of the optical filter; characterized in that: an optical spectrum reshaper is positioned between the frequency modulated source and the optical transmission fiber; and wherein the optical filter is a narrow band pass filter relative to the bit rate of the transmitted signal; and further wherein the frequency excursion of the frequency modulated source is between 20% and 120% of the bit rate frequency.

Abstract: A method and system for suppression of the optical carrier of an optically modulated digital signal, the method comprising the steps of: modulating the amplitude of an optical carrier with digital input data to generate an amplitude modulated optical signal; and modulating the frequency of the optical carrier of the resulting optical signal with the same digital input data. A fiber optic system comprising: an optical source adapted to produce an adiabatically chirped amplitude modulated optical signal; an optical fiber adapted to receive the optical signal; and an optical receiver; wherein the optical power of the signal launched into the fiber exceeds the stimulated Brillouin threshold of the transmission fiber for a single frequency, continuous wave signal.

Abstract: Apparatus for the generation of ultra-low noise light comprising: a laser generating light at a central frequency and having a frequency dependent relative intensity noise spectrum; and an optical filter having a substantially conjugate symmetric transfer function; wherein the center frequency of the light generated by the laser is substantially aligned with the peak transmission frequency of the filter; and wherein the transmission function of the filter is chosen, and the frequency dependent relative intensity noise spectrum of the laser is adjusted, to reduce the resulting relative intensity noise of the light at the output of the filter over a range of frequencies by causing the relative intensity noise spectrum of the laser to occur at frequencies for which the filter has substantial loss.

Abstract: This invention provides a flat dispersion frequency discriminator (FDFD) capable of having a substantially flat dispersion with either a positive or negative dispersion along the spectrum region of the discriminator. This way, a FDFD may not cause substantial distortion of the intensity patter of its output to minimize the occurrence distortion due to overshooting or undershooting of the intensity pattern depending on the relative spectral alignment of the laser output relative to the filter transmission.

Abstract: This invention generally relates to an optical filter for a fiber optic communication system. An optical filter may be used, following a directly modulated laser source, and converts a partially frequency modulated signal into a substantially amplitude modulated signal. The optical filter may compensate for the dispersion in the fiber optic transmission medium and may also lock the wavelength of the laser source.

Abstract: This invention provides a flat dispersion frequency discriminator (FDFD) capable of having a substantially flat dispersion with either a positive or negative dispersion along the spectrum region of the discriminator. This way, a FDFD may not cause substantial distortion of the intensity patter of its output to minimize the occurrence distortion due to overshooting or undershooting of the intensity pattern depending on the relative spectral alignment of the laser output relative to the filter transmission.

Abstract: A fiber optic communication system for receiving an electronic digital data signal and transmitting the same, comprising an optical signal source adapted to receive the digital data signal and to produce a frequency modulated optical signal from a directly modulated semiconductor laser; an optical spectrum reshaper adapted to convert the frequency modulated optical signal into an amplitude modulated optical signal; and compensation apparatus for compensating for the adverse effects of the thermal chirp normally induced in the frequency modulated optical signal by modulating the semiconductor laser with the electronic digital data signal.

Abstract: A method of transmitting a base band binary data contained in respective successive time cells, the data being in the form of a signal obtained by amplitude modulation and frequency modulation of a carrier wave with a 0 bit data having a 0 bit mean amplitude and a 0 bit mean frequency and a 0 bit duration and a 1 bit data having a 1 bit mean amplitude and a 1 bit mean frequency and a 1 bit duration the improvement wherein the amplitude and frequency are modulated with the same binary base band signal whereby to decrease the spectral width of the resulting modulated signal below the spectral width of the base band signal.

Abstract: There is provided method for transmitting binary data contained in respective successive time cells, the data being in the form of an optical signal obtained by amplitude modulation and frequency modulation of an optical carrier wave, with a 0 bit data value having a 0 bit mean amplitude having a 0 bit amplitude time duration and a 0 bit frequency having a 0 bit frequency duration, and a 1 bit data value having a 1 bit mean amplitude having a 1 bit amplitude time duration and a 1 bit frequency having a 1 bit frequency duration; the improvement wherein: independently adjusting the 0 bit mean amplitude relative to the 1 bit mean amplitude; independently adjusting the 0 bit frequency relative to the 1 bit frequency; and independently adjusting time duration of the frequency profile of the 1 bit relative to the time duration of the amplitude profile of the 1 bit, whereby to extend the error-free propagation of the optical signal though a dispersive optical fiber beyond the dispersion limit.

Abstract: A fiber optic communication system comprising: an optical signal source adapted to produce a binary amplitude modulated signal; and an optical spectrum reshaper adapted to receive the amplitude modulated signal and to change the instantaneous frequency of the signal at its 0-to-1 and 1-to-0 transitions so as to change the instantaneous frequency of the signal so that it is substantially constant across the 1 pulse. A method for transmitting a signal through a fiber, comprising: generating a second signal from the signal, wherein the second signal comprises a intensity profile and an adiabatic frequency profile; generating a third signal from the second signal, wherein the third signal comprises a intensity profile and a flat-topped frequency profile.

Abstract: In one form of the present invention, there is provided a fiber optic communication system comprising: an optical signal source adapted to receive a base binary signal and produce a first signal, said first signal being frequency modulated; and an optical spectrum reshaper adapted to reshape the first signal into a second signal, said second signal being amplitude modulated and frequency modulated; characterized in that: the frequency characteristics of said first signal, and the optical characteristics of said optical spectrum reshaper, being such that the frequency characteristics of said second signal are configured so as to increase the tolerance of the second signal to dispersion in a transmission fiber.

Abstract: A Distributed Feed-Back (DFB) laser integrated with an Electroabsorption (EA) modulator whose facet at the end of EA modulator section has finite reflectively to create adiabatic chirp by optical feedback to the DFB laser.