Abstract: A method to identify the wavelength of incoming light is disclosed. The method includes steps to measure a first photocurrent by setting the avalanche photodiode (APD) in a photodiode (PD) mode and a second photocurrent by setting the APD in the APD mode, and to compare a ratio of the two photocurrents with prepared references.

Abstract: In one example, an optical channel monitor includes a tunable filter, a deinterleaver, first and second optical receivers, and a control module. The tunable filter is configured to receive an optical signal having a plurality of channels spaced at a nominal channel spacing. The deinterleaver has an input with an input channel spacing Fi, an even output, and an odd output, the input being connected to an output of the tunable filter. The nominal channel spacing is between about one and two times the input channel spacing Fi. A ?20 dB bandwidth of the tunable filter is between about two and four times the input channel spacing Fi. The first and second optical receivers are coupled to the deinterleaver even and odd outputs, respectively. The control module is coupled to the tunable filter and is configured to tune the tunable filter to a desired center frequency.

Abstract: An optical receiver includes a converter configured to convert, into an electrical signal, an optical signal including error correction information, the optical signal being received from a transmitting side; a corrector configured to correct an error on the electrical signal, based on the error correction information; a threshold controller configured to control a threshold value discriminating a power of the electrical signal, based on a result of the error correction; a table configured to form therein data of a relationship between the threshold value and a power of an optical noise occurring when the optical signal is amplified within an optical transmission path; and a deriving unit configured to obtain the power of the optical noise corresponding to the threshold value from the table.

Abstract: The optical signal to noise ratio is improved when the polarization multilevel signal light is demodulated. A optical polarization multilevel signal receiving apparatus is provided with a polarization multilevel receiver configured to generate at least one estimation symbol A1 to AN estimating a state of the symbol A by utilizing a polarization state of at least one polarization multilevel symbol received in a past before the symbol A, a past value of a decision variable, and a decision result, average the estimation symbols A1 to AN and the symbol A to calculate a reference symbol Ar, and use the calculated reference symbol Ar in place of the symbol A to calculate a decision variable corresponding to a polarization state change of the received symbol R, where R is a received symbol and A is at least one past symbol used as a reference for a change.

Abstract: A method and apparatus for measuring a propagation delay of an optical signal between first and second devices in an optical transmission network, the optical signal being transmitted from the first device to the second device via a first optical fiber and from the second device to the first device via a second optical fiber. The second device includes a loopback having a first mode enabling the optical signal to be routed between the two devices. The method includes: detecting by the second device a triggering by the first device of a propagation delay measurement; receiving a measurement signal transmitted by the first device via the first optical fiber; and configuring the loopback in a second mode in which the loopback injects a return signal into the first fiber in response to the measurement signal. The first device implements a method for determining the propagation delay.

Abstract: A power amplifier includes a first amplifier unit, a second amplifier unit, a first switching element, a second switching element and a third switching element. Each of the amplifier units includes a power supply terminal, a ground terminal, an input terminal, and an output terminal, and amplifies a signal received at the input terminal according to a voltage between the power supply terminal and the ground terminal, and outputs the signal from the output terminal. The first switching element is connected between the ground terminal of the first amplifier unit and the power supply terminal of the second amplifier unit. The second switching element is connected between the ground terminal of the first amplifier unit and a first reference voltage terminal. The third switching element is connected between the power supply terminal of the second amplifier unit and a second reference voltage terminal.

Abstract: Methods, systems, and devices are described for modulating data for optical transmissions and demodulating data from optical transmissions. During modulation, bits are mapped to symbols using an 8-ary modulation scheme. The modulation scheme may be based on 8 Phase Shift Keying (8-PSK), Dual Polarization 8-PSK, or 7-1 PSK for which one of the symbols is located at or near the origin of the constellation. Streams with the symbol-mapped bits are modulated onto a waveform in the digital domain that is converted into a waveform in the analog domain before is output for conversion to an optical signal. The streams may be filtered at baseband with at least one discrete pulse-shaping filter. During demodulation, pulse-shaped data received from an optical signal and comprising symbol-mapped bits based on the 8-ary modulation scheme is sampled. The sampled data is filtered with at least one discrete pulse-shaping filter, and then equalized and demodulated.

Abstract: An optical transmission system including a transmitting unit to transmit an optical main signal, a receiving unit to receive the optical main signal, and a transmission line through which the optical main signal is transmitted, the optical transmission system includes: an optical transmitter unit configured to be activated or inactivated based on a control signal so as to transmit the control signal, the optical transmitter being included in the transmitting; and an optical receiver configured to receive light with the activate state or the inactivate state of the optical transmitter the optical receiver being included in the receiving unit, wherein the receiving unit regenerates the control signal, based on a power of the received light.

