Abstract: Provided are a method and an apparatus for optimizing the performance of an optical transceiver, and the gist is as follows: receiving an optical input and converting the optical input into electrical signals; receiving a performance value and a reference clock of the electrical signals from a DSP part; generating a plurality of clocks by using the reference clock; determining ADC sampling timings of a plurality of ADCs on the basis of phases of the plurality of clocks applied to the plurality of ADCs; and compensating, on the basis of the determined ADC sampling timings, for differences in physical length between output signals of the plurality of ADCs.

Abstract: Provided are an apparatus and method for parallel Reed-Solomon (RS) encoding. A parallel RS encoding apparatus includes a coefficient generator configured to calculate a parity symbol matrix and group coefficients of each row or each column of the parity symbol matrix to correspond to the number of parallel paths, a data delayer configured to delay a parallel input information symbol block including symbols of the number of parallel paths so that calculation of a parity symbol is processed in order, a parity symbol calculator configured to calculate, based on the grouped coefficients outputted from the coefficient generator and the parallel input information symbol block delayed by the data delayer, the parity symbol, and a parallel outputter configured to output a codeword generated based on the parity symbol outputted from the parity symbol calculator and the parallel input information symbol block delayed by the data delayer.

Abstract: A method of generating a terahertz wave and apparatuses performing the method are disclosed. According to an example embodiment, a method of generating a terahertz wave includes outputting a laser comb by modulating a laser output from a laser source based on a linearly modulated frequency of an output that is output from a frequency source, and generating a terahertz wave based on a first comb line and a second comb line selected from the laser comb.

Abstract: An optical transceiver and a method of setting a wavelength of the optical transceiver. The optical transceiver may include a thermoelectric cooler (TEC) configured to maintain a constant operating temperature of a transmitter optical sub-assembly (TOSA) of the optical transceiver based on an installation environment of the optical transceiver, a plurality of laser diodes arranged on the top of the TEC and configured to output optical signals having different wavelengths, an optical multiplexer configured to multiplex the optical signals having different wavelengths, output through the plurality of laser diodes, and a wavelength controller configured to control the wavelengths of the optical signals output through the plurality of laser diodes such that optical outputs of the optical signals having different wavelengths, detected through the optical multiplexer, are maximized, wherein the wavelength controller may be individually arranged in one region of each of the plurality of laser diodes.

Abstract: A method of generating a terahertz wave and apparatuses performing the method are disclosed. According to an example embodiment, a method of generating a terahertz wave includes outputting a laser comb by modulating a laser output from a laser source based on a linearly modulated frequency of an output that is output from a frequency source, and generating a terahertz wave based on a first comb line and a second comb line selected from the laser comb.

Abstract: An optical connection apparatus includes a position fixing portion configured to fix optical circuits each having a different end portion, while interposing a connection member that is optically imprintable between the optical circuits, and an optical-imprinting portion configured to emit light to the connection member to form a three-dimensional (3D) optical waveguide in the connection member that connects the optical circuits to each other.

Abstract: A wireless signal transmitter and a wireless signal receiver are provided. The wireless signal transmitter includes an optical signal generation region that generates excitation light by beating two optical signals that have different wavelengths and that are output through different laser diodes, and a wireless signal generation region that modulates the excitation light output from the optical signal generation region into a wireless signal with a carrier frequency of a terahertz band, using a photomixer. The optical signal generation region and the wireless signal generation region may be connected by a multimode optical fiber to reduce a nonlinear effect occurring in an optical fiber. Also, the wireless signal receiver includes a signal processor, for example, an equalizer, for compensating for a modal dispersion, and may compensate for a modal dispersion caused by the multimode optical fiber used in the wireless signal transmitter.

Abstract: An optical transmission method for processing a signal based on direct detection includes setting, by an equalizer, an adaptive equalization coefficient by performing an equalization process during a training symbol field section in a frame of a received signal, performing, by a channel estimator, channel estimation to perform an equalization process of a soft output maximum likelihood sequence equalizer (MLSE) during the training symbol field section, driving the soft output MLSE, and compensating for, by the soft output MLSE, distortion of the received signal during a data symbol field section in the frame on the basis of the adaptive equalization coefficient and an estimated result value of a channel, and recovering, by an error corrector which allows soft-decision processing to be performed, the received signal by performing error correction on the received signal in which the distortion is compensated for.

Abstract: An optical transmission method for processing a signal based on direct detection includes setting, by an equalizer, an adaptive equalization coefficient by performing an equalization process during a training symbol field section in a frame of a received signal, performing, by a channel estimator, channel estimation to perform an equalization process of a soft output maximum likelihood sequence equalizer (MLSE) during the training symbol field section, driving the soft output MLSE, and compensating for, by the soft output MLSE, distortion of the received signal during a data symbol field section in the frame on the basis of the adaptive equalization coefficient and an estimated result value of a channel, and recovering, by an error corrector which allows soft-decision processing to be performed, the received signal by performing error correction on the received signal in which the distortion is compensated for.

