Abstract: There is disclosed a visible light communication technology capable of intuitively recognizing a transmission speed, an alignment state, a communication state, or a transmission rate. A visible light communication apparatus according to an embodiment of the present invention includes: a light source selecting unit selecting at least one light source from among a plurality of light sources generating lights having different wavelengths by considering intuitive information distinguished depending on a wavelength in a visible light band; and a visible light communication unit performing visible light communication by at least one selected light source to allow the intuitive information to be recognized by a color corresponding to at least one selected light source. Accordingly, a user using the visible light communication can intuitively know an optimal communication state or transmission speed.

Abstract: A visible light communication apparatus of the present invention includes: a target signal receiver filtering only a signal having a target wavelength from a visible light received signal received from a transmitting terminal; a signal generator judging a reception quality of the visible light received signal by using characteristics of the signal having the target wavelength and generating a visible signal by using at least one light source having a wavelength different from the target wavelength in accordance with the reception quality; and an optical signal transmitter transmitting the signal having the target wavelength for transmitting data together with the visible signal and changing a light emitting color of a visible light transmitted signal.

Abstract: Provided are a time-division data multiplexing/demultiplexing system and method capable of preventing errors in processing data signals which occur due to a phase difference between data signals and a multiplexing reference clock in a multiplexing process or a phase difference between a multiplexed data signal and a demultiplexing reference clock in a demultiplexing process. The time-division data multiplexing system includes: a phase adjusting unit which adjusts a phase of each of a plurality of data signals having different phases from one another for enabling the data signals to be time-division multiplexed when a plurality of values of the data signals indicate a stable state; and a multiplexer time-division multiplexing the phase adjusted data signals according to a multiplexing reference clock.

Abstract: Provided is an apparatus and method for restoring clock signals by using a circulator in an optical transmission system. The apparatus includes a circulator, which allows one of N types of input data signals having different transmission speeds to circulate in a single direction, band pass filters, which extract N types of clock frequency components respectively corresponding to each transmission speed of the N types of input data signals, and clock amplifiers, which amplify each of the N types of clock frequency components.

Abstract: Provided are an integrated dielectric resonator filter and a clock extraction device using the integrated dielectric resonator filter. The integrated dielectric resonator filter includes: a microwave substrate; a disc type dielectric resonator installed on the microwave substrate and having predetermined diameter and height; an input and output transmission line installed on both sides of the disc type dielectric resonator to transmit input and output signals; and a metal cover enclosing the disc type dielectric resonator to form a predetermined volume, opened toward the input and output transmission line, and closed in an orthogonal direction to the input and output transmission line.

Abstract: Provided are an apparatus and method for generating an optical return-to-zero (RZ) signal using an electronic integrated circuit that generates an electric RZ signal. The apparatus for generating an optical RZ signal includes an electronic integrated circuit generating an electric return-to-zero (RZ) signal based on an input data signal and a clock signal, a driving amplifier amplifying the electric RZ signal, a light source outputting a carrier having a predetermined wavelength, and a modulator modulating the carrier according to the amplified RZ signal. The electronic integrated circuit can be constructed in a single electronic circuit chip, and thus the size of the optical transmission system can be reduced.

Abstract: Provided is a multi-mode open-loop type clock extraction apparatus. In the apparatus, a power divider block divides an input data signal into two data signals. A first band-pass filter block and a second band-pass filter block extract a first clock frequency component or a second clock frequency component contained in the data signal output from the power divider. A first amplifier block and a second amplifier block amplify the first clock frequency component and the second clock frequency component respectively. Accordingly, it is possible to extract the respective clock signals corresponding to N data rates from the N data signals with various data rates using a single clock extraction apparatus.

Abstract: Provided is a polarization division multiplexed optical transmission system including a transmitter and a receiver. The transmitter includes a first light source generating an optical signal having a linear polarization state; a second light source generating an optical signal having a horizontal polarization state; a first signal generator receiving a first data stream to modulate the optical signal output from the first light source using an M method; a second signal generator receiving a second data stream to modulate the optical signal output from the second light source using an N method; and a polarization beam combiner (PBC) multiplexing the optical signals that were modulated using the M and N methods while maintaining the linear and horizontal polarization states.

Abstract: An apparatus and a method for generating an optical carrier is disclosed. The apparatus includes: a light source generating a pump light; a SBS generator for stimulated Brillouin scattering the pump light to generate a stokes light from the light source; an attenuator for controlling an amplitude of the pump light from the light source to generate an amplitude controlled pump light; and a detector for heterodyne beating the stokes light and the amplitude controlled pump light to generate an optical carrier.

Abstract: A tunable high-order Bessel low pass filter which is applied to a multi-rate duobinary generation system of an optical communication system.

Abstract: An apparatus and a method for generating an optical carrier is disclosed. The apparatus includes: a light source generating a pump light; a SBS generator for stimulated Brillouin scattering the pump light to generate a stokes light from the light source; an attenuator for controlling an amplitude of the pump light from the light source to generate an amplitude controlled pump light; and a detector for heterodyne beating the stokes light and the amplitude controlled pump light to generate an optical carrier.

Abstract: Provided are an apparatus for optimizing bias voltage of an electro-optic modulator, a method therefor, and an optical transmission system using the method. The present research provides a bias voltage optimizing apparatus of an electro-optic modulator that can stabilize bias voltage supplied to the electro-optic modulator through automatic bias voltage initialization control by considering the point that the form of an optical output signal and the intensity of a clock component are changed according to the bias voltage of the electro-optic modulator, a method therefor and an optical transmission system using the method.