Electronics and Telecommunications Research Institute

Other

Korea Telecom

Je-Soo Ko

Sang-Soo Lee

Jae-Myoung Lee

Jong-Yoon Shin

Jaemyoung Lee

Wang-Yuhl Oh

Hyun-Jae Lee

Wan-Seok Seo

Yool Kwon

Sang-Kyu Lim

Hyunwoo Cho

Heuk Park

Seung-Il Myong

Ki-Ho Han

Jyung-Chan Lee

Wangjoo Lee

Jin-Soo Han

Wang-Joo Lee

Joon-Hak Bang

Kyung-Gyu Jeon

Dong-Yole Choi

Ji-Sung Jung

A clock extracting apparatus is provided. In the clock apparatus, two frequency components are made to have an equal magnitude by adjusting a temperature and current applied to an FP LD, and a clock signal is extracted by beating the two frequency components having the equal magnitude. The clock extracting apparatus includes: a circulator for changing a direction of an inputted optical signal; an adjuster for adjusting a characteristic and wavelength of a spectrum; and a clock extractor for selecting two frequency components having different magnitudes on the spectrum of the inputted optical signal, receiving an adjusted signals in which magnitudes of the two frequency components are made equal by the adjuster, making the two frequency components have an equal magnitude, and extracting a clock signal by beating the two frequency components having the equal magnitude.

Clock extracting apparatus

Provided are a frequency extracting apparatus and a signal extracting system employing the same. The signal extracting system can reduce the effect of an input signal pattern by extracting two frequency components and beating them to extract a desired clock signal, and improve a signal-to-noise ratio of an extracted clock signal. The frequency extracting apparatus includes: a circulator for changing an output direction of an input signal; a reflective filter for extracting a desired frequency component among frequency components of the input signal; a wavelength and amplitude controlling unit; and the frequency amplitude controller.

Frequency extracting apparatus and signal extracting system employing the same

The present invention relates to an apparatus and method for extracting an optical clock using filters and an amplifier. The object of the present invention is to provide an extraction of neighboring frequency components using wavelength fixed optical filters and an amplifier. In accordance with an aspect of the present invention, there is provided an apparatus for extracting an optical clock to extract a clock from the optical signal provided with plurality of peaks on a spectrum, including a first filter for extracting a central frequency component, a second filter for extracting a frequency component adjacent to the first frequency component, the amplifier for amplifying amplitude of the second frequency component until the amplitude of the second frequency component becomes the same as that of the first frequency component and the receiver for extracting a clock to do beating the first frequency component and the second frequency component.

Apparatus for extracting optical clock using filters and amplifier and method for the same

Provided is an apparatus for an optical clock extraction, which is capable of providing high optical amplification rate and more efficient noise cancellation by using a Fabry-Perot (FP) filter and an optical amplifier. In the apparatus, an optical circulator changes a direction of an inputted optical signal. The FP filter extracts different frequency components existing on a spectrum of the inputted optical signal and being spaced apart by a clock frequency, removes noise from a reflected and amplified optical signal, and transmits the resulting signal to the optical circulator. An optical amplifier performs a primary amplification to equalize two different frequency components outputted from the filter, and performs a secondary amplification on an optical signal reflected and fed back thereto. A reflector reflects the primarily-amplified optical signal to the optical amplifier.

Apparatus for optical clock extraction

Disclosed is a device and method for optical supervisory channel framing in an optical transport network system including at least one of an optical transmission section, an optical multiplex section, and an optical channel section. A maintenance signal is generated according to a first LOS (Loss OF Signal) signal generated from at least one of the optical transmission section, the optical multiplex section, and the optical channel section. The maintenance signal and a frame-related channel such as a message communication channel are multiplexed to generate an optical supervisory channel frame. The optical supervisory channel frame is output to another device including a repeater and a terminal system through a single supervisory channel.

Device and method for optical supervisory channel framing in optical transport network system

A switching apparatus for switching an optical channel overhead in an optical supervisory channel is disclosed. The switching apparatus can suppress a terminated optical channel defect occurred by a defect of upper layers of the optical channel or a defect of the optical channel transmitter and also can maintain the corresponding optical channel at the wavelength converted optical transport network system. Furthermore, an apparatus for forwarding an optical channel maintenance signal is disclosed too. The apparatus includes the switching apparatus and transmits only an add and drop optical channel maintenance signal information to the CPU and generate the LOS suppression signal with respect to the optical channel according to the occurrence of malfunction, thus directly transmitting the suppression signal to the corresponding optical channel unit.

