An optical communication method includes: outputting light of a frequency allocated to an own device; separating the output light into mutually orthogonal polarized waves, modulating an in-phase component and a quadrature component in each of the polarized waves, and outputting an optical signal acquired by polarization synthesis of modulated component waves; acquiring information on a reception state of the optical signal in an optical reception device being a transmission destination of the optical signal; and controlling, based on the information on the reception state, a frequency of the light to be output, and adjusting a frequency offset being a difference between the frequency of the light to be output and a frequency of local oscillation light for use in coherent detection of the optical signal by the optical reception device.

A system for transmitting data over an optical communication path is configured to receive data to be encoded in a bitstream for transmission using an optical communication path and encodes the received data to obtain a bitstream. The system is further configured to determine that the bitstream includes a sequence of consecutive bits, and obtain a power level at which to transmit a portion of the bitstream based on a count of the consecutive bits in the sequence. The system may be configured to selectively activate a light source at a power level according to a modulation scheme to optically transmit the portion of the bitstream at the power level.

A system for transmitting data over an optical communication path is configured to receive data to be encoded in a bitstream for transmission using an optical communication path and encodes the received data to obtain a bitstream. The system is further configured to determine that the bitstream includes a sequence of consecutive bits, and obtain a power level at which to transmit a portion of the bitstream based on a count of the consecutive bits in the sequence. The system may be configured to selectively activate a light source at a power level according to a modulation scheme to optically transmit the portion of the bitstream at the power level.

An optical reception apparatus (1) of the present invention includes: a local oscillator (11) outputting local oscillation light (22); an optical mixer (12) receiving a multiplexed optical signal (21) and the local oscillation light, and selectively outputting an optical signal (23) corresponding to the wavelength of the local oscillation light from the multiplexed optical signal; a photoelectric converter (13) converting the optical signal (23) output from the optical mixer into an electric signal (24); a variable gain amplifier (15) amplifying the electric signal (24) to generate an output signal (25) whose output amplitude is amplified to a certain level; a gain control signal generating circuit (16) generating a gain control signal (26) for controlling the gain of the variable gain amplifier (15); and a monitor signal generating unit (17) generating a monitor signal (27) corresponding to the power of the optical signal (23) using the gain control signal (26).

The disclosed systems, apparatuses and methods are directed to controlling a difference between a first center frequency of a first optical subcarrier and a second center frequency of a second optical subcarrier of an optical super-channel signal in an optical network. The method comprises modulating the first optical subcarrier at a first optical side component frequency with a first side modulation frequency and modulating the second optical subcarrier at a second optical side component frequency with a second side modulation frequency. The method further comprises detecting a radio-frequency (RF) power at a modulated beat frequency tone in the modified optical signal.

A laser tuning system includes an optical transmitter having a tunable laser that transmits optical signals at various wavelengths to an optical fiber through an optical component, which attenuates a range of wavelengths of the optical signal. An optical detector detects optical returns that have been reflected from the fiber at points beyond the optical component. A tuning control module analyzes the optical returns in order to provide a tuning value for tuning the laser to a desired wavelength. As an example, the laser may be tuned in order to maximize or otherwise increase the amount of optical power passing through the optical component.

A wavelength tunable filter, an optical receiver and a method using the wavelength tunable filter are disclosed. According to an aspect of the present invention, an optical receiver module having a wavelength tunable filter is provided. The transmission wavelength or reflective wavelength of the wavelength tunable filter is tunable The optical receiver module includes the wavelength tunable filter, a heat generation unit, and a separation unit. The wavelength tunable filter transmits light of a preset wavelength and tunes the preset wavelength. The heat generation unit is in contact with at least a portion of the wavelength tuning filter. The separation unit has a preset thermal conductivity. The separation unit is in contact with at least another portion of the wavelength tunable filter to support the wavelength tunable filter and separate physically or thermally the wavelength tunable filter from other components of the optical receiver module except for the heat generation unit. The preset wavelength is determined based on a temperature of the heat generation unit.

There is provided a reception device including a receiver configured to receive a wavelength-multiplexed optical signal so as to generate a wavelength-multiplexed signal, a filter configured to pass through the wavelength-multiplexed signal having a specific wavelength and an adjacent wavelength to the specific wavelength from the wavelength-multiplexed signal, and a processor configured to detect a specific signal having the specific wavelength from the wavelength-multiplexed signal having the passed through wavelengths by the filter, and detect a first supervisory control signal having the specific wavelength and a second supervisory control signal having the adjacent wavelength from the wavelength-multiplexed signal having the passed through wavelengths by the filter.

A system identifies rogue optical network units (ONUs) on a passive optical network that uses time and wavelength division multiplexing. An optical line terminal (OLT) is configured to recognize the occurrence of errors on the upstream transmission over the network. When those errors reach a predetermined threshold, the OLT attempts to identify potential rogue ONUs by controlling the ONUs to tune to different wavelengths. The OLT first controls the ONUs to transmit on a first wavelength. The OLT then iteratively divides the ONUs into multiple groups, each group being assigned a different wavelength for upstream transmission. The OLT them monitors upstream transmission to determine which group of ONUs is exhibiting rogue behavior. This process is repeated until a small group of ONUs is isolated as a potential rogue. The potentially rogue ONUs are individually analyzed and one or more ONUs is positively identified. The system then tunes the rogue ONUs to one or more isolated channels so as not to interfere with communication by other ONUs.

Quantum channel routing utilizing a quantum channel measurement service is disclosed. A quantum channel router that is communicatively coupled to a plurality of quantum channels receives a message from a sender that is directed to a receiver. Each quantum channel is configured to convey a quantum message from a sender to a receiver. The quantum channel router identifies a quantum channel to which the receiver listens. The quantum channel router determines a message size of the message. It is determined that transmission of the message would exceed a maximum channel capacity of the quantum channel at a current point in time, and in response, the quantum channel router does not transmit the first message onto the first quantum channel at the current point in time.