Abstract: A method of registering an optical network unit (ONU) in an optical line terminal (OLT). The OLT determines a lane to be used by the ONU based on a transmission rate supported by the ONU, combines or distributes data of a dataflow based on a rate of the lane by comparing the rate of the lane to a rate of the dataflow of a media access control (MAC) client interface, and, when the OLT and the ONU are connected through multiple lanes, transmits and receives data between the OLT and the ONU through channel bonding for more effective use of a network.

Abstract: Provided is a phase error compensating apparatus. The phase error compensating apparatus may include a waveguide array disposed between a first free propagation region and a second free propagation region and configured to allow a light signal passed through the first free propagation region to move toward the second free propagation region, in which a length of each of the waveguides included in the waveguide array may be adjusted to compensate for a phase error of light signals passed through the waveguides.

Abstract: Provided is a phase error compensating apparatus. The phase error compensating apparatus may include a waveguide array disposed between a first free propagation region and a second free propagation region and configured to allow a light signal passed through the first free propagation region to move toward the second free propagation region, in which a length of each of the waveguides included in the waveguide array may be adjusted to compensate for a phase error of light signals passed through the waveguides.

Abstract: An optical fiber cable of a mobile fronthaul system based on a radio over fiber (RoF), which includes a control apparatus for monitoring an analog optical link according to an exemplary embodiment, may be monitored. The monitoring control apparatus may include an optical signal monitor to monitor an optical signal passing through an optical fiber cable, and a system controller to control the optical signal based on a result of the monitoring. The optical signal monitor may calculate an average optical power, carrier-to-noise ratio (CNR), and a size of a nonlinear component from an electrical signal, which has been acquired from the optical signal. Then, the optical signal monitor may control the calculated average optical power, CNR, and nonlinear component.

Abstract: An optical line terminal (OLT) of an Ethernet passive optical network (EPON) and an optical network unit (ONU) of the EPON. The OLT includes a frame allocator configured to allocate a plurality of frames to each of a plurality of wavelengths, and a frame outputter configured to output the frames through the wavelengths, in which each of the frames includes a frame sequence number corresponding to a sequence order of each frame. The ONU includes a frame receiver configured to receive a plurality of frames each including a frame sequence number and a frame arranger configured to arrange the frames in order based on the frame sequence number.

Abstract: Provided is an analog optical transmission system using a dispersion management technique. The analog optical transmission system may include a digital unit (DU) pool including a plurality of DUs to transmit an optical signal; a plurality of radio units (RUs) to receive the optical signal; and one or more dispersion management apparatus to remove a signal distortion component caused by an interaction between a chirp and chromatic dispersion by compensating for the chromatic dispersion before the plurality of RUs receives the optical signal that is transmitted from the DU pool.

Abstract: An optical signal transmission system and method of allocating center frequencies of intermediate frequency (IF) carriers in a frequency division multiplexing (FDM) optical fiber link. The optical signal transmission method includes determining a center frequency interval between modulated signals based on a bandwidth of the modulated signals or a center frequency of a modulated signal having a lowest center frequency, among the modulated signals, reallocating center frequencies to the modulated signals based on the center frequency interval between the modulated signals, and converting the modulated signals reallocated the center frequencies from electrical signal into optical signal and transmitting the optical signal.

Abstract: A radio-over-fiber (RoF) transmission system includes at least one baseband unit (BBU) connected to a core network of a service provider that provides a mobile Internet service, an optical line terminal (OLT) configured to convert a radio signal received from the at least one BBU into an optical signal, an optical distribution network (ODN) comprising an optical fiber and an optical splitter, at least one optical network unit (ONU) configured to receive the optical signal from the OLT via the ODN and convert the optical signal into a radio signal, and at least one remote radio head (RRH) configured to receive the radio signal from the at least one ONU and output the radio signal via a plurality of antennas.

Abstract: An optical line terminal (OLT) and an optical network unit (ONU) configured to generate a plurality of fragments by fragmenting a media access control (MAC) frame and to transmit the plurality of generated fragments, when a length of the MAC frame is greater than or equal to a maximum transmission unit (MTU).

Abstract: A flexible printed circuit board (FPCB) for an optical module includes: a signal via pad connected with a signal lead pin of the optical module; a ground layer spaced apart from the signal via pad; an isolation gap formed between the signal via pad and the ground layer; and a protective layer which is formed at a portion that comprises the isolation gap, and which, when connected with the signal via pad, compensates for parasitic inductance caused by a protruding signal lead pin.