Abstract: To enable optical line terminal to detect input disconnection of optical burst signal accurately in spite of changes of transmission rate of optical-burst signal received from optical network unit, OLT (optical line terminal) includes photo-detector for converting the optical-burst signal received to current signal; preamplifier for converting the current signal to voltage signal; input disconnection detecting circuit for comparing output amplitude of preamplifier with threshold, and for outputting input disconnection signal indicating disconnection of input of the optical-burst signal; and control circuit for controlling conversion gain of preamplifier in a manner that the conversion gain becomes conversion gain corresponding to the transmission rate of the optical-burst signal received, and for controlling input disconnection detecting circuit in a manner that it outputs the input disconnection signal in response to the threshold corresponding to the transmission rate of the optical-burst signal received.

Abstract: An optical detector circuit comprises a photodetector including an optical input for generating a detection signal; a pre-amplifier including a pre-amplifier input and a pre-amplifier output for generating a pre-amplified signal, the pre-amplifier input coupled to the photodetector; and an amplifier including a amplifier input and an amplifier output for generating an output signal, the amplifier input coupled to the pre-amplifier output.

Abstract: Provided is an optical receiving circuit that reduces a distortion of an output pulse width with respect to an input signal by adjusting the division ratio for a voltage applied to resistors in a resistor network.

Abstract: A passive peaking circuit is formed in part from a passive step-down impedance transformer that interconnects the light source driver to the light source. The step-down impedance transformer has impedance that decreases in a continuous or discrete manner in the direction from the light source driver circuit to the light source. The passive peaking circuit peaks the electrical drive signal being delivered from the light source driver circuit to the light source, thereby widening the eye opening.

Abstract: An expurgated pulse position modulation (EPPM) technique can be used to encode information for wireless transmission. Such an EPPM technique can be compatible with a simple receiver architecture, such as including a shift register and pulse position modulation (PPM) decoder. A multi-level EPPM (MEPPM) approach can increase the available symbols in the modulation constellation and can be used to accommodate multiple users or devices concurrently. Interleaving techniques can be used such as to reduce inter-symbol interference. An optical transmitter and an optical receiver can be used, such as including using energy in a visible range of frequencies. In an example, an optical source such as including one or more light emitting diodes can provide visible light for illumination, and the EPPM technique can include using codewords specified to provide a desired dimming level when such codewords are used to intensity modulate the optical source, without perceptible flicker.

Abstract: A frequency offset estimation circuit estimates a frequency offset that indicates a difference between a carrier frequency of a received optical signal and a frequency of a local oscillation light used to recover a transmission signal from the received optical signal. The frequency offset estimation circuit includes: a phase difference detector configured to detect a phase difference due to the frequency offset between a first symbol and a second symbol that is transmitted after the first symbol by a specified symbol interval based on a phase of the first symbol and a phase of the second symbol; an estimator configured to estimate the frequency offset based on the phase difference detected by the phase difference detector; and a symbol interval controller configured to specify the symbol interval based on the frequency offset estimated by the estimator.

Abstract: A communication method in the present disclosure is a communication method for obtaining information from a subject, including: taking a picture of the subject in a picture-taking mode, thereby obtaining image data; performing, after the taking, visible light communication in a visible light communication mode which is a different mode from the picture-taking mode, thereby obtaining visible light data of the subject; and embedding the visible light data obtained, into the image data, and thus saving the visible light data obtained.

Abstract: Described herein are systems and methods for accurately estimating and removing a carrier frequency offset. One exemplary embodiment relates to a system comprising a frequency offset detection circuit detecting a carrier frequency offset in an optical signal, and a frequency testing circuit calculating an estimated frequency offset value of the carrier frequency offset, wherein the frequency testing circuit removes a carrier phase based on the estimated frequency offset value and recovers the optical signal. Another exemplary embodiment relates to a method comprising detecting a carrier frequency offset in an optical signal, calculating an estimated frequency offset value of the carrier frequency offset, removing a carrier phase based on the estimated frequency offset value, and recovering the optical signal.

