Abstract: A method of detecting a biomolecule, a computing device performing the method, and a biomolecule detection system therefor are provided. The method includes receiving a terahertz signal that passed deionized water or reference material, receiving a terahertz signal that passed a target including a predetermined biomolecule, extracting a digital modulation characteristic for the received terahertz signal that passed the deionized water and the received terahertz signal that passed the target, and detecting the predetermined biomolecule included in the target by analyzing the extracted digital modulation characteristic, wherein the received terahertz signal that passed the deionized water and the received terahertz signal that passed the target are generated using a digitally modulated optical signal based on a transmission speed determined based on kinematics of the predetermined biomolecule.

Abstract: Provided are an apparatus and method of generating a terahertz (THz) signal using a directly-modulated laser. An apparatus of generating a THz signal includes a first directly-modulated laser configured to output a local oscillator (LO) signal, a second directly-modulated laser configured to receive a baseband signal used as data and optically modulate the baseband signal, a band-pass filter configured to filter a spectral component of the baseband signal optically modulated and outputted through the second directly-modulated laser by using a specific frequency bandwidth, a coupler configured to couple the baseband signal filtered through the band-pass filter and the LO signal to each other, and a uni-travelling-carrier photodiode (UTC-PD) configured to generate a THz signal by beating the baseband signal and the LO signal coupled to each other.

Abstract: An apparatus and method for maintaining a wavelength interval of light sources are disclosed. The apparatus for maintaining a wavelength interval of light sources includes: a plurality of light sources configured to output light having different wavelengths and having a certain wavelength interval; a light reception unit configured to receive an optical signal in which at least some of the output light of each of the plurality of light sources is combined and output an electrical signal including a frequency component corresponding to the certain wavelength interval; and a controller configured to detect the frequency component corresponding to the certain wavelength interval from the electrical signal and control a wavelength of each of the plurality of light sources to maintain the certain wavelength interval based on the detected frequency component.

Abstract: Disclosed is a method and apparatus for phase error compensation having tolerance to a cyclic slip. The method includes determining first phase error candidates based on symbol phases of a first block of a received signal, determining an initial estimation error according to the first phase error candidates, determining second phase error candidates based on symbol phases of a second block of the received signal, determining a final estimation error according to the initial estimation error and the second phase error candidates, and compensating for a phase of the received signal according to the final estimation error.

Abstract: Provided are a Kramers—Kronig (KK) reception-based terahertz (THz) signal reception apparatus and a method for compensating a frequency offset using the same. A method of compensating for a frequency offset performed by a THz signal reception apparatus includes receiving, from a THz signal transmission apparatus, a THz signal including carrier signals corresponding to three different frequency bands, extracting, from the received THz signal, a reference carrier included in the THz signal or a sampling clock generated in a process of generating a data signal, and compensating for a frequency offset generated in a process of transmitting the THz signal by using the extracted reference carrier or sampling clock.

Abstract: Provided are an apparatus and method of generating a terahertz (THz) signal using a directly-modulated laser. An apparatus of generating a THz signal includes a first directly-modulated laser configured to output a local oscillator (LO) signal, a second directly-modulated laser configured to receive a baseband signal used as data and optically modulate the baseband signal, a band-pass filter configured to filter a spectral component of the baseband signal optically modulated and outputted through the second directly-modulated laser by using a specific frequency bandwidth, a coupler configured to couple the baseband signal filtered through the band-pass filter and the LO signal to each other, and a uni-travelling-carrier photodiode (UTC-PD) configured to generate a THz signal by beating the baseband signal and the LO signal coupled to each other.

Abstract: Disclosed is a method and apparatus for phase error compensation having tolerance to a cyclic slip. The method includes determining first phase error candidates based on symbol phases of a first block of a received signal, determining an initial estimation error according to the first phase error candidates, determining second phase error candidates based on symbol phases of a second block of the received signal, determining a final estimation error according to the initial estimation error and the second phase error candidates, and compensating for a phase of the received signal according to the final estimation error.

Abstract: Disclosed is a radio-frequency-over-fiber (RFoF) transmission method using a directly modulated laser (DML). The RFoF transmission method to be performed by a head end includes combining a radio frequency (RF) carrier signal and a data signal having a lower frequency band than the RF carrier signal through an RF coupler, modulating the combined RF carrier signal and the combined data signal using a frequency response characteristic of a DML, and outputting an optical signal in which, of RF carrier signals and data signals being generated in a laterally symmetrical form based on an optical carrier frequency through the modulating, an RF carrier signal is suppressed.

Abstract: Provided is an optical transmitting and receiving system. The optical transmitting and receiving system may include: a Main Hub Unit (MHU) configured to perform wavelength division multiplexing on a plurality of downlink signals using a plurality of wavelengths and transmit the multiplexed downlink signal through a first optical cable; a first Remote Optical Unit (ROU) configured to perform demultiplexing on the multiplexed downlink signal received from the MHU and output a part of the plurality of downlink signals; and a second ROU configured to perform demultiplexing on the multiplexed downlink signal and output other part of the plurality of downlink signals.

Abstract: A wavelength-division multiplexing optical communication system and a method for measuring optical performance of an output signal for the system. The optical communication system includes: a service-provider device; a local node; and a plurality of subscriber devices. The service-provider device includes: a plurality of first optical transceivers; a first optical multiplexer/demultiplexer (OD/OM) connected to the plurality of first optical transceivers; and a seed-light source providing seed light. Each subscriber device includes a second optical transceiver. The local node connects the service-provider device and the plurality of subscriber devices to each other using aDWDM link comprising: a second multiplexer/demultiplexer (OD/OM); and a single-mode optical fiber for transmission. Here, the optical intensity of an output signal of the second optical transceiver is determined by compensating for the value of the loss caused when the output signal passes through the second OD/OM of the local node.

Abstract: A wavelength-division multiplexing optical communication system and a method for measuring optical performance of an output signal for the system. The optical communication system includes: a service-provider device; a local node; and a plurality of subscriber devices. The service-provider device includes: a plurality of first optical transceivers; a first optical multiplexer/demultiplexer (OD/OM) connected to the plurality of first optical transceivers; and a seed-light source providing seed light. Each subscriber device includes a second optical transceiver. The local node connects the service-provider device and the plurality of subscriber devices to each other using a DWDM link comprising: a second multiplexer/demultiplexer (OD/OM); and a single-mode optical fiber for transmission. Here, the optical intensity of an output signal of the second optical transceiver is determined by compensating for the value of the loss caused when the output signal passes through the second OD/OM of the local node.

Abstract: A wavelength-division multiplexing optical communication system and a method for measuring optical performance of an output signal for the system. The optical communication system includes: a service-provider device; a local node; and a plurality of subscriber devices. The service-provider device includes: a plurality of first optical transceivers; a first optical multiplexer/demultiplexer (OD/OM) connected to the plurality of first optical transceivers; and a seed-light source providing seed light. Each subscriber device includes a second optical transceiver. The local node connects the service-provider device and the plurality of subscriber devices to each other using a DWDM link comprising: a second multiplexer/demultiplexer (OD/OM); and a single-mode optical fiber for transmission. Here, the optical intensity of an output signal of the second optical transceiver is determined by compensating for the value of the loss caused when the output signal passes through the second OD/OM of the local node.