This disclosure describes C and L band optical communications module link extender, and related systems and methods. An example method may include receiving, by a dense wave division multiplexer (DWDM) at a headend, one or more optical data signals over only an L band. The example method may also include combining the one or more optical data signals. The example method may also include outputting the combined one or more optical data signals to a first WDM at the headend. The example method may also include outputting, by a first WDM, the one or more optical data signals to an amplifier at the headend. The example method may also include amplifying, by the amplifier, the one or more optical data signals. The example method may also include outputting the amplified one or more optical data signals to a coexistence filter. The example method may also include outputting, by the coexistence filter, the amplified one or more optical data signals to an optical switch. The example method may also include outputting, by the optical switch, an egress optical data signal to a first fiber.

Provided is an optical transmitting and receiving system. The optical transmitting and receiving system may include: a Main Hub Unit (MHU) configured to perform wavelength division multiplexing on a plurality of downlink signals using a plurality of wavelengths and transmit the multiplexed downlink signal through a first optical cable; a first Remote Optical Unit (ROU) configured to perform demultiplexing on the multiplexed downlink signal received from the MHU and output a part of the plurality of downlink signals; and a second ROU configured to perform demultiplexing on the multiplexed downlink signal and output other part of the plurality of downlink signals.

This application discloses a bandwidth allocation method, an optical line terminal (OLT), an optical network unit (ONU), and a system, where the method includes receiving a bandwidth request from each ONU, where the ONU includes an ONU1, generating a bandwidth map (BWMap) message according to bandwidth requested by the ONU and bandwidth configured for the ONU, where the BWMap message includes a first allocation identifier (Alloc-ID1), a first time corresponding to the Alloc-ID1, a second allocation identifier (Alloc-ID2), and a second time corresponding to the Alloc-ID2, and both the Alloc-ID1 and the Alloc-ID2 are allocated to the ONU1 for use, and sending the BWMap message to each ONU. Therefore, a problem that a transmission delay does not satisfy a requirement when a passive optical network (PON) system is applied to mobile backhaul is resolved, a data transmission rate and data transmission efficiency are improved, and user satisfaction is improved.

Systems and methods for efficient upstream multicast in passive optical networks. An upstream multicast source communicates an upstream multicast packet to the network. Subsequent downstream packet management achieved through use of source filters prevents a reflected copy of the original upstream multicast packets from being received by the upstream multicast source.

This application discloses a bandwidth allocation method, an optical line terminal (OLT), an optical network unit (ONU), and a system, where the method includes receiving a bandwidth request from each ONU, where the ONU includes an ONU1, generating a bandwidth map (BWMap) message according to bandwidth requested by the ONU and bandwidth configured by the ONU, where the BWMap message includes a first allocation identifier (Alloc-ID1), a first time corresponding to the Alloc-ID1, a second allocation identifier (Alloc-1D2), and a second time corresponding to the Alloc-ID2, and both the Alloc-ID1 and the Alloc-ID2 are allocated to the ONU1 for use, and sending the BWMap message to each ONU. Therefore, a problem that a transmission delay does not satisfy a requirement when a passive optical network (PON) system is applied to mobile backhaul is resolved, a data transmission rate and data transmission efficiency are improved, and user satisfaction is improved.

Systems and methods for efficient upstream multicast in passive optical networks. An upstream multicast source communicates an upstream multicast packet to the network. Subsequent downstream packet management achieved through use of source filters prevents a reflected copy of the original upstream multicast packets from being received by the upstream multicast source.

An optical communication network includes a downstream optical transceiver. The downstream optical transceiver includes at least one coherent optical transmitter configured to transmit a downstream coherent dual-band optical signal having a left-side band portion, a right-side band portion, and a central optical carrier disposed within a guard band between the left-side band portion and the right-side band portion. The network further includes an optical transport medium configured to carry the downstream coherent dual-band optical signal from the downstream optical transceiver. The network further includes at least one modem device operably coupled to the optical transport medium and configured to receive the downstream coherent dual-band optical signal from the optical transport medium. The at least one modem device includes a downstream coherent optical receiver, and a first slave laser injection locked to a frequency of the central optical carrier.

Disclosed herein is a wavelength-division multiplexing device with a unified passband. In particular, disclosed is a wavelength-division multiplexing (WDM) device with at least a common port, a channel port, and a WDM filter. The common port is configured for optical communication of a multiplexed signal to the WDM filter. A demultiplexed signal of the multiplexed signal includes a first secondary demultiplexed signal within a first wavelength range and a second secondary demultiplexed signal within a second wavelength range, which are separated from each other by a third wavelength range. The first WDM filter has a single unified passband including the first wavelength range, the second wavelength range, and the third wavelength range, such that the first WDM filter is configured to pass the first secondary demultiplexed signal and the second secondary demultiplexed signal to the first channel port.

Disclosed herein is a wavelength-division multiplexing device with a unified passband. In particular, disclosed is a wavelength-division multiplexing (WDM) device with at least a common port, a channel port, and a WDM filter. The common port is configured for optical communication of a multiplexed signal to the WDM filter. A demultiplexed signal of the multiplexed signal includes a first secondary demultiplexed signal within a first wavelength range and a second secondary demultiplexed signal within a second wavelength range, which are separated from each other by a third wavelength range. The first WDM filter has a single unified passband including the first wavelength range, the second wavelength range, and the third wavelength range, such that the first WDM filter is configured to pass the first secondary demultiplexed signal and the second secondary demultiplexed signal to the first channel port.

Disclosed is an optical line terminal (OLT), including: N tunable modules, each of the N tunable modules include M tunable transmitters, the number of tuning channels of the M tunable transmitters is greater than or equal to two and the number of the tuning channels is less than MN, wherein N and M are integers greater than or equal to two.