Abstract: An optical receiver circuit is disclosed in which a number of electrical signals are processed to extract data encoded therein. The electrical signals may be compared during the process to selectively remove one or more waveforms from one or more corresponding electrical signals. Various data signals, each including one or more waveforms, may then be processed to extract the encoded data. The optical receiver circuit reduces, or eliminates, electrical offsets which may be present in one or more of the electrical signals to reduce corresponding errors in the encoded data signals.

Abstract: In the present invention, wasted power consumption caused when a clock and data recovery unit in an optical network unit in a PON system is activated from a power-saving state is reduced and rapid, secure communication is performed. A clock and data recovery unit includes a phase-locked loop that can be set to normal mode or power-saving mode and that includes a voltage-controlled oscillator and recovers a clock signal and a data signal from input signals. The clock and data recovery unit includes a reference clock multiplier circuit that multiplies a reference clock signal and outputs the multiplied reference clock signal; and a frequency training loop that includes the same voltage-controlled oscillator and performs synchronous oscillation training by the voltage-controlled oscillator using the reference clock multiplier circuit before the phase-locked loop transitions from power-saving mode to normal mode.

Abstract: A multi-wavelength optical signal receiving apparatus receives a multi-wavelength optical signal, demultiplexes the received optical signal to convert into an electric signal. The multi-wavelength optical signal receiving apparatus includes a demultiplexing part including a demultiplexer configured to divide the received multi-wavelength optical signal into a plurality of optical signals by wavelength, a photoelectric conversion part to convert the optical signals into electric signals and amplify the electric signals, and at least one lower securing plate configured to couple the parts by an active alignment method. Accordingly, an additional polishing or coating process is not required, which simplifies the manufacturing process, and it is possible to manufacture the apparatus in blocks, thereby increasing mass-productivity.

Abstract: One aspect provides an optical communication system. The system includes an optical-to-digital converter, a frequency estimator and a symbol synchronizer. The optical-to-digital converter is configured to receive an optical OFDM bit stream including an OFDM symbol bearing payload data and a symbol header preceding the OFDM payload data. The frequency estimator is configured to determine a carrier frequency offset of the payload data from the symbol header. The symbol synchronizer is configured to determine a starting location of the payload data within the bit stream by cross-correlating a synchronization pattern within the symbol header with a model synchronization pattern stored by the symbol synchronizer.

Abstract: All-optical phase-modulated data signal regenerator apparatus (10) comprising an optical input (12), an optical signal converter (16), an optical carrier signal source (18), optical signal forming apparatus (20) and an optical output (14). The input (12) is arranged to receive a phase-modulated optical data signal. The signal converter (16) is arranged to receive the data signal and to convert phase modulation of the data signal into a corresponding intensity modulation of an intermediate optical signal. The carrier signal source (18) provides an optical carrier signal.

Abstract: An optical signal receiver tracks local oscillator frequency offset (LOFO) and compensates for the phase distortion introduced in the received signals as a result of utilizing the local oscillator within a coherent detection scheme. This phase distortion is basically a constant phase rotation caused by the LOFO and implementation of the receiver using coherent detection and a digital interferometer instead of a conventional (yet complex) carrier phase estimation or recovery scheme. With an optical receiver implemented in this manner, the requirement of using a precise local oscillator laser with low frequency offset is less important.

Abstract: A comparator (11) outputs, out of an electrical signal input from a trans impedance amplifier (TIA) via a coupling capacitor, pulses having amplitudes equal to or larger than a reference value as a comparison output signal (Cout). An analog holding circuit (12) charges a holding capacitor with each pulse contained in the comparison output signal (Cout) and also removes a DC voltage obtained by the charging via a discharging resistor, thereby generating a holding output signal (Hout) that changes in accordance with the presence/absence of input of an optical signal. This allows to perform an autonomous operation without any necessity of an external control signal and properly detect the presence/absence of input of an optical signal.

Abstract: An optical level control apparatus includes an input port, an output port, an optical device to assume a state of outputting light inputted to the input port from the output port and a state of not outputting the light inputted to the input port from the output port; a detector to detect an intensity of the light inputted to the input port, and a control unit to detect an input of an optical burst signal to the input port on the basis of a result of detecting the intensity of the light and to control the optical device so that the signal, in which to eliminate a field extending up to an elapse of a period of first time equal to or shorter than laser ON time period of the signal from a head of the signal with its input being detected, is output from the output port.