Abstract: An optical connection apparatus includes a position fixing portion configured to fix optical circuits each having a different end portion, while interposing a connection member that is optically imprintable between the optical circuits, and an optical-imprinting portion configured to emit light to the connection member to form a three-dimensional (3D) optical waveguide in the connection member that connects the optical circuits to each other.

Abstract: An optical signal transmission apparatus generates a multi-level optical signal from a multi-level electric signal. The optical signal transmission apparatus detects, based on a supervisory signal generated from an optical signal, an electric-to-optical (E/O) conversion characteristic of an E/O converter configured to convert an electric signal into an optical signal. For example, when the E/O converter generates a multi-level optical signal from a multi-level electric signal based on a bias signal, the optical signal transmission apparatus determines a correspondence relationship between the bias signal and the optical signal. The optical signal transmission apparatus adjusts a use range of intensities of the bias signal based on the determined correspondence relationship so that the E/O converter may linearly operate.

Abstract: A method and apparatus for compensation of a chromatic dispersion through an optical compensation and an electronical compensation in optical communication. An optical communication method receives an optical signal, estimates a first transmission length based on a null component included in a frequency spectrum of the optical signal, optically compensates for a chromatic dispersion of the optical signal based on the first transmission length, estimates a second transmission length based on a null component included in a frequency spectrum of the compensated optical signal, and electronically compensates for a residual chromatic dispersion of the compensated optical signal based on the second transmission length.

Abstract: A method and apparatus for compensation of a chromatic dispersion through an optical compensation and an electronical compensation in optical communication. An optical communication method receives an optical signal, estimates a first transmission length based on a null component included in a frequency spectrum of the optical signal, optically compensates for a chromatic dispersion of the optical signal based on the first transmission length, estimates a second transmission length based on a null component included in a frequency spectrum of the compensated optical signal, and electronically compensates for a residual chromatic dispersion of the compensated optical signal based on the second transmission length.

Abstract: An optical receiver and a method of controlling the optical receiver. The method may include setting, by a controller, a dispersion value of a dispersion compensator to compensate for a dispersion of an optical signal received through an optical fiber, compensating, by the dispersion compensator, for the dispersion of the optical signal based on the set dispersion value, performing, by the controller, an error correction with respect to the optical signal of which the dispersion is compensated and verifying a number of bit errors, and resetting, by the controller, the dispersion value of the dispersion compensator based on the verified number of bit errors.

Abstract: An optical signal transmission apparatus generates a multi-level optical signal from a multi-level electric signal. The optical signal transmission apparatus detects, based on a supervisory signal generated from an optical signal, an electric-to-optical (E/O) conversion characteristic of an E/O converter configured to convert an electric signal into an optical signal. For example, when the E/O converter generates a multi-level optical signal from a multi-level electric signal based on a bias signal, the optical signal transmission apparatus determines a correspondence relationship between the bias signal and the optical signal. The optical signal transmission apparatus adjusts a use range of intensities of the bias signal based on the determined correspondence relationship so that the E/O converter may linearly operate.

Abstract: A Mode Division Multiplexed Passive Optical Network (MDM-PON) apparatus includes: a non-mode selective multiplexer which includes a first end where three or more single-mode optical fibers are spaced apart from each other by a predetermined distance, and a second end where cores of the three or more single-mode optical fibers are tapered such that a gap between the three or more single-mode optical fibers is narrower than the predetermined distance while the three or more single-mode optical fibers are spaced apart from each other by an equal distance; an optical line terminal (OLT) which is connected to the second end through a few-mode fiber, and transmits a downstream optical signal; and three or more optical network units (ONUs) which is connected to the first end through the three or more single-mode optical fibers, and transmits upstream optical signals.

Abstract: A Mode Division Multiplexed Passive Optical Network (MDM-PON) apparatus includes: a non-mode selective multiplexer which includes a first end where three or more single-mode optical fibers are spaced apart from each other by a predetermined distance, and a second end where cores of the three or more single-mode optical fibers are tapered such that a gap between the three or more single-mode optical fibers is narrower than the predetermined distance while the three or more single-mode optical fibers are spaced apart from each other by an equal distance; an optical line terminal (OLT) which is connected to the second end through a few-mode fiber, and transmits a downstream optical signal; and three or more optical network units (ONUs) which is connected to the first end through the three or more single-mode optical fibers, and transmits upstream optical signals.

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: 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.