Methods and apparatuses for restoring lost signal in a network transmission line are disclosed. A first optical signal transmitted from a first optical module is received at an optical switch, the first optical signal having a first optical spectrum with data encoded into the first optical signal. A second optical signal having a second optical spectrum corresponding to the first optical spectrum without data encoded into the second optical signal, is received at the optical switch, the second optical signal the second optical signal transmitted from an amplified spontaneous emission source. Detecting, at a first photo detector, a loss of optical spectrum in the first optical signal, and, in response to detecting the loss of optical spectrum in the first optical signal, switching the optical switch from passing the first optical signal to passing the second optical signal thereby supplying at least one idler carrier without data imposed.

An optical transmission device in an optical network in which a first optical path and a second optical path are set, the optical transmission device locating on the second optical path, the optical transmission device includes; a storage unit configured to store control data for a control of an optical transmission power to the second optical path, the control being performed based on a training signal received through the second optical path; and a controller configured to control the optical transmission power to the second optical path, based on the control data stored in the storage unit, according to a detection of an optical path change by which an optical path transmitting a main signal is changed from the first optical path to the second optical path.

In order to prevent a signal which a terminal station does not require from being intercepted by the terminal station without greatly changing the power of optical signals to be transmitted from a node to the terminal station, a node device is provided with: a first optical unit which outputs a first optical signal received from a first terminal station and addressed to a second terminal station, and a second optical signal received from the first terminal station, addressed to a third terminal station, and having a different wavelength band from the first optical signal; and a second optical unit to which the first and second optical signals outputted from the first optical unit are inputted, and which shifts the frequency of the first optical signal by a predetermined amount to create a fourth optical signal, passes the second optical signal without any change, couples the second and fourth optical signals, and transmits a resultant signal to the third terminal station.

The invention discloses a communication method includes: receiving, by the ONU by using the first port or the second port, a wavelength switching request message delivered by the OLT, where the wavelength switching request message carries second wavelength channel information and port information that is of the second port; switching, by the ONU, an operating wavelength channel of an optical module connected to the second port from a first wavelength channel to a second wavelength channel corresponding to the second wavelength channel information; and sending, by the ONU, a wavelength switching complete message to the OLT by using the first port. According to the communication method provided in embodiments of the present invention, quick wavelength switching is performed based on the second port, so that a service is not interrupted in a wavelength switching process, and user experience is better.

An optical network including an input to receive from an optical network light comprising plural wavelength components. An optical wavelength selective filter, optically connected to the input, extracts a first wavelength component of the plural wavelength components from the light, thereby providing a first optical signal including the first wavelength component and a second optical signal including a remainder of the plural wavelength components a light emitter to provide a modulated broadband optical signal. A first output, optically connected to the optical wavelength selective filter, receives a first portion of the second optical signal for transmission to a light detector and a second output, optically connected to optical wavelength selective filter, receives a second portion of the second optical signal for transmission to the optical network.

An avionics unit for an avionics network is disclosed having a light emitter to provide a modulated broadband optical signal. The avionics unit also includes a first optical interface and a second optical interface. The first optical interface is optically connected to the light emitter and is to receive a removable wavelength selective filter to extract a modulated narrowband optical signal from the modulated broadband optical signal. The second optical interface is optically connected to the first optical interface and is to output the modulated narrowband optical signal.

Example embodiments of the present invention relate to optical wavelength directing devices used to construct compact optical nodes.

There is provided an optical transmission control device includes a memory, and a processor coupled to the memory and the processor configured to aggregate information of candidacy sections having a possibility that communication is discontinued among wavelength-multiplexed transmission sections, classify, based on the aggregated information, optical paths set between optical transmission devices into a first optical path on which, when communication in the candidacy sections is discontinued, an optical signal is not transmitted, and a second optical path on which, when the communication in the candidacy sections is discontinued, an optical signal is transmitted, and determine a wavelength allocation in a first wavelength group of the first optical path and a second wavelength group of the second optical path so that a difference in gain wavelength characteristics of the first optical path and the second optical path is equal to or less than a predetermined level.

As network traffic grows and more data needs to be transmitted through a network, it is desired to use optical switching systems that allow for switching between a large number of nodes. An optical switching system according to one embodiment disclosed herein allows different nodes to transmit optical signals having the same optical wavelength, in order to accommodate a larger number of nodes. For example, one cluster of nodes may transmit data using optical wavelengths that are the same as optical wavelengths that may also be used by other clusters of nodes. A controller performs scheduling and reconfiguration in the optical switching system, as needed, e.g. in order to mitigate collisions.

The invention relates to an optoelectronic transceiver device comprising a first optical connector (OC1) capable of connection to a first bidirectional optical fibre (OF1), and a second optical connector (OC2) capable of connection to a second bidirectional optical fibre (OF2), the device further comprising: an insertion-extraction module (ADM) capable of: extracting a wave-length (λ.sub.Rx) from a plurality of wavelengths constituting a first optical signal received by the first optical connector (OC1) and transmitting the first optical signal without the extracted wavelength to the second optical connector (OC2); inserting a wavelength (λ.sub.Tx) into a second optical signal received by the second optical connector (OC2) and transmitting the second optical signal with the inserted wavelength to the first optical connector (OC1); an electric-optical conversion module (EC1) capable of providing the insertion-extraction module with the wavelength (λ.sub.Tx) inserted into the second optical signal from an incoming electric signal (Data Tx); and an optical-electric conversion module (EC2) capable of converting the wavelength (λ.sub.Rx) extracted from the first optical signal by the insertion-extraction module into an outgoing electric signal (Data Rx).