Abstract: Disclosed are a method and device for increasing the adaptability of light intensity, which relate to the field of photoelectric communications. The method comprises: providing several stages of load resistors in the device, the device collecting voltage values, calculating the average value of all the collected voltage values when a preset number of voltage values which meet the requirements are collected, setting a voltage according to the average value and judging whether the set voltage meets preset requirements; and if yes, collecting data according to the set voltage; otherwise switching a load resistor according to a preset rule, wherein the load voltage may affect the voltage collection. The present invention has the beneficial effects of: improving the adaptability of a screen to light intensity during optical signal collection, and at the same time being able to reduce the error rate.

Abstract: In one embodiment, an optical receiver has a bulk dispersion compensator and a butterfly equalizer serially connected to one another to perform dispersion-compensation processing and electronic polarization de-multiplexing. The bulk dispersion compensator has a relatively large dispersion-compensation capacity, but is relatively slow and operates in a quasi-static configuration. The butterfly equalizer has a relatively small dispersion-compensation capacity, but can be dynamically reconfigured on a relatively fast time scale to track the changing conditions in the optical-transport link. The optical receiver has a feedback path that enables the configuration of the bulk dispersion compensator to be changed based on the configuration of the butterfly equalizer in a manner that advantageously enables the receiver to tolerate larger amounts of chromatic dispersion and/or polarization-mode dispersion than without the use of the feedback path.

Abstract: The method and apparatus as disclosed herein allows the user to input conditions for a communications link, set characteristic values of a photon-counting detector array, simulate the resulting link, observe a summary analysis of the simulated detector and link activity, and extract a record of the detector activity (e.g. each photon counted) making it available for further analysis.

Abstract: An optical component contains a tunable laser. The tunable laser provides an optical local oscillator signal, and the tunable laser is directly modulated to provide a modulated optical data signal. In this manner we have optimization of the channel wavelength and obtain an optimized electrical and optical bandwidth utilization. Furthermore, a method for data processing is suggested.

Abstract: A completely digital optical receiver is provided. The optical receiver includes a photodiode configured to provide a photodiode output responsive to an on-off keyed (OOK) optical input. Two or more digital inverters connected in series with each other are configured to receive the photodiode output and provide an amplified digital output. A digital clock and data recovery (CDR) circuit receives the amplified digital output and provides a clock output and a data output. A digital photodiode discharging circuit is connected to the photodiode and controlled by the clock output of the CDR circuit.

Abstract: An active optical beam shaping system includes a first deformable mirror arranged to at least partially intercept an entrance beam of light and to provide a first reflected beam of light, a second deformable mirror arranged to at least partially intercept the first reflected beam of light from the first deformable mirror and to provide a second reflected beam of light, and a signal processing and control system configured to communicate with the first and second deformable mirrors. The first deformable mirror, the second deformable mirror and the signal processing and control system together provide a large amplitude light modulation range to provide an actively shaped optical beam.

Abstract: Provided is an optical receiver including a first delay interferometer, a second delay interferometer, and an input light splitting portion for inputting modulated light. The first delay interferometer includes a first light splitting portion for splitting the input light into first light and second light, a first reflecting portion and a second reflecting portion for causing the first light and the second light to return to the first light splitting portion. The second delay interferometer includes a second light splitting portion for splitting the input light into third light and fourth light, a third reflecting portion and a fourth reflecting portion for causing the third light and the fourth light to return to the second light splitting portion. A region between the first light splitting portion and the second reflecting portion intersects with a region between the second light splitting portion and the fourth reflecting portion.

Abstract: In a coherent optical receiver, sufficient demodulation becomes impossible and consequently receiving performance deteriorates if an inter-channel skew arises, therefore, a coherent optical receiver according to an exemplary aspect of the invention includes a local light source, a 90° hybrid circuit, an optoelectronic converter, an analog to digital converter, and a digital signal processing unit; wherein the 90° hybrid circuit makes multiplexed signal light interfere with local light from the local light source, and outputs a plurality of optical signals separated into a plurality of signal components; the optoelectronic converter detects the optical signals and outputs detected electrical signals; the analog to digital converter quantizes the detected electrical signals and outputs quantized signals; the digital signal processing unit includes a skew compensation unit for compensating a difference in propagation delay between the plurality of signal components, and an FFT operation unit for performing a fas

Abstract: In an optical communication system, an optical transmitter changes operational physical layer parameters to meet future target throughput for the optical communication system. The optical transmitter communicates the upcoming change to the optical receiver in a message that used current physical layer parameters. The optical transmitter provides sufficient time to the optical receiver to adjust reception functions of the receiver, including polarization based demodulation scheme. In some implementations, the optical transmitter performs the transition to a new physical layer transmission format without waiting for an acknowledgement from the optical receiver.

