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).

A network or system in which a hub or primary node may communicate with a plurality of leaf or secondary nodes. The hub node may operate or have a capacity greater than that of the leaf nodes. Accordingly, relatively inexpensive leaf nodes may be deployed to receive data carrying optical signals from, and supply data carrying optical signals to, the hub node. One or more connections may couple each leaf node to the hub node, whereby each connection may include one or more spans or segments of optical fibers, optical amplifiers, optical splitters/combiners, and optical add/drop multiplexer, for example. Optical subcarriers may be transmitted over such connections, each carrying a data stream. The subcarriers may be generated by a combination of a laser and a modulator, such that multiple lasers and modulators are not required, and costs may be reduced. As the bandwidth or capacity requirements of the leaf nodes change, the number of subcarriers, and thus the amount of data provided to each node, may be changed accordingly. Each subcarrier within a dedicated group of subcarriers may carry OAM or control channel information to a corresponding leaf node, and such information may be used by the leaf node to configure the leaf node to have a desired bandwidth or capacity.

A system comprising a hub transceiver coupled to a first network node; and a plurality of edge transceivers, each configured to be communicatively coupled to a respective second network node, and to the hub transceiver, wherein the hub transceiver is operable to transmit a first message to each of the edge transceivers, the first message comprising an indication of available optical subcarriers and availability to use multiple non-contiguous optical subcarriers; receive, a service request identifying a selected subset of the available optical subcarriers including a non-contiguous first optical subcarrier and second optical subcarrier, transmit a second message to indicate either a success or a failure, and receive, via the selected subset, data from the second network node, and wherein at least one of the edge transceivers is operable to, transmit, using the selected subset of available optical subcarriers, data from the second network node to the first network node.

The present application provides an optical port auto-negotiation method, including: a: selecting a downstream to-be-received wavelength; b: listening to a downstream message on the selected downstream to-be-received wavelength, performing c if a wavelength idle message is received, and returning to a if no wavelength idle message is received within a specified or fixed time, where the wavelength idle message is used to identify that the wavelength is not occupied or not allocated; c: sending a wavelength application message on an upstream wavelength, performing d if a wavelength grant message is received in a downstream direction; otherwise, going back to a or b, where the wavelength application message is used to identify a request for allocation of the wavelength, and the wavelength grant message is used to identify acknowledgment of wavelength allocation; and d: setting an optical port auto-negotiation success flag bit. The present application further provides an optical module.

Systems and methods for providing onsite support to technicians of a network include a hardware means for automatically detecting the presence of an onsite technician at the network node, and providing support to the onsite technician through a communications channel provided by the network node. The communications channel can be an optical service channel or a general communication channel (GCC) configured according to G.709 standard, for example. The hardware means can be further configured to determine an identity of the onsite technician and/or authenticate the onsite technician. The hardware means may comprise a dongle communicatively coupled to a network element or shelf at the network node via a universal serial bus (USB) port or BLUETOOTH connection.

To use a plurality of wavelength bands, this seabed branching device comprises: a first demultiplexing unit that demultiplexes a wavelength multiplexed optical signal, which was input from a first terminal, into a first wavelength multiplexed optical signal and a second wavelength multiplexed optical signal; an optical add/drop unit that outputs at least a third wavelength multiplexed optical signal included in the first wavelength multiplexed optical signal to a second terminal station, and outputs at least a fifth wavelength multiplexed optical signal by multiplexing a fourth wavelength multiplexed optical signal included in the first wavelength multiplexed optical signal and a wavelength multiplexed optical signal input from the second terminal station; and a first multiplexing unit that multiplexes the second wavelength multiplexed optical signal and the fifth wavelength multiplexed optical signal, which was input from the optical add/drop unit, and outputs the result to a third terminal station.

An optical transmission apparatus includes: a plurality of optical transmitters configured to transmit optical signals having variable wavelengths, respectively; a multiplexer configured to wavelength-multiplex the optical signals transmitted from the plurality of optical transmitters in a transmission band of an optical device through which the optical signals is transmitted; and a controller configured to control, in response to nonexistence of an optical signal having a second wavelength adjacent to a first wavelength closest to an outer edge of the transmission band in the optical signals, an optical transmitter corresponding to the first wavelength so as to shift the first wavelength in a direction toward the second wavelength.

A method of power control of an optical signal transmitted by a first network element. The first network element comprising a laser and a bandpass filter operating on the optical signal produced by said laser, whereas the method comprises receiving (106) information indicative of a power level of the optical signal transmitted by the first network element; and tuning (110) the laser output wavelength in response to said received information.

Techniques are described for implementing an out-of-band communication channel used to exchange control channel information in sub-carrier-based optical communication systems. In an example implementation, a transmitter includes a laser operable to supply an optical signal, a digital signal processor operable to supply first electrical signals based on first data input to the digital signal processor and second data input to the digital signal processor, digital-to-analog conversion circuitry operable to output second electrical signals based on the first electrical signals, modulator driver circuitry is operable to output third electrical signals based on the second electrical signals, and an optical modulator operable to supply first and second modulated optical signals based on the third electrical signals. The first modulated optical signal includes a plurality of optical subcarriers carrying user data. The plurality of optical subcarriers also being amplitude modulated to carry control information.

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.