Abstract: A tunable optical network unit (ONU) for a multi-wavelength passive optical network (MW PON) system and an operation method thereof are provided. The tunable ONU includes a cyclic tunable filter configured to have cyclic wavelength transmission properties that allow all wavelength channels of both a downstream signal and an upstream signal and to vary a wavelength to pass therethrough; a wavelength splitter configured to split an upstream signal wavelength band and a downstream signal wavelength band; a photodetector element configured to detect a downstream signal that is transmitted through the wavelength splitter, passing through the cyclic tunable filter which is aligned to a specific downstream signal wavelength channel; and a tunable transmitter configured to output to the wavelength transmitter an upstream signal of a wavelength channel that is determined based on an aligned downstream signal wavelength channel of the cyclic tunable filter.

Abstract: A wavelength-tunable optical transmission apparatus including an optical array unit comprising a plurality of light sources whose wavelengths are changed, an optical driving unit configured to receive an electrical signal transmitted from an external circuit, generate the current and input the generated current to the optical array unit, and a control unit configured to control the magnitude of current input to the optical array unit by controlling the optical driving unit.

Abstract: A transmitting and receiving apparatus using a wavelength-tunable filter according to an exemplary embodiment may include: a filter to generate a filtered optical-reception signal by passing only an allowed-to-be-passed wavelength by using Bragg grating filter; a wavelength setter to set the allowed-to-be-passed wavelength of the filter; and a photoelectric converter to perform photoelectric conversion on the filtered optical-reception signal into an electrical signal.

Abstract: Provided is an apparatus and a method for partial monitoring of an optical fiber, wherein the optical fiber monitoring apparatus includes a monitoring light transmitter to continuously output a monitoring light to the optical fiber based on a number of measuring time sections generated by dividing an optical fiber monitoring time section, a monitoring light receiver to receive a monitoring light fed back from the optical fiber, measure a monitoring light received based on different measuring time sections for each monitoring light, and store a result of the measuring in a storage medium, and an optical fiber monitor to monitor a status of the optical fiber based on the result of the measuring stored in the storage medium.

Abstract: A cost-effective optical coupling module for achieving an optical coupling by providing a predetermined space between an optical element and an optical waveguide without an additional lens is provided. The cost-effective optical coupling module includes an optical element configured to output or receive an optical signal, a substrate configured to allow the optical element to be fixed to an upper surface of one side thereof, an optical waveguide disposed above the optical element and coupled to the optical element, and spacers protruding at both sides of the substrate to maintain an interval between the optical waveguide and the optical element.

Abstract: There is provided an optical transceiver apparatus including an optical transmitter configured to transmit light of variable wavelength, an optical receiver configured to receive light generated from an opposite light source, and a controller configured to perform initialization to a wavelength corresponding to when an intensity of light received by the optical receiver is greater than or equal to a reference power, while varying the wavelength of light output by the optical transmitter.

Abstract: A board assembly for transmitting a high-speed signal and a method of manufacturing the same. The board assembly may include a submount board, a base board, and a contact member for a signal line. The submount board may include at least one first high-speed signal line formed on the surface thereof. The base board may include the submount board on one part of the upper surface thereof, and at least second high-speed signal line on the other part of the upper surface thereof, wherein the second high-speed signal lines corresponds to the first high-speed signal lines, respectively. The contact member for the signal line may be installed on the side of the submount board, and have an upper portion contacting the first high-speed signal line and a lower portion contacting the second high-speed signal line such that the first high-speed signal line contacts the second high-speed signal line.

Abstract: An interface for transmitting a high-speed signal and an optical module including the same. The interface may include a main substrate and a sub-substrate. The main substrate may have at least one high-speed signal line formed on the upper surface of the main substrate. The sub-substrate may have a first conductive line formed on the lower surface thereof so as to adjust high-speed signal transmission characteristics of the high-speed signal line, wherein the first conductive line may be coupled to the upper surface of the main substrate and partially overlap with the high-speed signal line.

Abstract: A multi-channel transmitter optical sub-assembly (TOSA) is provided. The multi-channel TOSA includes a stem including a sub-mount, a plurality of light sources mounted on the sub-mount, a common ground pad disposed at the sub-mount and connected to ground electrodes of the light sources in common, a common lead pin installed at the stem, and connected to the common ground pad, and a thermistor mounted on the sub-mount along with the light sources.

Abstract: An optical pulse output apparatus and method for controlling a width and an intensity of an optical pulse are provided. The optical pulse output apparatus may include a laser driver to control an optical pulse output by a laser, based on a plurality of channel signals, and a channel delay unit to delay at least one of the plurality of channel signals.