Abstract: A wavelength division multiplexing passive optical network (WPON) comprising an optical line terminal (OLT) and a plurality of optical network units (ONUs) coupled to the OLT via a power optical splitter. The OLT is configured to monitor wavelengths in use by the ONUs and to divide upstream traffic from the ONUs into multiple channels using tunable filters. Also disclosed is an OLT for a PON, the OLT comprising a plurality of receivers and a plurality of tunable filters corresponding to each of the receivers. The OLT also comprises channel control logic coupled to the tunable filters, wherein the channel control logic is configured to detect a plurality of wavelengths in use for upstream traffic in the PON and to divide the upstream traffic into multiple channels using the tunable filters. Included is a method for managing upstream traffic in a PON, the method comprising monitoring, by a processor, wavelengths in use for upstream traffic in the PON.

Abstract: An optical communication system, a transmitter, a receiver, and methods of operating the same are provided. In particular, a transmitter is disclosed as being configured to encode optical signals in accordance with a multi-level coding scheme. The receiver is configured to provide receive and decode to the optical signals received from the transmitter. One or both of the receiver and transmitter are configured to compensate for non-idealities or non-linearities introduced into the communication system by optical components of the system.

Abstract: An optical receiver is provided with a photoelectric converter that outputs an electrical signal according to light that is received by a light-receiving region. The optical receiver is provided with a condensing lens and optical filter that are located in an optical path from where signal light enters towards the light-receiving region. The condensing lens condenses the signal light onto the light-receiving region. The optical filter reflects light having a first wavelength that is included in the signal light using a front surface thereof and reflects light having a second wavelength that is included in the signal light using a rear surface thereof that faces the front surface so that the light is emitted through the front surface.

Abstract: A digital coherent optical receiver includes a processor that is operative to separate electric signals obtained by converting an optical signal into a horizontal signal component and a vertical signal component; to generate a histogram of the horizontal signal component and the vertical signal component as outputs of the equalizing filter; and to determine a presence/absence of local convergence based on distribution of the histogram of the horizontal signal component and the histogram of the vertical signal component.

Abstract: The present invention provides a signal detection method, including: receiving, by a frequency mixer, wavelength division multiplexing signals and a local oscillator signal, where a wavelength of the local oscillator signal and a wavelength of a target signal in the wavelength division multiplexing signals are the same; a frequency mixer performs interference on the wavelength division multiplexing signals through the local oscillator signal to obtain a coherent signal formed by the local oscillator signal and the target signal; sending the coherent signal to a transimpedance amplifier for amplification to obtain a voltage signal; and obtaining the power of the target signal according to a power amplitude of the voltage signal.

Abstract: To enable signal position detection, frequency offset compensation, clock offset compensation, and chromatic dispersion amount estimation in a communication system based on coherent detection using an optical signal, even on a signal having a great offset in an arrival time depending on a frequency due to chromatic dispersion. An optical signal transmitting apparatus generates specific frequency band signals having power concentrated on two or more specific frequencies and transmits a signal including the specific frequency band signals. An optical signal receiving apparatus converts a received signal into a digital signal, detects positions of the specific frequency band signals from the converted digital signal, estimates frequency positions of the detected specific frequency band signals, and detects a frequency offset between an optical signal receiving apparatus and an optical signal transmitting apparatus.

Abstract: An apparatus comprises an optical transmitter; an optical detector configured to receive optical signals from an optical fiber; an optical splitter having a first port, a second port coupled to the optical detector by the optical fiber, and a third port coupled to the optical transmitter; and a two stage amplifier system connected to an output of the optical detector. An input surface of the optical detector may have a diameter that is substantially equal to a diameter of a core in the optical fiber. The diameter of the input surface of the optical detector reduces capacitance and reduces signal distortion. The optical splitter may be configured to receive a first optical signal at the first port. The optical splitter may be configured to send the first optical signal to the second port and send a second optical signal received at the third port to the first port.

Abstract: A transmitter in an optical communications system includes a digital signal processor for processing a data signal to generate a sample stream encoding successive symbols in accordance with a constrained phase modulation scheme having a constellation of at least two symbols and a modulation phase constrained to a phase range spanning less than 4?. A digital-to-analog converter converts the sample stream into a corresponding analog drive signal. A finite range phase modulator modulates a phase of a continuous wavelength channel light in accordance with the analog drive signal, to generate a modulated channel light for transmission through the optical communications system. A receiver in the optical communications system includes an optical stage for detecting phase and amplitude of the modulated channel light and for generating a corresponding sample stream, and a digital signal processor for processing the sample stream to estimate each successive symbol of the modulated channel light.

