Abstract: Disclosed is a polarized light generating device based on an optical waveguide, which includes first to fourth input optical waveguides, respectively, for receiving input light from an outside, first to fifth optical splitters configured to receive at least one light and output the received at least one light as at least one light, and an optical converter configured to receive at least one light from the fifth optical splitter and convert the received light to generate polarized light. The polarized light generating device receives the input light through one of the first to fourth input optical waveguides, and generates a first polarized light, a second polarized light, a third polarized light, and a fourth polarized light. The first to fourth polarized lights belong to elements of two arbitrary two-dimensional mutually unbiased basis sets.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Provided are a single-photon source device and a single-photon source system including same. The single-photon source device includes a substrate, a straight waveguide extending in a first direction on the substrate, a first coupling layer which is provided on the straight waveguide and has a first point defect, at least one first electrode which is adjacent to the first point defect and provided on the first coupling layer, a ring waveguide which is adjacent to the straight waveguide and provided on the substrate, and at least one second electrode provided on the ring waveguide.

Abstract: Disclosed are a quantum light source and an optical communication apparatus including the same. The quantum light source device includes a vertical reflection layer disposed on a substrate, a lower electrode layer disposed on the vertical reflection layer, a horizontal reflection layer disposed on the lower electrode layer, a quantum light source disposed in the horizontal reflection layer, and an upper electrode layer disposed on the horizontal reflection layer.

Abstract: 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.

Abstract: Provided are a single-photon source device and a single-photon source system including same. The single-photon source device includes a substrate, a straight waveguide extending in a first direction on the substrate, a first coupling layer which is provided on the straight waveguide and has a first point defect, at least one first electrode which is adjacent to the first point defect and provided on the first coupling layer, a ring waveguide which is adjacent to the straight waveguide and provided on the substrate, and at least one second electrode provided on the ring waveguide.

Abstract: 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.

Abstract: Provided is a light modulation device includes a substrate, a lower clad layer disposed on the substrate, a core layer disposed on the lower clad layer to extend in a first direction which is parallel to a top surface of the substrate, and an upper clad layer covering the core on the lower clad layer. The core layer includes a waveguide layer extending in the first direction; and photonic crystal structures disposed in the waveguide layer and periodically arranged along the first direction.

Abstract: 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.

Abstract: Disclosed are a quantum light source and an optical communication apparatus including the same. The quantum light source device includes a vertical reflection layer disposed on a substrate, a lower electrode layer disposed on the vertical reflection layer, a horizontal reflection layer disposed on the lower electrode layer, a quantum light source disposed in the horizontal reflection layer, and an upper electrode layer disposed on the horizontal reflection layer.

Abstract: 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.

Abstract: Provided is an apparatus configured to split light into a plurality of polarizations, the apparatus including an input waveguide configured to receive the light, a first interferometer configured to split the light into a first polarization and a second polarization, and a second interferometer configured to split the light into a third polarization and a fourth polarization, wherein the first interferometer and the second interferometer are connected in parallel, the first interferometer comprises a first output waveguide configured to output the first polarization, and a second output waveguide configured to output the second polarization, and the second interferometer comprises a third output waveguide configured to output the third polarization, and a fourth output waveguide configured to output the fourth polarization.

Abstract: Provided is an electro-optic modulating device. The electro-optic modulating device includes an optical waveguide with a vertical structure and sidewalls of the vertical structure are used to configure a junction.

Abstract: Provided is a ring resonator including first and second waveguides disposed spaced apart from each other, on a substrate, and at least one channel including at least one ring waveguide arranged in a row between the first and second waveguides. The first and second waveguides and the ring waveguide may be formed of silicon, a width of the ring waveguide may range from 0.7 ?m to 1.5 ?m, a height of the ring waveguide may range from 150 nm to 300 nm, and a space between the first and second waveguides and the ring waveguide most adjacent thereto may range from 250 nm to 1 mm.

Abstract: Provided are a method of forming a waveguide facet and a photonics device using the method. The method includes forming at least one optical device die including waveguides on a substrate, forming at least one trench in a lower surface of the substrate, and cleaving the substrate to form facets of the waveguides over the trench. The trench is formed along a direction crossing the waveguides under the waveguides.

Abstract: Provided is an electro-optic modulating device. The electro-optic modulating device includes an optical waveguide with a vertical structure and sidewalls of the vertical structure are used to configure a junction.

Abstract: Provided are an optical device and a method of fabricating the same. The optical device includes: a substrate; and a ring resonator on the substrate. The ring resonator includes: a cladding layer including a lower cladding layer and an upper cladding layer on the substrate; a core including a plurality of rings between the lower cladding layer and the upper cladding layer; and an embeded layer interposed between the core and the cladding layer and having a refractive index less than that of the core and more than that of the cladding layer.

Abstract: Provided are a method of fabricating a semiconductor device unconstrained by optical limit and an apparatus of fabricating the semiconductor device. The method includes: forming an etch target layer on a substrate; forming a hard mask layer on the etch target layer; forming first mask patterns on the hard mask layer; forming first spacers on sidewalls of the first mask patterns; forming hard mask patterns having an opening by using the first mask patterns and the first spacers as a mask to etch the hard mask layer; aligning second mask patterns on the hard mask patterns to fill the opening; forming second spacers on sidewalls of the second mask patterns; forming fine mask patterns by using the second mask patterns and the second spacers as a mask to etch the hard mask patterns; and forming fine patterns by using the fine mask patterns as a mask to etch the etch target layer.