A communication apparatus for a fibre-optic communication system for an aircraft that includes: an optical coupler; an input port optically coupled to the optical coupler via a first waveguide, the input port arranged to receive light; a modulator optically coupled to the optical coupler via a second waveguide, the modulator having a logic input and a fibre having a fibre Bragg grating (FBG) receiving light from the input port via the optical coupler, the modulator operable to vary a strain force applied to the fibre according to a logic signal received at the logic input to modulate a wavelength of a modulated light signal reflected by the FBG back to the optical coupler; and an output port optically coupled to the optical coupler via a third waveguide to receive the modulated light signal therefrom, the output port being operable to output the modulated light signal.

Methods and systems for optimizing the transmission of superchannels with different modulation formats may include pre-calculating different guardband (GB) values between superchannels and sets of power values for subcarriers to implement subcarrier power pre-emphasis (SPP). When a request for an optical path is received at a network management system, the spectral allocation of each superchannel, including a GB, is determined according to pre-specified rules based on co-propagation of the superchannels with different modulation formats.

Wavelength channels used in the optical network system are classified into downstream channels used to transmit optical signals from an optical line terminal (OLT) to an optical network unit (ONU) and upstream channels that are used to transmit optical signals from the ONU to the OLT. The wavelength channels are included in an O-band and may not overlap each other. One of the upstream channels are allocated to a wavelength band (for example, a zero-dispersion window) in which a four-wave mixing occurs. A wavelength spacing between the upstream channels and the downstream channels is determined based on a performance of separating the upstream channels and the downstream channels in a bidirectional optical sub assembly (BOSA) of the ONU. Also, a wavelength spacing between the downstream channels is determined based on a performance of separating the downstream channels in the BOSA.

First data and second data are transmitted by a simple configuration by including a generation unit that generates a wavelength-changed signal on the basis of the second data, and a transmission unit that transmits the wavelength-changed signal together with a first signal that indicates the first data.

A network design device includes a processor. The processor determines a second wavelength allocation based on a first wavelength allocation that indicates a wavelength allocation for a plurality of optical lines established in a wavelength division multiplexing optical network. The processor searches for a disconnection target optical line that is requested to be disconnected in order to realize a transition from the first wavelength allocation to the second wavelength allocation from among the plurality of optical lines. The processor generates procedure information that indicates a procedure of the transition from the first wavelength allocation to the second wavelength allocation based on a difference between the first wavelength allocation and the second wavelength allocation and a searched disconnection target optical line.

A routing and wavelength assignment method for use in an optical fiber system, comprising: (i) identifying a plurality of paths between a source node and a destination node, (ii) selecting one of the plurality of identified paths, (iii) defining within the spectrum band of the selected path one or more blocks of spectral resource, in which each block comprises either: one or more unused wavelength channels, or one or more wavelength channels having the same spectral width, (iv) obtaining an entropy value of the selected path defining the spectrum fragmentation across its spectrum band, based on a logarithm of the ratio of the number of wavelength channels in each of the one or more blocks, to the total number of wavelength channels across the spectrum band, (v) iterating (ii) to (v) until the entropy value of each of the plurality of identified paths has been determined, and (vi) choosing from the plurality of identified paths a path having the lowest entropy value.

The communication system has first and second optical systems and an optical feed fiber in communication with the first optical system and arranged to convey a feeder optical signal to the second optical system. The first optical system includes a multiplexer configured to multiplex/demultiplex between a first optical line terminal signal, a second optical line terminal signal, and the feeder optical signal. The feeder optical signal includes the first optical line terminal signal and the second optical line terminal signal. The first optical line terminal signal includes a first upstream free spectral range and a first downstream free spectral range. The second optical line terminal signal includes a second upstream free spectral range and a second downstream free spectral range. The second optical system is in communication with the optical feed fiber and is configured to multiplex and demultiplex between the feeder optical signal and optical network unit signals.

A method and apparatus for communications in a passive optical network (PON) system are provided. An optical line terminal (OLT) generates a PON downstream Physical Layer (PHY) frame comprising a downstream physical synchronization block (PSBd) that comprises a wavelength identification (ID) of at least one downstream wavelength of the plurality of downstream wavelengths. The OLT sends the PON PHY frame comprising the wavelength ID in the PSBd to ONU for confirming the at least one downstream wavelength.

A memory access system that includes a data sending apparatus, an optical transmission medium, and a data receiving apparatus. The data sending apparatus includes a signal generator, an optical switch, and an optical modulator. The signal generator controls the optical switch to output the optical wave of the wavelength corresponding to the target memory, and the optical wave carries an electrical signal corresponding to an access request, so that an optical signal carrying the access request is directly transmitted from the optical transmission medium to the data receiving apparatus without passing through the optical switch anymore, which avoids noise interference generated when the optical signal passes through the optical switch.

The communication system has first and second optical systems and an optical feed fiber in communication with the first optical system and arranged to convey a feeder optical signal to the second optical system. The first optical system includes a multiplexer configured to multiplex/demultiplex between a first optical line terminal signal, a second optical line terminal signal, and the feeder optical signal. The feeder optical signal includes the first optical line terminal signal and the second optical line terminal signal. The first optical line terminal signal includes a first upstream free spectral range and a first downstream free spectral range. The second optical line terminal signal includes a second upstream free spectral range and a second downstream free spectral range. The second optical system is in communication with the optical feed fiber and is configured to multiplex and demultiplex between the feeder optical signal and optical network unit signals.