摘要:
An optical transmitter is disclosed wherein a modulating signal, such as an NRZ signal, encoding data is combined with a time derivative of the modulating signal and coupled to a directly modulated laser in order to generate artificial transient chirp in the output of the laser effective to substantially compensate for dispersion experienced by the output of the laser traveling through a dispersive medium such as an optical fiber. In some embodiments, the time derivative is added to the modulating signal only at the falling edges of the modulating signal.
摘要:
An optical transmitter is disclosed wherein a modulating signal, such as an NRZ signal, encoding data is combined with a time derivative of the modulating signal and coupled to a directly modulated laser in order to generate artificial transient chirp in the output of the laser effective to substantially compensate for dispersion experienced by the output of the laser traveling through a dispersive medium such as an optical fiber. In some embodiments, the time derivative is added to the modulating signal only at the falling edges of the modulating signal.
摘要:
The frequency chirp modulation response of a directly modulated laser is described using a small signal model that depends on slow chirp amplitude s and slow chirp time constant τs. The small signal model can be used to derive an inverse response for designing slow chirp compensation means. Slow chirp compensation means include electrical compensation, optical compensation, or both. Slow chirp electrical compensation can be implemented with an LR filter or other RF circuit coupled to a direct modulation source (e.g., a laser driver) and the directly modulated laser. Slow chirp optical compensation can be implemented with an optical spectrum reshaper having a rounded top and relatively large slope (e.g., 1.5-3 dB/GHz). The inverse response can be designed to under-compensate, to produce a flat response, or to over-compensate.
摘要:
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. 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 phase of the laser cavity.
摘要:
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.
摘要:
An optical transmitter comprising: an optical source modulated with an input digital data signal so as to generate a first, frequency-modulated digital signal; and an amplitude modulator, modulated with the logical inverse of the input digital data signal, for receiving the first, frequency-modulated signal and generating a second, amplitude-modulated and frequency-modulated digital signal; wherein the optical source and the amplitude modulator are each configured so as to produce positive transient chirp. A method for transmitting a signal, the method comprising: generating a first, frequency-modulated digital signal by modulating an optical source with an input digital data signal; and providing a second, amplitude-modulated and frequency-modulated digital signal by passing the first, frequency-modulated digital signal through an amplitude modulator while modulating the amplitude modulator with the logical inverse of the input digital data signal; wherein the optical source and the amplitude modulator are each configured so as to produce positive transient chirp.
摘要:
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.
摘要:
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.
摘要:
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.
摘要:
A fiber 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.