An optical transmitter and a method for driving the optical transmitter include generating a modulated signal having an operation frequency corresponding to a communication channel, obtaining a first optical signal using passing a portion of the modulated signal through a first optical path, obtaining a second optical signal using passing another portion of the modulated signal through a second optical path having a different spectral response curve from that of the first optical path, converting the first optical signal to a first electrical signal, converting the second optical signal to a second electrical signal, obtaining an error signal between the first and second electrical signals, finding a maximum of the error signal by varying the operation frequency over a predetermined frequency range of the communication channel, and determining that the operation frequency is matched to a passband of a frequency reshaper when the error signal reaches the maximum.

A test controller of a transmitting-side optical wavelength multiplexing transmission apparatus of the present invention includes a wavelength tunable filter controller configured to control a center wavelength and a wavelength band of an optical signal that a wavelength tunable filter transmits; and a test transponder controller configured to control a wavelength band of a test optical signal generated by a test transponder and a wavelength interval between the test optical signal and the optical signal that the wavelength tunable filter transmits. A test controller of a receiving-side optical wavelength multiplexing transmission apparatus of the present invention includes a wavelength tunable filter controller configured to control a center wavelength and a wavelength band of an optical signal that a wavelength tunable filter transmits; and a test transponder controller configured to control a center wavelength and a wavelength band of a test optical signal received by a test transponder.

An optical transmitter using multiplexed optical signals increases in cost and in size in order to control an optical carrier frequency with high precision, therefore, an optical transmitter according to an exemplary aspect of the invention includes optical signal generating means for adding a first optical component to a first optical carrier and adding a second optical component to a second optical carrier; multiplexing means for multiplexing the first optical carrier and the second optical carrier to generate a multiplexed optical signal; monitoring means for monitoring the multiplexed optical signal to detect a monitor signal having a difference frequency between the first optical component and the second optical component; and controlling means for controlling a carrier frequency of at least one of the first optical carrier and the second optical carrier according to the monitor signal.

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 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.

A wavelength control system, method, and apparatus are described in the present disclosure. An example method include: adjusting powers of subcarriers on a super channel to a same power, where the subcarriers of the super channel includes consecutive subcarriers, a subcarrier i1, a subcarrier i, and a subcarrier i+1; obtaining Q values of the subcarrier i1 and the subcarrier i+1, where the Q values indicate performance of the subcarriers; calculating a Q value difference between the Q value of the subcarrier i+1 and the Q value of the subcarrier i1, and calculating a difference between the Q value difference and a pre-obtained reference value of the subcarrier i; determining whether the absolute value of the difference is not less than the pre-obtained allowable frequency offset value, and adjusting a center wavelength of the subcarrier i according to the difference.

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).

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.

Devices, computer-readable media and methods are disclosed for determining reachability for a wavelength connection in a telecommunication network. For example, a processor deployed in a telecommunication network may calculate a fiber loss on a link in the telecommunication network using optical power measurements and determine that a destination node of a wavelength connection is not reachable via a path that includes the link based upon the fiber loss of the link that is calculated. In one example, the determining is based upon a number of links in the path, an effective fiber loss for each link in the path, a penalty for nodes in the path, and an acceptable loss value. The processor may further perform a remedial action in response to determining that the destination node of the wavelength connection is not reachable via the path.

A receiving apparatus includes a first processor configured to compensate, in a perturbation back-propagation (PBP) scheme, waveform degradation of an optical signal by traveling an optical transmission line due to a nonlinear optical effect; a memory; and a second processor coupled to the memory and the second processor configured to change a gamma coefficient to be used in the PBP scheme, measure reception quality of the optical signal for each of gamma coefficients obtained by the changing, specify a gamma coefficient in accordance with the reception quality from among the gamma coefficients obtained by the changing, and set the specified gamma coefficient as a parameter of the PBP scheme.