Electronics and Telecommunications Research Institute

Chun Ju Youn

Joong-Seon Choe

Eun Soo Nam

Yong-Hwan Kwon

Jong-Hoi Kim

Kwang-Seong Choi

Duk Jun Kim

Minchul Kim

Byung-Seok Choi

Kap-Joong Kim

Kyongchun Lim

Jong Hoi Kim

Young-Ho Ko

Joong Seon Choe

Tae Gon Noh

Taehyoung Zyung

Young Tak Han

Byung Seok Choi

Seo Young Lee

Jong Cheol Hong

Byung-seok Choi

Hyun Do Jung

Kyoungwoo Heo

Kap Joong Kim

Ju Hee Baek

Heasin Ko

Heon Oh Kim

Kyoungchun Lim

A quantum key distribution system using an RFI (reference frame independent) QKD (quantum key distribution) protocol includes a quantum channel transmitter that generates a first quantum signal including quantum information and provides the first quantum signal to an external device through a quantum channel, a first public channel transceiver that generates an optical signal including first additional information related to a QKD operation, and transmits and receives the optical signal through a public channel, a second public channel transceiver that receives the optical signal through the public channel and generates a measurement result by measuring a circular polarization component of the optical signal, and a quantum channel receiver that receives the first quantum signal through the quantum channel, generates a second quantum signal by correcting a polarization distortion of the first quantum signal based on the measurement result, and demodulates the quantum information from the second quantum signal.

Quantum key distribution system and operation method thereof

Provided are a beam tracking module, a free-space quantum communication device, and a free-space optical communication device. The beam tracking module for free-space quantum communication includes a controller configured to determine a divergence angle of a reference beam on the basis of divergence angle control data, a beam path control optical part configured to output the reference beam, and a beam transmitter configured to adjust the divergence angle through the beam path control optical part so that the reference beam having the determined divergence angle is output.

Beam tracking module, free-space quantum communication device, and free-space optical communication device

An optical alignment device according to an embodiment of the inventive concept includes an optical alignment plate having a first hole and at least one second hole, in which the first hole and the second hole pass through the optical alignment plate, and an optical detection element disposed on the optical alignment plate. Here, the optical detection element includes a substrate having a first surface and a second surface, which face each other, a lens disposed on the first surface, and an optical sensor disposed on the second surface, and the optical detection element vertically overlaps the first hole and the second hole. The lens is exposed to the outside by the first hole, and the second hole is connected with a vacuum suction unit to fix the optical detection element to the optical alignment plate.

Optical alignment device

Provided is a polarization decomposition device. The polarization decomposition device includes a polarization beam splitter configured to split an optical signal into a first polarized light having a first polarization direction and a second polarized light having a second polarization direction different from the first polarized light, a phase shifter configured to delay a phase of the first polarized light, a polarization rotator configured to rotate the second polarized light so that the polarization direction of the second polarized light is changed, and an interference beam splitter configured to allow the first polarized light in which the phase is delayed and the second polarized light in which the polarization direction is rotated to interfere with each other and split them into a third polarized light and a fourth polarized light.

Polarization decomposition device

Disclosed is a quantum key distribution system using an RFI (reference frame independent) QKD (quantum key distribution) protocol, which includes a first signal processing circuit that generates transmission basis information and transmission bit information, a quantum channel transmitter that generates a single photon or coherent light, and modulates the single photon or the coherent light based on the transmission basis information and the transmission bit information to generate a quantum signal, a quantum channel receiver that receives the quantum signal through a quantum channel and detects reception bit information from the quantum signal based on reception basis information, and a second signal processing circuit that generates the reception basis information, transmits the reception basis information to the first signal processing circuit through a public channel, and receives the transmission basis information from the first signal processing circuit through the public channel.

Disclosed are a quantum information transmitter, a quantum communication system including the same, and an operating method of the quantum information transmitter. The quantum information transmitter includes a light source driver, a light source, and a light modulator. The light source driver generates a first light source driving signal having a first level and a second light source driving signal having a second level. The light source generates a first light signal having a first average number of photons in response to the first light source driving signal, and generates a second light signal having a second average number of photons in response to the second light source driving signal. The optical modulator modulates the first light signal to generate a target signal, and modulates the second light signal to generate a decoy signal.

Quantum information transmitter, quantum communication system including the same, and operating method of quantum information transmitter

There is provided a receiver optical module including a photodetector having a plurality of channels, a capacitor disposing block formed on an upper portion of the photodetector, a plurality of capacitors formed on the capacitor disposing block, and an electrical wiring configured to connect the plurality of capacitors to electrodes of a plurality of channels of the photodetector, wherein the plurality of capacitors are formed on the capacitor disposing block such that distance between the capacitors and the electrodes of the corresponding channels are the same. Distortion and loss of signal characteristics of high frequency can be reduced and quality of a signal can be enhanced.

Receiver optical module

A multiple output quantum random number generator coherently measures an optical source noise and outputs a random number sequence based on the independent and coherent measurement of optical source noise. Therefore, it is possible to output a random number sequence at a high speed and to perform multiple outputs.