Abstract: An apparatus for transmitting a control signal in a radio-over-fiber (RoF)-based mobile fronthaul includes: a data channel transmitter configured to generate a data signal at a preassigned frequency or wavelength; a control channel transmitter configured to generate a control signal at a designated frequency or wavelength that is shared with other apparatuses; and a combiner configured to combine the data signal with the control signal.

Abstract: An optical demultiplexing apparatus and method for multi-carrier distribution are provided. The optical demultiplexing apparatus may include a demultiplexer and a carrier distributor. The optical demultiplexing apparatus and method allow efficient demultiplexing of a multi-carrier light source by using a single demultiplexer even when a carrier spacing of the light source varies.

Abstract: An optical fiber cable of a mobile fronthaul system based on a radio over fiber (RoF), which includes a control apparatus for monitoring an analog optical link according to an exemplary embodiment, may be monitored. The monitoring control apparatus may include an optical signal monitor to monitor an optical signal passing through an optical fiber cable, and a system controller to control the optical signal based on a result of the monitoring. The optical signal monitor may calculate an average optical power, carrier-to-noise ratio (CNR), and a size of a nonlinear component from an electrical signal, which has been acquired from the optical signal. Then, the optical signal monitor may control the calculated average optical power, CNR, and nonlinear component.

Abstract: A polarization control device in accordance with an exemplary embodiment of the present invention may include a first polarization converter for converting a polarization angle of an input optical signal in response to first control voltages, a second polarization converter for converting a polarization angle of an input optical signal in response to second control voltages, and a third polarization converter for converting an optical signal received from the first polarization converter or the second polarization converter into a first output optical signal having a linear polarization state and outputting the first output optical signal.

Abstract: An optical transmission apparatus includes: a transmission light source configured to generate single-mode light of a specific wavelength; a power coupler configured to split the light generated by the transmission light source into a plurality of light sections; at least one modulator configured to modulate an electrical signal carrying different data into at least one optical signal using the light section from the power coupler; and a mode multiplexer configured to convert the modulated optical signal into a different mode, and to transmit the mode-converted optical signal to a fiber.

Abstract: An optical pumping apparatus for few-mode fiber amplification is provided. The optical pumping apparatus includes an optical pump source configured to generate an optical pump; an optical power divider configured to divide an optical power of the optical pump from the optical pump source so as to output several optical pumps with uniformly distributed optical power; and a modal multiplexer configured to receive the optical pumps from the optical power divider through a plurality of single-mode fibers, multiplex the received optical pumps, apply a multiplexed optical pump to each mode of a few-mode fiber (FMF) amplifier, and adjust a gain difference among modes, wherein the FMF amplifier obtains a gain by amplifying an optical signal with the optical pump.

Abstract: An optical transmitting apparatus based on multicarrier differential phase shift keying. The optical transmitting may include a multicarrier generator to output two or more optical signals, each of which has a different wavelength; two or more optical modulators to receive the two or more optical signals, respectively, which have been output from the multicarrier generator, wherein each of the two or more optical modulators modulates phases of the two or more received optical signals by electrical signals that are applied in pairs.

Abstract: An optical transmitter including an optical modulator comprising a first modulator and a second modulator connected in parallel to each other in the form of a Mach-Zehnder interferometer, and a phase shifter connected to the second modulator in series, a high-speed generator configured to generate a single carrier signal or multi-carrier signals and apply the generated single carrier signal or multi-carrier signals to the optical modulator, and an output stabilizer configured to stabilize a final output optical signal of the optical modulator by controlling a bias of each of the first modulator, the second modulator and the phase shifter.

Abstract: Disclosed is an optical signal transmitting apparatus including: an optical carrier generator configured to generate a plurality of optical carriers and outputs the optical carriers to optical modulators corresponding to the optical carriers, respectively; a plurality of optical modulators configured to modulate the optical carriers, respectively, according to an input signal; and an optical combiner configured to couple a plurality of optical signals from the plurality of optical modulators.

Abstract: An optical transmission apparatus includes: a transmission light source configured to generate single-mode light of a specific wavelength; a power coupler configured to split the light generated by the transmission light source into a plurality of light sections; at least one modulator configured to modulate an electrical signal carrying different data into at least one optical signal using the light section from the power coupler; and a mode multiplexer configured to convert the modulated optical signal into a different mode, and to transmit the mode-converted optical signal to a fiber.