A method for establishing an embedded optical communication channel in an optical WDM transmission system including: creating, at the central network device, a broad-band optical signal, supplying the broadband optical signal, transmitting the broadband optical signal and the plurality of second optical channel signals to an optical demultiplexer device, transmitting an optical signal consisting of a dedicated second optical channel signal and a filtered broadband optical signal; receiving the optical signal and creating a corresponding electrical receive signal and extracting the electrical signal corresponding to the filtered broadband optical signal from the electrical receive signal and detecting whether the electrical signal contains information intended for the respective first channel transceiver.

Aspects of the disclosure provide for methods and systems for feedback control of mode MUX and DEMUX. An aspect of the disclosure provides for a method associated with a mode MUX. The method includes modulating each WDM signal of a first set of WDM signals with a pilot tone of different frequency. The method further includes spatially multiplexing the first set of WDM signals to generate a multi-mode signal. The method further includes detecting the pilot tones from the multi-mode signal. The method further includes tuning the mode MUX based on the detecting. Another aspect of the disclosure provides for a method associated with a mode DEMUX. The method includes spatially demultiplexing a multi-mode signal into a set of WDM signals. The method further incudes detecting pilot tones from the set of WDM signals and tuning the mode DEMUX based on the detecting.

Embodiments of the present disclosure provide an optical signal transmission method, apparatus, and device. The method at a first device side comprises: n first colored optical modules respectively transmit optical signals with the frequency being f and the wavelengths respectively being λ1-λn, wherein λ1-λn are different from each other; and in-band optical layer operation, administration, and maintenance (0AM) information with the modulation frequency being k1-kn is separately superimposed on the optical signals with the wavelengths respectively being λ1-λn.

The disclosure is directed to a method and system for generating a pilot tone for an optical signal with an optical telecommunications system. The pilot tone is generated in the digital domain by modulating the data to be transmitted to a destination node within the optical telecommunications network. The modulation of the data introduces occurrence modulation to the optical signal.

The invention relates to a method for creating a control channel in an optical transmission signal, wherein the optical transmission signal (S.sub.DS,i, S.sub.US,i) includes an optical carrier frequency component, a higher frequency modulation component carrying user information to be transported from a first end to a second end of an optical transmission link and a lower frequency modulation component carrying control information, the higher frequency modulation component realizing a user channel and the lower frequency modulation component realizing the control channel, and wherein the lower frequency modulation component is created by amplitude modulation. According to the invention, the lower frequency modulation component includes a binary digital pilot tone signal component which corresponds to a pilot tone signal having a predetermined pilot tone frequency (f.sub.i).

The invention relates to a method for establishing a communication channel, preferably an embedded control channel, between a central network node and at least one network unit to be integrated in a communication network including the central network node and an arbitrary but limited number of network units. The central network node is adapted to create and output a wavelength-division multiplex (WDM) downstream signal including downstream channel signals to be transmitted to the network units and to receive a WDM upstream signal including upstream channel signals created by the network units.

Provided is an optical transceiver including: a receiver configured to receive an optical transmission signal including wavelength information from another optical transceiver through a multiplexer/demultiplexer connected to the receiver; and a controller configured to identify a reception wavelength for communication with the other optical transceiver and to determine a wavelength corresponding to the reception wavelength as a transmission wavelength for communication with the other optical transceiver, based on the wavelength information included in the optical transmission signal.

Since safe utilization of an optical transmission system is impaired if a system is adopted in which a wavelength band is divided into sub-bands and a different user is allocated to each sub-band, the optical signal monitoring device of the present invention includes: an optical signal information generating means for monitoring wavelength multiplexed signal light comprising sub-band optical signals belonging to each of a plurality of sub-bands classified by means of identification information, and generating wavelength multiplexed signal information including optical power information of each wavelength in the wavelength multiplexed signal light; a sub-band signal information generating means for generating sub-band signal information associated with the identification information, for each of the plurality of sub-bands, on the basis of the wavelength multiplexed signal information; and a sub-band signal information control means for controlling the utilization of the sub-band signal information, on the basis of the identification information.

Provided is an optical transceiver including: an optical transmitter configured to sequentially generate a plurality of optical transmission signals each including transmission wavelength information and output the plurality of optical transmission signals to a connected multiplexer/demultiplexer; and a controller configured to generate the transmission wavelength information for each of the plurality of optical transmission signals.

Provided is an optical transceiver including: a receiver configured to receive an optical transmission signal including wavelength information from another optical transceiver through a multiplexer/demultiplexer connected to the receiver; and a controller configured to identify a reception wavelength for communication with the other optical transceiver and to determine a wavelength corresponding to the reception wavelength as a transmission wavelength for communication with the other optical transceiver, based on the wavelength information included in the optical transmission signal.