A transmission device includes a first signal processing circuit configured to average transmission quality of a first data signal based on a third data signal, a second signal processing circuit configured to average transmission quality of a second data signal based on a fourth data signal; and a processor configured to allocate a channel in a transmission path that transmits the first data signal and a channel in a transmission path that transmits the second data signal, based on a first index value indicating transmission quality of a first optical signal in the transmission path, the first optical signal being generated based on the averaged first data signal and a second index value indicating transmission quality of a second optical signal in the transmission path, the second optical signal being generated based on the averaged second data signal.

A method of controlling a wavelength of a wavelength tunable laser module includes: referring to data of measured frequencies and wavelength filter control values at two or more points for each basic frequency channel, the data being stored in a memory of a controller; selecting the basic frequency channel closest to a frequency of laser light that a laser light source is instructed to emit; calculating a first wavelength filter control value for providing the instructed frequency of laser light from the data of the measured frequencies allocated to the basic frequency channel closest to the instructed frequency and the wavelength filter control values; and controlling the transmission characteristic of a wavelength filter using the first wavelength filter control value.

Optical network systems and components are disclosed, including a transmitter comprising a digital signal processor that receives data; circuitry that generate a plurality of electrical signals based on the data; a plurality of filters, each of which receiving a corresponding one of the plurality of electrical signals, a plurality of roll-off factors being associated with a respective one of the plurality of filters; a plurality of DACs that receive outputs from the digital signal processor, the outputs being indicative of outputs from the plurality of filters; a laser that supplies light; and a modulator that receives the light and outputs from the DACs, and supplies a plurality of optical subcarriers based on the outputs, such that one of the optical subcarriers has a frequency bandwidth that is wider than remaining ones of the optical subcarriers, said one of the optical subcarriers carrying information for clock recovery.

Optical network systems and components are disclosed, including a transmitter comprising a digital signal processor that receives data; circuitry that generate a plurality of electrical signals based on the data; a plurality of filters, each of which receiving a corresponding one of the plurality of electrical signals, a plurality of roll-off factors being associated with a respective one of the plurality of filters; a plurality of DACs that receive outputs from the digital signal processor, the outputs being indicative of outputs from the plurality of filters; a laser that supplies light; and a modulator that receives the light and outputs from the DACs, and supplies a plurality of optical subcarriers based on the outputs, such that one of the optical subcarriers has a frequency bandwidth that is wider than remaining ones of the optical subcarriers, said one of the optical subcarriers carrying information for clock recovery.

In order to identify occupied bands in an optical transmitter with high accuracy, a band identifying circuit includes an optical intensity controller configured to change, by a prescribed level, an optical intensity of an optical signal outputted from a target-of-identification optical transmitter among a plurality of optical signals respectively outputted from a plurality of optical transmitters, constituting a wavelength-multiplexed optical signal, and having mutually different wavelengths, a spectrum acquisition circuit configured to measure an optical intensity of each wavelength of the wavelength-multiplexed optical signal and output a result of the measurement as a spectrum, and a band identifier configured to identify a band occupied by the target-of-identification optical transmitter, based on a change amount of the outputted spectrum.

A reception device 20 is configured to include a separation means 21 and a plurality of optical reception means 22. Each optical reception means 22 further includes an optical/electrical conversion means 23, a reception coefficient computation means 24, and a band restoration means 25. The separation means 21 separates a multiplexed signal into which signals of respective channels to which spectral shaping that narrows bandwidth to less than or equal to a baud rate is applied as band narrowing filter processing on the transmission side, based on characteristics of a transmission line are multiplexed at spacings less than or equal to the baud rate. Each band restoration means 25 applies processing having inverse characteristics to those of the band narrowing filter processing to a reception signal, based on the band narrowing parameter acquired by the reception coefficient computation means 24 and thereby restores the band of the reception signal.

An optical communication apparatus receives a signal in which optical signals each including multiplexed subcarriers are frequency multiplexed, and includes: transceivers to perform reception process on a processing target band in which any one of the optical signals is included and to calculate a frequency offset amount between local light and a reception target optical signal that is included in the processing target band and calculate a carrier frequency interval between the local light and an optical signal adjacent to the reception target optical signal; and a frequency control unit to calculate an adjustment amount when an optical communication apparatus that is a source of the optical signals adjusts the frequencies of the optical signals based on the frequency offset amount and the carrier frequency interval calculated by the transceivers and to transmit the calculated adjustment amount to the optical communication apparatus that is a source of the optical signals.

Photonic devices, photonic integrated circuits, optical elements, and techniques of making and using the same are described. A photonic device includes an input region adapted to receive an optical signal including a multiplexed channel characterized by a distinct wavelength, a dispersive region optically coupled with the input region to receive the optical signal, the dispersive region including a plurality of sub-regions defined by an inhomogeneous arrangement of a first material and a second material, and a plurality of output regions optically coupled with the input region via the dispersive region. The plurality of sub-regions can include an input channel section, an in-coupler section, a parallel channel section, an out-coupler section, and an output channel section. The plurality of sub-regions together can configure the photonic device to demultiplex the optical signal and to isolate the multiplexed channel at a first output region of the plurality of output regions.

Provided are a next generation in-building relay system and method. The system includes: a 5G signal providing unit configured to down-convert a millimeter wave radio frequency signal to an intermediate frequency signal; a 5G master hub unit configured to convert the intermediate frequency signal into a radio over fiber (RoF) signal and transmit the RoF signal; an optical coupling unit configured to couple a digital optical signal output from a master hub unit and the analog optical signal output from the 5G master hub unit and transmit the coupled signal to an optical cable; and an optical distribution unit configured to separate the digital optical signal and the analog optical signal from the coupled signal, transmit the digital optical signal to a remote optical relay unit, and transmit the analog optical signal to distributed remote units.

A signal processing apparatus and method for monitoring channel spacing which may be configured in a receiver and includes: a first determining unit to determine a frequency range of a pilot of a center channel and a frequency range of a pilot of a neighboring channel using a receive signal; a second determining unit to determine a center channel frequency offset of the center channel pilot according to the center channel frequency range, and determine a frequency offset of the neighboring channel pilot according to the neighboring channel frequency range; and a third determining unit to determine channel spacing between the center channel and the neighboring channel according to the center channel frequency offset, the neighboring channel frequency offset and a frequency of a pilot signal at a transmitter side.