Patent ID: 8542997

Claim:
A passive optical network comprising an optical exchange linked by one or more optical fibers including a single optical fiber to at least one line termination device of the network, wherein the optical exchange comprises: means for transmitting a phase-modulated, NRZ-DPSK-formatted downlink optical data signal; means for converting a phase-modulated, NRZ-DPSK-formatted uplink optical data signal into an amplitude-modulated, duobinary modulation-formatted uplink optical data signal; and means for receiving the amplitude-modulated, duobinary modulation-formatted uplink optical data signal, wherein the line termination device comprises: coupling means for dividing the optical power of the phase-modulated, NRZ-DPSK-formatted downlink optical signal so as to obtain a first downlink optical signal and a second downlink optical signal, means for converting the first downlink optical signal into an amplitude-modulated, duobinary modulation-formatted downlink optical data signal; means for receiving the amplitude-modulated, duobinary modulation-formatted uplink optical data signal; and means for generating the phase-modulated, NRZ-DPSK-formatted uplink optical data signal from the second downlink optical signal, and transmitting the phase-modulated, NRZ-DPSK-formatted uplink optical data signal, wherein the phase-modulated, NRZ-DPSK-formatted downlink optical data signal and the phase-modulated, NRZ-DPSK-formatted uplink optical data signal are both transmitted over the single optical fiber.