Multiple output quantum random number generator

Disclosed are a method and an apparatus for transmitting and receiving coherent optical OFDM. The apparatus includes: a transmitted OFDM digital signal processing unit outputting an in-phase (I) component digital signal and a quadrature phase (Q) component digital signal; a digital-analog converter converting the in-phase (I)-component digital signal and the quadrature-phase (Q)-component digital signal into an in-phase (I)-component analog signal and a quadrature-phase (Q)-component analog signal, respectively; an adder adding an additional pilot tone signal to each of the in-phase (I)-component analog signal and the quadrature-phase (Q)-component analog signal outputted from the digital-analog converter; and an optical I/Q modulator up-converting the in-phase (I)-component analog signal added with the additional pilot tone signal and the quadrature-phase (Q)-component analog signal added with the additional pilot tone signal to an optical domain to output a coherent optical OFDM signal including the additional pilot tone signal.

Method and apparatus for transmitting and receiving coherent optical OFDM

Provided is an apparatus and method for measuring IQ imbalance, and in particular, is an apparatus and method for measuring IQ imbalance for an optical receiver. The apparatus for measuring IQ imbalance for an optical receiver includes a light generating unit generating optical and reference signals to provide the optical and reference signals to an optical receiver, a graph creating unit creating a Lissajous figure by using an in-phase (I) signal and a quadrature-phase (Q) signal output from the optical receiver in response to the optical and reference signals, and a calculating unit calculating IQ imbalance for the optical receiver with reference to the Lissajous figure.

Apparatus and method for measuring IQ imbalance for optical receiver

Provided is a method of measuring signal transmission time difference of a measuring device. The measuring device according to embodiments, by measuring a skew on two optical paths through signal delays of sufficient sizes for skew measurement on the optical paths, even a skew having a minute size can be measured within a measurable range.

Measuring device and method of measuring signal transmission time difference thereof

An apparatus for measuring performance of a coherent optical receiver includes a beam splitter splitting light into first and second paths, a first optical modulator modulating the first path light, a variable optical attenuator controlling an optical power of the first optical modulator, a first polarization controller transmitting a signal controlling polarization of an output of the variable optical attenuator to the coherent optical receiver, a second optical modulator modulating the second path light, a variable optical delay line delaying time of an output of the second optical modulator, a second polarization controller transmitting a signal controlling polarization of an output of the variable optical delay line to the coherent optical receiver, a network analyzer measuring performance of the coherent optical receiver and controlling the optical modulators, and a controller transmitting a control signal to the optical modulators.

Apparatus for measuring performance of coherent optical receiver

Provided is a polarization division multiplexed optical OFDM transmitter. The polarization division multiplexed optical OFDM transmitter includes a data demultiplexer, a training symbol generation unit and an optical up-converter and polarization division multiplexing unit. The data demultiplexer divides a transmission signal into a plurality of groups. The training symbol generation unit allocates a plurality of training symbols for each OFDM data which is included in the respective multiplexed groups, and allocates repetitive data in a time domain for the respective training symbols for data of 0 to periodically appear for the respective training symbols in a frequency domain. The optical up-converter and polarization division multiplexing unit performs optical frequency band conversion and polarization division multiplexing on an output of the training symbol generation unit to output a polarization division multiplexed optical OFDM signal corresponding to a plurality of polarization components.

Polarization division multiplexed optical orthogonal frequency division multiplexing transmitter and receiver

Provided is an optical OFDM receiver. The optical OFDM receiver receives an optical signal dependent on the nonlinearity of a transmitter. The optical OFDM receives includes an optical down converter, a nonlinearity compensator, and an OFDM demodulator. The optical down converter converts the optical signal into an electrical signal. The nonlinearity compensator filters the electrical signal, for compensating distortion which is added to the optical signal when the transmitter performs optical modulation. The OFDM demodulator demodulates the distortion-compensated electrical signal in an OFDM scheme.

Optical orthogonal frequency division multiplexing receiver and optical signal receiving method thereof

Provided are an apparatus for receiving a quantum cryptographic key and an apparatus for transmitting and receiving a quantum cryptographic key at high speed without polarization drift of an optical pulse signal and phase drift of an interferometer. The apparatus for receiving a quantum key includes: a polarization-insensitive optical phase modulator parts for receiving an optical pulse signal, and modulating and outputting a phase of the optical pulse signal without being affected by the polarization state of the optical pulse signal; an asymmetric Mach-Zehnder interferometer for causing interference in and outputting the optical pulse signal received from the polarization-insensitive optical phase modulator parts; and a photon detectors for detecting the optical pulse signal received from the asymmetric Mach-Zehnder interferometer. According to the apparatuses, it is possible to perform quantum cryptography communication at high speed without being affected by polarization drift of an optical pulse signal and phase drift of an interferometer.

Growing community of inventors

Daejeon, South Korea

Chun Ju Youn