Abstract: A transmission device includes: optical transmitters configured to transmit optical signals of different wavelengths; optical couplers configured to multiplexing the optical signals transmitted from the optical transmitters; and a wavelength selective switch configured to multiplex multiplexed optical signals obtained by multiplexing by the couplers, wherein optical signals, a wavelength interval between which is less than a predetermined value, are transmitted to separate optical couplers of the optical couplers, among the optical signals.

Abstract: A transmitting device includes a transmitter configured to transmit signal light to an external receiver over a medium included in a transmission line; and a controller configured to control a transmission level of the signal light in accordance with a reception level of probe light which is input from the receiver over the medium in the transmission line.

Abstract: A switchable optical amplifier includes: a first optical amplifier; a second optical amplifier; and an optical switch which includes first and second input ports and first and second output ports, the optical switch that switches between a first connection state where the first input port and the first output port are in an optical connection and the second input port and the second output port are in a no optical connection and a second connection state where the first input port and the second output port are in an optical connection and the second input port and the first output port are in an optical connection, wherein an output of the first optical amplifier is optically coupled to the first input port of the optical switch, an input of the second optical amplifier is optically coupled to the second output port of the optical switch.

Abstract: A transmission apparatus includes: an amplifier controller configured to determine a target value for an average optical input power of a transmitting amplifier in a transmitting-side apparatus, based on an index based on a quality of transmission from an output of the transmitting amplifier to an output of a receiving amplifier in a receiving-side apparatus; and a pre-emphasis controller configured to determine amounts of adjustment of transmission optical powers for respective wavelengths, based on the target value and per-wavelength reception optical powers at the output of the receiving amplifier.

Abstract: An optical amplification apparatus includes an optical amplification medium configured to receive a first light signal from an end of the optical amplification medium and a second light signal from the other end of the optical amplification medium in opposite directions, the first and second light signals being branched from a light signal, an excitation light source configured to supply excitation light to the optical amplification medium through a multiplexer, a monitor configured to monitor the first and second light signals input to the optical amplification medium, respectively and to output monitoring signals respectively, and a controller configured to control the excitation light source in accordance with the monitoring signals.

Abstract: An optical amplifier includes an optical amplifying unit, a splitting unit, and a loss adjusting unit. The optical amplifying unit provides gain to wavelength multiplexed light received from a transmission line, to amplify light intensity. The splitting unit splits the amplified wavelength multiplexed light. The loss adjusting unit adjusts loss provided to each wavelength of a first portion or the split wavelength multiplexed light based on the gain.

Abstract: An optical transmission apparatus includes an optical amplifier configured to amplify a wavelength-division multiplexed signal light using an amplifying medium doped with a rare earth ion, a first optical transmitter configured to output a wavelength of a dual-polarization-multiplexed signal to a short wavelength side of an amplification band of the optical amplifier, a second optical transmitter configured to output a wavelength of a non polarization-multiplexed signal to a long wavelength side of the amplification band of the optical amplifier, and an optical multiplexer configured to input a wavelength-division multiplexed signal to the optical amplifier, the wavelength-division multiplexed signal comprising the non polarization-multiplexed signal and the dual-polarization-multiplexed signal.

Abstract: In an optical amplification apparatus an optical amplifier amplifies an optical signal at set gain. An equalizer changes loss of the amplified optical signal according to wavelengths. A processor controls the equalizer so as to make the equalizer have a loss-wavelength characteristic corresponding to a gain tilt of the optical amplifier which occurs according to the set gain.

Abstract: An optical transmission device includes a receiver that receives first light, a transmitter that outputs second light, a memory, a processor coupled to the memory, configured to control a first optical level of the second light in such a way that a second optical level calculated based on an optical level of the received first light and an optical level of the second light that is output from the transmitter becomes a predetermined target value, a combiner that combines the received first light and the second light for which the first optical level is controlled by the processor, and an amplifier that amplifies the combined light.

Abstract: A communication system including: a transmission apparatus configured to modulate a first light by using a first signal to be transferred and a second signal having a frequency different from a frequency of the first signal so as to generate a first optical signal, modulate a second light by using a third signal to be transferred and a fourth signal having a frequency different from a frequency of the third signal so as to generate a second optical signal, polarization-multiplex the first optical signal and the second optical signal, and transmit a polarization-multiplexed optical signal in which the first optical signal and the second optical signal are polarization-multiplexed, each of the first light and the second light being polarized; and a measuring apparatus configured to measure powers of the second signal and the fourth signal which are included in the polarization-multiplexed optical signal transmitted from the transmission apparatus.