Abstract: A system and a method are disclosed for receiving an infrared signal on a mobile device. The mobile device receives an infrared signal by creating an intermediate bitstream based on the received infrared signal. The intermediate bitstream is trimmed, downsampled, and demodulated in the time domain. The intermediate bitstream is then converted into a raw infrared code. The received bitstream is processed in a software layer, enabling the mobile device to process infrared signals without the use of additional hardware configured on the mobile device.

Abstract: In general, this disclosure relates to optical network devices with support for multiple physical layer transport standards. An optical network device may include an optical receiver that can be adaptively configured to support different physical layer transport standards. For example, the optical receiver may include a photodiode and a control unit to adjust a characteristic of the photodiode to support different optical physical layer transport standards on an adaptive basis. For example, the control unit may adjust the photodiode characteristic to prevent an overload condition when an optical signal is received according to the physical layer access standard.

Abstract: A parameter of an adaptive filter is optimized so that inter-symbol interference having an amount corresponding to an inserted fixed filter remains.

Abstract: An optical receiver includes: an interference unit generating a first interference light signal (ILS1) and a second interference light signal (ILS2) with an approximately inverse phase to that of the first interference light signal, by causing a received light signal to interfere with local oscillator light; a first interference light subtraction unit generating a first interference light subtraction signal (ILSS1) representing the difference between signals obtained by photoelectric conversion of ILS1 and a local oscillator light proportional signal having light intensity based on the light intensity of the local oscillator light; a second interference light subtraction unit generating a second interference light subtraction signal (ILSS2) representing the difference between a signal obtained by photoelectric conversion of ILS2 and the signal obtained by photoelectric conversion of the local oscillator light proportional signal; and a difference output unit outputting a signal representing the difference bet

Abstract: A method, an apparatus and a system for detecting a connection status of an optical fiber jumper are provided in the embodiments of the present invention. The method for detecting a connection status of an optical fiber jumper includes: judging a connection status of a second port and a first port according to whether an optical signal sent by the first port to the second port through a first optical fiber is received, wherein the first optical fiber is connected to two ends of an optical fiber jumper, and the two ends of the optical fiber jumper are connected to the first port and the second port respectively; and obtaining a port identification corresponding to the first port according to the optical signal if the optical signal is received.

Abstract: A system and method of digitizing an analog signal without an amplitude channel is disclosed. The system and method includes receiving an analog signal comprising a voltage v(t) and a frequency f1, producing a series of optical pulses at a sampling frequency f2 with a pulsed laser, splitting the series of optical pulses into a first optical signal and an optical reference signal, phase modulating the first optical signal with the analog signal to produce a sampled optical signal such that phase shifts between adjacent samples in the sampled optical signal does not exceed ? radians, and receiving the sampled optical signal and the optical reference signal at a photonic signal processor.

Abstract: According to one embodiment, a photo detector-combined illuminance sensor includes a circuit for a Photo Detector (PD) function to detect the illuminance of the ambient environment. The illuminance sensor operates under the control of a controller in a visible light communication terminal. When an optical signal detected by the illuminance sensor is a visible light communication signal, the controller switches to cause the illuminance sensor to operate as the photo detector for the visible light communication in a visible light communication mode.

Abstract: A coherent optical communication device includes a demodulator configured to demodulate a reception signal; a local oscillator light optical source configured to generate local oscillator light used for demodulating the reception signal; a memory configured to store wavelength information; and a controller configured to control the local oscillator light optical source when the demodulator cannot receive the reception signal, so that a wavelength of the local oscillator light generated in the local oscillator light optical source is changed to a wavelength specified by the wavelength information stored in the memory.

Abstract: A method, a network, and a node each implement the transmission of Automatic Protection Switching (APS) switching coordination bytes across an OTN network. A working signal and a protection signal are received, one of which is designated as an active signal. The active signal is encapsulated in an Optical channel Data Unit (ODU) signal. APS switching coordination bytes from the working and protection signals are placed in an overhead segment of the ODU signal. The ODU signal is transmitted into and received from an Optical Transport Network (OTN) network. The working and protection signals are recreated based on the active signal encapsulated in the ODU signal and the APS switching coordination bytes in the overhead segment. The recreated working and protection signals are transmitted. In this manner, a single ODU signal may be used to transmit both the working and protection signals.