Electronics and Telecommunications Research Institute

Sun Hyok Chang

Hwan Seok Chung

Hyun Jae Lee

Hee Sang Chung

Hun Sik Kang

Kwangjoon Kim

Won Kyoung Lee

In Ki Hwang

Sang Rok Moon

Joon Ki Lee

Sang Soo Lee

Moo Jung Chu

Seung-Woo Lee

Seung Woo Lee

Han Hyub Lee

Sae-Kyoung Kang

Heuk Park

Joon Young Huh

Kwang Joon Kim

Jie Hyun Lee

Jin Soo Han

Chan Gyo Han

Dong Han Lee

Yong Bae Lee

Ji Sung Jung

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.

Method and apparatus for optimizing performance of optical transceiver

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.

Method of generating terahertz wave and apparatuses performing the same

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.

Optical connection apparatus and optical connection method using the same

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.

Optical transmission apparatus and method for processing signal based on direct detection

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.

Apparatus and method for equalization and compensation of chromatic dispersion in optical transmission

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.

Optical signal transmission apparatus for generating multi-level optical signal and method performed by the same

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.

Mode division multiplexed passive optical network (MDM-PON) apparatus, and transmission and reception method using the same

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.

Polarization control device and method

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.

Multicarrier based optical signal transmitting apparatus and optical signal receiving apparatus

Provided is a coherent optical receiving apparatus and an optical signal processing method. The coherent optical receiving apparatus may include an optical hybrid unit to generate an optical signal by combining a first optical signal inputted from an optical transmitting apparatus and a second optical signal inputted from a local oscillator, a polarization demuxer to demultiplex the optical signal outputted from the optical hybridizing unit, a frequency offset compensator to estimate a frequency offset of at least one of even-numbered samples and odd-numbered samples, and to compensate for a frequency offset of the even-numbered samples and a frequency offset of the odd-numbered samples using the at least one estimated frequency offset, and a carver distortion compensator to compensate for phase distortions of the samples for which the compensation for the frequency offset is performed, the phase distortions being generated by the optical transmitting apparatus.

Coherent optical receiving apparatus and optical signal processing method

An optical node capable of supporting a mesh-type optical network is provided. The node includes: N ROADMs, which separate specific wavelength channels from a multiple wavelength channel optical signal that is input from any node constituting the optical network, allows the rest of the wavelength channels to be passed, and combine another added wavelength channel with the passed wavelength channel to allow the combined wavelength channel to be passed; an N&#xd7;1 optical switch which selects the specific wavelength channel separated from one of the N ROADMs and inputs the specific wavelength channel into an optical transceiver and selects one of the N ROADMs and connects a wavelength channel that is output from the optical transceiver to the selected ROADM; and an electrical cross connect switch which drops a part of electrical signal bandwidth of the specific wavelength channels separated by the ROADM, which is converted into the electrical signals in the optical transceiver, toward an external client and combines the rest of the electrical signal bandwidth with a electrical signal added by the external client to form an electrical signal bandwidth of a wavelength channel and output the electrical signal to the optical transceiver. Accordingly, optical fiber inputs and outputs in various directions can be supported, and the number of WDM transceivers used for each node is remarkably reduced, thereby improving efficiency and economical efficiency of a network.

Optical node for mesh-type WDM optical network

Provided are a photonic cross-connector system, a wavelength division multiplexing (WDM) system using the photonic cross-connector system, and an optical communication network based on the WDM system. The photonic cross-connector system includes: an optical coupler branching an input optical signal into a plurality of paths; a wavelength selective switch (WSS) extracting at least one wavelength signal from the input optical signal and outputting the extracted wavelength signal to at least one port; a WDM multi-casting apparatus simultaneously copying and reproducing the input optical signal into different wavelengths and changing modulation methods of the input optical signal into different types of modulation methods; an optical transmitter and/or receiver branching and coupling the input optical signal; and a control system controlling the optical coupler, the WSS, the WDM multicasting apparatus, and the optical transmitter and/or receiver.

Photonic cross-connector system, WDM system using the same photonic cross-connector, and optical communication network based on the same WDM system

Provided is a hybrid optical amplifier using a gain-clamped semiconductor optical amplifier enabling Raman amplification. The hybrid optical amplifier comprises a spool of optical fiber used as transmission line in the optical communication, a GCSOA amplifying optical signal input via the optical fiber and generating a self-oscillation laser beam for gain-clamping through the gain medium, and a backward pumping Raman optical amplifier inducing Raman amplification by emitting the self-oscillation laser beam generated by the GCSOA into the optical fiber. Therefore, the Raman amplification can be obtained with a relatively simple structure using the GCSOA.

Hybrid optical amplifier using gain-clamped semiconductor optical amplifier enabling raman amplification

Provided are a Raman amplifier and a Raman pumping method. A light source unit outputs a pumping light having a wavelength that periodically changes. A light intensity control unit varies a light intensity of the pumping light using the pumping light to improve the gain flatness of a Raman gain. A control unit directs the light intensity control unit to control the light intensity of the pumping light in synchronization with changes in the wavelength of the pumping light.

Raman amplifier and raman pumping method

A dispersion compensating fiber (DCF), which is an amplification medium of an S-band discrete Raman amplifier (RA), has a trapezoid core, an inner cladding surrounding the trapezoid core; and an outer cladding surrounding the inner cladding. A ring is disposed between the inner cladding and the outer cladding. The refractive index plotted across the diameter of the trapezoid core as a function of distance is substantially trapezoidal in shape. The difference in refractive index between the trapezoid core and the outer cladding is 1.2 to 1.6%; between the inner cladding and the outer cladding is 0.4 to 0.8%; and between the ring and the outer cladding is 0.2 to 0.6%. The thickness of the ring is 0.8 to 1.2 times the radius of the trapezoid core, and the thickness of the inner cladding is 1 to 3 times the radius of the trapezoid core.

Growing community of inventors

Daejeon, South Korea

Sun Hyok Chang