Abstract: An optical channel monitor includes: a first optical device to include first, second and third optical ports, light input through the first optical port being led to the second optical port, light input through the second optical port being led at least to the third optical port; a second optical device to include fourth, fifth and sixth optical ports, light input through the fourth optical port being led to the fifth optical port, light input through the fifth optical port being led at least to the sixth optical port; an optical filter to include seventh and eighth optical ports optically connected to the second and fifth optical ports, respectively, a specified wavelength being transmitted between the seventh and eighth optical ports; a first photo detector to detect light output from the sixth optical port; and a second photo detector to detect light output from the third optical port.

Abstract: A bidirectional monitor module includes a 2×2 optical coupler configured to output input light that is input from a first port to a second port and drop the input light input from the first port to a third port and also output input light that is input from the second port to the first port and drop the input light input from the second port to a fourth port; an optical output unit configured to output one of light that is dropped and output from the third port and light that is dropped and output from the fourth port; and a monitor unit configured to monitor optical power of the light output from the optical output unit.

Abstract: An excitation light source, for Raman amplification, includes a polarization beam splitter (PBS) for splitting a laser beam from an excitation laser into two polarization components, and a polarization beam combiner (PBC) for combining the two polarization components, and a time difference generator provided between PBS and PBC. The time difference generator generates a difference in propagation time between the two polarization components.

Abstract: There is provided an optical transmission apparatus including: a transmitter to output an optical signal to be transferred to other optical transmission apparatus; a first dummy light source to generate first dummy light having a wavelength which is not included in an optical signal received from other optical transmission apparatus; a first wavelength-multiplexer to wavelength-multiplex the optical signal received from other optical transmission apparatus, the optical signal output from the transmitter, and an optical signal with a wavelength, of the first dummy light, which is not included in the optical signal received from other optical transmission apparatus and in the optical signal output from the transmitter; and an optical amplifier to amplify an optical signal multiplexed by the first wavelength-multiplexer.

Abstract: A transmission apparatus includes: an amplifier controller configured to determine a target value for an average optical input power of a transmitting amplifier in a transmitting-side apparatus, based on an index based on a quality of transmission from an output of the transmitting amplifier to an output of a receiving amplifier in a receiving-side apparatus; and a pre-emphasis controller configured to determine amounts of adjustment of transmission optical powers for respective wavelengths, based on the target value and per-wavelength reception optical powers at the output of the receiving amplifier.

Abstract: A transmission device includes: optical transmitters configured to transmit optical signals of different wavelengths; optical couplers configured to multiplexing the optical signals transmitted from the optical transmitters; and a wavelength selective switch configured to multiplex multiplexed optical signals obtained by multiplexing by the couplers, wherein optical signals, a wavelength interval between which is less than a predetermined value, are transmitted to separate optical couplers of the optical couplers, among the optical signals.

Abstract: An OSNR measuring device n OSNR measuring device includes an input port to which a signal light is given; a wavelength filter which includes a variable passband, and selectively takes out an optical component corresponding to a signal optical wavelength to be measured from the signal light; a wavelength control circuit which controls the passband of the wavelength filter; a delay interferometer which branches a light output from the wavelength filter and delays one of the branched lights with respect to the other branched light and in which the branched lights are made to interfere with each other; a photodetector which detects a power of a delay interference light output; and an OSNR calculation circuit which calculates, based on a bandwidth of a passband of the wavelength filter and the power of the delay interference light, an optical signal to noise ratio of a signal optical wavelength to be measured.

Abstract: A transmitting device includes a transmitter configured to transmit signal light to an external receiver over a medium included in a transmission line; and a controller configured to control a transmission level of the signal light in accordance with a reception level of probe light which is input from the receiver over the medium in the transmission line.

Abstract: An OSNR monitor device includes an optical receiver including a delay interferometer which inputs an optical signal in accordance with a given bandwidth and outputs two optical signals and causes the optical signals to interfere with each other and optical detectors which outputs currents in accordance with optical powers of the optical signals output from the interferometer, an optical power monitor configured to obtain the optical powers of the optical signals received by the optical detectors included in the optical receiver, and an OSNR calculator configured to calculate an optical signal-to-noise ratio in accordance with the optical powers obtained from the optical power monitor and the reception bandwidth.

Abstract: A bidirectional monitor module includes a 2×2 optical coupler configured to output input light that is input from a first port to a second port and drop the input light input from the first port to a third port and also output input light that is input from the second port to the first port and drop the input light input from the second port to a fourth port; an optical output unit configured to output one of light that is dropped and output from the third port and light that is dropped and output from the fourth port; and a monitor unit configured to monitor optical power of the light output from the optical output unit.