An optical transmission device and an optical communication system being capable of coping with various installation forms of a transponder in a unit of optical fiber transmission path are provided. The optical transmission device is installed inside a station building. First and second interface units are connected to first and second fiber transmission paths accommodated in a submarine optical fiber cable. A first fiber transmission path mediates an optical signal to be transmitted between the first interface unit and a first transponder. A second fiber transmission path mediates an optical signal to be transmitted between the second interface unit and a second transponder.

A method is described in which a loss of spectrum in an optical signal having an optical signal spectrum is detected. The optical signal is transmitted from a first node to a second node. In response to detecting the loss of spectrum in the optical signal, at least one idler carrier without data imposed is supplied into the optical signal spectrum transmitted from the first node to the second node, the optical signal spectrum encompassing a frequency band including a plurality of optical channels, the idler carrier being amplified stimulated emission light having a frequency corresponding to a first optical channel of the plurality of optical channels.

A method of loading a fiber optic transport system includes detecting optical power in a frequency sub-band of optical spectrum, wherein the frequency sub-band includes data-bearing channels and at least one control channel; measuring optical power in the frequency sub-band; and adjusting optical power of the at least one control channel based on the measured optical power, wherein the optical power is adjusted through one of changing a current of control channel lasers and controlling a set of fast optical attenuators.

A multiplexer inserts a dummy signal light into a main signal. A light intensity monitor acquires the intensity of the light of each wavelength of a light output from a wavelength selective switch. A light source controller controls the insertion of the dummy signal light into the main signal, and release of the insertion. A difference calculator calculates the difference between a first light intensity that has been acquired in a state in which the dummy signal light is inserted into the main signal and a second light intensity that has been acquired in a state in which the dummy signal light is not inserted into the main signal. An insertion loss calculator calculates an insertion loss in the wavelength selective switch based on the calculated difference. An insertion loss controller controls the insertion loss in the wavelength selective switch based on the calculated insertion loss.

An optical transmission device and an optical communication system being capable of coping with various installation forms of a transponder in a unit of optical fiber transmission path are provided. The optical transmission device is installed inside a station building. First and second interface units are connected to first and second fiber transmission paths accommodated in a submarine optical fiber cable. A first fiber transmission path mediates an optical signal to be transmitted between the first interface unit and a first transponder. A second fiber transmission path mediates an optical signal to be transmitted between the second interface unit and a second transponder.

A method of loading a fiber optic transport system includes adding one or more control channels to an optical fiber having one or more channels, wherein each of the control channels comprises a pair of signals that are cross-polarized and each of the pair of signals is at a different frequency from one another; measuring optical power on the optical fiber; and adjusting optical power of the one or more control channels based on the measured optical power.

A dummy-light generating device includes a continuous wave (CW) light source that outputs CW light, a modulated-light generating unit that generates, using the CW light, first intensity-modulated light subjected to intensity modulation and second intensity-modulated light delayed by a half time of a modulation cycle of the first intensity-modulated light with respect to the first intensity-modulated light and having a polarization state e different from a polarization state e of the first intensity-modulated light, and a polarization combiner that performs polarization combination of the first intensity-modulated light and second intensity-modulated light and outputs light after the polarization combination as dummy light.

When a terminal point of an optical signal propagating through a submarine cable is extended in an optical transmission system, development man-hours and costs are increased. Thus, the optical transmission system according to the present invention includes: a first optical device configured to be connected to a plurality of first fibers and a second fiber associated with each of the plurality of first fibers; and a second optical device configured to be connected to the second fiber, the first optical device and the second optical device each include an optical function block, and the optical function block is configured to achieve an optical function defined for each of the plurality of first fibers.

A method is described in which a database is monitored. The database includes information specifying allocations of time periods in which a first optical carrier corresponding to a first optical channel will not be supplying encoded first data into output optical signals being transmitted from a first node to a second node. An idler carrier being amplified stimulated emission light having a frequency corresponding to the first optical channel is supplied into the output optical signals transmitted from the first node to the second node during the time periods in which the first optical carrier will not be supplying encoded first data into the output optical signals.

A method is described in which a loss of spectrum in an optical signal having an optical signal spectrum is detected. The optical signal is transmitted from a first node to a second node. In response to detecting the loss of spectrum in the optical signal, at least one idler carrier without data imposed is supplied into the optical signal spectrum transmitted from the first node to the second node, the optical signal spectrum encompassing a frequency band including a plurality of optical channels, the idler carrier being amplified stimulated emission light having a frequency corresponding to a first optical channel of the plurality of optical channels.