The present invention provides a method, which including: determining, by a first node, an adjustment requirement for a line interface rate; and according to the adjustment requirement for the line interface rate, adjusting, by the first node, a transport bandwidth of an optical channel (OCh) link, adjusting the number of optical channel transport lanes (OTLs) in an optical channel transport unit (OTUCn) link, and adjusting the number of optical channel data lanes (ODLs) in an optical channel data unit (ODUCn) link, where the OTL is in one-to-one correspondence with the ODL. In embodiments of the present invention, according to an adjustment requirement for a line interface rate, a transport bandwidth of an OCh link is adjusted, the number of OTLs in an OTUCn link is adjusted, and the number of ODLs in an ODUCn link is adjusted, so that the line interface rate can be dynamically adjusted.

An optical access network comprises an optical network unit having a first port for connecting to a first optical link, a second port for connecting to a second optical link and an optical source. The optical source is arranged to generate a first optical signal, to transmit the first optical signal via the first port, to receive an optical seed signal via the first port and to amplify the optical seed signal. The optical seed signal has a narrower bandwidth compared to the first optical signal. A modulator is arranged to modulate the amplified optical seed signal with upstream data to form an upstream optical signal and to transmit the upstream optical signal via the second port. A polarisation modifier can modify polarisation of the first optical signal.

A wavelength-selectable laser device providing spatially-selectable wavelength(s) may be used to select one or more wavelengths for lasing in a tunable transmitter or transceiver, for example, in a wavelength division multiplexed (WDM) optical system such as a WDM passive optical network (PON). The wavelength-selectable laser device uses a dispersive optical element, such as a diffraction grating, to disperse light emitted from a laser emitter and to direct different wavelengths of the light toward a reflector at different spatial positions such that the wavelengths may be selected by allowing light to be reflected from selected spatial position(s) back into the laser emitter. Thus, the reflected light with a wavelength at the selected spatial position(s) is allowed to complete the laser cavity.

Systems and methods for detecting laser transmission bursts in a CATV network.

Methods, systems, and apparatus, for an external cavity FP laser. In one aspect, an apparatus is provided that includes a FP laser diode; a Faraday rotator (FR) coupled to receive an optical output of the FP laser diode and that rotates a polarization of the optical output; an optical fiber coupled at a first end to receive the output of the FR; a WDM filter coupled to a second end of the optical fiber to receive the optical signal from the optical fiber; and a FRM coupled directly or indirectly to an output of the WDM filter, wherein an optical output of the WDM filter is partially reflected by the FRM such that the polarization of a reflected beam is rotated, and wherein the reflected optical signal then passes through the FR with its polarization being rotated by the FR before it is injected back into the FP laser diode.

An optical network unit, ONU, (100) for a passive optical network, PON, comprising: a tunable receiver (110); a tunable transmitter (120); and a controller (130, 230) comprising a processor (132) and memory (134) containing instructions (136) executable by the processor whereby the ONU is operative to: if the tunable transmitter is on, switch the tunable transmitter off and if the tunable receiver is off, switch the tunable receiver on; determine a downstream control channel wavelength; set an operating wavelength of the tunable receiver to the downstream control channel wavelength; receive a downstream control channel signal at the downstream control channel wavelength from a central office, CO, node of the PON, the downstream control channel signal carrying an indication of an allocation of channel wavelengths to ONUs; obtain allocated downstream and upstream channel wavelengths for the ONU from the indication of an allocation of channel wavelengths to ONUs; set an operating wavelength of the tunable receiver to the allocated downstream channel wavelength and set the operating wavelength of the tunable transmitter to the allocated upstream channel wavelength; and switch the tunable transmitter on.

An optical communication system of the present invention switches a communication wavelength from a current communication wavelength to a auxiliary communication wavelength when an abnormality occurs in a communication wavelength between a station-side device and any one of a plurality of subscriber devices. Further, this optical communication system switches a communication wavelength used for communication between the subscriber device and the station-side device that perform communication using the auxiliary communication wavelength from the auxiliary communication wavelength back to the current communication wavelength when communication is recovered from an abnormality in the current communication wavelength.

The present application provides a wavelength configuration method for a multi-wavelength passive optical network, which includes: scanning, by an ONU, a downstream receiving wavelength, and receiving, downstream wavelength information of each downstream wavelength channel that is broadcast by an OLT separately through each downstream wavelength channel of a multi-wavelength PON system; establishing, by the ONU, a downstream receiving wavelength mapping table, where an entry of the downstream receiving wavelength mapping table includes downstream receiving wavelength information, drive current information of a downstream optical receiver and receiving optical physical parameter information of the ONU; selecting, by the ONU, one downstream wavelength from the downstream wavelength information broadcast by the OLT, and setting, according to the drive current information of the downstream optical receiver recorded in a related entry of the downstream receiving wavelength mapping table, an operating wavelength of the downstream optical receiver to the selected downstream wavelength.

Systems and methods for optical modulation index calibration in a CATV network.

A communication system in which a master station device is connected to a plurality of slave station devices by an optical transmission line and a plurality of wavelengths are used to perform at least one of downstream communication and upstream communication. The master station device includes: a control unit that assigns a wavelength to be used in communication to the slave station device, and that generates a control signal for notifying the slave station device of the assigned wavelength; and an optical transmitter that transmits the control signal generated by the control unit to the slave station device. The slave station device includes an optical receiver and an optical transmitter that carry out communication with the master station device using the wavelength based on the control signal received from the master station device.