Abstract: An optical transceiver and an optical network system for performing a data communication and monitoring an optical link are disclosed. The optical transceiver may simultaneously perform the data communication and monitor the optical link, and a wavelength of an optical signal for the data communication and a wavelength of an optical signal for monitoring the optical link may be differently set.

Abstract: A control apparatus for controlling an optical receiver having delay paths comprises an optical variable attenuator configured to generate a variable signal and provide the variable signal to the optical receiver; a fine control voltage controller configured to generate a variable fine control voltage and input the variable fine control voltage to one path of the delay paths of the optical receiver; a photo-diode voltage monitor configured to detect a first voltage value and a second voltage value; a bit error rate (BER) checker configured to estimate a bit error rate (BER) according to a signal output from the optical receiver; and a controller configured to set a value of the variable signal and a value of the variable fine control voltage and to estimate the fine control voltage that makes the bit error rate a minimum according to the first voltage value and the second voltage value.

Abstract: A multi-channel transmitter optical sub-assembly (TOSA) is provided. The multi-channel TOSA includes a stem including a sub-mount, a plurality of light sources mounted on the sub-mount, a common ground pad disposed at the sub-mount and connected to ground electrodes of the light sources in common, a common lead pin installed at the stem, and connected to the common ground pad, and a thermistor mounted on the sub-mount along with the light sources.

Abstract: There is provided an optical transceiver apparatus including an optical transmitter configured to transmit light of variable wavelength, an optical receiver configured to receive light generated from an opposite light source, and a controller configured to perform initialization to a wavelength corresponding to when an intensity of light received by the optical receiver is greater than or equal to a reference power, while varying the wavelength of light output by the optical transmitter.

Abstract: A wavelength-tunable optical transmission apparatus including an optical array unit comprising a plurality of light sources whose wavelengths are changed, an optical driving unit configured to receive an electrical signal transmitted from an external circuit, generate the current and input the generated current to the optical array unit, and a control unit configured to control the magnitude of current input to the optical array unit by controlling the optical driving unit.

Abstract: A method of improving the performance of an optical time domain reflectometer (OTDR) is provided. The method according to an embodiment of the present invention can increase accuracy of a distance of the OTDR through an initial calibration method with respect to the refractive index of an optical fiber, and can accurately detect a fault position and accurately analyze a fault cause through a real-time calibration method with respect to the refractive index of the optical fiber when faults and performance degradation occur.

Abstract: An apparatus for receiving optical signals in DQPSK and method of controlling a phase offset in receiving optical signals for DQPSK is provided. An original optical signal modulated in DQPSK is received. The original optical signal is delayed by one bit to make a delay optical signal such that an interference on the original optical signal and the delay optical signal is performed. A control signal is generated by use of an interference result between the original optical signal and the delay optical signal. A phase offset for the interference between the original optical signal and the delay optical signal is controlled by use of the generated control signal. In receiving optical signals, the phase offset between the delay optical signal and the original optical signal is precisely controlled, thereby optimizing the transfer characteristics of an optical delay interferometer.

Abstract: An apparatus for receiving optical signals in DQPSK and method of controlling a phase offset in receiving optical signals for DQPSK is provided. An original optical signal modulated in DQPSK is received. The original optical signal is delayed by one bit to make a delay optical signal such that an interference on the original optical signal and the delay optical signal is performed. A control signal is generated by use of an interference result between the original optical signal and the delay optical signal. A phase offset for the interference between the original optical signal and the delay optical signal is controlled by use of the generated control signal. In receiving optical signals, the phase offset between the delay optical signal and the original optical signal is precisely controlled, thereby optimizing the transfer characteristics of an optical delay interferometer.

Abstract: An active alignment method for a multi-channel optical transmitter and receiver is disclosed. The active alignment method for a multi-channel optical transmitter includes actively aligning an optical signal generator with an optical multiplexer based on optical outputs of a plurality of wavelengths from the optical signal generator and an optical output of the optical multiplexer, and actively aligning the optical multiplexer with a fiber optic coupler based on an optical output of the optical multiplexer and an optical output of the fiber optic coupler.

Abstract: A control apparatus for controlling an optical receiver having delay paths comprises an optical variable attenuator configured to generate a variable signal and provide the variable signal to the optical receiver; a fine control voltage controller configured to generate a variable fine control voltage and input the variable fine control voltage to one path of the delay paths of the optical receiver; a photo-diode voltage monitor configured to detect a first voltage value and a second voltage value; a bit error rate (BER) checker configured to estimate a bit error rate (BER) according to a signal output from the optical receiver; and a controller configured to set a value of the variable signal and a value of the variable fine control voltage and to estimate the fine control voltage that makes the bit error rate a minimum according to the first voltage value and the second voltage value.