Apparatus for switching optical channel overhead in optical supervisory channel of optical transport network system and apparatus for forwarding optical channel maintenance signal

An optical receiver in an optical communication system, and more particularly, to a method and an apparatus for optimizing a decision level of a signal output from an optical receiver to obtain a minimum bit error rate (BER) by measuring output characteristics of the optical receiver and adjusting a reference voltage of the optical receiver based on a measurement result. The provided method includes measuring the strength of an electric signal at a modulated frequency out of the frequency elements of the output electric signal in the optical receiver, generating a reference voltage based on the strength data of the electric signal, inputting the reference voltage to the optical receiver and re-measuring the strength of the electric signal output from the optical receiver to determine whether the strength of the signal is minimum, and maintaining the reference voltage when the strength of the signal is minimum and adjusting the reference voltage in other cases. Thus, the provided method optimizes the distribution of level one and level zero, i.e., a decision level, of the electric signal output from the optical receiver, so the efficiency and the performance of the transferred optical signal are maximized.

Method and apparatus for optimizing decision level of signal output from optical receiver

An apparatus for synchronizing a clock using a source synchronous clock is disclosed. The apparatus includes: channel receivers for receiving a source synchronous channel; divider for dividing the source synchronous clock to a low frequency clock; selectors for selecting one of the divided source synchronous clock and a system clock as a reference clock; detectors for generating a phase difference signal; phase difference signal selectors for selecting a phase difference signal from the detectors and a phase difference signal from an internal logic; and voltage oscillators for transmitting a clock synchronized to a source synchronous channel to the external optical transmission system by generating a predetermined synchronous frequency according to the selected phase difference signal.

Apparatus for synchronizing clock using source synchronous clock in optical transmission system

A method and apparatus for optical clock recovery using optical filters with fixed reflective wavelengths is provided. In the apparatus, a first filter receives an optical signal and extracts one out of two spectral lines corresponding to two side peaks that are second in magnitude to a peak and exist at both sides of a peak on the spectrum of the received optical signal. A second filter extracts a spectral line corresponding the largest peak on the spectrum of the received optical signal. An attenuator equalizes the power levels of the two spectral lines extracted by the first and second filters. A beating generation unit receives signals corresponding to the two equalized spectral lines and generates beating between the equalized spectral lines, thereby recovering a clock component.

Method and apparatus of clock recovery using optical filters

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.

Apparatus and method for generating optical carrier for microwave and millimeterwave photonics system

The present invention discloses an apparatus for suppressing stimulated Brillouin scattering and the method thereof that a threshold fiber input power is raised in order to prevent loss of an inputted light by stimulated Brillouin scattering being generated in a case that a signal having a strong intensity is inputted to the optical fiber and so a light signal having more strong intensity can be inputted to the optical fiber. The apparatus for suppressing the SBS includes a plurality of first transmission unit, each of which has a wavelength separation, for transmitting information signals through a signal channel; and a second transmission unit for generating and transmitting a supervisory signal of which a modulation frequency and an intensity generates a phase modulation to the plurality of information signals, through a supervisory channel. The modulation frequency and the intensity of the supervisory signal are modulated in phase to the information signals by a cross phase modulation effect, thereby broadening a line width of the information signal.

Apparatus and method for stimulated Brillouin scattering suppression using supervisory channel

An apparatus for compensating a polarization mode dispersion including a polarization adjusting means for adjusting polarization states of an optical beam having a differential group delay based on a polarization adjusting feedback control signal; a polarization beam splitting means for splitting principal states of polarization of the adjusted optical beam into a first polarization and a second polarization; a time delaying means for the first polarization based on a time delay feedback control signal; a polarization adjustment controlling means for controlling the polarization adjusting means based on a polarization adjusting feedback control signal; a time delay controlling means for controlling the time delaying means based on a time delay controlling feedback signal; and an electric combining means for combining a time-compensated first polarization and the second polarization transmitted through the optical tap.

Apparatus for compensating polarization mode dispersion

Disclosed is a Brillouin erbium-fiber laser system producing multiwavelengths with a dual spacing of 10 GHz and 20 GHz. The Brillouin erbium-fiber laser system includes: a Sagnac reflector generating even- and odd-order Strokes waves by launching input lights, a first unit forming a first resonator with the Sagnac reflector, wherein the first unit is coupled to a first directional coupler in the Sagnac reflector, a second unit forming a second resonator with the Sagnac reflector, wherein the second unit is coupled to the first directional coupler in the Sagnac reflector, and a third unit for inputting Brillouin pump light into one of first and the second units, whereby the optical fiber laser system outputs multiwavelengths with a dual spacing.

Growing community of inventors

Daejon, South Korea

Je-Soo Ko