Optical communication system
An optical communication system has a transmitter generating a phase-modulated optical signal (Sa, Sb, . . . , Sk); a receiver for receiving the phase-modulated optical signal; an optical communication link between the transmitter section and the receiver section. The optical communication link is a dispersion-managed optical communication link having dispersion-compensating elements propagating the phase-modulated optical signal at substantially constant optical power. The receiver has a dispersive element having a prescribed dispersion, the dispersive element receiving and converting the phase-modulated optical signal into a corresponding intensity-modulated optical signal, and an optical intensity detector fed with the intensity-modulated optical signal.
1 - 15 . (canceled)
16 . An optical communication system, comprising:
a transmitter for generating a phase-modulated optical signal (Sa, Sb, . . . , Sk);
a receiver for receiving the phase-modulated optical signal;
an optical communication link between the transmitter section and the receiver section,
the optical communication link being a dispersion-managed optical communication link comprising dispersion-compensating elements propagating the phase-modulated optical signal at substantially constant optical power, and
the receiver comprising a dispersive element having a prescribed dispersion, the dispersive element receiving and converting the phase-modulated optical signal into a corresponding intensity-modulated optical signal, and an optical intensity detector fed with the intensity-modulated optical signal.
17 . The optical communication system of claim 16 , wherein the transmitter comprises an optical carrier source generating an optical carrier, and a phase modulator driven by a modulating signal for imparting to the optical carrier a phase modulation.
18 . The optical communication system of claim 17 , wherein the optical carrier source comprises a laser, and the phase modulator comprises a LiNbO 3 modulator.
19 . The optical communication system of claim 17 , wherein the modulating signal is coded in a return-to-zero format.
20 . The optical communication system of claim 16 , wherein the receiver comprises an optical power splitter, a first and a second dispersive elements with mutually opposite dispersion fed by the power splitter, a first and a second optical intensity detectors respectively fed by the first and second dispersive elements and generating a first and a second electrical signals, and a subtractor for subtracting the first electrical signal from the second electrical signal.
21 . The optical communication system of claim 16 or 20 , wherein the dispersive element comprises one among an optical fiber section and a fiber Bragg grating.
22 . The optical communication system of claim 16 , wherein the optical communication link comprises at least one optical communication link section comprising a dispersion-compensated optical fiber span and an optical amplifier.
23 . The optical communication system of claim 22 , wherein said dispersion-compensated optical fiber span comprises one among a step-index optical fiber and non-zero dispersion-shifted optical fiber.
24 . The optical communication system of claim 22 , wherein the dispersion-compensated optical fiber span comprises at least one dispersion-compensating element.
25 . The optical communication system of claim 24 , wherein the dispersion-compensating element comprises one among a dispersion-compensating optical fiber, a transmission fiber and a fiber Bragg grating.
26 . The optical communication system of claim 22 , wherein the optical amplifier comprises one among an erbium-doped fiber amplifier, a semiconductor optical amplifier, an optical parametric amplifier and a Raman optical amplifier.
27 . The optical communication system of claim 16 or 17 , wherein the transmitter comprises at least two transmitter units, each one generating a respective phase-modulated optical signal (Sa, Sb, . . . , Sk), the phase-modulated optical signals generated by different transmitter units being differentiated by wavelength, and a wavelength multiplexer receiving the phase-modulated optical signals generated by different transmitter units and generating a wavelength division multiplexed optical signal S (Sa, Sb, . . . , Sk); and
the receiver comprises a wavelength demultiplexer receiving and demultiplexing the wavelength division multiplexed optical signal.
28 . The optical communication system of claim 27 , wherein the dispersive element is placed upstream the wavelength demultiplexer in the light propagation direction.
29 . The optical communication system of claim 27 , wherein the receiver comprises at least two receiver units, each one comprising a respective dispersive element downstream the wavelength demultiplexer in the light propagation direction.
30 . A method of optically transmitting information, comprising:
generating a phase-modulated optical carrier according to the information to be transmitted;
propagating the modulated optical carrier through an optical link; and
receiving and demodulating the modulated optical carrier,
said propagating the modulated optical carrier comprising managing a dispersion of the optical link to keep almost constant the optical power of the phase-modulated optical carrier, and
said receiving and demodulating the modulated optical carrier comprising converting the phase-modulated optical carrier into a corresponding intensity-modulated optical carrier by subjecting the phase-modulated optical carrier to a prescribed dispersion, and demodulating the intensity-modulated optical carrier.